Patent Application
20230051965
The present invention relates to optimizing ammunition casing formation and more particularly, the present invention relates to methods for forming consistently high precision dimensional tolerance casing assemblies created for longevity in high reuse situations.
Precision in ammunition dimensions is of paramount importance to ensure safe operation when discharging rounds. If precision is not observed, the round can be difficult, if not impossible, to feed into the firing chamber from an ammunition magazine and may also become jammed when casing ejection is required. Further still, “stovepiping” can occur when the casing becomes lodged partway from the ejector port.
Enthusiasts generally collect the casings from discharged ammunition in order to have the casing recharged and the ammunition refurbished for further use of the casings. This is a cost saving measure but can compromise the dimensional characteristics of the casing base and/or casing in light of the extreme pressures and temperatures attributed to detonation and release of the projectile. After repeated use, the base of the casing may be fatigued or have irregularities with respect to performance.
Generally, casing cylinders and/or casing bases are made of low carbon steel, aluminum or castings. The widely used technique to produce a high tolerance diameter casing is by employing a screw machine (a computer numerical control, CNC,) process.
The casings and bases are usually manufactured in very high production run amounts, typically ranging in the millions of pieces. As the tooling wears, the dimensional consistency can be affected. One such inconsistency can be seen in concentricity of the casing itself and dimensional variation in the diameter of the bases.
In the prior art, there are a number of documents proposing solutions to the known problems in reuse of spent ammunition components.
As an example, Viggiano, in U.S. Pat. No. 10,260,847, issued Apr. 16, 2019, teaches:
Further elaboration is made with respect to the steel in the Viggiano disclosure:
Although a very useful disclosure, there is no specific discussion as to the use of the 400 series steel for the bases, but rather the discussion is directed to aluminum for this component. As an enhancement to this disclosure, a mirror finished base composed of, for example, series 400 stainless steel, would further enhance, not only the above-mentioned application, but also casings and bases therefor generally.
The disclosure also has teachings regarding the presence of a wave shaped projection forming a gap between the casing base and casing cylinder. The text teaches:
From the teachings of this passage, there is significant movement and deformation between the casing base and casing cylinder.
Nuetzman et al., in U.S. Pat. No. 9,157,709, issued Oct. 13, 2015, discloses a multiple step process for forming a casing cartridge. The disclosure does not delve into mitigation of dimensional variation of the product under high volume production runs.
Burrow, in U.S. Pat. No. 10,612,896, issued Apr. 7, 2020, discloses a method for manufacturing a metal injection molded ammunition cartridge. A stainless steel composition is taught for the casing, however, there is no instruction regarding dimension control during manufacturing or mirror finishing the stainless steel base of the casing.
Kramer Industries online, kramerindustriesonline.com, teaches polishing techniques for returning brass casings to pre-fired shine by using a vibratory bowl machine with walnut shell grit and/or corn cob grit. Although useful, it would be more desirable to impart a finish to the casing during manufacturing that inherently resists accretion of debris, staining, etc.
Midvale Industries Inc., midvaleindustries.com, provides ammunition finishing techniques for new or used casings. These include batch vibratory finishing, continuous vibratory finishing, batch centrifugal finishing and rotary drum washing, as with the Kramer Industries method, these processes are post-manufacturing operations as opposed to preventative treatment measures during manufacturing runs of the casing bases.
In light of the necessity for dimension accuracy and surface cleanliness of ammunition casing bases intended for reuse, there still exists a need for methodology to ensure these attributes as well as mechanical integrity for repeated reuse of casing assemblies.
The present invention addresses such needs.
One object of the present invention is to provide an improved method of forming ammunition components.
Another object of one embodiment of the present invention is to provide an ammunition casing assembly, comprising:
The cooperating engagement members may be either of recesses or projections configured for keyed registration with one another to prevent any relative rotation in use or otherwise. This also provides for the possibility of increasing the amount of propellant, etc. that may be incorporated in the casing cylinder where projections are utilized as the cooperating engagement members.
It has been found that the keyed mechanical consolidation between the casing base and cylinder improves longevity of the casing for reuse, reduces thermal damage over repeated use and permits the use of different metal materials which, in turn, reduces the mass of the casing base and cylinder. The latter is particularly advantageous where military personnel can reduce the mass of material carried in service.
In respect of the cooperating engagement members, any suitable configurations may be employed that can be configured using known machining and metal forming techniques. To this end the recesses may be arced, circular, polygonal, star shaped, etc.
Positioning and configuration geometry of the cooperating engagement members may be radially spaced apart equidistantly with a common radius from the centre of the casing base and cylinder. Alternatively, where different metals are employed for the casing and cylinder, different disposition of the members may be necessary to compensate for different thermal characteristics of the chosen materials. This is also believed to compensate for warping or other dimensional variations which may be ephemeral or lasting.
In respect of the metal, a desirable metal for the casing comprises 400 series martensitic stainless steel.
Treatment comprises a live tooling operation in, for example, a computer numerical control (CNC) overall operation. Other operations will be appreciated by those skilled.
The grinding step imparts a reflective surface to the base which may also be coated using known techniques such as vapour deposition to enhance strength and retard oxidation and debris build-up. Further, the coating may be a strengthening composition, a colour composition, an identification coating, a tracking coating and combinations thereof.
The grinding/polishing may be conducted in concert with a cooling operation using liquid or gas coolant.
Although series 400 stainless steel is most desirable for the casings and bases, other conventional metals or amalgams may be utilized such as brass, aluminum, titanium, inter alia. Suitable selections will be appreciated by those skilled in the art.
Although the use of the 400 series steel for the base provides for simplified recovery of spent casings magnetically, the bases may also incorporate a colour composition, an identification coating, a tracking coating and combinations thereof depending on the intended use.
The grinding step is achieved using a diamond wheel to impart a mirror reflective finish to the casing base. With such a finish there is a reduction in the amount of debris that is attracted to the base post firing and the casing base has a lower coefficient of friction. Further, magazine loading is simplified as is transport therefrom to the firing chamber and subsequent ejection of the spent casing post firing.
Depending on the specific situation, the grinding/polishing may be conducted continuously or discontinuously or in a predetermined sequence of either or both.
To further enhance the strength and surface durability of the casing base, the same may be treated with an additional material to alleviate deflagration damage, surface damage and general durability. Suitable treatment procedures and compositions will be appreciated by those skilled in the art. Examples include vapour deposition of titanium, graphene, chromium, nickel, etc.
The casing and base comprise two pieces, a casing base and casing cylinder or a one-piece structure integrating both.
As a further object of one embodiment of the present invention, there is provided a method of forming a casing for a firearm ammunition, comprising:
As an option, the method may include further including the step of mechanically connecting the base and the casing with a secondary mechanical connection.
In accordance with yet another object of one embodiment of the present invention is to provide a method for forming an ammunition casing, comprising:
The grinding step can be applied to single piece casings (casing and base integrated) or those having more than one piece, i.e. a casing and base connected.
Advantageously, the grinding operation may be applied to pre-existing casings with bases to impart a diamond ground mirror finish to the casing.
The grinding technology discussed herein is also useful to grind oversize or otherwise larger diameter bases which may be diamond ground to a predetermined diameter depending on the requirements for the end user or ballistic specifications.
Conveniently, with the grinding step imparted by a diamond wheel, for example, the coefficient of friction of the base is commensurately lowered. This manifests in smooth loading and ejection action, retards oxidation build-up and ensures diameter precision over repeated use.
The method may further include:
The method may be conducted in a continuous line operation, a continuous rotational operation or any combination thereof.
Having thus generally described the invention, reference will now be made to the accompanying drawings, illustrating preferred embodiments.
Similar numerals used in the Figures denote similar elements.
Referring initially to
In a first embodiment, bar stock material 12, which may be selected from, for example, series 400 stainless steel, is introduced for profiling with a diamond wheel 14. Wheel 14 has a predetermined profile to impart the same profile with a specific predetermined tolerance to bar stock 12.
The predrilled casing base 18 is then moved to cell 2, referenced as 22, for a secondary drilling operation. For clarity, the movement of the base 18 may be linearly through the stages of
Subsequent to the secondary drilling in cell 2, the base 18 is advanced to cell 3, denoted by numeral 24 for a pre-finishing reaming operation. The next stage, cell 4, (26), exposes the base 18 to a spot face operation and then subsequently to a finishing reaming operation 28 in cell 5. Spot face finishing is completed in cell 6, denoted by numeral 30.
A supply of casing cylinders 32 may be supplied from, for example, a vibratory bowl feeder 34. As is well known in the ammunition art, the casing cylinder 32, receives propellant and a projectile (neither shown).
The casing cylinders 32 positioned from the bowl feeder 34 are then coupled to a respective casing base 18 by well-known methods, an example of which is compression fit. This is broadly referenced at cell 7, denoted by numeral 36. The next steps typically associated with the formation of the based casing include a restrike operation at cell 8, swage end operation at cell 9 and a restrike operation of the swage end at cell 10, represented by numerals 38, 40 and 42, respectively.
Once completed the based casings (not shown) are conveyed at 44 for secondary operations such as washing, inspection/quality control and packaging all of which are represented by numeral 46.
In alternate embodiments, the casing and base can be a single piece item made with the bar stock in reference to
Further, in some instances, it may be desirable to have the casing diamond polished as well as the base. In this alternative, the profile of the diamond wheel would conform to the profile of the casing.
As mentioned herein, the overall process can be done in any number of ways known to those skilled. For example, multiple bases can be treated by a rotational mandrel and the individual operations conducted in a linear or rotational manner.
In a further embodiment of the technology set forth herein,
In the example, the first cooperating engagement members 50 are depicted as a plurality of arcuate recesses. The recesses are equidistantly spaced apart and concentric with the vertical axis 54 of the casing base 18 all with an equal distance from the axis 54. The members 50 are spaced inwardly from the perimeter 56 of the casing base 18 and recessed from the top edge 58 of the casing base. In this manner, a seating is generally formed having a wall 60 surrounding the members 50.
Referring now to
The formation of members 50 and 52 in casing base 18 and casing cylinder 32 may be introduced at a suitable stage in the processing operations delineated in
As has been generally stated herein previously, the type of metals used for the base casing 18 and the casing cylinder 32 may be the same or different. This will depend upon the specific user requirements for the ammunition.
Turning to
| Number | Date | Country | |
|---|---|---|---|
| 63195730 | Jun 2021 | US |
