LIGHTWEIGHT POLYMER CASED AMMUNITION

• US 20070261587A1
• Filed: 11/16/2006
• Published: 11/15/2007
• Est. Priority Date: 12/27/2005
• Status: Active Grant

• Current Assignee: Sengshin Chung
• Original Assignee: Sengshin Chung
• Inventors: Chung, Sengshin
• Granted Patent: US 7,610,858 B2
• Time in Patent Office: Days
• US Class Current: 102/469
• CPC Class Codes: F42B 5/313 all elements made of plastics

Abstract

An ammunition cartridge assembled from (1) a substantially cylindrical polymeric cartridge casing body defining a casing headspace with an open projectile-end and an end opposing the projectile-end, wherein the casing body has (A) a substantially cylindrical injection molded polymeric bullet-end component with opposing first and second ends, the first end of which is the projectile-end of the casing body and the second end has a male or female coupling element; and (B) a cylindrical polymeric middle body component with opposing first and second ends, wherein the first end has a coupling element that is a mate for the projectile-end coupling element and joins the first end of the middle body component to the second end of the bullet-end component, and the second end is the end of the casing body opposite the projectile end and has a male or female coupling element; and (2) a cylindrical cartridge casing head-end component with an essentially closed base end with a primer hole opposite an open end with a coupling element that is a mate for the coupling element on the second end of the middle body and joins the second end of the middle body component to the open end of the head-end component; wherein the middle body component is formed from a material more ductile than the material head-end component is formed from but equal or less ductile than the material the bullet-end component is formed from. Methods for assembling ammunition cartridges and ammunition cartridges having the headspace length larger than the corresponding headspace length of the chamber of the intended weapon measured at the same basic diameter for the cartridge casing without being so large as to jam the weapon or otherwise interfere with its action are also disclosed.

Claims

1. An ammunition cartridge comprising:

(1) a substantially cylindrical polymeric cartridge casing body defining a casing headspace, with an open projectile-end and an end opposing the projectile-end, said casing body comprising;

(A) a substantially cylindrical injection molded polymeric bullet-end component with opposing first and second ends, the first end of which is the projectile-end of the casing body and the second end comprises a male or female coupling element; and

(B) a cylindrical polymeric middle body component with opposing first and second ends, wherein said first end comprises a coupling element that is a mate for said projectile-end coupling element joining said first end of said middle body component to said second end of said bullet-end component, and said second end is said end of said casing body opposite said projectile end and comprises a male or female coupling element; and

(2) a cylindrical cartridge casing head-end component comprising an essentially closed base end with a primer hole opposite an open end comprising a coupling element that is a mate for said coupling element on said second end of said middle body component joining said open end of said head-end component to said second end of said middle body component;

wherein said middle body component is formed from a material that is more ductile than the material from which said head-end component is formed but equal or less ductile than the material from which said bullet-end component is formed.

2. The ammunition cartridge of claim 1, wherein either or both of said bullet-end component and said middle body component is formed from a ductile polymer.

3. The ammunition cartridge of claim 2, wherein said middle body component is formed from a fiber-reinforced polymeric composite.

4. The ammunition cartridge of claim 3, wherein aid fiber-reinforced polymeric composite contains between about 10 and about 70 wt % glass fiber fillers, mineral fillers, or mixtures thereof.

5. The ammunition cartridge of claim 1, wherein said bullet-end component and said middle body component are formed from the same polymer.

6. The ammunition cartridge of claim 1, wherein said bullet-end component and said middle body component are formed from different polymers.

7. The ammunition cartridge of claim 1, wherein both coupling elements on said middle body component are male coupling elements.

8. The ammunition cartridge of claim 1, wherein both coupling elements on said middle body component are female coupling elements.

9. The ammunition cartridge of claim 1, wherein one coupling element on said middle body component is a male coupling element and the other is a female coupling element.

10. The ammunition cartridge of claim 9, wherein said first end of said middle body component comprises a female coupling element and said second end of said bullet-end component comprises a male coupling element dimensioned to snap-fit or interference fit within and engage said female coupling element of said middle body component, and said second end of said middle body component comprises a male coupling element and said open end of said head-end component comprises a female coupling element and said male coupling element of said middle body component is dimensioned to fit or snap-fit or interference fit within and engage said female coupling element of said head-end component.

11. The ammunition cartridge of claim 10, wherein said male coupling element of said bullet-end component and said female coupling element of said middle body component are welded or bonded together.

12. The ammunition cartridge of claim 1, wherein said bullet-end component and said middle body component comprise the same or different polymers selected from the group consisting of 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.

13. The ammunition cartridge of claim 1, wherein said head-end component is formed from high strength polymer, fiber-reinforced polymer composite, ceramic or metal.

14. The ammunition cartridge of claim 13, wherein said head-end component is formed from a metal selected from the group consisting of aluminum, steel and brass.

15. The ammunition cartridge of claim 10, wherein said head-end component is formed from aluminum, said middle body component is formed from a fiber-reinforced polymer composite and the second end of said middle body component comprises an essentially closed base end with a primer flash hole.

16. The ammunition cartridge of claim 1, wherein said head-end component is formed from steel or brass, said middle body component is formed from a fiber-reinforced polymer composite or a ductile polymer and the second end of said middle body component comprises an essentially closed base end with a primer flash hole.

17. The ammunition cartridge of claim 15 or claim 16, wherein said middle body component is injection molded into said head-end component.

18. The ammunition cartridge of claim 15 or claim 16, wherein said middle body component is snap-fit into said head-end component.

19. The ammunition cartridge of claim 15 or claim 16, wherein said bullet-end component is formed from a ductile polymer that is welded or bonded to said middle body component.

20. The ammunition cartridge of claim 19, wherein said ductile polymer has one or more of the following mechanical properties:

Yield or tensile strength at −

65°

F.>

10,000 psi

Elongation-to-break at −

65°

F.>

15%

Yield or tensile strength at 73°

F.>

8,000 psi

Elongation-to-break at 73°

F.>

50%

Yield or tensile strength at 320°

F.>

4,000 psi

Elongation-to-break at 320°

F.>

80%;

and said middle body component is formed from a polymer having one or more of the following mechanical properties;

Yield or tensile strength at −

65°

F.>

10,000 psi

Yield or tensile strength at 73°

F.>

8,000 psi and

Yield or tensile strength at 320°

F.>

4,000 psi.

21. The ammunition cartridge of claim 1, wherein said bullet-end component is formed from a polymer having one or more of the following mechanical properties:

Yield or tensile strength at −

65°

F.>

10,000 psi

Elongation-to-break at −

65°

F.>

15%

Yield or tensile strength at 73°

F.>

8,000 psi

Elongation-to-break at 73°

F.>

50%

Yield or tensile strength at 320°

F.>

4,000 psi

Elongation-to-break at 320°

F.>

80%;

and said middle body component is formed from a polymer having one or more of the following mechanical properties;

Yield or tensile strength at −

65°

F.>

10,000 psi

Yield or tensile strength at 73°

F.>

8,000 psi and

Yield or tensile strength at 320°

F.>

4,000 psi.

22. The ammunition cartridge of claim 20 or claim 21, wherein at least one of said bullet-end component polymer and said middle-body component polymer has all of said mechanical properties.

23. The ammunition cartridge of claim 10, wherein said female coupling element of said head-end component is formed with a straight skirt interlock surface with at least one annular groove and said male coupling element of said middle body component is formed with a straight interlock surface with at least one annular ring dimensioned to fit within and engage an annular groove of said female coupling element of said head-end component to provide a fit or snap-fit or interference fit or mechanical interlock engagement between the two components.

24. The ammunition cartridge of claim 10, wherein said female coupling element of said middle body component is formed with a tapered skirt end and a straight interlock surface with at least one annular groove and said male coupling element of said bullet-end component is formed with a tapered end and a straight interlock surface with at least one annular ring dimensioned to fit within and engage an annular groove of said female coupling element of said middle body component to provide a snap-fit interlock engagement between the two components.

25. The ammunition cartridge of claim 10, wherein said male coupling element of said bullet-end component is formed with a straight interlock surface that tapers to a smaller diameter at the coupling element tip, and said female coupling element of said middle body component is formed with a straight interlock surface that tapers to a smaller diameter at the forward portion on the skirt tip.

26. The ammunition cartridge of claim 10, wherein said inner diameter of said female coupling element of said middle body component is equal or smaller than the outer diameter of said male coupling element of said bullet-end component.

27. The ammunition cartridge of claim 25, wherein said tapered skirt interlock surface of said female coupling element of said middle body component is formed with at least one annular groove and said interlock surface of said male coupling element of said bullet-end component is formed with at least one annular ring dimensioned to fit within and engage an annular groove of said female coupling element to provide a snap-fit interlock engagement between the two components.

28. The ammunition cartridge of claim 10, wherein said male coupling element of said middle body component is formed with a straight interlock surface that tapers to a smaller diameter at the coupling element tip, and said female coupling element of said head-end component is formed with a straight skirt interlock surface that tapers to a smaller diameter at the forward portion on the skirt tip.

29. The ammunition cartridge of claim 28, wherein said tapered skirt interlock surface of said female coupling element of said head-end component is formed with at least one annular groove and said interlock surface of said male coupling element of said middle body component is formed with at least one annular ring dimensioned to fit or snap-fit within and engage an annular groove of said female coupling element to provide a fit or snap-fit or interference fit or mechanical interlock engagement between the two components.

30. The ammunition cartridge of claim 1, wherein said bullet-end, middle body and head-end component define the interior of a powder chamber.

31. The ammunition cartridge of claim 30, wherein said bullet-end component comprises a neck from the case shoulder of the cartridge to the opening at said projectile end and said projectile end opening has an inner diameter no more than 0.002 inches larger than but no more than 0.008 inches smaller than the intended projectile diameter.

32. The ammunition cartridge of claim 30, wherein the inner diameter of said bullet-end component narrows within said casing neck to form an interior shoulder supporting said casing neck and said casing neck interior tapers to an inner diameter at said shoulder between about 0.002 and about 0.025 inches smaller than said projectile diameter.

33. The ammunition cartridge of claim 30, wherein said neck and shoulder comprise a plurality of internal structures for supporting a projectile.

34. The ammunition cartridge of claim 30, wherein said bullet-end component is molded with a plurality of internal ribs affixed to said neck and shoulder for supporting a projectile

35. The ammunition cartridge of claim 32, wherein said neck and shoulder define an annular inner recess for supporting a projectile.

36. The ammunition cartridge of claim 32, further comprising a particulate or consolidated propellant charge in said powder chamber and a projectile inserted into said casing to the base of said casing neck.

37. The ammunition cartridge of claim 36, wherein said projectile has an annular groove positioned to receive the tip of said casing mouth.

38. The ammunition cartridge of claim 37, wherein said casing mouth is crimped at said tip so that polymeric material at said tip flows into said annular groove of said projectile.

39. The ammunition cartridge of claim 31, wherein said casing neck interior tapers to an inner diameter at the base of said casing neck between about 0.002 and about 0.025 inches smaller than said projectile diameter.

40. The ammunition cartridge of claim 39, wherein said neck comprises a plurality of internal structures for supporting a projectile.

41. The ammunition cartridge of claim 40, wherein said bullet-end component is molded with a plurality of internal ribs affixed to said neck for supporting a projectile

42. The ammunition cartridge of claim 39, wherein said neck defines an annular inner recess for supporting a projectile.

43. The ammunition cartridge of claim 39, further comprising a particulate or consolidated propellant charge in said powder chamber and a projectile inserted into said casing beyond the base of said casing neck.

44. The ammunition cartridge of claim 43, wherein said projectile has an annular groove positioned to receive the tip of said casing mouth.

45. The ammunition cartridge of claim 44, wherein said casing mouth is crimped at said tip so that polymeric material at said tip flows into said annular groove of said projectile.

46. The ammunition cartridge of claim 43, wherein said casing neck interior tapers to an inner diameter at the base of said casing neck between about 0.002 and about 0.025 inches smaller than said projectile diameter.

47. The ammunition cartridge of claim 1, wherein said casing headspace is dimensioned larger than the corresponding headspace dimension of the chamber of the intended weapon measured at the same basic diameter for the cartridge casing at 73°

F., without being so large as to jam the weapon or otherwise interfere with its action.

48. The ammunition cartridge of claim 47, wherein said casing headspace is between about 0.001 and about 0.030 inches larger than said corresponding headspace dimension of the intended weapon chamber.

49. A method for assembling an ammunition cartridge comprising:

(1) mating a cylindrical cartridge casing head-end component having an essentially closed base end with a primer hole opposite an open end having a coupling element to a cylindrical polymeric middle body component with opposing first and second ends, wherein the first end has a male or female coupling element and the second end has a coupling element that is a mate for said coupling element of said head-end component;

(2) providing a substantially cylindrical injection molded polymeric bullet-end component with opposing first and second ends, said first end of which is the projectile-end of said ammunition cartridge and said second end has a coupling element that is a mate for said coupling element on said first end of said middle body component; and

(3) mating said first end of said middle body component to said second end of said bullet-end component; and

wherein said middle body component is formed from a material that is more ductile than the material from which said head-end component is formed but equal or less ductile than the material from which said bullet-end component is formed.

50. The method of claim 49, wherein said step of mating said middle body component to said head-end component comprises injection molding said middle body component onto said head-end component.

51. The method of claim 49, wherein said step of mating said middle body component to said head-end component comprises snap-fitting said middle body component onto said head-end component.

52. The method of claim 51, further comprising the step of bonding said middle body component to said head-end component.

53. The method of claim 49, wherein said step of mating said middle body component to said bullet-end component comprises snap-fitting or interference fitting said bullet-end component onto said middle body component.

54. The method of claim 53, further comprising the step of welding or bonding said middle body component to said bullet-end component.

55. The method of claim 49, further comprising the steps of filling said cartridge casing with propellant and joining said cartridge casing to a projectile.

56. The method of claim 55, wherein said filling step comprises filling consolidated propellant powder into said bullet-end component prior to welding or bonding said bullet-end component with said middle body component.

57. The method of claim 55, wherein said filling and joining steps are performed in-line.

58. The method of claim 55, wherein said filling and joining steps are performed at a remote location.

59. An ammunition cartridge comprising:

(1) a one-piece substantially cylindrical polymeric cartridge casing body defining a casing headspace, with an open projectile-end and an end opposing the projectile-end with a male or female coupling element; and

(2) a cylindrical metal cartridge casing head-end component comprising an essentially closed base end with a primer hole opposite an open end comprising a coupling element that is a mate for said coupling element on said opposing end of said polymeric cartridge casing body joining said open end of said head-end component to said to said opposing end of said polymeric cartridge casing body;

wherein said polymeric cartridge casing body is formed from a polymer having one or more of the following properties;

Yield or tensile strength at −

65°

F.>

10,000 psi

Elongation-to-break at −

65°

F.>

15%

Yield or tensile strength at 73°

F.>

8,000 psi

Elongation-to-break at 73°

F.>

50%

Yield or tensile strength at 320°

F.>

4,000 psi

Elongation-to-break at 320°

F.>

80%.

60. The ammunition cartridge of claim 59, wherein at least one of said bullet-end component polymer and said middle-body component polymer has all of said mechanical properties.

61. The ammunition cartridge of claim 59, wherein said polymer is selected from the group consisting of polyphenylsulfones, copolymers of polyphenylsulfones with polyethersulfones or polysulfones, copolymers of polyphenylsulfones 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.

62. The ammunition cartridge of claim 59, wherein said one-piece substantially cylindrical polymeric cartridge casing body and said cylindrical metal cartridge casing head-end component define a shotgun shell.

63. The ammunition cartridge of claim 59, wherein said casing headspace is dimensioned larger than the corresponding headspace dimension of the chamber of the intended weapon measured at the same basic diameter for the cartridge casing at 73°

F., without being so large as to jam the weapon or otherwise interfere with its action.

64. The ammunition cartridge of claim 59, wherein said casing headspace is between about 0.001 and about 0.030 inches larger than said corresponding headspace dimension of the intended weapon chamber.