Ammunition cartridge with a base plug vent

Abstract

An ammunition cartridge comprised of a projectile inserted in, and mechanically connected to, a metal cartridge case assembly having a propulsion chamber and a base, and an energetic propellant disposed in the propulsion chamber, includes a base plug in which is mounted an igniter with an energetic primer. During manufacture of the cartridge, a fusible support ring is incorporated into a metal cavity. The cartridge base includes a cavity allowing the fusible material to solidify at ambient temperatures. When exposed to heat from an external fire, the fusible support plug liquefies losing its strength and subsequently, when a propellant or primer off-gasses or auto-ignites the pressure from the reaction ejects a metal plug or lid from the cartridge case base, creating a void that allows the propellant and primer to combust in an unconfined space.

Claims

1. A method of manufacturing a base vented ammunition cartridge comprised of a projectile inserted in, and mechanically connected to, a metal cartridge case assembly having a propulsion chamber and a cartridge case base that houses an energetic propellant disposed in the propulsion chamber; wherein the cartridge case base includes at least one fusible support plug that creates a vent channel that is activated only when the cartridge is heated and reaches an elevated temperature; said method comprising the steps of: (a) inserting a plug sans fusible support into a base plug seat, wherein the inserting the plug into the base plug seat forms a safety vent cavity at an inner end of an injection port of the cartridge case base, the safety vent cavity formed partly in the plug and partly in the cartridge case base; (b) injecting a fusible material into the safety vent cavity via the injection port; (c) molding, cooling and solidifying the fusible material at ambient temperature, wherein the cooling and solidifying the fusible material allow the metal cartridge case assembly and the plug to be bonded together; (d) forming a fusible support plug that creates a complete base therewith, and (e) inserting an energetic igniter or primer in a primer seat of the ammunition cartridge.

2. The method of claim 1, wherein the fusible material is a polymer.

3. The method of claim 1, wherein the fusible material is a fusible metal.

4. The method of claim 1, wherein the base vented cartridge case has injection ports via which the fusible material is injected under pressure and injection-molding channels.

5. The method of claim 1, further comprising: inserting a retention feature covering the injection port.

6. The method of claim 1, wherein the fusible support plug is incorporated into the plug using a base plug sub-assembly fabricated with inner safety lid and wherein metal components of the sub-assembly, when partially assembled, provides for mating of an outer ring and the safety lid.

7. The method of claim 6, wherein the outer ring has the injection port allowing for assembly by injection molding of the fusible support plug in the safety vent cavity.

8. The method of claim 1, wherein, when the base vented ammunition cartridge is subjected to high temperature above maximum storage temperature, the fusible support plug softens and when the energetic propellent produces an energetic combustion, the vent channel is activated and releases combustion gases via the vent channel.

9. The method of claim 1, wherein the propellent chamber of the base vented ammunition cartridge comprises a high pressure chamber and a low pressure chamber.

10. The method of claim 9, wherein the propellent chamber includes a toggle that throttles passage of propellant, combustion gases into the low pressure chamber.

11. The method of claim 1, wherein the propellent chamber of the base vented ammunition cartridge comprises a high pressure chamber, a low pressure chamber and an intermediate pressure chamber.

12. The method of claim 11, wherein at least one of the high pressure chamber and an intermediate pressure chamber include an orifice.

13. The method of claim 12, wherein in normal operation, expanding propellant gases combust in the high pressure chamber and channels the gases into the low pressure chamber through the orifice.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A shows a perspective, external view of a typical 30 mm?173 cartridge detailing typical features.

(2) FIG. 1B depicts a perspective cross-sectional view of a typical US 40 mm HV projectile using a US M169 cartridge case assembly. This cartridge case assembly uses a high-low dual chamber system where propellant burns in a high pressure chamber and the pressure at an orifice flows into a low pressure chamber.

(3) FIG. 2A depicts a 30 mm cartridge with a fusible support plug, according to the invention, incorporated into the base of the cartridge case.

(4) FIG. 2B depicts additional details of 30 mm cartridge of FIG. 2A with a fusible polymer support plug configured in the cartridge's base.

(5) FIG. 2C depicts details of the metal body and vent in the cartridge case of the 30 mm cartridge of FIG. 2A, without the fusible material supporting the base plug revealing injection ports and cavities formed by seating and alignment of metal parts.

(6) FIG. 2D is a cross-sectional view of a cartridge exposed to an external fire and activating a safety vent, releasing burning and unconfined propellant gases from the base of the cartridge.

(7) FIG. 3A depicts multiple perspective views of a 40 mm cartridge with a high-low propulsion and fusible polymer safety vent configured in the cartridge case assembly.

(8) FIG. 3B shows cross-sectional views of a typical 40 mm cartridge with a multi-chamber propulsion with a fusible safety vent configured within the cartridge case assembly, setting forth manufacturing steps #1, #2, #3 and #4: #1 being a method step of inserting a plug into a seat, #2 positioning the base plug in a seat, forming a cavity and correctly aligning injection ports, #3 injecting a fusible material such as a polymer or liquid metal into ports to fill the cavity and produce a fusible support plug that congeals upon cooling the assembly, and #4 the steps of (1) loading of propellant and (2) inserting a primer in the sealed external wall of the propulsion chamber that incorporates a fusible plug adjacent to the base of the cartridge.

(9) FIG. 3C depicts images of a U.S. M169 cartridge case with a high-low dual chamber propulsion formed by using modified base plug that incorporates a fusible support plug inside of the base plug.

(10) FIG. 3D depicts additional detail a modified U.S. M169 propulsion including exploded views with a dual chamber high-low propulsion of metal components for a crimped base plug with a fusible support plug.

(11) FIG. 3E depicts cross-section views of a typical Nico type cartridge case with a base plug and fusible support plug incorporated into the base of a cartridge case.

(12) FIG. 4 depicts a perspective, sectioned view of an ammunition packaging container filled with 30 mm ammunition cartridges and dunnage in a logistic package, storage mode. The ammunition box has blow-out panels in a wall section.

(13) FIG. 5 depicts forces and environments at different modes of medium caliber military ammunition, after being unpackaged and loaded into a tactical stowage configuration. Modes of normal use include feeding, chambering, function fire, extraction and ejection typical of cannon and machine gun handling.

(14) FIG. 6 is a graph illustrating how continued heating over time (heat soaking) elevates the temperature of a cartridge. The graph annotates predictable activation and events and nominal temperatures when progressive heating is applied to a cartridge case. An 1M safety vent activates at a predicted temperature prior to an energetic event initiating propellant burn, such that the safety vent is activated to vent gases from the base of a cartridge munition.

(15) FIG. 7 depicts two grey-scale views of a 30 mm cartridge being heated above maximum storage conditions (heat soaking).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(16) The preferred embodiments of the present invention will now be described with reference to FIGS. 1-7 of the drawings. Identical elements in the various figures are designated with the same reference numbers.

(17) To highlight and distinguish the improvement according to the invention from current state of the art, an example of which is illustrated in FIG. 1, FIGS. 2 and 3 depict two typical modes of use for conventional ammunition cartridges 10; namely, a 30 mm configuration and a 40 mm cartridge configuration, respectively. Each cartridge munition 10 incorporates a projectile 12, affixed at 14, to the cartridge case assembly 22.

(18) A typical cartridge is also configured with a propellant 34 that is confined in proximity to the primer or igniter 32A. A typical cartridge case sub-assembly 24 normally includes a rim 28 near the base 26 to facilitate extracting and feeding 110B and cartridge extraction 110E and ejection 110F (FIG. 5). The cartridge case assembly includes the cartridge base 26 that may include a base plug 26A. The improved cartridge according to the invention will continue to function in all modes of use (FIGS. 4 and 5) but will vent the propulsion and/or primer gasses from packaged cartridges when a cartridge or the cartridge package is exposed to heating from an external fire. Desirably, venting will reduce the severity and violence of an energetic event that results from an external fire.

(19) Modes of Use, Configuration (Unpackaged and Packaged) and Venting Improvement

(20) A cartridge munition according to the invention must continue to function in all modes of use (shown in FIG. 5). To this end, such cartridge munitions include a vented cartridge case 16 and improved packaging 102 (shown in FIG. 4) to house the vented cartridge munitions. The packaging provides for a modified logistics storage configuration with special dunnage 104 and blow-out panels 106.

(21) FIG. 2A depicts an improved 30 mm cartridge munition 16 with a projectile 12A and a vented cartridge case 22A. The base of the cartridge case includes a base plug 92A and an incorporated fusible support ring 86. FIG. 2B illustrates how the primer or igniter 32A, are in confined proximity to the propellant 34. The image also depicts an isolated perspective view of the 30 mm base plug 92A incorporating a safety support ring 86 forming a vented cartridge case 22A. A 30 mm cartridge may also include a flash tube 32B to ignite the propellant in the center of the chamber. Typically, a 30 mm cartridge case normally includes one operational chamber filled with propellant 34.

(22) Fabrication of Fusible Support Plugs in Cartridge Cases

(23) FIGS. 2C, 3A and 3B depict key features associated for the production of cartridge case assemblies 22, 22A, 22C, 22D that incorporate a fusible support plug 86 molded into the each cartridge case assembly 22A, 22C and 22D.

(24) FIG. 3B illustrates sequenced production steps #1, #2, #3 and #4 that facilitate fabrication of the fusible support plug according to the invention. Step #1 illustrates how a metal plug, without fusible support 98, is aligned to be inserted to fit to a seat 66 in the cartridge case. In Step #2, the assembly of cartridge case sub-assembly 24 concurrently forms a safety vent cavity 82. In Step #3, a polymer is injected via ports 84 allowing cooling polymer to form in a fusible support plug 86 in a safety vent cavity 82. With the fusible support plug 86 incorporated, after cooling, a manufacturer can in Step #4 load a propellant 34, and fit a primer 92A into a primer seat 68, sealing the high pressure chamber 56 forming a completed cartridge case assembly 22C. FIGS. 2B and 3B illustrate fusible base plugs 86 incorporated into cartridge case assemblies 22.

(25) During assembly, a projectile 12 may be affixed 14 to a cartridge case assembly 22 in either an initial or a final step of fabrication. It is also noteworthy that the assembly process may include insertion of a retention feature or component 72 and a cap 74 (FIG. 2B) covering the injection ports. In Step #4, the propellant is loaded via the primer seat 68 into a high pressure chamber 56 and a primer is positioned in the primer seat 68 closing the projectile and completing fabrication of a base vented cartridge 16 (FIG. 3B). The projectile 12B, assembled to the cartridge case assembly 22C may be sequenced prior to or after Step #4 by use of a seal 14 that may include a crimp 14A or use of an O-ring 14B (FIG. 3A).

(26) Incorporation Fusible Support Plugs into Base Plugs

(27) An alternate construction is provided for in FIGS. 3C and 3D, where a fusible support plug 86 is incorporated into a crimped base plug 26A using a special base plug sub-assembly 94. This sub-assembly is fabricated with inner safety lid 94A. The metal components, when partially assembled, provides for mating of an outer ring 94B and safety lid 94A. Notably, the outer ring has injection ports 88 allowing for assembly by injection molding of a fusible support plug 86 in a safety vent cavity.

(28) Heating, Safety Plug and Venting

(29) FIGS. 1, 2A-D and 3A-E, 6 and 7, in combination, show a safety vent fabrication and contingency vent activation that takes place in an emergency situation where a fire heats ammunition cartridges. In these circumstances, a base vented cartridge 16 will vent gases and burning propellants. Modification of the packaging will allow such a cartridge to vent when stored in a packaged configuration 102. Notably, venting only functions in circumstances when the cartridges or packaged cartridges are exposed to continuous heating imparted by an external fire. In these circumstances a cartridge's temperature rises above the maximum storage temperature 124, and the continuous heat soaks 132 of the cartridge case metal body 22 raises the temperature 134 of the fusible support plug's material 86 above the plug's phase change temperature 126. The resulting phase change (liquefaction) of the fusible material surrounding the base plug compromises the structural integrity of the high pressure chamber. Concurrently, continuous heating of the propellant produces out-gassing pressuring the compartment such that the pressure ejects the plug 26 from the cartridge case assembly 22 creating a vent channel 96.

(30) Alternatively, heating produces propellant auto-ignition event 128 which ejects the base plug 26 to create a clear vent channel 36. A cross-section illustration of the resulting safety vent function is illustrated in FIG. 2D. In these circumstances a vent channel 96 is produced as venting combustion gases 36 escape from the cartridge case assembly 22A at an auto-ignition temperature 128.

(31) Alternatively, where adequate propellant out-gassing occurs at an elevated temperature 124, off-gassing from the propellant pressurizes the chamber and the weakened fusible support plug 92 ejects the plug 98 from the cartridge case assembly 22, 22A, 22B, 22c, 22D. In these circumstances, the base plug 92C is ejected by pressurization of off-gassing (or ignition of combustion gases) 36. As the propellant does not combust in a pressurized vessel, the vent compromises the efficiency of the propellant burn and severity of the energetic event.

(32) Multi-Chamber Configurations

(33) FIG. 3A depicts a 40 mm cartridge with a dual or multi-chamber system with a high pressure chamber 56 and a low pressure chamber 54 where propellant combustion takes place. It is also possible to utilize this methodology for a three chamber propulsion system.

(34) References 3A-3E illustrate other 40?53 mm cartridge configurations with low pressure chamber 54 and high pressure chamber 56 utilizing the techniques identified in this specification. Various configurations may incorporate chamber wall 44, burstable liners 48, and High to Low/Interim Pressure vent orifices 46. A dual chamber case may include a toggle 62 that throttles the passage of propellant, combustion gases into the low pressure chamber 46.

(35) A 40 mm HV cartridge case assembly 22B, 22C and 22D, may include a dual or multi-chamber system with chamber walls 44 where a multi-chamber system includes at least one higher chamber system with a orifice 46. In normal operation, the expanding propellant gases combust in the high pressure chamber bursting a liner 48 or push a toggle component 62 and then pass thru an orifice 46 channeling gases into a low pressure chamber 54. FIG. 3D depicts cross-sectional and perspective views of a preferred cartridge case sub-assembly 24, without energetic components 32A, 32B, 34.

(36) Form and Injection Molding Fusible Materials into Ports, Channels and Cavities for Safety Plug Fabrication

(37) A preferred assembly process forms a multi-chamber cartridge with a high pressure chamber 46 with a safety vent cavity 82 where a fabricator can inject a fusible material, preferably a polymer, via ports 88 and molding channels 84 completing fabrication of a cartridge case sub-assembly 24. In fabrication, such a cartridge case and the incorporated fusible support plugs is held in position within the base plug seat 66. The configuration allows the fabricator to first assemble non-energetic components; in a second step to load the propellant 34 into the high pressure chamber 56 via a passage 64 and, in a third step, position and seal the primer or an igniter 32A allowing for automated assembly of a cartridge case 22.

(38) Dunnage and Vented Packaging

(39) With reference to FIG. 4, it is preferred that in the logistics packaging configuration, combustion gasses are released from the vented cartridge 16, cascading momentarily into a vented packaging container 102, and thereafter transiting and escape into the atmosphere though blow-out panels 106 configured in the packaging 102. The dunnage 104 in a vented packaging container must not melt or clog the cartridge vent channels 26. The combination of base vented cartridges and special dunnage are configured to preclude obstruction of vented cartridges and facilitating transit of gases from the cartridge, into the container and then, via blow-out panels 106, into the atmosphere in a semi-controlled and predictable manner.

(40) Hot Gun Chamber Performance and Retention Features

(41) With reference to FIGS. 2C and 5, a typical cartridge must function in normal operation which can be defined as modes of use and function: logistics storage 110A, feeding 110B, chambering 110C, function fire 110D, extraction 110E and ejection 110F. Open bolt weapons normally have minimal dwell time. Closed bolt weapons, by contrast, may chamber cartridges in a hot gun chamber condition 110C with a dwell time allowing heating of the unfired cartridge. Accordingly, some improved cartridge designs 16 may include a retaining feature 72, 74 or 76 that will preclude inadvertent disintegration during extraction 110E and ejection 110F.

(42) There has thus been shown and described a novel ammunition cartridge fitted with a base plug that will initiate contingent venting which fulfills all the objects and advantages sought therefor. Many changes, modifications, variations and other uses and applications of the subject invention will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawings which disclose the preferred embodiments thereof. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is to be limited only by the claims which follow.

REFERENCE NUMERALS

(43) Ammunition Cartridge Overview 10 Cartridge 30 mm Cartridge 40 mm Cartridge 12 Projectile 12A 30 mm Projectile 12B 40 mm (HV) Projectile 14 Cartridge to Projectile Seal 14A Crimp 14B O-Ring 16 Base Vented Cartridge

(44) Cartridge Case Assembly Types and Features 22 Cartridge Case Assembly 22A 30 mm?173 Cartridge Case Assembly 22B 40 mm?53 Cartridge Case US M169 Assembly 22C 40 mm?53 Cartridge Case Typical Crimped Assembly 22D 40 mm?53 Cartridge Case Assembly with Toggle 24 Cartridge Case Sub Assembly 26 Cartridge Case Base 26A Crimped Base Plug 28 Cartridge Case Rim

(45) Energetic Material 32A Primer or Igniter 32B Flash Tube 34 Propellant 36 Combustion gas venting 38 Energetic auto-ignition

(46) Special Propulsion Features 44 Chamber Wall 46 High to Low/Interim pressure orifice 48 Burstable Liner (Multi-Chamber System)

(47) Operational Chambers 52 Single Chamber 54 Low Pressure Chamber 56 High Pressure Chamber

(48) Typical Metal Propulsion Component Features 62 Toggle 64 Passage 66 Base Plug Seat 68 Primer Seat

(49) Vent Retention Feature 72 Crimp, Stake or Wire 74 Cap

(50) Safety Vent Features 82 Safety Vent Cavity 84 Injection Molding Channels 86 Fusible Support Plug 88 Injection Ports for fusible material

(51) Safety Vent Feature Configured in a Cartridge Case Assembly 92 Base with Fusible Support Plug 92A 30 mm Base and Fusible Support Plug 92B 40 mm Base and Fusible Support Plug 94 40 mm Base Plug Sub Assembly with inner Safety Vent Feature 94A Inner Vent Lid for a Base Plug Assembly 94B Outer Ring for a Base Plug Assembly 96 Activated Vent Channel 98 Plug sans fusible support

(52) Ammunition Packaging Features 102 Packaging Container 104 High Temperature Melt Dunnage 106 Blow-out panel

(53) Ammunition States and Modes of Use and Handling 110A ModeCartridges in packaged condition 110B ModeCartridge in stowage 110C ModeCartridges in extraction and feeding 110D ModeCartridges undergoing chambering 110E ModeCartridges in function fire in gun breach or chamber 110F ModeExtraction of spent cartridge case 110G ModeEjection of spent cartridge case

(54) Key Venting Temperature Ranges 122 Maximum Storage Temperature 124 Out gassing Temperature 126 Phase Change Temperature 128 Energetic Event (a) Propellant Auto-ignition, (b) Primer Auto-ignition or (c) Igniter Auto-ignition 129 Melt Temperature of dunnage in packaging container.

(55) Heat Transfer 132 Initial Heating of Cartridge Case Assembly 134 Elevated Heating of Cartridge Case Assembly in a heat soak