FR2664040A1 - DEVICE FOR SECURING AND ARMING MILITARY LOADS. - Google Patents

Abstract

The object of the invention is a safety and arming device for ammunition, capable of ensuring the alignment of the pyrotechnic chain and being able to occupy two different positions, a first in which the firing of the ammunition is prohibited and a second in which the firing is transmitted. It consists of a chain interruption means 3 comprising a passage 2a formed along a diameter perpendicular to the directions of the stresses undergone by the ammunition during the operational phases, whether or not integrating a relay composition 2 actuated along a helical angle trajectory. a to bring the passage 2a from the first so-called safety position in which it is located in a plane substantially orthogonal to the axis of alignment of the pyrotechnic chain, into the second so-called cocking position where it is aligned with the axis 6 of the chain. The helical movement is the combination of a translational movement and a rotational movement of about 90 degrees and is carried out in three successive phases, a first phase A during which we ensure above all a translational movement and a low rotation between 0 and 15% of the angle a, then in a phase B of significant rotation between about 15 and 85% of the angle a, and finally in a phase C especially a translational movement and a low rotation up to to the armed position. Application to military charges

Description

The technical sector of the present invention is that of

  security and arming a pyrotechnic chain placed between an initiation composition and a

  priming composition of the explosive charge of a munition.

  Numerous safety devices have been proposed to ensure this function Generally, a pyrotechnic flap (disk for example) is used which rotates from a safety position to an armed position. Various security systems ensure the release of the flap. the conditions of

i O shot or ignition provided.

  Thus, patent FR-A-2 463 386 describes a safety device timed by a spiral spring. However, this device is applied to a gyratory projectile and the lock describes an arc to move from the safety position to

the armed position.

  Patent FR-A-2 344 809 describes a rocket whose safety flap consists of a mobile shaft first in rotation and then in translation to move from the safety position to the armed position, the display of the armed position being

  ensured by an intermediate piece.

  The significant mechanical stresses to which arms and ammunition are subjected during the firing of the thrusters or during the impact on the sea of submarine weapons and ammunition released from aircraft, are liable to cause accidental operation and untimely weapon or ammunition. The seat of the excitation (operation) comes mainly from the armament security device (DSA) which

contains primary explosives.

  In the case of underwater ammunition dropped from aircraft, the mechanical stresses experienced by the munition or the weapon, at the impact of the sea, are important The characteristics of the stresses undergone depend on several factors: drop altitude , speed of impact on the sea, sea state, impact incidence, By definition, ammunition or underwater weapon is designed to operate at a specified immersion. Premature operation at impact shows a lack of reliability and lack of system security and engages the safety of the launching aircraft, at altitudes of

  drop, which is often the case.

  The object of the present invention is to reduce the harmful effects of these constraints and to improve the safety and the reliability of operation of the DSA, avoiding unwanted operations due to accidental events, but also premature operation due to transient alignment. of the pyrotechnic chain during major mechanical stress, the impact on the sea of weapons and ammunition

  submarines dropped from an aircraft.

  The subject of the invention is therefore a device for security and arming for ammunition, capable of ensuring the alignment of the pyrotechnic chain and which can occupy two different positions, a first in which the firing of the ammunition is prohibited and a second in which the firing is transmitted, characterized in that it consists of a chain interruption means comprising a passage made in a diameter perpendicular to the directions of the stresses sustained by the munition during the operational phases, integrating or not a relay composition, actuated along a helical path of angle α to bring the passage of the first so-called safety position in which it is located in a plane substantially orthogonal to the axis of alignment of the pyrotechnic chain, in the second so-called armament position where he

  is aligned with the axis of the chain.

  The helical movement can be the combination of a translational movement and a rotation movement of about 9 °. The helical movement of the means can be carried out in three successive phases, a first phase A in which it ensures above all a translational movement and a small rotation between 0 and 15% of the angle a, then in a phase B of significant rotation between about 15 and% of the angle a, and finally in a phase C especially a movement

  of; translation and a slight rotation to the armed position.

  The means may be constituted by a shaft placed perpendicularly to the axis of the pyrotechnic chain, the helical movement being obtained by means of a pinion assembly of

guide / helical groove.

  The helical groove can be made on the shaft

  following the profile shown in Figure 3.

  The means of interruption may be provided with means of

  viewing of both security and arming positions.

  The helical movement can be controlled by a rack-and-pinion type motor system actuating the interruption means. The helical movement can be controlled by pressure

  hydrostatic acting on the means of interruption.

  The helical movement can be controlled by borrowing gas taken from the propellant of the munition acting on

the means of interruption.

  An advantage of the present invention lies in the fact that it eliminates pinching, punching and friction phenomena of the priming explosives which are sensitive to them, since the active ingredients are placed in a position of

less stress.

  Another advantage lies in the fact that the device provides a delay, or mechanical inertia, additional to the alignment of the non-detrimental initiation chain to the system, absorbs the stresses and mechanical stresses along a preferred axis (perpendicular to the direction of the

movement of the ammunition).

  The latter is then always in contact with any smooth walls,

  during the maximum stress phase.

  Another advantage lies in the fact that the combined movement translation and especially rotation (1/4 of a turn), makes it possible to visualize in a precise and unambiguous way so the armed position of the DSA from a mark engraved at the end of the means of interruption, either directly if the axis end is visible, or by reference to the position of this marker using an optical fiber for example, and not on a part

separate extra.

  It should be noted that this control is easier and more precise on a pyrotechnic component of the "axis" type than on a component

pyrotechnic type "disk".

  The knowledge of this information (armed or unarmed) is of paramount importance regardless of the configuration

the weapon or ammunition.

  Other advantages of the present invention will be better

  understood on reading the additional description which will follow

  of an embodiment given by way of example in relation to a drawing in which: FIG. 1 is a partial section of the pyrotechnic chain, FIG. 2 is a section AA of FIG. 1 showing two types of FIG. 3 illustrates the combination of translational and rotational movements according to the invention, FIGS. 4 to 6 show three examples.

  illustration of engine systems of the tree.

  The pyrotechnic chain partially shown in FIG. 1 comprises an electric or percussion initiator 1, a relay composition 2 carried by a shaft 3 in a passage 2a, and a main detonator relay 4 which is adjacent to a conventional explosive composition, not shown. The assembly is integrated in an ammunition 5 partially shown and must be aligned in the armed position on the axis 6 of the pyrotechnic chain. The shaft 3 slides in a housing 7 of the munition according to a helical movement detailed in FIG. a force applied along the arrow X on one end thereof For this purpose, a guide pin 8 is fixed in the housing 7 and is engaged in a groove 9 formed on the shaft 3 A visualization means 3 a of the position of the shaft 3 is provided at the end; this means can be a groove made at the end of the axis along a diameter. The direction is chosen by

3, convention.

  The shaft 3 rotates about its axis of rotation 10 by an angle α, of the order of 9 Q 0, and undergoes a translation (d) to bring the passage 2a or the composition 2 in alignment with the initiator 1 and the relay 4 The shaft is locked in this position However, after an abnormal behavior in the flight or dropped phase of the ammunition, the shaft can be brought back into position

  security, either automatically or manually.

  FIG. 1, which notably relates to the concept of the pyrotechnic flap of the axis type with a helical ramp and the control of the position of the flap directly at the end of the axis, does not reveal the other characteristics of the DSA such as the return devices of the pyrotechnic flap and shutter lock in safety position (unarmed). These devices, not shown, are of simple design and can be multiple: coil springs, blade, for the return device, limited to very simple devices, flyweight, erasable stop, pin and mobile security flame, possibly shear pin

  in some cases for the blocking device.

  The positioning of these devices is indicated in the figures. In FIG. 2A, there is shown a section showing a percussive primer associated with a relay 12. FIG. 2B shows a relay tablet consisting of a capsule 13 enclosing an ignition explosive 14. The initiator is stationary and is located

  designated 1 in Figure 1.

  FIG. 3 shows an example of a groove for an underwater ammunition type projectile. According to the invention, this groove ensures a combined translational-rotating movement while allowing a progressive movement. FIG. 3 represents an example of a developed of the helical ramp, ie the variation of the angle of rotation a in function x as a function of the displacement D The respective extreme values are 9 O 'and 15 mm, but they can be modified obviously by the man of In the first half of the developed, the curve has a first portion having a radius 3 o of curvature Ri of the order of 10 mm, followed by a second portion having a radius of curvature R 2 of the order of 8 mm. Halfway through the shaft 3, the curve changes direction according to a radius R 3 of the order

  8 mm followed by a final portion of radius R 4 of about 10 mm.

  The movement of the shaft 3 is therefore according to 3 phases of rotation A, B and C whose respective final values are 12, 78 and 90 'and corresponding to the translations also

5, 10 and 15 mm respectively.

  The displacement of the shaft 3 takes place in three phases, a phase A o the shaft at the beginning of the alignment phase (maximum loads), a predominant translational movement in order to place the explosive relay along axes less mechanical stress, a phase B o ensures a predominant rotation alignment, combined with a translation alignment at the end of the impact on the sea or after, in immersion phase The rotation alignment angle can be other;

  but, it is close to 90 'in general.

  a phase C where at the end of the alignment phase a predominant translatory movement is obtained in order to reduce the mechanical inertia of the moving equipment (flap equipped with seals, friction of the guide pin in the groove and spring of reminder) and perfect the alignment of the chain

  pyrotechnic (low level alignment pressure).

  The rotational alignment angle may be quite different;

  but, it is close to 90 'in general.

  The movement of the pyrotechnic flap, represented according to the development of the helical ramp, must not have a 2 o radius of "low curvature" in order to avoid any blockage of the pyrotechnic flap (movement of the guiding pin in the groove) o the interest of the helical ramp that meets all these criteria. An interest of the helical ramp is to allow to bring almost in contact (some 1/10 mm possible), without risk of mechanical stress, two pyrotechnic elements ensuring the proper operation of the chain

pyrotechnic detonation.

  It is also possible to vary the pitch of the ramp and thus to adapt the general shape of the kinematics of the mobile, to the specifications of the DSA and to the conditions of operational use. The requirements and criteria can be the same as those above for pyrotechnic flaps driven by an electric motor, moving by borrowing gas or any other device 3 S The advantages of the helical ramp are preserved The pitch of the ramp is then adapted according to the specifications of the DSA and the level of the phenomenon

  physical allowing the alignment of the pyrotechnic chain.

  FIG. 4 shows an example of means for driving the shaft 3 which consists of a rack integral with said shaft and a pinion 21. The shaft is held in a safety position by the locking device 24 (shear pin for example) This pinion is rotated by the gear motor 22 via the axis 23 Of course, this motor is controlled conventionally during the flight sequence. Not powered, the gear motor is free The DSA is in the safety position by the action of a reminder device

(spring for example).

  The power supply of the reducing motor, generated by the munition according to a determined sequence, conditions

  the pyrotechnic alignment, the locking device being broken.

  The return device is then compressed by the pyrotechnic flap. In a degraded situation, a power failure or end of autonomy of the energy source (the motor being then free) causes the transition from the "armed" position to the position

  "unarmed" shutter by action of the reminder device.

  FIG. 5 shows another example of drive means operating by the action of the hydrostatic pressure. For this, the shaft 3 is provided at one end with a piston 25 provided with a seal 26 and sliding in a 2 S room 27 It communicates with the outside through the holes 28

  practiced in the lid 29 secured to the body of the ammunition.

  At impact on the water, the shaft (or the pyrotechnic flap) remains in its "safety" position thanks to a return device not shown (spring for example) Hydrostatic pressure; increasing, exerted on the piston 25 of the shutter, conditions

  the alignment of the pyrotechnic flap.

  The reminder device makes it possible to control the moment

  alignment of the shaft according to the desired depth.

  For this device, a safety pin, housed in 3 S the hole 30 provided with a flame, can be placed on the shutter for configurations storage, transport, implementation, until

drop of the ammunition.

  FIG. 6 shows an example of drive means for shaft 3 applicable to aerial and possibly underwater ammunition. One end of shaft 3 is provided with a piston 31 equipped with a seal 32 sliding in a chamber 33 The chamber is closed by a cover 34 which leaves the piston facing a sampling circuit

combustion gas.

  In the safety position, the pyrotechnic flap is held in the "unarmed" position by the locking device 36, not shown. The pressure of the gases taken from the thruster or any other subassemblies of the munition, for example a gas generator or a pressure vessel, is brought via the pipe 35 into the chamber 33, the gas flow being effected following a

sequential determined.

  The gas pressure exerted on the piston 31 of the pyrotechnic flap allows the alignment of the pyrotechnic chain, the blocking device 36 of the flap then being lifted, erased or

  sheared according to the blocking principle used.

  The return device allows a return of the flap in the safety position in case of degraded situations in flight. The concept developed following a groove (ramp) form

  helical (combined and progressive movement of translation -

  rotation) is particularly suitable for this type of ammunition and only allows to reduce or even eliminate the harmful effects of these constraints. This concept is applicable to versions

  of the DSA, the electrical circuit not being modified.

Claims (1)

1 ammunition security and arming device, able to ensure the alignment of the pyrotechnic chain and can occupy two different positions, a first in which the firing of the ammunition is prohibited and a second in which the setting fire is transmitted, characterized in that it consists of a chain interruption means (3) comprising a passage (2 a) made in a diameter perpendicular to the directions of the stresses sustained by the munition during the operational phases, integrating or not a relay composition (2), ute operated along a helical path of angle a to bring the passage (2 a) of the first so-called security position in which it is located in a plane substantially orthogonal to the axis of alignment (6) of the pyrotechnic chain, in the second so-called arming position where it is aligned with the axis of the chain (6). 2 Device according to claim 1, characterized in that the helical movement is the combination of a translational movement and a rotational movement α of about 90 '. 3 Device according to claim 2, characterized in that wi the helical movement of the means is carried out in three successive phases, a first phase A during which it ensures above all a translational movement and a low rotation between about 0 and 15 % of the angle a, then in a phase B of significant rotation between about 15 and 85% of 2 v the angle a, and finally in a phase C especially a translational movement and a small rotation to the position army. 4 Device according to claim 3, characterized in that the means is constituted by a shaft (3) placed perpendicularly to the axis (6) of the pyrotechnic chain, the Muj helical movement being obtained using a pawn assembly guide / helical groove (8,9). Device according to claim 4, characterized in that the helical groove (9) is formed on the shaft (3) according to the profile shown in Figure 3. ç, ^ W 6 Device according to any one of claims 1 to 5 , characterized in that the interruption means is provided with means for displaying the two safety and arming positions. 7 Device according to any one of claims 1 to 6, characterized in that the helical movement is controlled by a rack-and-pinion type motor system (21,20) actuating the interruption means (3). 8 Device according to any one of claims 1 to 6, characterized in that the helical movement is controlled by hydrostatic pressure acting on the interruption means (3). 9 Device according to any one of the claims   1 to 6, characterized in that the helical movement is controlled ij by borrowing gas taken from the propellant of the ammunition   acting on the interruption means (3). -J i O