Delayed arming fuze for a spinning projectile

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.

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.

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' is integral with the upper rotor 
carrier 150'. 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' which overlies the inner turns of the 
coil of the unwinding ribbon 146', an inner annular rim 202' which 
overlies the annulus 126' on the firing pin 124', and a ramp camming 
surface 204' which permits the annulus 126' 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' 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' of the firing pin. If 
desired, the annular rim 200' can be increased in diameter to fully 
overlie the coil of the unwinding ribbon 146'.