SHOTGUN CARTRIDGE OBTURATOR, METHOD FOR PREPARING A CARTRIDGE EQUIPPED WITH SAID OBTURATOR AND EQUIPPED CARTRIDGE

Abstract

The invention relates to a shotgun cartridge comprising a case (12) of internal diameter d.sub.INT and a base (14) with a primer (16), the powder (18), a wad (22) and the shot (24), as well as an obturator (20) arranged between the powder (18) and the wad (22), characterized in that the obturator (20) is made of biodegradable material with plastic deformation properties, and comprises a central disk (25) and ribs (26) together forming a one-piece element with the disk, the assembly having an outer diameter d.sub.EXT, the ribs (26) comprising upper ribs (27) and lower ribs (28), these ribs (26) forming a non-zero angle with the plane of the disk (25), the obturator having a nominal outer diameter d.sub.EXT, the ribs being able to take at least one other position in which said ribs (26) are in the plane of the disk (25), the outer diameter being D.sub.EXT. The invention also concerns a method for producing a shotgun cartridge.

Claims

1. Shotgun cartridge comprising a case (12) of internal diameter d.sub.INT and a base (14) with a primer (16), the powder (18), a wad (22) and the shot (24), as well as an obturator (20) arranged between the powder (18) and the wad (22), characterized in that the obturator (20) is made of biodegradable material with plastic deformation properties, and comprises a central disk (25) and ribs (26) together forming a one-piece element with the disk, the assembly having an outer diameter d.sub.EXT, the ribs (26) comprising upper ribs (27) and lower ribs (28), these ribs (26) forming a non-zero angle with the plane of the disk (25), the obturator having a nominal outer diameter d.sub.EXT, the ribs being able to take at least one other position in which said ribs (26) are in the plane of the disk (25), the outer diameter being D.sub.EXT.

2. Shotgun cartridge according to claim 1, characterized in that the diameter D.sub.EXT of the obturator (20) with the ribs in the plane of the disk (25) is greater than the inner diameter d.sub.INT of the case.

3. Shotgun cartridge according to claim 1, characterized in that the nominal outer diameter d.sub.EXT of the obturator (20) is less than the inner diameter d.sub.INT of the case (12).

4. Shotgun cartridge according to claim 1, characterized in that the obturator comprises a linking membrane (38) between the ribs (26).

5. Shotgun cartridge according to claim 1, characterized in that the obturator (20) comprises eight upper ribs (27) and eight lower ribs (28).

6. Shotgun cartridge according to claim 1, characterized in that the upper ribs (27) and the lower ribs (28) comprise two radial rectilinear edges (30) and a circular edge (32) forming the periphery of the obturator (20) with an upper circular edge (34) and a lower circular edge (36).

7. Shotgun cartridge according to claim 6, characterized in that the radial rectilinear edges (30) of the upper ribs (27) are staggered relative to the lower ribs (28).

8. Shotgun cartridge according to claim 1, characterized in that the upper ribs (27) form an angle of more than 0° and in that the lower ribs (28) form an angle of less than 0°, with the plane of the central disk (25).

9. Shotgun cartridge according to claim 8, characterized in that the upper ribs (27) form an angle of about 30° and in that the lower ribs (28) form an angle of about −30°, with the plane of the central disk (25).

10. Method for producing a shotgun cartridge according to claim 1, characterized in that it comprises the following steps: preparing a base (14) with the case thereof (12), said base comprising a primer (16) and a powder charge (18), introducing an obturator (20) into the case (12), introducing at least one wad (22) into said case (12), introducing the projectile (24) into said case (12), crimping the case (12).

Description

[0025] The present invention is now described in accordance with a non-limiting main embodiment, with reference to the accompanying drawings in which the different figures show:

[0026] FIG. 1: a front view of a cartridge with an obturator of the prior art,

[0027] FIG. 2: a front view of a cartridge with the obturator according to the present invention,

[0028] FIG. 3: a view from above of the obturator according to the present invention,

[0029] FIG. 4: a front view of the obturator according to the present invention,

[0030] FIG. 5: a front view of the obturator deformed by the compression generated by the explosion of the powder in the cartridge showing the dimensional variations,

[0031] FIGS. 6A and 6B: a view from above of the obturator in the case, a dotted line indicating the obturator immediately after the explosion of the charge,

[0032] FIG. 7A to 7D: a synoptic diagram of the method for producing and using a cartridge with the obturator according to the present invention.

[0033] FIGS. 1 and 2 describe a cartridge 10 comprising a case 12 and a base 14 equipped with a primer 16. The interior of the cartridge 10 contains the powder 18 placed in the region of the base 14 on which an obturator O and 20 is placed, the obturator O being an obturator of the prior art and the obturator 20 being the obturator according to the present invention. Each of the obturators O, 20 receives on top a wad 22, above which the shot 24, more generally the projectiles, is placed, in a known manner. The wad may be cup-shaped to better receive the shot.

[0034] The obturator 20 according to the present invention is shown in FIGS. 2 to 6, being shown deformed in FIGS. 5 and 6.

[0035] The obturator 20 comprises a central disk 25 with a thickness E and a diameter D, and has a lower face 20-1 and an upper face 20-2, lower and upper being considered with the cartridge placed vertically on its base.

[0036] The obturator 20 according to the present invention is manufactured in a single piece, the central disk having at least two upper ribs and at least two lower ribs 26, in this case eight upper ribs 27 and eight lower ribs 28, with which said central disk forms a one-piece element. The ribs 26 may resemble the petals of a daisy.

[0037] On the obturator 20, the upper ribs 27 and the lower ribs 28 number eight upper ribs 27 and eight lower ribs 28 respectively and spread outwards from the edge of the disk 25. Each of the upper 27 and lower 28 ribs comprise two radial rectilinear edges 30 and a circular outer peripheral edge 32, all the peripheral edges forming the periphery of the obturator 20 and thus an upper circular peripheral edge 34 and a lower circular peripheral edge 36. In the embodiment shown, each rib has a constant thickness e, said thickness e being less than E. The thickness E of the disk is less than or equal to twice the thickness e.

[0038] As can be seen in FIGS. 4 and 5, the angle of the ribs 26 relative to the plane of the central disk 25 is non-zero, viewed from the peripheral edge of the disk at the peripheral edge of the ribs. Looking at the disk 25 horizontally, the upper ribs 27 form an angle of more than 0° with the plane of the central disk 25. The lower ribs 28 form, symmetrically, an angle of less than 0°, also with the plane of the central disk 25. The angle varies depending on the caliber of the weapon and thus the diameter of the cartridge case, on the nature of the material, on the design of the cartridge and therefore on the wad or wads, and on the nature of the biodegradable material. Generally, the obturator gives complete satisfaction with any angle but tests will allow a person skilled in the art to quickly determine the optimum angle under routine working. The angle is more particularly between 20° and 40°.

[0039] Thus, the obturator comprises a central disk 25 and ribs 26 together forming a single-piece element, each rib 26 forming a non-zero angle with the plane of said disk 25.

[0040] The upper ribs 27 and the lower ribs 28 may or may not be connected by the radial rectilinear edges 30 thereof; in the present description said ribs are connected by a linking membrane 38. Because of its narrowness, said linking membrane 38 appears as a line. Said linking membrane 38 is placed between the ribs 26 and provides a preferably flexible connection between each of the upper ribs 27 and between each of the lower ribs 28, in particular to prevent deformation of the ribs during handling. Said linking membranes 38 have very little mechanical strength compared to the pressures and stresses that will later be involved when in use. In the plane of the disk 25, the upper ribs 27 are staggered relative to the lower ribs 28 such that the radial rectilinear edges of the lower ribs are angularly offset from the radial rectilinear edges of the upper ribs. Thus, and since the upper 27 and lower 28 ribs have the same geometry, the linking membranes 38 are not aligned along the longitudinal vertical axis. As can be seen in FIG. 3, the linking membranes 38 of the upper ribs 27 are advantageously positioned at the midpoint of the lower ribs 28 and vice versa, in order to maintain symmetry.

[0041] A deformable material with no resilient property is used for the obturator, which material is identical for the object in its entirety. The “no resilient property” characteristic refers to a material that is deformable but does not immediately recover its initial form once deformed. It is therefore a material of which the properties are referred to as “plastic,” not “resilient.” Thus if the ribs 26 are flattened, under stress, said ribs do not instantaneously return to the initial position when the stress ceases although a shape memory may be present.

[0042] From the point of view of geometry, the outer diameter d.sub.EXT of the obturator is smaller than the inner diameter d.sub.INT of the case in which said obturator is to be introduced. The diameter d.sub.EXT is the theoretical diameter of the obturator in the operating position with the ribs in the plane of the disk 25.

[0043] The present invention proposes an obturator geometry that allows a biodegradable material with plasticity properties to be used.

[0044] The method for producing a cartridge equipped with the obturator according to the present invention consists of the following successive steps: [0045] preparing a base with the case thereof, said base comprising a primer and a powder charge, [0046] introducing an obturator according to the present invention into the case, [0047] introducing at least one wad into the case, [0048] introducing the projectile, in this case the shot, [0049] crimping the case.

[0050] The introduction of the obturator is very easy as the outer diameter d.sub.EXT of the obturator is smaller than the inner diameter d.sub.INT of the case, as seen in FIG. 7A. Next, the other elements forming the cartridge, specifically the wad and projectile, are introduced in an entirely known manner before crimping, as seen in FIG. 7B. It will be observed that crimping, which consists of rolling the edges of the case on an operculum or folding the card into a star, which is also completely known, produces a reduction in the height of the case, which leads to initial pressure being applied to all the elements introduced into the cartridge and thus to the obturator, as seen in FIG. 7C.

[0051] Said pressure is limited but places the ribs 26 of the obturator in contact with the inner wall of the case 12.

[0052] The operation of the obturator 20 according to the present invention will now be described.

[0053] When the powder 18 is rapidly combusted and the explosion takes place in the region of the base 14, the role of the obturator 20 and the wad 22 is to transfer the energy generated by the explosion to the shot 24 to allow said shot to be projected. The mechanical behavior of the obturator is therefore fundamental to the firing quality.

[0054] It is therefore important that the join between the periphery of the circle formed by the upper circular edge 34 and the lower circular edge 36 is as airtight as possible relative to the inner wall of the case. As the excess pressure produced on the face of the obturator is on the side of the lower ribs 28 and on the lower face 20-1 of the disk 25, the obturator is subject to compression under the effect of the thrust generated by the explosion acting on said lower face of the disk 25 and on the lower ribs 28. The lower ribs 28 are therefore brought back to the plane of the disk.

[0055] At the same time, the upper ribs 27 are brought back to the plane of the disk by the movement of the obturator 20 which bears on the wad 22 topped by the shot 24, elements which are not yet subject to any action linked to the explosion in this phase, as seen in FIG. 7D. The lower ribs 28 meanwhile are compressed and rest against the upper ribs 27 immobilized against the wad. There is therefore a planar continuity between the ribs 26 and the disk 25. It will be noted with reference to FIGS. 6A and 6B that when flattened, as the theoretical diameter d.sub.EXT, shown by a dotted line, is greater than the inner diameter of the case d.sub.INT, the case which was constrained by the flattened obturator, deforms and is pressed against the cylinder, deforming said cylinder radially, said deformation being less than the theoretical deformation, until the outer wall of the case comes against the inner wall of the FC barrel. The inner wall of the FC barrel confines the outer wall of the case and thus the obturator radially and very significant radial pressure is produced from the recessed portion of the obturator.

[0056] The radial seal is extremely strong and at the same time leakages are negligible while the ballistic parameters are excellent.

[0057] In the central portion, because the radial rectilinear edges of the ribs with the linking membranes 38 thereof are staggered, the seal is reinforced even if one or more of the linking membranes 38 are torn as the deflector effect is totally dominant. During manufacture and post-manufacture handling, the linking membrane 38 may be partly or completely torn and therefore inoperative, but this does not degrade the seal performance and hence the ballistic values as the ribs 26 are pressed down by very significant pressure. Hence, almost all the thrust of the gases is transmitted to the obturator 20 which then bears on the wad 22, which distributes said thrust to the shot 24, and here too transmits almost all of said thrust.

[0058] The lower 28 and upper 27 ribs are therefore brought closer by the compression to which the obturator 20 is subject. The upper circular edges 34 and the lower peripheral edges 36 are also moved radially away from the disk 25 and are therefore pressed and rest against the inner wall of the case 12. Referring to FIGS. 6A and 6B, it will be observed that when flattened, as the theoretical diameter D.sub.EXT, shown as a dotted line, is greater than the inner diameter of the case d.sub.INT, the case in the cylinder of the FC barrel confining said case radially, very significant radial pressure is produced from the recessed portion of the obturator linked to the diametric differential. Said radial expansion compresses the circular edges 34 and 36 on the inner wall of the case 12, which is also pressed against the inner wall of the cylinder of the barrel. The peripheral seal is therefore provided and strengthened. The radial seal is extremely strong and leakages are negligible while the ballistic parameters are excellent.

[0059] From an environmental point of view, the material used to manufacture the obturator 20 may be biodegradable. At the moment of the explosion, the disk 25 and the upper ribs 27 are compressed on the wad 22, the lower ribs 28 are compressed on the upper ribs 27, the edges 34 and 36 are then compressed against the inner wall of the case 12, and the assembly, except for the membranes 38, is compressed but at no time stretched. The mechanical characteristics of biodegradable materials comply with the compression stresses applied to the obturator 20.

[0060] Biodegradable materials tend to change over time and lose plasticity for example or suffer dimensional variations. It will be observed that if, for example, the material becomes more brittle causing one or more ribs to break, the architecture allows the upper and lower ribs to be pressed together forming a continuous surface and compensating for said breakage. Similarly, if the diameter d.sub.EXT changes, the ribs compensate in diameter and the reduction in radial pressure will be miniscule and quite sufficient to provide a suitable seal.

[0061] This is a very important element as biodegradable materials change owing to the presence of organic charges, natural, plant-based fibers or powders, plant-based polymers or those produced by microbiological techniques. Therefore, some degradation over time necessarily occurs, this being the primary appeal of said materials and what is sought after said obturators have been used and dispersed in nature.

[0062] The hunting season in particular is of limited duration and cartridge-type ammunition bought in one year may be kept for one or more years before being used. Different types of shot may be bought depending on the game and the different caliber guns even though all the ammunition bought during a year has not been used, not forgetting the normal stocks that remain at the end of the season. It is therefore imperative that cartridges using an obturator according to the present invention retain their ballistic performance at least from one year to the next or even over a period of years. The main user parameter is ballistic performance but while a user may be prepared to pay a higher price for cartridges with ecological properties, the same user will not tolerate a loss of ballistic performance.

[0063] The obturator according to the present invention is biodegradable, enables radial compensatory expansion and allows uniform, constant transmission of thrust to develop over time.

[0064] It will be understood that the internal architecture may vary in terms of wads, the arrangement of the obturator, for example between two wads, but the obturator remains the same, as does the operation thereof. Similarly, the nature of the wads may vary depending on the application and projectiles. However, this does not form part of the present invention.