US1380738A - Thumb-tack and method of producing the same - Google Patents

Description

w. RAEBURN. I THUMB TACK AND METHOD OF P RODUCING THE SAME.

APPLICATION FILED 1AN.12| I920.

Patented June 7, 1921.

entree WILLIAM nanennn, or wnrnnsnar, CONNEGTZECUT, nssiewon, To

TEANUFACTURING COMPANY, OF NEW YORK, N. L, CORPORATION OF NEW YORK.

THUMB-TACK MID METHQD OF RODUCING TI-IE SAME.

Specification of Letters Patent. Pgatgnigrgd ift ng Y, 13 21.,

Application filed January 12, 1920. serial N0.351,031.

tain new and useful Improvement in Thumb-Tacks and Methods of Producing the Same, of which the following is a full, clear, and exact description.

lily invention relates to improvements in thumb tacks and has for its object to provide a new and improved thumb tack formed from a single piece of sheet metal. Heret cfore thumb tacks have been formed from a single piece of sheet metal by having a shank cut out from the metal so as to form a pin or point integral therewith, leaving an opening from which the shank was out out of dimensions corresponding to said shank. The presence of this opening in the thumb tack is very objectionable, since the thumb tacks when once out out are finished in a rolling barrel and when so treated very often stick together, a prong or shank of one tack entering the opening in another so that not only do the tracks fail to be properly finished but they very often stick together so that it is a very expensive matter to pick them apart and in some cases they will get wedged together so tightly that they have to be scrapped. The object of my invention is to produce a single piece thumb tack in which these difficulties will be avoided, and consists in reducing the opening above referred to so that the difiicultics above mentioned are no longer present. My invention therefore consists in a new and improved thumb tack and method of pro ducing the same.

The following is -a description of my invention, reference being had to the accompanying drawings, in which Figure 1 shows in perspective a thumb tack embodying my invention in thumb tacks, looking at it from the under side;

Fig. 2 shows a top plan view of the same;

Fig. 3 shows in perspective a sheet of metal partially formed into thumb tacks embodying invention and illustrating the method of production;

Figs. 4 and i show the forming dies and punches, and

Figs. 5 and 5 the punches and dies 00- acting therewith.

Figs. 6, 6 and 6 show in detail the swagingpunch.

Referring more particularly to the drawing, Fig. 1 shows my onepiece thumb tack, the same consisting of a head 1, having projccting from. it and integral therewith a point 2, the same constituting ashank which is cut from the body of the metal at all points except adjacent to its base so that its base is integral therewith and bent down to form the prong. After the point is thus formed the metal. on each side of the opening from which the point is cut is swaged, as shown at 3, so that that opening is substantially closed. The swaging thins the metal adjacent to the sides of the opening without affecting the thickness of the larger portionof the head or sheet from which it is formed. The thumb tack, therefore, consists of a head having a centrally located point projecting therefrom and integral therewith, the outer metallic surface of the head being substantially continuous, the opening therein being substantially closed by swaging.

These thumb tacksare made upon a single acting pillar press and in making them 1 preferably use a point-forming punch, a swaging punch, a lettering die, a point straightening die and a blanking die, arranged in the order named. I feed through the press a strip of sheet metal which is first acted upon by the point-forming die 5* at position a, cutting and forming the point shown at 2 in Fig. 3 and leaving an opening 4. The strip is then moved forward to position 7), with the result that the swaging die 5 hits the metal upon each side of the opening 4, forcing it inward so as to sub stantially close the opening, as shown at 3. This swaging punch has an opening 5 to re ceive the point of the partially formed tack and has two slightly raised ridges 5 connected by a slightly curved sunken face 5 for directing the inward flow of the metal. The succeeding punches also have openings 5" 5 5 for the point, the onening 5 in the punch at position (Z being adapted to straighten the point. The strip is then fed forward again to position 0, whereupon the portion originally treated is subjected to embossing dies 6 for impressing upon the ietal destined to constitute the head of the tack any desired lettering or ornamentation. The strip is then fed forward to po sition d so that the point first formed is subjected to straightening dies and is then fed forward to a blanking die and punch 7 at position 0, which cuts out the head and bends it into a slightly concave-convex form, after which the thumb tack is subjected to any desired finishing operation, the first step of which is ordinarily the subjecting of it to the polishing action of a rolling barrel.

Each action of the pillar press produces one tack ready to be polished, preliminary steps on other tacks being performed simultaneously with the final blanking step.

As will be evident to those skilled in the art, my invention permits of various modifications Without departing from the spirit thereof or the scope of the appended claims.

What I claim is:

1. In a sheet metal tack, the combination of a head, a centrally located prong integral therewith and projecting therefrom said head having a radial division extending to the base of said prong and of lesser width than the width of said rong, the portions of said head adjacent to said division being thinner than the larger portion of said head.

52-. The improvement in the process of.

making a single-piece thumb tack which consists in cutting from a sheet of metal a shank, having its base integrally connected to the sneet and leaving a corresponding opening in the sheet and then swaging the metal of said sheet locally adjacent to said opening so as to reduce said opening and thin the metal adjacent thereto without af-s fecting the thickness of the larger portion of said sheet.

WILLIAM RAEBURN.

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