US3777362A

US3777362A - Method of manufacturing rods or wire of compound material

Info

Publication number: US3777362A
Application number: US00226759A
Authority: US
Inventors: J Nilsson; B Brinkeborn
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1971-03-04
Filing date: 1972-02-16
Publication date: 1973-12-11
Anticipated expiration: 1990-12-11
Also published as: DE2209728A1; GB1372652A; SE364884B; FR2128586A1; CA947700A; FR2128586B1; NL7202721A

Abstract

In manufacturing a rod or wire of compound material from a core of aluminum or aluminum alloy and a casing of copper or copper alloy by hydrostatic extrusion, a billet is used in which the core has a smaller external diameter than the internal diameter of the casing, so as to provide clearance therebetween sufficient that at least most damage to the casing during soft-annealing and handling will not be of sufficient extent to prevent the insertion of the core into a casing. An internal space is provided at the rear of the billet to collect the air present in the gap between the core and the casing as it is displaced when the core and casing are pressed into contact with each other.

Description

United States Patent Nilsson et a1.

[ 1 Dec. 11, 1973 METHOD OF MANUFACTURING RODS OR WIRE OF COMPOUND MATERIAL Inventors: Jan Nilsson, Robertsfors; Bertram Brinkeborn, Vasteras, both of Sweden Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden Filed: Feb. 16, 1972 Appl. No.: 226,759

Assignee:

Foreign Application Priority Data Mar. 4, I971 Sweden ..2756 /71 US. Cl 29/474.3, 29/479, 72/60 Int. Cl B2ld 39/04 Field of Search 72/60; 29/4733,

References Cited UNITED STATES PATENTS 3,698,067 10/1972 Feiss ..29/474.3X

Primary Examiner-J. Spencer Overholser Assistant Examiner-Richard Bernard Lazarus Attorneylennings Bailey, Jr.

[57] I ABSTRACT In manufacturing a rod or wire of compound material from a core of aluminum or aluminum alloy and a casing of copper or copper alloy by hydrostatic extrusion, a billet is used in which the core has a smaller external diameter than the internal diameter of the casing, so as to provide clearance therebetween sufficient that at least most damage to the casing during soft-annealing and handling will not be of sufficient extent to prevent the insertion of the core into a casing. An internal space is provided at the rear of the billet to collect the air present in the gap between the core and the casing as it is displaced when the core and easing are pressed into contact with each other.

8 Claims, 2 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing rods or wire of compound material having a core of aluminum or an aluminum alloy and a casing of copper or a copper alloy surrounding the core, by means of hydrostatic extrusion. At the start of themtrusion a compound billet is used consisting of a core of aluminum and asurrounding casing of a copper tube which are inserted in a pressure chamber containing a pressure medium. Under the influence of a high allsided hydrostatic pressure, the billet is forced out through an opening in a die and thus shaped to a product with the desired cross-section. During this process the core and casing at the rear end of the billet are tightly sealed, for example with a sealing ring or a lid of elastomeric material which prevents pressure medium from penetrating between the core and the surrounding tube.

2. The Prior Art The prior applications of Burstrom, Ser. No. 32,195, filed Apr. 27, 1970 now U. S. Pat. No. 3,654,687 and Nilsson, Ser. No. 758,308, filed Sept. 9, 1968 now U. S. Pat. No. 3,620,059 describe hydrostatic extrusion of compound products having a core of one material and a casing of another material.

It has been found that there are practical difficulties in joining a core and a casing if the clearance between them is small. During soft-annealing and handling of the tube for the casing it may curve, become ovalor be subjected to knocks resulting in dents. It may then be difficult or indeed impossible to insert the core in the casing.

SUMMARY OF TI-IE INVENTION The difficulties of insertion can be eliminated by making the clearance between the'core and the casing so large that normal'alterations in shape during annealing and handling of the copper tubing are of no importance; The considerable volume of air which is enclosed between the core and the casing'if there is much clearance may cause difficulties during the extrusion. Air bubbles enclosed between the core and the casing may jeopardize the adhesion and the casing may be loosened from the core in the finished product. According to the invention, the risks of the faults described above are eliminated by shaping the billet so that the quantity of air enclosed is with all certainty collected at the rear end of the billet which remains after the extrusion is complete. This can be achieved by arranging a space to collect the air at the rear end of the billet, the. surrounding walls have such strength that material in the copper casing or aluminum core is only pressed into this after the casing, under influence of the pressure in the surrounding pressure medium, has been pressed into contact with the core to such an extent that the gap between casing and core is disappeared.

Suitably an annular air-collecting space is arranged between the core and the casing at the rear part of the billet. If a pressure plate of steel, for example, is used, the annular space can be effected by bevelling the plate or a space can be arranged in the pressure plate and it may be shaped with grooves or channels through which air. can flow into the space.

It may be desirable to provide the core or copper tube with an axial groove through which air can flow back to the air-collecting space if the tube should be first pressed into contact with the core at the rear end of the billet upon a pressure increase in the pressure chamber. The invention makes it possible to have considerable clearance between the core and the casing without any risk that the enclosed air volume will cause any disturbance during the compression or that air pockets will exist in the finished product.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is further described with reference to the accompanying drawings. FIG. 1 shows schematically a section through a pressure chamber with a billet inserted and FIG. 2 shows on a larger scale the rear end of a billet with an alternative design of an air-collecting space.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, 1 designates a press stand and 2 a pressure-generating piston which is arranged in an hydraulic pressure device, not otherwise shown, in which there is a cylinder to operate the piston 2. The pressure chamber comprises a high pressure cylinder 3 which is constructed of a steel cylinder 4, a strip sheath 5 of rectangular tape of high strength wound on under prestress, and end pieces 6. Between the end closures6 and a spacing sleeve 7 in the cylinder are two seals 8 and 9 sealing between the cylinder 4 and the extrusion die 10 and piston 2, respectively. In the pressure chamber is a billet 11 consisting of a core 12 of aluminum or an allumiunm alloy and a surrounding casing 13 of copper or a copper alloy. Between the core 12 and the casing 13 there is considerable clearance so that an annular gap 14 is formed. The radial clearance for a core having a diameter of mm may be 5 mm or more. The clearance is usually between I and 5 mm. A steel plate 15 is inserted at the rear end of the billet. A lidshaped seal of elastomeric material surrounds the rear end of the billet and covers the joint between the plate 15 and the casing 13 and thus prevents the surrounding pressure medium 17 from penetrating into the gap 14. The plate 15 has a section "18 which projects into the tube 13. The projection 18 has a triangular bevelling 19.

In the embodiment shown in FIG. 1, the tube 13 is supported by the projection 18. The tube 13 thus acquires a certain support so that it will be pressed against the billet 12 before the tube material is pressed into the triangular air-collecting space 20 formed by the tube 13, the triangular bevelling l9 and the end surface of the core 12. To ensure that the air will collect in the space 20 even if the tube 13 should be pressed against the core 12 at the rear of the billet before being pressed against the front part of the billet, the core may be provided with at least one axial groove 21 through which air can flow from the front end of the billet to the aircollecting space.

FIG. 2 shows an embodiment of the billet in which the steel plate 15 is provided with a bowl-shaped aircollecting space 22 and radial grooves 23 through which the space 22 communicates with the triangular, annular space 20. The bevelling 19 may be provided with slots 24 through which air can flow to the slots 23 when the copper casing is forced into the space 20.

We claim:

1. Method of manufacturing rods or wire of compound material having a core consisting essentially of aluminum and a casing consisting essentially of copper surrounding the core, by means of hydrostatic extrusion of a billet formed from a core and a casing wherein the casing is sealed at the rear end of the billet and surrounds the core, which comprises inserting said billet in a pressure chamber and forcing the billet under the influence of a hydrostatic pressure through a die with an opening shaped to the desired cross-section, in which the billet is formed from a core having a smaller external diameter than the internal diameter of the easing, thereby providing a clearance therebetween which exceeds deformations normally occurring during annealing of the casing in which an internal space is provided at the rear of the billet to collect in the gap between the core and the casing air which is displaced when the core and the casing are pressed into adhering contact with each other.

2. Method according to claim 1, in which the normal radial clearance between the core and the casing exceeds 1 mm for a core diameter of mm.

3. Method according to claim 2, in which the nominal radial clearance is between 1 and 5 mm.

4. Method according to claim 1, in which the billet has a steel plate at the rear end of the billet, the space for collecting the air being in the vicinity of the steel plate.

5. Method according to claim 4, in which the steel plate has a part projecting into the casing, said part being bevelled so that an annular space is formed between the casing and the plate at the rear end surface of the core.

6. Method according to claim 5, in which the side of the plate facing the end surface of the core is provided with a hollow therein.

7. Method according to claim 6, in which one of the end surfaces of the plate or the core is provided with radial grooves between the hollow and the periphery.

8. Method accordinc to claim 1, in which the core or casing is provided with at least one axial air-conducting groove therein.

Claims

2. Method according to claim 1, in which the normal radial clearance between the core and the casing exceeds 1 mm for a core diameter of 100 - 150 mm.
3. Method according to claim 2, in which the nominal radial clearance is between 1 and 5 mm.
4. Method according to claim 1, in which the billet has a steel plate at the rear end of the billet, the space for collecting the air being in the vicinity of the steel plate.
5. Method according to claim 4, in which the steel plate has a part projecting into the casing, said part being bevelled so that an annular space is formed between the casing and the plate at the rear end surface of the core.
6. Method according to claim 5, in which the side of the plate facing the end surface of the core is provided with a hollow therein.
7. Method according to claim 6, in which one of the end surfaces of the plate or the core is provided with radial grooves between the hollow and the periphery.
8. Method accordinc to claim 1, in which the core or casing is provided with at least one axial air-conducting groove therein.