EP0435830B1 - Method for manufacturing cartridge cases for firearms and cases obtained thereby - Google Patents

Abstract

The method according to the invention, which allows the manufacture of cartridge cases for firearms of the type having three elements represented by a cylindrical tube (2), a strengthening part (3) which can be arranged in the tube (2) and a base (4) capable of fitting over the tube (2) provides for: the use of a strengthening part (3) obtained from an almost non-deformable material and already provided with at least one end-tooth (31) on the perimeter and protruding from the said part, the use of a base (4) having an open bottom and of different diameters provided for the formation of an annular tapered collar (43) defining a housing (45) in which can be received the anchoring tooth (31) of the strengthening part (3) and one of the ends (21) of the tube (2); and the formation of the case (1) by the insertion of the tube (2) into the base (4) in such a way that it protrudes beyond the portion (41) of smaller diameter of the base (4), by the insertion of the strengthening part (3) firstly into the base (4) and then into the tube (2) in such a way as to fold the respective end portion (21) until contact with the wall of the housing (45) defined by the collar (43) of the base (4) and finally by the folding of the portion of larger diameter (42) of the base (4) in such a way as to bring it into contact with the strengthening part (3). <IMAGE>

Description

The present invention relates to a method for manufacturing cartridge cases for firearms of the three-element type, and to the case thus obtained.

Currently the casings for firearms and in particular the casings of hunting cartridges and shooting, for economic reasons concerning both the production and the use of the fact that once used they are thrown in most cases, are manufactured in several parts joined together and formed only in the smallest part of valuable and expensive material such as for example a metal.

The most widely followed manufacturing process for the manufacture of "three-element" type sockets, as for example in patent FR-A-1 553 453, provides for the use of a plastic or paper tube, d '' a cylindrical reinforcement piece also of plastic or paper and a metal base.

The base has a cylindrical shape, is essentially closed at one of its ends and has, along the perimeter edge of this end, a bulge or collar defining inside the base a notch acting as a housing. The base also provides a central hole in which a capsule is introduced for igniting the powder. The tube is cylindrical and intended to be introduced into the base at least until it contacts the closed end of the latter. The tube could indeed have its peripheral end edge folded towards the axis of the tube itself for a reason which will be clarified later. The reinforcement piece is also cylindrical on the outside and is provided with a central hole which must be coaxial with the hole in the base to accommodate the capsule therein. The room reinforcement is likewise formed of deformable material, for a reason which will appear obvious from the description of the process carried out here.

For example, the reinforcement piece is introduced into one end of the tube and this end is introduced into the base at least until when it is in contact with the closed base of said base. If the tube has a folded edge as said above, the reinforcement piece is inserted into the tube and brought into contact with this folded edge. Then, after having correctly positioned the three elements and having properly retained them, a compression action is exerted on the reinforcement piece which, through this forcing operation, must fulfill two fundamental functions. The first is that of clamping the tube against the interior surface of the base and the second is that of radially deforming the end of the tube so as to force it into the housing defined by the collar of the base. It is obvious that during this operation the materials of the tube and especially of the reinforcement part are subjected to significant mechanical stresses which can irreparably damage this part, if they are not checked in a correct way. For example, taking into consideration the zone of the tube concerned by the reinforcement part and by the base, if a force having a force greater than that expected is exerted on the reinforcement part, it could result in too much crushing. strong of the tube and therefore also a weakening in traction, which would compromise the resistance during the discharge.

This complicated and delicate work step is in any case essential to avoid the risk that the tube, during the shot, separates from the base and enters the barrel of the rifle, which would lead to dangerous consequences.

The same working step also aims to ensure that the base of the socket, where the capsule is located and which consists of the reinforcement piece and the base, offers rigid resistance to the striker when the latter strikes the primer or capsule. The rigidity and resistance characteristics can be ensured only by the impossibility of relative slippages between the elements and must be calculated very precisely in order to avoid anomalous ignitions or the non-ignition of the primer and therefore of the powder. .

Another object of the invention which must be achieved by the same working step is that of eliminating or minimizing the losses of combustion gases which tend to occur between the tube and the reinforcement piece and which, by the deformation of the base, modify the dimensional structure of the socket.

There are many intrinsic problems; one must first take into consideration the need for machines that are very complicated from a technical point of view and of high power. Indeed, for the execution of this step it is necessary to exert a considerable force in a limited space such as the empty zone defined by the socket. In addition, the element which comes into contact with the reinforcement part and which exerts on it said compressive force must have a well-defined conformation so that it can exert this force correctly in order to ensure intimate union. of the three parts and the necessary rigidity of the base of the socket.

In addition, there are also many negative external factors that can hinder the operation and prevent the three parts from holding together. Among these prejudicial factors it is necessary to understand the dimensions reduced housing defined by the collar, the difficulty of penetrating uniformly and constantly the material forming the reinforcement piece and the tube in the housing of the collar in order to form the conformation commonly called "anchor tooth" and the return possible elastic of the material forming the reinforcement part.

All of the above is made even more difficult because of the problems which arise in controlling non-destructively, using technical or visual means, the perfect formation of the perimeter tooth for anchoring the reinforcement piece, which is practically the only element capable of ensuring the connection between the three elements.

The object of the present invention is therefore to enable the manufacture of cartridge cases, of the "three-element" type, for firearms, for which it is possible, during any discharge step, to maintain the junction between said three elements without requiring the intervention of considerable compressive forces which during the assembly step of the sleeve could deform one or more elements forming the sleeve and modify the geometry thereof.

Another object of the invention is to allow the manufacture of the sockets in a simple, rational and economical manner, by eliminating the drawbacks mentioned above.

• la figure 1 montre, en coupe axiale, les trois éléments formant la douille de cartouche pour armes à feu suivant la présente invention, ces éléments étant prêts pour la mise en oeuvre du procédé de l'invention;
• les figures 2 à 4 montrent, en coupe axiale, les trois éléments représentés sur la figure 1 pendant les étapes faisant partie du procédé suivant l'invention;
• la figure 5 montre, en coupe axiale, une forme d' exécution différente de la douille représentée sur la figure 4; et
• les figures 6 à 8 illustrent trois formes différentes d'exécution de la pièce de renforcement représentée sur la figure 1.

The invention, as characterized in the claims, solves the problem addressed by a method for manufacturing cartridge cases for firearms and by a case obtained by this process, the characteristics and advantages of which will become more clearly apparent of the following detailed description of a preferred embodiment given simply non-limiting example using the appended drawings, in which:

• Figure 1 shows, in axial section, the three elements forming the cartridge case for firearms according to the present invention, these elements being ready for the implementation of the method of the invention;
• Figures 2 to 4 show, in axial section, the three elements shown in Figure 1 during the steps forming part of the method according to the invention;
• Figure 5 shows, in axial section, a different embodiment of the socket shown in Figure 4; and
• FIGS. 6 to 8 illustrate three different embodiments of the reinforcement piece shown in FIG. 1.

Referring to the appended figures, the method according to the invention makes it possible to manufacture sockets, generally indicated in 1, composed of three elements, that is to say a cylindrical tube 2, a reinforcement piece 3 to be inserted in the tube 2 and a base 4.

The method in question provides above all that the reinforcing piece 3 is made of a material which is substantially non-deformable and that it is already shaped so as to have at least one perimeter end tooth 31 projecting from the reinforcing piece. The perimeter tooth 31 has an outside diameter of maximum overall dimensions 3d larger than the outside diameter 2d of the tube 2 and it is tapered towards the cylindrical perimeter surface of the reinforcement piece 3. Obviously the term "non-deformable" should not be taken in an absolute sense, but it only means that the reinforcement piece 3 does not undergo significant deformations during all the steps of the process according to the invention. In addition, by the term "undeformable" we want to differentiate very precisely the reinforcement piece 3 characterizing the process according to the invention of the traditional type reinforcement pieces which were drastically deformed with modification of their geometric shapes and their mechanical characteristics: indeed, the strong compression was also intended to increase the rigidity of the base of the base, but to obtain this result, it was necessary to drastically reduce the possibilities of choosing the profiles of the part of the reinforcing part which, when the cartridge is finished, is in contact with the powder.

In addition, the method according to the invention provides that the base 4 is also suitably shaped and that it is formed of two portions 41 and 42 coaxial and of different internal diameters, 41d and 42d respectively. The smaller diameter 41d is essentially equal to the outside diameter 2d of the tube 2 while the larger diameter 42d is essentially equal to the maximum diameter 3d of the perimeter tooth 31 of the reinforcement piece 3. The connecting portion 43 portions 41 and 42 constitute for the base 4 a tapered collar of nanometer corresponding to the perimeter tooth 31 and defining, inside the collar 43, a housing indicated in 45 of dimensions sufficient to receive both the perimeter tooth 31 and the one end of the tube 2.

• introduction du tube 2 dans le culot 4 de manière que l'une des extrémités 21 du tube 2 dépasse la ligne, indiquée en 44, séparant du collier 43 la portion 41 sur une longueur 1 non inférieure à l'extension axiale de la dent périmétrale 31 (voir la figure 2);
• introduction de la pièce de renforcement 3 dans le culot 4 et dans l'extrémité 21 du tube 2 jusqu'a forcer la dent périmétrale 31 dans l'extrémité correspondante 21 du tube 2 et de sorte que cette extrémité 21 soit déformée et amenée en contact avec la paroi du logement 45 (voir la figure 3); et
• repliement de la portion 42 du culot 4 vers l'axe de ce dernier et jusqu'a l'amener au contact de la pièce de renforcement 3 (voir la figure 4).

Taking into consideration a reinforcement piece 3 and a base 4 structured in the manner described above, the method according to the invention provides for the following steps:

• introduction of the tube 2 into the base 4 so that one of the ends 21 of the tube 2 exceeds the line, indicated at 44, separating from the collar 43 the portion 41 over a length 1 not less than the axial extension of the perimeter tooth 31 (see Figure 2);
• introduction of the reinforcement piece 3 into the base 4 and into the end 21 of the tube 2 until forced the perimeter tooth 31 in the corresponding end 21 of the tube 2 and so that this end 21 is deformed and brought into contact with the wall of the housing 45 (see FIG. 3); and
• folding of the portion 42 of the base 4 towards the axis of the latter and until bringing it into contact with the reinforcement part 3 (see FIG. 4).

The length 1 of the end 21 of the tube 2 can vary from the minimum value described, which allows the use of a reinforcement piece 3 whose perimeter tooth 31 is inserted directly in contact with the interior wall of the portion 42 of the base 4 (see Figure 4), up to a value greater than the axial dimension of the tooth 31 measured parallel to its generatrix, so that the end 21 of the tube 2 extends towards the portion 42 of the base 4 au- beyond the perimeter tooth 31 (see Figure 5). In the latter case, the diameter 3d of the perimeter tooth 31 must be substantially equal to the diameter 42d of the portion 42 of the base 4 minus twice the thickness s of the tube 2.

It is obvious that the method according to the present invention provides for using already shaped elements and assembling them by joining them together, by means of the exploitation of their conformation which remains unchanged during all the stages of assembly.

In other words, the maintenance of the connection between the tube 2, the reinforcement piece 3 and the base 4 is ensured by geometric shapes which are perfectly visible and which can be checked before the assembly step and which remain unchanged during the same step.

This means that the machine necessary to block the three elements reciprocally, namely reinforcement piece 3, tube 2 and base 4, is relatively simple and inexpensive, especially when compared to those commonly used. This results in a drastic reduction in overhead costs for the production of the sockets so as to achieve significant advantages in terms of economy of labor, raw materials and maintenance of the installations. In current installations, in fact, because of the large forces at play which act in very small spaces such as for example the interior of the tube, it is necessary to carry out continuous maintenance of the machines with greater precision and in particular of the machine in charge of the compression. From the point of view of the raw materials, their consumption is undoubtedly lower since the pellet is open instead of being closed as in the known art. In addition, thanks to the method of the invention, it is possible to eliminate the folding operation of an edge of the tube 2 in order to improve the connection between the three elements.

If we now look at a socket 1 obtained by implementing the method of the invention and illustrated in FIG. 4, we can already notice that it consists of a tube 2 surrounded by a base 4 with open bases and by a reinforcement piece 3 inserted inside the tube 2 and shaped so as to have, at one of its ends, a perimeter tooth 31 projecting from the piece 3 itself.

Because the reinforcement piece 3 does not undergo a significant deformation during the assembly step, it can be given the geometrical conformation which allows the socket 1 the best functioning and the best ballistic performance.

For example, the part 38 of the reinforcing part 3 intended to come into contact with the powder, which can for example be in the form of a hollow as shown in the appended figures, can also be provided with reliefs 33 arranged along the periphery of an axial hole 32 formed in the reinforcement part 3 for housing a capsule 5 for igniting the powder. The reliefs 33 have the task of preventing the powder 6 which will be introduced and compressed in the hollow 38 from being able to smother the flame of the capsule 5 housed in the respective hole 32. In other words, the reliefs 33, for example in the form of strips extending along radial directions of the hole 32, serve to increase the flame front for the capsule 5.

The axial hole 32 of the reinforcement piece 3 can be produced in different ways in order to allow the accommodation inside of it of different types of capsules 5: for example, a rigid element 34 can be provided inside the hole 32 forming an anvil for a capsule of known type called "Berdan" (see Figure 7).

Again (see FIG. 6), the reinforcement piece 3 can have a perimeter groove 35 outside. Between the groove 35 and the hollow 38 there is the interposition of a partition 37 which can bend under the push of the powder during of the shot. In this embodiment, for example, provision is made for the creation of a wall 37 capable of bending and this in harmony with the concept described above of sensitive non-deformability of the reinforcement piece 3. In fact the wall 37 does not undergo any deformation during the stages of assembly of the three elements forming the bush 1 and under the action of the forces at play during these stages, but it undergoes a deformation, which on the other hand is expected, after these stages and when it is subjected to forces much higher in absolute value than those exerted during the stages of the process according to the invention.

In Figure 8 there is shown an embodiment particularly advantageous as regards the saving of raw materials: the reinforcing part 3 is in fact provided, on the side on which the edge of the portion 42 forming part of the base 4 is provided for, relief means 36 obtained from different ways, for example through blind holes. This is made possible by the fact that the reinforcing part does not undergo any considerable deformation during the assembly steps of the sleeve 1 and therefore, since its conformation does not undergo any change, it can be provided in any shape. provided it has the perimeter tooth 31.

It is obvious that, being able to vary almost at will the geometric shape of the reinforcement piece 3 as a function of the characteristics which it is desired to give to the socket, which does not happen for the reinforcement pieces of the known art, this part 3 becomes "active", since a variation in its door shape has a different behavior from the cartridge.

Claims (14)

1. Method for manufacturing cartridge cases for firearms of a type having three parts represented by a cylindrical tube (2), a reinforcing piece (3) to be inserted inside one end of the tube (2), and a cap (4) able to surround at least the end of the tube (2) involved with the reinforcing piece, which is formed so as to have, at one end, a shoulder or peripheral anchoring tooth (31) projecting laterally beyond the reinforcing piece (3); the said peripheral tooth (31) having an external diameter with a maximum dimension not less than that of the external diameter of the tube (2) and tapering towards the cylindrical peripheral surface of the reinforcing piece (3), characterised in that it provides for:

   - the reinforcing piece (3) to be produced from material which is substantially non-deformable;

   - the cap (4) to be produced with open bases and in two consecutive coaxial portions (41, 42) having different internal diameters (41d, 42d); the smaller (41d) of the two internal diameters being substantially equal to the external one of the tube (2) and the larger one (42d) being substantially equal to the external diameter of the peripheral tooth (31) on the reinforcing piece (3); the connection region (43) between the two portions (41, 42) of the cap (4) with different internal diameters being tapered in a shape corresponding to that of the peripheral tooth (31) on the said reinforcing piece (3) and constituting a ring (43) forming a housing inside the cap (4) intended to receive the said peripheral tooth (31) on the reinforcing piece and the end (21) of the tube (2); in that it provides for the following stages:

   - insertion of the tube (2) into the cap (4) so that one of the ends (21) of the tube (2) passes beyond the joining line (44) between the portion with the smaller diameter (41) and the ring (43) on the cap (4) over a portion (21) with a length (1) which is not less than the axial extension of the said ring (43);

   - insertion of the reinforcing piece (3) into the portion of the cap (4) with the larger diameter (42) and into the tube (2) until the tooth (31) anchoring the reinforcing piece (3) is forced against the corresponding free end (21) of the tube (2) and until the latter is forced, by means of the said anchoring tooth (31), which has remained undeformed, against the ring (43) on the cap (3) so that this end (21) of the tube (2) adheres perfectly against the surface of the housing defined by the said ring (43);

   - folding, by crimping, rolling or otherwise, of the portion of the cap (4) with the larger diameter until it is brought into contact with the reinforcing piece (3) contained inside it.
2. Method according to Claim 1, characterised in that the external diameter (3d) of the peripheral tooth (31) on the reinforcing piece (3) is substantially equal to the largest internal diameter (42d) of the said cap (4) less twice the thickness of the said tube (2).
3. Method according to Claim 1, characterised in that the said tube (2) passes beyond the joining line (44) between the portion with the smaller diameter (41) and the ring (43) on the cap (4) over a portion (21) with a length (1) which is not less than the axial extension of the said ring (43) measured parallel to one of its generatrices.
4. Method according to Claim 1, characterised in that the said tube (2) passes beyond the joining line (44) between the portion with the smaller diameter (41) and the ring (43) on the cap (4) over a portion (21) with a length (1) which is not less than the axial extension of the said ring (43) measured parallel to one of its generatrices and such that, when the reinforcing piece (3) is completely inserted into the cap (4) and tube (2), the latter does not project from the said reinforcing piece (3).
5. Method according to Claim 1, characterised in that the said tube (2) passes beyond the joining line (44) between the portion with the smaller diameter (41) and the ring (43) on the cap (4) over a portion (21) with a length (1) which is not less than the axial extension of the said ring (43) measured parallel to one of its generatrices and such that, when the reinforcing piece (3) is completely inserted into the cap (4) and tube (2), the latter projects beyond the said reinforcing piece (3) and is compressed between the surface of the corresponding base of the cap (4) and the edge of the cap (4) folded over the latter.
6. Case of the type consisting of three parts represented by a cylindrical tube (2), a reinforcing piece (3) inserted into the tube (2) and a cap (4) surrounding the end of the tube (2) involved with the reinforcing piece (3), which is formed so as to have, at one end, independently of the stage of assembly of the case, a continuous peripheral anchoring tooth (31) intended to be housed, together with one of the ends (21) of the tube (2), in the housing (45) defined by the ring (43) on the cap (4), the peripheral tooth (31) on the reinforcing piece (3) gripping the corresponding end (21) of the tube (2) against the internal wall of the said ring (43) defining the said housing (45), and obtained by implementing the method according to the preceding claims, characterised in that the reinforcing piece (3) is produced from a substantially non-deformable material, and the said cap (4) is cylindrical and tubular in shape and has both bases open and of different diameters so as to form the said ring (43); the end rim of the portion (42) of the cap (4) with the larger diameter being folded towards the axis of the latter so as to close off the said housing (45) defined by the ring (43) and thus grip the peripheral tooth (31) on the reinforcing piece (3).
7. Case according to Claim 6, in which the reinforcing piece (3) has an axial hole (32), characterised in that it has, at the end of the said axial hole (32) in the reinforcing piece (3) and on the side of the latter intended to come into contact with the powder (6), a plurality of projections (33) able to prevent the powder contained in the tube (2) from smothering the flame from the primer (5).
8. Case according to Claim 7, characterised in that the projections (33) offered by the said reinforcing piece (3) in the area of the respective axial hole (32) and on the side intended to come into contact with the powder consist of an equal number of blades disposed along radial directions of the reinforcing piece (3).
9. Case according to Claim 1, characterised in that the axial hole (32) in the said reinforcing piece (3) has the same shape as the primer (5) which is housed inside it.
10. Case according to Claim 9, characterised in that the said reinforcing piece (3) has, inside its axial hole (32), a component (34) which is coaxial with the hole and which forms an anvil for the primer (5) which is to be housed inside the same axial hole (32) which is not completely occupied by the said component in the form of an anvil.
11. Case according to Claim 6, characterised in that the said reinforcing piece (3) is formed so as to have, independently of the stage of assembly of the case, a conformation which is a function of a better ballistic efficiency on its part and a higher intrinsic safety level.
12. Case according to Claim 6, characterised in that the said reinforcing piece (3) is formed so as to have, independently of the stage of assembly of the case, a conformation which makes it able to yield axially, at least over its portion which is furthest inside the said tube (2), under the thrust exerted by the powder (6) during combustion.
13. Case according to Claim 12, characterised in that the said reinforcing piece (3) has a peripheral groove (35) separated from the powder by means of a partition (37) which is sufficiently thin for it to be able to flex under the thrust exerted by the powder (6) during combustion.
14. Case according to Claim 6, characterised in that the said reinforcing piece (3), on its side which is not intended to come into contact with the powder, has at least one notch or relief hole (36).

Images