US2751807A - Thumb tack having curved shank and bent sheet metal head - Google Patents

Description

June 26, 1956 K. J. s. HARRE THUMB TACK HAVING CURVED SHANK AND BENT SHEET METAL HEAD Filed Dec. 13, 1951 INVENTOR United States Patent THUMB TACK HAVING CURVE!) SHANK AND BENT SHEET METAL HEAD Kurt Johan Stausgaard Harre, Bromsten, Sweden Application December 13, 1951, Serial No. 261,517

2 Claims. (Cl. 85-16) This invention relates to thumb tacks and the main object of the invention is to provide a thumb tack which is easily removable after insertion without the use of tools or finger nails and without injuring the paper or like through or into which the tack is pressed.

A further object of the invention is to provide a thumb tack in which the pin may be guided by the head during insertion so that the pin will not bend or get loose from the head.

A thumb tack according to the invention is mainly characterized by the combination of an elongate sheet metal head, one end portion of which is bent sharply upwards to form an obtuse angle with the plane of the other end portion, and a curved pin protruding from the bottom side of one of said end portions of said head in a manner to have the center of its curvature on a fulcrum line formed in the place where said end portions merge into each other, the point of said pin being located above an imaginary extension of the plane of said other end portion of said head.

It will be clear that such a thumb tack offers the advantages that the pin will be guided when forced through or into an object because the head may then rest on said object and tilt about the fulcrum line, thereby preventing the pin from being subjected to bending forces, and further the pin may be completely extracted, by simply pressing down the remote end portion of the head, the pin then also being guided so that the hole in the object formed by the pin will not be enlarged or injured by lateral movements of the pin.

Two embodiments of the invention will now be more particularly described with reference to the drawing, wherein:

Fig. 1 is a perspective view of the one embodiment of the thurnb tack according to the invention,

Fig. 2 is a perspective view of the other embodiment of the thumb tack,

Fig. 3 is a side view showing a thumb tack according to the invention in the position where the pin of the tack is just to be pressed down into an object or has just been extracted from said object, and

Fig. 4 is a side view showing the tack when pushed through a paper and into a drawing table or like support.

It is obvious that Figs. 3 and '4 apply to both embodiice ment of the tack according to Figs. 1 and 2 because these embodiments are equivalents as regards general construction. Like references in all figures also designate like parts.

Referring to the drawing, the thumb tack comprises an elongate metal plate 1 forming the head of the tack. One end portion 2 of said metal plate is bent sharply upwards to form an obtuse angle with the plane of the other end portion 3, a fulcrum line or edge 4 transversing the head being thus formed on the lower side of the head in the place where said end portions 2 and 3 merge into each other. The one end portion 3 of the head 1 is provided with a curved pin 5 protruding downwardly from the lower side thereof. The curvature of the pin 5 is so chosen and arranged that the center thereof coincides with a point on the fulcrum line 4 and the pin 5 is of such a length that the point 6 thereof is located slightly above an imaginary extension of the plane of the remote end portion 2 of the head 1 represented by the supporting surface 7 in Fig. 3.

The pin of the tack may either be a separate one riveted to the head 1 as the pin 5 in Fig. 1, or it may form an integral part of the head being punched out therefrom as in Fig. 2, wherein the pin has been designated 5' and the slot left in the head 1 by the punched out pin 5' is designated by numberal 8.

It will appear from Fig. 4 how the pin 5 of the tack penetrates through a paper 9 and into a support 10 along a curved path and it will also be seen that the tack may be easily removed by applying a pressure to the upwardly bent end portion 2 of the head 1 because the head will then tilt about the fulcrum line 4, thus causing the pin 5 to follow the same curved path as when being inserted.

I claim:

1. In a thumb tack the combination of an elongated rigid sheet metal head, one end portion of which is bent sharply upwards to form an obtuse angle with the plane of the other end portion, and a curved pin protruding from the bottom side of one of said end portions of said head in a manner to have the center of its curvature on a fulcrum line formed in the place where said end portions of said head merge into each other, the point of said pin being located slightly above an imaginary extension of the plane of said remote end portion of said head.

2. A thumb tack as claimed in claim 1, wherein said pin forms an integral part of said head and is punched out therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 641,326 Riedmiller Jan. 16, 1900 1,560,221 Downey Nov. 3, 1925 1,910,688 Goodstein May 23, 1933 2,550,549 Goodstein Apr. 24, 1951 FOREIGN PATENTS 355,922 Great Britain Sept. 3, 1931

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