Pressed head

Abstract

The invention relates to a method of improved ammunition production, more specifically to an improved pressed metal head component suitable for a polymer tube cartridge The invention relates to a method of drawing and forming a metal head unit for use with a polymer case to form a polymer cartridge for use in a rifled barrel, comprising the steps of i) providing a metal cup drawing it through one or more dies to provide a case tube, wherein the case tube has a closed head end with a first outer diameter and an elongate open end, ii) trimming the elongate open end to form a metal coupling protrusion, said metal coupling protrusion with a second outer diameter, wherein the first diameter and second diameter are the same, iii) forming, a primer cavity into the closed head end, iv) forming internal and external features in the closed head end, v) forming by a heading process, an enlarged head rim on the closed head end, such that said enlarged head rim has a third diameter which is larger than the second diameter of the open end.

Claims

1. A method of drawing and forming a metal head unit for use with a polymer case to form a polymer cartridge for use in a rifled barrel, the method comprising: drawing a metal cup through one or more dies to provide a case tube, wherein the case tube has an elongate open end and a closed head end with a first outer diameter; trimming the elongate open end to form a metal coupling protrusion, said metal coupling protrusion with a second outer diameter, wherein the first outer diameter and the second outer diameter are substantially the same; forming a primer cavity into the closed head end; forming internal and external features in the closed head end; and forming, by a heading process, an enlarged head rim on the closed head end, such that said enlarged head rim has a third outer diameter which is larger than the second outer diameter of the open end.

2. The method according to claim 1, further comprising: forming a head stamp on the enlarged head rim, and piercing a through fire hole, and forming an ejector groove under the enlarged head rim.

3. The method according to claim 1, wherein the polymer case is located inside, outside, both inside and outside, or at least in part over the second outer diameter of the metal coupling protrusion.

4. The method according to claim 3, wherein an outer diameter of the polymer case and the third outer diameter of the enlarged head rim are substantially the same.

5. The method according to claim 2, wherein the enlarged head rim is formed by a heading process which simultaneously applies the head stamp.

6. The method according to claim 1, wherein the third outer diameter of the enlarged head rim is in the range of from 105% to 115% of the second outer diameter.

7. The method according to claim 2, wherein there is a further circumferential groove below the ejector groove, to accommodate a retaining portion of the polymer case.

8. The method according to claim 1, wherein said polymer case comprises a polymeric coupling end, and an open end for receiving a projectile or a closed end for forming a blank.

9. The method according to claim 8, wherein the polymeric coupling end engages with the metal coupling protrusion.

10. The method according to claim 8, wherein the polymeric coupling end is a female coupling portion with at least two polymeric skirt portions which engage with the metal coupling protrusion.

11. The method according to claim 10, wherein one of the at least two polymeric skirt portions is an outer polymeric skirt portion, which comprises a retaining portion of the polymer case, which engages with a circumferential groove of the metal head unit.

12. The method according to claim 10, wherein one of the at least two polymeric skirt portions is an inner polymeric skirt portion, which comprises a further retaining portion, which engages with a flash hole of the metal head unit.

13. The method according to claim 1, wherein the polymer case is fixed to the metal coupling protrusion.

14. The method according to claim 1, wherein the polymer case is formed from thermoset, thermoplastic, block polymers, co-polymers, elastomers, fluoroelastomers, fibre reinforced polymer composites, or combinations thereof.

Description

(1) Exemplary embodiments of the device in accordance with the invention will now be described with reference to the accompanying drawings in which:—

(2) FIGS. 1a and b show a metal head unit

(3) FIG. 2 shows a bonded arrangement of a polymer case and metal head unit

(4) FIG. 3 shows an alternative bonded arrangement of a polymer case and metal head unit.

(5) FIG. 4 shows a polymer cased ammunition round.

(6) FIGS. 5a and 5b show the formation of the enlarged head rim

(7) FIG. 6 shows an improved metal-composite bond arrangement

(8) FIG. 7 shows a metal cup and subsequent drawn tubes.

(9) Referring to FIGS. 1a and 1b, there is provided a metal head 1, which comprises an enlarged head rim 3, on a head unit 11. The head unit 11, comprises an ejector groove 10, and at least one further circumferential groove 6, to accommodate a portion of the polymer cartridge tube (not shown). The metal coupling protrusion 2, forms a coupling surface with the polymer cartridge tube (not shown).

(10) The head unit 11, comprises a primer cavity 4, and a flash hole 7, to allow the output from the primer (removed for clarity) to transfer through to propellant in the final cartridge. The internal features such as the internal shoulder 8 and flash hole aperture 9, are produced during the forming process.

(11) Referring to FIG. 2, there is provided a metal head 20, which comprises an enlarged head rim 25, on a head unit 35. The head unit 35, comprises an at least one further circumferential groove 26, which accommodates a retaining portion of the polymer case 34. The ejector groove 30 is in part formed by the enlarged head rim 25, and the retaining portion of the polymer case 34. The metal coupling protrusion 22 engages with the polymer case 31, at the polymeric coupling end 33, and the forms an abutting engagement 32.

(12) The head unit 35, comprises a primer cavity 24, and a flash hole 27, to allow the output from the primer (removed for clarity) to transfer through to propellant in the final cartridge. The internal features such as the internal shoulder 28 and flash hole aperture 29, are produced during the forming process.

(13) Referring to FIG. 3, there is provided a metal head 40, which comprises an enlarged head rim 45, on a head unit 55. The head unit 55, comprises an at least one further circumferential groove 46, which accommodates a retaining portion of the polymer case 54. The ejector groove 50 is in part formed by the enlarged head rim 45, and the retaining portion of the polymer case 54. The metal coupling protrusion 42 engages with the polymer case 51. The female polymeric coupling end 53, comprising the two skirt portions 52a and 52b envelope the metal coupling protrusion 42.

(14) The head unit 55, comprises a primer cavity 44, and a flash hole 47. In this arrangement the flash hole 47 is formed by the inner polymeric skirt portion 52a, which comprises a further retaining portion 59, which engages with the flash hole aperture 49. The further retaining portion 59 forms a narrower flash hole aperture 47. The flash hole 47 allows the output from the primer (removed for clarity) to transfer through to propellant in the final cartridge. The inner skirt portion 52a extends 58 and attaches to the internal shoulder 48 along its length.

(15) The outer polymeric skirt portion 52b extends down the outside the metal coupling protrusion 42. The outer polymeric skirt 52b and enlarged head rim 45 have substantially the same diameter.

(16) Turning to FIG. 4, there is provided a complete round 61, with a metal head unit 60, a polymer cartridge case 64, a cavity 65 for accepting propellant (propellant not shown), and a projectile 62, which located in the mouth 68 of the cartridge case. The upper end 63 of the cartridge case towards the shoulder 67, and neck portion 66, may be formed from the same or different polymer compositions.

(17) Turning to FIG. 5a, there is shown a head unit 70, with internal features provided, and a cavity 74a suitable for receiving the primer. The walls 72 of the head unit have a first diameter which is substantially that of the initial metal cup. The enlarged head rim is formed by the use of a heading tool 79, which impinges on the closed metal end 75a, forming an enlarged head rim 75b (FIG. 5b), and also forming a final sized primer cavity 74b. The head stamp 73, may be formed at the same time as the enlarged head rim 75b is formed.

(18) Turning to FIG. 6, there is provided a head unit 80, wherein the metal coupling protrusion 82, has a series of projection 85, which could be minor surface keying, or notches, or adhesive, onto which a fibre ply 83, or fibre windings 84 is located, such that when the polymer case is formed thereon the metal coupling protrusion 82 projections 85, and fibre ply form a metal composite bond.

(19) Turning to FIG. 7, there is shown a metal cup 90, which is well known and is a well-defined starting material for preparing brass ammunition. The metal cup 90 is placed on a transfer press, and drawn through a series of dies. The first draw 91, shows how the cup starts to elongate, and during subsequent drawing operations the case tube 92 is produced. The production of the case tube is known to those proficient in the art. Once the case tube 92 has been produced it is transferred to a forming press, where the metal head unit as defined herein in the earlier figures is formed to provide the enlarged head rim (shown in FIG. 1.).