AMMUNITION SEALANT FLOW FEATURES

Abstract

A polymer ammunition cartridge that includes a cartridge body extending from the base end and a cartridge nose extending from the body is disclosed. The cartridge nose has a shoulder and a neck that extends to a projectile opening forming a distal end of the cartridge. Defined on the inner surface of the neck at an intermediate position between the shoulder and the projectile opening is an annular shelf. The neck further includes at least one wicking groove formed on the inner surface and extending from the projectile opening to the annular shelf. The wicking groove is configured to receive adhesive after a bullet has been installed into the neck and the annular shelf arrests the flow of adhesive thereby structurally limiting bondage between the neck and a bullet to the longitudinal length of the wicking grooves.

Claims

1. A polymer ammunition cartridge having a base end and a cartridge body extending from the base end and a cartridge nose extending from the cartridge body, the cartridge nose comprising: a shoulder and a neck, the neck extending to a projectile opening at a distal end of the cartridge; an annular shelf defined at an intermediate location between the projectile opening and the shoulder; and at least one wicking groove defined on an inner surface of the neck and extending from the projectile opening to the annular shelf.

2. The cartridge of claim 1, further comprising a plurality of wicking grooves defined on the inner surface of the neck.

3. The cartridge of claim 2, wherein the plurality of wicking grooves are substantially radially symmetrically disposed about the inner diameter of the neck.

4. The cartridge of claim 2, wherein at least one of the plurality of wicking grooves defines a longitudinal axis that is parallel to a longitudinal axis of the cartridge.

5. The cartridge of claim 2, wherein each wicking groove has a length substantially equal to each other wicking groove.

6. The cartridge of claim 2, further comprising an annular groove defined about the inner surface of the neck.

7. The cartridge of claim 6, wherein the annular groove is formed between the projectile opening and the annular shelf.

8. The cartridge of claim 7, wherein the at least one wicking groove connects to the annular groove.

9. The cartridge of claim 7, wherein the annular groove integrally connects with each of the wicking grooves.

10. The cartridge of claim 2, wherein at least two of the wicking grooves have different maximum lengths.

11. The cartridge of claim 1, wherein the at least one wicking groove is configured to receive an adhesive after a bullet has been installed in the cartridge.

12. The cartridge of claim 11, wherein the at least one wicking groove and the adhesive are configured to generate a bullet pull value of at least 60 pounds of force.

13. The cartridge of claim 1, wherein the neck between the shoulder and the annular shelf has a uniform inner diameter.

14. The cartridge of claim 1, wherein the neck between annular shelf and the shoulder is configured to cause diametric interference with a bullet installed in the cartridge.

15. The cartridge of claim 1, wherein the annular shelf is configured to arrest flow of an adhesive introduced through the at least one wicking groove.

16. The cartridge of claim 1, wherein the at least one wicking groove comprises a spiral groove.

17. A nose for a polymer ammunition cartridge, the nose comprising: a shoulder having a shoulder coupling joint and a neck opposite the shoulder coupling joint, the neck defining a length terminating in a projectile opening; an annular shelf formed along the length of the neck between the projectile opening and the shoulder; and a plurality of wicking grooves defined on an inner surface of the neck and terminating at the annular shelf, the wicking grooves configured as an adhesive flow path from the projectile opening to the annular shelf.

18. The nose of claim 17, wherein the plurality of wicking grooves extend from the projectile opening to the annular shelf.

19. The nose of claim 18, wherein the plurality of wicking grooves are parallel to a longitudinal axis of the nose.

20. The nose of claim 17, further comprising a uniform inner neck diameter defined between the annular shelf and the shoulder that is less than an inner neck diameter defined between the projectile opening and the annular shelf.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. Component parts shown in the drawings are not necessarily to scale, and may be exaggerated to better illustrate the important features of the invention. Dimensions shown are exemplary only. In the drawings, like reference numerals may designate like parts throughout the different views, wherein:

[0015] FIG. 1 is a side view of a partial case failure of the cartridge neck, known to occur in the prior art.

[0016] FIG. 2 is a side perspective view of a partial case failure of the cartridge body, known to occur in the prior art.

[0017] FIG. 3 is a cross-sectional perspective view of a polymer cartridge according to one embodiment of the invention.

[0018] FIG. 4 is a cross-sectional side view of the embodiment of the polymer cartridge of FIG. 2.

[0019] FIG. 5 is a partially transparent cross-sectional perspective view of an embodiment of a cartridge nose according to the invention.

[0020] FIG. 6 is a magnified view of the neck portion of the cartridge nose of FIG. 5.

[0021] FIG. 7 is a perspective cross-sectional view of an embodiment of the cartridge nose of FIG. 5 with a partially transparent bullet installed therein.

[0022] FIG. 8 is a perspective cross-sectional view of an alternate embodiment of the cartridge nose.

[0023] FIG. 9 is a perspective cross-sectional view of an additional alternative embodiment of a cartridge nose.

[0024] FIG. 10 is a perspective cross-sectional view of an additional alternative embodiment of a cartridge nose.

[0025] FIG. 11 is a perspective cross-sectional view of an additional alternative embodiment of a cartridge nose.

DETAILED DESCRIPTION OF THE INVENTION

[0026] The following disclosure presents exemplary embodiments of a polymer ammunition cartridge which has improved characteristics of reliability and increased resistance to partial or complete case tearing. The disclosed polymer cartridge has an engineered cartridge nose that consistently creates the desired bullet pull value. Thus, the disclosed polymer cartridge achieves a similar level of reliability and consistency in performance as metallic equivalents without the downside of being heavy, expensive and potentially toxic.

[0027] Throughout the disclosure, certain terms may be used to more easily and clearly define the claimed invention. These terms are not meant to be limiting but merely for the purpose of describing the invention in a clear and concise manner. Thus, as used herein, proximal and/or distal may be used to describe the general orientation of a cartridge when it is loaded into a firearm chamber. Thus, the skilled artisan will readily understand that a distal end would refer to the bullet receiving end, e.g., the projectile opening 32, of a cartridge and a proximal end refers to the primer receiving end, e.g., the base end 16, of the cartridge.

[0028] FIG. 3 is a cross-sectional perspective view of one embodiment of a polymer cartridge 10 according to the present invention. The polymer cartridge 10 has a cartridge body 12 molded over a primer insert 14, which defines the proximal or base end 16 of the cartridge. The primer insert 14 has a primer recess 18 configured to frictionally fit a primer therein, as is known for ammunition. The primer recess 18 is in fluid communication with the propellant chamber 22 via a flash hole 20 defined through the primer insert 14. The cartridge body 12 extends into a cartridge nose 24, which includes the shoulder 26 and the neck 30 of the cartridge.

[0029] FIG. 4 is a cross-sectional side view of the polymer ammunition cartridge 10. In some embodiments, the cartridge nose 24 connects to the cartridge body 12 at a shoulder joint 28 defined at the lower end of the cartridge nose. These embodiments are considered a three-piece cartridge, which includes the primer insert 14, the cartridge body 12 and the cartridge nose 24 as distinct pieces secured together during an assembly process. The cartridge nose 24 and the cartridge body 12 can be secured together at the shoulder joint 28 by directly molding the cartridge nose onto the cartridge body or using an adhesive applied at the shoulder joint during the assembly process. Alternatively, any other conventional means for securing two molded polymer pieces together may be used, e.g., welding, bonding using a solvent, spin-welding, vibration-welding, ultrasonic-welding, or laser-welding techniques that are known in the art. Alternatively, the cartridge body 12 and the cartridge nose 24 can be molded as a single piece, in which case the cartridge 10 is a two-piece cartridge including the primer insert 14 and an integrally formed cartridge body 12 transitioning into the cartridge nose 24.

[0030] The neck 30 of the polymer cartridge 10 extends into a projectile opening 32 defined at the distal end of the neck. The projectile opening 32 is configured to receive a projectile, e.g., a bullet, during the assembly process of the polymer cartridge 10. Formed on the inner surface of the neck 30 is an annular shelf 34. The annular shelf 34 is formed at an intermediate location between the projectile opening 32 and the shoulder 26 to provide a physical barrier for limiting flow of an adhesive applied to the inner surface of the neck 30. At least one wicking groove 36 is also formed on the inner surface of the neck 30 and extends from the projectile opening 32 to the annular shelf 34. Preferably, there is a plurality of wicking grooves 36 formed about the inner surface of the neck 30. The wicking grooves 36 terminate at the annular shelf 34 to define a flow path for an adhesive that is applied at the projectile opening 32 after a bullet has been installed into the polymer cartridge 10. The annular shelf 34 is designed to stop the flow of adhesive at the shelf, thereby limiting the bonded area to the length of the wicking grooves 36. The combination of the annular shelf 34 and one or more wicking grooves 36 focuses the bonded area between a bullet and the neck 30 of the cartridge 10 to significantly reduce the occurrence of cartridge failures or the unwanted dislodgment of the bullet from its seated depth. Further, the combination of features allows a manufacturer to readily and reliably select the desired bullet pull value by controlling the placement of the annular shelf 34 to thereby control the amount of bonded area between the bullet and the one or more wicking grooves 36.

[0031] FIG. 5 is a partially transparent cross-sectional view of one embodiment of the cartridge nose 24. A longitudinal axis LA is defined through the center of the cartridge nose 24 and extends through the polymer cartridge 10. In some embodiments, at least one wicking groove 36 is parallel with the longitudinal axis LA of the polymer cartridge 10. In preferred embodiments, each of the plurality of wicking grooves 36 are parallel with the longitudinal axis LA of the polymer cartridge 10 and are substantially radially symmetrical about the inner surface of the neck 30. Making the wicking grooves 36 parallel to and radially symmetrical about the longitudinal axis of the cartridge 10 ensures a smooth and even release of a projectile upon firing.

[0032] FIG. 6 is a magnified view of the neck 30 portion of a cartridge nose 24 according to the present invention. In some embodiments, the inner diameter of the neck 30 between the projectile opening 32 and the annular shelf 34 is greater than the inner diameter of the neck 30 between the annular shelf 34 and the shoulder 26. Preferably, the inner diameter between the shoulder 26 and the annular shelf 34 is uniform whereas the inner diameter of the neck 30 between the projectile opening 32 and the annular shelf 34 is non-uniform. The difference in the internal diameter above and below the annular shelf 34 in the cartridge nose 24 is small and tightly controlled to ensure mechanical engagement with a projectile can still be achieved throughout the length of the neck 30, e.g., difference can be about 0.001 inches. The inner diameter of the neck 30 between the shoulder 26 and the annular shelf 34 is configured to cause frictional engagement with a bullet 38 that has been installed in the polymer cartridge. The frictional engagement between the neck 30 below the annular shelf 34 and a bullet installed therein further contributes to the generation of a consistent bullet pull value resulting in reliable bullet discharge upon firing of the cartridge 10.

[0033] FIG. 7 is a cross-sectional view of an embodiment of the cartridge nose 24 that has a partially transparent bullet 38 installed therein. The bullet 38 is of conventional style, having a base 40 that extends internally beyond the length of the neck 30 and into the shoulder region. The neck 30 between the annular shelf 34 and the shoulder 26 mechanically engages with the body 42 of the bullet due to the diametral interference generated between the inner surface of the neck 30 and outer surface of the body 42 of the bullet 38. The wicking grooves 36 provide the flow path for an adhesive applied at the projectile opening 32 to bond a portion of the bullet 38 with the neck 30. The annular shelf 34 stops the adhesive from flowing beyond the proximal end of the wicking grooves 36, thereby limiting the bonded area to the wicking grooves 36. Using a conventional ammunition adhesive applied to the wicking grooves 36, a bullet pull value of 50-200 pounds of force can be generated. Changing the type of adhesive used, selected from among the various known ammunition adhesives, and controlling the number and the dimensions of the wicking grooves 36 can produce the desired bullet pull value of about 60-pounds of force consistently. In some preferred embodiments, an acrylic-based adhesive is applied to the wicking grooves 36 after the bullet 38 has been installed in the polymer cartridge 10, which can consistently produce at least a 60-pound bullet pull value.

[0034] Thus, by controlling the bonded surface area between the neck 30 and the bullet 38 and introducing the annular shelf 34 to stop the flow of adhesive, the problem of too high of bondage between the bullet and the cartridge has been alleviated. This has resulted in a significant increase in the reliability of the polymer cartridge 10 by reducing the frequency of partial and complete case tearing during live-fire events. Further, by controlling the number and dimensions of the wicking grooves 36, the problem of too low a bullet pull value is avoided and the polymer cartridge 10 can be consistently produced with the desired bullet pull value.

[0035] FIG. 8 is a cross-sectional perspective view of an alternate embodiment of a cartridge nose 44. Cartridge nose 44 includes a plurality of wicking grooves 36 and further includes at least one annular groove 46. The annular groove 46 is defined at an intermediate location in the inner surface of the neck 30 between the projectile opening 32 and the annular shelf 34. In preferred embodiments, the annular groove 46 is defined at the proximal end of the wicking grooves 36 immediately adjacent to the annular shelf 34.

[0036] At least one of the wicking grooves 36 is integrally connected to the annular groove 46 to define a common flow path for adhesive to flow from the projectile opening down the wicking grooves into the annular groove. Preferably, each of the wicking grooves 36 connects with the annular groove 46 to form a flow path from each wicking groove to the annular groove. The wicking grooves 36 and the annular groove 46 can combine to provide an area of bondage with the bullet that circumvolves the outer diameter of the bullet at the annular groove 46 and extends longitudinally along the outer diameter of the bullet corresponding to the length of each wicking groove 36. Regardless of the embodiment, after the bullet has been installed in the polymer cartridge 10, the annular shelf 34 provides a structural blockage of the adhesive thereat and mechanical engagement with the bullet 38 there below by causing diametric interference between the bullet 38 and the remainder of the neck 30 to the shoulder 26.

[0037] The total number of wicking grooves 36 and the specific dimensions for each individual wicking groove 36, i.e., length, depth and width, can vary depending on the manufacturer's specific need. For instance, FIG. 9 is a cross-sectional perspective view of an embodiment of a cartridge nose 56 that has a plurality of wide wicking grooves 48. The wide wicking grooves 48 can include an angled sidewall 50 that angles inwards from the inner surface of the neck 30 into the groove. Alternatively, the wide wicking grooves 48 can have straight or curved sidewalls similar to those illustrated in the wicking grooves 36. The wide wicking grooves 48 can be used to decrease the total adhesive surface area in the cartridge neck 30 by increasing the dimensions of the individual grooves to thereby reduce the overall number of grooves. For instance, a cartridge nose 56 with a plurality of evenly spaced apart wide wicking grooves 48 may have a total bondage surface area of 37.8 mm.sup.2 whereas a cartridge nose 30 with a plurality of evenly spaced apart wicking grooves 36 may have a total bondage surface area of 106.5 mm.sup.2.

[0038] FIG. 10 is a cross-sectional perspective view of an alternate embodiment of a cartridge nose 54. The cartridge nose 54 has a combination of wicking grooves 36 and short wicking grooves 52. The short wicking grooves 52 have a longitudinal length that is less than the longitudinal length of the wicking grooves 36. The cartridge nose 54 can include an extended annular shelf 62 formed at a proximal end of the short wicking groove 52. The extended annular shelf 62 is configured to stop adhesive from flowing beyond the proximal end of the short wicking groove 52. Further, the extended annular shelf 62 increases the surface area with which the diametric interference between the bullet 38 and inner surface of the neck 30 is achieved. The combination of wicking grooves 36, 52 can be used to further control the total surface area in the cartridge neck 30 with which the bullet 38 will bond. Further embodiments can use a combination of the wide wicking grooves 48, short wicking grooves 52 and wicking grooves 36 to provide the desired surface area for adhesive bondage with the bullet to achieve the necessary bullet pull value.

[0039] FIG. 11 is a cross-sectional perspective view of a further alternative embodiment of a cartridge nose 58 having a spiral wicking groove 60. The spiral wicking groove 60 spirals about the inner surface of the neck 30 from the projectile opening 32 to the annular shelf 34. In some embodiments, there may be a plurality of spiral wicking grooves 60 that have different degrees of rotation about the inner surface of the neck 30.

[0040] Throughout this disclosure, the terms polymer and synthetic polymer and synthetic coating shall be interpreted in a non-limiting fashion and given a broad interpretation according to their plain and ordinary meaning. Polymer can mean a natural polymer or a synthetic polymer, and any invention described herein that refers to a synthetic polymer may, in an alternative embodiment, substitute a natural polymer for the synthetic polymer and vice versa. Examples of polymers as used herein include but are not limited to acrylic, polyethylene, polyolefin, polypropylene, polystyrene, polyvinylchloride, synthetic rubber, phenol formaldehyde, neoprene, nylon, polyacrylonitrile, PVB, silicone, and any of the foregoing in powdered, micronized powdered, or resin form.

[0041] The inventive concepts disclosed herein can be applied to virtually all ammunition cartridges of any caliber or size, including rifle and pistol ammunition cartridges as well as large caliber artillery rounds. Further, the disclosed inventive concepts apply equally to cartridges designed for military and civilian use.

[0042] Exemplary embodiments of the invention have been disclosed in an illustrative style. Accordingly, the terminology employed throughout should be read in a non-limiting manner. Although minor modifications to the teachings herein will occur to those well versed in the art, it shall be understood that what is intended to be circumscribed within the scope of the patent warranted hereon are all such embodiments that reasonably fall within the scope of the advancement to the art hereby contributed, and that that scope shall not be restricted, except in light of the appended claims and their equivalents.