Ammunition and explosives – Igniting devices and systems – Arming devices
Patent
1995-07-10
1997-04-29
Tudor, Harold J.
Ammunition and explosives
Igniting devices and systems
Arming devices
102234, F42C 1523, F42C 1522
Patent
active
056251610
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The field of the present invention is that of safety devices intended for locking a firing pin for a fuse of a spin-stabilised projectile.
Projectiles, notably medium caliber shells, are fitted with safety devices intended to prevent initiation of the pyrotechnic circuit before firing and during the first few tens of meters of their trajectory.
A known safety device includes a lock, for example, a split sleeve, which immobilises the projectile firing pin in translation, and which is surrounded by a spiral spring consisting of an elastic strip wound upon itself.
German Patent DE1197786 describes such a safety device for a medium caliber projectile fuse.
The lock includes a strip folded back upon itself so as to form a sleeve with a hexagonal profile. The sleeve acts as a stop for a shoulder on the firing pin thus preventing the pin from striking a detonator.
Because of its split structure, the lock is able to open under the action of the centrifugal force exerted upon it during firing. The opening of the lock allows the firing pin to move in translation, for example, at impact on a target.
A spiral spring is wound around the lock. The function of the spiral spring is to delay the time at which the lock opens. Since this opening occurs only after a few tens of meters of trajectory, the gun crew is protected.
The centrifugal force which acts on the spring during firing thus causes it progressively to unwind and to wind up against the wall of a cylindrical housing in the fuse. Once thee spring is completely unwound, the lock can then open and release the firing pin.
Such a device has disadvantages. For example misfires have been observed because the spring can form unwanted loops which interfere with the firing pin and prevent it from moving freely.
SUMMARY OF THE INVENTION
The purpose of the invention is to propose a safety device not suffering from such drawbacks.
The safety device according to the invention ensures that, during firing, the spiral spring remains properly wound against its cylindrical casing without forming unwanted loops that prevent the firing pin from striking the detonator.
Thus, the purpose of the invention is a safety device intended to lock a firing pin for a spin-stabilised projectile fuse, the device including a spiral spring consisting of an elastic strip wound upon itself and held by its own elasticity around a locking device which maintains the firing pin in the safety position, the locking device having a flexible strip wound around the firing pin, the material and geometry of which are such that it exerts no elastic return force towards the firing pin, the length of the strip being such that, when it is unwound during firing following the spiral spring and applied against the spiral spring by the action of the centrifugal force, its ends overlap.
According to one embodiment of the invention, the flexible strip includes grooves, which are preferably orientated towards the firing pin.
The firing pin may then be cylindrical or have a polygonal section, preferably hexagonal.
The grooves may have a variable pitch allowing the strip to wind around the firing pin to form a polygonal shape.
If the firing pin has a polygonal section, the grooves of the strip will then be positioned, as it unwinds, at the corners of the polygon.
According to another characteristic of the invention, the strip is such that, once it has unwound following the spiral spring, its ends overlap on an arc of between 60.degree. and 80.degree..
Another purpose of the invention is a process for producing such a device, the process including a step of manufacturing the grooves in the strip by knurling a smooth strip between a knurling wheel and a backing pulley.
Knurling can be done using a variable pitch knurling wheel.
In a variant, the strip may be pulled between the knurling wheel and the backing pulley by the rotation of a polygonal shaft on which the knurled strip winds up, this polygonal shaft being the firing pin.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better
REFERENCES:
patent: 859610 (1907-07-01), Meig's et al.
patent: 3516359 (1970-06-01), Weber et al.
patent: 4938139 (1990-07-01), Brede et al.
patent: 5147974 (1992-09-01), Bai et al.
Nicolas Jacques
Oberle Jean-Paul
Manurhin Defense
Tudor Harold J.
LandOfFree
Safety device for a spin stabilized projectile fuse, process for does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Safety device for a spin stabilized projectile fuse, process for, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Safety device for a spin stabilized projectile fuse, process for will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-707914