US2547437A - Explosive rivet firing device - Google Patents

Description

April 3, 1951 v. M. BUNTS EI'AL 2,547,437

EXPLOSIVE RIVET FIRING DEVICE Filed Aug. 22, 1947 l6 l0 2 14 1a III/Z i V.".."........"Jl I4- ]NVEN T DRE l I l -M VERNON M. BuNTs HENRY BHULBERT BY WW ATTURNEY Patented Apr. 3, 1951 EXPLOSIV E RIVET FIRING DEVICE Vernon M. Bunts, East Syracuse, and Henry C. Holbert, Syracuse,. N. Y., assignors to Easy "Washing Machine Corporation, Syracuse; N.$Y.,

a corporation of Delaware Application August 22, 1947, Serial'No. 770,062

'1 This invention relates .to heating. irons for the .settingand exploding of explosive rivets.

In the art of setting explosive rivets, it is neces- 'sary to convey heat to the rivet head by contact therewith of a heated bar which, in order to conduct heat satisfactorily, is usuallymade of .a good heat conductivematerial such as relatively pure copper. Such material is relatively soft. and ductile, andis constantly subjected to. the elevated temperature required for quickly exploding the rivet through .contact with the head thereof. Wh'enIthe rivetis set .in sheet metal members having. some resiliency or yield, the reactive shockfrom the rivethead against the detonating iron, isincreased, all resulting in the upsetting. of the copper tip. .In the. course of heating a number. of rivets at a relatively fast rate, which requires relatively high ironheat, the tip of the iron mushrooms, and in ashort space of time, becomes impractical of further use.

The present invention relates to a riveting iron construction which is so adapted as to prevent the mushrooming action of the iron tip, while at the same time being capable of delivering heat to the rivet head with the same dispatch as heretofore accomplished withplain, pure copper tips. The invention more particularly involves the use of a copper tip'h'aving the .end portion thereof positioned Within a steel or other hardmetal sleeve or jacket capable of constraining while hot the copper tip from expanding or upsetting radially as a result of the axial shock received from the rivet upon detonation. The arrangement of such a sleeve, while reducing somewhat the diameter of the copper heat conductor, by its nature acts as a slight heat insulator and permits the tip to operate at the same or a slightly higher temperature so that no loss in efficiency or time taken in exploding rivets is occasioned by the construction.

The above and other novel features of the invention will appear more fully hereinafter from the following detailed description when taken in conjunction with the accompanying drawing. It is expressly understood, however, that the drawing is employed for purposes of illustration only and is not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawing, wherein similar reference characters refer to similar parts throughout the several views:

Figure 1 is a perspective view of an electric iron having a tip constructed in accordance with the invention;

3. Claims. (Cl. 218-'19) Figure 2 isalongitudinal section of the tip construction;

Figure 3 is an. enlarged showing of a-tip in engagement with the head of an explosiverivet; and

Figure 4 .isan exploded view in perspective showing the parts of which the tip is composed.

Referring .to Figures land 2, there is shown a typical hand electric iron or heating unit such as is ordinarily employed for soldering purposes, the tip of which is constructed in accordance with the invention to adapt it-fordetonating explosive rivets. Theriron is provided with a central hollow core member In around which is located a heating coil [2, an insulating layer l4 and an outer protecting shell 16. The core is providedwith anintegral collar l8, the hollow bore- 20 being adapted to receive the shank end of a'tip assembly. The collar is also; provided with a set screw"22"for affixing the shank of such tip assembly within the core.

In order to provide a' tip adapted to' contact the heads of 'rivets of the'explosive type which will withstand the repeated shock or detonation of the rivet contacted and the heat of the tip, the contactingend of the-tip is protected'with a sleeve ofrelativelyhard material such" as stee or the like.

In the form shown, the shank portion 24* of the tip assembly "isprovided'with' an end bore' 26 intowhich a reduced diameter round copper con tacting member-28 in the form of a rod is in serted with a relatively snugfit. The shoulder 30 thus formed-by the end of the shank portion 24 and the contacting member 28" is adapted'to receive and position a steel sleeve 32 having a beveled end portion-34 suitably shaped to abut smoothly against the-shoulder 30. The shank portion may be preferably tin or nickel plated to prevent oxidation and thereby assure good heat conductive contact with the heater sleeve 10.

In practice, the contacting end 36 of the contacting member 28 is protected against mushrooming by the sleeve 32, as is shown in Figure 3, the projecting end of the contacting member and sleeve being of substantially the same length. As shown in Figure 3, the contacting end has become from slight use somewhat concave, to afford a contacting area with the head 38 of an explosive rivet 40. The steel sleeve 32 terminates at or just short of the surface of the head 38 and thereby confines the contacting tip from flowing or mushrooming as a result of the shock of detonation and the soft nature of the copper readily accomplished by removing the sleeve 32 which may not necessarily make a very tight contact with the contacting bar and thereafter removal of the contacting bar from the shank to make room for the insertion of a new contacting bar. It will be readily appreciated by those skilled in the art, that'the construction is such as to afford a tight connection between the contacting bar and the shank portion for'the transfer of heat therebetween. The steelsleeve being of relatively low conducting material acts to some extent as a heat insulator, causing the contacting bar to conduct heat more readily to the tip without substantial heat loss. The slight air gap between the sleeve and the contacting bar adds to the insulating value of the sleeve.

While it is preferable to form the shank and contacting member of relatively pure copper because ofv the superior heat conducting characteristics of such material, other materials having similar properties may be used if desired. The retaining shank may be made of drill steel or other material as maybe found suitable. The tip end of the contacting member may be flat to contact flat head rivets, or may assume the concave shape shown for round head rivets.

, ,Though a single practical embodiment of the invention has been illustrated and described, it is understood that the invention is not limited to the particular iron shown or the particular shape of the parts illustrated. As various changes in construction and arrangement of the parts may be made without departing from the spirit of the invention, as will be apparent to those skilled in the art,-reference will be had to theappendedclaimsfora-definition of the limitsof the invention.

.- -We.claim:--

. V 1. An explosive riv t=firing device comprising ashank portion adapted for exposure to a source of heat, a heating means sunrrounding said shank, a heat conducting rod extending axially from said shank and terminating in an end face having a plane contacting surface, said rod being of a material of high heat conductivity and relatively low resistance to mushrooming from rivet explosion recoil in the region adjacent said end 4 face, said rod at its rear end being received in an axially directed socket in said shank and abutting the bottom of said socket, and a sleeve snugly surrounding said rod, and terminating substantially flush with said end face, said sleeve being of a relatively hard material of relatively low heat conductivity and capable of confining said rod against radial expansion and preventing mushrooming under the recoil effect of an exploding rivet in contact with the end face, the rear end of said sleeve abutting the front end of said shank for securing said sleeve against axial movement along said rod in a direction away from said end face.

2. A device according to claim 1, in which the rod is of copper, and the sleeve of steel.

3. An explosive rivet firing unit for insertion in arivet exploding tool having means for transmitting heat to said firing unit comprising a heat conducting rod terminatingin a single transverse continuous smooth end contacting surface, said rod being of a material of high heat conductivity and relatively low resistance to mushrooming in the region adjacent the end surface from rivet explosion recoil acting substantially normal to said end surface, and a sleeve snugly surrounding said rod and terminating substantially flush with the marginal edge of said single end surface at all points thereof to confine the rod, said sleeve being of a relatively high strength hard material of relatively low heat conductivity and capable of confining said rod against radial expansion and preventing mushrooming under the recoil effect of an exploding rivet head in contact with said end surface, and rigid abutment means coacting with said rod and said sleeve for prevent-1 ing rearward, axial movement of said rod and sleeve and maintaining the sleeve end substantially fiush with the forward end surface of said rod.

VERNQN M. BUNTS. HENRY C. HOLBERT.

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

UNITED STATES PATENTS 2,411,859 Harwood Dec. 3, 1946

Images