# US 4,392,397 A · Method of producing a drawing die

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- Number: US 4,392,397 A
- Document ID: US4392397A
- Status: Granted
- Kind: A
- Application number: 06/161,197
- Filed: 1980-06-19
- Granted: 1983-07-12
- Earliest claimed: 1979-06-25
- Assignees: U.S. Philips Corporation
- Inventors: Adrianus R. C. Engelfriet; Adriaan J. G. Op Het Veld; Theodorus J. P. Van Vucht
- Web page: https://patentgrep.com/patent/US4392397A

## CPC

- B21C 3/025: {comprising diamond parts}
- B21C 3/18: Making tools by operations not covered by a single other subclass; Repairing
- B21C: MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL

## Abstract

The disclosure relates to the manufacture of wire-drawing dies. The disclosure provides a method for securing a core in a metal housing. The method begins with the clamping of an annulus, consisting of a hardenable metal alloy, around a cylindrical core consisting of a material such as polycrystalline diamond or boron nitride. The core is clamped so as to produce a permanent, radially compressive stress therein. The core-annulus combination is secured in a metal housing of a conventional shape.

## Claims

### Claim 1

A method of producing a wire-drawing die comprising the steps of:
providing a metal annulus having a bore; and
clamping a core directly in the bore of the annulus, said core consisting of a hard, wear-resistant material; characterized in that:
the annulus consists of a metal alloy which can be strengthened by a heat treatment; and
the method further comprises the step of increasing the ulitmate strength of the annulus by a heat treatment, while clamping the core therein.

### Claim 2 (depends on 1)

A method of producing a wire-drawing die as claimed in claim 1, characterized in that the core consists of polycrystalline diamond, polycrystalline cubic boron nitride, or mixtures thereof.

### Claim 3 (depends on 2)

A method of producing a wire-drawing die as claimed in claim 2, characterized in that the annulus consists of a precipitation hardenable copper alloy.

### Claim 4 (depends on 3)

A method of producing a wire-drawing die as claimed in claim 3, characterized in that the method further comprises the steps of:
securing the annulus in a metal housing; and
cutting a drawing passage through the core.