EP1475601B1 - Subcalibre projectile, rod and sabot constituting such a projectile - Google Patents

Description

The technical field of the invention is that of projectiles comprising a sub-calibrated bar disposed in a caliper shoe.

The shoe is made of a lightweight material such as aluminum and, in a conventional manner, it is formed of several segments (most often three) surrounding the bar. The segments are linked together by a gastight belt in the barrel and one or two retaining rings, located at the front or rear of the shoe, or on a front guide surface.

The shoe allows the barrel to be fired by the barrel of the weapon. It releases the bar at the exit of the tube.

The bar and the shoe generally comprise profiles that cooperate with each other so as to ensure the axial drive of the bar by the hoof when firing the projectile. These profiles may include a helical thread on the bar which is housed in a tapping of the shoe or even by a succession of teeth and annular grooves.

The patent FR2666647 describes such a known projectile.

The conventional drive profiles are designed to provide the shoe with a bearing surface enabling it to transmit to the bar the longitudinal thrust force created by the action of the powder gases. This profile is therefore mainly sized to resist shearing.

The conventional profiles are either so-called ISO profiles (in which the teeth are trapezoidal and symmetrical with respect to a transverse plane) or so-called artillery profiles (in which the teeth are not symmetrical but have a strongly inclined rear flank to the axis of the bar).

When a projectile with a known type of training profile moves in the tube of a weapon, it undergoes a number of transverse perturbations which are caused by the curvature of the tube, the pressure asymmetries and the own vibrations of the projectile which generate flexions of the bar.

The three segments of the shoe then work independently and generally there is at a given moment only one or two segments to support the bar in flexion. The hoof therefore does not help the bar to resist flexion.

These movements of the segments are all the more important that the bar is of great length (elongation L / D greater than 25).

In addition, the shoe can itself, by the combined action of its inertia, pressure forces and transverse accelerations, begin to open at the front pocket. He is less supportive of the bar.

The patent US Patent 4754770 describes a sub-calibrated projectile comprising a bar and a shoe formed of several segments. The bar has a cylindrical belt provided with a bead of circular section. The shoe has a profile complementary to the bead so that each segment can rotate around the bead. The belt also has teeth whose rear face has a semi-circular section profile cooperating with a complementary profile of the shoe to ensure the rotation of the segments of the latter. Such a projectile is of complex realization, moreover it does not solve the previously mentioned problem of the opening of the hoof during firing of the projectile.

The patent US 3859922 describes the preamble of claim 1.

The defects of maintenance of the bar lead to obliquities of shooting and a loss of precision.

Moreover, during this opening of the front of the shoe, the guide surfaces rub more strongly on the tube, which increases the wear thereof.

It is the object of the invention to provide a projectile to overcome such drawbacks. The invention also for object the bar and the shoe constituting such a projectile.

Thus the projectile according to the invention comprises means at the drive interface of the bar by the shoe which also provide a radial maintenance of the segments of the shoe.

This results in a better rigidity in bending of the shoe and a better maintenance of the bar, thus an improvement in the accuracy of the shot. This increase in transverse stiffness also makes it possible to reduce the mass of the hoof.

Thus, the subject of the invention is a sub-calibrated projectile comprising a bar and a shoe formed of several segments, the bar and the shoe comprising profiles cooperating with each other so as to ensure the axial drive of the bar by the sabot during firing of the projectile, characterized in that it has an axial clearance between the profile carried by the shoe and that carried by the bar so as to allow a limited relative axial displacement of the shoe relative to the bar, and in that that the bar comprises at least one tooth whose rear face has a concave conical profile cooperating during firing with a convex conical profile formed on a front face of at least one tooth carried by the shoe in order to ensure radial locking of the segments the shoe by the bar in a forward position of the shoe relative to the bar, this locking being no longer ensured in a rear position of the shoe relative to the bar.

According to one embodiment of the invention, the profiles carried by the shoe and the bar are in the form of teeth separated by grooves, teeth and grooves being annular or formed by a helical thread, these profiles constituting the teeth ensuring radial locking. segments of the hoof relative to the bar during firing.

According to one embodiment, a front face of the teeth carried by the bar has a convex conical profile disposed during the firing distance of a concave conical profile formed on a rear face of the teeth carried by the shoe, these profiles also coming from contact with each other at the output of the weapon tube when the shoe back relative to the bar, the contact between these profiles to move the bar segments of the shoe.

According to another embodiment, a front face of the teeth carried by the bar has a concave profile disposed during the distance firing of a convex profile made on a rear face of the teeth carried by the shoe, these profiles also coming into contact with each other at the exit of the barrel of the weapon during the retreat of the shoe relative to the bar, the shapes of the profiles being chosen to separate the segments of the shoe from the bar with an initial movement of the segments substantially parallel to the bar.

According to another embodiment, the locking means comprise a specific tooth located in front of the grooves or the thread of the bar, tooth having at its rear face a concave conical profile cooperating during firing with a convex conical profile made on a front face of a tooth carried by the shoe so as to ensure a radial locking of the shoe segments relative to the bar during firing.

The invention also relates to a sub-calibrated bar intended to be incorporated in a projectile and characterized in that it comprises an external profile comprising teeth separated by grooves, teeth and grooves being annular or formed by a helical thread, a rear side of the teeth having a concave conical profile.

A front face of the teeth of the bar may have a convex conical profile

Alternatively, a front face of the bar teeth may have a concave profile.

The bar may comprise an external profile comprising teeth separated by grooves, teeth and grooves being annular or formed by a helical thread, a specific tooth being disposed forward teeth or grooves of the bar, tooth having a concave conical profile at the level of its back side.

The invention also relates to a shoe intended to be incorporated in a projectile, shoe characterized in that it comprises an inner profile for receiving a bar and having teeth separated by grooves, teeth and grooves being annular or formed by a helical thread, a front face of the teeth having a convex conical profile.

A rear face of the hoof teeth may have a concave conical profile

Alternatively, a rear face of the hoof teeth may have a convex profile.

The shoe may include an internal profile for receiving a bar and having teeth separated by grooves, teeth and grooves being annular or formed by a helical thread, the front face of the tooth arranged the most forward having a convex conical profile.

• la figure 1 représente en coupe longitudinale schématique un sabot d'un projectile flèche selon l'art antérieur ou selon l'invention,
• les figures 2a et 2b montrent de façon agrandie des profils de liaison selon l'art antérieur, la figure 2a montrant un profil ISO et la figure 2b un profil artillerie,
• la figure 3a montre de façon agrandie un premier mode de réalisation d'un profil d'entraînement mis en oeuvre sur un projectile selon l'invention, cette figure montre la coopération du profil du sabot avec celui du barreau lors du tir du projectile,
• la figure 3b montre la coopération du profil du sabot avec celui du barreau à la sortie du tube de l'arme,
• la figure 4a montre de façon agrandie un deuxième mode de réalisation d'un profil d'entraînement mis en oeuvre sur un projectile selon l'invention, cette figure montre la coopération du profil du sabot avec celui du barreau lors du tir du projectile,
• la figure 4b montre une première étape de la coopération du profil du sabot avec celui du barreau à la sortie du tube de l'arme,
• la figure 4c montre une deuxième étape de la coopération du profil du sabot avec celui du barreau à la sortie du tube de l'arme,
• la figure 5a montre de façon agrandie un autre mode de réalisation d'un profil d'entraînement mis en oeuvre sur un projectile selon l'invention, cette figure montre la coopération du profil du sabot avec celui du barreau lors du tir du projectile,
• la figure 5b montre la coopération du profil du sabot avec celui du barreau à la sortie du tube de l'arme.

The invention will be better understood on reading the following description of various embodiments, a description given with reference to the appended drawings and in which:

• the figure 1 is a diagrammatic longitudinal section of a sabot of an arrow projectile according to the prior art or according to the invention,
• the Figures 2a and 2b show, in an enlarged manner, connection profiles according to the prior art, the figure 2a showing an ISO profile and the figure 2b an artillery profile,
• the figure 3a shows enlargedly a first embodiment of a driving profile implemented on a projectile according to the invention, this figure shows the cooperation of the profile of the shoe with that of the bar when firing the projectile,
• the figure 3b shows the cooperation of the profile of the shoe with that of the bar at the exit of the tube of the weapon,
• the figure 4a shows enlargedly a second embodiment of a driving profile implemented on a projectile according to the invention, this figure shows the cooperation of the profile of the shoe with that of the bar when firing the projectile,
• the figure 4b shows a first step of the cooperation of the profile of the shoe with that of the bar at the exit of the tube of the weapon,
• the figure 4c shows a second step of the cooperation of the profile of the shoe with that of the bar at the exit of the tube of the weapon,
• the figure 5a shows enlargedly another embodiment of a driving profile implemented on a projectile according to the invention, this figure shows the cooperation of the profile of the shoe with that of the bar when firing the projectile,
• the figure 5b shows the cooperation of the profile of the shoe with that of the bar at the exit of the tube of the weapon.

Referring to the figure 1 , a projectile 1 according to the invention or according to the prior art comprises in a conventional manner a bar 2 and a shoe 3 formed of several segments.

The bar carries a empennage 4 at its rear part and the various segments of the shoe are secured to each other by a belt 5 and a front ring 6.

The bar 2 is housed in a bore 7 of the shoe 3. This bore has a profile (not visible on the figure 1 ) which cooperates with a profile carried by the outer cylindrical surface of the bar 2 so as to ensure the axial drive of the bar by the shoe during firing of the projectile. The oval zone marked Z on the figure 1 is enlarged on the Figures 2a to 4c zone Z1 is also enlarged on the Figures 5a and 5b these zones make it possible to highlight the differences between the bonding profiles for the projectiles according to the prior art and for the projectiles according to the invention.

The Figures 2a and 2b show in an enlarged manner and in longitudinal section Z zone for binding profiles according to the prior art.

These profiles comprise a succession of teeth separated by grooves. The hoof teeth are marked D3 and the grooves of the shoe G3, the teeth of the bar are marked D2 and the grooves of the bar G2.

For the ISO profile represented at figure 2a , the teeth D2, D3 and the grooves G2 and G3 are in the form of trapeziums, all symmetrical with respect to a plane perpendicular to the axis of the bar and passing through the middle of the vertex of the tooth or throat considered .

Thus, the front and rear flanks 9 of each tooth (or groove) form an angle equal to the direction of the bore 7.

The figure 2b shows another known training profile, the artillery profile. In this profile the teeth and grooves are not symmetrical. In particular, the teeth D2 of the bar comprise a rear flank 9 which is strongly inclined with respect to the direction of the bore 7.

The known profiles are either constituted by a helical thread on the bar cooperating with a tapping on the shoe, or by a succession of teeth and annular grooves.

The Figures 3a and 3b show in an enlarged way the Z zone of the figure 1 for a projectile according to a first embodiment of the invention.

According to this mode, each rear face 11 of the teeth D2 carried by the bar 2 has a concave conical profile which is defined so as to cooperate during firing with a convex conical profile formed on each front face 12 of the teeth D3 carried by the shoe 3.

This cooperation ensures a radial locking of the segments of the shoe 3 relative to the bar 2 during firing.

Thus the segments are no longer separated from the bar inside the tube and maintain the latter by reducing bending.

Due to the orientation of the conical faces (11,12) of locking, the maintenance of the segments of the shoe 3 is even more rigid that the propulsive force is stronger. The Locking of the hoof segments improves the cohesion of the projectile. The entire hoof can then work in flexion which can help lighten the hoof. In fact it is thus possible to reduce hoof thicknesses which would have been partly chosen to increase the resistance to bending. This relief can be of the order of about 5%.

The half-angle at the top α ( figure 3b ) conical surfaces of the faces 11 and 12 will be chosen from about 70 ° to 85 °.

The longitudinal clearance J will be chosen taking into account the drifts on the machining tolerances of the teeth (or the threading) as well as taking into account the maximum possible thermal expansions.

This clearance allows a limited relative axial displacement of the shoe 3 relative to the bar 2.

Such an arrangement is intended to allow the separation of the shoe and the bar at the exit of the barrel of the weapon.

The operation of this projectile is as follows.

When shooting the pressure exerted on the rear of the shoe causes it to the front. There is therefore a relative displacement of the shoe with respect to the bar according to the arrow F (see figure 3a ). This displacement brings the conical profile of the front face 12 of the teeth D3 of the shoe in contact with the complementary profile of the rear face 11 of the teeth of the bar.

There is then radial locking of the segments of the shoe 3 around the bar 2. This locking is ensured as long as the pressure of the gases acts on the back of the shoe, ie during the entire path of the projectile inside. of the weapon tube.

At the exit of the tube of the weapon, the pressure exerted on the back of the hoof drops abruptly. Moreover the relative wind created by the displacement of the projectile in the air tends to oppose the displacement of the hoof. The shoe 3 then moves with respect to the bar 2 towards the rear along the arrow F '(see figure 3b ).

This movement ensures the unlocking of the shoe-bar connection. The shoe 3 thus released can separate from the bar 2 according to the conventional opening mechanisms.

Each front face 13 of the teeth D2 carried by the bar 2 has a convex conical profile which comes into contact during the retreat of the shoe with a concave conical profile formed on each rear face 14 of the teeth D3 carried by the shoe 3.

The cooperation of these conical profiles ensures, together with the axial displacement, a radial relative displacement of the segments of the shoe 3 with respect to the bar 4. To facilitate this separation, the half-angle at the vertex β ( fig 3b ) cones of the faces 13 and 14 will be of the order of 45 ° to 60 °.

The machining of the profiles will be easily achieved using a tool having a shape corresponding to the shape of the groove to be machined.

The Figures 4a, 4b and 4c show in an enlarged way the Z zone of the figure 1 for a projectile according to a second embodiment of the invention.

Again, the teeth D2 and D3 carried by the bar or shoe have faces 11 and 12 which cooperate to ensure a radial locking of the shoe segments relative to the bar when firing the projectile (movement of the shoe forward by compared to the bar, according to the arrow F shown in figure 4a ).

According to this particular embodiment each front face 13 of the teeth D2 carried by the bar 2 has a concave profile which is intended to cooperate at the exit of the barrel of the weapon with a convex profile carried by each rear face 14 of the teeth D3 worn by the hoof 3.

Moreover, these profiles have a shape that is chosen so as to favor during the separation shoe / bar a radial spacing of the segments of the shoe.

Such an arrangement makes it possible to favor a shoe / bar separation with an initial movement of the segments substantially parallel to the bar. This minimizes the disturbances or shocks brought to the bar by the shoe during the opening of the latter.

In order thus to favor the radial displacement of the segments of the shoe, the profile of the front face 13 of the teeth D2 of the bar will be defined so that the tangent T to this profile ( figure 4b ) is close to a radial direction at the bar 2 (angle γ of the tangent T with a radial plane 10 of the order of 5 ° to 10 °).

Again the profiles are easily machined using a tool having a shape corresponding to the shape of the groove to be machined.

The Figures 5a and 5b show in an enlarged way the zone Z1 of the figure 1 , zone disposed at the front portion of a projectile according to a third embodiment of the invention.

In this particular embodiment, the teeth D2, D3 and the grooves G2, G3 of the bar and the shoe have a conventional ISO profile similar to that described previously with reference to FIG. figure 2a (but they could also have an artillery profile like those of the figure 2b ). The profile may be constituted either by a thread or by a succession of teeth and annular grooves.

According to the invention a clearance J is still provided allowing an axial displacement of the bar 2 relative to the shoe 3.

According to this particular embodiment, a specific tooth 15 is located in front of the grooves G2 and teeth D2 of the bar 2. This tooth comprises at its rear face 16 a concave conical profile cooperating during the firing. with a convex conical profile 17 formed on a front face of a tooth 18 carried by the shoe 3.

The half-angle at the top α ( figure 5b ) conical surfaces of the faces 16 and 17 will be chosen of the order of 70 ° to 85 °. This cooperation of the profiles at the level of the tooth 15 makes it possible to ensure radial locking of the segments of the shoe 3 with respect to the bar 2 during firing.

The operation is similar to that described for the previous embodiments. When firing the pressure exerted on the back of the shoe 3 pushes it forward. There is relative displacement of the shoe with respect to the bar according to the arrow F ( figure 5a ) and locking the tooth 18 by the tooth 15.

Unlike other embodiments, only the front portion of the shoe 3 is locked here. It can not deviate from the bar during the gun phase despite the effects of acceleration and air pressure. The bar is well maintained and it also avoids premature wear of the guide lands 6 which would be consecutive to a spacing of the segments of the shoe 3.

Locking is ensured as long as the pressure of the gases acts on the rear of the shoe, ie during the entire course of the projectile in the barrel of the weapon.

At the outlet of the tube, the pressure exerted on the back of the hoof drops sharply. The shoe, pushed by the relative wind created by the flight of the projectile, moves relative to the bar rearward along the arrow F '( figure 5b ).

This movement ensures the unlocking of the bar shoe connection. The released shoe can separate from the bar following the usual opening mechanisms.

Claims (13)

1. A sub-calibre projectile (1) incorporating a penetrator (2) and a sabot (3) formed of several segments, the penetrator (2) and sabot (3) incorporating profiles that cooperate with one another so as to ensure the axial drive of the penetrator (2) by the sabot (3) when the projectile is being fired, such projectile being characterised in that there is axial play (J) between the profile on the sabot (3) and that on the penetrator (2) so as to enable a limited relative axial displacement of the sabot with respect to the penetrator, and in that the penetrator (2) comprises at least one tooth (D2, 15) which rear face (11, 16) is provided with a conical concave profile cooperating during firing with a convex conical profile made on a front face (12, 17) of at least one tooth (D3, 18) on the sabot (3), in order to ensure a radial locking of the sabot segments by the penetrator (2) in a forward position of the sabot with respect to the penetrator, this locking being no longer ensured in a rear position of the sabot with respect to the penetrator.
2. A sub-calibre projectile according to Claim 1, wherein the profiles on the sabot (3) and on the penetrator (2) are formed of teeth (D2, D3) separated by grooves (G2, G3), the teeth and grooves being ring-shaped or formed by helicoidal threading, these profiles constituting the teeth to ensure a radial locking of the sabot (3) segments with respect to the penetrator (2) during firing.
3. A sub-calibre projectile according to Claim 2, wherein a front face (13) of the teeth (D2) on the penetrator (2) has a convex conical profile arranged during firing at a distance from a concave conical profile made on a rear face (14) of the teeth (D3) on the sabot (3), these profiles being additionally in contact with one another upon exiting the gun barrel when the sabot (3) recoils with respect to the penetrator (2), the contact between these profiles enabling the sabot (3) segments to be kept away from the penetrator (2).
4. A sub-calibre projectile according to Claim 2, wherein a front face (13) of the teeth (D2) on the penetrator (2) has a concave profile arranged during firing at a distance from a convex profile made on a rear face (14) of the teeth (D3) on the sabot (3), these profiles coming into contact with each other upon exiting the gun barrel when the sabot (3) recoils with respect to the penetrator (2), the shape of the profiles being chosen so as to keep the sabot (3) segments away from the penetrator (2) with a starting movement of the segments that is substantially parallel to the penetrator (2).
5. A sub-calibre projectile according to Claim 1, wherein the locking means comprise a specific tooth (15) located to the fore of the grooves or threading on the penetrator (2), such tooth incorporating a concave conical profile on its rear face (16) cooperating during firing with a convex conical profile made on a front face (17) of a tooth (18) on the sabot (3) so as to ensure the radial locking of the sabot (3) segments with respect to the penetrator (2) during firing.
6. A sub-calibre penetrator (2) intended to be incorporated into a projectile (1) according to one of Claims 1 to 4, wherein it incorporates an external profile incorporating teeth (D2) separated by grooves (G2), teeth and grooves being ring-shaped or formed by helicoidal threading, a rear face (11) of the teeth (D2) having a concave conical profile.
7. A sub-calibre penetrator according to Claim 6, wherein a front face (13) of its teeth (D2) has a convex conical profile.
8. A sub-calibre penetrator according to Claim 6, wherein a front face (13) of its teeth has a concave profile.
9. A sub-calibre penetrator (2) intended to be incorporated into a projectile (1) according to Claim 5, wherein the penetrator (2) incorporates an external profile incorporating teeth (D2) separated by grooves (G2), teeth and grooves being ring-shaped or formed by helicoidal threading, one specific tooth (15) being positioned to the fore of the teeth or grooves of the penetrator, such tooth incorporating a concave conical profile at its rear face (16).
10. A sabot (3) intended to be incorporated into a projectile (1) according to one of Claims 1 to 4, wherein it incorporates an internal profile intended to accommodate a penetrator (2) and incorporating teeth (D3) separated by grooves (G3), teeth and grooves being ring-shaped or formed by helicoidal threading, one front face (12) of the teeth (D3) having a convex conical profile.
11. A sabot according to Claim 10, wherein a rear face (14) of its teeth (D3) has a concave conical profile.
12. A sabot according to Claim 10, wherein a rear face (14) of its teeth (D3) has a convex profile.
13. A sabot (3) intended to be incorporated into a projectile (1) according to Claim 5, wherein it incorporates an internal profile intended to accommodate a penetrator (2) incorporating teeth (D3) separated by grooves (G3), teeth and grooves being ring-shaped or formed by helicoidal threading, the front face (17) of the tooth (18) positioned the foremost incorporating a convex conical profile.

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