US20090071219A1

US20090071219A1 - Apparatus and method for forging premium coupling blanks

Info

Publication number: US20090071219A1
Application number: US11/855,551
Authority: US
Inventors: Jose McILROY
Original assignee: WESTERN CANADA MACHINING Inc
Current assignee: WESTERN CANADA MACHINING Inc
Priority date: 2007-09-14
Filing date: 2007-09-14
Publication date: 2009-03-19
Also published as: WO2009033267A1; AR067385A1

Abstract

A method and apparatus for forging a tubular forging stock to produce a forged product, preferably a premium coupling machining blank. The apparatus includes a holding die assembly defining a holding cavity for the forging stock and a press die apparatus including opposed first and second press dies movable within the holding cavity to forge the forging stock to produce the forged product. The holding die assembly may include opposed first and second holding dies defining respective portions of the holding cavity, wherein the holding dies are selectively relatively movable between a closed position for forging the forging stock and an open position for removal of the forged product. Alternately, the apparatus may include a knockout mechanism for dislodging the forged product from the holding cavity. Further, the apparatus may include a mechanism for controlling finning between the first and second press dies while the forged product is being produced.

Description

TECHNICAL FIELD

The present invention is directed at a forging apparatus and a forging method for producing a forged product from a forging stock. Preferably, the forging stock is a standard American Petroleum Institute (“API”) coupling blank and the forged product is a premium coupling machining blank.

BACKGROUND OF THE INVENTION

There is a growing demand in the oil and gas industry for Oil Country Tubular Goods (“OCTG”) premium couplings to couple adjacent casing or tubing joints or sections. A typical “premium coupling” includes a central pin seal and opposed threaded end portions. A compatible threaded pin end of the tubing or casing joint is threaded with or screwed into each respective threaded end portion of the premium coupling to abut against the central pin seal. The abutment of the pin end of each tubing or casing joint with the pin seal creates a relatively strong seal upon the application of a sufficient amount of torque.
The threaded connection of the adjacent casing or tubing joints by means of the premium coupling may be referred to as a “premium joint.” This premium joint tends to have improved sealing properties as compared with standard OCTG API tubing and casing joints. Further, the premium joint has been found to permit a relatively large degree of bending or twisting without causing any significant leaks or mechanical defects. For this reason, premium joints are relatively widely used in specialized drilling such as Steam Assisted Gravity Drainage (“SAGD”) in the oil sands, sour gas drilling, offshore drilling or directional drilling.
OCTG API “standard couplings” are typically made from steel or stainless steel pipe or tubular material referred to as standard API coupling stock. Standard API coupling stock comes in a variety of sizes and grades. Therefore, the standard API coupling stock is selected to provide a wall thickness just sufficient to permit the machining of the standard coupling therefrom. More particularly, a pipe or tubular material having a desired size and grade is selected and cut into a number of pieces or sections referred to as “cutoffs” or “blanks.” The blanks are then subjected to machining to produce the desired standard coupling. The machining process typically includes machining of the outer surface of the blank to provide a consistent outer shape or dimension. Further, the machining process includes “threading” of the inner surface of the blank to permit the threaded connections between the casing or tubing joints. It has been found that about 30% of the material comprising the standard coupling blank is typically removed from the inner surface during the machining process.
A similar process is applied for the production of premium couplings. However, standard API coupling stock and blanks do not provide a sufficient wall thickness to permit the machining of a premium coupling therefrom. Therefore, the premium coupling is typically made from a heavier or thicker walled “premium coupling stock.” Specifically, the premium coupling stock must have a greater wall thickness, as compared with standard coupling stock, which is sufficient to accommodate or permit the machining of the central pin seal of the premium coupling. In other words, the wall thickness of the premium coupling stock must be greater than or equal to the final maximum wall thickness of the premium coupling.
Thc need to utilize premium coupling stock increases the overall cost of production of the premium coupling. In addition, the varying wall thickness of the premium coupling along its length, particularly the requirement for the central pin seal, presents further challenges for manufacturing the premium coupling efficiently. In particular, the premium coupling stock, having the necessary wall thickness to accommodate the central pin seal, is first “rough bored” to provide a premium coupling blank. The inner surface of the premium coupling blank is then machined to provide the desired configuration of the inner surface of the premium coupling, including the threaded ends and pin seal.
As a result, this process for the production of premium couplings involves a large amount of machining, which increases the production costs and tends to result in a relatively large amount of wasted material. For example, it has been found that about 50% of the premium coupling stock material may be removed during the process of machining the premium coupling from the premium coupling stock. Further, the increased machining time tends to wear the tools faster, which increases the risk of machine down time and increases the tooling expense. As a result of all of the material inefficiencies, machining inefficiencies and inventory cost inefficiencies arising from the machining of premium couplings, such premium couplings tends to be relatively expensive. However, as indicated, the use of premium couplings is often required by the nature of the drilling or production operation.
In order to reduce some of the disadvantages associated with the machining of the premium coupling blank from premium coupling stock, it has been found that a premium coupling blank may be forged. Specifically, forging of the premium coupling blank may eliminate or reduce the need for “rough boring” of the premium coupling stock to produce the premium coupling blank, which may result in a relatively significant decrease in material losses.
For example, U.S. Pat. No. 5,363,545 issued Nov. 15, 1994 to Hirano et. al. is directed at a method for producing an OCTG coupling having a metal seal and a screw thread tapered toward its ends. The method includes cutting a plain pipe to a predetermined length and hot forging the pipe to deform the inside surface to achieve a predetermined thickened shape. After quenching and tempering the forged piece, the outside surface is machined into a final dimension. Further, the inside surface is also machined to a final predetermined shape and threaded to produce the coupling.
The forging process of Hirano et. al. is performed in a forging machine having a one piece outer die with an inside diameter slightly greater than the outside diameter of the desired coupling, and therefore, the outside diameter of the coupling stock to be inserted in the outer die. Further, the forging machine includes an inner die fixed to the inside surface of the outer die at a closed end of the outer die. Additionally, a punch is insertable within the outer die at the opposed open end of the outer die. The plain pipe is heated and inserted into the forging machine. Longitudinal compression is applied to the pipe by movement of the punch towards the fixed inner die within the outer die. The wall thickness of the plain pipe is about 50%-70% of the maximum wall thickness of the resulting coupling. The length of the plain pipe is about 110%-140% of the length of the resulting coupling.
Other forging apparatuses or machines are described in United States of America Publication No. US2004/0139781 A1 published Jul. 22, 2004 by Rozhdestvenskiv et. al., United States of America Publication No. US2006/0185417 A1 published Aug. 24, 2006 by Rozhdestvenskiy et. al. and United States of America Publication No. US2006/0225480 A1 published Oct. 12, 2006 by Ishida.
However, neither the forging process and machine of Hirano et. al., nor other known forging processes or apparatuses, have been found to be fully satisfactory.
Therefore, there remains a need in the industry for an improved forging apparatus and forging method for producing a forged product from a forging stock. More particularly, there is a need for an improved forging apparatus and an improved forging method for producing a premium coupling blank.

SUMMARY OF THE INVENTION

The present invention is directed at a forging apparatus and a forging method for producing a forged product. Further, the apparatus and the method are preferably directed at hot forging of the forging stock.
Further, the forged product is preferably a premium coupling machining blank, also referred to as a “premium coupling blank.” More particularly, the forged product is preferably an Oil Country Tubular Goods (“OCTG”) premium coupling blank, which is suitable for the subsequent production of an OCTG premium coupling therefrom, as described herein.
In order to provide a premium coupling blank having desired material specifications or characteristics, or having a desired API Grade, further processing of the forged product is typically required. For instance, the premium coupling blank preferably undergoes subsequent heat treating in order to achieve the desired or required material specifications of the premium coupling blank. By heat treating the forged premium coupling blank, the material properties of the premium coupling blank may be altered to provide a set of material properties which are suitable for later use as a premium coupling.
The forged product is produced or forged from a forging stock. The forging stock may be a length of any tubular pipe or tubular member comprised of a material suitable for, and compatible with, forging and subsequent heat treatment and capable of producing a premium coupling blank having the desired specifications or characteristics, such as a desired API Grade. Further, the forging stock is preferably comprised of steel, stainless steel or other suitable metal. Accordingly, the forging stock may be comprised of standard tubing, tubing blanks, casing or casing blanks. However, preferably, the forging stock is comprised of a length of standard API coupling stock or a standard API coupling blank or cut-off, comprised of steel or stainless steel pipe. In other words, standard coupling stock is preferably utilized, rather than premium coupling stock, in the production of the premium coupling blank.
Thus, preferably, the forging apparatus is configured to produce the premium coupling machining blank from a length of a tubular pipe as a forging stock, wherein the tubular pipe has a wall thickness, wherein the premium coupling machining blank has a maximum wall thickness, and wherein the wall thickness of the tubular pipe is less than the maximum wall thickness of the premium coupling machining blank.
In the preferred embodiment, the tubular pipe is comprised of a length of standard API coupling stock or a standard API coupling blank or cut-off. Standard API coupling stock typically has a substantially uniform wall thickness along the length thereof. Further, the maximum wall thickness of the premium coupling machining blank is preferably defined by a central pin seal portion, which subsequently provides the pin seal of the premium coupling.
In addition, the premium coupling machining blank has a minimum wall thickness and wherein the wall thickness of the tubular pipe is preferably greater than the minimum wall thickness of the premium coupling machining blank. However, in some embodiments, the wall thickness of the tubular pipe may be less than the minimum wall thickness of the premium coupling blank.
Further, the premium coupling machining blank has a length and wherein the length of the premium coupling machining blank is preferably greater than the length of the tubular pipe. Finally, the outer diameter or dimension of the tubular pipe is preferably about or substantially similar to the outer diameter or dimension of the premium coupling machining blank.
Thus, in the preferred embodiment, forging of the tubular pipe results in a shifting of an amount of the pipe material towards the centre of the premium coupling blank to produce a relatively thicker walled portion to accommodate the central pin seal portion of the premium coupling blank. Further, forging of the tubular pipe also preferably results in an extrusion of the pipe material towards the ends of the premium coupling blank to provide a longer premium coupling blank as compared with the tubular pipe.
As stated, in one aspect of the invention, the invention is directed at a forging apparatus. The forging apparatus is preferably comprised of a holding die assembly having a first end and a second end and defining a holding cavity extending between the first end and the second end. In addition, the forging apparatus is preferably comprised of a press die apparatus. The press die apparatus is comprised of a first press die and a second press die, which are preferably movable within the holding cavity to act upon the forging stock to produce the forged product.
The holding die assembly may be comprised of one or a plurality of pieces, sections or die components. However, the forging apparatus preferably permits the forged product to be removed from the forging apparatus in a relatively easy or efficient manner. Thus, in some embodiments, the forging apparatus is further comprised of a “knockout” mechanism for dislodging the forged product from the forging apparatus, and particularly from the holding die assembly, following the forging operation. In particular, a knockout mechanism is preferable where the holding die assembly is comprised of a single outer section or die component. In this instance, the knockout mechanism permits the dislodging of the forged product from the holding cavity following the forging operation.
In further embodiments of the forging apparatus, the holding die assembly is comprised of a “split” outer die. In other words, at least two outer sections or die components together comprise the holding die assembly, wherein the die components are relatively movable between a closed position for forging of the forged product and an open position to permit removal of the forged product therefrom.
In one such embodiment of the forging apparatus, the forging apparatus is comprised of:

- (a) a holding die assembly having a first end and a second end and defining a holding cavity extending between the first end and the second end, the holding die assembly comprising a first holding die defining a first portion of the holding cavity and further comprising a second holding die opposed to the first holding die and defining a second portion of the holding cavity, wherein the first holding die and the second holding die are selectively relatively movable toward each other to a closed position of the holding die assembly and away from each other to an open position of the holding die assembly, and wherein the first holding die, the second holding die and the holding cavity are configured so that a forged product produced by the forging apparatus may be removed from the holding cavity when the holding die assembly is in the open position; and
- (b) a press die apparatus comprising:
  - (i) a first press die which is selectively reciprocable in order to extend within and withdraw from the holding cavity from the first end of the holding die assembly; and
  - (ii) a second press die which is selectively reciprocable in order to extend within and withdraw from the holding cavity from the second end of the holding die assembly.

In still further embodiments of the forging apparatus, the forging apparatus may include a finning control mechanism for controlling finning between the first press die and the second press die while the forged product is being produced by the forging apparatus. In one such embodiment, the forging apparatus is comprised of:

- (a) a holding die assembly having a first end and a second end and defining a holding cavity extending between the first end and the second end;
- (b) a press die apparatus comprising a first press die and a second press die opposed to the first press die, wherein the first press die and the second press die are selectively relatively movable toward each other within the holding cavity to a closed position of the press die apparatus and away from each other to an open position of the press die apparatus;, and
- (c) a finning control mechanism for controlling finning between the first press die and the second press die while the forged product is being produced by the forging apparatus.

As indicated, in some embodiments, the holding die assembly is comprised of a first holding die and a second holding die opposed to the first holding die. In this instance, preferably, the first holding die defines a first portion of the holding cavity and the second holding die defines a second portion of the holding cavity. In addition, in such embodiments, the first holding die and the second holding die define a holding die interface plane. The holding die interface plane preferably extends between the first end and the second end of the holding die assembly.
The holding die assembly, including the first holding die and the second holding die, may be configured such that the holding die interface plane has any orientation compatible with and suitable for the operation of the forging apparatus. For instance, the holding die interface plane may be oriented substantially vertically or horizontally. Preferably, the first holding die and the second holding die are configured so that the holding die interface plane is substantially horizontal. In this instance, one of the first holding die and the second holding die is a bottom holding die, while the other of the first holding die and the second holding die is a top holding die.
Further, as indicated, in some embodiments, the first holding die and the second holding die are selectively relatively movable toward each other to a closed position of the holding die assembly and away from each other to an open position of the holding die assembly. Preferably, one of the first holding die and the second holding die is in a fixed position and the other of the first holding die and the second holding die is movable. Preferably, where the holding die interface is substantially horizontal, the first holding die is a bottom holding die and the second holding die is a top holding die, wherein the bottom holding die is fixed and wherein the top holding die is movable. Alternately, the top holding die may be fixed, while the bottom holding die is movable. Further, the first holding die, the second holding die and the holding cavity are configured so that the forged product produced by the forging apparatus may be removed from the holding cavity, preferably readily or relatively easily or efficiently, when the holding die assembly is in the open position.
As well, in some of the embodiments of the forging apparatus comprising a first holding die and a second holding die, the holding die assembly may be further comprised of a first end retainer which projects into the holding cavity adjacent to the first end of the holding die assembly and wherein the holding die assembly is further comprised of a second end retainer which projects into the holding cavity adjacent to the second end of the holding die assembly.
The first end retainer and the second end retainer act to retain the forged product in the holding cavity during the release of the press die apparatus, particularly during the withdrawal of one or both of the first press die and the second press die from the holding cavity. In other words, the first and second end retainers prevent or inhibit the forged product from being pulled along by the first and second press dies respectively during the withdrawal thereof, thus facilitating the subsequent removal of the forged product from the forging apparatus.
Preferably, each of the first end retainer and the second end retainer is comprised of one or more retainer members. Further, each of the first end retainer and the second end retainer is preferably associated with one or both of the first holding die and the second holding die.
In some embodiments, the first holding die may be comprised of a retainer member adjacent to the first end of the holding die assembly and wherein the first end retainer is comprised of the retainer member. Further, the second holding die may be comprised of a retainer member adjacent to the first end of the holding die assembly and wherein the first end retainer is comprised of the retainer member. However, preferably, the first holding die is comprised of a retainer member adjacent to the first end of the holding die assembly, the second holding die is comprised of a retainer member adjacent to the first end of the holding die assembly and wherein the first end retainer is comprised of the retainer members.
In other embodiments, the first holding die may be comprised of a retainer member adjacent to the second end of the holding die assembly and wherein the second end retainer is comprised of the retainer member. Further, the second holding die may be comprised of a retainer member adjacent to the second end of the holding die assembly and wherein the second end retainer is comprised of the retainer member. However, preferably, the first holding die is comprised of a retainer member adjacent to the second end of the holding die assembly, the second holding die is comprised of a retainer member adjacent to the second end of the holding die assembly and wherein the second end retainer is comprised of the retainer members.
In the preferred embodiment, the first holding die is comprised of a retainer member adjacent to each of the first end and the second end of the holding die assembly, wherein the second holding die is comprised of a retainer member adjacent to each of the first end and the second end of the holding die assembly, and wherein the first end retainer and the second end retainer are comprised of the retainer members.
However, in some embodiments, one or both of the first and second holding dies may lack the retainer member adjacent one or both of the first and second ends of the holding die assembly, particularly in instances where the presence of the retainer member may impede or interfere with the removal of the forged product.
Further, as indicated, the forging apparatus is comprised of a press die apparatus for forging the forging stock held within the holding die assembly to produce the forged product. The press die apparatus is preferably adapted to be movable within the holding cavity of the holding die assembly and is configured to provide the forged product having a desired shape and configuration.
The press die apparatus is comprised of a first press die and a second press die. Preferably, the first press die and the second press die are opposed. Further, the first press die and the second press die are preferably selectively relatively movable toward each other within the holding cavity to a closed position of the press die apparatus and away from each other to an open position of the press die apparatus. Either or both of the first and second press dies may be movable relative to the other. Preferably, both the first and second press dies are selectively reciprocable. More preferably, the first press die is selectively reciprocable in order to extend within and withdraw from the holding cavity from the first end of the holding die assembly and the second press die is selectively reciprocable in order to extend within and withdraw from the holding cavity from the second end of the holding die assembly.
Thus, the first press die and the second press die define a variable press die gap between them as they relatively move toward and away from each other, or as they extend within and withdraw from the holding cavity. As indicated, the forging apparatus may be further comprised of the finning control mechanism for controlling finning between the first press die and the second press die. The finning control mechanism is preferably comprised of a variable spanning device for spanning the press die gap throughout a range of the press die gap.
The variable spanning device may be comprised of any structure or mechanism capable of spanning, or in other words extending across, the variable press die gap between the first and second press dies. For instance, one or both of the first press die and the second press die may include an inner member or inner die telescopically received within the respective press die such that the inner die is capable of relative reciprocable movement in order to extend or retract therefrom.
Specifically, in some embodiments, the spanning device is comprised of an inner die telescopically received within a one of the first press die and the second press die such that the inner die is capable of reciprocable movement, relative to the one of the first press die and the second press die, between an extended position and a retracted position in order to span the press die gap throughout the range of the press die gap.
However, preferably, the spanning device is comprised of a first inner die telescopically received within the first press die, wherein the first inner die is capable of reciprocable movement relative to the first press die between an extended position and a retracted position, and the spanning device is further comprised of a second inner die telescopically received within the second press die, wherein the second inner die is capable of reciprocable movement relative to the second press die between an extended position and a retracted position.
In addition, the first inner die and the second inner die are adapted to engage each other, preferably within the range of the press die gap, so that finning between the first press die and the second press die is controlled. Thus, the first inner die and the second inner die are adapted to engage each other as at least one, and preferably both, of the first press die and the second press die are extended within the holding cavity in order to span the press die gap throughout the range of the press die gap.
In one embodiment of the finning control mechanism, the inner die is preferably biased toward the extended position and movable toward the retracted position by overcoming the bias. Thus, in some embodiments, at least one of the first inner die and the second inner die is biased toward the extended position and movable toward the retracted position by overcoming the bias. Preferably, the first inner die and the second inner die are each biased toward the extended position and movable toward the retracted position by overcoming the bias.
One or both of the first and second inner dies may be biased by any mechanism, structure or orientation capable of providing a biasing force sufficient to urge the respective inner die toward the extended position, while permitting movement toward the retracted position upon overcoming the biasing force. For instance, the forging apparatus, and preferably the finning control mechanism, may be comprised of a first biasing mechanism, such as a spring, for biasing the first inner die toward the extended position and may further be comprised of a second biasing mechanism, such as a spring, for biasing the second inner die toward the extended position. In this instance, the spring may also absorb some impact shock during the forging operation.
In a more preferred embodiment of the finning control mechanism, the inner die is actuatable toward the extended position. Thus, preferably, at least one of the first inner die and the second inner die is actuatable toward the extended position. More preferably, the first inner die and the second inner die are each actuatable toward the extended position.
One or both of the first inner die and the second inner die may be actuated to the extended position by any mechanical, hydraulic or electrical mechanism, device or structure capable of causing the inner die to extend or reciprocate outwardly relative to the press die. In one embodiment, the first inner die and the second inner die are each hydraulically actuatable toward the extended position. Similarly, the inner die, such as one or both of the first inner die and the second inner die, may be actuated to the retracted position by any mechanical, hydraulic or electrical mechanism, device or structure capable of causing the inner die to retract, withdraw or reciprocate inwardly relative to the press die.
In a further aspect of the invention, the invention is directed at a forging method for forging the forging stock into the forged product, as described above. The forging method may be performed utilizing any forging apparatus capable of carrying out the method and each of the steps thereof. However, preferably, the forging method is performed utilizing the forging apparatus of the within invention, as described herein.
In addition, the forging method is preferably utilized for hot forging the forging stock. Thus, prior to commencement of the forging method as described herein, the forging stock may be heated to a temperature suitable for, and compatible with, the subsequent forging of the forging stock to produce a forged product of a desirable quality.
In one embodiment of the forging method for forging the forging stock into the forged product, the forging method comprises:

- (a) providing a holding die assembly having a first end and a second end and defining a holding cavity extending between the first end and the second end, the holding die assembly comprising a first holding die defining a first portion of the holding cavity and further comprising a second holding die opposed to the first holding die and defining a second portion of the holding cavity, wherein the first holding die and the second holding die are selectively relatively movable toward each other to a closed position of the holding die assembly and away from each other to an open position of the holding die assembly;
- (b) positioning the forging stock between the first holding die and the second holding die when the holding die assembly is in the open position;
- (c) relatively moving the first holding die and the second holding die toward each other to the closed position of the holding die assembly so that the forging stock is positioned in the holding cavity between the first holding die and the second holding die;
- (d) providing a first press die which is selectively reciprocable in order to extend within and withdraw from the holding cavity from the first end of the holding die assembly, and providing a second press die which is selectively reciprocable in order to extend within and withdraw from the second end of the holding die assembly;
- (e) extending the first press die within the holding cavity from the first end of the holding die assembly and extending the second press die within the holding cavity from the second end of the holding die assembly in order to forge the forging stock, thereby producing the forged product;
- (f) withdrawing the first press die from the holding cavity from the first end of the holding die assembly and withdrawing the second press die from the holding cavity from the second end of the holding die assembly while maintaining the holding die assembly in the closed position;
- (g) relatively moving the first holding die and the second holding die away from each other to the open position of the holding die assembly; and
- (h) removing the forged product from the holding cavity while the holding die assembly is in the open position.

As well, the forging method may further comprise controlling finning between the first press die and the second press die while producing the forged product. In one such embodiment, the forging method for forging the forging stock into the forged product comprises:

- (a) providing a holding die assembly having a first end and a second end and defining a holding cavity extending between the first end and the second end;
- (b) positioning the forging stock in the holding cavity;
- (c) providing a press die apparatus comprising a first press die and a second press die opposed to the first press die, wherein the first press die and the second press die are selectively relatively movable toward each other within the holding cavity to a closed position of the press die apparatus and away from each other to an open position of the press die apparatus;
- (d) relatively moving the first press die and the second press die to the closed position of the press die apparatus in order to forge the forging stock, thereby producing the forged product;
- (e) controlling finning between the first press die and the second press die while producing the forged product;
- (f) relatively moving the first press die and the second press die to the open position of the press die apparatus; and
- (g) removing the forged product from the holding cavity.

Thus, the holding die assembly, as described, is provided and the forging stock is positioned in the holding cavity. As indicated, if necessary, the forging stock is preferably heated to a desirable hot forging temperature prior to positioning the forging stock in the holding cavity. Positioning of the forging stock may accomplished by any method or in any manner. For instance, where the holding die assembly is comprised of a single or unitary piece or component, the forging stock may simply be inserted through the first or second end into the holding cavity.
However, where the holding die assembly is comprised of the first holding die and the second holding die, movable between the open position and the closed position, the positioning of the forging stock in the holding cavity is preferably comprised of positioning the forging stock between the first holding die and the second holding die when the holding die assembly is in the open position.
In addition, in such embodiments, the method preferably includes relatively moving the first holding die and the second holding die toward each other to the closed position of the holding die assembly so that the forging stock is positioned in the holding cavity between the first holding die and the second holding die, in order to permit the production of the forged product. Further, the method preferably includes relatively moving the first holding die and the second holding die away from each other to the open position of the holding die assembly, in order to permit removal of the forged product.
The relative moving steps may be comprised of moving one or both of the first holding die and the second holding die relative to the other between the open and closed positions of the holding die assembly. Preferably, relatively moving the first holding die and the second holding die is comprised of maintaining one of the first holding die and the second holding die in a fixed position while moving the other of the first holding die and the second holding die. For instance, the relative moving step may be comprised of maintaining the first holding die in a fixed position while moving the second holding die.
Further, once the forging stock is positioned in the holding cavity, the method comprises providing a press die apparatus or providing a first press die and a second press die, as described herein with respect to the apparatus.
In some embodiments, the method comprises relatively moving the first press die and the second press die to the closed position of the press die apparatus in order to forge the forging stock, thereby producing the forged product. The method also comprises relatively moving the first press die and the second press die to the open position of the press die apparatus. Preferably, relatively moving the first press die and the second press die to either the open position or the closed position includes concurrently or simultaneously moving both the first press die and the second press die relative to the other.
In further embodiments, the method comprises extending the first press die within the holding cavity from the first end of the holding die assembly and extending the second press die within the holding cavity from the second end of the holding die assembly in order to forge the forging stock, thereby producing the forged product. Preferably, extending the first press die and extending the second press die are conducted or performed concurrently or simultaneously. The method also comprises withdrawing the first press die from the holding cavity from the first end of the holding die assembly and withdrawing the second press die from the holding cavity from the second end of the holding die assembly, preferably while maintaining the holding die assembly in the closed position. Preferably, withdrawing the first press die and withdrawing the second press die are also conducted or performed concurrently or simultaneously.
As well, the method may further comprise retaining the forged product in the holding cavity while withdrawing the first press die from the holding cavity and withdrawing the second press die from the holding cavity. The forged product may be retained in the holding cavity in any manner and by any mechanism or structure capable of inhibiting the movement of the forged product during the withdrawal of the first and second press dies. However, where the holding die assembly is comprised of the first holding die and the second holding die, as described previously, retaining the forged product in the holding cavity may be comprised of gripping the forged product between the first holding die and the second holding die. In this instance, the forged product may be gripped in any manner capable of holding and inhibiting the movement of the forged product relative to the first and second holding dies.
In addition, in other embodiments, retaining the forged product in the holding cavity may be comprised of engaging the forged product with a first end retainer associated with the first end of the holding die assembly. Retaining the forged product in the holding cavity may alternately be comprised of engaging the forged product with a second end retainer associated with the second end of the holding die assembly. However, retaining the forged product in the holding cavity is preferably comprised of both engaging the forged product with a first end retainer associated with the first end of the holding die assembly and engaging the forged product with a second end retainer associated with the second end of the holding die assembly. Where at least one retainer projects into the holding cavity, the holding die assembly is comprised of the first holding die and the second holding die in order to permit the movement of the holding die assembly to the open position for removal of the forged product.
As well, as indicated, the method may further comprise controlling finning between the first press die and the second press die while producing the forged product. Finning of the material of the forging stock tends to occur during forging as the first press die and the second press die are moved together or into engagement with each other to produce the forged product. Thus, in some embodiments, finning is preferably controlled while relatively moving the first press die and the second press die to the closed position of the press die apparatus in order to forge the forging stock. In other embodiments, finning is controlled while extending the first press die within the holding cavity from the first end of the holding die assembly and extending the second press die within the holding cavity from the second end of the holding die assembly in order to forge the forging stock.
In such embodiments, controlling finning is preferably comprised of spanning the variable press die gap throughout a range of the press die gap. Spanning the press die gap may be comprised of providing the variable spanning device, as described previously, for spanning the press die gap throughout a range of the press die gap. Thus, spanning the press die gap may be further comprised of engaging the first inner die and the second inner die with each other in order to span the press die gap throughout the range of the press die gap.
In one embodiment, spanning the press die gap is further comprised of biasing the inner die toward the extended position and moving the inner die toward the retracted position by overcoming the bias. Preferably, spanning the press die gap is further comprised of biasing at least one of the first and second inner dies, and more preferably each of the first inner die and the second inner die, toward the extended position and wherein spanning the pres die gap is further comprised of moving at least one of the first and second inner dies, and more preferably each of the first inner die and the second inner die, toward the retracted position by overcoming the bias.
In a more preferred embodiment, spanning the press die gap is further comprised of actuating the inner die toward the extended position. Thus, preferably, at least one of the first inner die and the second inner die is actuated toward the extended position. More preferably, spanning the press die gap is further comprised of actuating each of the first inner die and the second inner die toward the extended position. More particularly, spanning the press die gap is preferably further comprised of hydraulically actuating each of the first inner die and the second inner die toward the extended position. Similarly, the method may include actuating the inner die, such as one or both of the first inner die and the second inner die, toward the retracted position, and preferably hydraulically actuating both the first and second inner dies. Whether being actuated to the extended or retracted position, the inner die may be actuated in any manner, such as mechanically, hydraulically or electrically. However, preferably, the inner die is actuated hydraulically.
The method also includes removing the forged product from the holding cavity. Preferably the forged product is removed from the holding cavity in a relatively easy or efficient manner.
In some embodiments, such as where the holding die assembly is comprised of a single outer section or die component, removing the forged product may include dislodging the forged product from the holding cavity. In this instance, dislodging the forged product is preferably performed using the knockout mechanism discussed above.
In other embodiments, such as where the holding die assembly is comprised of a first holding die and a second holding die, the holding die is preferably moved to the open position to permit the removal of the forged product. In other words, the method includes removing the forged product from the holding cavity while the holding die assembly is in the open position.
The forged product may then be subjected to further treating in order to achieve desired or required material specifications of the forged product. For instance, where the forged product is a premium coupling blank, heat treating may be required to achieve the desired or required material specifications or desired API Grade of the premium coupling blank. For instance, the necessary material specifications may be determined, at least in part, by the need to machine the premium coupling blank to produce the premium coupling, such as an OCTG premium coupling, and by the need to provide an OCTG premium coupling suitable for its intended use. In other words, by beat treating the forged premium coupling blank, the material properties of the premium coupling blank may be altered to provide a set of material properties which are suitable for premium coupling use.
Heat treating of the forged product may include any suitable heat treating technique or combination of techniques suitable for use in heat treating metal components, particularly steel or stainless steel. In some embodiments, the heat treating of the forged product is preferably comprised of quenching and tempering, normalizing or annealing.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a premium coupling;

FIG. 2 is a cross-sectional view of a forged product, particularly a premium coupling blank, produced by the forging apparatus and forging method of the invention;

FIG. 3 is a schematic side view of a forging apparatus of the invention for production of the premium coupling blank shown in FIG. 2, the forging apparatus including a holding die assembly and a press die apparatus;

FIG. 4 is a detailed view of the holding die assembly and the press die assembly of the forging apparatus shown in FIG. 3;

FIG. 5 is a detailed view of an alternate holding die assembly for use in the forging apparatus shown in FIG. 3;

FIG. 6 is a schematic side view of an alternate forging apparatus of the invention including a holding die assembly, a press die apparatus and a knockout mechanism;

FIGS. 7 a-7 b are cross-sectional views of examples of potential finning of a forging stock in the press die apparatus;

FIGS. 8 a-8 c are a side view of the holding die assembly and an alternate press die apparatus of the forging apparatus of FIG. 3, wherein the press die apparatus includes a finning control mechanism and wherein FIGS. 8 a, 8 b and 8 c show the operation of the finning control mechanism in sequence;

FIG. 9 is a detailed side view of a portion of the finning control mechanism shown in FIG. 8;

FIG. 10 is a detailed side view of a portion of an alternate finning control mechanism; and

FIG. 11 is a schematic diagram of a process for heat treating a forged product produced by the forging method and forging apparatus of the invention.

DETAILED DESCRIPTION

The present invention is for use in the production of a forged product (20). Preferably, the forged product (20) is a premium coupling blank as shown in FIG. 2. More preferably, the premium coupling blank (20) is an OCTG premium coupling blank suitable for the subsequent production of a premium coupling (22) therefrom, particularly an OCTG premium coupling, of the type shown in FIG. 1.
Referring to FIG. 2, the premium coupling blank (20) is comprised of a wall (24) defining a bore (26) extending therethrough between a first end (28) and a second end (30) of the premium coupling blank (20). A length (32) of the premium coupling blank (20) is defined between the first end (28) and the second end (30). As well, the premium coupling blank (20) defines a wall thickness between an outer surface (34) of the wall (24) and the bore (26). The wall thickness of the premium coupling blank (20) varies through its length (32), as shown in FIG. 2, to provide a minimum wall thickness (36) of the premium coupling blank (20) and a maximum wall thickness (38) of the premium coupling blank (20). The maximum wall thickness (38) is preferably substantially centrally located between the first and second ends (28, 30) in order to provide a central pin seal portion (40) of the premium coupling blank (20).
The premium coupling blank (20) of FIG. 2 is provided to permit the production of the premium coupling (22) therefrom. In particular, following the forging of the premium coupling blank (20) and any subsequent heat treating, as discussed further below, the bore (26) of the premium coupling blank (20) is preferably machined such that the central pin seal portion (40) provides a pin seal (41), which may also be referred to as torque shoulder or metal seal, of the premium coupling (22). Further, the premium coupling blank (20) is threaded adjacent the first and second ends (28, 30) to provide opposed threaded end portions (42) of the premium coupling (22).
Heat treating of the premium coupling blank (20) prior to the subsequent machining and threading is preferably performed in order to achieve the desired or required material specifications and API Grade such that the required premium coupling (22) may be produced. Specifically, heat treating alters the material properties of the premium coupling blank (20) to provide a set of material properties suitable for use as the intended premium coupling (22).
The premium coupling blank (20), being the forged product, is forged from a forging stock comprised of a length of a tubular pipe (44). The forging stock or tubular pipe (44) is preferably comprised of steel or stainless steel suitable for, and compatible with, forging and subsequent heat treating in order to produce the premium coupling blank (20) therefrom having desired specifications or characteristics. In the preferred embodiment, the tubular pipe (44) is comprised of standard API coupling stock or a standard API coupling blank or cut-off. Alternately, the tubular pipe (44) may be comprised of a length of standard tubing or a tubing blank.
As shown in FIG. 8 a, the tubular pipe (44) has a first end (46) and an opposed second end (48) and defines a bore (50) extending therethrough. Further, the tubular pipe (44) has a length (52) defined between the first and second ends (46, 48) and has a wall thickness (54). The wall thickness (54) is preferably substantially uniform along the length (52) of the tubular pipe (44), although some minor variation in wall thickness is permissible. For instance, where the tubular pipe (44) is comprised of a standard API coupling blank or cut-off, the outer dimension of the pipe may be inconsistent, due to being “out-of-round” or having rough edges from saw cuts. In circumstances in which the wall thickness (54) of the tubular pipe (44) varies, the wall thickness (54) is defined by the thickest portion or the maximum cross-sectional dimension through the length (52) of the tubular pipe (44).
The wall thickness (54) of the tubular pipe (44) is preferably less than the maximum wall thickness (38) of the premium coupling blank (20). Further, the wall thickness (54) of the tubular pipe (44) is preferably greater than the minimum wall thickness (36) of the premium coupling blank. (20). However, in some instances, such as where the tubular pipe (44) is comprised of a length of standard tubing or a tubing blank, the wall thickness (54) of the tubular pipe (44) may be less than the minimum wall thickness (36) of the premium coupling blank. (20).
Finally, the length (32) of the premium coupling blank (20) is preferably greater than the length (52) of the tubular pipe (44). In this regard, the length (52) of the tubular pipe (44) is selected, in combination with the wall thickness (54), such that the tubular pipe (44) provides sufficient material for formation or production of the desired configuration of the premium coupling blank (20), including the central pin seal portion (40).
Accordingly, in a preferred embodiment, the forging of the tubular pipe (44) causes a shifting in the material of the tubular pipe (44). First, an amount of the material is shifted centrally to define the maximum wall thickness (38) of the premium coupling blank (20), having a dimension sufficient to accommodate the central pin seal portion (40). Second, an amount of the material is preferably extruded or shifted towards the ends (28, 30) of the premium coupling blank (20) to provide the desired length (32) of the premium coupling blank (20) and to define the minimum wall thickness (36) of the premium coupling blank (20). Thus, the forging preferably causes both a localized increase and a localized decrease in the wall thickness of the resulting premium coupling blank (20) as compared with the tubular pipe (44).
Referring to FIGS. 3-4, a forging apparatus (56) is provided. In the preferred embodiment, the forging apparatus (56) is utilized to produce the forged product, being the premium coupling blank (20), from the forging stock, being the tubular pipe (44). The forging apparatus (56) is comprised of a holding die assembly (58) and a press die apparatus (60).
The holding die assembly (58) has a first end (62), a second end (64) and a holding cavity (66) defined between the first and second ends (62, 64). The holding cavity (66) is provided for holding or gripping the tubular pipe (44) during the forging operation and to maintain or provide an outer dimension of the premium coupling blank (20). The holding cavity (66) is configured so that the forged premium coupling blank (20) may be readily removed from the holding cavity (66) following the forging operation. Further, the press die apparatus (60) is comprised of a first press die (68) and a second press die (70), which are movable relative to each other within the holding cavity (66) in order to act upon the tubular pipe (44) to produce the premium coupling blank (20).
In a preferred embodiment, the holding die assembly (58) is comprised of greater than one component or outer die section in order to permit the holding die assembly (58) to be “split” or moved to an open position to more readily remove the premium coupling blank (20) forged therein. As shown in FIGS. 3 and 4, the holding die assembly (58) is preferably comprised of a first holding die (72) and an opposed second holding die (74). The first and second holding dies (72, 74) are movable between a closed position for forging of the premium coupling blank (20) and an open position to permit removal of the premium coupling blank (20). More particularly, each of the first and second holding dies (72, 74) defines a part or portion of the complete or entire holding cavity (66). Thus, the first holding die (72) defines a first portion (76) of the holding cavity (66) and the second holding die (74) defines a second portion (78) of the holding cavity (66). The first and second holding dies (72, 74), including the holding cavity (66), are configured so that the premium coupling blank (20) may be readily removed when the holding die assembly (58) is in the open position.
Further, if desired or required, the holding die assembly (58) may be comprised of one or more guide pins (not shown). The guide pins are pins that are provided to hold or guide the components or outer die sections of the holding die assembly (58), or to facilitate or maintain the positioning of the first and second holding dies (72, 74) relative to each other, during the forging operation.
The “split” nature of the holding die assembly (58) also permits the holding die assembly (58) to be sized and configured to produce a premium coupling blank (20) of a desired outer dimension or diameter in order to minimize any subsequent necessary machining of the outer surface (34) of the forged premium coupling blank (20) to produce the premium coupling (22). Further, the holding cavity (66) is preferably sized and configured such that the outer dimension or diameter of the tubular pipe (44) is substantially similar or identical to the outer dimension or diameter of the forged premium coupling blank (20). Accordingly, a tubular pipe (44) is selected having an outer dimension or diameter which matches or is substantially similar to the desired outer dimension or diameter of the required premium coupling (22). As a result, any necessary machining of the forged premium coupling blank (20) is reduced or minimized.
Where the holding die assembly (58) is not “split”, but is comprised of a single component or integral holding die, the internal diameter of the holding cavity (66) must be selected to accommodate a wide variety of potential shapes of the tubular pipe (44), such as where the tubular pipe (44) is “out-of-round” or has rough edges. As a result, the outer dimension or diameter of the resulting forged premium coupling blank (20) may be too large, requiring an amount of machining to provide the desired outer dimension or diameter of the premium coupling (22). Use of a split holding die assembly (58) permits the holding cavity (66) to be sized to produce a premium coupling blank (20) having an outer dimension or diameter more closely matching the desired outer dimension or diameter of the premium coupling (22), while still accommodating a relatively wide variety of potential shapes of the tubular pipe (44).
Further, the first and second holding dies (72, 74) define a holding die interface plane (80) therebetween which extends between the first and second ends (62, 64) of the holding die assembly (58). The holding die interface plane (80) may be oriented in any direction compatible with the configuration and operation of the forging apparatus (56). For example, as shown in FIG. 6, the holding die interface plane (80) may be oriented substantially vertically.
However, preferably, as shown in FIG. 3, the holding die interface plane (80) is oriented substantially horizontally. Thus, the first and second holding dies (72, 74) are configured so that the holding die interface plane (80) is substantially horizontal. Accordingly, as shown in FIG. 3, the first holding die (72) provides a bottom or lower holding die while the second holding die (74) provides a top or upper holding die, wherein the holding dies (72, 74) are selectively movable toward each other to the closed position of the holding die assembly (58) and away from each other to the open position of the holding die assembly (58).
The first or bottom holding die (72) is preferably fixed or held in a fixed position by the forging apparatus (56). The second or top holding die (74) is movable or adapted to be moved by the forging apparatus (56). The second holding die (74) may be moved by any suitable mechanism or device capable of mechanically, electrically or hydraulically actuating the second holding die (74) to move between the open and closed positions and capable of applying the necessary force or pressure through the second holding die (74), or capable of having the first and second holding dies (72, 74) locked or held in the closed position, to permit the forging of the tubular pipe (44) within the holding cavity (66). Preferably, the second holding die (74) is hydraulically actuated between the open and closed positions. Thus, the forging apparatus (56) is preferably comprised of a hydraulic press (82) operatively connected or associated with the second holding die (74). As shown in FIG. 3, the hydraulic press (82) preferably moves the second holding die (74) vertically towards and away from the first holding die (72).
Referring further to FIG. 3, the press die apparatus (60) is comprised of the first press die (68) and the second press die (70), which are selectively movable relative to each other. For instance, as shown in FIG. 6, one of the first press die (68) and the second press die (70) may be fixed within the holding cavity (66), while the other is movable within the holding cavity (66) in order to act upon the tubular pipe (44) therein.
However, as shown in FIGS. 3 and 4, preferably both of the first and second press dies (68, 70) are movable. The first and second press dies (68, 70) are movable or extendable toward each other within the holding cavity (66) to a closed position and are moveable or retractable away from each other to an open position. Specifically, the first press die (68) is selectively reciprocable in order to extend within and withdraw from the holding cavity (66) from the first end (62) of the holding die assembly (58). The second press die (70) is selectively reciprocable in order to extend within and withdraw from the holding cavity (66) from the second end (64) of the holding die assembly (58).
The first and second press dies (68, 70) are oriented to be compatible with the orientation of the holding die assembly (58), and particularly the holding die interface plane (80), such that the first and second press dies (68, 70) may access the holding cavity (66). For example, as shown in FIG. 6, where the holding die interface plane (80) is oriented substantially vertically, the first and second press dies (68, 70) arc oriented to move or reciprocate along a substantially vertical plane or direction.
However, as shown in FIGS. 3 and 4, where the holding die interface plane (80) is oriented substantially horizontally, the first and second press dies (68, 70) are oriented to move or reciprocate along a substantially horizontal plane or direction. Each of the first and second press dies (68, 70) may be moved by any suitable mechanism or device capable of mechanically, electrically or hydraulically actuating the first or second press die (68, 70) respectively to reciprocate between the open and closed positions of the press die apparatus (60) and capable of applying the necessary force or pressure through the press die apparatus (60) to permit the forging of the tubular pipe (44) within the holding cavity (66).
Preferably, each of the first and second press dies (68, 70) is hydraulically actuated between the open and closed positions. Thus, the forging apparatus (56) is preferably comprised of a hydraulic press (84) operatively connected or associated with each of the first and second press dies (68, 70). For instance, as shown in FIGS. 8 and 9, the first and second press dies (68, 70) may be bolted or otherwise fastened to the respective hydraulic press (84). As shown in FIG. 3, a pair of hydraulic presses (84) preferably move the first and second press dies (68, 70) horizontally towards and away from each other to extend within and withdraw from the holding cavity (66) respectively. As the first and second press dies (68, 70) are extended within the holding cavity (66), the tubular pipe (44) is contacted thereby and forged to produce the premium coupling blank (20). In a preferred embodiment, each of the horizontal hydraulic presses (84) is capable of applying a press force of at least about 75 tons (about 68 tonnes).
Further, each of the horizontal hydraulic presses (84) preferably applies a substantially identical press force as the press dies (68, 70) are reciprocated towards and away from each other. As well, the first and second press dies (68, 70) are preferably moved or reciprocated simultaneously or concurrently at a substantially similar speed or rate of movement.
Simultaneous or concurrent movement of the first and second press dies (68, 70) towards each other to extend within the holding cavity (66) with a substantially similar force and at a substantially similar speed produces the premium coupling blank (20) in a relatively central position within the holding cavity (66) between the first and second ends (62, 64) of the holding die assembly (58). Simultaneous or concurrent movement of the first and second press dies (68, 70) away from each other to withdraw from the holding cavity (66) with a substantially similar force and at a substantially similar speed facilitates the release of the premium coupling blank (20) by the press dies (68, 70) and tends to maintain the premium coupling blank (20) in the relatively central position within the holding cavity (66).
In some embodiments, the holding die assembly (58) may then be moved to the open position for removal of the premium coupling blank (20) from the forging apparatus (56). Otherwise, the premium coupling blank (20) may need to be dislodged from the holding cavity (66).
In order to reduce wear on the press die apparatus (56), and to enhance the efficiency of the forging apparatus (56) and method, the tubular pipe (44) is preferably heated prior to forging such that the tubular pipe (44) undergoes hot forging, as compared to cold forging. Hot and relatively slow forging of the tubular pipe (44) permits the hydraulic presses (82, 84) to operate at a tonnage as low as about 75 tons. Thus, the forging temperature is selected depending upon various factors including the desire to maximize the quality of the forged product, to reduce wear of the forging apparatus (56) and to enhance the efficiency of the forging method.
Referring to FIG. 5, in some of the embodiments of the forging apparatus (56) in which the holding die assembly (58) is comprised of the first and second holding dies (72, 74), the holding die assembly (58) is further comprised of a first end retainer (86) and a second end retainer (88). The first and second end retainers (86, 88) act, at least in part, to maintain or assist in maintaining the premium coupling blank (20) in the holding cavity (66) during the withdrawal of the first and second press dies (68, 70) from the holding cavity (66). As a result, the first and second end retainers (86, 88) facilitate the release of the premium coupling blank (20) by the first and second press dies (68, 70).
As shown in FIG. 5, the first end retainer (86) preferably projects into the holding cavity (66) adjacent to the first end (62) of the holding die assembly (58). The second end retainer (88) similarly preferably projects into the holding cavity (66) adjacent to the second end (64) of the holding die assembly (58). Each of the first end retainer (86) and the second retainer (88) is associated with both of the first holding die (72) and the second holding die (74).
In particular, the first holding die (72) includes a first retainer member (90) adjacent to the first end (62) of the holding die assembly (58). Similarly, the second holding die (74) includes a first retainer member (92) adjacent to the first end (62) of the holding die assembly (58), which is compatible with the first retainer member (90) of the first holding die (72). Thus, the first end retainer (86) is comprised of the first retainer members (90, 92) of the first and second holding dies (72, 74) respectively.
As well, the first holding die (72) includes a second retainer member (94) adjacent to the second end (64) of the holding die assembly (58). Similarly, the second holding die (74) includes a second retainer member (96) adjacent to the second end (64) of the holding die assembly(58), which is compatible with the second retainer member (94) of the first holding die (72). Thus, the second end retainer (88) is comprised of the second retainer members (94, 96) of the first and second holding dies (72, 74) respectively.
Each of the first retainer members (90, 92) and each of the second retainer members (94, 96) is comprised of a projection or protrusion extending into the holding cavity (66) and adapted to abut against or otherwise engage the premium coupling blank (20) positioned in the holding cavity (66). The projection may have any dimensions and configuration suitable for performing its intended function as described herein. However, preferably, each of the first end retainer (86) and the second end retainer (88) projects into the holding cavity (66) along a set of arcs that, in sum, are substantially about the circumference of the holding cavity (66) and that are approximately evenly spaced about such circumference. Further, preferably, the set of arcs are no deeper than the minimum wall thickness (36) of the premium coupling blank (20). In a preferred embodiment, each of the first end retainer (86) and the second end retainer (88) projects into the holding cavity (66) substantially about the complete circumference or inner dimension of the holding cavity (66).
Accordingly, as the first press die (68) is withdrawn from the holding cavity (66), the first end (28) of the premium coupling blank (20) abuts against and engages the first end retainer (86) and is inhibited from movement with, or being drawn along by, the first press die (68). Similarly, as the second press die (70) is withdrawn from the holding cavity (66), the second end (30) of the premium coupling blank (20) abuts against and engages the second end retainer (88) and is inhibited from movement with, or being drawn along by, the second press die (70). Thus, the premium coupling blank (20) is retained in a substantially central position within the holding cavity (66).
The invention is also directed at a forging method for forging the forging stock into the forged product, and is preferably performed or carried out utilizing the forging apparatus (56). Thus, the forging method comprises providing the holding die assembly (58) and positioning the tubular pipe (44) in the holding cavity (66). For instance, referring to FIG. 6, the tubular pipe (44) may simply be inserted through one of the first or second ends (62, 64) of the holding die assembly (58) into the holding cavity (66).
However, referring to FIGS. 3 and 4, the tubular pipe (44) is preferably positioned between the first and second holding dies (72, 74) when the holding die assembly (58) is in the open position. In this embodiment, the method further includes moving the first and second holding dies (72, 74) relatively toward each other to the closed position of the holding die assembly (58) such that the tubular pipe (44) is positioned within the holding cavity (66).
Relatively moving the first and second holding dies (72, 74) may be performed in any manner and by any process capable of achieving the closed position of the holding die assembly (58). Preferably, the method includes maintaining one of the first holding die (72) and the second holding die (74) in a fixed position while moving the other of the first holding die (72) and the second holding die (74). Referring to FIGS. 3 and 4, in a preferred embodiment, the second holding die (74) is moved in a substantially vertical direction or in a substantially vertical plane towards the fixed first holding die (72) by the vertical hydraulic press (82). Alternately, the first and second holding dies (72, 74) may be moved simultaneously or concurrently towards each other to the closed position.
Further, the method includes providing the press die apparatus (60), and particularly the first and second press dies (68, 70). Once the tubular pipe (44) is positioned in the holding cavity (66), the first and second press dies (68, 70) are moved relatively towards each other, to the closed position of the press die apparatus (60), in order to forge the tubular pipe (44) to produce the premium coupling blank (20).
Relatively moving the first and second press dies (68, 70) may be performed in any manner and by any process capable of achieving the closed position of the press die apparatus (60). For instance, referring to FIG. 6, the method may include maintaining one of the first and second press dies (68, 70) in a fixed position while moving the other of the first and second press dies (68, 70). However, preferably, referring to FIGS. 3 and 4, the first and second press dies (68, 70) are moved simultaneously or concurrently to the closed position.
Referring to FIGS. 3 and 4, in a preferred embodiment, the method comprises extending the first press die (68) within the holding cavity (66) from the first end (62) of the holding die assembly (58) and extending the second press die (70) within the holding cavity (66) from the second end (64) of the holding die assembly (58) in order to forge the tubular pipe (44) positioned within the holding cavity (66).
Extending the first press die (68) and extending the second press die (70) are conducted or performed concurrently or simultaneously. More particularly, the first and second press dies (68, 70) are concurrently or simultaneously moved towards each other, at substantially similar speeds and applying substantially similar press forces, in a substantially horizontal direction or along a substantially horizontal axis by the horizontal hydraulic presses (84). Thus, the pressure exerted on the tubular pipe (44) by the first and second press dies (68, 70) is applied equally and evenly such that the deformation of the tubular pipe (44) may be controlled to produce the desired premium coupling blank (20).
Once the tubular pipe (44) is forged, the first and second press dies (68, 70) are moved relatively away from each other, to the open position of the press die apparatus (60). Relatively moving the first and second press dies (68, 70) away from each other may be performed in any manner and by any process capable of achieving the open position of the press die apparatus (60). For instance, referring to FIG. 6, the method may include maintaining one of the first and second press dies (68, 70) in a fixed position while moving the other of the first and second press dies (68, 70). However, preferably, referring to FIGS. 3 and 4, the first and second press dies (68, 70) arc moved simultaneously or concurrently away from each other to the open position.
Referring to FIGS. 3 and 4, in a preferred embodiment, the method comprises withdrawing the first press die (68) from the holding cavity (66) from the first end (62) of the holding die assembly (58) and withdrawing the second press die (70) from the holding cavity (66) from the second end (64) of the holding die assembly (58), while maintaining the holding die assembly (58) in the closed position. Withdrawing the first press die (68) and withdrawing the second press die (70) are conducted or performed concurrently or simultaneously. More particularly, the first and second press dies (68, 70) are concurrently or simultaneously moved away from each other, at substantially similar speeds and applying substantially similar withdrawal forces, in a substantially horizontal direction or along a substantially horizontal axis by the horizontal hydraulic presses (84).
The forged premium coupling blank (20) is then removed from the holding cavity (66). If necessary, removing the premium coupling blank (20) may include dislodging the premium coupling blank (20) from the holding cavity (66). The premium coupling blank (20) may be dislodged, released or “loosened” from the holding cavity (66) to facilitate its removal from the holding die assembly (58) in any manner or by any method or mechanism. For instance, in some embodiments, a “knockout” mechanism (98), as shown in FIG. 6, may be utilized. The knockout mechanism (98) is of particular use where the holding die assembly (58) is comprised of a single or unitary component, such that the holding die assembly (58) is not movable to an open position.
In the preferred embodiment, the holding die assembly (58) includes the first and second holding dies (72, 74). Accordingly, prior to removing the premium coupling blank (20), the method includes relatively moving the first and second holding dies (72, 74) away from each other to the open position of the holding die assembly (58). The method then includes removing the premium coupling blank (20) from the holding cavity (66) while the holding die assembly (58) is in the open position.
Relatively moving the first and second holding dies (72, 74) away from each other may be performed in any manner and by any process capable of achieving the open position of the holding die assembly (58). Preferably, the method includes maintaining one of the first and second holding dies (72, 74) in a fixed position while moving the other of the first and second holding dies (72, 74). Referring to FIGS. 3 and 4, in a preferred embodiment, the second holding die (74) is moved in a substantially vertical direction or in a substantially vertical plane away from the fixed first holding die (72) by the vertical hydraulic press (82). Alternately, the first and second holding dies (72, 74) may be moved simultaneously or concurrently away from each other to the open position.
Preferably, the premium coupling blank (20) is retained in the holding cavity (66) during the withdrawal of the first and second press dies (68, 70). If withdrawal of the first and second press dies (68, 70) is concurrent or simultaneous, this fact alone may suffice to cause the premium coupling blank (20) to be retained in the holding cavity (66). However, where required, the method may further include actively retaining the premium coupling blank (20) in the holding cavity (66) while relatively moving the first and second press dies (68, 70) away from each other or while withdrawing one or both of the first and second press dies (68, 70) from the holding cavity (66). Retaining the forged product may be performed in any manner or by any method capable of inhibiting or preventing the movement of the forged product within the holding cavity (66).
For instance, as shown in FIGS. 3 and 4, where the holding die assembly (58) includes the first and second holding dies (72, 74), retaining the premium coupling blank (20) may be comprised of gripping the premium coupling blank (20) between the first and second holding dies (72, 74). A sufficient gripping force may be applied to the premium coupling blank (20) to inhibit or prevent the movement of the premium coupling blank (20) relative to the first and second holding dies (72, 74).
However, retaining the premium coupling blank (20) in the holding cavity (66) is preferably comprised of engaging the premium coupling blank (20) with at least one, and preferably both, of the first end retainer (86) and the second end retainer (88). More particularly, referring to FIG. 5, retaining the premium coupling blank (20) in the holding cavity (66) is comprised of engaging the first end (28) of the premium coupling blank (20) with the first end retainer (86), preferably by abutting the first retainer members (90, 92) against or with the first end (28) of the premium coupling blank (20). In addition, retaining the premium coupling blank (20) in the holding cavity (66) is further comprised of engaging the second end (30) of the premium coupling blank (20) with the second end retainer (88), preferably by abutting the second retainer members (94, 96) against or with the second end (30) of the premium coupling blank (20).
The forging apparatus (56) preferably permits the forged product to be removed from the forging apparatus (56) in a relatively easy or efficient manner. In a preferred embodiment, this is achieved by providing the holding die assembly (58) with the first and second holding dies (72, 74) and moving them to the open position. However, in some embodiments, the holding die assembly (58) is comprised of a single component or unitary holding die which is not movable to an open position. In such embodiments, a knockout mechanism (98) is preferably provided for dislodging the premium coupling blank (20) from the holding cavity (66) such that the premium coupling blank (20) may be more easily or readily removed from the holding die assembly (58).
Referring to FIG. 6, the forging apparatus (56) is comprised of a holding die assembly (58) which is not adapted or configured to be movable to an open position. Further, the press die apparatus (60) is comprised of the first and second press dies (68, 70), which are movable relative to each other. During the forging method, the first or bottom press die (68) is fixed or stationary, while the second or top press die (70) moves towards the first press die (68), within the holding cavity (66) to forge the tubular pipe (44) and produce the premium coupling blank (20). Following the forging operation, the second press die (70) is relatively moved away from the first press die (68), resulting in the withdrawal of the second press die (70) from the holding cavity (66).
Typically, upon withdrawal of the second press die (70) and movement to the open position of the press die apparatus (60), the premium coupling blank (20) tends to remain within the holding cavity (66). The knockout mechanism (98) is provided for exerting a force on the premium coupling blank (20) causing the premium coupling blank (20) to move within the holding cavity (66) relative to the holding die assembly (58). Preferably, where the forging apparatus (56) is configured as shown in FIG. 6, an upward, vertically directed force is applied to the premium coupling blank (20) such that the premium coupling bank (20) is removable from the holding cavity (66) from the second or top end (64) of the holding die assembly (58).
FIG. 6 depicts a preferred embodiment of the knockout mechanism (98). The holding die assembly (58) is substantially vertically oriented such that the first end (62) is contacted with and supported in the desired position on a holding die assembly supporting surface (100) of the forging apparatus (56), which may be referred to as the “work table.”
Further, the knockout mechanism (98) comprises a dislodging or knockout plate (102) which is inserted within the holding cavity (66), preferably adjacent the first end (62) of the holding die assembly (58). The dislodging plate (102) has a first or lower surface (104) and an opposed second or upper surface (106).
The second or upper surface (106) of the dislodging plate (102) is configured to engage the forged product, preferably the first end (28) of the premium coupling blank (20), when the dislodging plate (102) is inserted in the holding cavity (66). Further, the second or upper surface (106) of the dislodging plate (102) defines a recess (107) therein which is configured to be compatible with the first or bottom press die (68) such that the first press die (68) may be received within the recess (107) of the second surface (106) of the dislodging plate (102), as described further below.
The first or lower surface (104) of the dislodging plate (102) is configured to be supportable upon the supporting surface (100). In addition, the first surface (104) defines a recess (108) for receiving a compatible lifting or knockout bar (110), as discussed further below.
As shown in FIG. 6, during the forging operation to produce the forged product, the first surface (104) of the dislodging plate (102) is supported upon the supporting surface (100). Further, the first press die (68) is preferably supported within the recess (107) a spaced distance from the second surface (106) of the dislodging plate (102). For this purpose, at least one lift block (112) is preferably provided to support the first press die (68) in the desired position within the recess (107). The lift block (112) is provided, at least in part, to absorb a portion of the pressure exerted on the first press die (68) during the forging process. Although any type of lift block (112) or other lifting or spacing structure capable of absorbing the desired forces of the press die apparatus (60) may be used, the lift block (112) preferably passes through the dislodging plate (102) to extend between the supporting surface (100) and the first press die (68) and is of a sufficient length to support the first press die (68) the desired distance from the second surface (106) of the dislodging plate (102). In the preferred embodiment, the lift block (112) is fixed to the supporting surface (100) and the dislodging plate (102) is slidably movable on the lift block (112) to permit the movement of the dislodging plate (102) relative to the lift block (112).
As indicated, the knockout mechanism (98) is further comprised of the lifting bar (110). The lifting bar (110) is received within the recess (108) on the first surface (104) of the dislodging plate (102) such that movement of the lifting bar (110) in the direction of the dislodging plate (102) results in a corresponding movement of the dislodging plate (102). Preferably, the movement of the lifting bar (110) towards the dislodging plate (102) is provided in a substantially vertical direction, resulting in a substantially vertical movement of the dislodging plate (102). The lifting bar (110) may be mechanically, electrically or hydraulically actuated to move in the direction of the dislodging plate (102) by any suitable mechanism or structure capable of providing the required or desired lifting force to achieve the purposes described herein. In the preferred embodiment of FIG. 6, the knockout mechanism (98) includes at least one hydraulic cylinder (114), operatively connected with the lifting bar (110), for hydraulically actuating the lifting bar (110) to move.
In operation, following the forging of the forged product, the second press die (70) is removed or withdrawn from the holding cavity (66), in a manner as described previously, such as by actuation of the hydraulic press (84). Subsequently, the hydraulic cylinder (114) actuates the lifting bar (110) to move upwards, or in the direction of the dislodging plate (102). As a result, the dislodging plate (102) is moved upwardly within the holding cavity (66), in a direction away from the first end (62) of the holding die assembly (58) and towards the second end (64). The engagement of the second surface (106) of the dislodging plate (102) with the first end (28) of the premium coupling blank (20) causes the premium coupling blank (20) to correspondingly move within the holding cavity (66).
Thus, the movement of the dislodging plate (102) causes the premium coupling blank (20) to be dislodged or released from the holding die assembly (58). However, typically, the first press die (68) moves with the premium coupling blank (20) as the premium coupling blank (20) is moved or lifted by the dislodging plate (102). Therefore, once the premium coupling blank (20) is dislodged from the holding cavity (66), further movement of the dislodging plate (102) ceases. A rod (116) is then inserted, either manually or preferably automatically, within the holding cavity (66) from the second end (64) of the holding die assembly (58).
More particularly, as shown in FIG. 6, one end of the rod (116) is preferably abutted against the first press die (68). Subsequently, the premium coupling blank (20) may be dislodged or released from the first press die (68) either by moving the rod (116) and the first press die (68) while maintaining the position of the premium coupling blank (20) or by moving the premium coupling blank (20) while maintaining the positions of the rod (116) and the first press die (68).
In the first instance, movement of the rod (116) in the direction of the first end (62) of the holding die assembly (58) applies a force to the first press die (68) which causes a corresponding movement of the first press die (68). As a result of the engagement of the premium coupling blank (20) with the dislodging plate (102), movement of the first press die (68) towards the first end (62) of the holding die assembly (58) causes the premium coupling blank (20) to be dislodged or released from the first press die (68). The first press die (68) is then received within the recess (107) of the second surface (106) of the dislodging plate (102) and further movement of the rod (116) ceases.
The force may be applied to the rod (116) to move the rod (116) and dislodge the first press die (68) in any manner and by any mechanism or structure capable of applying the required force. However, preferably, as shown in FIG. 6, following the abutment of one end of the rod (116) against the first press die (68), the second press die (70) is brought into engagement with the other end of the rod (116). Thus, the force may be applied to the rod (116) through the actuation of the second press die (70), such as by the hydraulic press (84).
In the alternative instance, further movement of the dislodging plate (102) in the direction of the second end (64) of the holding die assembly (58) causes a corresponding movement of the premium coupling blank (20) as a result of the engagement of the premium coupling blank (20) with the dislodging plate (102). The rod (116) prevents or inhibits a corresponding movement of the first press die (68), resulting in the dislodging or release of the premium coupling blank (20) from the first press die (68). Once the first press die (68) is received within the recess (107) of the second surface (106) of the dislodging plate (102), further movement of the dislodging plate (102) ceases.
Once the premium coupling blank (20) is dislodged from both the holding die assembly (58) and the first press die (68), the second press die (70) or the dislodging plate (102), as the case may be, is retracted sufficiently to permit the removal of the rod (116), and the rod (116) is removed. The dislodging plate (102) is then further moved in a direction towards the second end (64) of the holding die assembly (58), causing a corresponding movement of the premium coupling blank (20). When the premium coupling blank (20) is lifted sufficiently within the holding cavity (66), the premium coupling blank (20) may be removed form the forging apparatus (56).
Referring to FIGS. 7-10, in further embodiments of the forging apparatus (56) and forging method, the forging apparatus (56) may include a finning control mechanism (118) and the method may include controlling “finning” or “heading” between the first and second press dies (68, 70) while the forged product is being produced. More particularly, “finning” refers to the seepage of material into the press die gap. Finning is particularly undesirable if such seepage causes the wall thickness of the forged product (20) to exceed the desired maximum wall thickness (38) and/or to fall below a desired outside diameter. The method for controlling finning is preferably performed utilizing the finning control mechanism (118) described herein.
Due to the redistribution of the material of the tubular pipe (44) during forging, a potential exists for undesired “finning”, “heading” or “upsetting” to form between the first and second press dies (68, 70) as they are moved toward each other. Referring to FIG. 7, examples of potential undesirable “finning” of the tubular pipe (44) between the first and second press dies (68, 70) are shown. The first press die (68) and the second press die (70) define a variable press die gap (120) between them as they relatively move toward and away from each other, or as they extend within and withdraw from the holding cavity (66). Finning of the material of the tubular pipe (44) occurs when a portion of the material of the tubular pipe (44) extrudes into the variable press die gap (120) as the first and second press dies (68, 70) move together within the holding cavity (66). The material extruded within the variable press die gap (120) forms a “fin” (122), “head” or “upset”, which prevents the first and second press dies (68, 70) from engaging each other within the holding cavity (66).
Finning is undesirable in the production of the premium coupling blank (20) as it may result in the shortage of material from the tubular pipe (44) to produce a premium coupling blank (20) of the desired shape or configuration. Further, subsequent machining of the forged premium coupling blank (20) may be impeded or rendered more difficult by the presence of the fin (122). It has been found that finning is more prevalent where the tubular pipe (44) is comprised of a standard API coupling blank or where the wall thickness and/or the length of the tubular pipe (44) is insufficient. However, finning is less prevalent where the tubular pipe (44) is-comprised of a standard tubing blank or where the wall thickness and the length of the tubular pipe (44) is sufficient In this instance, a finning control mechanism (118) may not be required.
Referring to FIGS. 8-10, the finning control mechanism (118) is preferably comprised of a variable spanning device (124) for spanning or extending across the press die gap (120), throughout all or part of the range of the press die gap (120), between the first and second press dies (68, 70). Specifically, the variable spanning device (124) preferably crosses and “fills” the variable press die gap (120) as the first and second press dies (68, 70) are moving toward each other in order to prevent or inhibit the extrusion of material into the gap (120). For instance, a central portion or center part of each press die (68, 70) preferably extends toward the other when the press dies (68, 70) are not fully abutted or are not in the closed position of the press die apparatus (60). Upon engagement or abutment of the central portions, the central portions are capable of retraction in order to permit the press dies (68, 70) to be further moved together to the closed position of the press die apparatus (60).
The particular structure of the finning control mechanism (118) described herein also permits the forging apparatus (56) to more readily adjust to or accommodate different or varying lengths of the tubular pipe (44). For instance, the extension of the central portions of each press die (68, 70) will permit the press die apparatus (60) to accommodate a longer length of tubular pipe (44). In this case, any excess material of the tubular pipe (44) will tend to be added to the premium coupling blank (20) at its length.
Preferably, the variable spanning device (124) is comprised of an inner die telescopically or slidably received within one, and more preferably both, of the first press die (68) and the second press die (70). As a result, the inner die is capable of reciprocable movement relative to the respective press die (68, 70) in order to extend or retract therefrom.
In the preferred embodiment of the variable spanning device (124), a first inner die (126) is telescopically received within the first press die (68) and a second inner die (128) is telescopically received within the second press die (70). Each of the first and second inner dies (126, 128) is capable of reciprocable movement relative to the first and second press dies (68, 70) respectively between an extended position and a retracted position. The first and second inner dies (126, 128) are configured or adapted to engage or abut each other throughout an appropriate or required range of the variable press die gap (120) in order to control or limit any potential finning therebetween. Specifically, the first and second inner dies (126, 128) preferably engage or abut each other to span the press die gap (120) at an appropriate location or point before the first and second press dies (68, 70) reach their extended positions within the holding cavity (66).
Referring to FIGS. 8 and 9, in one embodiment of the finning control mechanism (118), at least one, and preferably both, of the first inner die (126) and the second inner die (128) is biased toward the extended position. Thus, each of the first and second inner dies (126, 128) is movable to the retracted position by overcoming the bias. As shown in detail in FIG. 9, each inner die (126, 128) is slidably received within its respective press die (68, 70). Each inner die (126, 128) has an outer end (130) configured for abutment or engagement with the outer end (130) of the other inner die (126, 128) as described above. The inner dies (126, 128) may comprise guide pins (not shown) to assist the alignment of the inner dies (126, 128) with respect to the holding cavity (66). Further, each inner die (126, 128) has an opposed inner end (132) configured and adapted for contact with a biasing mechanism for urging the inner die (126, 128) towards its extended position.
As well, the inner end (132) is preferably configured or adapted to inhibit or prevent the movement of the inner die (126, 128) out of the press die (68, 70). In other words, the inner end (132) provides a mechanism for retaining the inner die (126, 128) within the press die (68, 70) when moved to its fully extended position. For instance, the inner end (132) of each of the first and second inner dies (126, 128) may include a shoulder (136) for engaging a compatible shoulder (138) defined by the respective press die (68, 70), as shown in FIG. 9. Any alternate retaining mechanism may be utilized which is capable of preventing or inhibiting the removal of the inner die (126, 128) from the press die (68, 70).
Each biasing mechanism provides a biasing force sufficient to urge the inner die (126, 128) toward its extended position, and preferably to move the inner die (126, 128) to the fully extended position, while also permitting movement of the inner die (126, 128) toward the retracted position. The particular biasing mechanism will be selected based, at least in part, upon the anticipated press forces to be applied by the press die apparatus (60). In a preferred embodiment, a first biasing mechanism (134) is provided for biasing the first inner die (126) toward the extended position and a second biasing mechanism (135) is provided for biasing the second inner die (128) toward the extended position. Preferably, each of the first and second biasing mechanisms (134, 135) is comprised of a spring extending between the inner end (132) of the inner die (126, 128) and a support block (140) configured to receive and support an end of the spring therein. In some embodiments, the pressure which is built up during the forging operation inside the biasing mechanism (134, 135) may be sufficient enough to replace the function of the springs.
Referring to FIGS. 8( a), 8(b) and 8(c), the forging method, including the method for controlling finning, is shown in sequence using the finning control mechanism (118) of FIG. 9. As shown in FIG. 8( a), in both the open position of the holding die assembly (58) and the open position of the press die apparatus (60), the tubular pipe (44) is placed in the holding cavity (66). Further, the inner die (126, 128) of each of the press dies (68, 70) is in the extended position.
Referring to FIG. 8( b), the holding die assembly (58) and the press die apparatus (60) are moved to their respective closed positions. As the first and second press dies (68, 70) are extended within the holding cavity (66), the first and second inner dies (126, 128) span the variable press die gap (120) and engage each other. Upon further movement of the press die apparatus (60) toward the closed position, the first and second inner dies (126, 128) are moved toward their respective retracted positions, as shown in FIG. 8( b). Finally, referring to FIG. 8( c), following the production of the forged product, the holding die assembly (58) and the press die apparatus (60) are returned to their respective open positions, and the inner die (126, 128) of each of the press dies (68, 70) is returned to its extended position.
Referring to FIG. 10, in an alternate preferred embodiment of the finning control mechanism (118), at least one, and preferably both, of the first inner die (126) and the second inner die (128) is actuatable toward the extended position. As described previously, each inner die (126, 128) is slidably received within its respective press die (68, 70). Each inner die (126, 128) has an outer end (130) configured for abutment or engagement with the outer end (130) of the other inner die (126, 128) as described above. Further, each inner die (126, 128) has an opposed inner end (132) configured and adapted for engagement with or contact by an actuator (142) for moving or actuating the inner die (126, 128) towards its extended position.
The actuator (142) may be comprised of any mechanical, hydraulic or electrical mechanism, device or structure capable of actuating the respective inner die (126, 128) to move towards its extended position. Preferably, the actuator (142) is hydraulically actuated. Referring to FIG. 10, the actuator (142) is comprised of an inner punch assembly (144). In addition, the actuator (142) may also be comprised of an outer punch assembly (146). The inner punch assembly (144) is associated with the respective inner die (126, 128) for causing the inner die (126, 128) to move to the extended position. The outer punch assembly (146) is associated with the respective press die (68, 70) for causing the press die (68, 70) to be extended to forge the tubular pipe (44).
More particularly, the inner punch assembly (144) includes a movable or reciprocable shaft, preferably an inner shaft (148) having a first end (150) and a second end (152). The first end (150) of the inner shaft (148) is associated with, and preferably connected, fastened or otherwise affixed with, the inner end (132) of the respective inner die (126, 128) such that reciprocation of the inner shaft (148) results in the reciprocation of the inner die (126, 128). The second end (152) of the shaft (148) is associated with a hydraulic chamber (154), and preferably is contained within the hydraulic chamber (154).
More preferably, the hydraulic chamber (154) is configured or adapted to permit a fluid communicated to the hydraulic chamber (154) to act upon the second end (152). The second end (152) of the inner shaft (148) is also preferably configured or adapted to facilitate or enhance the effect or action of the fluid on the second end (152). For instance, the second end (152) may be shaped or configured as a disklike structure or a disk-shaped structure with a seal for movement within the compatible hydraulic chamber (154) to provide a piston effect. Preferably, the fluid acts upon the second end (152) within the hydraulic chamber (154) to actuate the inner shaft (148) to reciprocate in a first direction to move the inner die (126, 128) to its extended position. If desired, the fluid may further alternately act upon the second end (152) within the hydraulic chamber (154) to actuate the shaft (148) to reciprocate in an opposed second direction to move the inner die (126, 128) to its retracted position.
As well, the hydraulic chamber (154) may be configured to limit the movement of the inner shaft (148) therein to provide a desired range of travel of the inner shaft (148). Specifically, the second end (152) of the inner shaft (148) may be configured to abut an end of the hydraulic chamber (154) to limit the movement in the first direction. Similarly, the second end (152) of the inner shaft (148) may be configured to abut an opposed end of the hydraulic chamber (154) to limit the movement in the second direction. If desired, one or more dampening or shock absorbing mechanisms, such as a spring (156), may be associated with the hydraulic chamber (154) at either or each end thereof such that the second end (152) abuts the spring (156) as it moves to the end of the desired range of travel within the hydraulic chamber (154) in either or both directions.
The outer punch assembly (146) similarly includes a movable or reciprocable shaft, preferably a cylindrical outer shaft (158) having a first end (160) and a second end (162). The first end (160) of the outer shaft (158) is associated with, and preferably connected, fastened or otherwise affixed with, the respective press die (68, 70) such that reciprocation of the outer shaft (158) results in the reciprocation or movement of the press die (68, 70). The second end (162) of the outer shaft (158) is associated with a hydraulic chamber (164), and preferably is contained within the hydraulic chamber (164).
Although the inner and outer punch assemblies (144, 146) may be arranged relative to each other in any manner, preferably, as shown in FIG. 10, the inner shaft (148) of the inner punch assembly (144) extends or passes through the outer punch assembly (146) for connection with the inner die (126, 128). More particularly, the inner shaft (148) of the inner punch assembly (144) extends or passes through both the outer shaft (158) and the hydraulic chamber (164) of the outer punch assembly (146). Further, the outer shaft (158) and the hydraulic chamber (164) of the outer punch assembly (146) are configured to permit the inner shaft (148) of the inner punch assembly (144) to pass through them and to permit the inner die (126, 128) to pass therethrough to its respective extended position.
Further, the hydraulic chamber (164) of the outer punch assembly (146) is also configured or adapted to permit a fluid communicated to the hydraulic chamber (164) to act upon the second end (162) of the outer shaft (158). The second end (162) of the outer shaft (158) is preferably configured or adapted to facilitate or enhance the effect or action of the fluid on the second end (162). For instance, the second end (162) may also be shaped or configured as a disk-like structure or an annulus-shaped structure with a seal for movement within the compatible hydraulic chamber (164) to provide a piston effect. Preferably, the fluid acts upon the second end (162) within the hydraulic chamber (164) to actuate the outer shaft (158) to reciprocate in a first direction to extend the respective press die (68, 70) within the holding cavity (66). If desired, the fluid may further alternately act upon the second end (162) within the hydraulic chamber (164) to actuate the outer shaft (158) to reciprocate in an opposed second direction to withdraw the press die (68, 70) from the holding cavity (66).
The hydraulic chamber (164) may be configured to limit the movement of the outer shaft (158) therein to provide a desired range of travel of the outre shaft (158). Specifically, the second end (162) of the outer shaft (158) may be configured to abut an end of the hydraulic chamber (164) to limit the movement in the first direction. Similarly, the second end (162) of the outer shaft (158) may be configured to abut an opposed end of the hydraulic chamber (164) to limit the movement in the second direction. If desired, one or more dampening or shock absorbing mechanisms, such as a spring (166), may be associated with the hydraulic chamber (164) at either or each end thereof such that the second end (162) abuts the spring (166) as it moves to the end of the desired range of travel within the hydraulic chamber (154) in either or both directions.
In operation, referring to FIG. 10, following the movement of the holding die assembly (58) to the closed position, the inner punch assembly (144) of each press die (68, 70) is hydraulically actuated to move the inner shaft (148) in the first direction and thus move the respective inner die (126, 128) toward the extended position. Subsequent thereto or simultaneously therewith, the outer punch assembly (146) is hydraulically actuated to move the outer shaft (158) in the first direction and thus extend the respective press die (68, 70) within the holding cavity (66). The actuations of the inner punch assembly (144) and the outer punch assembly (146) are coordinated so that the inner dies (126, 128) reach their extended positions before the shifting of the material of the tubular pipe (44) progresses to the point at which “finning” could occur.
Following the forging of the tubular pipe (44) within the holding cavity (66), the inner punch assembly (144) is released. In other words, release of the hydraulic pressure within the hydraulic chamber (154) permits the inner shaft (148) to move in the second direction and thus move the respective inner die (126, 128) to the retracted position. Alternately, the inner shaft (148) may be actively moved or actuated in the second direction. Similarly, the outer punch assembly (146) is released. In other words, release of the hydraulic pressure within the hydraulic chamber (164) permits the outer shaft (158) to move in the second direction and thus withdraw the respective press die (68, 70) from the holding cavity (66). Alternately, the outer shaft (158) may be actively moved or actuated in the second direction. Also, the holding assembly (58) is moved to the open position.
Thus, there are preferably three steps to be performed to release the premium coupling blank (20) from the forging apparatus (56) after forging, which steps may be performed in various orders, any of which may be appropriate in certain modes of operation. However, in the typical or preferred mode of operation of the forging method described herein, the preferred order of the method steps is, first, retraction of the inner dies (126, 128), second, withdrawal of the press dies (68, 70) and, third, movement of the holding die assembly (58) to the open position.
Once the premium coupling blank (20) is produced by the forging method and forging apparatus (56) as described herein, the premium coupling blank (20) is preferably subjected to further treating in order to achieve the desired or required material specifications of the premium coupling blank (20). Specifically, the premium coupling blank (20) is preferably subjected to heat treating. Heat treating is required to provide a premium coupling blank (20) suitable for later production of, and intended use as, a premium coupling (22) for a particular application, such as an OCTG premium coupling.
The heat treating is conducted according to known heat treating techniques and methods. Further, the particular heat treating technique or combination of techniques and the particular parameters of such heat treating techniques are selected such that the material properties of the premium coupling blank (20) may be altered thereby to provide a set of material properties which are suitable for use as the premium coupling (22). Thus, preferably, the heat treating techniques are selected to be suitable for use in heat treating metal components, particularly steel or stainless steel.
Preferably, heat treating of the forged product, preferably the premium coupling blank (20), is comprised of quenching and tempering, normalizing or annealing.
Austempering may be used as a substitute for conventional quenching and tempering. In this regard, austempering has been found to provide desirable cracking prevention properties, and may be more cost effective than conventional techniques in some applications.
However, where desired, any suitable heat treating technique or techniques may be utilized that are capable of producing the desired material properties of the premium coupling blank (20). For instance, heat treating techniques may include normalizing or annealing. In addition, other heat treating techniques may include quenching and/or tempering. The following examples are provided of potential heat treating of the premium coupling blank (20).
For example, OCTG API Grades H40, J55, K55, N80 Type 1, M65 are typically produced by no heat treating, normalizing or normalizing and tempering. However, some of these Grades may be produced by quenching and tempering. Further, in order to produce premium coupling blanks (20) of these Grades, the premium coupling blank (20) is preferably forged at the austenitizing temperature or the annealing temperature and slowly cooled. If the premium coupling blank (20) is forged at a temperature lower than the annealing temperature, the premium coupling blank (20) is preferably subjected to stress relief annealing or normalizing.
To provide material of OCTG API Grades N80 Type Q, L80 Type 1, L80 13Cr, L80 9Cr, C90 Type 1, C90 Type 2, C95, T95 Type 1, T95 Type 2, P110, Q125 Type 1, Q125 Type 2, Q125 Type 3 and Q125 Type 4, the premium coupling blank (20) is typically quenched and tempered. Further, as specified for OCTG API Grades, the preferable minimum tempering temperature for Grade L80 type 1 is 1050° F. (about 565.55° C.), for Grade L80 9Cr and Grade L80 13Cr is 1100° F. (about 593.33° C.), for Grade C90 type 1 and 2 is 1150° F. (about 621.11° C.), for Grade C95 is 1000° F. (about 537.78° C.) and for Grade T95 type 1 and 2 is 1200° F. (about 648.89° C.).
As well, in order to create premium coupling blanks (20) of these Grades, the premium coupling blank (20) may be forged at any predetermined temperature. If the premium coupling blank (20) is forged at the austenitizing temperature, the blank (20) could be quenched or normalized immediately following the forging. However, it is preferred that after the premium coupling blank (20) is forged, the blank (20) is reheated to be processed for heat treating. During the process, it is preferred that the residual heat from the forging be utilized.
Further, the austenitizing time is typically 1 hour per inch of wall thickness. In addition, a cooling rate is preferably provided of equal to or greater than about 100° F. (about 37.78° C.) per second (measured at 1300° F. or about 704.44° C.) in order to obtain a maximum amount of martensite, which is usually the preferred as-quenched steel composition.
Finally, referring to FIG. 11, a model is provided for the mass production of premium coupling blanks (20) using the present invention. Preferably, the production method is fully automated, such that one or more robot arms may be used to load and unload the work pieces. For instance, first, the forging stock, preferably the steel or stainless steel tubular pipe (44) as described herein, is heated in a heater (168), such as a conveyor induction heater, to a suitable forging temperature. The forging stock is then conducted to the forging apparatus (56) as described herein to produce the forged product, preferably the premium coupling blank (20).
The forged product may be subsequently subjected to an optional first annealing process, such as by subjecting it to a first annealing roller (170) for a suitable period of time. Specifically, the forged product may undergo the first roller annealing process for a period of 12 to 24 hours.
Next, the forged product is subjected to quenching in a quench integrated furnace (172) and tempering in a temper furnace (174). However, for more efficient production, a conveyor style furnace may also be applied as a heat treating method. Finally, the forged product may be subsequently subjected to an optional second annealing process, such as by subjecting it to a second annealing roller (176) for a suitable period of time. Specifically, the forged product may undergo the second roller annealing process for a period of 12 to 24 hours.
In this document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements.

Claims

1. A forging apparatus comprising:

(a) a holding die assembly having a first end and a second end and defining a holding cavity extending between the first end and the second end, the holding die assembly comprising a first holding die defining a first portion of the holding cavity and further comprising a second holding die opposed to the first holding die and defining a second portion of the holding cavity, wherein the first holding die and the second holding die are selectively relatively movable toward each other to a closed position of the holding die assembly and away from each other to an open position of the holding die assembly, and wherein the first holding die, the second holding die and the holding cavity are configured so that a forged product produced by the forging apparatus may be removed from the holding cavity when the holding die assembly is in the open position; and

(b) a press die apparatus comprising:

(i) a first press die which is selectively reciprocable in order to extend within and withdraw from the holding cavity from the first end of the holding die assembly; and

(ii) a second press die which is selectively reciprocable in order to extend within and withdraw from the holding cavity from the second end of the holding die assembly.

2. The forging apparatus as claimed in claim 1 wherein the holding die assembly is further comprised of a first end retainer which projects into the holding cavity adjacent to the first end of the holding die assembly and wherein the holding die assembly is further comprised of a second end retainer which projects into the holding cavity adjacent to the second end of the holding die assembly.

3. The forging apparatus as claimed in claim 2 wherein the first holding die is comprised of a retainer member adjacent to the first end of the holding die assembly and wherein the first end retainer is comprised of the retainer member.

4. The forging apparatus as claimed in claim 2 wherein the second holding die is comprised of a retainer member adjacent to the first end of the holding die assembly and wherein the first end retainer is comprised of the retainer member.

5. The forging apparatus as claimed in claim 2 wherein the first holding die is comprised of a retainer member adjacent to the second end of the holding die assembly and wherein the second end retainer is comprised of the retainer member.

6. The forging apparatus as claimed in claim 2 wherein the second holding die is comprised of a retainer member adjacent to the second end of the holding die assembly and wherein the second end retainer is comprised of the retainer member.

7. The forging apparatus as claimed in claim 2 wherein the first holding die is comprised of a retainer member adjacent to each of the first end and the second end of the holding die assembly, wherein the second holding die is comprised of a retainer member adjacent to each of the first end and the second end of the holding die assembly, and wherein the first end retainer and the second end retainer are comprised of the retainer members.

8. The forging apparatus as claimed in claim 1 wherein the first holding die and the second holding die define a holding die interface plane and wherein the holding die interface plane extends between the first end and the second end of the holding die assembly.

9. The forging apparatus as claimed in claim 1 wherein one of the first holding die and the second holding die is in a fixed position and wherein the other of the first holding die and the second holding die is movable.

10. The forging apparatus as claimed in claim 9 wherein the first holding die and the second holding die define a holding die interface plane and wherein the first holding die and the second holding die are configured so that the holding die interface plane is substantially horizontal.

11. The forging apparatus as claimed in claim 10 wherein the first holding die is a bottom holding die, wherein the second holding die is a top holding die, wherein the bottom holding die is fixed, and wherein the top holding die is movable.

12. The forging apparatus as claimed in claim 11 wherein the holding die interface plane extends between the first end and the second end of the holding die assembly.

13. The forging apparatus as claimed in claim 1 wherein the forging apparatus is configured to produce a premium coupling machining blank as the forged product.

14. The forging apparatus as claimed in claim 13 wherein the forging apparatus is configured to produce the premium coupling machining blank from a length of a tubular pipe as a forging stock, wherein the tubular pipe has a wall thickness, wherein the premium coupling machining blank has a maximum wall thickness, and wherein the wall thickness of the tubular pipe is less than the maximum wall thickness of the premium coupling machining blank.

15. The forging apparatus as claimed in claim 14 wherein the premium coupling machining blank has a minimum wall thickness and wherein the wall thickness of the tubular pipe is greater than the minimum wall thickness of the premium coupling machining blank.

16. The forging apparatus as claimed in claim 14 wherein the premium coupling machining blank has a length and wherein the length of the premium coupling machining blank is greater than the length of the tubular pipe.

17. The forging apparatus as claimed in claim 14, further comprising a finning control mechanism for controlling finning between the first press die and the second press die while the forged product is being produced by the forging apparatus.

18. The forging apparatus as claimed in claim 17 wherein the first press die and the second press die define a variable press die gap between them as they extend within and withdraw from the holding cavity and wherein the finning control mechanism is comprised of a variable spanning device for spanning the press die gap throughout a range of the press die gap.

19. The forging apparatus as claimed in claim 18 wherein the spanning device is comprised of an inner die telescopically received within a one of the first press die and the second press die such that the inner die is capable of reciprocable movement, relative to the one of the first press die and the second press die, between an extended position and a retracted position in order to span the press die gap throughout the range of the press die gap.

20. The forging apparatus as claimed in claim 19 wherein the inner die is biased toward the extended position and movable toward the retracted position by overcoming the bias.

21. The forging apparatus as claimed in claim 18 wherein the spanning device is comprised of a first inner die telescopically received within the first press die, wherein the first inner die is capable of reciprocable movement relative to the first press die between an extended position and a retracted position, wherein the spanning device is further comprised of a second inner die telescopically received within the second press die, and wherein the second inner die is capable of reciprocable movement relative to the second press die between an extended position and a retracted position.

22. The forging apparatus as claimed in claim 21 wherein the first inner die and the second inner die are adapted to engage each other as the first press die and the second press die are extended within the holding cavity in order to span the press die gap throughout the range of the press die gap.

23. The forging apparatus as claimed in claim 22 wherein the first inner die and the second inner die are each biased toward the extended position and movable toward the retracted position by overcoming the bias.

24. The forging apparatus as claimed in claim 23, further comprising a first biasing mechanism for biasing the first inner die toward the extended position and further comprising a second biasing mechanism for biasing the second inner die toward the extended position.

25. The forging apparatus as claimed in claim 22 wherein the first inner die and the second inner die are each actuatable toward the extended position.

26. The forging apparatus as claimed in claim 25 wherein the first inner die and the second inner die are each hydraulically actuatable toward the extended position.

27. A forging apparatus comprising:

(a) a holding die assembly having a first end and a second end and defining a holding cavity extending between the first end and the second end;

(b) a press die apparatus comprising a first press die and a second press die opposed to the first press die, wherein the first press die and the second press die are selectively relatively movable toward each other within the holding cavity to a closed position of the press die apparatus and away from each other to an open position of the press die apparatus; and

(c) a finning control mechanism for controlling finning between the first press die and the second press die while the forged product is being produced by the forging apparatus.

28. The forging apparatus as claimed in claim 27 wherein the first press die and the second press die define a variable press die gap between them as they relatively move toward and away from each other and wherein the finning control mechanism is comprised of a variable spanning device for spanning the press die gap throughout a range of the press die gap.

29. The forging apparatus as claimed in claim 28 wherein the spanning device is comprised of an inner die telescopically received within a one of the first press die and the second press die such that the inner die is capable of reciprocable movement, relative to the one of the first press die and the second press die, between an extended position and a retracted position in order to span the press die gap throughout the range of the press die gap.

30. The forging apparatus as claimed in claim 29 wherein the inner die is biased toward the extended position and movable toward the retracted position by overcoming the bias.

31. The forging apparatus as claimed in claim 28 wherein the spanning device is comprised of a first inner die telescopically received within the first press die, wherein the first inner die is capable of reciprocable movement relative to the first press die between an extended position and a retracted position, wherein the spanning device is further comprised of a second inner die telescopically received within the second press die, and wherein the second inner die is capable of reciprocable movement relative to the second press die between an extended position and a retracted position.

32. The forging apparatus as claimed in claim 31 wherein the first inner die and the second inner die are adapted to engage each other as the first press die and the second press die are extended within the holding cavity in order to span the press die gap throughout the range of the press die gap.

33. The forging apparatus as claimed in claim 32 wherein the first inner die and the second inner die are each biased toward the extended position and movable toward the retracted position by overcoming the bias.

34. The forging apparatus as claimed in claim 33, further comprising a first biasing mechanism for biasing the first inner die toward the extended position and further comprising a second biasing mechanism for biasing the second inner die toward the extended position.

35. The forging apparatus as claimed in claim 32 wherein the first inner die and the second inner die are each actuatable toward the extended position.

36. The forging apparatus as claimed in claim 35 wherein the first inner die and the second inner die are each hydraulically actuatable toward the extended position.

37. A forging method for forging a forging stock into a forged product, the forging method comprising:

(a) providing a holding die assembly having a first end and a second end and defining a holding cavity extending between the first end and the second end, the holding die assembly comprising a first holding die defining a first portion of the holding cavity and further comprising a second holding die opposed to the first holding die and defining a second portion of the holding cavity, wherein the first holding die and the second holding die are selectively relatively movable toward each other to a closed position of the holding die assembly and away from each other to an open position of the holding die assembly;

(b) positioning the forging stock between the first holding die and the second holding die when the holding die assembly is in the open position;

(c) relatively moving the first holding die and the second holding die toward each other to the closed position of the holding die assembly so that the forging stock is positioned in the holding cavity between the first holding die and the second holding die;

(d) providing a first press die which is selectively reciprocable in order to extend within and withdraw from the holding cavity from the first end of the holding die assembly, and providing a second press die which is selectively reciprocable in order to extend within and withdraw from the second end of the holding die assembly;

(e) extending the first press die within the holding cavity from the first end of the holding die assembly and extending the second press die within the holding cavity from the second end of the holding die assembly in order to forge the forging stock, thereby producing the forged product;

(f) withdrawing the first press die from the holding cavity from the first end of the holding die assembly and withdrawing the second press die from the holding cavity from the second end of the holding die assembly while maintaining the holding die assembly in the closed position;

(g) relatively moving the first holding die and the second holding die away from each other to the open position of the holding die assembly; and

(h) removing the forged product from the holding cavity while the holding die assembly is in the open position.

38. The forging method as claimed in claim 37, further comprising retaining the forged product in the holding cavity while withdrawing the first press die from the holding cavity and withdrawing the second press die from the holding cavity.

39. The forging method as claimed in claim 38 wherein retaining the forged product in the holding cavity is comprised of gripping the forged product between the first holding die and the second holding die.

40. The forging method as claimed in claim 38 wherein retaining the forged product in the holding cavity is comprised of engaging the forged product with a first end retainer associated with the first end of the holding die assembly.

41. The forging method as claimed in claim 38 wherein retaining the forged product in the holding cavity is comprised of engaging the forged product with a second end retainer associated with the second end of the holding die assembly.

42. The forging method as claimed in claim 40 wherein retaining the forged product in the holding cavity is further comprised of engaging the forged product with a second end retainer associated with the second end of the holding die assembly.

43. The forging method as claimed in claim 37 wherein the first holding die and the second holding die define a holding die interface plane and wherein the holding die interface plane extends between the first end and the second end of the holding die assembly.

44. The forging method as claimed in claim 37 wherein relatively moving the first holding die and the second holding die is comprised of maintaining one of the first holding die and the second holding die in a fixed position while moving the other of the first holding die and the second holding die.

45. The forging method as claimed in claim 44 wherein the first holding die and the second holding die define a holding die interface plane and wherein the first holding die and the second holding die are configured so that the holding die interface plane is substantially horizontal.

46. The forging method as claimed in claim 45 wherein the first holding die is a bottom holding die, wherein the second holding die is a top holding die, wherein the bottom holding die is maintained in the fixed position, and wherein the top holding die is movable.

47. The forging method as claimed in claim 46 wherein the holding die interface plane extends between the first end and the second end of the holding die assembly.

48. The forging method as claimed in claim 37 wherein the forged product is a premium coupling machining blank.

49. The forging method as claimed in claim 48 wherein the forging stock is a length of a tubular pipe, wherein the tubular pipe has a wall thickness, wherein the premium coupling machining blank has a maximum wall thickness, and wherein the wall thickness of the tubular pipe is less than the maximum wall thickness of the premium coupling machining blank.

50. The forging method as claimed in claim 49 wherein the premium coupling machining blank has a minimum wall thickness and wherein the wall thickness of the tubular pipe is greater than the minimum wall thickness of the premium coupling machining blank.

51. The forging method as claimed in claim 49 wherein the premium coupling machining blank has a length and wherein the length of the premium coupling machining blank is greater than the length of the tubular pipe.

52. The forging method as claimed in claim 49, further comprising controlling finning between the first press die and the second press die while producing the forged product.

53. The forging method as claimed in claim 52 wherein the first press die and the second press die define a variable press die gap between them as they extend within and withdraw from the holding cavity and wherein controlling finning is comprised of spanning the press die gap throughout a range of the press die gap.

54. The forging method as claimed in claim 53 wherein spanning the press die gap is comprised of providing a variable spanning device for spanning the press die gap throughout a range of the press die gap.

55. The forging method as claimed in claim 54 wherein the spanning device is comprised of an inner die telescopically received within a one of the first press die and the second press die such that the inner die is capable of reciprocable movement, relative to the one of the first press die and the second press die, between an extended position and a retracted position in order to span the press die gap throughout the range of the press die gap.

56. The forging method as claimed in claim 55 wherein spanning the press die gap is further comprised of biasing the inner die toward the extended position and moving the inner die toward the retracted position by overcoming the bias.

57. The forging method as claimed in claim 54 wherein the spanning device is comprised of a first inner die telescopically received within the first press die, wherein the first inner die is capable of reciprocable movement relative to the first press die between an extended position and a retracted position, wherein the spanning device is further comprised of a second inner die telescopically received within the second press die, and wherein the second inner die is capable of reciprocable movement relative to the second press die between an extended position and a retracted position.

58. The forging method as claimed in claim 57 wherein spanning the press die gap is further comprised of engaging the first inner die and the second inner die with each other in order to span the press die gap throughout the range of the press die gap.

59. The forging method as claimed in claim 58 wherein spanning the press die gap is further comprised of biasing each of the first inner die and the second inner die toward the extended position and wherein spanning the press die gap is further comprised of moving the first inner die and the second inner die toward the retracted position by overcoming the bias.

60. The forging method as claimed in claim 58 wherein spanning the press die gap is further comprised of actuating each of the first inner die and the second inner die toward the extended position.

61. The forging method as claimed in claim 60 wherein spanning the press die gap is further comprised of hydraulically actuating each of the first inner die and the second inner die toward the extended position.

62. A forging method for forging a forging stock into a forged product, the forging method comprising:

(a) providing a holding die assembly having a first end and a second end and defining a holding cavity extending between the first end and the second end;

(b) positioning the forging stock in the holding cavity;

(c) providing a press die apparatus comprising a first press die and a second press die opposed to the first press die, wherein the first press die and the second press die are selectively relatively movable toward each other within the holding cavity to a closed position of the press die apparatus and away from each other to an open position of the press die apparatus;

(d) relatively moving the first press die and the second press die to the closed position of the press die apparatus in order to forge the forging stock, thereby producing the forged product;

(e) controlling finning between the first press die and the second press die while producing the forged product;

(f) relatively moving the first press die and the second press die to the open position of the press die apparatus; and

(g) removing the forged product from the holding cavity.

63. The forging method as claimed in claim 62 wherein the first press die and the second press die define a variable press die gap between them as they relatively move toward and away from each other and wherein controlling finning is comprised of spanning the press die gap throughout a range of the press die gap.

64. The forging method as claimed in claim 63 wherein spanning the press die gap is comprised of providing a variable spanning device for spanning the press die gap throughout a range of the press die gap.

65. The forging method as claimed in claim 64 wherein the spanning device is comprised of an inner die telescopically received within a one of the first press die and the second press die such that the inner die is capable of reciprocable movement, relative to the one of the first press die and the second press die, between an extended position and a retracted position in order to span the press die gap throughout the range of the press die gap.

66. The forging method as claimed in claim 65 wherein spanning the press die gap is further comprised of biasing the inner die toward the extended position and moving the inner die toward the retracted position by overcoming the bias.

67. The forging method as claimed in claim 64 wherein the spanning device is comprised of a first inner die telescopically received within the first press die, wherein the first inner die is capable of reciprocable movement relative to the first press die between an extended position and a retracted position, wherein the spanning device is further comprised of a second inner die telescopically received within the second press die, and wherein the second inner die is capable of reciprocable movement relative to the second press die between an extended position and a retracted position.

68. The forging method as claimed in claim 67 wherein spanning the press die gap is further comprised of engaging the first inner die and the second inner die with each other in order to span the press die gap throughout the range of the press die gap.

69. The forging method as claimed in claim 68 wherein spanning the press die gap is further comprised of biasing each of the first inner die and the second inner die toward the extended position and wherein spanning the press die gap is further comprised of moving the first inner die and the second inner die toward the retracted position by overcoming the bias.

70. The forging method as claimed in claim 68 wherein spanning the press die gap is further comprised of actuating each of the first inner die and the second inner die toward the extended position.

71. The forging method as claimed in claim 70 wherein spanning the press die gap is further comprised of hydraulically actuating each of the first inner die and the second inner die toward the extended position.