Claims
- 1. Safety scissors that include two elongated scissor members that are pivotally joined together at a point intermediate their ends by a pivot pin so as to divide each scissor member into a gripping section and a cutting section, the improvement being that the cutting section of each scissor member is composed of a generally dish-shaped metallic member partially embedded in a plastic matrix, said generally dish-shaped metallic member consisting of an elongated and generally flat piece of metal that includes a large recessed central portion that extends on both sides of said pivot pin for substantially the full length of said cutting section and which is surrounded by a narrow outwardly extending generally oblong rim portion, one portion of said narrow rim portion serving as the sharp cutting edge for each scissor member, said large recessed central portion having a plurality of holes therein, said holes being located on both sides of said pivot pin, plastics material both filling said large recessed central portion to a level slightly below the level of said narrow rim portion and extending through said plurality of holes to the area behind said large recessed portion so as to form a sturdy support for the entire metallic member, whereby when said scissor members are moved back and forth relative to each other the only portions which come into direct sliding contact are the generally oblong narrow rim portions.
- 2. A method of manufacturing safety scissors that include two elongated scissor members that are pivotally joined together at a point intermediate their ends so as to divide each scissor member into a gripping section and a cutting section, the method of making each scissor member comprising the steps of:
- (a) forming a blade (2) by deforming a stainless steel plate of a predetermined thickness by means of a press machine to thereby form a depressed portion (3) of predetermined depth in said blade, said depressed portion being located inwardly from the peripheral edge portions of said blade,
- (b) forming a plurality of through holes (5) in the depressed portion of said blade which permit the later penetration of synthetic resin,
- (c) forming a pivot hole (4) in the depressed portion of said blade,
- (d) forming a standard hole (6) in the undepressed portion of said blade that assists in accurate positioning of the blade in an injection mold,
- (e) preparing an injection mold that comprises a male mold (12) and a female mold (7),
- (f) shaping the blade portion forming surface (8) of the female mold (7) in a moderate arc shape,
- (g) providing said blade portion forming surface (8) of said female mold (7) with a pivot positioning pin (9) that loosely fits into said pivot hole (4) of said blade,
- (h) providing a gripping portion forming surface with a step positioning pin (11) for loosely fitting to the standard hole (6) of the blade,
- (i) causing a pressure pin 14 in the male mold 12 to press a portion close to the tip of the blade,
- (j) causing a pivot pressure cylinder (15) on the male mold which fits loosely with a tip of the pivot positioning pin (9), to press downardly upon the upwardly bulged surface side of the blade,
- (k) causing a standard pressure cylinder (17), which fits loosely with the tip of the step positioning pin (11), to press downwardly, to thereby press the blade closer to the mold,
- (l) positioning the blade properly in the injection mold and injecting a synthetic resin to thereby form the blade portion (18) and the grip portion (19) with the synthetic resin injected into the cavity,
- (m) causing the resin to penetrate into and through the depressed portion of the blade by means of the through holes (5) in the blade portion, and
- (n) curing the resin, and obtaining a scissor part wherein the sharp edge of the metal blade is properly exposed along the edge portion of the blade portion (18) made by the synthetic resin.
Priority Claims (1)
Number |
Date |
Country |
Kind |
53-135352 |
Nov 1978 |
JPX |
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Parent Case Info
This is a continuation of application Ser. No. 29,700, filed Apr. 3, 1979 and now U.S. Pat. No. 4,250,620.
US Referenced Citations (5)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1514169 |
Jun 1978 |
GBX |
Continuations (1)
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Number |
Date |
Country |
Parent |
29700 |
Apr 1979 |
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