IMPROVED END CAP

Abstract

The invention relates to a method of improved ammunition production, particularly to a metal matrix composite(MMC) end cap, suitable for forming a cartridge case, said end cap comprising an admixture of a metal powder, a binder matrix material, wherein said admixture has been caused to solidify in the shape of said end cap.

Claims

1. A metal matrix composite(MMC) end cap, suitable for forming a cartridge case, said end cap comprising an admixture including a metal powder and a binder matrix material, wherein said admixture has been caused to solidify in the shape of said end cap.

2. The end cap of claim 1, wherein the metal powder is selected from aluminium composites, magnesium composites or copper composites.

3. The end cap according to claim 1, wherein the binder matrix material is selected from a further metal powder, polymers, ceramics.

4. The end cap according to claim 3, wherein the further metal powder has a lower density than the metal powder.

5. The end cap according to claim 1, wherein the admixture further comprises reinforcement particulates in the range of greater than 10%.

6. The end cap according to claim 5, wherein the reinforcement particulates are selected from ZrO.sub.2, TiC, TiN, AlN, graphite, clay, SiC, Al.sub.2O.sub.3, and B.sub.4C.

7. The end cap according to claim 1, wherein the admixture is consolidated, cured, or sintered by hot isostatic pressing.

8. An ammunition round, comprising: the end cap according to claim 1; a case, said case and end cap forming a cartridge case; primer; propellant; and a projectile located in said cartridge case arranged to form said round.

9. The round according to claim 8, wherein the case is a metal, metalloid or polymer case.

10. The round according to claim 9, wherein said case is mechanically joined, laser welded or bonded to the end cap.

11. The round according to claim 10, wherein said case is mechanically joined to the end cap by a rivet.

12. The round according to claim 10, wherein the case is a polymer case that is formed in-situ over the end cap, wherein said end cap further comprises an elongate protrusion to engage with said polymer case.

13. An ammunition round, comprising: an end cap comprising an admixture including a metal powder and a binder matrix material, said admixture being solidified in the shape of said end cap; and a case comprising a metal, a metalloid, or a metal alloy, the case and end cap forming a cartridge case.

14. The ammunition round according to claim 13, further comprising: a primer cap; and a projectile located in said cartridge case.

15. The ammunition round according to claim 13, wherein the case is mechanically joined, laser welded, or bonded to the end cap.

16. The ammunition round according to claim 15, wherein the mechanical join is a rivet.

17. An ammunition round, comprising: an end cap comprising an admixture including a metal powder and a binder matrix material, said admixture being solidified in the shape of said end cap; a case comprising a metal, a metalloid, or a metal alloy, the case and end cap forming a cartridge case; a primer cap; and a projectile located in said cartridge case; wherein the case is mechanically joined to the cellular structure end cap by a clamping flange.

18. The ammunition round according to claim 17, wherein the clamping flange is part of a deformable member that extends along a passage in the cellular structure end cap and through an orifice of the case, the clamping flange fixing the case and cellular structure end cap together.

19. The ammunition round according to claim 17, wherein the clamping flange is part of a rivet-like element, and the rivet-like element either: is integral with the end cap and extends from the end cap through an orifice of the case, the clamping flange fixing the case and end cap together; or is separate from both the end cap and the case, the clamping flange being one of a first clamping flange and a second clamping flange, the rivet-like element extending along a passage in the end cap and through an orifice of the case, the first and second clamping flanges fixing the case and end cap together.

20. The ammunition round according to claim 17, wherein the case is mechanically joined to the end cap by a mechanical rivet join that includes the clamping flange, the ammunition round including a sealant between the end cap and the case.

Description

[0054] FIG. 1 prior art brass cartridge case.

[0055] FIG. 2 shows a bonded arrangement of a polymer case and MMC MMC end cap

[0056] FIG. 3 shows an alternative bonded arrangement of a polymer case and MMC end cap unit.

[0057] FIGS. 4a and 4b show mechanical fastening of a metal case and MMC end cap unit

[0058] FIG. 5 shows a laser weld fastening of a metal case and MMC end cap unit.

[0059] FIG. 6 shows a metal matrix composite MMC end cap Turning to FIG. 1 there is a prior art, conventional cartridge casing 10.

[0060] The cartridge assembly 10 comprises a casing 12 and a projectile 14. The casing 12 has a hollow section 16, which will contain propellant for displacement of the projectile 14. The casing 12 further comprises a head 18 at the end opposite to the projectile 14 which comprises a chamber 20 for a percussion cap, and a flash tube 22 for communication of an ignition charge from the percussion cap to the inside of the casing 12 and thus the propellant. The walls of the chamber 16 are formed integrally with the head 18. Such a cartridge casing may typically be formed of brass. This material choice has many advantages, for example, it is relatively easy to form into the desired shape. However, brass has demerit in that it is also relatively dense, and hence the casing 12 forms a relatively large percentage of the mass of the whole cartridge

[0061] Referring to FIG. 2, there is provided a head unit 20, which comprises an enlarged head rim 25, on a MMC head unit 35. The MMC 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 MMC metal coupling protrusion 22 engages with the polymer case 31, at the polymeric coupling end 33, and the forms an abutting engagement 32.

[0062] The MMC 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 MMC forming process.

[0063] Referring to FIG. 3, there is provided a head unit 40, which comprises an enlarged head rim 45, on a MMC head unit 55. The MMC 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 MMC 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 MMC coupling protrusion 42.

[0064] 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.

[0065] 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.

[0066] Turning to FIG. 4a shows a light weight metal cartridge casing 130. The cartridge casing 30 is configured for use in a rifled barrel of a gun, firearm or other such weapon.

[0067] The cartridge casing 130 comprises a casing tube 132 having a first end 134 which forms a base of the casing tube 132. The walls of the casing tube 132 turn at a corner edge 135 to define the first end 134. The corner edge 135 may have a radiussed, or arcuate, cross-section.

[0068] The casing tube 132 abuts at least part of a MMC head cap 136 provided adjacent the first end 134. The MMC head cap 136 is configured to support and reinforce the base of the casing tube 132 to prevent it from swelling and rupturing during operation. In part it achieves this by providing reinforcement to the end wall of the casing tube 132 which abuts the head cap 136.

[0069] Additionally, the MMC head cap 136 is provided with a shoulder edge 137. The shoulder edge 137 may be formed integrally with the MMC head cap 136. The shoulder edge 137 is provided towards the outer edge of MMC head cap 136, and extends in a longitudinal direction away from the head cap 136. The shoulder edge 137 may have a radiussed, or arcuate, cross-section. The corner edge 135 and shoulder edge 137 may be complementary in shape.

[0070] The corner edge 135 and shoulder edge 137 are sized and configured such that when the first end 134 of the casing tube 132 is seated on the MMC head cap 136, the corner edge 135 of the casing tube 132 sits within the space, or region, defined by the shoulder edge 137 of the MMC head cap 136. That is to say, the corner edge 135 and shoulder edge 137 are sized and configured such that when the first end 134 of the casing tube 132 is seated on the MMC head cap 136, the shoulder edge 137 of the MMC head cap 136 surrounds, encircles and/or bounds the corner edge 135 of the casing tube 132. Put another way, when the first end 134 of the casing tube 132 is fitted and located on the MMC head cap 136, the shoulder edge 137 of the MMC head cap 136 is substantially in contact with the whole of the circumference of corner edge 135 of the casing tube 132, and the shoulder edge 137 is configured to support loads induced in it by expansion of the casing. Thus, in operation, the shoulder edge 137 of the MMC head cap 136 prevents the corner edge 135 of the casing tube 132 from moving radially outwards, for example beyond its original circumference or the circumference of the MMC head cap 136.

[0071] The casing tube 132 further comprises a second end 138, which is open and configured to receive a projectile 189 opposite to the first end 134. The second end 138 has a diameter which may be substantially the same as, or less than, the diameter of the first end 134. In the example shown the diameter of the second end 138 is substantially less than the diameter of the first end 134.

[0072] The walls of the casing 132 define a substantially cylindrical thin walled chamber 140. The walls of the casing tube 132 are configured to contain a pressure in the chamber of up to about 500 MPa.

[0073] The MMC head cap 136 defines a passage 146 which extends all of the way through the MMC head cap 136 which in use will be a flash tube. The flash tube extends into a chamber 147 which, in use, will house a percussion cap (sometimes referred to as a primer). Thus the MMC head cap 136 has a percussion side 148 which, in use, faces away from the casing tube 132. The orifice 144 in the first end 134 of the casing tube 132 and head cap passage 146, when assembled in alignment, define a flash passage 150 which extends between the head cap percussion side 148 and the inside of the casing tube 132.

[0074] The MMC head cap 136 and casing tube 132 are held together by a deformable member 160. The deformable member 160 extends from the passage 146 of the MMC head cap 136 through the orifice 144 in the first end 134 of the casing tube 132 and aligns the passage 146 with the orifice 144.

[0075] In the example of FIG. 4a the deformable member 160 is provided as at least one deformable end, lip or region 162, which is deformable between a first shape (for example an undeformed configuration or state) in which the deformable member 160 may extend from the MMC head cap 136 through the casing tube 132 during assembly, and a second shape (for example a deformed configuration or state) which fixes the casing tube 132 and the MMC head cap 136 together. The deformable member 160 thus provides a mechanical joint between the MMC head cap 136 and casing tube 132.

[0076] In the example of FIG. 4a the deformable member 160 is integrally formed with the MMC head cap 136. The deformable member 160 is deformable by swaging the region of the lip 162 which extends beyond the wall which defines the orifice 144 of the casing tube 132 such that the lip 162 becomes pressed against the wall of the casing tube 132 and draws the MMC head cap 136 toward the base of the casing tube 132 to thereby clamp the casing tube 132 and MMC head cap 136 together.

[0077] An alternative example of a cartridge casing 180 according to the present disclosure is shown in FIG. 4b. The example of FIG. 4b is similar in many ways to the cartridge case shown in, and as described with reference to, FIG. 4a. Features common to the examples of FIG. 4a and FIG. 4b are referred to using the same reference numerals.

[0078] In the FIG. 4b example the deformable member 160 is provided as a rivet like element 182 which is provided separately to the MMC head cap 136 and casing tube 132. The deformable member 182 is cylindrical, hollow and thin walled. The deformable member 182 (rivet) extends along the passage 146 in the MMC head cap 136 and through the orifice 144 in the first end of the casing tube 132. The deformable member 182 is provided with at least one deformable end, or lip, 162 which is deformable between a first shape (for example an undeformed configuration or state) in which the deformable member 182 may extend between the casing tube 132 and the MMC head cap 136 during assembly, and a second shape (for example a deformed configuration or state) which fixes the casing tube 132 and MMC head cap 136 together. For example, the deformable end 162 of the deformable member 182 may be swaged to bring the MMC head cap 136 and casing tube 132 into a fixed relationship relative to one another.

[0079] The deformable end 162 of the deformable member 182 may take the form of a region of material which is configured to extend beyond the orifice 144 and passage 146 into the percussion cap chamber 147, which may then be swaged to form a clamping flange. Alternatively the deformable end 162 may be configured to extend into the casing tube 132. In such examples the deformable member 182 may be provided with a shoulder 184 of greater diameter than the orifice 144 and passage 146, on the opposite end of the deformable member 182 to the deformable region 162, such that the deformable member 182 is trapped against one side of the orifice 144 and passage 146.

[0080] Alternatively, a deformable end 162 may be provided at both ends of the deformable member 182 such that both end regions of the deformable member 182, that is to say the region which extends into the percussion cap chamber 147 and the region the extends into the casing tube 132, may be deformed to clamp against the MMC head cap 136 and the casing tube 132 respectively.

[0081] Put another way, the deformable member 182 is deformable by swaging either the region of a lip 162 which extends beyond the wall which defines the orifice 144 of the casing tube 132 and/or by swaging the region of a lip 162 which extends beyond the flash tube 144 into the percussion cap chamber 147. Swaging causes the lip 162 to become pressed against the wall of the casing tube 132 and/or MMC head cap 136 to thereby draw the MMC head cap 136 toward the base of the casing tube 132 to thereby clamp the casing tube 32 and MMC head cap 136 together.

[0082] The casing tube 132 may be formed from a metal, metallic material or metal alloy comprising, for example, aluminium or a titanium. In one example the casing tube 32 may comprise ferritic alloys, for example stainless steel. The casing tube 32 may alternatively be formed from non metallic material and/or metal-plastic composite material. The deformable member 160, i.e. the rivet 160, may be made of the same or a different material to the tube casing, for example stainless steel, titanium, brass or coated mild steel.

[0083] Turning to FIG. 5, shows an example cartridge casing 230 according to the present disclosure. The cartridge casing 230 comprises a casing tube 232 having a first end 234 which is closed by a MMC head cap 236. The casing tube 232 is substantially cylindrical and has an internal diameter at the first end 234 which receives the MMC head cap 236. The casing tube 232 bounds at least part of the MMC head cap 236 entered into its first end 234. The MMC head cap 236 is configured to support and reinforce the base of the casing tube 232 to prevent it from swelling and rupturing during operation. As will be described in more detail later, the MMC head cap 236 is welded to the casing tube 232, thereby fixing the MMC head cap 236 and casing tube 232 relative to one another.

[0084] In the context of the present disclosure, welding is intended to cover joining processes that produce bonding of materials by heating, which may be done with or without pressure or filler material. For example, the term is intended to encompass brazing and soldering. It may also be taken to encompass a process in which the material of one or more articles being joined are brought into a molten state to facilitate bonding. It may include a process in which the base materials melt along with a filler material.

[0085] The casing tube 232 further comprises a second end 238, which is open and configured to receive a projectile 289 opposite to the first end 234. The second end 238 has a diameter which may be substantially the same as, or less than, the diameter of the first end 234. In the example shown the diameter of the second end 238 is substantially less than the diameter of the first end 234.

[0086] The walls of the casing 232 define a substantially cylindrical thin walled chamber 240. The tube casing 232 has a substantially constant diameter along a first region of its length between the first end 234 and the second end 238. However, the cylindrical thin walled chamber 240 may have a taper (for example <1?) along at least part or all of its length.

[0087] The MMC head cap 236 defines a passage 246 which extends all of the way through the MMC head cap 236 which in use will be a flash tube (or flash passage). The flash tube/passage 246 extends into a chamber 247 which, in use, will house a percussion cap (sometimes referred to as a primer). Thus the MMC head cap 236 has a percussion side 248 which, in use, faces away from the casing tube 232.

[0088] The MMC head cap 236 further comprises a charge side 249 which, in use, defines part of the internal surface of the cartridge casing 230. Thus the flash passage 246 extends between the percussion side 248 and the charge side 249.

[0089] The MMC head cap 236 has an external diameter at least part way along its outer periphery sized such that it fits within the first end 234 of the casing tube 232. The relative dimensions of the internal diameter at the first end 2234 of the casing tube 232 and the external diameter of corresponding region of the MMC head cap 236 may be such when the MMC head cap 236 is located in the casing tube 232 they form an interference fit with one another.

[0090] The casing tube 232 and MMC head cap 236 may comprise a welded join which bonds them together in a region where they form an interference fit with one another. For example, the join may be provided around the circumference of the casing tube 232 and MMC head cap 236 in a region where they interface with one another. Such a region is indicated with arrows A. The join may be a through weld or stake weld.

[0091] Alternatively the casing tube 132 and MMC head cap 236 may comprise a join which bonds them together in the interior of the casing tube 232, for example in a region around a circumferential edge of an interface between the casing tube 232 and the MMC head cap 236. Such a region is indicated with arrows B.

[0092] The weld may achieved by laser welding. Alternative weld joins may be provided which brought only material of the casing tube 232 into a molten state, or brought material of both the casing tube 232 and MMC head cap 236 into a molten state. The weld join may have been provided by any one of the welding processes as hereinbefore defined.

[0093] FIG. 6 provides a MMC end cap 300, comprises a rim 306, an ejector groove 311, formed as a recess in the side wall 312 and rim 306, for locating with an ejection mechanism (not shown) in a rapid fire gun. There end cap comprises a first cavity the cap chamber 307 for receiving a primer cap (not shown), and a second cavitya fire hole 308, which is through-hole through which the primer cap's energetic output travels to initiate the gun propellant located in the adjoining cartridge case. The rear face 101 typically comprises the manufactures makers mark, for identification purposes. The end cap is formed from an MMC 305, which comprises a metal 302, binder 303 and optionally reinforcement particles 304.

[0094] The MMC end cap 300 may be secured to the case (not shown), via an abutment to the upper surface 309. The abutment may be reinforced by mechanical, chemical or physical fastenings. The protrusion 310, may be a shoulder for engagement with a metal case, or the protrusion 310 may be caused to elongated to provide a greater surface area for use with a polymer case.