| 摘要 |
1,175,485. Screw sockets. UNITED-CARR Inc. 20 Feb., 1968 [15 March, 1967], No. 8193/68. Heading F2H. An insert adapted to be fixedly inserted into a bore 16 in a wooden workpiece comprises a hollow tubular shank 2 with a radially extending flange 3 and a plurality of fins 5, each of the fins having a sharp leading edge 8 facing away from the flange and a trailing edge which merges with the trailing edge of an adjacent fin at the apex 12 of a V-shaped flute 13, the extended diameter of the flute portion being less than the shank diameter between the apices of the flute and the flange. The insert is made in metal or plastics material. In the embodiments described the shank is internally screw-threaded and, to provide increased resistance to rotation, the flange may be formed with a plurality of prongs spaced from the shank and extending towards the fins, Fig. 6 (not shown), or longitudinal lugs may be formed on opposite sides of the shank adjacent the flange, Figs. 7-10 (not shown). Narrow gaps between portions of leading edges (which intersect in a sharp point 8) provide for displaced material to be clamped between opposed surfaces of co-operating pairs of fins, e.g. 6, 7; while more is jammed in shallow pockets 14 at the apex of each flute 13. Wedge shaped recesses between pairs of fins have a similar function in the embodiment of Figs. 8, 10. |
