EP0425379B1 - Subcalibre projectile comprising a core, a sabot and a jacket - Google Patents

Abstract

The technical field of the invention is that of spin-stabilized subcaliber projectiles including a core integral with a sabot, and a sleeve. The sleeve includes a rear annular area lodged in a corresponding groove in the sabot and providing gastightness, wherein: the sabot includes, toward the front of the projectile, a cylindrical crown having an edge bordering the band groove; the crown includes at least three notches, separated by castellations, and extending axially at least to the band groove; the sleeve follows a profile complementary to that of the sabot, so that it enters into the notches; and the projectile possesses means for separating the sleeve into several sectors under the effect of the centrifugal force, at the time the projectile leaves the gun muzzle. Application to medium-caliber ammunition.

Description

The field of the present invention is that of gyro-stabilized sub-calibrated projectiles comprising a core secured to a shoe and a jacket.

Such projectiles include a core of dense material such as tungsten, which is made to rotate with a sabot to the caliber. The sabot wears a sealing belt which takes the scratches from the barrel of the weapon and communicates the rotation to the core. The shirt is integral with the shoe and surrounds the core, its function is to maintain the latter radially and possibly axially relative to the shoe.

The patent FR2131393 describes a projectile of this type in which the plastic jacket is overmolded on the shoe and the core, and comprises six incipient fractures, produced in an axial direction, and regularly distributed.

The belt is here integral with the shirt, which makes it possible to reduce the mass of the hoof and to simplify the manufacture of the projectile by allowing only one overmolding operation to be carried out.

The axial attachment of the shoe and the core is obtained by clamps, carried by the shoe, coming in grooves made at the rear part of the core.

However, the difficulty of developing such a shirt-shoe connection is due to the compromise which it is necessary to obtain between its resistance to the constraints of the shot and the fragility which it is essential to give it to ensure rapid release. from the nucleus to the exit of the barrel of the weapon.

Indeed, a rupture of the jacket occurring inside the tube risks spreading to the belt, thus causing a gas leak which is detrimental to the good subsequent behavior of the projectile.

Conversely, a reinforcement of the thickness of the jacket at the connection zone with the part constituting the belt risks preventing good separation of the shirt and the shoe and the release of the core.

US-A-4,841,861, which forms the basis of the preamble of claim 1, describes an under-calibrated gyro-stabilized projectile close to that according to the invention intended to be fired from a weapon, of the type comprising a core housed in a bore of a shoe and in a jacket which has a rear annular zone housed in a corresponding groove in the shoe to constitute the gas tightness belt. Means for separating the jacket into several sectors are provided. However, this patent does not describe specific areas of rupture of the liner leading to regularity in the formation of liner sectors.

It is the object of the invention to propose a sub-calibrated projectile making it possible to overcome such drawbacks.

• des amorces de rupture réalisées sous la forme d'amincissements de l'épaisseur de la chemise, amorces s'étendant à partir des créneaux du sabot axialement sur sensiblement toute la longueur de la chemise et régulièrement réparties angulairement, l'ensemble des demi-plans dits de rupture qui sont définis comme les demi-plans passant par l'axe du projectile et contenant une amorce de rupture, définissant également des demi-plans dits demi-plans radiaux principaux qui sont les demi-plans bissecteurs internes des demi-plans de rupture,
• une répartition des encoches telle que, d'une part l'ensemble des encoches est symétrique par rapport à un demi-plan radial principal quelconque, et d'autre part, dans le cas où les demi-plans principaux coupent des créneaux, la largeur de ces derniers ainsi coupés ne décroît pas suivant une direction radiale de l'extérieur vers l'intérieur du sabot et dans le cas où les demi-plans principaux coupent des encoches la largeur de ces dernières ainsi coupées ne décroît pas suivant une direction radiale de l'intérieur vers l'extérieur du sabot.

Thus the subject of the invention is a gyro-stabilized sub-calibrated projectile intended to be fired from a weapon and of the type comprising a core disposed in a bore of a sabot and a jacket comprising a rear annular zone housed in a corresponding groove of the shoe and constituting a gas tightness belt, the shoe comprising, on the front side of the projectile, a cylindrical crown carrying a rim delimiting the belt groove, the crown comprising at least three notches, separated by slots and s 'extending axially at least as far as the belt groove (8), the shirt comprising a profile complementary to the shoe such that it penetrates inside these notches, the projectile comprising means ensuring the separation of the shirt into several sectors at the exit of the tube, of the weapon under the effect of the force centrifugal, characterized in that the means ensuring the separation comprise:

• primers of rupture produced in the form of thinning of the thickness of the jacket, primers extending from the slots of the shoe axially over substantially the entire length of the shirt and regularly distributed angularly, all of the half-planes so-called rupture which are defined as the half-planes passing through the axis of the projectile and containing a rupture initiator, also defining so-called main radial half-planes which are the internal bisector half-planes of the half-planes of break,
• a distribution of the notches such that, on the one hand, the set of notches is symmetrical with respect to any main radial half-plane, and on the other hand, in the case where the main half-planes intersect slots, the width of the latter thus cut does not decrease in a radial direction from the outside towards the interior of the shoe and in the case where the main half-planes cut notches the width of the latter thus cut does not decrease in a radial direction of inside to outside of the hoof.

The rim makes it possible to clearly separate the belt part from the rest of the shirt, which ensures the good performance of this belt, the slots allow the two parts of the shirt thus delimited by the rim to be joined together.
The notches extend axially at least as far as the belt groove and the complementary profile of the shoe penetrates inside these notches.

The incipient fractures starting from the slots, a possible beginning of crack at their level inside the barrel of the weapon will not propagate to the belt.

The distribution proposed for the notches relative to the initiations of rupture of the jacket as well as the rules of variation of their width make it possible to ensure the separation of the jacket into several sectors at the outlet of the barrel of the weapon.

According to other characteristics, each notch is delimited by two plane surfaces parallel to each other and to the axis of the projectile, the slots separating notches which are not parallel to each other are delimited by two plane surfaces which are concurrent at the level of a generatrix of the surface. cylindrical bore.

The shoe may include three pairs of notches and three main radial half-planes, the two notches constituting a pair being arranged symmetrically on either side of a main radial half-plane.

The liner may carry radial ribs arranged at its external surface and extending axially over substantially the entire length of the liner and the ribs will be angularly disposed at the level of the main radial half-planes, the set of ribs being symmetrical by with respect to any principal radial half-plane.

The shirt may include three pairs of ribs.

The initiations of ruptures may be carried out at an internal surface of the liner.

The shoe may have a knurled profile at the bottom of the throat of the belt, and the notches may extend to the knurled profile.

The invention will be better understood on reading the description which follows of particular embodiments, description made with reference to the appended drawings in which:

Figure 1 is an overall view in simplified axial section of a sub-calibrated projectile according to the invention.

FIG. 2 is a view of a first embodiment of the shoe shown alone in section along the plane B-B of FIG. 3.

Figure 3 is a top view of the same shoe.

FIG. 4 is a view of the shirt alone in section along the plane A-A of FIG. 1.

Figures 5 and 6 are top views of two alternative embodiments of the shoe.

FIG. 7 is a view of another embodiment of the shoe shown alone in section along the plane C-C of FIG. 8.

Figure 8 is a top view of the same shoe.

FIG. 9 is a view of the shirt alone associated with these last three embodiments, in section along the plane A-A of FIG. 1.

Referring to FIG. 1, a projectile 1 of the gyro-stabilized sub-calibrated type comprises a core 2, constituted by a body made of heavy material, for example tungsten, ending at the front by a ballistic warhead 3 made of alloy aluminum.

The core is disposed in a bore 14 made in a shoe 6 also made of aluminum alloy, this bore ends in a conical housing 24 on which a rear conical part of the core is supported.

The core is kept in contact with the shoe 6 by a jacket 4 made of plastic (for example nylon). Grooves, not shown, will be made on the rear face 25 of the core so as to achieve, in known manner, the rotational attachment of the shoe and the core.

The core also carries a tracer composition (not shown) arranged inside a bore (not shown) arranged at its rear part. The tracer composition is ignited by the combustion gases of the propellant charge inside the weapon, gases which reach it through an orifice 15.

The shirt is directly injected on the aluminum shoe, it carries at its front part deformable lips 11 not shown in detail and which come to press on a conical portion of the core so as to keep the latter in contact at its rear part with the sabot (which is particularly important when placing the projectile in an automatic weapon).

The lips 11 are held in abutment on the front conical part of the core by means of a wedge shape 12 secured to a false warhead 5 also made of plastic, and made integral to the liner by any means of connection , for example by ultrasonic welding.

This false warhead comprises in known manner means for ensuring its fragmentation at the outlet of the barrel of the weapon (such as primers for ruptures), and it will not be described in more detail.

The jacket has a rear zone 7 which is housed in a peripheral groove 8 of the shoe, so as to constitute a belt for sealing against propellant gases.

A knurled profile 13 is produced at the bottom of the groove 8 so as to secure the rotation of the shirt and the shoe.

The shoe 6 carries a cylindrical crown 9 whose internal cylindrical surface constitutes the bore 14, and which has a rim 10 delimiting the peripheral groove 8 on the front side of the projectile.

This rim 10 produces a substantially trapezoidal groove profile 8 which is particularly well suited for maintaining a projectile belt.

Referring to Figures 2 and 3 we note that the cylindrical crown 9 carries four notches 16, regularly distributed angularly, and separated by four slots 21. These notches extend axially to the groove 8, and preferably will not start not the knurled profile 13 so as not to weaken the rotational connection means of the shoe and the shirt.

The bottom profile of the notches 16 is here cylindrical for convenience of production (milling), but any other notch bottom profile would be possible.

Each notch 16 is delimited by two flat surfaces 18 parallel to each other and to the axis 19 of the projectile, but the flat surfaces could also be concurrent as will be explained below.

The jacket 4 being injected on the shoe 6, it has a profile complementary to the latter and it therefore penetrates inside the notches 16.

The advantage of such a configuration is that it makes it possible to dissociate the functionalities of the front part of the shirt (core retention) from that of the rear part constituting the belt. The rim 10 makes a separation between the front part and the belt part of the shirt, thus the holding of the belt is improved. The cohesion of the entire jacket is ensured by the presence of the material constituting the latter inside the notches 16.

The invention thus provides a synthesis of the advantages presented by the configuration in which the projectile has a belt separate from the shirt (holding the belt), and by that in which the projectile has a monobloc shirt (convenience of manufacture and possibility of making a shoe of reduced dimensions).

The invention also makes it possible to avoid the drawbacks attached to the one-piece structure (possibility of propagation of ruptures between front and rear parts of the shirt).

The projectile also includes means ensuring the separation of the jacket into several sectors at the outlet of the barrel, this in order to release the nucleus without disturbing its trajectory.

Referring to FIG. 4, these means comprise incipient fractures 20 (also visible in FIG. 1) produced in the form of thinning of the thickness of the jacket.

They are arranged at an internal cylindrical surface of the jacket 4 in order to simplify the design of the injection mold, and they extend axially from the slots 21 over substantially the entire length of the jacket 4.

The initiations of ruptures starting from the slots, the risk of seeing a crack at the level of the latter propagating up to the waist and causing a gas leak is avoided.

In the case of this first embodiment of the invention, there are on the jacket four breaking initiators 20 regularly distributed angularly.

These rupture primers define half-planes, hereinafter called rupture half-planes 26, which are the half-planes containing the axis 19 of the projectile and a rupture initiator 20 and limited by the axis 19 of the projectile.

The half-planes of ruptures 26, in turn determine half-planes, hereinafter called main radial half-planes 17, which are the internal bisecting half-planes of the dihedrons formed by two adjacent half-planes of ruptures 26, these main half-planes are also limited by the axis 19 of the projectile.

The half-planes of ruptures being the same number as the primers of ruptures, there will be as many main half-planes 17 as primers of ruptures and the main half-planes will be regularly distributed angularly.

The jacket portions between the fracture primers will constitute the sectors 27 which will be ejected by centrifugal force at the outlet of the weapon.

The jacket 4 also carries radial ribs 23, disposed at its external surface and extending axially over substantially the entire length of the jacket 4.

These ribs 23 are arranged angularly at the level of the main radial half-planes 17, the set of ribs being symmetrical with respect to any main radial half-plane.

These ribs have the effect of stiffening the jacket, and of guiding the projectile in the barrel of the weapon.

They also constitute weights arranged at the level of the main half-planes.

The consequence of such an arrangement is to increase the centrifugal forces exerted on the jacket at the level of these main half-planes when the projectile leaves the weapon, thereby promoting the fragmentation of the jacket 4 along the breaking points 20.

Referring to FIG. 3 in which the traces of main half-planes 17 appear, it is noted that all of the notches are symmetrical with respect to any main radial half-plane 17.

The main half-planes pass through the notches 18, and the angular position of the fracture primers 20 of the jacket, is given in this FIG. 3 by the trace of a generator 22 of the internal cylindrical surface of the bore 14 of the shoe. 6.

The flat surfaces 18 delimiting the notches being parallel to each other and to the main half-plane 17 which is associated with them, the ejection of the sectors 27 takes place without excessive resistance and in a symmetrical manner which ensures correct release of the core.

Because of the different symmetries adopted to make the shoe and the shirt, the latter will be divided into four identical sectors whose respective centers of gravity will be (in projection in the plane of Figure 3) at the notches 16, the main half-planes 17 therefore materialize the directions of the results of the centrifugal forces exerted on the different sectors 27.

The flat surfaces 18 delimiting the notches being parallel to the associated main half-planes 17, the jacket material 4 contained in the notches 16 will not prevent the ejection of the sectors 27.

We have seen previously that the notches 16 had to extend at least as far as the belt groove 8 without entering the knurled profile 13.

During the fragmentation of the jacket 4, the sectors 27 will deviate radially from each other by sliding on the flat surfaces 18 delimiting the notches, these surfaces, extending in the groove 8 of the belt until knurling 13, will constitute fracture primers for the latter thus facilitating the complete separation of the sectors of the jacket and the release of the core.

FIG. 5 represents an alternative embodiment in which the shoe 6 carries three notches 16.

In such a configuration, the projectile has three main half-planes 17, at 120 ° from one another, and the jacket also carries three initiations of ruptures whose respective angular positions are visible in FIG. 5 at the level of the generatrices 22, intersections of the cylindrical surface of the bore 14 with the rupture half-planes 26.

Figure 9 shows in section along the plane A-A of Figure 1, the jacket 4 associated with this embodiment of the invention.

This shirt carries three pairs of ribs 23, each pair being arranged symmetrically relative to the main plane 17 considered.

Such an arrangement makes it possible, by increasing the number of bearings of the jacket on the barrel of the weapon, to improve the guiding of the projectile inside the latter without unduly reducing the value of the resultant of the centrifugal forces exerted on the sectors of the jacket.

FIG. 6 represents a variant close to the previous one but in which an attempt has been made to further reduce the mass of the shoe by widening the notches 16.

In this case, the slots 21 separating the notches 16 are delimited by half-planes 18 which are concurrent at the level of the generator 22 of the internal cylindrical surface of the bore 14.

Such an arrangement makes it possible on the one hand to increase the width of the notches therefore to increase the mechanical resistance of this region of the jacket and on the other hand to reduce the frictional forces between the core and the shoe which facilitates separation of these two elements.

FIG. 9 also shows the shirt that can be associated with this embodiment.

FIGS. 7 and 8 represent a last embodiment of the invention in which the shoe 6 carries three pairs of notches 16.

The shirt associated with this shoe is again that of FIG. 9.

The main half-planes 17 pass here at the level of intermediate slots 21a delimited by plane surfaces 18 parallel to each other and to the main half-plane 17 considered.

The two notches 16 constituting a pair are arranged symmetrically on either side of the intermediate slot 21a and of the associated main half-plane 17.

Such a variant makes it possible to lighten the shoe as much as possible without excessively reducing the circumference of the rim 10 delimiting the belt groove 8.

In all the embodiments of the invention previously described, the notches were delimited by parallel flat surfaces, which makes it possible to produce them by milling.

As has already been specified above, it would also be possible to define a shoe in which the notches are delimited by concurrent, such notches could be obtained by electro-erosion.

In this case it is necessary to adopt certain rules for defining the notches so that the separation of the different sectors of the shirt is not disturbed.

First of all, the notches will be distributed over the shoe so that all of the notches are symmetrical with respect to any main radial half-plane.

This ensures that the center of gravity of the shirt sector is in the main half-plane.

Then, in the case where the number of notches adopted is such that the main half-planes intersect the slots (such as the example in FIGS. 7 and 8), the width of the slots thus cut must not decrease in a radial direction of outside to inside of the hoof.

This makes it possible to ensure that the material of the shirt which is in the notches located on either side of the slot will not come to oppose the ejection of the sectors of the shirt.

Finally, in the case where the number of notches adopted is such that the main half-planes cut the notches (such as the examples in FIGS. 2 to 6), the width of the notches thus cut must not decrease in a radial direction of the inside to outside of the hoof.

This again to ensure the proper separation of the sectors of the shirt.

Finally, it would be possible to adopt other means ensuring the separation of the jacket into several sectors at the outlet of the barrel of the weapon.

It would for example be possible to combine primers for ruptures produced axially on the liner with one or more primers for circular ruptures arranged in the vicinity of the shoe (as shown for example in patent FR2142897). These last incipient fractures will allow the separation of the various sectors of the shirt without disturbing the release of the core, in the latter case the part of the shirt constituting the belt will remain attached to the shoe.

Claims (9)

1. Spin-stabilised subcalibre projectile (1) designed to be fired from a gun and of the type comprising a core (2) arranged in a bore (14) of a sabot (6) and a jacket (5) comprising an rear annular zone (7) housed in a corresponding groove (8) of the sabot (6) and constituting a gas seal driving band, the sabot (6) comprising, at the forward end of the projectile, a cylindrical ring (9) carrying a lip (10) bounding the driving band groove (8), the ring (9) comprising at least three slots (16), separated by lands (21), the jacket (4) comprising a profile matching the sabot (6), such that it penetrates inside these slots (16) the projectile having means for separating the jacket into several segments on leaving the gun barrel under the effect of centrifugal force, characterised in that the said slots (16) extend axially at least as far as the said driving band groove (8) and that the means ensuring separation comprise:

   - incipient ruptures (20) made in the form of thinned areas in the jacket thickness (4), the said areas extending from the lands (21) of the sabot (6) axially substantially over the whole length of the jacket (4) and arranged at regular angles, all these so-called rupture half-planes (26) which are defined as the half-planes passing through the axis (19) of the projectile and containing an incipient rupture (20), also defining half-planes known as principal radial half-planes (17) which are the half-planes that internally bisect the failure half-planes (26),

   - an arrangement of slots (16) such that all the slots are symmetrical about any principal radial half-plane (17) and, secondly, in the case where the principal half-planes (17) intersect the lands (21), the width of the said lands thus intersected does not decrease radially from the outside to the inside of the sabot (6) and in the case where the principal half-planes (17) intersect the slots (16), the width of the said intersected slots does not decrease radially from the inside to the outside of the sabot (6).
2. Projectile according to claim 1, characterised in that each slot (16) is bounded by two plane surfaces (18) parallel to one another and to the axis (19) of the projectile.
3. Projectile according to claim 2, characterised in that the lands (21) separating the slots (16) not parallel to one another are bounded by two plane surfaces that intersect at a generator (22) of the cylindrical surface of the bore (14).
4. Projectile according to either of claims 2 or 3, characterised in that the sabot has three pairs of slots (16) and three principal radial half-planes (17), the two slots (16) constituting one pair being arranged symmetrically at either side of a principal radial half-plane.
5. Projectile according to any of claims 1 to 4, characterised in that the jacket (4) has radial ribs (23) on its external surface and extending axially over substantially the entire length of the jacket (4) and that the said ribs (23) are arranged at the angle of the principal radial half-planes (17), all the ribs (23) being symmetrical with respect to any principal radial half-plane (17).
6. Projectile according to claims 4 and 5, characterised in that the jacket (4) comprises three pairs of ribs (23).
7. Projectile according to any of claims 2 to 6, characterised in that the incipient ruptures (20) are produced on an inside surface of the jacket (4).
8. Projectile according to any of claims 1 to 7, characterised in that the sabot (6) comprises a milled profile (13) at the bottom of the driving band groove (8).
9. Projectile according to claim 8, characterised in that the slots (16) extend up to the milled profile (13).

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