WO2023105381A1

WO2023105381A1 - Method for manufacturing cases of cartridges for smoothbore shotguns and case of cartridge for smoothbore shotguns

Info

Publication number: WO2023105381A1
Application number: PCT/IB2022/061758
Authority: WO
Inventors: Giorgio Pizzamiglio
Original assignee: Giorgio Pizzamiglio
Priority date: 2021-12-09
Filing date: 2022-12-05
Publication date: 2023-06-15

Abstract

A method for manufacturing cases (1) of cartridges for smoothbore shotguns, characterized in that it comprises: - a step of providing a pellet made of metallic material; - a step of cold-forming the pellet made of metallic material in order to provide a case (1) which has a bottom wall (2) and a cylindrical side wall (3), the cylindrical side wall (3) having a taper from the bottom wall (2) to the opposite end, so as to obtain a frustum shape structure of the external surface (3a) of the cylindrical side wall (3); - a step of providing, during the cold-forming step, a hole (4) at the bottom wall (2), the hole (4) being designed to accommodate a cartridge primer.

Description

METHOD FOR MANUFACTURING CASES OF CARTRIDGES FOR SMOOTHBORE SHOTGUNS AND CASE OF CARTRIDGE FOR SMOOTHBORE SHOTGUNS

The present invention relates to a method for manufacturing cases of cartridges for smoothbore shotguns and a case of cartridge for smoothbore shotguns.

Cartridges for smoothbore shotguns are constituted by a so-called case, which is provided with an end plate, and which supports the primer capsule, inside which are placed the firing charge, the wad, and the pellets.

The end plate is made of metal, for example in brass-plated sheet iron, while the side wall of the case, also called the hull or casing, is made of plastic.

The mutual locking together of the end plate with the hull is done using a so-called base wad, also made of plastic.

The known solutions, although widely used, are not however devoid of drawbacks.

In fact, both the hull and the base wad are made of plastic and, as a consequence, are extremely pollutant if they are abandoned in the environment.

Furthermore, even if they are picked up, it is particularly laborious to recycle or recover the cases, it being necessary to separate the three components, each one of which is, moreover, made of different materials.

Finally, it should be noted that the manufacturing process is not at all simple, since three elements need to be produced separately and then coupled together.

The aim of the present invention is to provide a method for manufacturing cases of cartridges for smoothbore shotguns, as well as a case of cartridge for smoothbore shotguns, that is capable of improving the known art and ballistic efficacy in one or more of the above mentioned aspects. Within this aim, an object of the invention is to make available a method for manufacturing cases of cartridges for smoothbore shotguns and a case of cartridge for smoothbore shotguns that makes it possible to obtain a case that is completely recyclable.

Another object of the invention is to provide a method for manufacturing cases of cartridges for smoothbore shotguns, and a case of cartridge for smoothbore shotguns, that is highly reliable, easy to implement and of low cost.

This aim and these and other objects which will become better apparent hereinafter are achieved by a method for manufacturing cases of cartridges for smoothbore shotguns and by a case of cartridge for smoothbore shotguns according to the independent claim, optionally provided with one or more of the characteristics of the dependent claims.

Further characteristics and advantages of the invention will become better apparent from the detailed description that follows of a preferred, but not exclusive, embodiment of the method for manufacturing cases of cartridges for smoothbore shotguns according to the invention, which is illustrated for the purposes of non-limiting example in the accompanying drawings wherein:

Figure 1 is a side view of the case according to the invention;

Figure 2 is a cross-sectional view of the case taken along the plane of arrangement identified by the line II-II of Figure 1;

Figure 3 is a perspective longitudinal cross-sectional view of the case according to the invention.

With reference to the figures, the method for manufacturing cases of cartridges for smoothbore shotguns according to the invention comprises the following steps:

- a step of providing a pellet made of metallic material;

- a step of cold-forming the pellet made of metallic material in order to provide a case 1 which has a bottom wall 2 and a cylindrical side wall 3, the cylindrical side wall 3 having a taper from the bottom wall 2 to the opposite end, so as to obtain a frustum shape structure of the external surface 3 a of the cylindrical side wall 3;

- a step of providing, during the cold-forming step, a hole 4 at the bottom wall 2, the hole 4 being designed to accommodate a cartridge primer.

Preferably, the step of cold-forming comprises a sequence of intermediate steps of cold plastic deformation of the pellet of metallic material.

Advantageously, the thickness of the cylindrical side wall is progressively thinner proceeding from the bottom wall 2 to the opposite end.

Conveniently, the step of providing a hole 4 has a step of providing at least one cylindrical portion 4a which extends around the axis 100 of the cylindrical side wall 3.

In particular, the cylindrical portion 4a is open at its longitudinal ends.

Preferably, the pellet made of metallic material comprises an aluminum pellet.

However, there is no reason why the metallic material cannot be selected from the group comprising:

- steel;

- copper;

- brass.

The present invention further relates to a case 1 which has a bottom wall 2 and a cylindrical side wall 3.

The cylindrical side wall 3 has, in particular, a taper from the bottom wall to the opposite end, so as to obtain a frustum shape structure of the external surface 3 a of the cylindrical side wall 3, as clearly shown in the figures.

The case 1 is made entirely of metallic material.

In particular, the case 1 is made using the method described above.

In practice it has been found that the invention fully achieves the intended aim and objects by providing a case that is completely recyclable and constituted by a single metallic material.

Furthermore, since the taper of the side wall 3 has been provided, it made it possible to obtain two advantages.

Firstly, obtaining the frustum shape structure of the external surface 3a has made it possible to reduce plastic deformation in the radial direction of the side wall following the discharge, thus enabling the exit of the case from the chamber.

Furthermore, this shape has made it possible to progressively reduce the thickness of the side wall 3 starting from the bottom wall 2, thus making possible an appreciable reduction in the weight and in the overall cost, and therefore making the solution, with reference in particular to the use of aluminum as the metal, extremely competitive from an economic viewpoint as well.

The invention also is considerably advantageous in terms of ballistics.

In fact, owing to the effect of the new case the following advantages are obtained:

- less deformation of the sphericity of the pellets, with consequent better penetration of air and therefore greater kinetic force and greater reachable distance;

- the spread pattern of pellets: in a traditional cartridge, the spread pattern is characterized by an elongated pear shape (which is why a spread pattern size of up to 2.5/3 meters in length can be observed, with the consequence that it reaches the target with different speeds, and therefore different penetrations, between the first pellets and the last); in the new invention the spread pattern is characterized by a frustum shape and a maximum size of 1 meter, with identical speed and penetration of the pellets.

These superior characteristics will be decisive in the coming years when, compulsorily, lead pellets will be replaced by steel pellets with lower mass.

The invention, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements.

In practice the materials employed, as long as they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.

The disclosures in Italian Patent Application No. 102021000030914 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

6 CLAIMS

1. A method for manufacturing cases (1) of cartridges for smoothbore shotguns, characterized in that it comprises the steps that consist in:

- providing a pellet made of metallic material;

- cold-forming said pellet made of metallic material in order to provide a case (1) which has a bottom wall (2) and a cylindrical side wall (3), said cylindrical side wall (3) having a taper from the bottom wall (2) to the opposite end, so as to obtain a frustum shape structure of the external surface (3a) of said cylindrical side wall (3);

- providing, during said cold-forming step, a hole (4) at said bottom wall (2), said hole (4) being designed to accommodate a cartridge primer.

2. The method according to claim 1, characterized in that said coldforming step comprises a sequence of intermediate steps of cold plastic deformation of said pellet of metallic material.

3. The method according to one or more of the preceding claims, characterized in that the thickness of said cylindrical side wall (3) decreases progressively from said bottom wall (2) to the opposite end.

4. The method according to one or more of the preceding claims, characterized in that said step of providing a hole (4) has a step of providing at least one cylindrical portion (4a) which extends around the axis (100) of said cylindrical side wall (3).

5. The method according to one or more of the preceding claims, characterized in that said pellet made of metallic material comprises an aluminum pellet.

6. The method according to one or more of the preceding claims, characterized in that said metallic material is chosen from the group comprising:

- steel;

- copper;

- brass. 7

7. A case (1) of cartridges for smoothbore shotguns, characterized in that it comprises a bottom wall (2) and a cylindrical side wall (3), said cylindrical side wall (3) having a taper from said bottom wall (2) to the opposite end so as to obtain a frustum shape structure of the external surface (3a) of said cylindrical side wall (3), a hole (4) being defined at said bottom wall (2), said hole (4) being designed to accommodate a cartridge primer.

8. The case (1) according to claim 7, characterized in that the thickness of said cylindrical side wall (3) decreases progressively from said bottom wall (2) to the opposite end.

9. The case (1) according to one or more of claims 7 to 8, characterized in that said hole (4) has a cylindrical portion (4a) which extends around the axis (100) of said cylindrical side wall (3).

10. The case (1) according to one or more of claims 7 to 9, characterized in that said case (1) is made of aluminum.