Striking projectile with hard core and drawing guide part

(57) The bullet is formed by a core (1) 8 by a front tip (2), the core (1) being made of a hard metal or hard metal alloy and / or a metal or metal alloy of increased density. The bullet is surrounded at the rear of its tip (2) by a cylindrical guide portion (3) of ductile metal.

The portion (4) of the core (1) that is surrounded by the guide portion (3) is provided with corrugations (5, 6) and the outer surface of the guide portion (3) is also formed in the form of a profile of these corrugations (5,6).

<td> 271</td><td> 480</td>

<td> (11)</td><td></td>

<td> (13)</td><td>B2</td>

<td> (51)</td><td>Int. Cl.⁵P 42 V 12/06</td>

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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piercing projectile and a hard core and a traction guiding portion of 40 mm or less comprising a core having a front tip and made of hard metal or hard metal alloy and / or metal or metal alloy of increased density . This bullet is surrounded at the rear of its tip by a cylindrical guide metal part, and the core part which is surrounded by a guide part is provided with undulations. The guide portion is seated on this core portion such that the inner surface of the guide portion is connected axially and circumferentially to said core portion by elevating and recessing the core portion.

Known piercing bullets are generally formed with a shell made of a ductile metal or alloy, such as copper or brass, and which surrounds a hard metal core such as hardened steel or lead-coated tungsten carbide.

The main disadvantages of these bullets are that the connection between the outer traction sheath and the inner hard core is not perfect. During the firing of the projectile by the action of the screw grooves provided inside the barrel of the gun during the firing occurs slipping between the shell and the hard core, which adversely affects the effect of the piercing missile.

In the embodiment described in French Patent No. 2,536,527, the piercing missile core is provided at its rear with a Morse taper which is embedded in a complementary cone provided within the guide portion or ductile metal shoe, thus covering the partially hard core. . This interconnection makes it possible to create good conditions for rotational movement of the core. Therefore, this bullet has a satisfactory breakdown effect. Unfortunately, this combination of Morse taper or self-locking taper is difficult to combine with large-scale industrial production. Indeed, the use of a Morse taper requires high manufacturing accuracy to create a perfect clearance-free connection between the guide portion and the back surface of the core. In this embodiment, the undulations are arranged on the outer surface of the guide portion, thereby reducing friction between the outer surface and the grooves provided inside the barrel of the firearm. Generating these corrugations by machining is expensive and often causes damage to the base material.

French Patent Specification No. 2,191,718 discloses a piercing bullet having a hard core, the back of which is covered by a guide portion or a shoe of pulling material. The attachment of this guide portion to the core is accomplished by welding, soldering, gluing, pouring or metal coating. These mountings are also not easy and would be very expensive in industrial production.

French Patent No. 764,833 discloses a piercing bullet having a hard core surrounded by a soft metal sheath which is attached to the core by means of a spinning process or a taper to ensure that the soft metal penetrates into the recesses formed on the the core surface. However, the outer surface of the wrapper retains its smoothness, causing the wrapper to cause increased friction during its insertion into the interior of the barrel of the firearm.

The above-mentioned disadvantages can be overcome by the penetrating bullet according to the invention, characterized in that the inner surface of the guide portion which is in contact with the core parts has a profile copying the corrugation of this core part and the outer surface of the guide part is also shaped .

A further advantageous embodiment of the bullet according to the invention is that the bullet tip is attached to the core part by means of an annular shoulder whose radial width corresponds to or less than the wall thickness of the guide part, the edge of the guide part being mounted on the annular shoulder. A bullet is also advantageous in that the core portion opposite the bullet tip has a frusto-conical surface whose smaller base forms the rear end of the core part, and that the inner surface of the guide portion is formed as a complementary frusto-conical surface of the frusto-conical surface. The guide portion may be provided with a rear wall adjacent the rear end of the core.

The main advantages of the solution according to the invention are that not only is it possible to obtain a perfect connection between the guide part and the core, but that economically advantageous industrial production in large batches is also possible. This is particularly because there is no need to maintain the dimensions of the guide portion and the core with high precision, since the deformations made during joining make it possible to compensate for certain deviations from the exact dimensions. Furthermore, the contact surface between the outer surface of the projectile and the grooves of the firearm barrel is reduced. At the same time, even when using a cylindrical guide portion, it is possible to obtain in a single operation that requires no machining or additional processing, a perfect mechanical connection between the guide portion and the core while creating a corrugation of the guide portion surface to reduce friction inside the barrel without adversely affecting the ballistic properties of the missile.

Further details and advantages of the subject matter of the invention will become apparent from the description of an exemplary embodiment, which is explained in more detail in conjunction with the drawings.

Fig. 1 schematically shows a plan view of the core and a longitudinal section of a guiding portion of a missile according to the invention. Giant. 2 shows a split view of the guide portion and the core prior to joining them.

FIG. 3 is a longitudinal cross-sectional view of the guide portion slid onto the core, which assembly is inserted into the solenoid of the electromagnetic forming apparatus.

FIG. 4 is a partial cross-sectional front view of the hub of the present invention;

As can be seen from the embodiment of Fig. 1, the bullet has a caliber of 40 mm or less, the core 2 having a front tip 2 of the classic angular shape. This core 2 is made of a hard metal or hard metal alloy and / or a high density metal or metal alloy, such as hardened steel, and is surrounded in the rear region of its tip 2 by a guide portion 3 having substantially cylindrical shape and is made of a ductile metal such as copper or brass. 5 of the core part 4, which is surrounded by the guide part 3, is provided with elevations 5 and recesses 6 and the guide part 2 is connected to this core part 4 by radial pressure so that the inner surface of the guide part 2 is^{e 3} by means of said core part 4 connected axially and in the circumferential direction by means of an elevation 5 ^and Counterbore 6 Part 4 Core 2 *

According to the invention, the guide part 3 is connected to the part 4 of the core 2 by electromagnetic forming,

In the illustrated embodiment, the knuckle-shaped tip 2 of the core 2 is attached to the core part 4 surrounded by the guide part 3 by means of an annular shoulder 7 whose radial width corresponds substantially to the wall thickness of the guide part 3 whose edge rests on the annular part. shoulder 7.

As shown in FIG. 1, the elevations 5 and recesses 6 provided on the core portion 4 are annular corrugations and the inner surface of the guide portion 3 in contact with the core portion 4 assumes the profile of the corrugations. In addition, the outer surface of the guide 3 forms corrugations 8 which follow the corrugation profile formed by the elevations 5 and depressions 6 provided on the core part 4. Thus, the profile of these corrugations 8 provided on the outer surface of the guide part 3 is predetermined by the corrugation profile. by elevations 5 and recesses 6 on the outer surface of the core portion 4 *

The maximum diameter of the arc-shaped tip 2 is slightly smaller than the caliber of a firearm,

The maximum diameter 4 4 of the core part 4 is smaller than the maximum diameter d o by such that the wall thickness e of the guide part 3 is sufficient to allow its deformation when it comes into engagement with the grooves of the firearm barrel. This thickness 6 is of the order of millimeters. The ripple amplitude 8 ee is between 0.5 and 1 mm.

The corrugations formed by the elevations 5 that are provided on the core portion D are formed such that the maximum diameter d ^ is equal to dg-2 £, where dg is as large as the bullet caliber, and the minimum diameter d ^ of the guide portion 3 is equal to d ^ * 2e, where d ^ is to be as large as the minimum diameter of guide portion 3, which is as large as the maximum diameter d_xin the embodiment shown in FIG. 1.

The corrugations 8, the profile of which in the example shown in FIG. 1 consists of the same consecutive convex or concave circular arcs, have at least two arcs forming protrusions which ensure perfect guidance of the bullet inside the barrel while reducing friction. Otherwise, the amplitude of these ripples 8 is relatively low and their radius is considerably large in order to avoid adversely affecting the aerodynamic properties of the projectile.

It can also be seen from FIG. 2 that the core portion 4 has a substantially frustoconical surface 9 at its end facing away from the tip 2, the smaller base 10 of which is formed at the rear end of the core portion 4. substantially as a complementary frustoconical surface with respect to this substantially frustoconical surface of the core portion 4, wherein the rear wall 11 of the guide portion 3 ee abuts the rear end, i.e. the smaller base 10 of the frustoconical surface of the core Ъ

Referring now to Figs. 2 and 3, a method for manufacturing a piercing projectile is shown in Fig. 1.

This process has the following stages.

A core 1 is formed which has, in the rear part of its tip 2, a substantially cylindrical part 6 having a smaller diameter and which is provided with recesses 6 and elevations 5, obtained for example by turning.

A guide portion 3 is formed which is substantially cylindrical in shape and whose inner maximum diameter d d is substantially equal to or slightly greater than the maximum diameter of the core portion 4 which is intended to surround the guide portion 3. The length of the inner opening of the guide portion 3 is slightly less than the length lg of the core portion 4.

Finally, the guiding portion 3 is slid onto the core portion 14 having a substantially cylindrical shape and coupled to the guiding portion 3 with the core portion 14 by electromagnetic forming by means of the device shown schematically in Fig. 3.

This electromagnetic forming apparatus has been described in particular in the ''ΕΤΙΜInformations' Revision No 80-81-June 1983 entitled Electromagnetic Forming¹’.

This device comprises a solenoid 13 which surrounds the guide portion 3 mounted on the core portion 4. This solenoid 13 is connected to a power generator 14. A capacitor 11 is provided parallel to the terminals of the solenoid 13. The electrical circuit further comprises a charge switch 16 and a discharge switch 17.

Upon closing the switches 5 (i.e., first the charging switch 16 and then the discharge switch 17), the solenoid 13 is passed through a damped sinusoidal electric current, creating a variable magnetic field within the solenoid 13. This magnetic field generates a force that radially presses the guide portion The radial pressure acting on the guide part 3 is essentially given by * *

POB² / 8, where P is the pressure in pascals and В is the induction in teslaoh.

Thus, the solenoid 13, which induces 30 tesels, causes a pressure of about 7 x 10 x pascals, or 7000 bar.

This pressure might appear to be low for mechanical deformation of the material, but because it is developed within a few microseconds, it impulses a force in the material, so-called plasticizing effect, and therefore substantial deformation. In this case, the classical laws of material resistance can no longer be used and it is necessary to switch to the use of plasticity theory, in particular the modulus of dynamic elasticity or the apparent limit of variable elasticity *

The brass or brass used for the guiding part 3 and the steel used for the core JL form an ideal material connection for performing the electromagnetic forming method

The use of this method is particularly advantageous for adaptation in the industrial production of large series because it does not require the preparation of the pieces to be used with high precision and allows a perfect and efficient connection between the guide part 3 and the core 1 * to be obtained.

A further advantage of this method lies in the fact that it makes it possible in one single operation to produce corrugations 8 on the surface of the guide part 3, which make it possible to reduce the friction inside the firearm.

The guide part 2 can also be obtained from a simple drawn tube. Moreover, it is not necessary to produce corrugations provided on the core 2 'with great precision, since electromagnetic forming will provide a smooth surface on the corrugations 8 of the guide portion 2, even if corrugations of the core 2 are not formed with great precision. This fact even goes so far that even the surface of the core 2 not machined with great precision, i.e. with surface micronerity residues, is advantageous for the connection between the guide part 2.^and core 1,

After performing the described operation, it is sufficient to insert the bullet into the classic cartridge 18, ^viz4, after it has been filled with dust, the cartridge is ready for use.

It goes without saying that the invention is not limited to the exemplary embodiments described above and that many modifications may be made.

Thus, for example, it is possible to modify the shape of the undulation which is disposed on the core portion 4 differently from that shown in FIG.

Among other things, for example, the guide portion 2 can be stripped of the bottom, i.e. substantially the rear wall 11, and a simple drawn tube can be used, which further reduces production costs.