EP0685059B1 - Safety device for locking a striker, and methods for fabricating such device - Google Patents

Description

The field of the present invention is that of safety devices for locking a striker for a revolving projectile rocket.

Projectiles, including medium caliber shells, are fitted with safety devices intended to prevent initiation of the pyrotechnic chain before firing and during the first tens of meters of the trajectory ballistic.

A known security device comprises a lock, by example a split ring, which immobilizes in translation the projectile striker, which is surrounded by a spring hairspring constituted by an elastic ribbon wound on himself.

Patent DE1197786 whose description covers the preamble of claim 1, describes such a security device for a medium caliber projectile rocket.

The lock consists of a band folded over it even so as to form a ring with a hexagonal profile. The ring forms a stop for a shoulder of the striker prohibiting him from coming to strike a primer.

Due to its split structure, the lock is susceptible to open by the action of the centrifugal force which is exerted on him when fired. Opening the lock allows the translation of the striker for example at impact on a target.

A spiral spring is wrapped around the lock. The function of the spiral spring is to delay the moment opening the lock. This opening only occurring only after a few tens of meters of trajectory which ensures the safety of the weapon's servants.

The centrifugal force exerted on the spring during firing thus causes its progressive unfolding and its winding against the wall of a cylindrical housing of the rocket. Once the spring is fully unwound, the latch can open in turn and release the striker.

Such a device has drawbacks. So we was able to observe priming faults due to the fact that the spring can form stray loops that come interfere with the striker and prevent it from translate freely.

It is the object of the invention to propose a security device not having such disadvantages.

The safety device according to the invention ensures that, when fired, the spiral spring remains correctly wound against its cylindrical housing without coming to form stray loops that could prevent the striker from coming initiate the primer.

Thus, the subject of the invention is a device for safety device intended to lock a striker for a rocket of a revolving projectile, comprising a spiral spring constituted by an elastic ribbon wound on itself and recalled by its elasticity around an organ of lock that keeps the striker in position security, the locking member being constituted by a flexible band wrapped around the striker and the material or the geometry are such that it does not exercise elastic return force towards the striker, characterized in that the strip has a length such that, when it is found during the firing carried out following the spiral spring and applied against it by the action of centrifugal force, its ends overlap.

According to one embodiment of the invention, the strip flexible has grooves, which are preferably oriented towards the striker.

The striker may be cylindrical or have a polygonal section, preferably hexagonal.

The grooves may have a variable pitch authorizing a winding of the strip on the striker following a polygonal figure.

In the case where the striker has a polygonal section, the grooves of the strip will be positioned when winding opposite the vertices of the polygon.

According to another characteristic of the invention, the strip is such that, once unrolled following the spring spiral, its ends overlap on a bow included between 60 ° and 180 °.

The invention also relates to a method of manufacturing such a device, process characterized in that it includes a step of making the grooves in the strip by knurling a smooth strip between a wheel and a counter pulley.

Knurling can be performed with a pitch wheel variable.

Alternatively, the strip can be driven between the wheel and the counter pulley by the rotation of an axis polygonal on which the knurled strip is wound, this axis polygonal being formed by the striker.

• la figure 1 est une vue schématique en coupe axiale d'un dispositif de sécurité selon un premier mode de réalisation de l'invention, dispositif représenté en position de sécurité,
• la figure 2 est une vue en coupe transversale de ce dispositif selon un plan dont la trace est repérée par la ligne AA sur la figure 1,
• la figure 3 est une vue analogue à celle de la figure 2, le dispositif étant représenté en position déverrouillée,
• la figure 4 représente en coupe transversale et en position de sécurité une variante de réalisation du dispositif selon l'invention,
• la figure 5 représente cette variante de réalisation, le dispositif étant montré en position déverrouillée,
• la figure 6 est une vue en coupe transversale et en position de sécurité d'un deuxième mode de réalisation de l'invention,
• la figure 7 schématise une étape de fabrication de la bande souple utilisée dans le premier mode de réalisation de l'invention,
• la figure 8 schématise une étape de fabrication de la bande souple utilisée dans le deuxième mode de réalisation de l'invention.

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

• FIG. 1 is a schematic view in axial section of a safety device according to a first embodiment of the invention, device shown in the safety position,
• FIG. 2 is a cross-sectional view of this device according to a plane, the trace of which is identified by the line AA in FIG. 1,
• FIG. 3 is a view similar to that of FIG. 2, the device being shown in the unlocked position,
• FIG. 4 shows in cross section and in the safety position an alternative embodiment of the device according to the invention,
• FIG. 5 represents this alternative embodiment, the device being shown in the unlocked position,
• FIG. 6 is a view in cross section and in the safety position of a second embodiment of the invention,
• FIG. 7 shows schematically a step of manufacturing the flexible strip used in the first embodiment of the invention,
• Figure 8 shows schematically a step of manufacturing the flexible strip used in the second embodiment of the invention.

Referring to Figures 1 and 2, a device for safety 1 according to a first embodiment of the invention is intended to lock a striker 2 in a safe position in which he cannot come strike a primer (not shown).

The safety device includes a cylindrical housing 3 closed by a cover 4 which is fixed to the housing by example by screws (not shown).

The housing delimits a cylindrical internal housing 14.

The case is intended to be placed in a rocket of a projectile (not shown). It will attach to the rocket at by means of an external thread 5.

The housing 3 is pierced with a hole 6 intended to authorize the passage of the tip 2a of the striker 2 to allow the percussion of the primer. The cover has a bore 7 by which the striker 2 enters the housing 3.

The striker 2 has a shoulder 8 which comes in support on a locking member 9. As is more particularly visible in Figure 2, the locking device 9 consists of a wound flexible strip in a spiral around a rod 2b secured to the striker 2. The strip 9 has grooves 10 parallel to each other and to axis 11 of the device.

Band 9 can be made of brass, copper Berylium, stainless steel or not, nickel, or in reinforced plastic or not. The choice of material will be done according to the desired stiffness for the maintaining the striker 2 and the amplitude of the centrifugal forces developed during the firing for the projectile considered.

The function of the grooves 10 is to give a some flexibility to the strip 9, allowing it to be wound up around the rod 2b of the striker 2 and facilitating its unfolding using a minimum of energy.

It is thus possible to define a locking member both very resistant (due to the thickness large band) and very flexible thanks to the presence grooves.

The band will also be defined so that it does not exert an elastic return effort towards the striker both in its rolled-up position shown in Figures 1 and 2 only when it takes place after the shooting, as this will be described later.

The strip 9 is kept in the locking position of the striker by a spiral spring 12 of known type.

This spring is formed by an elastic brass ribbon, wound on itself, and kept wound on the strip 9 by its own elasticity. Other materials could be used to make the balance spring: Nickel, stainless steel, Copper / Berylium ... An elastic clip 13 made of steel or brass keeps the spiral spring 12 in its position safety shown in Figures 1 and 2, which prohibits any untimely unwinding of the hairspring when the projectile is subjected to vibrations, for example during phases transport.

In the embodiment described here, the band 9 is wound on the rod 2b of the striker 2 so that the grooves 10 are oriented outward i.e. towards the spiral spring 12.

Such an arrangement facilitates the winding of the strip on the striker, indeed it is then the smooth face of the strip which is in contact with the striker rod.

In a known manner, at the time of the firing of the ammunition, the centrifugal inertial force first causes the opening clip 13, which is pressed against the cylindrical surface internal 15 of housing 14.

The spiral spring 12 then proceeds progressively and is wound in a spiral against the cylindrical surface internal 15.

After complete completion of the spiral spring 12, the strip 9 takes place in turn and comes to wrap against the spiral spring.

The unwinding of the tape is facilitated by the presence grooves that give flexibility even to a strip relatively thick.

The device is then in the unlocked position shown in Figure 3.

The diameter of the striker shoulder 8 is shown by circle 16 in broken lines. We thus see that the band 9 and hairspring 12 present in the unlocked position a winding diameter which is greater than the diameter of the shoulder 8. The striker rod 2 is therefore free to translate into hole 6.

Figure 3 also shows that the strip 9 has a length such that in the unlocked position its ends 9a and 9b partially overlap on a corner arc at center α.

This essential characteristic of the invention ensures that the spiral spring 12 is held on an arc of 360 ° by the unrolled strip 9.

This avoids the formation of parasitic loops on the spiral spring 12. The formation of such loops is usually caused by friction on the spring hairspring of a lock of the type described by DE1197786.

Thanks to the invention, the covering of the ends of the band maintains the spring with effort substantially equal centrifugal in all directions radial. There is therefore no relative shift of the band and spring and no loops parasites.

Band 9 can be given a length such that the overlapping arc has an angle at the center between 60 ° and 180 °, the preferred angle being of the order of 120 °.

A strip end 9 is shown in dotted lines 17 giving a 180 ° overlap.

Because the band exerts no recall effort elastic towards the striker in the unrolled position, it does not does not itself present parasitic curvature to its extremities.

The band exerting no elastic return effort towards the striker in the rolled position, so it can rotate freely on the striker which facilitates the progress of the spiral and allows to define a rocket whose striker is fixed in rotation.

Figures 4 and 5 show an alternative embodiment which does not differ from the mode described with reference to FIGS. 2 and 3 as by the orientation of the strip 9.

In this variant the strip 9 is wound on the rod 2b of striker 2 with its grooves 10 oriented towards inside ie towards the striker.

Such an arrangement improves the contact between the strip and the spiral spring when the band wraps around it during the shooting. Indeed it is then the smooth face of the strip 9 which comes into contact with the spiral spring. We thus ensures better retention of the spiral spring against the internal cylindrical surface 15.

As a variant it is possible to define a band not having splines. We will choose the material of so as to obtain a strip exerting no recall effort elastic towards the striker but having however a certain rigidity in the direction of axis 11 of the device, to ensure the locking of the striker.

We could for example define a brass band 0.4mm thick.

The material of the strip can advantageously be chosen as it undergoes by the action of centrifugal force plastic deformation allowing it to remain in the unlocking position shown in Figures 3 and 5.

Figure 6 shows in cross section and position security a second embodiment of the invention.

In this embodiment, the rod 2b of the striker 2 a a hexagonal section. Band 9 has grooves 10 which are oriented inward, i.e. towards the rod 2b of the striker, and which are arranged opposite the edges of the hexagon.

The different grooves 10 are produced on the strip 9 with a variable pitch which allows the winding of the band 9 around the rod 2b.

Thus the pitch of the grooves is constant for the six first grooves which allows the winding of a first layer of tape around the six sides of the rod of the striker. Then the pitch increases for the six grooves following values proportional to the thickness of the strip 9, thus authorizing the winding of a second layer of strip 9 around the hexagon formed by the first layer. The step then increases for the layers following.

The total length of the strip is chosen as above so as to ensure overlapping of its ends when following the shot it is wound on the spiral spring by the action of centrifugal force.

Such an embodiment allows like the previous one ensure good retention of the spiral spring due to the contact of the smooth face of the strip on this one.

It also ensures good winding of the strip on the striker rod and a fastening angular of these two elements which improves the holding of the vibration device.

In this case, however, the striker will be mounted free in rotation in the rocket so as to facilitate the unwinding hairspring.

A good winding also avoids misalignments of the strip and the striker likely to cause unbalanced which affect the proper functioning of the rocket.

The hairspring is wound when the device is assembled also facilitated by the angular connection of the strip and the striker.

As an example for a 30mm caliber projectile we can adopt a 3mm wide brass band and 0.4mm thick with 0.3mm splines depth.

This strip is wound four turns on a rod of hexagonal striker (face width 1.6mm) and receives a spiral spring 1m long.

When after firing the hairspring is pressed against the wall cylindrical housing (diameter 14mm), the ends of the strip overlaps with an arc of 100 ° angle in the center.

As a variant, it is of course possible to define a polygonal section striker on which a band will be wound up, the variable pitch of the grooves will be chosen according to the number of faces of the polygon.

Figure 7 shows schematically a step of manufacturing the flexible tape which is used in the embodiments Figures 2 to 5.

The raw tape 91 is cut from a reel not represented. It goes between a knurled wheel 18 and a against pulley 19. The knurled wheel is made of steel, it is driven in the Z direction by a motor 20 and ensures both pulling the raw tape 91 and achieving on the latter grooves 10.

To this end, the wheel 18 carries teeth 21 with a profile. triangular, the length of which is greater than or equal to the width of the strip 9 and the pitch of which determines the pitch of the splines 10.

The counter pulley is freely mounted on bearings 22, the distance between the counter pulley and the knurled wheel is adjustable to adjust the depth of the grooves 10.

The counter pulley 19 has a width greater than or equal to that of the band, it is covered with rubber to promote the training of the band and avoid any relative slip.

The strip 9 on which the grooves 10 are made is then cut to the desired length using knives 23 whose known drive means are not not shown.

This embodiment also makes it possible to give the band a camber directed towards the knurled wheel, which facilitates its subsequent winding on the striker.

Figure 8 shows schematically a step of manufacturing the flexible strip which is used in the embodiment in Figure 6.

The raw strip 91 passes between the knurled wheel 18 and the against pulley 19. The knurled wheel is still driven in the Z direction by a motor 20 and ensures the traction of the strip rough 91 and making the grooves 10.

The counter pulley 19 is freely mounted on bearings 22, the distance between the counter pulley and the knurled wheel is still adjustable.

In this embodiment, the knurled wheel carries teeth 21 whose pitch is variable. She thus wears six first teeth 21a, relatively close together others and dismissed with a constant first step.

These first teeth are followed by six second teeth 21b, a little further apart from each other by a second constant step.

The second teeth are finally followed by six thirds teeth 21c, further apart from one another by third constant step.

The set of teeth 21a, 21b and 21c makes it possible to produce on the raw strip 91 grooves whose variable pitch authorizes the winding of the strip 9 on a hexagonal rod as previously described.

The strip 9 is then cut to the desired length at knife medium 23.

According to a variant of this process, it will be possible to ensure the drive of the strip 9 by means of a hexagonal axis on which the formed band will come to wind.

This hexagonal axis will preferably be constituted by the rod 2b of striker 2, rotated in the direction Z 'by a motor not shown.

It is then unnecessary to provide a drive motor of the knurled wheel.

The advantage of this process and that it makes it possible to obtain directly a striker 2 equipped with its latch strip 9 and this with a tightening determined for the winding of the strip on the striker.

It will be enough to adjust the tightening to modify the tension band 9 playing on the torque of the drive motor of the striker and on the resistant torque of the counter pulley or knurled wheel (fitted with adjustable brakes).

Claims (10)

1. Safety device intended for locking a firing pin for a spin-stabilised projectile fuse, comprising a spiral spring (12) consisting of an elastic strip wound upon itself and pulled back by its elasticity around a locking device which maintains the firing pin (2) in the safe position, the locking device consisting of a flexible strip (9) wound around the firing pin (2) and the material and geometry of which are such that it exerts no elastic return force towards the firing pin (2), characterised by the fact the strip having a length such that when during firing it is unwound following the spiral spring (12) and pressed against the said spiral spring by the action of centrifugal force, its ends (9a, 9b) overlap.
2. Device according to claim 1, characterised by the fact that the flexible strip contains grooves (10).
3. Device according to claim 2, characterised by the fact that the grooves (10) are orientated towards the firing pin (2).
4. Device according to any of the claims 1 to 3, characterised by the fact that the firing pin is cylindrical.
5. Device according to claim 3, characterised by the fact that the grooves (10) have a variable pitch allowing the strip (9) to be wound on the firing pin to give a polygonal shape.
6. Device according to claim 5, characterised by the fact that the firing pin (2b) has a polygonal section, preferably hexagonal, the grooves (10) of the strip being located as it winds on at the corners of the polygon.
7. Device according to any of the claims 1 to 6, characterised by the fact that, once the strip has unwound following the spiral spring, its ends overlap along an arc of between 60° and 180°.
8. Process for producing a device according to any of the claims 2 to 7, characterised by the fact that it comprises a stage of producing the grooves (10) in the strip by knurling a smooth strip between a knurling wheel (18) and a backing pulley (19).
9. Process according to claim 8, characterised by the fact that the knurling is done with a knurling wheel (18) of variable pitch.
10. Process according to either of the claims 8 or 9, characterised by the fact that the strip is pulled between the knurling wheel and the backing pulley by the rotation of a polygonal shaft on which the knurled strip (9) winds, this polygonal shaft consisting of the firing pin (2b).

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