Biodegradable wadding cup for a shotgun cartridge

Abstract

Disclosed is an intermediate part forming a wadding cup to be placed in the case of a cartridge for separating the explosive charge and the shot. It includes a cylindrical sleeve of outer diameter suitable for being inserted slidingly into the case, the sleeve having a front portion the end of which is open, suitable for containing the shot, and a rear portion including a cylindrical wad flush with the end of the rear portion, the intermediate part being formed of at least 95% by weight of biodegradable or decomposable materials, such as cardboard and cork. Also disclosed is a biodegradable cartridge with cup and wadding, complying with environmental rules.

Claims

1. An intermediate part for placement in a case (10) of a cartridge (200) to separate an explosive charge (20) from shot (30), said intermediate part comprising: a cylindrical sleeve (1) having an outside diameter adapted to being slidably inserted into the case (10) of the cartridge (200), said sleeve formed as a tube with a front portion (11) for containing said shot, an open end, and a rear portion (12) that contains a cylindrical wad (2) that closes off said rear portion completely, the cylindrical wad having a rear face (22) that is flush with an end of the rear portion (12) of the sleeve (1), at least 95% by weight of said intermediate part being constituted by biodegradable or decomposable materials.

2. The intermediate part according to claim 1, wherein at least 95% by weight of the sleeve (1) is formed by biodegradable materials.

3. The intermediate part according to claim 2, wherein the sleeve (1) is constituted by a cardboard tube of a thickness in a range of 0.4 mm to 1 mm.

4. The intermediate part according to claim 2, wherein at least 95% of the wad (2) is formed by biodegradable materials, by decomposable natural materials, or by a combination of both types of material.

5. The intermediate part according to claim 1, wherein the sleeve (1) is constituted by a cardboard tube of a thickness in a range of 0.4 mm to 1 mm.

6. The intermediate part according to claim 5, wherein at least 95% of the wad (2) is formed by biodegradable materials, by decomposable natural materials, or by a combination of both types of material.

7. The intermediate part according to claim 1, wherein at least 95% of the wad (2) is formed by biodegradable materials, by decomposable natural materials, or by a combination of both types of material.

8. The intermediate part according to claim 1, wherein the wad (2) comprises one or more materials chosen from the group consisting of: cork, cardboard, paper, wood fiber, and felt.

9. The intermediate part according to claim 8, wherein the wad (2) is formed in one piece of a single material, or it is formed of superposed slices of a same material or of different materials.

10. The intermediate part according to claim 8, wherein the wad (2) is formed of fragments of one or more materials that are amalgamated by a binder representing less than 1% of the total mass.

11. The intermediate part according to claim 1, wherein the wad (2) is held in place in the sleeve (1) by friction, or by friction and adhesive bonding.

12. The intermediate part according to claim 1, wherein the rear face (22) of the wad (2) is associated with a dish (3) made of a biodegradable material and having an end-wall (32) of diameter identical to the diameter of the sleeve (1) and a circular rim (31) that extends rearwards in alignment with said sleeve.

13. The intermediate part according to claim 12, wherein an assembly associating the dish (3) and the rear face (22) of the wad (2) comprises a rigid separator disk (4) having a periphery bearing against the end of the rear portion (12) of the sleeve (1).

14. The intermediate part according to claim 13, wherein the dish (3) and the separator disk are made of cardboard having a thickness ranging from 0.3 mm to 1 mm, and are fastened to the rear face (22) of the wad (2) by adhesive bonding.

15. The intermediate part according to claim 1, wherein the sleeve (1) is provided with slits (13) that are equidistant and that extend longitudinally from the front end (11) towards the rear portion (12) of said sleeve, said slits being cut fully or being in the form of partial pre-cuts.

16. The intermediate part according to claim 1, wherein at least 99% by weight of said intermediate part is constituted by biodegradable or decomposable materials.

17. The intermediate part according to claim 1, wherein the sleeve (1) has a length in a range of 35 mm to 45 mm, and the wad (2) has a length in a range of 3 mm to 20 mm.

18. The intermediate part according to claim 1, wherein the sleeve (1) has a length in a range of 35 mm to 45 mm, and the wad (2) has a length in a range of 3 mm to 20 mm.

19. A cartridge (200) for a gun having a smoothbore barrel, wherein said cartridge comprises a case (10) that is cylindrical in shape, the case having a rear portion mounted in a base (40) made of metal, an explosive charge (20) in contact with a primer (42), and a set of projectiles in the form of shot (30), said cartridge further comprising an intermediate part (100) according to claim 1 that separates the explosive charge (20) from the shot (30).

20. The cartridge according to claim 19, wherein said intermediate part (100) is made of materials suitable for being degraded or for decomposing at least to 95% by weight in the natural environment in less than 25 days.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention can be better understood and details of it appear in the light of the following description of a particular embodiment, given with reference to the accompanying figures, in which:

(2) FIG. 1 is a perspective view of an intermediate part of the invention;

(3) FIG. 2 is a section view of the same part.

(4) FIG. 3 is an exploded view of the various component elements of an intermediate part of the invention; and

(5) FIG. 4 is a section view of a cartridge equipped with an intermediate part of the invention.

(6) FIG. 5 is an exploded view of the various component elements of an intermediate part of another embodiment of the invention; and

(7) FIG. 6 is a section view of a cartridge equipped with an intermediate part of another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Example 1

Intermediate Part

(8) The intermediate part 100 as shown in FIGS. 1, 2, and 3 comprises a sleeve 1 and a wad 2 to which a dish 3 is fastened. The sleeve 1, which is of cylindrical section, is constituted by a cardboard tube comprising a front portion 11 that receives a metered quantity of shot, and a rear portion 12 in which the wad 2 is situated. For example, the tube may be made of spirally wound cardboard, which is available from cardboard manufacturers in various dimeters and in various grammages. The grammage is such that the thickness of the cardboard lies in the range 0.4 mm to 1 mm. Furthermore, the sleeve 1 has a diameter that is determined by the size of the cartridge into which the intermediate part is to be placed. For example, it is possible to use a tube that has an inside diameter of 17.4 mm, that is made of cardboard having a thickness of 0.6 mm (+/−0.1 mm), that thus has an outside diameter of 18.6 mm (+/−0.1 mm), and that is suitable for equipping a 12-gauge or “12-bore” cartridge. Four slits 13 that are equidistant and that are parallel to the axis of the sleeve 1 are provided in the front portion of the sleeve over a length of 18 mm, enabling the sleeve to peel open during firing, thereby splaying out to give shape to the spray of shot.

(9) Cardboard is a material of choice for achieving the desired objectives. It is strong while also having a certain amount of elasticity, thereby preventing it from tearing during the thrust from the gases. Furthermore, it is hydrophilic, at least when it is not subjected to any particular treatment, so that it absorbs any ambient humidity or moisture of any origin: puddles, rain showers, fog, and morning dew. As a result, it is digested rapidly by the microorganisms that develop on the cellulose of natural sites. The cardboard sleeve is thus 100% biodegradable and it disappears totally about three weeks after being fired, or even earlier if conditions are favorable, when it is left in a meadow or in a wood.

(10) The wad 2 is in the form of a solid cylinder occupying the rear portion 12 of the sleeve 1. The rear face 22 of the wad 2 is flush with the end of the sleeve 1, i.e. the rear face 22 of the wad 2 and the end of the sleeve 1 lie in the same plane, which is orthogonal to the axis of the sleeve 1. Its diameter is identical to the diameter of the sleeve 1, so that it is held by friction forces on being inserted by being pressed into the sleeve 1. In the present example, its diameter is 17.4 mm, like the inside diameter of the sleeve for a 12-bore, and its height is chosen to lie in the range 10 mm to 15 mm (adjusted as a function of the shot charge or shot load).

(11) The wad 2 is made up of ground cork granules (the size of the granules lying in the range 0.5 mm to 2 mm) amalgamated by means of a thermoplastic resin, added at a content by mass of in the range 0.5% to 0.8%. It is advantageous to use cork because it plays its part as a damper or shock absorber very effectively. It is also completely natural and without any toxicity either for fauna or for flora. The biodegradable binder is digested by the microorganisms in a few days, thereby releasing fragments of cork that disperse without causing any harm into the environment, so that they are then used and/or degraded gradually by the living organisms, as would be any woody debris.

(12) A cardboard wafer that has a thickness of 0.5 mm was stamped to obtain a dish 3 having an end wall 32 that had a diameter identical to the diameter of the wad 2 (17.4 mm in this embodiment) with a circular rim 31 of 3 mm. The outer face of the end wall 32 was pasted with a cellulose adhesive and fastened to the wad 2 at the end of the intermediate part. In a particular embodiment, a rigid disk 4 (see FIGS. 5-6) (not shown) that is of diameter identical to the diameter of the sleeve 1, and that is made of the same cardboard may be bonded adhesively to the wad 2 beforehand.

(13) Just like the sleeve 1, the dish 3 is digested rapidly by the microorganisms of natural sites, as is the rigid disk. The dish 3 is thus 100% biodegradable and disappears completely a few weeks after being fired.

Example 2

Cartridge

(14) The cartridge 200 shown in FIG. 4 includes an intermediate part 100 as described above. In conventional manner, the cartridge 200 is formed of the case 10, which is cylindrical and made of a plastics material of a type known per se. Its rear portion is mounted in the base or “head” 40 that is made of metal, e.g. of brass. The cartridge 200 contains the powder constituting the explosive charge 20 that is in contact with the primer 42. The shot 30 is received in the front portion 11 of the intermediate part 100, so that it is separated from the explosive charge 20. The explosive charge is confined to its compartment by means of the dish 3, the rim 31 of which provides sealing.

(15) In particularly advantageous manner, the case of the cartridge may be transparent, or at least translucent, in such a manner as to allow the sleeve it contains, and in particular the indications printed on said sleeve, to show through it. Specifically, while the cartridge 200 is being manufactured, it is possible to print information for users on the sleeve 1, such as the gauge or bore, the length of the case, or the brand of the manufacturer. Printing on cardboard is easy and remains visible lastingly, whereas the marking commonly performed on the case tends to fade away, which can cause accidents. Such marking is conducive to improving user safety, and without going as far as that, will be appreciated by users because it is practical.

Example 3

Ballistic Tests

(16) The intermediate part in example 1 was tested with 12-bore cartridges. About one hundred shots were fired at a target, and they were compared with shots fired under the same conditions with cartridges equipped with conventional models of wadding skirts. The results obtained were very satisfactory. No loss of pressure was observed during firing, nor were any disturbances in the spray of shot. The performance in terms of grouping of the impacts was excellent, denoting a uniform structural shaping of the cartridge and of the intermediate part. Comparatively, the ballistic qualities were better than those obtained with wadding having skirts made of plastic.

(17) Thus, a cartridge is provided that has wadding and a cup, that is environmentally friendly, and that has performance appreciated by hunters or shooters.