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Lightweight ammunition articles comprising a polymer cartridge case

A technology of polymers and thermoplastic polymers, which can be used in the direction of cartridge ammunition, ammunition, offensive equipment, etc., and can solve the problems that hinder the direct replacement of brass, a polymer material.

Pending Publication Date: 2021-03-16
SHPP GLOBAL TECH BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are a number of hurdles that prevent polymeric materials from serving as drop-in replacements for brass, the biggest of which is the temperature range in which they must function

Method used

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  • Lightweight ammunition articles comprising a polymer cartridge case
  • Lightweight ammunition articles comprising a polymer cartridge case
  • Lightweight ammunition articles comprising a polymer cartridge case

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0100] The mechanical, thermal and rheological properties of Comparative Samples A-D and Inventive Samples 1 and 2 were evaluated and the results are shown in Table 2.

[0101] Table 2.

[0102]

[0103]

[0104] Inventive Sample 1, with a tensile yield strength of 7.7 Kpsi (53 MPa) and a modulus of 295 Kpsi (2033 MPa), had the lowest strength and stiffness of all the materials evaluated and was 48% and 56% lower than Comparative C, respectively. The yield strength of Comparative Sample D is similar to that of Inventive Sample 1, with only a 14% increase, while the tensile modulus of Comparative Sample A is 13% higher than that of Inventive Sample 1. Inventive Sample 1 has a tensile elongation at break of 99% compared favorably to Comparative Sample A's 95%, while all other unfilled materials have a tensile elongation at break of 40% to 80%. The addition of molded glass to Inventive Sample 2 incrementally increased the tensile strength or modulus while reducing the elon...

Embodiment 2

[0108] This example evaluates the material's resistance to impact shock cracking as a function of temperature, and the presence or absence of defined notches in impacted test specimens. Record the failure mode of the impacted specimens and report the percentage of the total number of specimens tested that failed in a ductile manner. Notched Izod testing provides a material's response to a sudden impact, which simulates the pressure burst that a polymer casing of an ammunition article would experience during a firing event.

[0109] The notched Izod impact (NII) properties and percent ductility of Comparative Samples A to D and Inventive Samples 1 and 2 were evaluated as a function of temperature. The results are shown in Table 3.

[0110] table 3.

[0111]

[0112] The results in Table 3 show that Inventive Sample 1 was the most impact resistant and ductile material evaluated at all temperatures, with notched Izod impact values ​​ranging from 17.6 ft-lbf / 12.1ft-lbf / in t...

Embodiment 3

[0115] This example evaluates the tensile properties of the material at high strain rates that more accurately represent conditions during a firearm firing event. Gun pressure increases rapidly, characterized by reaching 60Kpsi (413MPa) in less than 400ms. This in turn leads to very high strain rates on the polymer cartridge shell. Typical target strain rates range from 480 to 48000 mm / min compared to ASTM tensile test strains of 5 to 50 mm / min for thermoplastics. The ability of a material to handle such high strain rates at application temperatures of -40°F (-40°C), 74°F (23°C) and 165°F (74°C) has attracted attention. Tensile properties at high strain rates were evaluated for Comparative Samples A-C and Inventive Sample 1 . The results are summarized in Tables 4A-4I.

[0116] Table 4A.

[0117]

[0118]

[0119] Table 4B

[0120]

[0121] Table 4C.

[0122]

[0123] Table 4D.

[0124]

[0125] Table 4E.

[0126]

[0127] Table 4F.

[0128]

[01...

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Abstract

An ammunition article comprises a polymer cartridge case formed of a polymer composition comprising a thermoplastic polymer, preferably the polymer composition having a density of less than 1.35 determined in accordance with ASTM D792, the polymer cartridge case having a first end, an opposing second end, and a chamber disposed between the first end and the second end for receiving a propellant; aprojectile attached to the first end of the polymer cartridge case; a metal base insert joined to the second end of the polymer cartridge case; and a primer carried by the metal base insert; whereinthe metal base insert and the polymer cartridge case remain joined together as a single piece assembly upon loading, firing and removal from a chamber of a firearm for a polymer case temperature of -65 DEG F (-54 DEG C) to 165 DEG F (74 DEG C).

Description

technical field [0001] The present invention relates to ammunition articles, and in particular to lightweight ammunition articles comprising polymer casings. Background technique [0002] Small arms ammunition cartridges are used in a variety of firearms, from pistols to rifles and shotguns to heavy automatic weapons. Ammunition cartridges generally include casings, bullets, cartridge primers and propellant powder or gunpowder. Some ammo casings use aluminum or steel, however, nearly all conventional ammunition casings are made of brass alloys. The military needed to reduce the weight of ammunition to lighten the combat burden on soldiers without sacrificing the performance and handling capabilities of brass. Polymers are lightweight compared to brass. However, there are a number of hurdles preventing polymeric materials from serving as a drop-in replacement for brass, the biggest of which is the temperature range in which they must function. In particular, the low tempe...

Claims

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Application Information

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IPC IPC(8): F42B5/307
CPCF42B5/307
Inventor 马克·A·桑纳埃内斯特·福德·考德威尔查尔斯·帕吉特克里斯托弗·沃尔杰罗尔德·哈丁兰塞·帕吉特
Owner SHPP GLOBAL TECH BV
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