US3353489A

US3353489A - Impact fuze for a spinning projectile

Info

Publication number: US3353489A
Application number: US528706A
Authority: US
Inventors: Berger Fritz
Original assignee: Rheinmetall GmbH
Current assignee: Rheinmetall Industrie AG
Priority date: 1965-02-26
Filing date: 1966-02-21
Publication date: 1967-11-21
Anticipated expiration: 1984-11-21
Also published as: CH432300A; BE676972A; GB1133960A; DE1259740B; NL6602380A

Description

Nov. 21, 1967 F. BERGER IMPACT FUZE FOR A SPINNING PROJECTILE Filed Feb. 21, 1966 Fig.2

2 .6 xx a a 2 b t 4 4 B 9 v Inventor: Fm fZ Berger United States Patent 3 tClaims. Cl. 102-79 ABSTRACT OF THE DESCLOSURE A percussion fuze for spinning projectiles having means operative by centrifugal force to place the fuze in firing position as to the slidable firing pin and having a rotor adapted to be adjusted into an ignition position by the centrifugal force but held in non-ignition position during transport by a second rotor safety device.

The invention relates to an impact fuze for a spin ning projectile, the fuze having a rotor adapted to be righted into an ignition position under the effect of centrifugal force, and having an axially slidable striker pin bearing, in the transport position, against .a supporting surface of the rotor and securing it against movement to an ignition position.

In a known impact fuze for a spinning projectile having a rotor adapted to be righted into an ignition position by centrifugal force, the rotor has a supporting surface disposed transversely of the axis of the fuze and which is arranged as a bearing for movable blocking bodies of a locking device which are adapted to be brought out of contact with the rotor. The locking device is provided, in turn, with movable release members for terminating the locking of the rotor and securing the blocking bodies against displacement when the rotor is in the transport position, the release members and the blocking bodies operating in succession and thereby releasing the rotor for righting or erection, the rotor being merely moved by friction.

A method of that kind for securing the rotor is not satisfactory, however, when greater bore safety is required, bore safety being an indication of the distance the projectile must travel before the fuze is ready for operation. For this reason, this known impact fuze just mentioned has been improved so that the rotor is able to right itself only by means of parts of the locking device. This righting into the ignition position is achieved because the blocking element, which bears on the supporting surface of the rotor in the transport position thereof, is removed in the ignition position of the rotor, and, at the same time, contact between the striker pin of the impact fuze and the rotor is prevented during the righting movement thereof. In other words, a safety or securing element is displaced on firing and a shortening thereof thereby occurs, so that after the acceleration of the projectile is complete the blocking members are lifted away from the supporting surface of the rotor by centrifugal force. The blocking members engage also below a shoulder of the striker pin and lift the latter while the blocking members move beyond the shoulder. As a result, the rotor can now right itself into the ignition position. In this position the bore safety is at an end.

The blocking members may consist of four small blocks provided with conical surfaces or it may be a one-piece slide which is pushed aside by the centrifugal force and releases the striker pin in the process.

In this known impact fuze, the blocking members determine the bore safety, i.e. as the blocking members fiy outwards they not only release the rotor for righting, but at the same time also free the striker pin. Particularly great bore safety cannot be achieved in this way.

In another known impact fuze, the transport position of a centrifugal rotor is ensured by a striker pin which can be displaced on the longitudinal axis of the fuze. This is done by means of a flattened portion of the cylindrical surface of the rotor, against which the striker pin is supported. Between the striker pin, which extends into a recess in the rotor, and the tip of the fuze there are two rotor safety devices, first a fusible pellet mounted in the tip of the fuze and which can be melted by the heat of the ram pressure due to the forward movement of the projectile and by which the striker pin is prevented from moving axially and thereby releasing the rotor, and, second, two arms articulated to the striker pin and having roller-shaped centrifugal bodies, which tend to draw the striker pin forward under centrifugal force and thereby release the rotor. After the projectile has left the barrel of the weapon from which it is fired, the pellet melts owing to the heat of the ram pressure, and the striker pin is drawn forward by the force of the centrifugal bodies and the rotor is able to right itself into the ignition position. The bore safety is thereby at an end.

If it is borne in mind that it must be possible to carry out firing over a temperature range of 30 C. to +30 C., this gradient of 60 C. amounting to about one half of the melting temperature of the pellet, which consists of Woods metal, then it becomes clear how dependent the commencement of the melting of the pellet is on the air temperature. Since, however, the bore safety is at an end with the drawing along of the striker pin which follows immediately thereon, the bore safety will be at an end close in front of the barrel if melting of the pellet begins prematurely.

Finally, there is also known an impact fuze with a rotor safety device in which the locking means holding the rotor in the transport position consists of a split ring which can be expanded radially by centrifugal force and releases the rotor to such an extent that the latter is able to right itself from the transport position into the ignition position.

On release of the rotor, a blocking slide located in front of a flash hole in the fuze is moved aside, so that an ignition path from the rotor to the projectile charge is now exposed.

Owing to the fact that the centrifugal force only has to spread the split ring, the bore safety is very small in this known impact fuze.

The common drawback of all known fuzes is that the construction of the various safety devices can be achieved only with constructional elements which are complicated and costly and/or unsafe in operation.

Therefore, the problem underlying the invention is to produce an impact fuze for a spinning projectile in which a rotor adapted to be righted into the ignition position by centrifugal force is held in the transport position by an axially slidable striker pin which bears against a supporting surface of the rotor, the fuze being distinguished by an improved bore safety which is independent of external influences, in spite of the fact that its internal arrangement consists of only a few robust parts.

According to the invention, there is provided a second rotor safety device which consists of a blocking device Whose effect is terminated a known time after the first safety device has become inoperative.

The blocking device may consist of a coiled band adapted to expand radially and which is pretensioned and embraces the rotor over its full width when the rotor is in the transport position. Instead of the coiled band,

it is also possible to employ other blocking elements which also delay the righting of the rotor.

By way of example an embodiment of the invention will now be described in detail with reference to the drawings, in which:

FIG. 1 shows in longitudinal section an impact fuze with a self-destroying arrangement and a coiled band in the transport position, and

FIG. 2 shows in longitudinal section the impact fuze illustrated in FIG. 1 after the bore safety is at an end.

The impact fuze illustrated consists of two main structural systems, namely a self-destroying system and the bore safety device system.

The self-destroying system is mounted in the front part of a fuze casing 1 and is followed at the rear by the bore safety device system. The self-destroying system, which is known per se, consists of a sleeve 2 with a bearing surface 3, a ball carrier 4 with balls 5, and a spring 6. These parts surround a fuze plunger 7, which has its upper (as seen in FIG. 1) end located behind a diaphragm 8 and extends at its lower end into a central bore in the ball carrier 4. The lower part of the ball carrier 4 is in the form of a striker pin 4a with a projecting striker point 4b.

In the transport position of the fuze which is shown in FIG. 1, the striker point 4b extends into a blind bore 9a in a rotor 9, which is, in turn, mounted in a cavity formed between the sleeve 2 and the fuze body 10. A percussion cap 12 is inserted in a central bore 11 in the rotor 9.

The lower end face of the striker pin 4a bears on a flat portion 13 of the rotor 9, the latter having also another fiat portion 14 extending parallel to the axis of the fuze and the width of which corresponds approximately with the distance between the sleeve 2 and the fuze body 10. This flat portion 14 is surrounded by a coiled spring band 15 which is given a slight initial tension, which enables the band to form a compact spring bundle. The coiled band 15 is housed in a cage 17 arranged at right angles to the axis of the fuze and symmetrically with respect to the axis of the rotor, the external diameter of the cage 17 being such that the internal diameter of the coiled band 15, when it is opened out as it expands outwardly, is larger than the outer diameter of the closed coil. Below the rotor 9 there is a central bore 16 in the fuze body.

The fuze operates in the following manner:

In the transport position shown in FIG. 1, the rotor 9 has its axis symmetry in an inclined position with respect to the axis of the fuze. In this position, it is held both by the percussion pin 4a, which is subject to the effect of the spring 6, and by the coiled band 15, so that the striker point 412 cannot penetrate into the percussion cap 12 in the rotor 9 and nor can transmission of ignition take place, even in the event of the occurrence of premature ignition of the percussion cap 12.

Under the effect of the acceleration of the projectile which occurs on firing, the entire internal arrangement of the fuze remains in the transport position shown in FIG. 1. Towards the end of the acceleration period, i.e. when the projectile has emerged from the mouth of the barrel of the weapon from which it has been fired and the centrifugal force takes full effect owing to the spin of the projectile, the balls 5 are moved outwards along the bearing surface 3 of the sleeve 2, the balls pushing the axially displaceable parts, consisting of the ball carrier 4 and the fuze plunger 7, towards the upper end of the fuze in opposition to the force of the spring 6. In this process, the striker pin 4a is lifted away from the flat surface 13 and the striker point 4b is lifted out of the blind bore 9a, so that the rotor 9 is no longer secured from this side. The righting or erection of the rotor 9, however, is delayed by the coiled band 15, which begins to fly outward as the centrifugal force becomes operative, until the full peripheral surface of the rotor tiU 9 passes through the innermost turn of the outwardflying coiled band 15. The rotor 9, which is likewise subjected to the effect of the centrifugal force, rights itself out of its inclined position until its axis of symmetry coincides with the axis of the fuze.

As shown in FIG. 2, when the second safety device has also become inoperative, the range of flight designated as the bore safety margin has now been completed. If the fuze now strikes the target, the tip of the fuze and the fuze plunger 7 are forced in, and the percussion cap 12, which is now freely accessible in the rotor 9, is pierced by the striker point 4b and the percussion cap in turn causes detonation of the detonator (not shown) and thereby of the bursting charge via bore 16.

It is also possible to employ other safety devices instead of a coiled band 15, as long as they provide the requisite delay in the righting of the rotor.

In the self-destroying system, the ascended balls 5 hold the pretensioned spring 6 over a part of the trajectory under the effect of the centrifugal force. If, however, in the further course of the flight of the projectile, the speed of rotation of the projectile steadily decreases, there comes a moment when the axial component of the centrifugal force becomes smaller than the force of the spring 6, and the latter is able to cause the striker point 4b to move forward against the percussion cap 12 by way of the ball carrier 4, so as to cause in this way the self-destruction of the projectile at a predetermined point along its trajectory.

I claim:

1. A percussion fuze for spinning projectiles comprising a casing having a front part and a rear part, a sleeve secured in the rear part of the casing and having a bearing surface, a ball carrier with balls mounted slidably in the casing and in the sleeve, and having a striker pin secured thereon, a fuze body secured in the rear part of the casing and spaced from the sleeve, a rotor mounted to rotate between the fuze body and the sleeve and having a coiled band around the rotor and having a percussion cap therein; and a fuze plunger slidably mounted in the casing and extending into the sleeve, said rotor being normally held in inoperative position by the coiled band and when the projectile is fired centrifugal spinning force will act on the band to hold the rotor in an unarmed position for a predetermined period of time so that when the balls in the ball carrier force the latter away from the rotor the striker pin will be in a position to plunge into the percussion cap when the projectile strikes a target.

2. A percussion fuze according to claim 1, in which a cage is formed between the sleeve and the fuze body to accommodate the coiled band so that the latter will be arranged symmetrically in relation to a rotor axis.

3. A percussion fuze according to claim 1, in which a cage is formed between the sleeve and the fuze body to accommodate the coiled band so that the latter will be arranged symmetrically in relation to a rotor axis, and in which the outside diameter of the cage is dimensioned so that when the band is open, the inner diameter of the coil is larger than the outside diameter of the closed coil.

References Cited UNITED STATES PATENTS 2,656,793 10/1953 Howell lO2-8O 2,682,835 7/1954 Meister 10279 2,782,717 2/1957 Burri et al. 102-79 X 2,921,527 1/1960 Guerne 102-79 3,033,115 5/1962 Guerne 102-79 X 3,112,704 12/1963 Schaadt 10279 X 3,136,253 6/1964 Kulesza et al. 1OZ79 BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner.

G. H. GLANZMAN, Assistant Examiner

Claims

1. A PERCUSSION FUZE FOR SPINNING PROJECTILES COMPRISING A CASING HAVING A FRONT PART AND A REAR PART, A SLEEVE SECURED IN THE REAR PART OF THE CASING AND HAVING A BEARING SURFACE, A BALL CARRIER WITH BALLS MOUNTED SLIDABLY IN THE CASING AND IN THE SLEEVE, AND HAVING A STRIKER PIN SECURED THEREON, A FUZE BODY SECURED IN THE REAR PART OF THE CASING AND SPACED FROM THE SLEEVE, A ROTOR MOUNTED TO ROTATE BETWEEN THE FUZE BODY AND THE SLEEVE AND HAVING A COILED BAND AROUND THE ROTOR AND HAVING A PERCUSSION CAP THEREIN; AND A FUZE PLUNGER SLIDABLY MOUNTED IN THE CASING AND EXTENDING INTO THE SLEEVE, SAID ROTOR BEING NORMALLY HELD IN INPOPERATIVE POSITION BY THE COILED BAND AND WHEN THE PROJECTILE IS FIRED CENTRIFUGAL SPINNING FORCE WILL ACT ON THE BAND TO HOLD THE ROTOR IN AN UNARMED POSITION FOR A PREDETERMINED PERIOD OF TIME SO THAT WHEN THE BALLS IN THE BALL CARRIER FORCE THE LATTER AWAY FROM THE ROTOR THE STRIKER PIN WILL BE IN A POSITION TO PLUNGE INTO THE PERCUSSION CAP WHEN THE PROJECTILE STRIKES A TARGET.