US3680381A

US3680381A - Method of and apparatus for forming parts with re-entrant surfaces

Info

Publication number: US3680381A
Application number: US92045A
Authority: US
Inventors: Pierre Portal
Original assignee: FORGES DE BOLOGNE SA
Current assignee: FORGES DE BOLOGNE SA; Sa Forges De Bologne
Priority date: 1969-12-19
Filing date: 1970-11-23
Publication date: 1972-08-01
Anticipated expiration: 1989-08-01
Also published as: DE2058176A1; SU489288A3; FR2071194A5; BE758732A; GB1319093A

Abstract

A turbine or compressor blade with projections adjacent each end having one or more arcuate re-entrant surfaces is initially forged and is finish formed, either hot or cold, in a mould which defines the aerodynamic portion of the blade. The projections are finish formed by punches and after retraction of the punches, the mould halves are separated by a pivotal movement about an axis which contains the center of curvature of the arcuate re-entrant surfaces thus enabling the formed blade to be removed.

Description

United States Patent Portal [45] Aug. 1, 1972 [54] METHOD OF AND APPARATUS FOR [56] References Cited FORMING PARTS WITH RE-ENTRANT UNTTED STATES PATENTS SURFACES 2,751,667 6/1956 Gruet en ..29/156.8 [721 lnvemo" Bdogne, France 1,910,943 5/1933 Wiberg et al. ..29/l56.8 [73] Assignee: S.A. Forges de Bologne, Bologne,

France v Primary Examiner-Lowell A. Larson Attorney-John Lezdey [22] Filed: Nov. 23, 1970 [57] ABSTRACT [21] Appl 92045 A turbine or compressor blade with projections adjacent each end having one or more arcuate re-entrant [30] Foreign Application Priority Data surfaces is initially forged and is finish formed, either hot or cold, in a mould which defines the aerodynamic Dec. 19, 1969 France ..6944249 portion of the blade The projections are finish formed by punches and after retraction of the punches, the [52] US. Cl. ..72/354, 72/357, 72/360 mould halves are separated by a pivotal movement [51] Int. Cl. ..B2lj 13/02 about an axis which contains the center of curvature [58] Field of Search .,72/354, 357, 360, 373, 374, of the arcuate re-entrant surfaces thus enabling the 72/376, 377; 29/l56.8 B; l8/DIG. 58

formed blade to be removed.

2 Claims, 3 Drawing Figures METHOD OF AND APPARATUS FOR FORMING PARTS WITH RE-ENTRANT SURFACES BACKGROUND OF THE INVENTION 1. Field of the Invention.

The present invention relates to a method and apparatus for the finish forming of forged parts having reentrant surfaces.

2. Description of the Prior Art.

There are used in the construction of stators or rotors of turbo-machines, blades having an aerodynamic profiled portion and which are connected to one or more crowns or shrouds forming the rim or the hub of the wheel.

Each blade comprises at least one lateral projection or other securing means by which it is secured respectively to the rim or to the hub of the rotor or stator, the projection comprising arcuate surfaces of which some are reentrant.

Previously proposed methods of forging between two matrices or two molds do not permit removal from the mold of parts having a re-entrant surface.

At the present time when forged parts are used, it is necessary to machine the parts with a machine tool in order to form re-entrant surfaces on the projections or other securing means.

This method is time-consuming and costly.

SUMMARY OF THE INVENTION According to the present invention there is provided a method of forming a forged part with at least one reentrant surface on a projection thereof comprising the steps of confining a forged blank of the part in a space defining the final dimensions of a portion of the forged part, applying pressure to the projection of the blank to form said re-entrant surface, releasing said pressure, and removing the formed forged part from the space.

Further according to the present invention there is provided a method of finish forming an elongate forged part having a main portion and a lateral projection adjacent each end thereof, each said lateral projection having at least one laterally extending surface of arcuate form, the center of radius of which surfaces lies on the longitudinal axis of the part, said method comprising the steps of confining a forged blank of the part in a space defining the final dimensions of the main portion of the part, said space being defined by mold parts movable towards and away from one another along an arcuate path the center of which coincides with the center of radius of the laterally extending arcuate surfaces, applying pressure endwise of the blank to form said projections with their arcuate surfaces, releasing said pressure, and moving the mold parts relatively to one another along said arcuate path whereby to release the elongate part in its final dimensions.

Still further according to the present invention there is provided apparatus for finish forming a forged part having at least one re-entrant surface on at least one lateral projection thereof said apparatus comprising two mold members, each having formed therein depressions corresponding to a portion of the finishforrned part, and at least one recess leading to that portion of the depression which defines the re-entrant surface, means pivotally connecting the mold members, a punch slidable in said recess to engage the projection and form the re-entrant surface, a fluid-operated actuator for operating the punch, and means for pivoting the mold parts about an axis containing the center of the arcuate surface whereby the finish formed part can be removed along a corresponding arcuate path.

The method in accordance with the invention, enables the production from a rough blank made in accordance with known forging methods, a part with final dimensions.

Moreover, the method in accordance with the invention enables, by avoiding machining the lateral projections, also obviates interrupting the flow lines in the grain of the metal at the juncture of the profile with the projections and thus to increase the fatigue stress limit of the vanes.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing, in which:

FIG. 1 is an elevation of a blank produced by forging and before forming in accordance with the present invention;

FIG. 2 is a similar view of the part after forming; and

FIG. 3 is a partially sectioned perspective view of apparatus for forming a part in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A blank is shown in FIG. 1 which comprises a blade 1 having an aerodynamic profiled main portion and two

lateral projections

2, 3, or other securing means disposed at the ends of the blade I. The

projections

2, 3, comprise, respectively, two optional locating

parts

4, 5 in order to facilitate centering of the blade as a whole.

As is shown in FIG. 1, the securing means 2, 3 produced by forging have

surfaces

6, 7, 8, 9 which are only of tapered form, i.e., are not re-entrant.

The method in accordance with the invention enables the production of a finished part as shown in FIG. 2, in which arcuate surfaces 10 of radius R and center 0 as well as circular faces 11 of radius r and center 0 are of re-entrant form.

The apparatus for carrying out the method is shown in FIG. 3 and includes two forming members l2, l3 defining a space 14 in which the blank 1, shown in FIG. 1, is located.

The space 14 has a shape that is complementary to that of the final part, is open at its two ends and extends into recessed portions l5, 16 in which

punches

17, 18 are displaceable under the action of pressure-fluid actuators, the pistons of which 19 and 20 are rigid with the said punches.

The forming member 12 is pivoted to the member 13 about the axis xx by means of pins 21 of which one only is shown in FIG. 3, the said axis xx, being coincident with the center 0 (FIG. 2) for facilitating the demolding operation.

The part I, when disposed in the space 14 is held between the two forming

members

12, 13 which are held together by locking means of any suitable form exerting a force acting in a direction as indicated by the arrow F, said punches l7, 18 being slidable as indicated by the arrows A and B, in the

portions

15, 16 of the space 14 under the action of

actuators

19 and 20. The

projections

2 and 3 take up the form defined by the bottom of the

portions

15, 16 of the space and the end faces of the

punches

17, 18.

The form of the projections thus produced corresponds to that shown in FIG. 2.

Before removal from the mold, the

punches

17, 18 are moved apart in directions opposite to the arrows A and B and the forming member 12 is pivoted about the axis xx, in order to free the part 1 from the member 13 likewise by an arcuate movement.

Although the method described relates particularly to blades of turbo machines, it is clear that it may be applied to the production of any parts necessitating removal from a mold by a rotational movement after forging.

What is claimed is:

1. A method of finish forming an elongate forged part having a main portion and a lateral projection adjacent each end thereof, each said lateral projection having at least one laterally extending surface of arcuate form, the center of radius of which surfaces lies on the longitudinal axis of the part, said method comprising the steps of confining a forged blank of the part in a space defining the final dimensions of the main portion of the part, said space being defined by mold parts mova ble towards and away from one another along an arcuate path the center of which coincides with the center of radius of the laterally extending arcuate surfaces,

applying pressure endwise of the blank to form said projections with their arcuate surfaces,

releasing said pressure, and

moving the mold parts relatively to one another along said arcuate path whereby to release the elongate part in its final dimensions.

2. Apparatus for finish forming a forged part having at least one re-entrant surface on at least one lateral projection thereof said apparatus comprising two mold members, each having formed therein depressions corresponding to a portion of the finish-formed part, and at least one recess leading to that portion of the depression which defines the re-entrant surface,

means pivotally connecting the mold members,

a punch slidable in said recess to engage the projection and form the re-entrant surface,

a fluid-operated actuator for operating the punch,

and

means for pivoting the mold parts about an axis containing the center of the arcuate surface whereby the finish formed part can be removed along a corresponding arcuate path.

Claims

1. A method of finish forming an elongate forged part having a main portion and a lateral projection aDjacent each end thereof, each said lateral projection having at least one laterally extending surface of arcuate form, the center of radius of which surfaces lies on the longitudinal axis of the part, said method comprising the steps of confining a forged blank of the part in a space defining the final dimensions of the main portion of the part, said space being defined by mold parts movable towards and away from one another along an arcuate path the center of which coincides with the center of radius of the laterally extending arcuate surfaces, applying pressure endwise of the blank to form said projections with their arcuate surfaces, releasing said pressure, and moving the mold parts relatively to one another along said arcuate path whereby to release the elongate part in its final dimensions.

2. Apparatus for finish forming a forged part having at least one re-entrant surface on at least one lateral projection thereof said apparatus comprising two mold members, each having formed therein depressions corresponding to a portion of the finish-formed part, and at least one recess leading to that portion of the depression which defines the re-entrant surface, means pivotally connecting the mold members, a punch slidable in said recess to engage the projection and form the re-entrant surface, a fluid-operated actuator for operating the punch, and means for pivoting the mold parts about an axis containing the center of the arcuate surface whereby the finish formed part can be removed along a corresponding arcuate path.