US3355795A - Manufacture of tubing and clad rods or wire - Google Patents

Description

K. B. CLARK 3,355,795

TUBING AND AD R DS 0 2 Sheets-Sheet 1 K. B. CLARK 3,355,195

MANUFACTURE OF TUBING AND CLAD RODS OR WIRE Dec. 5, 1967 2 Sheets-Sheet 2 Filed June 10, 1964 FIGS.

FIGS.

United States Patent ()fifice 3,355,795 Patented Dec. 5, 1967 3,355,795 MANUFACTURE OF TUBING AND CLAD RODS OR WIRE Kenneth B. Clark, Spragueville, R.I., assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed June 10, 1964, Ser. No. 374,023 2 Claims. (Cl. 29-481) ABSTRACT OF THE DISCLOSURE Tubing, clad rods, wires and the like are manufactured in a continuous operation from hard-metal strip material bent to form a cylinder and edge-bonded in the solid phase by rolling. This involves the formation of certain fins with good bonding in the fin regions but weaker bonding interiorly of the fins. Heretofore the fins have been eliminated by skiving or drawing of the cylinders which removed or damaged the best bonded edge portions and damaged the weaker interior bonds. According to the invention, prior to skiving or drawing, the cylinders are subjected to substantial sintering before rather than after such fin elimination, which strengthens the weak interior bonds so as to be proof against the damaging effects of the skiving which removes the fins. The bending, bonding, sintering and fin elimination occur in a single pass. By this means, which may be carried out in a rapid continuous process, the initially weak inner portions of the solid-phase bonds, as rolled, can be effectively improved by the sintering, rather than having such weak portions so damaged by premature skiving or drawing operation that the sintering would be incapable of adequately improving the bonds.

Among the several objects of the invention may be noted the provision of improved means for the manufacture of tubing and clad rods, wires and the like which are made from bonded sheets formed as cylinders or the like; the provision of means of the class described according to which bonded fins which are a concomitant of sheet-to-sheet bonds can be removed without substantially producing an inferior product; and the provision of means of the class described which may be easily car ried out at low cost. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the ingredients and combinations of ingredients, the proportions thereof, steps and sequencec of steps, and features of composition and manipulation which will be exemplified in the products and methods hereinafter described, and the scope of the application of which will be indicated in the following claims. I I

In the accompanying drawings, in which several of various possible embodiments of the invention are illustrated,

FIG. 1 is a diagrammatic view illustrating one form of the invention;

FIG. 2 is a view similar to FIG. 1, showing said form of the invention in finished condition;

FIG. 3 is a view similar to FIG. 1, showing a second form of the invention;

FIG. 4 is a view similar to FIG. 3, showing said second form in finished condition;

FIG. 5 is a view illustrating certain apparatus for making a clad rod or wire such as shown in FIGS. 1 and 2;

FIG. 6 is a view similar to FIG. 5, showing apparatus for making a tube such as shown in FIGS. 3 and 4;

FIG. 7 is a cross-sectional view illustrating certain skiving apparatus; and

FIG. 8 is a section taken on line 8-8 of the skiving apparatus of FIG. 7.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawmgs.

Hereinafter the terms clad rod and clad wire are to be taken as synonymous, their difference being one of size primarily. The term metal means any deformable or malleable metal, including alloys. The term solid-phase green bond as used herein means a bond made under conditions such as set forth in US. Patents 2,691,815 and 2,753,623, and in most cases preferably the latter.

My two copending United States patent applications, Ser. No. 63,678, filed Oct. 19, 1960, entitled Forming and Solid-Phase Bonding, and Ser. No. 93,513, filed Mar. 6, 1961, entitled Manufacture of Clad Rods, Tubing and Clad Tubing, disclose methods for manufacturing tubes, clad rods and clad wires by transversely bending strips of metal to form cylinders and solid-phase bonding the margins of the strips. Ser. Nos. 63,678 and 93,513 have eventuated as US. Patents Nos. 3,220,106 and 3,220,107, respectively. In the case of clad rod and wire, the sheets are bent around a core and, in addition to bonding the strip margins, the strips may also be bonded to the core material. In all cases, sheet-to-sheet connections are made by squeezing under sufficient pressure to obtain a deformation of properly cleaned surfaces sufiicient to bring about solid metal flow and a solid-phase green bond. The bonding operation results in fins which in most cases require removal. It is in connection with this removal that problems occur and which are solved by means of the present invention.

Referring now more particularly to FIG. 1, there is shown at numeral 1 a cylindrical metallic core clad by metallic sheets 2 and 3 of strip form, the latter having been solid-phase bonded to the core by passage through suitable grooved and beaded bending and squeezing rolls R (FIG. 5) and as set forth in said applications. Their grooves are shown at G and their beads at B. Solid-phase green bonding occurs between the core 1 and the sheets 2 and 3, and also at the pinch caused by the beads B of the rolls R. The pinch effect causes. green-bonded fin portions 4. In this case a green-bonded clad rod wire results.

If, as shown in FIG. 3, the core 1 is omitted and the sheets 2 and 3 are bent over a suitable mandrel M (FIG. 6) extending between the rolls R, then the flanges F of rolls again squeeze and form fin portions 4. In this case a green-bonded tube will result. Like letters and numerals designate like parts in FIGS. 5 and 6 and in FIGS. 1 and 3, only the core 1 of FIG 1 being missing in FIG. 3. In each of FIGS. 2 and 4 the bent strips 2 and 4 form a metal cylinder which is empty in FIG. 4 but infilled by the core 1 in FIG. 2.

In general, it is desirable that the fin portions 4 be removed, as by skiving, drawing or the like. For example, skiving is accomplished as shown in FIGS. 7 and 8. The skiving apparatus may consist of a pair of V-shaped guide wheels W, flanked by the skiving blades S. It has been the practice heretofore to skive off the fin portions 4 immediately after the solid-phase green-bonding operation, for example, simply by feeding the solid-phase, green-bonded material from the squeezing rolls R to the skiving apparatus W, S. This process has been found to be satisfactory in cases in which the sheets 2 and 3 were composed of soft material, for example, gold. These bond readily across the entire interface within the fins 4.

I have found, however, that difiiculties occur when the sheet material is comparatively hard for forming the cladding (FIG. 1) or the tubing (FIG. 3), such as, for example, nickel, stainless steel or Monel, and in cases in which solid-phase green-bonding temperatures are low. These difficulties arise in both the clad rod and tube forms of FIGS. 1 and 3, and more likely in the latter case. The difficulties reside in the following (referring to FIGS.

1 and 3) In the case of hard materials, the weakest solid-phase green-bonding occurs in the region of the short heavy solid black lines 5, which is to say, at the inside of the fin junctions formed by the sheets 2 and 3. Outside of these lines, there is generally sufficient deformation accomplished during squeezing to bring about a comparatively strong green bond. In the case of soft materials for the sheets 2 and 3, the comparatively poorly bonded black-line portion is minimal or nonexistent. The harder the material of which sheets 2 and 3 are composed, the greater the extent of the portion indicated by the solid line 5.

Past practice has been to remove all or a substantial portion of the fins 4- by skiving, This removes the portion most likely to be better green-bonded. The removal of the fins at this stage may also damage the comparatively weak green bond which exists in the region 5. This damage sometimes is so severe that subsequent operations designed to improve the strength of the green bond are ineffective to improve its strength at all.

It will be understood that in general solid-phase green bonds are subsequently sintered to increase their strength to useful values in finished products. Such sintering has heretofore been carried out after the skiving operation above-mentioned.

I solve the above-mentioned difficulties by performing the sintering step at a time occurring between the roll squeezing step (FIGS. 5 or 6) and the skiving step (FIGS. 7 and 8). This has the effect of substantially increasing the bond strength in region 5. A strong bond is thereby obtained before fin removal throughout substantially the entire distance, or at least a very large portion of it, extending from the apex of each fin 4 inwardly to the inner cylindrical surface of the tube formed by the sheets 2 and. 3. This is true in both the cases shown in. FIGS. 1, 2 and FIGS. 3, 4.

An additional feature of the invention is that the intermediate sintering step shall be carried out at higher sintering temperatures than are generally employed for the purpose. The higher sintering temperatures permit very rapid difiusion across the zone line 5, with rapid growth of the weak green bond into a strong bond across the interface between the sheet margins so that fin removal may be accomplished soon thereafter. Heretofore, in the case of nickel, Monel mild steel, some stainless steels and the like employed for the sheet such as 2 and 3, a normal sintering temperature would have been in the range of 1100 F.-l400 F. According to the present invention, a high sintering temperature of 1500 F.-280() F. would be employed. It will be noted that in no event may the upper temperature exceed the lowest melting point of the metals employed as cladding or core materials. At such sintering temperatures, 90% of the full sintered bond strength may be obtained within a few seconds.

It will be observed in FIGS. 2 and 4 that skiving has been accomplished so as to leave substantially no exterior evidence of a fin or the like. A slight curvature of the skiving blades may be desirable for this purpose. It is to be understood that fins may also be removed or obliterated by a drawing operation, rather than or in addition to skiving, if desired. The terms removing or obliterating as applied to elimination of the fins 4 are to be taken as equivalents. The finished products (FIGS. 2 and 4) are of improved final strength, giving no substantial evidence of any discontinuity at the junctions between the bonded marginal interfaces of the strips 2 and 3 and presenting little or no evidence of any exterior protrusion where the fins have been removed or obliterated. The short lines transverse to the cross hatching in FIGS. 2 and 4 show where the improved bond lines are located but in practice they are hardly detectable microscopically, being quite free from inclusions, voids, etc., and therefore strong.

While the core 1 has been illustrated as being solid, it will be understood that it may itself consist of a tube, so that instead of obtaining a clad rod as illustrated in FIG. 2., a clad tube would be obtained.

It will be understood that the provision of the hightemperature sintering between the steps of solid-phase green bonding by rolls on the one hand, and the elimination of the fin portions by skiving or drawing on the other had, have the advantage that all operations can in a single pass be rapidly performed by a continuous rapid movement of the strip and core materials successively through the bonding rolls, then through a suitable furnace or other heating means, forming a high-temperature sintering, and finally moving the sintered material through skiving apparatus or drawing dies, without pause between operations.

It will be seen that one feature of the invention is the timing of the sintering step after the squeezing step and before the skiving step; and another preferable subsidiary feature is the employment of an unusually high sintering temperature. It is to be understood, however, that lower sintering temperatures may be employed but that they require longer sintering times.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above prodnets and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. The method of forming a well-bonded hard-metal cylinder without fins comprising transversely bendingby rolling at least one clean hard-metal strip to bring to gether margins thereof. and by said rolling effecting a squeezing together of said margins to green-bond the margins in the solid phase to form the cylinder with at least one fin wherein the best bondingis in the fin and a weaker bond occurs interiorly of the region of the fin, subjecting the finned green-bonded cylinder to heating at a sintering temperature to improve the interior weaker bond in the solid phase, and thereafter mechanically eliminating the fin. from the cylinder.

2. The continuous single-pass method of forming a well-bonded hard-metal cylinder without fins comprising continuously moving and transversely bending by rolling at least one clean hard-metal strip to bring together margins thereof and' by said rolling effecting squeezing together of said margins to green-bond the margins in the solid phase to form the cylinder with at least one fin wherein the best bonding is in the fin region and a weaker bond occurs interiorly of the region of the fin, continuously passing the finned green-bonded cylinder through a heated space at a sintering temperature of 1500 F. or more for a few seconds to improve the interior weaker bond in the solid phase, and thereafter continuously passing the sintered cylinder through mechanical means for eliminating the fin from the moving cylinder.

(References on following page) 6 References Cited 3,220,106 11/1965 Clark 29--474.1 X UNITED STATES PATENTS 3,220,107 11/ 1965 Clark 29497.5 X

5/1869 Vanstone 29-481 FOREIGN PATENTS Mannesmann 5 Great Britain. 2/ 1903 Mannesmann 2,9 1 573 JOHN CAMPBELL, Primary Examiner. 7/ 1956 Boessenkool et a1. 29-497.5

L. I. WESTFALL, Examiner.

Claims (1)

1. THE METHOD OF FORMING A WELL-BONDED HARD-METAL CYLINDRICAL WITHOUT FINS COMPRISING TRANSVERSELY BENDING BY ROLLING AT LEAST ONE CLEAN HARD-METAL STRIP TO BRING TOGETHER MARGINS THEREOF AND BY SAID ROLLING EFFECTING A SQUEEZING TOGETHER OF SAID MARGINS TO GREEN-BOND THE MARGINS IN THE SOLID PHASE TO FORM THE CYLINDER WITH AT LEAST ONE FIN WHEREIN THE BEST BONDING IS IN THE FIN AND A WEAKER BOND OCCURS INTERIORLY OF THE REGION OF THE FIN, SUBJECTING THE FINNED GREEN-BONDED CYLINDER TO HEATING AT A SINTERING TEMPERATURE TO IMPROVE THE INTERIOR WEAKER BOND IN THE SOLID PHASE, AND THEREAFTER THE INTERIOR WEAKER BOND IN THE FIN FROM THE CYLINDER.

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