US2712768A - Fastener strip and method of making same - Google Patents

Description

July 12, 1955 R WINKLER 2,712,768

FASTENER STRIP AND METHOD OF MAKING SAME Filed July 11, 1950 Zmnentor Ric/lard Winkle)" United States Patent Ofiice 2,732,7ss Patented July 12, 1955 2,712,768 FASTENER STRIP AND METHOD 0F MAKING SAME Richard Winkler, Chicago, Ill., assignor, by mesne assignments, to Bocji Corporation, Pittsburgh, Pa., a corporation of Delaware Application July 11, 1956, Serial No. 173,185 4 Claims. (Cl. 8517) This invention relates to fasteners of a type which are formed from a strip or ribbon of metal, the strip being processed to provide a connected series or strip of individual fastener blanks, and the present invention is for an improved fastener strip and method of making the same.

In the formation of a strip of fastener blanks of the type to which the present invention relates, an ribbon or strip of metal is slit at regular intervals to provide a succession of leg-forming elements, these slits extending diagonally from the edge toward the center of the strip, and the slit then extending longitudinally for a distance sufiicient to form a leg element of the desired length. Such fastener strips are commonly coiled or wound upon reels, which reels are placed in a driving machine designed to. feed the strip to a driver wherein the forming of the blanks is completed and they are progresdriven as individual fasteners.

One specific form of such a strip of fastener blanks is disclosed in a. copending application of Serial No. 63 6,467, filed December 21, 1945, now Patent No. 2,597,343 of May 20, 1952. In this application there is sh wn and described a tack-like fastener of T shape which is formed from a flat strip of metal which is slit longitudinally at regular intervals, and at one end each slit then extends diagonally to the edge of the strip. The edge portion of the strip defined by the slit constitutes a leg-forming element. In the subsequent use of the strip, this leg-forming element may be bent downwardly on an axis transverse to the length of the strip until it is perpendicular to its original plane, thus forming the leg of the tack, while a section of the original strip to which the leg is attached provides the head.

In the strip shown in the with notches, mediate the leg-forming elements. These notches are utilized both in blanking out the strip and in subsequently feeding it into the driving machine, serving as indexing or feeding notches, and they also define the length of the head-forming portion of each blank.

One difficulty encountered with strips so formed is that the points of the leg-forming elements may project slightly from the edge of the strip, and hence adjacent convolutions of the coiled strip will catch or snag, sometimes interfering with the proper feeding of the strip in the driving machine.

Also, the points of the leg-forming elements of such blanks are beveled in only one direction, which sometimes produces a deflection of the leg when it is being driven.

The present invention provides a method and a fastener strip in which both these objections are overcome without any appreciable increase of cost or additional handling.

According to the present invention, a chordal segment of metal is removed from the edge of the strip in the region of each point of a leg-forming element. This provides a relief that eliminates any protruding sharp points, and at the same time produces a more symmetrical point that will have less tendency to drift or deflect sideways when being driven.

My invention may be more fully understood by reference to the accompanying drawings, in which:

Fig. l is a plan view on a larger scale of a section of strip as shown in the said Lang application, except as to the exact shape of the feeding notches;

Fig. 2 is a similar view of the strip as it is more apt to appear when produced by present methods of high speed operation, showing the slight irregularity of the points;

Fig. 3 is a similar view showing a blank prepared in accordance with my invention;

Fig. 4 illustrates a step in the actual preparation of the strip, showing the removal of chordal segments in advance of slitting;

Fig. 5 is a section through a portion of the machine for effecting such removal of segments; and

Pig. 6 is a perspective view of the finished fastener.

The strip 1, as originally designed, and which is here shown for purposes of illustration, no claim being made to it in this application, is provided at regular intervals along one edge with notches 2, and which are adapted to be engaged by the feeding of mechanism of a tool which forms, cuts and drives the cession of blanks in the strip. The strip, in being fed to the tool, moves in the direction of the arrow. Leg portions 3 are formed along the opposite edge of the strip by longitudinal slits 4 and diagonal slits S that extend from each slit 4 to the edge of the strip, the legs thus having points 6. The legs are joined to the body of the strip at their opposite ends, the joining portions being designated 7. It will be noted that notches 2 are located intermediate the length of the legs.

Practical methods for the high speed manufacture of these strips are likely to result in the points 3 projecting slightly, as shown in Fig. 2. This results in the snagging difliculties when the strip is being fed from reels into which it is coiled for use in the driving tool.

According to the present invention, a chordal segment of metal is removed from the edge of the strip in the region of each point, so that arced indentations 9 are formed at equal intervals, and the point 8 terminates in this indentation. These indents may be formed by an abrasive wheel, but they are preferably formed by a punch 10, represented in phantom lines in Fig. 3.

The indents may be formed on the otherwise completed blank. However, when using a punch, it is preferable, as indicated in Fig. 4, to form them in the blank strip before slitting, as there is then better control of the indenting operation than is obtainable after the slitting.

One method of indenting is shown in Fig. 5, wherein 11 is the bed of a die along which the strip is moved. The strip is advanced step by step along this bed, and after each movement the punch 10 operates, passing through a hole 12 in the bed of the die. The punch 10 would normally be one of several punches that operate simultaneously at different stations along the strip, so that the indenting operation does not introduce any extra handling into the manufacture of the strip.

The indents so formed avoid a condition where the points of the legs can project beyond the marginal edge of the strip. Each point is necessarily located within the width of the strip, so that snagging of the points when the strip is coiled cannot occur. The indenting also forms a bevel at So on the point of an angle opposite the slope of the slit 5. in the other words, by reason of such indents the point is beveled or sloped in two directions. Such a point has less tendency, when being driven, to deflect or drift sideways.

A "3 I have shown and described my invention specifically with reference to one particular form of fastener, but it has application to any form of fastener having one or more leg-forming elements lying in the plane of a strip and more or less parallel to the axis of the strip. It will be further understood that invention is not confined to the particular form of apparatus herein specifically described.

I claim:

l. A strip of connected staple fastener blanks comprising a ribbon of metal having a succession of partially severed leg-forming elements extending along one edge only and extending over substantially half of said metal ribbon, each leg-forming element having a sloped point formed by the severing slit and having a portion opposite the point which is connected to the body of the ribbon, the aforesaid edge of said strip having a succession of indentations therein, a portion of each indentation forming a sloped part of the point of the leg-forming element which intersects the first mentioned slope of the point.

2. A connected series of T-tack blanks comprising a ribbon of metal slitted with connected diagonal and longitudinal slits from one edge thereof at regular intervals providing a succession of pointed leg-forming elements along'one edge of the strip, said strip having a succession of indentations in said edge, the indentations being located to include the points where each diagonal slit begins so that the point of each leg starts at such an indentation and lies inside the line defining the original straight edge of the strip.

3. The method of forming a strip of connected staple fastener blanks which comprises notching one edge of a ribbon of metal to form chordal indentations at regular intervals therealong, and then slitting the said edge of the metal with connected diagonal and longitudinal slits to 3;

form a regular succession of pointed leg-forming elements, the slits beginning i 'the ends of said chordal in end of each leg-forming element tation and the indentation forms part of the point.

ted staple fastener blanks com- 1 having a succession of pointed edge containi mid portion 0 in part by sai wardly from-t of the ribbon.

References Cited in the file of this patent UNITED STATES PATENTS Jordan Sept. 4, Nilsson Feb. 20, Lewis Apr. 4, McChesney Nov. 17, Novick Mar. 2, McFaul Mar. 16, Carlile May 20, Kanuf Nov. 10, Poux Nov. 24, Ulrich Feb. 9, Lang Aug. 21, Martines Oct. 4, Jackson Feb. 7, Lang May 20,

FOREIGN PATENTS France May 29,

n each instance intermediate dentations so that the point merges into such indend by having one marginal of substantial depth in the ch leg-forming eleoint is spaced inight edge

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