US3830159A - Mechanism - Google Patents

Abstract

A returnable setback safety mechanism for fuzes of spin stabilized artillery in which the safety pin is depressed upon setback or rearward force exerted upon the mechanism. The safety pin will return to its original safety position after setback unless the mechanism is then subjected to projectile spin forces as a result of the projectile being launched.

Description

[ Aug. 20, 1974 Emma iates Patent 1 Ranalli et al.

2,897,760 8/1959 Mott-Smith....................... l02/80 X 3,450,049 6/1969 MECHANRSM [75] inventors: Nicholas J. Ranalli; James C.

both of Cornwells Heights,

Mount,

Primary ExaminerSamuel W. Engle Attorney, Agent, or Firm-Edward J. Kelly; Herbert Berl; William Sommer Army, Washington, DC.

Nov. 6, 1972 ABSTRACT [22] Filed:

[21] Appl' 303898 A returnable setback safety mechanism for fuzes of spin stabilized artillery in which the safety pin is de- [52] U.S. pre ed upon setback or rearward force exerted upon the mechanism. The safety pin will return to its origi- [51] Int. Cl. F42c 15/20 102/78, 79, 80, 7O

nal safety position after setback unless the mechanism is then subjected to projectile spin forces as a result of the projectile being launched.

[58] Field of Search References Cited UNITED STATES PATENTS 2 Claims, 2 Drawing Figures 2,448,228 8/1948 McCaslin et 102/80 X MECHANISM The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to mechanisms, and more particularly to a safety mechanism for artillery fuzes.

A non-returnable setback safety mechanism may become locked in an armed condition if dropped from above a predetermined height whereby the mechanism will have its effectiveness limited because it will arm and lose its safety function at relatively low setback G values. 7 It is an object of the invention to provide a setback safety mechanism in which the safety pin is positively returned to a safe unarming position unless the setback force is immediately followed by a predetermined amount of sustained artillery spin.

Another object of the invention is to provide such a mechanism in which safety and reliability are enhanced.

These and other objects, features and advantages will become more apparent from the following description and accompanying drawings in which:

FIG. 1 is longitudinal sectional view of a spin stabilized artillery fuze safety mechanism embodying the principles of the invention.

FIG. 2 is a view similar to FIG. 1 wherein the mechanism has been subjected to sequential setback and sustained artillery spin forces as in the launching of a projectile.

The safety pin 11 of the returnable setback safety mechanism shown generally at (FIG. 1), normally extends in the path of an unarmed rotor body 12 of a spin stabilized artillery fuze mechanism to prevent the rotor body 12 carrying detonator 13 from rotating about its own journal means (not shown) to move the detonator to an armed position where it will be exposed to an appropriate ignition means or firing pin arrangement. The rotor body journal axis is parallel to the longitudinal spin axis 14 of the fuze mechanism so that the rotor body 12 can rotate in a plane normal to spin axis 14 for movement to its armed position when safety pin 11 is held in a depressed condition (FIG. 2) as will be hereinafter described. The pin 11 normally extends along the centerline 15 of the safety mechanism which is parallel to and axially offset from the spin axis 14.

The safety mechanism has a screw body 16 provided with external threads 17 by which it is suitably secured within the fuze mechanism, a forwardly opening cylindrical recess 18 in which is seated compression spring 19 that normally biases forwardly the head 20 on the rearmost end of pin 11, and an enlarged forwardmost recess 21 by which the cover member 22 can be secured, as by staking, to the forward end of the screw body. The cover 22 is centrally apertured to normally receive the shaft of pin 11 and has a conical ramp surface 23 on its rearward internal portion to facilitate return of safety pin 11 to its normal safe position should the safety mechanism be subjected to a setback force without any accompanying spin forces. To this end the forward portion of safety pin 11 is provided with a hemispherical tip 24 which is directed or cammed by the ramp surface 23 through the central aperture of the cover 22 when the spring is extended after being compressed. The screw body recess 18 is defined by a cylindrical wall having a diameter less than the periphery of the cover 22 and preferably slightly greater than the periphery of the conical ramp surface 23. The safety pin 11 of the setback safety mechanism is positively returned to the FIG. 1 safe unarming position unless the setback force is immediately followed by a predetermined amount of sustained artillery spin.

Upon firing of the artillery projectile, the safety pin 11 first experiences setback and compresses the spring 19 to solid height. Before setback ceases, projectile spin forces the pin 11 against the screw body recess wall 18 (FIG. 2). When setback ceases after launch, projectile deceleration and spring bias act on the pin 11 to tend to urge it toward its safe unarming position. However, the projectile is still spinning and the normal force between the pin and the screw body recess wall generates sufficient friction to prevent the pin 11 to return through the cover aperture, thus enabling rotation of rotor body to an arming position as controlled by a fuze timing mechanism (not shown).

Various modifications, changes or alterations may be resorted to without departing from the scope of the invention as defined in the appended claims.

We claim:

1. In a spin stabilized artillery device having a rotor body adapted to move in a predetermined plane substantially perpendicular to the artillery longitudinal spin axis,

a returnable safety mechanism having a pin member normally extending parallel to and axially offset from said spin axis and in the path of said body to prevent movement thereof, said safety mechanism including a screw body having a forwardly opening recess, said pin member having a longitudinal body portion and a head portion at its rearmost end, said body portion being of a diameter smaller than said head portion and both said body and head portions having a diameter smaller than said recess to enable pivoting of said pin member in said recess, a compression spring seated in said recess and engaging said pin head to normally bias said pin forwardly into said path, and a cover member secured to a forward portion of said screw body, said cover member having a forward surface with a central aperture for normally receiving said pin member and a rearward internal surface portion forming a conical ramp over a substantial portion thereof for assuringly directing and returning a forward portion of said pin member through said aperture when said compression spring is extended after being compressed to the extent that said pin member has been withdrawn from said cover aperture as a result of a set back force received by said pin member unaccompanied by any sustained centrifugal force thereto, said pin member having a substantially hemispherical forwardmost tip.

2. The structure according to claim 1 wherein said screw body recess is defined by a substantially cylindrical wall within said screw body, said cylindrical wall having a diameter less than said the periphery of said cover and slightly greater than the periphery of said conical surface.

Claims (2)

1. In a spin stabilized artillery device having a rotor body adapted to move in a predetermined plane substantially perpendicular to the artillery longitudinal spin axis, a returnable safety mechanism having a pin member normally extending parallel to and axially offset from said spin axis and in the path of said body to prevent movement thereof, said safety mechanism including a screw body having a forwardly opening recess, said pin member having a longitudinal body portion and a head portion at its rearmost end, said body portion being of a diameter smaller than said head portion and both said body and head portions having a diameter smaller than said recess to enable pivoting of said pin member in said recess, a compression spring seated in said recess and engaging said pin head to normally bias said pin forwardly into said path, and a cover member secured to a forward portion of said screw body, said cover member having a forward surface with a central aperture for normally receiving said pin member and a rearward internal surface portion forming a conical ramp over a substantial portion thereof for assuringly directing and returning a forward portion of said pin member through said aperture when said compression spring is extended after being compressed to the extent that said pin member has been withdrawn from said cover aperture as a result of a set back force received by said pin member unaccompanied by any sustained centrifugal force thereto, said pin member having a substantially hemispherical forwardmost tip.

2. The structure according to claim 1 wherein said screw body recess is defined by a substantially cylindrical wall within said screw body, said cylindrical wall having a diameter less than said the periphery of said cover and slightly greater than the periphery of said conical surface.

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