US2446019A - Detonating or impact fuse - Google Patents

Description

July 27, 1948. H. J. NICHOLS DETONATING OR IMPACT FUSE Filed Nov. 7, 1939 iigji 7 0 j l hl Ir, E

Patented July 27, W48

UNITED STATES PATENT OFFICE 7 Claims.

This invention relates to detonating or impact fuses especially for anti-aircraft or anti-tank projectiles and the like.

Detonating fuses for small anti-aircraft projectiles, for example, offer numerous difficulties because of their small size and the great accelerating and rotary forces to which the parts are subjected in firing and in flight. Yet it is necessary that fuses for this purpose be extremely sensitive on impact, and at the same time be entirely safe in storage, handling, and firing. Because of the force of set-back on firin some projectiles, the detonator may be fired by concussion on firing. This makes a bore-safe feature highly desirable. A fuse to be boresafe must have adequate provisions against arming in the bore of the gun, and in the event the detonator is exploded by concussion, provision must be made against the burster charge of the projectile being exploded and the present invention accomplishes this. A further desirable feature is that the fuse be not armed until the projectile has travelled some distance beyond the muzzle of the gun, since a strong retarding force occurs when the projectile strikes the air on emerging from the gun, and if the sensitive firing elements can co-act, premature firing may result. To insure sufiicient sensitivity on impact with light targets, such as the wings of aircraft, the firing element must be of light weight. To obtain both super-sensitive and super-quick action, special provision should be made that the firing pin first strike the target, and as this element is thereby retarded, the projectile collides with the firing pin, producing detonation before the projectile has been sensibly retarded. In

order to insure certain arming action and sensitivity, it is highly desirable that the arming and firing elements be virtually dynamically balanced with respect to the axis of rotation of the projectile, since otherwise the high rate of rotation of the projectile in flight will produce undesirable unbalanced forces tending to interfere with the intended action and sensitivity.

Finally, from the practical standpoint, fuses of this class should have few parts, be simple in construction, easily loaded and assembled, and adapted to low cost manufacture in large quantity.

It is therefore one of the principal objects of this invention to meet in a highly eficient, reliable, and practical manner thegeneral. and special requirements above stated.

Another object is to provide simple and rugged arming means which utilize forces genings erated by the firing process to effect arming in part, complete arming being dependent upon the action of supplementary kinetic means.

Another object is to provide means for extending the impact firing element after the projectile is in flight.

Another object is to provide a high degreev of safety against premature explosion in handling the fuse, or on firing the loaded and fused projectile.

Another object is to provide a novel tive bore-safe feature.

Other objects will in part be obvious from the annexed drawings and in part hereinafter indicated in connection therewith by the following analysis of the invention.

This invention accordingly consists in the features of construction, combination of parts, and in the unique relation of the members and in the relative proportioning and disposition thereof, all as more completely outlined herein.

To enable others skilled in the art fully to comprehend the underlying features of this invention, that they may embody the same by the numerous modifications in structure and relation contemplated by the invention, drawings depicting a preferred embodiment of the invention form a part of this disclosure, and in such drawlike characters of reference denote corresponding parts throughout the several views, in which- Fig. 1 shows in longitudinal section a pointimpact, detonating fuse according to the invention, the mechanism being shown in unarmed or safe condition. l

Fig. 2 is a similar section, showing the mechanism in armed condition or its condition immediately after being fired.

Fig. 3 show a bottom View of the fuse.

Fig. 4 shows in section details of the rotor or detonator holder taken on 4-4 of Fig. 2.

Fig. 5 is a perspective detail of the spring support.

Referring to these drawings, and especially Fig. 1, the fuse casing includes a body ll! of rugged proportions with external screw threads II at the base end l2 for assembly to the projectile not shown. At the bottom is an internally threaded cavity I3 in which a loaded booster cup l4, containing pressed tetryl or the like, is secured by means of a threaded ferrule IS. The tetryl is covered by a paper disc l6 for protective purposes. The point end I! of the fuse body I0 is provided with an internally threaded cavity 18 adapted to receive the nose piece 20 which forms and effecpart of the fuse casing. Rearwardly of the threaded cavity I8 is a cavity 2| specially shaped to receive the rotor 22 or detonator holder to be described and to cause said rotor at all times to rotate with the projectile when the latter is fired. Because of its shape, this cavity is preferably formed by forging or casting. Extending from the rotor cavity 2|, to the booster cavity is a small diameter axial hole 24, counter bored at the upper end to receive a small metal cup 25, called the cord protector cup. The interior of the cup and the axial hole are filled with tightly compressed tetryl or the like, this part of the' detonating train being termedithedetonating cord. The purpose of the protector cup 25 is to protect the end of the cord frommoisture, and also from hot gases likelyitolbe. generated in event of premature explosion of the detonator 26, carried by the rotor 22.

The rotor 22 is centro-symmetric, that is, it is symmetric twith respectto..its. center of mass. Consequentlygit is staticallybalanced with respect to any axis passing through'its center. Il- -lustratively, such a rotor, may take the form of a right-circular cylindrical memberdisposed edgewise in the rotor cavity 2|, with itsaxis transwerse to the axisof the. fuse body. By .virtue of iitsl special shaping-aforesaid, the rotor cavity, -for the right circular cylindrical rotorillustrated, is provided with a cylindrically curvedbottom --portion and with planeend walls against. which the end faces of the rotor seat. Accordingly, the rotor m'ay turnrelatively to the fuse body on its own axis, but is constrained by engagement of its end-iaces 1With thwend walls of. the .cavity to at all times rotate Withthe-fuse and projectile --when the latter is fired.

Midway of its ends. the v'rotorl has adiamfetral roundhole adapted to receive the cywlin'drical detonator capsule..26. The. detonator capsule preferably is a .thin drawn copper shell, in which the highlycompressed fulminate= deto- "nating charge is loaded. Therassemblyof .the detonator is completed by covering the fulminate -charge, loadednot quite to the top, by athin disc 27 acemented in placeby a water-proof cement. Whenthe -detonatorcapsule' 26 is loaded into the rotors it is coated wthaistrong adherent cement "to hold the capsule-securely:in place in.the rotor 22. Therotonis provided with a small :tapered hole 28 (Fig. 2) located at an angle 45-ormore -td-the axis of thei detonator i26,.this hole being adapted to receivethe: point 30 ofithe firing pin 6 |-When the rotor isin the safeiposition as shown in Fig. 1.

In addition to the rotor .22 being formed so that it is virtua-lly statically-balanced with respect to its axis, it is also so constructed that in its assembled-position and priorto arming,'it is *dynamically-unbalanced with respect-to the axis of the fuse, which' islikewise substantially the alaxis ofrotation of the projectile accordingly, and referring to Fig. 4, on each end of the rotor 222- a- 'central channel 32 is cut at an inclination mfsay *to the axis of the-detonator 26. This leaves two lands 33 on each end of the rotorin "the 'form of segments contained within the cir- -cular-section of the rotor, each-subtending an larc ofapproximately-120; which segments pro- "duce the dynamic unbalance. FThe unbalanced areas are indicated by the portionsbetween the dotted'lines and:peripheryin Fig. 2. There is also 'some -minor unbalance due to the detonator hole andits contentsg but because of the rela- 11 tively -small r diameter" of 'this hole and the po- "The firing pin, having a sharp pointed inner end .:3|I.and a rounded head 3'! extending outside the nose piece 20, is larger in diameter at the head -of-its shank,-which shank is circled by a groove ..38 (Fig. 2). .Thenose piece 20 and spring support 34 maintain the firing pin 3| in position in the-axis of the fuse. The nose piece axial hole is counter-bored from.the inner end to provide a barrel '40 :in whichvworksa small setback ring .4.|,'also the extender springi=36. ,The topwcoil 36c of the extender spring;36-is of smalleridiameter than the other coils, and fits snuglyintojthe gIO0Ve:'38 in the firing pin shank 3|.'

The various .threadedzparts of the fuse;arelassembled by spanners engaging recesses :39 was shown in .Fig. 1. ';.Then-..the. operation is as follows: On firing,.-. all partstend to move away .from the. point 31 by reason of. the acceleration of firing; termed :fset-back. The'set-back. ring 4|: and extender-spring 3B; .are..aife'cted by-:;this force, and thetop coil 360 of the spring .is forced out of the groo.ve.:3|l in .the'firing.pinsshankaiil, due to the.=inertia of the ring and of the spring itself; and moves rearwardly ;until .the collfl36c rests below. the taperedlshoulderi 42; ofthe-firing pin. The. .firing, pin 30, supported. by-aitshead 31, remainsin the hole in the rotor=22, preventing the. rotor: from rotating, although the set-back force onthe rotortisnormallyiadequate to prevent'rotation of the rotor while the projectile is in the bore. of the. gun.

.It .should" be noted. here that; int event ;the detonator 261's exploded by theconcussion of .fir-

.ing, the rotor. 22 :is being pressed against .the bottom of the rotor cavity 2l-with great pressure, and the effect of .the:detonator explosionwill be to wedge a plug of metal from the rotor into, the top: ofithe. axial cord' hole1124, securely sealing ..same.against'.the'entry ofhot gases. ;The. cord protector cup 25 will shieldthe tetryl cordfrom mechanical shockwto adegree sufiicientto,- preventzshockdetonation. The gases from the-adetonatorwill :expandintothe voidsiin thefuse, the set .back force sufiicingyto. preyentrexpulsmn of the firing pin.

Referring nowsto 2, as the :projectlle leaves the-muzzle .of the gun and the forcegof the. propellant becomes. spent, the acceleration -of.the projectile :ceases, and: deceleration: .due .to

the air resistance occurs. 3 At this instantwthe extender spring? 36. advancesthefiring. .pin 30 to extended position as shown in Fig. 2. The rotor iS'l'lOW freed;.of the restraint of the firing pin r 30 and the set-back force; and at the same time the rotation. of .:the projectile'due to. firingds a maximum. Thus ithe=.,dynamic unbalance of the rotor 22 takes effect and causes the rotor to rotate.the':detonator:.26.into axial; position as shown. "The fuse is now completelyarmed (at somedistancebeyondthe muzzlecf the guntand on striking the .target,-, even though thee-target abe. a flimsy one,=-suchas the. wing fabricbf an airplane;v thethead' {31 of the. firing -pin will -en-.

counter substantial resistance and will be checked in flight. The projectile will then relatively drive the detonator 26 into the firing pin 30, instantly detonating the former. The wave of detonation will travel through the tetryl cord 24 and booster charge [4 to the projectile burster or high explosive charge (not shown) but of standard construction. The detonation wave travels so rapidly that the projectile will burst within a few inches of the point of encountering the target. As is well known to those versed in this art, the firing point 30 is made sharp, and the top layer of the detonator charge is of particularly sensitive composition to promote sensitive firing action.

It will be evident that the invention provides novel and advantageous features and adequately meets the general and special requirements forz fuses of this class.

Without further analysis the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various applications without omitting certain features that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of the invention, and therefore such adaptations should and are intended to be comprehended within the; meaning and range of equivalency of the following claims.

I claim:

1. In afuse of the class described, in combination, a fuse casing, a centrifugally actuated rotatable cylindrical detonator holder mounted therein, a detonator mounted diametrally in said holder in safe position, an axial detonator firing pin in restraining engagement with said holder, safety means for maintaining said firing pin in said restrainng engagement, and spring means adapted to act on said firing pin to advance said firing pin from said restraining engagement to armed position after the fuse is fired in a projectile.

2. In a fuse for rotative projectiles, in combination, a fuse body having an axial cavity, a centrifugally rotatable cylindrical detonator holder rotatably mounted in said cavity, a nose piece mounted on said body, a detonator firing pin axially mounted in said nose piece in safe position, a detonator diametrally mounted in said holder and normally maintained in safe position by said firing pin and rotor, and firing pin arming means adapted normally to maintain said firing pin in safe position and on firing of the projectile automatically to release said firing pin and immediately after firing to move it into firing position.

3. In a fuse of the class described, in combination, a head striker detonator firing pin, a centrifugally actuated cylindrical detonator rotor carrying a detonator normally maintained in safe position by said firing pin, and firing pin arming means actuated on firing in a gun to release said firing pin, and after firing to advance said firing pin to armed position, thereby to release said rotor and to permit said detonator rotor to rotate said detonator to armed position.

4. In a fuse for a rotative projectile, a selfaligning and self-locking centrifugally actuated detonator safety rotor comprising a cylinder having a central diametral bore and rotatably mounted with its axis transverse to the axis of the fuse, a cylindrical detonator mounted in said bore with its axis oblique to the axis of rotation of the fuse, and means including a passage in said rotor extending parallelly with respect to the axis of said detonator for generating angularly limited torque responsively to centrifugal force resulting from the spin of the projectile in flight, thereby to rotate said detonator from safe to armed position and to maintain the detonator in armed position.

5. As an article of manufacture, a centrifugally actuated detonator safety rotor having torquecouple masses for use in rotative projectile fuses comprising a cylindrical member with a central diametral cylindrical hole adapted to contain a detonator capsule, and at least one passage in said cylindrical member disposed substantially parallelly to said hole, thereby to produce a torque-couple responsively to centrifugal force acting to rotate said member about its axis.

6. In a detonating fuse for rotative projectiles a centrifugally actuated detonator safety rotor comprising a rotatable member having a central diametral bore adapted to carry a detonator capsule and having integral means for producing torque acting to rotate said member to armed position responsively to centrifugal force, said means comprising symmetrical masses formed by at least one passage extending diametrally across said member in a direction substantially parallel to said diametral bore.

7. In a detonating fuse for rotative projectiles, a centrifugally actuated safety rotor comprising a cylindrical member having a central diametral bore adapted to carry a detonator capsule, and also having integral means for producing a torque-couple responsively to centrifugal force, said torque-couple acting to rotate said member about its axis to armed position, said means comprising lands formed by a groove extending diametrally across the end of said member in a direction substantially parallel to said bore.

HARRY J. NICHOLS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,316,607 Watson Sept. 23, 1919 1,561,687 Brayton Nov. 17, 1925 1,774,043 Summerbell Aug. 26, 1930 2,155,100 Scelzo Apr. 18, 1939 FOREIGN PATENTS Number Country Date 505,055 France Apr. 28, 1920 687,004 France Apr. 22, 1930 809,246 France Dec. 3, 1936 837,467 France Nov. 12, 1938

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