U.S. patent application number 15/809384 was filed with the patent office on 2018-05-17 for ammunition cartridge with a base plug vent.
The applicant listed for this patent is NOSTROMO HOLDINGS, LLC. Invention is credited to NICOLAS HORACIO BRUNO.
Application Number | 20180135953 15/809384 |
Document ID | / |
Family ID | 62108332 |
Filed Date | 2018-05-17 |
United States Patent
Application |
20180135953 |
Kind Code |
A1 |
BRUNO; NICOLAS HORACIO |
May 17, 2018 |
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.
Inventors: |
BRUNO; NICOLAS HORACIO;
(Cordoba, AR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NOSTROMO HOLDINGS, LLC |
Alexandria |
VA |
US |
|
|
Family ID: |
62108332 |
Appl. No.: |
15/809384 |
Filed: |
November 10, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62422098 |
Nov 15, 2016 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F42B 33/00 20130101;
F42B 5/02 20130101; F42B 39/14 20130101; F42B 33/02 20130101; F42B
39/20 20130101 |
International
Class: |
F42B 39/14 20060101
F42B039/14; F42B 33/00 20060101 F42B033/00; F42B 5/02 20060101
F42B005/02 |
Claims
1. A ammunition cartridge incorporating a projectile inserted in,
and mechanically connected to a metal cartridge case assembly
having an energetic propellant disposed in a combustion chamber;
wherein a base of the cartridge case assembly incorporates a base
plug configured to incorporate a support plug fabricated from a
fusile material that, when completely assembled, the ammunition
cartridge's sub-assembly is filled with a propellant and fit with
an energetic igniter or primer that seals a combustion chamber;
wherein the cartridge case assembly incorporates a cavity and mold
allowing for injection of the fusible material forming the fusible
support plug into the base of the cartridge, during the
manufacturing process to fabricate the cartridge; and wherein said
fusible material loses its strength and structural integrity at
elevated temperatures such that, when the propellant or primer
off-gasses or auto-ignites, the base plug is ejected from the base
of the cartridge, revealing a channel that allows igniting
energetic materials to burn in an unpressurized state and vent
gases to escape into an unconfined space.
2. The ammunition cartridge of claim 1, wherein the fusible
material is a polymer.
3. The ammunition cartridge of claim 1, wherein the fusible
material is a fusible metal.
4. The ammunition cartridge of claim 1, wherein the base plug is
formed of a solid material having a strength at normal munition
operating temperatures that is sufficient to maintain structural
integrity through normal cartridge operating pressures of a
feeding, firing, extraction and ejection cycle of the munition.
5. The ammunition cartridge of claim 1, wherein the auto-ignition
of the propellant vents gases from the void created by ejection of
the base plug.
6. The ammunition cartridge of claim 5, wherein the void is of such
size as to preclude pressurization of the propulsion chamber,
minimizing the imparted energy acting on the projectile affixed to
the cartridge case.
7. The ammunition cartridge of claim 6, wherein the size of the
void, created by ejection of the base plug, is selected to be in
proportion to the type and amount of propellant.
8. The ammunition cartridge of claim 1, wherein the fusible
material forms an O-ring shape surrounding the base plug.
9. The ammunition cartridge of claim 8, wherein the fusible
material surrounding the base plug further includes projection from
the O-ring shape that extends rapidly outward into at least one
passage in the base of the cartridge case, thereby retaining the
physical connection of the base plug to the cartridge case during
ejection after firing and reducing the energy imparted on the
ejection base plug.
10. The ammunition cartridge of claim 1, wherein the internal
cavity is circular in shape; the base includes a plurality of
passages extending radially outward from the internal cavity to the
exterior; and wherein the fusible material includes a plurality of
projections extending radially outward through said passages.
11. An ammunition package for multiple cartridge munitions having a
base plug affixed with fusible material in accordance with claim 1,
wherein said package incorporates packaging material that retains
its form and strength at elevated temperatures and provides an
undeterred vent path for release of pressure in the event the base
plug is ejected.
12. An ammunition package containing multiple cartridges that
incorporate a base vent retained by fusible material in accordance
with claim 1, said package including a dunnage with a configuration
allowing for unobstructed venting of the base of said multiple
cartridges therein and incorporating a blow-out panel in a wall of
the package that relieves any momentary pressurization within the
package by breaking away and allowing gases to vent from a
punctured panel into the atmosphere.
13. The ammunition package of claim 12, wherein the dunnage is
selected so as not to melt and re-congeal or clog vented
cartridges.
14. A method of manufacturing an ammunition cartridge comprised of
a projectile inserted in, and mechanically connected to, a metal
cartridge case having a propulsion chamber and a base, and an
energetic propellant disposed in the propulsion chamber; wherein
the base has a central internal cavity that is provided with an
ejectable, solid base plug in which is mounted an igniter with an
energetic primer; and wherein the base includes at least one
passage from the internal cavity to the exterior; said method
comprising the steps of: (a) inserting a solid base plug into said
internal cavity of the base forming an interface between the base
plug and the base that surrounds it; (b) injecting a fusible
material at an elevated temperature through said at least one
passage into said interface and allowing said fusible material to
solidify at an ambient temperature; and (c) mounting an igniter
with an energetic primer in said base plug.
15. The method of claim 14, wherein the fusible material is a
polymer.
16. The method of claim 14, wherein the fusible material is a
fusible metal.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from the U.S. Provisional
Application No. 62/422,098 filed Nov. 15, 2016.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an ammunition cartridge
incorporating a venting system in the munition's base, a method to
manufacture the cartridge case and a package configuration to store
and transport vented ammunition cartridges.
[0003] Introduction: The term "Insensitive Munitions" refers to a
generic body of munitions knowledge that includes guidance
practices, regulations, technology, methodologies and standards for
complying with the following objective: [0004] "To ensure, to the
extent practicable, that munitions under development or procurement
are safe throughout development and fielding when subject to
unplanned stimuli. IM are those munitions that reliably fulfill
their performance, readiness, and operational requirements on
demand, and that minimize the probability of inadvertent initiation
and the severity of subsequent collateral damage to weapon
platforms, logistic systems, and personnel when subjected to
selected accidental and combat threats." 10 U.S.C. 141, .sctn.
2389
[0005] Insensitive Munitions ("IM") technology includes new
energetic materials with less sensitivity to unplanned stimuli as
well as mechanical and functional designs that mitigate the
undesired reactions against such unplanned stimuli. Two key IM
tests required by the U.S. Department of Defense ("DOD") in
qualification of ammunition are slow cook-off and fast cook-off
tests where the ammunition is exposed to heat and/or fire and the
results are documented. DoD's requirement to identify new safety
technology that can be broadly incorporate into an array of
munitions remains a primary goal, this application focuses on
applying venting solutions in a narrow range of ordnance, gun fired
ammunition cartridges.
[0006] Accordingly, it is desired that an ammunition cartridge will
not exhibit a substantial reaction when naked or packaged
ammunition cartridges are heated when exposed to an external fuel
fire event which is, for the purpose of this specification,
identified as an emergency mode.
[0007] While we intend to introduce new survivability technology
into ammunition cartridges, all cartridges must continue to
function in all normal operational modes, being fired from a cannon
or machine gun. Normal modes of operation include:
[0008] A--Logistics Package Storage
[0009] B--Tactical Stowage
[0010] C--Feeding
[0011] C--Chambering
[0012] D--Function Fire
[0013] E--Extraction
[0014] F--Ejection of a "Spent" cartridge case
[0015] Prior Art: The prior art in the field of Insensitive
Munitions and venting of ammunition propulsion includes a number of
articles and patents that are relevant to the present invention.
Typical of such prior art is the U.S. Pat. No. 5,936,189 to Lubbers
and an article "IM Solutions for Projectiles Crimped to Cartridges
for Artillery Application--Phase II, Transition from Cartridge Case
Venting to Insensitive Propellant" by Carl J. Campagnuolo,
Christine M. Michienzi, Edward G. Tersine, Christine D. Knott,
William J. Andrews--NDIA IM/EM Symposium, May 11-14, 2009.
[0016] Also relevant are the following prior art patents:
[0017] U.S. Pat. No. 7,322,295 (Haeselich) introduced modifications
and configuration of venting cartridge cases using a fusible
material in a channel.
[0018] U.S. Pat. No. 8,028,826 teaches use of a unique internal
packaging configuration for 25 mm ammunition allowing for venting
of cartridge cases using a high density package methodology.
[0019] U.S. Pat. No. 8,322,286 discloses a "contracting" memory
metal incorporated into the base of a projectile's propulsion
allowing for venting.
[0020] U.S. Pat. No. 8,381,656 discloses a cartridge or grenade
venting mechanism that uses interlocking components coupled with a
fusible material that liquefies at elevated temperatures, releasing
a encapsulated spring imparting a rotational force that activates a
vent.
[0021] U.S. Pat. No. 8,550,004 teaches an insensitive cartridge
munition having a base plug in the cartridge case. The base plug is
held in place by a "separate solder" that, at elevated
temperatures, releases the base plug, thus providing a void for
venting propellant gasses.
[0022] U.S. Pat. No. 8,573,127, entitled "Pressure Relief System,"
discloses embodiments for partially or fully encapsulating a
fusible material or plug that loses strength at elevated
temperatures thus providing a method of venting a cartridge
case.
[0023] WO 2012/126554A1, also published as DE 10 2011 014402 A1 and
EP2686636 A1 and B1 disclose a solid base plug crimped or riveted
with a fusible material that is configured in a channel in the
manner taught in U.S. Pat. No. 8,573,127. The device retains the
base plug in position during normal operating conditions, but at
elevated temperatures a bismuth tin material releases the plug from
a channel.
[0024] U.S. Pat. No. 8,720,722, entitled "Venting Mechanism for
Containers," teaches a design to vent containers.
[0025] U.S. Pat. No. 8,925,463 discloses the use of expanding
memory metal, incorporated into a munition's cartridge case, that
releases a base plug with a primer. This patent provides a useful
discussion of the operating context and requirements for cartridge
case operating and venting in emergency storage or cook-off
conditions.
[0026] U.S. Pat. No. 9,410,782 teaches use of an encapsulated
spring fitted into the ogive of a projectile that, upon reaching an
elevated temperature, mechanically separates the fuze from the
warhead, thus venting and separating the detonator or booster from
the primary explosive.
[0027] DE 10 2014 001576 A1 published 2 Feb. 2014 is very similar
to U.S. Pat. No. 8,925,463 as it uses a memory metal in combination
with a fusible material.
[0028] In addition, a great deal of prior art exists for general
use of a base plug in munitions, especially in calibers such as
40.times.53 mm, where fittings for base plugs are often
incorporated into cartridge cases forming dual chamber systems. The
U.S. Army's M169 40.times.53 mm propulsion system has a design,
allowing for loading of the cartridge case during manufacture,
whereby a base plug is fitted to form a high-pressure chamber and,
after a propellant is loaded, the primer is inserted into the base
plug affixed to a cartridge case. In some circumstances it is
advantageous to minimize disruption of well-established supply
chains by swapping out existing crimped base plug designs with
crimped base plug safety vents configured within a base plug.
[0029] Notwithstanding the forgoing references which are applicable
to gun fired ammunition cartridges, most prior art venting concepts
vent other types of munitions such as large artillery projectiles,
bombs, shoulder launched rockets and large tactical rocket
motors.
[0030] When considering venting of ammunition cartridge, some
additional technical context is useful to understand how
propellants react when heated. In most cases, auto-ignition of
propellants in confinement initiates violent deflagration of medium
caliber projectiles.
[0031] Solid Propellant Combustion in Confinement: A principal goal
in Insensitive Munitions (IM) technology development is the
mitigation of violent events where munitions are exposed to
external fires. Most modern military ammunition cartridge use
modern double-based propellants. It is important to understand some
fundamental principles regarding propellants when developing
technologies in this field. There are a number of excellent
teaching references regarding combustion of solid propellants. One
such reference is the NATO publication RTO-EN-023, "Combustions of
Solid Propellants" by G Lengelle, J. Duterque and J. F. Tumbert
from the National Aerospace Research Institute (ONERA) in France,
published in May 2002. This NATO report provides excellent graphics
and detail explaining how propellants will burn at different
efficiency rates with varying atmospheric pressures. When
combustion takes place in a confined state, reactions become more
violent and the reaction releases more energy.
[0032] Fortunately, it is possible to vent combustion chambers,
such that burning propellants do not pressurize combustion
chambers. Hence, venting of a high-pressure chamber in an emergency
condition, such as a fire, leads to reduced energy being released
by unconfined propellant combustion.
[0033] Off-gassing and Differential Thermal Analysis: When
propellants are heated, solid propellants exhibit a phenomenon
known as "off-gassing" or "out-gassing." Double-base gun
propellants typically contain nitrocellulose and nitroglycerine
with small amounts of stabilizers and binders. Nitrogen dioxide
(NO2), a corrosive gas, and other oxides of nitrogen, are generated
in the heating of double-based propellants. The release of results
in increased pressures in a confined environment, but the amount
and types of gases produced by heating vary greatly. The density of
solid propellant in a volume, the type of propellant, age and
storage conditions of the propellant, all influence the amount of
off-gassing exhibited. The amount of off-gassing and pressurization
of a chamber is therefore difficult to predict without exact
control of all the variables.
SUMMARY OF THE INVENTION
[0034] A principal objective of the present invention is to provide
a robust ammunition cartridge configuration that will vent the
propulsion component of ammunition cartridges in order to minimize
collateral damage that results from an auto-igniting propellant
when ammunition cartridges are heated by an external fire.
[0035] It is a further objective of the present invention to
disclose a novel manufacturing process to configure vents
incorporated into the base of ammunition cartridges.
[0036] It is a further objective of the present invention to
provide an improved method for inserting and retaining a base plug
with a venting system into a cartridge munition.
[0037] It is a further objective of the present invention to
provide a cartridge munition that is designed to vent gases under
high pressure from cartridge case and, at the same time, to
physically separate the igniter (primer or flash tube) from the
propellant with the first energetic event.
[0038] It is a further objective of the present invention that,
upon primer initiation (first energetic event) in either a slow or
fast cook-off, a vent mass (base plug) is ejected and an optimized
vent void leads to a less efficient propellant burn (second
energetic event).
[0039] It is a further objective of the present invention to
provide a cartridge munition of the above-noted type with an
effective and reliable solution to vent propellant gases from the
cartridge case in the event the cartridge munition is exposed to
temperatures that reach or exceed auto-ignition temperatures of the
primer, igniter and/or propellant.
[0040] It is yet another objective of the present invention to
provide an ammunition package configuration for cartridge munitions
that facilitates the venting from the ammunition package into the
atmosphere of such munitions fitted with special vent plugs.
[0041] These objectives, as well as additional objectives which
will become apparent from the discussion that follows, are
achieved, according to the invention, by providing a cartridge
munition comprised of a projectile inserted in, and mechanically
connected to, a metal cartridge case having a propulsion chamber
and a base, and an energetic propellant disposed in the propulsion
chamber. The cartridge base has an internal cavity that is provided
with a solid plug in which is mounted an igniter with an energetic
primer. During manufacture of the cartridge, the base plug is
affixed in the cartridge using a process of injection molding a
fusible material through one or more passages into a metal cavity,
where the material cools and forms a fusible support for the plug.
The fully assembled ammunition cartridge functions in normal
operational modes; however, when the cartridge is exposed to
external heating the fusible support for the plug loses mechanical
strength and an unsupported cartridge, clear of obstructions, vents
gases from the base of the cartridge.
[0042] The fusible material, which may be a metal or a polymer, is
selected so that the cartridge case assembly loses mechanical
strength and structural integrity at elevated temperatures such
that, when the propellant or primer off-gasses or otherwise
pressurizes the propulsion chamber, for example, by auto-igniting,
the base plug or lid is ejected from the cavity at the base of the
cartridge case, creating a void that allows the ignited primer or
propellant to burn itself out in an unconfined space.
[0043] A typical ammunition cartridge is comprised of a projectile
inserted into the cartridge case that is mechanically connected
thereto via crimping or alternative means. Normally, a projectile
and cartridge case has a propulsion chambers that contains a solid
propellant. The cartridge case includes a primer or igniter in the
head or base of the cartridge case. The cartridge case may include
one or multiple chambers for ignition, combustion and expansion. A
base plug can be used to close a high pressure chamber in a
cartridge case. Effective combustion of the propulsion requires
containment to optimize burning of the propulsion.
[0044] An objective of this design, according to the invention, in
an emergency situation, is to allow for activation of a vent
creating a channel that is created when the base plug or a base
plug component is ejected from the cartridge case, such that the
vented high pressure chamber precludes auto-igniting propellant
powders from burning in a pressurized environment within a
cartridge case.
[0045] Accordingly, the safer IM cartridge case, when exposed to
heating by a fire, activates an emergency vent that creates a
passage at the base of the cartridge case, where any auto-igniting
energetic materials eject and vent rearward clear of the propulsion
chamber allowing propellant gases to exit through the base plug or
through the head of the cartridge case.
[0046] Where such a system is incorporated into a dual-chamber
propulsion system, and a cartridge is subjected to heating in an
emergency storage mode, the fusible material supporting the base
plug incorporated into the base of a cartridge case weakens.
Off-gassing or combustion of an energetic, such as the propellant,
acts to expel part or all of the base plug from the sealed
cartridge case assembly. This action, in combination, creates an
activated vent channel at the base of the cartridge case.
[0047] It would be beneficial, according to the invention, to also
couple this propulsion venting system, with a methodology to vent
warheads of the type disclosed in the U.S. Pat. No. 9,410,782.
[0048] A cartridge case assembly normally has at least two
non-fusible components. These include: [0049] A cylindrical
cartridge case with a hole at the base for a base plug, and [0050]
A base plug with a pocket for a primer or igniter.
[0051] According to the invention, the contours at the surfaces the
metal non-fusible cylindrical case and a non-fusible base plug
provide a cavity with voids and ports that facilitate injection of
a fusible material into a cavity where the metal parts act to mold
a fusible material. This cavity connects to voids that form one or
more passages that facilitate injection of a heated, fusible fluid
into the cavity during manufacture. Further cooling of the fusible
material to ambient temperatures results in formation of a solid
fusible support for the base plug configured in the cartridge case
assembly. Subsequent ammunition cartridge fabrication steps are
completed in ambient conditions, after injection molding of the
cartridge case and will normally include (1) crimping of the
projectile to a cartridge case, (2) propellant loading and (3)
seating of a primer to close the cartridge case. This fully
assembled ammunition cartridge, configured with a fusible material
supporting the base plug thus incorporates a melting point that is
higher than the operational temperature of the ammunition and lower
than the auto-ignition temperature of the energetics contained in
the cartridge, which may be about 130.degree. C., for example.
[0052] The base plug houses the primer and/or igniter, whereby the
cartridge case assembly: [0053] at normal operating conditions,
remains intact through identify modes of use and function, and
[0054] in an emergency storage condition (when exposed to external
heating) the fusible material liquefies, releasing the base plug
and compromising confinement of the propellant by creating a large
passage or vent hole so that: [0055] (i) the base plug, with a
primer, is ejected rearward from the projectile, and [0056] (ii)
auto-ignition of propellant or primer does not occur in a fixed,
confined volume.
[0057] Accordingly, in the emergency storage condition, the
ignition and expanding gases produced by the burning propellant do
not push the projectile forward from the mouth of the cartridge
case, at a high velocity.
[0058] Where multi-chamber cartridge cases are used, the fusible
material in a heated condition releases the vents from the passage
and (i) does not vent from orifices between multi-chamber systems,
and (ii) does not pressurize the low pressure chamber such that
projectiles are ejected at high-velocity from a projectile's case.
According to the invention, the size of the venting area is chosen
in relation to the propellant load.
[0059] If a cartridge munition of the type described herein is
heated to the melting temperature of the fusible material or
metal--a temperature higher than the operational temperature of the
ammunition but below the auto-ignition temperature of the primer,
igniter or propellant, for example, in the range of about
115.degree. C.--then the fusible material in the void melts. If the
temperature continues to increase and the propellant charte, primer
and/or the igniter auto-ignite, almost no significant pressure can
build up within the propulsion chamber because the opened, free
passages function as pressure-relief apertures.
[0060] According to the invention, the cartridge ejects a base plug
prior to or simultaneous with energetic auto-ignition, such that
combustion occurs in an unconfined space. Propellant combustion in
an unconfined space disrupts efficient propellant combustion and
reduces the violence, severity and shock associated with propellant
auto-ignition. Nevertheless, the disruption of a confined
propellant combustion does not completely render safe the
ammunition and the auto-ignition of solid propellant powders will
still generate gases that must be vented from the rear of the
cartridge case. When ammunition cartridges include high explosive
projectiles, the disclosed method of propulsion venting may be
coupled to a separate, but complementary means of warhead venting
as disclosed in the aforesaid U.S. Pat. No. 9,410,782.
[0061] The ammunition cartridge according to the invention can use
solid metal, polymers or fusible metals in combination. During
manufacture of the cartridge munition, the selected fusible metal
or polymers liquefies at elevated temperatures allowing for
injection via ports into channels and cavities in the cartridge
case. In a preferred embodiment, the fusible material is positioned
substantially outside the venting channel, surrounding the solid
base plug.
[0062] The preferred embodiment of the invention does not use
temperamental rivets and does not use memory metals. The channels,
internally configured by a metal part positioned in a seat, provide
for fabrication of an internal polymer internal skirt, similar to
an O-ring. Cooling of the cartridge case to ambient temperatures
allows the fluid fusible material to solidify during manufacture
such that the metal cartridge case and base plug are bonded
together. After completing the bonding process, the cartridge case
can be loaded with propellant, primer and affixed to a projectile,
thereby forming a completed ammunition cartridge with a safety vent
configured into the base of the cartridge case.
[0063] According to a preferred embodiment of the invention, the
fusible material surrounding the base plug includes a plurality of
outward projections from the O-ring shape that extend radially into
respective openings in the base of the cartridge case. This
"retention feature" retains the physical connection of the base
plug to the cartridge case during ejection after firing and
reducing the energy imparted on the ejected base plug.
[0064] In preferred embodiments of the invention, the fusible
material is selected to lose mechanical strength at an elevated
temperature (1) exceeding the ammunition's maximum storage
temperature, and (2) below the temperature where an energetic,
confined in a high pressure chamber auto-ignites.
[0065] A number of new high-melt temperature polymers can be used
to fabricate vented cartridge cases. In some cases, the molding
ports may be capped or covered.
[0066] The present invention thus provides for an ammunition
cartridge having a metal cartridge case, with a base plug that is
assembled to create and maintain a confined high pressure chamber
within the cartridge case in ambient and operational environments.
The same cartridge munition, when subjected to elevated heating,
ejects the base plug when an energetic primer igniter or the
propellant off-gasses, or an auto-ignition momentarily pressurizes
the high pressure chamber.
[0067] The ammunition cartridge described above is preferably
packaged for transportation and storage in such that combustion
gases discharge through an opened vent, after ejection of the base
plug, such that the vent channel is not impaired. A preferred
embodiment of the packaging arrangement, in accordance with the
present invention, allows for venting gases, released
intermittently from multiple ammunition cartridge undergoing
external heating, allowing for gases to vent from each cartridge
case, into the ammunition storage box, and subsequently from the
temporarily pressurized ammunition storage box into the
atmosphere.
[0068] Accordingly, the packaging material used in ammunition
containers utilizes packing material that retains form and strength
at elevated temperatures and provides an undeterred vent path for
release of pressure in the event the base plug is ejected. The
package preferably includes dunnage with a configuration allowing
for unobstructed venting of the base of the multiple cartridges
contained therein, and includes a blow-out panel in a wall of the
package that relieves any momentary pressurization within the
package by breaking away and allowing gases to vent from a
punctured panel into the atmosphere. Advantageously, the dunnage is
selected so as not to liquefy or clog vented cartridges.
[0069] For a full understanding of the present invention, reference
should now be made to the following detailed description of the
preferred embodiments of the invention as illustrated in the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0070] FIG. 1A shows a perspective, external view of a typical 30
mm.times.173 cartridge detailing typical features.
[0071] 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.
[0072] FIG. 2A depicts a 30 mm cartridge with a "fusible support
plug," according to the invention, incorporated into the base of
the cartridge case.
[0073] FIG. 2B depicts additional details of 30 mm cartridge of
FIG. 2A with a fusible polymer support plug configured in the
cartridge's base.
[0074] 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.
[0075] 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.
[0076] 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.
[0077] 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.
[0078] 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.
[0079] 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.
[0080] 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.
[0081] 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.
[0082] 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.
[0083] 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 IM 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.
[0084] 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
[0085] 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.
[0086] 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.
[0087] 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.
[0088] Modes of Use, Configuration (Unpackaged and Packaged) and
Venting Improvement:
[0089] 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.
[0090] 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.
[0091] Fabrication of Fusible Support Plugs in Cartridge Cases:
[0092] FIG. 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.
[0093] 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.
[0094] 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).
[0095] Incorporation Fusible Support Plugs into Base Plugs:
[0096] 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.
[0097] Heating, Safety Plug and Venting:
[0098] 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.
[0099] 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.
[0100] 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.
[0101] Multi-Chamber Configurations:
[0102] 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.
[0103] References 3A-3E illustrate other 40.times.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.
[0104] 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.
[0105] Form and Injection Molding Fusible Materials into Ports,
Channels and Cavities for Safety Plug Fabrication:
[0106] 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.
[0107] Dunnage and Vented Packaging:
[0108] 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.
[0109] Hot Gun Chamber Performance and Retention Features:
[0110] 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.
[0111] 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
[0112] Ammunition Cartridge Overview [0113] 10 Cartridge [0114] 10A
30 mm Cartridge [0115] 10B 40 mm Cartridge [0116] 12 Projectile
[0117] 12A 30 mm Projectile [0118] 12B 40 mm (HV) Projectile [0119]
14 Cartridge to Projectile Seal [0120] 14A Crimp [0121] 14B O-Ring
[0122] 16 Base Vented Cartridge
[0123] Cartridge Case Assembly Types and Features [0124] 22
Cartridge Case Assembly [0125] 22A 30 mm.times.173 Cartridge Case
Assembly [0126] 22B 40 mm.times.53 Cartridge Case US M169 Assembly
[0127] 22C 40 mm.times.53 Cartridge Case Typical Crimped Assembly
[0128] 22D 40 mm.times.53 Cartridge Case Assembly with Toggle
[0129] 24 Cartridge Case Sub Assembly [0130] 26 Cartridge Case Base
[0131] 26A Crimped Base Plug [0132] 28 Cartridge Case Rim
[0133] Energetic Material [0134] 32A Primer or Igniter [0135] 32B
Flash Tube [0136] 34 Propellant [0137] 36 Combustion gas venting
[0138] 38 Energetic auto-ignition
[0139] Special Propulsion Features [0140] 44 Chamber Wall [0141] 46
High to Low/Interim pressure orifice [0142] 48 Burstable Liner
(Multi-Chamber System)
[0143] Operational Chambers [0144] 52 Single Chamber [0145] 54 Low
Pressure Chamber [0146] 56 High Pressure Chamber
[0147] Typical Metal Propulsion Component Features [0148] 62 Toggle
[0149] 64 Passage [0150] 66 Base Plug Seat [0151] 68 Primer
Seat
[0152] Vent Retention Feature [0153] 72 Crimp, Stake or Wire [0154]
74 Cap
[0155] Safety Vent Features [0156] 82 Safety Vent Cavity [0157] 84
Injection Molding Channels [0158] 86 Fusible Support Plug [0159] 88
Injection Ports for fusible material
[0160] Safety Vent Feature Configured in a Cartridge Case Assembly
[0161] 92 Base with Fusible Support Plug [0162] 92A 30 mm Base and
Fusible Support Plug [0163] 92B 40 mm Base and Fusible Support Plug
[0164] 94 40 mm Base Plug Sub Assembly with inner Safety Vent
Feature [0165] 94A Inner Vent Lid for a Base Plug Assembly [0166]
94B Outer Ring for a Base Plug Assembly [0167] 96 Activated Vent
Channel [0168] 98 Plug sans fusible support
[0169] Ammunition Packaging Features [0170] 102 Packaging Container
[0171] 104 High Temperature Melt Dunnage [0172] 106 Blow-out
panel
[0173] Ammunition States and Modes of Use and Handling [0174] 110A
Mode--Cartridges in packaged condition [0175] 110B Mode--Cartridge
in stowage [0176] 110C Mode--Cartridges in extraction and feeding
[0177] 110D Mode--Cartridges undergoing chambering [0178] 110E
Mode--Cartridges in function fire in gun breach or chamber [0179]
110F Mode--Extraction of "spent" cartridge case [0180] 110G
Mode--Ejection of "spent" cartridge case
[0181] Key Venting Temperature Ranges [0182] 122 Maximum Storage
Temperature [0183] 124 Out gassing Temperature [0184] 126 Phase
Change Temperature [0185] 128 Energetic Event (a) Propellant
Auto-ignition, (b) Primer Auto-ignition or (c) Igniter
Auto-ignition [0186] 129 Melt Temperature of dunnage in packaging
container.
[0187] Heat Transfer [0188] 132 Initial Heating of Cartridge Case
Assembly [0189] 134 Elevated Heating of Cartridge Case Assembly in
a heat soak
* * * * *