Method of making a polymer ammunition cartridge having a metal injection molded primer insert

Patent metadata

Field	Value
Publication number	US-2016003595-A1
Application number	US-201514748554-A
Country	US
Kind code	A1
Filing date	Jun 24, 2015
Priority date	Nov 10, 2010
Publication date	Jan 7, 2016
Grant date	—

Abstract

The present invention provides a method of making a polymer ammunition cartridge having a metal injection molded primer insert.

First claim

What is claimed is:

1 . A method of making a polymer ammunition cartridge having a metal injection molded primer insert comprising by the steps of:
forming a substantially cylindrical metal primer insert by metal injection molding from a primer insert injection mold, wherein the substantially cylindrical metal primer insert comprises a top surface opposite a bottom surface and a substantially cylindrical coupling element that extends from the bottom surface, a primer recess in the top surface that extends toward the bottom surface, a primer flash aperture positioned in the primer recess to extend through the bottom surface, and a flange that extends circumferentially about an outer edge of the top surface; providing a first polymer composition for molding a polymer ammunition cartridge; molding from the first polymer composition a substantially cylindrical polymeric middle body having the substantially cylindrical metal primer insert at a first end and a substantially cylindrical polymeric coupling region at a second end, wherein the first polymer composition extends over an outer surface of the substantially cylindrical metal primer insert to the flange and extends over an interior surface of the substantially cylindrical coupling region to the primer flash hole aperture, wherein the first polymer composition extends from the substantially cylindrical polymeric coupling region to the primer flash hole aperture; forming a substantially cylindrical polymeric bullet-end component from a second polymer composition comprising a bullet aperture opposite a polymeric bullet-end coupling that mates to the substantially cylindrical coupling region; and coupling the substantially cylindrical coupling region to the polymeric bullet-end coupling to form a propellant chamber that extends from the primer flash hole aperture to the bullet aperture.

2 . The method of claim 1 , further comprising a primer flash aperture groove positioned in the primer recess around the primer flash aperture and the first polymer composition extends into the primer flash aperture to form a flash hole.

3 . The method of claim 1 , wherein the first polymer composition is the same as the second polymer composition.

4 . The method of claim 1 , wherein the first polymer composition is a ductile polymer.

5 . The method of claim 1 , wherein the first polymer composition, the second polymer composition or both comprise a nylon polymer.

6 . The method of claim 1 , wherein the first polymer composition, the second polymer composition or both comprise a fiber-reinforced polymeric composite.

7 . The method of claim 1 , wherein the first polymer composition, the second polymer composition or both comprise between about 10 and about 70 wt % glass fiber fillers, mineral fillers, or mixtures thereof.

8 . The method of claim 1 , wherein the bullet aperture comprises one or more cannelures formed on an inner circumferential surface of the bullet aperture.

9 . The method of claim 1 , wherein the substantially cylindrical coupling region and the polymeric bullet-end coupling are welded or bonded together.

10 . The method of claim 1 , wherein the first polymer composition, the second polymer composition or both comprise polyurethane prepolymer, cellulose, fluoro-polymer, ethylene inter-polymer alloy elastomer, ethylene vinyl acetate, nylon, polyether imide, polyester elastomer, polyester sulfone, polyphenyl amide, polypropylene, polyvinylidene fluoride or thermoset polyurea elastomer, acrylics, homopolymers, acetates, copolymers, acrylonitrile-butadinen-styrene, thermoplastic fluoro polymers, inomers, polyamides, polyamide-imides, polyacrylates, polyatherketones, polyaryl-sulfones, polybenzimidazoles, polycarbonates, polybutylene, terephthalates, polyether imides, polyether sulfones, thermoplastic polyimides, thermoplastic polyurethanes, polyphenylene sulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides, styrene acrylonitriles, polystyrenes, polyphenylene, ether blends, styrene maleic anhydrides, polycarbonates, allyls, aminos, cyanates, epoxies, phenolics, unsaturated polyesters, bismaleimides, polyurethanes, silicones, vinylesters, urethane hybrids, polyphenylsulfones, copolymers of polyphenylsulfones with polyethersulfones or polysulfones, copolymers of poly-phenylsulfones with siloxanes, blends of polyphenylsulfones with polysiloxanes, poly(etherimide-siloxane) copolymers, blends of polyetherimides and polysiloxanes, and blends of polyetherimides and poly(etherimide-siloxane) copolymers.

11 . The method of claim 1 , further comprising a neck positioned between the bullet aperture and the polymeric bullet-end coupling.

12 . The method of claim 11 , further comprising one or more internal structures in the neck to support a bullet.

13 . The method of claim 1 , wherein the bullet aperture comprises one, two, three, or more annular rings that mate with one, two, three, or more corresponding annular grooves positioned on the bullet.

14 . The method of claim 1 , wherein the substantially cylindrical metal primer insert comprises 16-18% Cr; 0-0.05% C; 0-1% Mn; 0-1% Si and the balance Fe.

15 . The method of claim 1 , wherein the substantially cylindrical metal primer insert comprises 2-16% Ni; 10-20% Cr; 0-5% Mo; 0-0.6% C; 0-6.0% Cu; 0-0.5% Nb+Ta; 0-4.0% Mn; 0-2.0% Si and the balance Fe.

16 . The method of claim 1 , wherein the substantially cylindrical metal primer insert comprises 2-6% Ni; 13.5-19.5% Cr; 0-0.10% C; 1-7.0% Cu; 0.05-0.65% Nb+Ta; 0-3.0% Mn; 0-3.0% Si and the balance Fe.

17 . The method of claim 1 , wherein the substantially cylindrical metal primer insert comprises 3-5% Ni; 15.5-17.5% Cr; 0-0.07% C; 3-5.0% Cu; 0.15-0.45% Nb+Ta; 0-1.0% Mn; 0-1.0% Si and the balance Fe.

18 . The method of claim 1 , wherein the substantially cylindrical metal primer insert comprises 10-14% Ni; 16-18% Cr; 2-3% Mo; 0-0.03% C; 0-2% Mn; 0-1% Si and the balance Fe.

19 . The method of claim 1 , wherein the powdered metal comprises 12-14% Cr; 0.15-0.4% C; 0-1% Mn; 0-1% Si and the balance Fe.

20 . The method of claim 1 , wherein the powdered metal comprises 3-12% aluminum, 2-8% vanadium, 0.1-0.75% iron, 0.1-0.5% oxygen, and the remainder titanium.

21 . The method of claim 1 , wherein the powdered metal comprises about 6% aluminum, about 4% vanadium, about 0.25% iron, about 0.2% oxygen, and the remainder titanium

22 . A method of making a polymer ammunition cartridge having a metal injection molded primer insert comprising by the steps of:
forming a substantially cylindrical metal primer insert by metal injection molding from a primer insert injection mold, wherein the substantially cylindrical metal primer insert comprises a top surface opposite a bottom surface and a substantially cylindrical coupling element that extends from the bottom surface, a primer recess in the top surface that extends toward the bottom surface, a primer flash aperture positioned in the primer recess to extend through the bottom surface, and a flange that extends circumferentially about an outer edge of the top surface; providing a first polymer composition for molding a polymer ammunition cartridge; molding from the first polymer composition a substantially cylindrical polymeric middle body having the substantially cylindrical metal primer insert at a first end and a substantially cylindrical polymeric coupling region at a second end, wherein the first polymer composition extends over an outer surface of the substantial

Assignees

• True Velocity Inc

Inventors

• Burrow Lonnie

Classifications

• B22F3/004

  Filling molds with powder (feeding material to presses in general B30B15/302) · CPC title

• C22C38/58

  with more than 1.5% by weight of manganese · CPC title

• C04B35/64

  Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F}) · CPC title

• B22F3/225

  by injection molding · CPC title

• C22C38/18

  containing chromium · CPC title