IL98219A - Delay fuse for sequentially detonating shaped charges - Google Patents

Description

PA 98219 A DELAY FUSE FOR SEQUENTIALLY DETONATING SHAPED CHARGES A DELAY FUSE FOR SEQUENTIALLY DETONATING SHAPED CHARGES The present Invention relates to a delay fuse for placing between two shaped charges mounted in tandem in a French patent FR 2 559 896 a delay fuse making use of an protective On detonation of the front charge in the the protective screen moves rearwards and causes an electrical circuit to be Such a configuration makes it possible to obtain considerable delays milliseconds to 3 while avoiding the need to use a conventional solution with coils of great lengths of fuse when using this even the slightest in the required time delay means that action must be taken either on the total mass of the or else on the the screen is to Such geometrical modifications are particularly difficult to perform since they give rise to changes in the dimensions of the warhead and also in the distribution of its total long delays require long distances to be and this degrades the compactness of the An object of the present invention is to provide a delay fuse between two shaped charges mounted in tandem that enables to the value of the time delay to be changed without disturbing the geometrical and ballistic characteristics of the Another object of the present invention is to make it possible to reduce the distance between shaped charges that are to be detonated in sequence without thereby reducing the firing delay between these The invention thus provides a delay fuse for a warhead including at least two charges for detonating in sequence and disposed inside a the delay fuse comprising a screen suitable for moving in axial translation inside the casing and under the effect of the first charge detonating from a starting position to a destination position in which it acts on control for firing a second which fuse is characterized in that it includes a component of compressible material disposed inside the casing between the screen and the control The screen may be fixed to the casing by shearable fixing means and the crushing strength of the compressible material is such that its volume reduces by less than when it is subjected to a pressure equal on warhead launch to the quotient of the inertia of the assembly constituted by the first charge and the screen divided by the area of the first The crushing strength of the compressible material is preferably such that its volume reduces by less than under a pressure of and that it reduces by at least under a pressure of the compressible material is an organic foam having a density of not more than 250 a polyethylene foam or a polyurethane The screen may be constituted by a safety and arming device for the first and the screen may be separated from the first charge by a The block is partly made of a sintered metal material of density lying in the range 1500 to 3000 The means for controlling firing of the second charge may include a piezoelectric Other advantages of the invention appear from reading the following description of a particular which description is made with reference to the accompanying drawing which is a diagram of a delay fuse in accordance with the With reference to the accompanying a fragment of a 1 is shown It includes two shaped charges mounted in tandem inside a casing and intended to be fired in The front charge 3 is fired first in convention manner and comprises a covering 4 and an explosive filler A detection system fires it by means of a safety and arming device 3 A block 7 is disposed between the filler 5 the safety and arming device It is designed to protect said device from the effect of the front charge 3 It is preferably made of a sintered metal material of density lying in the range to sintered The rear charge 8 is shown in this case as being of larger calibre than the front charge and it comprises a covering 9 and an explosive filler A second safety and arming device 11 serves to fire the and it is connected by conductors to firing control means in this by a electric generator The first safety and arming device 6 acts as a protective for the rear charge and it is kept separate from the piezoelectric generator 12 by a component 13 made of compressible In a manner analogous to that described in French patent 2 559 the screen is towards the rear of the warhead by the front charge The function of the screen is to act on the control means so as to cause the rear charge to be fired after a certain time interval The function of the compressible component is to absorb a of the kinetic energy of the screen by This makes it possible rstly to damp the effects on the rear charge due to the front charge and secondly to increase the time taken by the screen to act on the control for given screen mass and compared with a delay configuration in which no compressible component is is thus possible to obtain longer delays with a shorter for for a 200 ms the invention makes it possible to obtain a saving of of in the distance on the hardness of the Depending on the mechanical and geometrical characteristics of the component made of compressible the screen may act directly on the control means after said compressible element has been completely or partially or else it may act on the control means indirectly via a certain residual thickness of the compressible For it is possible to provide a screen that carries a projecting portion 14 which is received in an axial cylindrical bore 15 of the compressible This projecting portion acts on control means of the type disclosed in patent FR 2 a piezoelectric or by closing an electrical A retaining washer 16 may be disposed between the compressible element and the control means in order to isolate the control means from the forces generated by the compressible while the screen is which makes it possible to avoid premature firing of the rear charge when using a piezoelectric The compressible element is preferably selected so as to have crushing strength such that its volume reduces by less when it is on warhead to a pressure equal to the quotient of the inertia of the assembly comprising the first charge and the screen divided by the area of the first The compressible component can then be used as a retaining cornponent capable of withstanding the inertia of the assembly constituted by the front charge and its safety and arming device when the warhead is launched an acceleration of less than 1000 In most it suffices to select a material whose volume reduces by less than under a pressure of pascals and whose volume reduces by at least under a prcissure of Full satisfaction can be obtained with organic foams of density no greater than 250 such as polyethylene foams or polyurethane Under severe acceleration than 1000 it is possible to provide means for fixing the screen to the casing an adhesive or else pins that shear when the front charge insufficientOCRQuality

Claims (9)

98219/2 C L A I M S

1. A warhead delay fuse device including a casing and at least a first charge and a second charge longitudinally axially disposed apart from each other inside said casing, comprising: control means disposed within said casing for firing said second charge; a movable screen disposed in said casing axially movable from a starting position to a detonating position to prompt said control means in initiate firing of said second charge, and compressible material disposed within said casing between said movable screen at said starting position and said control means.

2. The device of claim 1, further comprising shearable fixing means to fix said screen of said casing.

3. The device of claim 1, wherein said compressible material has a crushing strength such that volume of said compressible material is reduced by not more than 5% under a pressure of 6 8 10 Pa, and is reduced by at least 90% under a pressure of 10 Pa.

4. The device of claim 1, wherein said screen is defined by a safety and arming device.

5. The device of claim 1, wherein said control means is defined by a piezoelectric generator.

6. The device of claim 1, wherein said compressible material is an organic foam having a density of not greater than 250 3 kg/m . 98219/2

7. The device of claim 6, wherein said organic foam comprises at least one material selected from the group consisting of polyethylene foam and polyurethane foam.

8. The device of claim 1, further comprising a shock-absorbing block disposed between said screen and said first charge .

9. The device of claim 8, wherein said shock-absorbing block is made of sintered metal having a density between 1500 3 3 kg/m and 3000 kg/m . For the Applicant, Sanibrd T. Colb & Co. C: 017 1-1273