LONG CARTRIDGE CASE

Abstract

A method of forming a closed end metal tube comprising cutting a blank from a solid round metal wire, backward extruding an axial hole in the blank to produce a hollow sidewall with a thickness, and reducing the sidewall thickness by using one or more Modified Hooker extrusions.

Claims

1. A method of forming a closed end metal tube comprising cutting a blank from a solid round metal wire, backward extruding an axial hole in the blank to produce a hollow sidewall with a thickness, and reducing the sidewall thickness by using a Modified Hooker extrusion.

2. A method as set forth in claim 1, wherein during the Modified Hooker extrusion, the outer diameter of the sidewall is confined.

3. A method as set forth in claim 1, wherein a succession of Modified Hooker extrusions are performed on the sidewall.

4. A method as set forth in claim 1, wherein the forming part is finish drawn to the final sidewall thickness of the desired part.

5. A method as set forth in claim 4, wherein the method is performed on a single forming machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 illustrates forming steps used in practice of the invention;

[0007] FIG. 2 shows the start of the Modified Hooker extrusion; and

[0008] FIG. 3 shows the completion of the Modified Hooker extrusion.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0009] The forming steps illustrated in FIG. 1 are typically done on a multi-station cold forming machine. A blank 10 is cut off from a solid round metal wire fed to the forming machine. At a first station the blank 10 is squared up, and at a second station the blank 10 is backward extruded with an inside diameter reduced from what was previously done, thereby reducing tool loads. The required forming load to produce a backward extruded hole decreases as the reduction in area decreases. Here the backward extrusion results in a hole that is minimal while the earlier process requires a hole that is maximal to form a mouth of the blank.

[0010] The backward extruded blank 10 as shown in FIG. 1, is subjected to a first Modified Hooker extrusion at the next station and a second Modified Hooker extrusion at the following station. FIG. 2 illustrates the start of a Modified Hooker extrusion, and FIG. 3 illustrates the completion of a Modified Hooker extrusion. It is seen from FIGS. 2 and 3 that only the sidewall of the blank 10 is extruded so that the reduction in area is relatively small. The estimated total forming load is reduced by 50% and the energy consumption is reduced by 40% compared to previously multiple backward extrusion processes. The part can be finish drawn to the final sidewall thickness of the desired part on the same forming machine as the previous forming steps are performed.

[0011] It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.