US2441939A - Fuse - Google Patents

Description

y 1943- H. J. NIICHOLS 93 FUSE Filed Nov. 14, 1959 Im mn Patented May 18 1948 UNITED STATES ATENT FEECE 9 Claims.

This invention relates to base detonating fuses,

especially adapted for use with anti-tank projectiles and other small caliber high-explosive projectiles intended for use against armored or protected targets.

The invention will accordingly be hereinafter described with relation to such application but it is to be understood that without material modification many features are equally applicable to larger caliber projectile fuses.

Detonating fuses for small high explosive projectiles present particular difiiculties because of their small size, the great accelerating and rotary forces to which the parts are subjected in firing and in flight, and the heavy forces encountered at impact. Because of the desire to obtain maximum penetration of armor, a nose fuse, which would necessitate weakening the front end of the projectile is generally considered undesirable and a base fuse is preferred. Because of the extreme force of set-back, on firing some projectiles the detonator may be fired by concussion. Also the detonator may be subject to accidental explosion by fire while the fuse is in storage, transport, or service. These hazards make it highly. desirable that the fuse be detonator-safe, by which term is meant that the detonator be held in safe position in the fuse until the projectile has cleared the muzzle. A further desirable feature is that the fuse be not completely armed until the projectile has travelled some distance beyond the muzzle of the gun. This is termed a "muzzlesafe feature. In order to insure certain arming and sensitivity, it is highly desirable that the percussion device be virtually dynamically balanced with respect to the axis of rotation of the projectile in flight, which is also the axis of the fuse.

Finally, from the practical standpoint, fuses of this class should 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 the general and special requirements above stated.

Another object is to provide simple and rugged arming means which utilize forces generated .by the firing process, but- Which are not affected adversely thereby, nor by the forces and shocks incident to handling. 7

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

- hazards.

2 Another object is to provide means for delaying the arming of the detonator until after the projectile is in flight, or muzzle-safe" feature.

Another object is to provide a novel and effective bore-safe and detonator-safe construction as a precaution against concussion or fire Another object is to provide simple and practical means for cushioning the shock on the detonator on firing.

Another object is to provide simple arming means for the detonator which after rotating the detonator is inherently incapable of being thrown from armed position by forces produced by impact with the target.

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 thefeatures of construction, combination of parts, and in the unique relation and coordination 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 drawings like characters of reference denote corresponding parts throughout the several views, in which- Fig. 1 shows greatly enlarged, in longitudinal section a base percussion detonating fuse of small size according to the invention, the mechanism ,being shown in unarmed or safe condition.

.cross section in armed position.

Fig. 3 is a top or inner end view of the fuse.

Fig. 4 is a bottom or base view of the fuse.

Referring now to these drawings and especially to Fig. 1, the mainmember of the fuse is the body I!) of rugged proportions with flange H and external screw threads l2 near the base end l3 for assembly to the projectile (not shown). The body Ill is bored out from the point end i l to provide an internal bore I5 in which the mecha- ,nism is assembled. Starting at the base l3, a

small axial core or cavity i8 is threadedto receive the lower portion of an anti-creep spring ll. A middle bore or cavity 58 is adapted to house a percussion plunger 28, to be described in detail later. The nose cavity 2i is adapted to receive a rotor sleeve 22, mounting a rotary detonator holder or centrifugal rotor 23, and also a booster cup 24, containing a booster charge of compressed -.tetr y1 or the like. The point end is. of the fuseiis closed by a sealing'di'sc 25, over which a lip 27 of the fuse body is spun, or otherwise closed or constructed to form a tight seal. The parts 22 and 2 may be die-cast integrally, if desired.

The percussion plunger 28 comprises asupport or pedestal 23 having an internally threaded cavity 29 adapted to receive the upper :portion of anti-creep spring ll, the threads being .bored out for a short distance at the mouth of cavity '29 to enable the middle coils of spring ll to stretch without interference "with the screw threads. 'The purpose of this spring ll is to prevent the percussion :plunger 29 from being thrown forward after firing when the projectile strikes the atmosphere, and during flight.

The percussion plunger includes element 30 of hollow cylindrical form, which is substantially closedat the top 3 I, and hasan internal-cavity 32 fitting easily over the pedestal '28. 'Mou nted'in the axis of the element 30 is a firing pi-n33 comprising a firing point 3' 2, a collar -35 and a=s lightly tapered punch'36 at the opposite end. Collar 35 is securely "set in a recess 16: in the element '30 by riveting the edge of the recess 'over the collar. Punch 36 rests on top of pedesta-1'2 3, which latter is of such thicknes that when the fuse is fired, the set-bac'k force on element "3 9 and firing pin 33 w illcause the punch 3-6 to pierce the top o'f the pedestal 28 and to remain securely wedged therein due to the taper on the punch see Fig. 2).

The 'rotor sleeve 22 is of hollow cylindrical form with a rectangular -hole adapted to receive the rotor 23, the latter being of short cylindrical form and lying edgewise in rotor sleeve '22. The

rotor has a diametrical round hole adapted to L receive a cylindrical detonator :capsule :40. The detonator capsule is preferably a thin drawn copper shell, in which a highly compressed detonating'c'h-arge "is loaded. The assembly of the detonator isnompleted by covering the detonati-ng charge, loaded not quite to the top, :b-y a thindisc 4 cemented in place by a water iprodf -icement. When the detonator capsule are :is loaded "into the rotor, it is coated with a strong adherent cement to hold the capsule securely in place in the rotor .23. The rotor :is :providedwith rarsmall tapered hole 38 (Fig. 2') located at an angle 'cof approx mately :to the axis :of the detormtor Ml, this .h'olezb'eing adapted tozreceive the point $4 of the illing pit-1 33 when the rotor is :in safe position asshown in Fig. 1.

The rotor '23 is :of centric-symmetric form, being of the type filSClDSBd in my application Serial No. 1303294, filed November "7, .1939, so that while is virtually statically ibalan'cedasiit liesfin bhe it is strongly dynamically unbalanced with :respectto rotationabout the axis of the fuse, which is likewise substantially-the axis of rotation of the projectilewh-ile in flight. V

lRreferring td-Fig. 2d, on, each-end of the rotor 23a central. channel '43 may be cut at slight inclination'to the axis of the detonator Ml. This leaves two symmetrical lands M on each end of the rotor, oisegmental shape, which lands produce the dynamic unbalance. The dynamically unbalanced areas are indicated by the portions between the dotted lines and periphery of the holder as shown in Fig. 2. There is also some minor unbalance due to the detonator capsule and the firing pin hole 38, but the rotative effect produced thereby is generally too small to be material, and for purposes of understanding the principle of the rotor, the lands 44 may be considered to produce the-main and effective rotative effect. The-slight iinc'lination of these lands to the axis of the detonator hole, previously men- .tioned suflices to compensate for minor unbal- 'ance and friction, so that after firing the axis of the detonator is aligned substantially with the axis .of the fuse. It has been found that the channel separating the lands can be parallel to *theraxisiof :the detonator in most cases.

Referring again to Fig. 1, between a shoulder 2! in the 'bore l5 of the fuse body H3 and the rotor sleeve 22 is assembleda disc 45, termed the support discgofthin elastic:metal arranged to cushion the shock on the detonator M! on firing, thereby minimizing the possibility of premature detonation due to concussion. The disc 55 is provided with a small axial hole 36 .thru which "the point- 34 of :firin'g .pin 33 normally extends to engage thehole iw 'an-d restrain the rotor in .safe position.

The booster oup 24 is mounted between the rotor block 22 and-sealingdiscflfi. It is provided :a small :diameter -axial hole "M, counter bored :at ithe upper end to receive a small metal cup 48, halld'the icord "protector icu'p. The interior of the cup.;is 'ffillefl with tightly compressed cord :or 'tetryl :or the like for transmitting the detonation from the detonator .to the "booster chargeflfi. purpose of the cup "48 is to protect'rthe' :cm'dfrom moisture, and :also ".fIOIll hot .gasestlikely'ltobe pruduced'in :event of premature explosion lot "the detonator 455.

The :fuse :is assembled into the projectile by .spanners rengagmgvrecesses 549 :as shown in Figs. -1 ands. the ioperationiis as follows: On all ,parts tend :to :move towards the base 1 3 'dlreitwset-fba'ck? The element ii] carrying firing pin 3311s "afiected :by :this force, :and :moving backdr ives :therprmchifi t'hruthe :top of pedestal 2B and causes thersameito-wedgetherein, securely attaching these :parts as showniin "Fig. 2. The .fir-

3.4 fisthereby drawn :from the hole 38 in :the outer :23 and the rotor would be free to arm then except'fthatithe set-back" :force presses the rotor :tightlyagainst disc 45. The 'rotative force :due todytramiceunbaflance being minor compared to the "set-back fierce, the rotor is prevented fromrotating and remains in the position shown Fig. :1 as done 'zas-the projectile is in the bore of the gun.

it should be :noted here :that not only is 'the motor .Zinnddetonator 40 cushioned against the shock :dfwfiring :by .disc -45, but in the event the detonator is exploded despite this cushioning or by fire, it-he 811 1301; of \the detonator explosion will .be-itoexpandwthe rotor and to wedge a plug of .metalgfllqmithe rotor intothe hole :occupiedbythe protector cup 48 :secunely sealing :same against the entIy of lmt'zgases. The protector :cup'A-B will shield the FtetryI :cord from 'mechanical shock to a -degree sulfi'c'ient 1:0 prevent dellagration. The i gases from 'the detonator will expand into voids in the fuse, including "the space over the plunger }3B,;and'wi;llbe cooled and rendered harmless 'by such expansion.

The possibility of the acceleration of theprojectile being reversed in the bore of the gun due to coppering or other obstruction also requires consideration. In such event, the elasticity of the disc 45 will cause the rotor 23 to rebound therefrom and strike the booster cup before it can respond to rotative forces, and if the percussion plunger 28 is propelled forward, the firin pin 34 will strike the rotor 23 and retain the detonator in safe position. Hence it is evident that the invention provides adequate safeguards against premature explosion of the detonator before firing and while the projectile is in the bore of the gun, and the fuse can be properly termed bore-safe.

Referring to Fig. 2 as to position of the percussion plunger 20, and to Fig. 1 as to position of the rotor 23, as the projectile leaves the muzzle of the gun, and the force of the propellant becomes spent, the acceleration of the projectile ceases, and deceleration due to air resistance occurs. At this instant, disc 45 will throw the rotor forward, but after rebound, the rotor is free to arm, and at the same time the rotation of the projectile due to firing is a maximum, hence the unbalanced forces cause the rotor to turn into the position shown in Fig. 2. The fuse is now completely armed and at some safe distance beyond the muzzle of the gun. The tendency of the percussion plunger 20 to pitch forward due to airresistance, termed creep," is countered by the anti-creep spring II.

On striking a target, the projectile will encounter substantial resistance, and will be checked in flight. This brings into play strong decelerating forces, and the percussion plunger 20 will be propelled forward, overcoming the anticreep spring I! and stabbing the firing pin into the detonator, exploding same. The wave of detonation therefrom will travel through the tetryl cord 48 and booster charge 25 to the projectile burster charge, not shown but assumed to be of high explosive, whereby the projectile is fragmented.

It is to be noted that When the rotor 23 is in armed position shown in Fig. 2, the dynamic unbalance no longer exists, but there remains a torque couple holding the rotor in armed position and there is no tendency towards, nor possibility of, the rotor being thrown out of armed position while the projectile is in flight. Furthermore, on impact with an obstruction, due to the cylindrical shape of the rotor, inertia forces cause the rotor to wedge tightly in its mounting structure, and it cannot be thrown out of armed position by any combination of impact forces. This is of importance in connection with oblique impact, particularly against armor plate, under which circumstances strong random forces are applied to the fuse, and if the rotor can be thrown out of position, incomplete detonation or a dud may result. The rotor of the invention is therefore self-locking in the armed position.

While no particular provision is made to obtain delay in bursting after impact, it is known that by incorporating in the detonator capsule special retarding compositions, a short delay burst can be obtained without material modification of the fuse.

It will be evident to those skilled in the art that the embodiment of the invention, shown and de scribed as a detonating fuse, can be readily converted into an ignition fuse by simple modifications, such as substituting a cap or primer for the detonator, a port or powder pellet for the tetryl cord, and a charge .of powder for the tetryl booster. Such modifications properly come, and

6 are so intended, within the scope of the invention as claimed.

Without further analysis the foregoing will sofully 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 follow ing claims.

I claim:

1. In a base detonating percussion fuse, in combination, a fuse body having an axial bore,'and detonating means assembled therein including a booster holder with a booster charge sealed therein, a stationary element having a. cavity with a centrifugally rotatable detonator holder mounted rotatably therein, a detonator mounted in said holder in safe position, a percussion element for exploding said detonator including a firing pin positioned rearwardly of and in restraining engagernent with said holder, means for enabling said firing pin to move rearwardly to armed position when said fuse is fired in a gun, and means for restraining forward movement of said percussion element in flight.

2. In a base detonating percussion fuse, in combination, a fuse body having an axial bore, and detonating mechanism assembled therein including a booster holder containing a booster charge, astationary member with a cavity having a centrifugally rotatable cylindrical detonator rotor mounted rotatably therein with its axis at right angles to the axis of the fuse, a cylindrical detonator mounted diametrically in said rotor in safe position, a percussion element mounting a firing pin for exploding said detonator slidably mounted in said bore rearwardly of said rotor, means including said firing pin for maintaining said rotor in safe position until said fuse is fired in a gun, and means for sealng said mechanism in said body.

3. In a projectile fuse of base detonating percussion type, in combination, a fuse body having an axial bore, sealing means therefor, and an assembly of mechanism sealed therein including symmetrical rotor means carrying a detonator assembled in safe position, rotor means selfrotatable responsively to centrifugal force for turning said rotor means and detonator from safe to armed position when the projectile is in flight, and setback armed percussion means including a firing pin positioned rearwardly of and in restraining engagement with said rotor means for exploding said detonator on impact of the projectile with the target.

4. In the combination set forth in claim 3, said percussion means including a pair of elements normally maintaining said firing pin in restraining engagement with said rotor means, said elements telescoping when the fuse is fired in'a gun to remove the restraint of said firing pin on said rotor means.

5. In detonating mechanisms for base detonating percussion fuses, in combination, a fuse body having an axial bore, and detonating means assembled therein including a centrifugally rotatable detonator carrier mounting a detonator and located with its center of gravity substantially on the axis of said bore, a percussion element positioned rearwardly of said carrier including a firing pin for holding said carrier in inoperative position until said fuse is fired in a gun and thereafter for exploding said detonator on imdetonating mechanism assembled therein including a stationary member with an axial cavity having a centrifugally rotatable cylindrical detonaitor rotor rotatably and concentrically mounted therein, a detonator mounted diametrally in said rotor at the center of gravity thereof, a percussion element positioned rearwardly of said rotor including a firing pin for exploding said detonator, set-back actuated safety means forming part of said percussion element for normally holding said firing pin in restraining engagement with said rotor, and anti-creep means for restraining said percussion element from forward movement when alrmed.

"7. A detonati-ng percussion fuse for a rotative projectile having, in combination, a fuse body adapted for assembly into such a projectile hav- :ing an axial bore and closing means therefor, and an assembly of exploding mechanism enclosed therein comprising, a centrifugal detonator rotor carrying a cylindrical detonator mounted therein transversely to the axis of said bore, a percussion device including a movable firing pin positioned 230 axially and in rotation preventing engagement with said rotor, and means for releasing said rotor for centrifugal rotation when the projectilebarrying said fuse is discharged from a gun.

8. Abase detonating percussion fuse for a rota- :t-i-ve projectile having, in combination a fuse body adapted for assembly into such a projectile having an axial bore and closing means therefor, and an assembly of detonating mechanism enclosed therein comprising, a centrifugal'detonator rotor of circular main section with a detonator mounted .in a diametricail bore therein and transversely to the axis of said body, stationary means for rotatably mounting said rotor, an inertia percussion plunger including a firing pin for exploding said 4:5

detonator positioned axially in rotation preventing engagement with said rotor, and an anticreep device arranged to restrain movement 'of said plunger towards said rotor during flight of said projectile.

9. A base detonating percussion fuse for a rotative projectile having, in combination, a fuse body adapted for assembly into the base of a projectile and having an axial bore with closing means therefor, and exploding mechanism assembled therein comprising, a holder containing an explosive booster charge, a detonator for initiating the explosion of said charge normally safely positioned in a rotor, a centrifugally operated detonator rotor for turning said detonator from safe to armed position responsively to the spin of said projectile, an inertia percussion plunger including an axially movable firing pin normally positioned to prevent rotation of said rotor to armed position, and anti-creep means for restraining said plunger from movement towards said rotor during flight of the projectile.

HARRY J. NICHOLS.

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

UNITED STATES PATENTS Number Name Date 431,273 Martin July 1, 1890 654,108 Ashton July 17, 1900 766,022 Dawson et el .July26, 1904 1,311,1ce Watson Ju'ly.2'2, 1919 1,311,673 Baldwin July 29, 1919 1,534,611 Watson Apr. 14, 1925 1,550,977 Lukens Aug. 25, 1925 1,550,978 Lukens Aug. 25, 1925 1,865,802 Towner July 5, 1932 1,774,943 Summerbell Aug.26, 1930 2,014,393 Mathsen Sept. 1'7, 1935 2,155,100 Scelzo Apr. 18, 1939 FQREIGN PATENTS Number Country Date 257,333 Great Britain Aug. 2'7, 1926

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