US2987000A - Connector for point initiating to base detonating projectile - Google Patents

Description

June 6, 1961 CONNECTOR N. A. voss ET AL 0 2,987,000 FOR POINT INITIATING TO BASE DETONATING PROJECTILE Filed April 15, 1960 INVENTORS NED A. VOSS BY WILLIAM F KAUFMANNJR. X mm JQ Q JW ATTORNEYS:

United States Patent 2,987,000 CONNECTOR FOR POINT INITIATING T BASE DETONATING PROJECTILE Ned A. Voss, York, and William F. Kaufmann, Jr., Philadelphia, Pa., assignors to the United States of America as represented by the Secretary of the Army Filed Apr. 13, 1960, Ser. No. 22,065 3 Claims. (Cl. 102-70) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to an explosive projectile of a point initiating base detonating type having a connector in the nose just behind a piezo electric generator unit and has for an object to provide a projectile of this type better adapted to withstand higher muzzle accelerations without rupture of the electric circuit connections between the nose and base under the higher stresses created during set back.

In projectiles for guns of a size between about 76 to 120 millimeters, efforts have been made to increase their muzzle velocity to as much as about 3750 feet per second. Among the many difficulties experienced were some in the electrical connectors behind the piezoelectric crystal unit used in the point initiating to base detonating type projectiles. When the increased velocity was applied to projectilesstandardized for lower velocities it was found that in one batch slightly over 50% of them had a break occur in the electric circuit leading from the nose initiator to the base fuze. I More specifically investigation shows a break in the conductor that was in the connector immediately behind the piezo electric crystal unit. Another causewasfracture in the insulator body in the same connector although in this latter situation fracture occurred in less than 50% of the previously standard rounds fired under the increased velocity. Here again the solution was not in selecting a stronger and tougher insulating material because other factors than strength afiect its usefulness, It was seen that an ideal solution should retain the old insulating material for its other advantages and retain the same size of conductor, but how to accomplish this result was a problem. Investigation has shown that increasing the conductor strength by making it larger was not the answer because on set back the additional weight of the flexible conductor also increased the tensional stress it had to withstand.

The present invention is one that has been a great improvement by eliminating the causes of fracture discovered by minute study without change in size or material of which either the conductor or insulator had been made in order to harmonize the cures for both weaknesses. In the conductor, elimination of two small radius 90 bends was made possible with satisfactory results. In the insulator it was thought that the stresses were too numerous and complicated. However, under the present invention one larger radius loop in the flexible conductor arranged in a plane generally parallel to the longitudinal axis of the projectile and to the axis of a conductive eyelet appears to have been the answer to both troubles. It has involved a simplification in the nature of the stresses in the insulator body by now having that body chiefly under compression.

Referring to the drawings:

FIG. 1 is a diagrammatic view of the projectile and the ungrounded side of the electric circuit to which this improvement relates,

FIG. 2 is a longitudinal section through the connector on the line 2-2 of FIG. 3 with the flexible conductor in position in the connector,

FIG. 3 is a right end view of the connector of FIG. 2,

re 2,987,000 Patented June 6, 1961 FIG. 4 is a section on the line 4-4 of FIG. 3 but of the block alone,

FIGS. 5 and 6 are views showing a modification made of stamped metal instead of a block.

In FIG. 1 is shown a conventional projectile 10 having in its nose a customary piezo electric generator unit 11 from which a usual projection 12 extends rearwardly into an electric connector unit 13 from which extends a flexible conductor 14 leading to a base detonator fuze 15. The type and arrangement of explosive within this projectile is not shown because no part of this invention and the projectile elements of FIG. 1 are all broadly old. The reason for FIG. 1 being shown is because the present improvement in the connector 13 enables the projectile to possess the new advantage of being able to be given a higher muzzle velocity without breakage in the electric circuit between the unit 11 and the detonator fuze 15. The ordinary projection 12 is split longitudinally tomake it yie'ldable within a metallic non-yieldable eyelet, yet adapted to make a good electrical contact.

Referring to FIG. 2 the connector 13 of this invention comprises a body of plastic insulating material 16 such as nylon with the usual rear cylindrical flange 17 and a recess in its forward face as shown. Within this recess is placed a block 18 of light weight conductive material such as aluminum having therein a hole 19 extending not only through the block 18 but also through the insulator 16 to its rear face. The projection 12 fits within this hole 19 and makes good electrical contact with the metal 18 due to the expansive resiliency of this split projection, the outer edge 20 of this conductive recess or hole 19 is bevelled to better guide the end of projection into said hole as is common practice. A substantially semi-circular groove is provided in block 18 for reception of the looped end 21 of the flexible conductor 14. As shown in FIG. 2

the forward end portion of the looped conductor 14 does not extend forwardly of the front face of the insulator 16. Block 18 is made of a depth longitudinally in FIG. 2 such that the radius of curvature of the loop may be made large because otherwise it is believed the tendency for the conductor to be broken under tension during set back and due principally to the weight of the conductor wire, would be greater.

FIG. 3 shows how the sides of the wire loop may be allowed to project beyond the side faces of block 18 by providing small additional recessed portions of the depth of block 18. Although the laterally protruding portions of the conductor loop in FIG. 3 are only adjacent the rear face of block 18, nevertheless since the sides of loop 21 are passed around block 18 before it is inserted in the insulator body 16, these additional recessed portions need to extend through the full depth of insulator body 16 in order that the block with the conductor in its groove may be inserted into the body 16 of the insulator. After passing around block 18 the sides of the loop connected preferably by some crimped type of connector 22 capable of withstanding tension in the conductor that is to be induced during set back when the muzzle velocity of the projectile has been raised to approximately 3750 feet per second.

In FIG. 4 the depth of the block 18 is shown as being substantially half its width in order that the arc of curvature for the conductor groove 24 in the block be substantially semicircular and thereby eliminating two short radius bends that were thought to have been the major factors contributing to rupture of the conductors that were found to be incapable of withstanding the higher forces on set back incident to the higher muzzle velocity. In that prior construction the main and substantially semicircular conductor loop was of smaller radius, was around the metal eyelet for receiving the projection (12), and was close to and parallel to the front face of the in- 3: sulator. Such a prior construction is believed to have imposed fiexure and other stresses in the eyelet and insul'ator.

FIG. 5 is a top plan view of a modified embodiment of the present invention in which no metal block 18 is used is cut in stamping axially alined with the longitudinal axis of eyelet 25. The outer edge portion of the eyelet recess is bevelled as was the case in FIGS. 2 and 3.

In both embodiments of the conductive element in the connector, one side of the electric circuit from the piezo electric crystal is grounded to the outer body of the projectile while the other is that through projection 12, connector 13, and flexible looped conductor 14 to the base fuze 15. The exact reasons why this connector, its insulating body with its conductive parts are better able to withstand the forces set up during set back are not fully understood perhaps because the stresses in that prior standardized construction were more complex. This improvement has been proven superior to the old without any increase in size or strength of its parts and the inherent weakness as in both the insulator 16 and conductor 14 have at the same time been largely eliminated.

. 4 r through said projection, connector, and conductor, said conductor having a loop formed therein and extending into said connector, a central metal eyelet in said connector recess into which said projection is received, and an insulator in said connector for positioning said eyelet and loop in said projectile, the combination therewith of the improvement enabling said projectile to be subjected to muzzle velocity of about 3750 feet per second and stress in said conductor from set back with reduced danger of rupture of said conductor and insulator, said improvement including said conductor loop being within said insulator in a plane generally parallel to a longitudinal axis of said eyelet and projectile, and a conductive strip between said loop and insulator and also being laterally between said eyelet and loop, whereby said loop may be semicircular within said insulator, given a radius of curvature about equal to the longitudinal depth of said insulator and said conductor be free of any smaller radius bends than that in said loop and whereby said insulator is subjected to compression under said loop.

2. A combination according to claim 1 in which said conductor eyelet and loop support is a block of metal fitting said insulator and having a groove formed therein for positioning said loop.

3. A combination according to claim 1 in which said eyelet and loop support are a unitary structure and formed from sheet metal.

References Cited in the file of this patent UNITED STATES PATENTS 1,511,622 Lucas Oct. 14, 1924 2,633,800 Cagle Apr. 7, 1953 2,754,756 Duesing July 17, 1956 2,764,091 Hudson Sept. 25, 1956 2,827,851 Farrara Mar. 25, 1958 2,834,292 Viasmensky May 13, 1958 2,849,957 Kuller Sept. 2, 1958 2,894,457 Severance July 14, 1959

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