US20180321020A1

US20180321020A1 - Flexible pressure vessel for assembled ammunition casing

Info

Publication number: US20180321020A1
Application number: US15/969,453
Authority: US
Inventors: Peter Evans
Original assignee: EVANS FINDINGS COMPANY Inc
Current assignee: EVANS FINDINGS COMPANY Inc
Priority date: 2017-05-03
Filing date: 2018-05-02
Publication date: 2018-11-08
Also published as: WO2018204510A1

Abstract

An ammunition case includes an elongate interior cavity for receiving a propellant and a projectile and extending along a longitudinal axis between a top end and a bottom end, and a bottom corner of the cavity having a reversed radius design supported by a shaped base.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit from U.S. Provisional Patent Application Ser. No. 62/500,786, filed May 3, 2017, and U.S. Provisional Patent Application Ser. No. 62/553,578, filed Sep. 1, 2017, both of which are incorporated by reference in their entireties.

STATEMENT REGARDING GOVERNMENT INTEREST

None.

BACKGROUND OF THE INVENTION

The present invention relates to ammunition articles, and more particularly to a flexible pressure vessel for an assembled ammunition casing.
Firearm ammunition cartridges typically include a casing holding the projectile or bullet, a propellant, such as gunpowder or cordite, and an igniting means including a primer or igniting medium. Thus, the casing is used as a container for functionally holding together and arranging the other cartridge components. In general, because of the extreme nature of the application, materials used for fabrication of ammunition cartridges must demonstrate excellent mechanical properties. Ammunition for civilian and military use has been built using single piece brass casings for one hundred fifty years. Other materials such as aluminum and steel have also been used in efforts to reduce price or has alternate supply when the copper supply becomes tight. However, very little effort has gone into casing improvement over the years.
It has been desirable in the cartridge design to improve the pressure withstanding capability of the casing. Recent developments in two piece casings have brought promise. A casing is already marketed having a stainless pressure vessel mated to an aluminum alloy base. However, one of the limiting factors is increased pressure is the ability of the bottom corner of the pressure vessel to withstand the desired higher pressures. The lower corner of the tube is the weakest part of the design.
What is needed is an improvement apparatus to overcome these and other shortcomings.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the innovation in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
In general, in one aspect, the invention features an ammunition case including an elongate interior cavity for receiving a propellant and a projectile and extending along a longitudinal axis between a top end and a bottom end, and a bottom corner of the cavity having a reversed radius design supported by a shaped base.
In another aspect, the invention features an ammunition case including an elongate interior cavity for receiving a propellant and a projectile and extending along a longitudinal axis between a top end and a bottom end, and a bottom corner of the cavity having a broad radius design supported by a shaped base.
In still another aspect, the invention features an ammunition case including an elongate interior cavity for receiving a propellant and a projectile and extending along a longitudinal axis between a top end and a bottom end, and a bottom corner of the cavity having an angle/radius combination supported by a shaped base.
In another aspect, the invention features an ammunition case including a case, the case having a wall deformed in a pattern of deformations directed inwardly, enabling a balance of outer profile maintenance for general loading and handling while giving spring characteristics of in an axial direction.
In another aspect, the invention features an ammunition case including an elongate interior cavity for receiving a propellant and a projectile and extending along a longitudinal axis between a top end and a bottom end, and having one or more grooves rolled into the sidewall above a bottom corner.
These and other features and advantages will be apparent from a reading of the following detailed description and a review of the associated drawings. It is to be understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of aspects as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings where:

FIGS. 1A and 1B show cross sectional views of prior art cartridges casings for firearm ammunition.

FIG. 2 is a cross-sectional view of a first embodiment of an exemplary ammunition case.

FIG. 3 is a cross-sectional view of a second embodiment of an exemplary ammunition case.

FIG. 4 is a cross-sectional view of a third embodiment of an exemplary ammunition case.

FIG. 7 is a cross-sectional view of a fourth embodiment of an exemplary ammunition case.

FIG. 6 is a cross-sectional view of a fifth embodiment of an exemplary ammunition case.

FIG. 7 is a cross-sectional view of a sixth embodiment of an exemplary ammunition case.

DETAILED DESCRIPTION

The subject innovation is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It may be evident, however, that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the present invention.
As shown in FIG. 1A, an exemplary prior art cartridge casing 1 is elongate and is constituted by a plate shaped bottom wall and a sidewall 3 extending upwardly generally perpendicularly from the bottom wall 2. Thus, the casing 1 is hollow and defines an elongate interior cavity 4. The bottom wall 2 has a circular shape, and, accordingly, the sidewall 3 has cylindrical symmetry about a longitudinal axis 5 of the casing 1 and the cavity 4.
The sidewall 3, which is an elongate tubular portion, includes in longitudinal direction sections 6 a and 6 b having different diameters and a corresponding transition region 6 c between the lower, larger diameter section 6 b and the upper, smaller diameter section 6 a. The sections 6 a and 6 b may or may not be slightly tapered in the longitudinal direction, in particular in a direction away from the bottom wall 2.
The bottom wall 2 includes a through bore 7 which extends in a longitudinal direction and has a lower, large diameter section 7 a extending from a lower axial end surface 8 of the bottom wall 2 and an upper, small diameter section 7 b.
The casing 1 is composed of two separate elements or components, namely an elongate tubular sleeve component 10 and a bottom component 11, which are mechanically secured to each other. The sleeve component 10 is not identical with the elongate tubular portion forming the sidewall 3, but that the sleeve component 10 also forms a relatively small portion of the bottom wall 2. Consequently, while the bottom component 11 forms nearly all of the bottom wall 2, it does not form the entire bottom wall 2.
The material from which the sleeve component 10 is constructed is of a considerably lower thickness than the material from which the bottom component 11 is constructed. Thus, the thickness of the sleeve component 10 throughout its entire extension is smaller than the thickness of the entire bottom component 11, with the exception of a portion 16. In particular, the thickness contribution provided by the bottom component 11 to the total thickness of the bottom wall 2 in the longitudinal direction is considerably larger than the material thickness anywhere in the sleeve component 10.
For allowing a simple mechanical attachment of the bottom component 11 to the sleeve component 10, the sleeve component 10 is formed such that at its lower end 12 it includes a radially inwardly projecting annular flange 13, the lower surface 14 of which constitutes an annular lower axial end surface or bottom surface of the sleeve component 10. The surface 14 is the lowermost portion of the sleeve component 10, i.e. the lower terminal axial end thereof. This bottom surface 14 of the sleeve component 10 is arranged in abutment with a corresponding annular upper axial end surface 15 of the bottom component 11 and may be attached thereto by suitable means.
The attachment is effected by the annular bent-back portion 16 of the bottom component 11, which extends in parallel to and at a certain axial distance from the annular upper axial end surface 15 of the bottom component 11 in the immediate vicinity of the through bore 7. The annular flange 13 of the sleeve component 10 is arranged to extend into the annular space defined by the end surface 15 and the bent-back portion 16 of the bottom component 11, and the sleeve component 10 is thereby locked in place and securely retained on the bottom component 11 in the position illustrated. Due to the mating construction of the annular bent-back portion 16 of the bottom component 11 and of the annular flange 13 of the sleeve component 10, the sleeve component 10 and the bottom component 11 are self-centering upon assembly.
The bottom component 11 has the shape of a planar ring. In the longitudinal direction it includes two adjacent sections 17 a, 17 b having different diameters and forming a sharp rectangular step 19 between them. Thus, the bottom component 11 includes a lowermost annular projection 18 radially outwardly projecting as compared to the recessed portion 17 b and actually the entire remainder of the bottom component 11. A lower end 12 of the sleeve component 10 and, consequently, the peripheral outer edge 20 of the annular flange 13 of the sleeve component 10 has a diameter which is larger than the diameter of the recessed portion 17 b of the bottom component 11 and is identical or substantially identical to the diameter of the annular projection 18 of the bottom component 11. Due to this construction, an annular groove 21 is present in the radial outer surface of the bottom component 11, wherein the borders or sidewalls of this groove 21 are formed by the two steps 19 and 20. In the assembled cartridge the groove 21 serves as the extractor groove for extracting the empty casing 1 from the firing chamber of the firearm following actuation thereof.
It is also possible for the section 17 b to have the same or essentially the same radial diameter than the or a lower end 12 of the sleeve component 10 and, consequently, the peripheral outer edge 20 of the annular flange 13 of the sleeve component 10. In such a case, the cartridge casing 1 does not include an extractor groove, but the annular projection 18 at the very bottom of the bottom component 11 and the step between the projection 18 and the recessed portion 17 b is provided for engagement by an extraction mechanism.
As can be seen in FIG. 1B, another prior art ammunition case 100 includes a sharp corner 102 and is an area of stress concentration. High stress is created during firing as the case sidewall 104 is held to the breach by friction and the bottom is acted on by internal case pressure. The sharp corner 102 is an area where the motion of the sidewall radially to the breach wall is discontinuous from the motion of the bottom axially away from the interior of the case. The compression of the aluminum base allows enough motion for the corner to fail at high case pressure. More specifically, it is a combination of the compression of the base and the breach head space along with the friction traction on the sidewall that require that the case sidewall be able to stretch to conform to the breach interior volume. Head space is the breach cavity design allowance that exceeds the loaded cartridge length and allows the cartridge to fit loosely in length into the closed breach cavity.
The problem is made worse by a design that requires an internal corner radius of less than the material thickness. Forming this radius necessarily reduces the cross sectional thickness in the are of the radius further reducing the load carrying capability. Thus, the sharp corner 102 is the area where the motion of the sidewall radially to the breach wall is discontinuous from the motion of the bottom axially away from the interior of the case.
As shown in FIG. 2, a first embodiment of an ammunition case 200 of the present invention includes a bottom corner 202 of a cavity 204 having a reversed radius design supported by the shaped base. The support of the aluminum base prevents failure at high case pressure.
As shown in FIG. 3, a second embodiment of an ammunition case 300 of the present invention includes a bottom corner 302 of the cavity 304 having a broad radius 306 supported by the shaped base. Here again, support of this aluminum base prevents failure at high case pressure.
As shown in FIG. 4, a third embodiment of an ammunition case 400 of the present invention includes a bottom corner 402 of a cavity 404 having an angle/radius combination 406 supported by the shaped base. With this design, support of this aluminum base prevents failure at high case pressure.
Other embodiments of the present invention further enable an ability of a bottom corner of a pressure vessel to withstand high pressures. In FIG. 5, an ammunition case 500 exhibits a geometry in a case 502 wall that enables axial expansion of the case wall 502 so that it can travel with a base 504 during a high pressure event to where it is ultimately still supported by the base 504 at full travel. To accomplish this, the exterior of the case wall 502 is deliberately deformed in a lower area during manufacturing to construct a spring wall section 506. The spring wall section 506 has curvilinear path to the barrel wall and extends to travel with the compressed base 504 without exceeding a tensile or shear load of the case wall 502 at or near a corner.
Various geometries of “spring” can be built into the casing 502 to tune it to a desired performance. The enables manufacture of thin wall and/or light weight casings to use thinner and/or lower strength materials. While prior designs have used austenitic stainless, the wall spring design of the present invention enables a use of a larger variety of lower strength material. Our design also enables thinner materials to be used to lower stress at a weak point.
In FIG. 6, an ammunition case 600 includes deformation of a case wall 602 made in a pattern 604 of deformations (i.e., dimples of varying geometries) directed inwardly. This design enables a balance of outer profile maintenance for general loading and handling while giving spring characteristics of the structure in an axial direction. During firing, internal pressure forces the case wall 602 against a supporting barrel and the tube is stretched in an axial direction allowing a bottom 606 of the case wall 602 to be supported by the bottom 606.
In FIG. 7, an ammunition case 700 includes deformation of a case wall 702 made in a pattern 704 of deformations (i.e., single row of dimples) directed inwardly.
Other embodiments may be included. For example, in one embodiment, an aluminum alloy base is replaced by a base of higher modulus of elasticity. The higher modulus material will not deform as much under a firing pressure and this prevent a tube from deforming to a limit of failure. Other material can include stainless steel and other iron alloys having both low cost and easy manufacturing. While an iron alloy base may weigh more than an aluminum alloy base and detracts from an overall weight reduction goal, a final assembly will still weigh less than existing brass ammunition cases. In higher length to diameter ratio designs like rifle casing, the effect of base weight is diminished.
In another embodiment, a typical ammunition case material is reduced up to 50% in thickness. In this design for current gun barrels designed to accept bullets and cartridges of defined dimensions, it is still necessary for an open end (bullet end) of the case to maintain both barrel fit on the outside diameter and bullet fit and retention on an inside diameter. To accomplish this, a compression ring is added to a neck of the tube such that the effective thickness of the assembled neck is returned to the design standard.
In still another embodiment, a casing can be designed to optimum weigh performance and simplicity of manufacture by requiring a new gun barrel breach configuration that accepts a reduced thickness casing. Here the casing, reduced up to 50% in thickness, does not need an additional compression collar on a neck.
In certain applications, it is desirable to have an ammunition casing that cannot be easily reused. A geometry of deformation can be created such that a deformation under firing is plastic and the casing does not return to its original shape, making the case more difficult or impossible to reload.
It would be appreciated by those skilled in the art that various changes and modifications can be made to the illustrated embodiments without departing from the spirit of the present invention. All such modifications and changes are intended to be within the scope of the present invention except as limited by the scope of the appended claims.

Claims

What is claimed is:

1. An ammunition case comprising:

an elongate interior cavity for receiving a propellant and a projectile and extending along a longitudinal axis between a top end and a bottom end; and

a bottom corner of the cavity having a reversed radius design supported by a shaped base.

2. The ammunition case of claim 1 wherein a casing encloses the elongate interior cavity, an exterior of the casing deformed in a lower area during manufacturing to exhibit a spring wall section.

3. The ammunition case of claim 1 wherein a casing encloses the elongate interior cavity, an exterior of the casing having a pattern of deformations directed inwardly.

4. The ammunition case of claim 3 wherein the pattern of deformations are dimples of varying geometries.

5. The ammunition case of claim 3 wherein the pattern of deformations are a single row of dimples.

6. An ammunition case comprising:

a bottom corner of the cavity having a broad radius design supported by a shaped base.

7. The ammunition case of claim 6 wherein a casing encloses the elongate interior cavity, an exterior of the casing deformed in a lower area during manufacturing to exhibit a spring wall section.

8. The ammunition case of claim 6 wherein a casing encloses the elongate interior cavity, an exterior of the casing having a pattern of deformations directed inwardly.

9. The ammunition case of claim 8 wherein the pattern of deformations are dimples of varying geometries.

10. The ammunition case of claim 8 wherein the pattern of deformations are a single row of dimples.

11. The ammunition case of claim 8 wherein the pattern of deformations are one or more circumferential rings.

12. An ammunition case comprising:

a bottom corner of the cavity having an angle/radius combination supported by a shaped base.

13. An ammunition case comprises:

a case, the case having a wall deformed in a pattern of deformations directed inwardly, enabling a balance of outer profile maintenance for general loading and handling while giving spring characteristics of in an axial direction.

14. The ammunition case of claim 13 wherein the pattern of deformations comprises grooves or dimples of varying geometries.

15. An ammunition case comprising:

having one or more grooves rolled into the sidewall above a bottom corner.