Abstract:
The provision of a delayed arming fuze utilizing a ball rotor, and a firing pin which is captured to the ball rotor by an unwinding ribbon, and which pin precludes the rotor from swinging into alignment for arming until the ribbon has unwound under the sequential presence of setback and spin forces.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to fuzes for ammunition for normally maintaining the ammunition in a safe configuration and for shifting to an armed configuration upon the concurrence of setback and centrifugal forces. 
     2. Prior Art 
     Fuzes of this general type are well known in the prior art, and are shown, for example, in U.S. Pat. No. 3,397,640, issued to Ziemba et al on Aug. 20, 1968; U.S. Pat. No. 3,595,169, issued to Ziemba on July 27, 1971; U.S. Pat. No. 3,608,494, issued to Ziemba on Sept. 28, 1971; U.S. Pat. No. 3,489,089, issued to Kaiser et al on Jan. 13, 1970; U.S. Pat. No. 3,302,572, issued to Lindberg et al on Feb. 7, 1967; U.S. Pat No. 3,479,955, issued to Birkigt on Nov. 25, 1969; U.S. Pat. No. 3,516,359, issued to Weber et al on June 23, 1970; U.S. Pat. No. 3,616,757, issued to Berger on Nov. 2, 1971; U.S. Pat. No. 3,585,935, issued to Birkigt on June 22, 1971; U.S. Pat. No. 3,994,230, issued to Kahn on Nov. 30, 1976; U.S. Pat. No. 3,995,557, issued to Engel et al on Dec. 7, 1976; the USAR A-20, A- 23 and A-25 projectile fuzes, and the US XM722 and XM714 projectile fuzes. These fuzes employ various combinations of ball rotors, unwinding ribbons and/or dash pots. However, none provides a system which permits the rotor to arm a consistent and predetermined interval of time after both spin and setback forces are present simultaneously. The dash-pot design of the XM714 and XM722 particularly has problems with (1) aging seals, (2) air leaks, (3) piston surge, (4) ambient temperature and pressure sensitivity, (5) spin rate sensitivity and (6) parts lubricity. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide a delayed arming fuze for a spinning projectile which provides arming after a consistent and predetermined interval of time after both spin and setback forces are present simultaneously. 
     Another object is to provide such a fuze which includes a point detonation function, a grazing function and a self-destruction function. 
     Still another object is to provide such a fuze which is insensitive to the effects of temperature, pressure and aging. 
     A feature of this invention is the provision of a delayed arming fuze utilizing a ball rotor, and a firing pin which is captured to the ball rotor by an unwinding ribbon, and which pin precludes the rotor from swinging into alignment for arming until the ribbon has unwound under the sequential presence of setback and spin forces. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     These and other objects, advantages and features of the invention will be apparent from the following specification thereof taken in conjunction with the accompanying drawing in which: 
     FIG. 1 is a view in longitudinal cross-section of an embodiment of this invention showing the components of the fuze in their safe configuration; 
     FIG. 2 is a view similar to FIG. 1, showing the components in their configuration upon undergoing setback; 
     FIG. 3 is a view similar to FIG. 2, showing the components in their configuration upon undergoing spin; 
     FIG. 4 is a view similar to FIG. 3, showing the components in their armed configuration; 
     FIG. 5 is a view similar to FIG. 4, showing the components upon point detonation; 
     FIG. 6 is a view similar to FIG. 4, showing the components upon self-destruct detonation; 
     FIG. 7 is a view similar to FIG. 4, showing the components upon graze detonation; and 
     FIG. 8 is a view in longitudinal cross-section of another embodiment of this invention showing the components of the fuze in their safe configuration. 
    
    
     DESCRIPTION OF THE INVENTION 
     The fuze includes a lower fuze body 10 having an upper interior cylindrical longitudinal bore portion 12, a lower cylindrical longitudinal bore portion 14, an interior annular base portion 16, an exterior annular flange portion 18 and an exterior threaded portion 20 for securing the fuze to the main charge. An upper fuze body 22 is secured to the lower body by means of an annular groove 24 which receives the flange 18, and has a first cyclindrical longitudinal bore portion 26, a second cylindrical longitudinal bore portion 28, a third cylindrical longitudinal bore portion 30, a fourth longitudinal, conical, bore portion 32, and an annular groove 34. 
     A nose cap 36 is secured to the upper body 22 by means of an annular flange 38 which is received by the groove 34 and has a blind longitudinal bore 40. 
     A cylindrical upper rotor carrier 50 is disposed in the bores 30 and 12 and includes a lower blind cylindrical longitudinal bore portion 52 opening into a semi-circular recess having a transverse axis 53 and two spaced apart longitudinally extending flat side walls bounding the cylindrical wall 54. The wall 54, at each end thereof, extends into a flat ramp portion 56. The carrier 50 also has two transversely extending blind cylindrical bores 58, each receiving a respective ball 60. The carrier has a boss 62 with an annular recess 64. 
     A cylindrical lower rotor carrier 70 is disposed within the bore 52 and has a longitudinal bore 72 opening into a semi-circular recess having a transverse axis 53 and two spaced apart longitudinally extending flat side walls bounding the cylindrical wall 74. The wall 74, at each end thereof, extends into a flat ramp portion 76. The cylindrical walls 54 and 74 define a cylindrical opening about the transverse axis 53. The ramp surfaces 56 and 76 define two recesses 80 and 82 opening onto this cylindrical opening. An exterior annular shoulder 84 is formed on the carrier. 
     A cup 90 is also disposed within the bore 12 and has an exterior annular flange 92 resting on the base portion 16. A helical compression spring 94 is disposed between the flange 92 and the shoulder 84 and biases the lower carrier 70 against the upper carrier 50. The cup has a longitudinal bore 96 thereon which opens into the well 98 of the cup in which a booster charge 100 is disposed. 
     A cylindrical rotor 102, having an axis of rotation which is perpendicular to the longitudinal axis of the fuze, and coincident with the transverse axis 53, is disposed in the cylindrical opening 54/74. The rotor has a transverse, diametrical bore 104 in which is disposed a detonator 106, a radial blind bore 108 in which is disposed a ball 110, a pair of transverse blind bores (not shown), each adapted to receive the tip of a respective spring retained locking in 116, 118, and a radial blind bore 120 adapted to receive the stab end 122 of a firing pin 124. Each locking pin 116, 118 is disposed in a cup 119a which is captured in slots in the upper and lower rotor carriers, and has a leaf spring 119b fixed to the outer end of such pin. On assembly, the pins are disposed in their radially inwardmost positions and are held there by the friction of the ends of the leaf springs within the respective cup. 
     The firing pin 124 further has an annular shoulder 126, a neck portion 128, a body protion 130 and a bearing portion 132. The bearing 132 slides in the bore 26 of the upper fuze body 22. 
     A two piece hollow split collar 140, 142 has a lower flange disposed in the annular recess 64 of the upper carrier, and an upper flange disposed in the recess of the neck portion 128 of the firing pin. A helical compression spring 144 is disposed on the firing pin and is adapted to bias the pin away from the rotor. The split collar is held together by a metal ribbon 146 wound about the collar as a spool. If desired, a cover 148 may be disposed about the ribbon and fixed to the upper carrier. The split collar captures the firing pin to the upper rotor carrier. 
     In the safe configuration, as shown in FIG. 1, the firing pin 124 is captured by the split collar and its aft end projects into the bore 120 of the rotor while its forward end abuts the end wall of the blind bore 40 in the cap. The wound up ribbon 146 precludes the opening of the split collar. The captured firing pin precludes rotation of the rotor. The spring inwardly biased pins 116 and 118 also preclude rotation of the rotor. 
     Upon setback, as shown in FIG. 2, the whole assemblage of upper rotor carrier 50, lower rotor carrier 70, rotor 102, firing pin 124, ribbon 146 and split collar 140 moves aft against the bias of the spring 94. The forward end of the firing pin is spaced from the end wall of the blind bore 40. 
     Upon spin, as shown in FIG. 3, the balls 60 move outwardly and engage the ramp surface 56 of the upper fuze body, wedging, or frictionally holding, the upper carrier aft with respect to the fuze body. The pins 116 and 118 move outwardly against the friction of their springs, disengaging from the rotor. The ribbon 146 commences to unwind from the split collar. After a period of time, the ribbon is unwound from the collar and the two parts of the collar 140 and 142 move outwardly, disengaging from the firing pin, and the spring 144 then biases the firing pin forwardly, removing the aft end from the bore 120 of the rotor and abuting the forward end against the end wall of the blind bore 40. The rotor is then free to rotate, and precesses to align the detonator 106 with the longitudinal axis of the fuze, to the armed configuration, as shown in FIG. 4. The ball 110 moves outwardly in its bore 108 and engages the ramp surface 56, wedging, or frictionally holding, the rotor in its aligned position with respect to the rotor carrier. 
     Upon point detonation, as shown in FIG. 5, the nose 36 is crushed, moving the firing pin aft, against the bias of the spring 144, to percuss the detonator. The detonator, in turn, ignites the booster 100. 
     Upon the spin decreasing sufficiently to no longer hold the balls 60 out against the ramp surface 56 to wedge the rotor carrier aft, the spring 94 biases the assemblage forwardly to percuss the detonator against the stationary firing pin, as shown in the self destruct configuration of FIG. 6. 
     Upon a grazing impact, the spin is also decreased to no longer hold the balls 60 out against the ramp surface 56 to wedge the rotor aft. The spring 94 biases the assemblage forwardly to percuss the detonator against the stationary firing pin, as shown in the graze configuration of FIG. 7. 
     The embodiment shown in FIG. 8 differs, inter alia, from the embodiment of FIG. 1 in that the split collar 140&#39; is integral with the upper rotor carrier 150&#39;. The collar is here shown to be divided along longitudinal planes into eight parts, each part being a cantilevered beam with its proximal end integral with the carrier. The distal parts of the collar provide an outer annular rim 200&#39; which overlies the inner turns of the coil of the unwinding ribbon 146&#39;, an inner annular rim 202&#39; which overlies the annulus 126&#39; on the firing pin 124&#39;, and a ramp camming surface 204&#39; which permits the annulus 126&#39; to deflect the parts outwardly when the firing pin is pushed in during assembly. The carrier is made of a relatively resilient material, such as glass fiber reinforced nylon 6/10. A creep spring 144&#39; is also provided. Under the application of centrifugal force, the ribbon unwinds away from the collar and the distal ends of the collar deflect outwardly to release the annulus 126&#39; of the firing pin. If desired, the annular rim 200&#39; can be increased in diameter to fully overlie the coil of the unwinding ribbon 146&#39;.