| 摘要 |
976,849. Self-tapping screws. ILLINOIS TOOL WORKS Inc. Nov. 26, 1963 [Nov. 26, 1962], No. 46697/63. Heading B3N. A self-tapping screw has an entering end 2. Fig. 6, a trailing portion 4 and an intermediate portion 6. End 2 has a ridge 14 formed by flat surfaces 10 and has two slots 20 forming surfaces 22, 24, substantially at right angles, and cutting edges 28. Surface 24 is a cylindrical arc, or in a modification, Figs. 7 and 8, surface 24a is flat. The threads 18, Fig. 1, have flat crests on the intermediate portion 6, or, in the modification of Figs. 7 and 8, the thread crests are not flattened.
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