| 摘要 |
1479600 Screws; washers BRITISH SCREW CO Ltd 24 Oct 1974 [13 Nov 1973 22 Jan 1974] 52741/73 and 02941/74 Heading F2H [Also in Divisions B3 and B4] A threaded fastener for connecting at least two contacting sheets or plates 15, 16 of known thicknesses has a head 10, self-tapping threaded portion 12 below the head, a plain cylindrical portion 13 below the threaded portion 12, and a pointed tip section 11, the cylindrical portion 12 having a length at least as great as the sum of the sheet thicknesses, the maximum cross-sectional dimension of the tip section 11 being not less than the core diameter but less than the outside diameter of the threaded portion 12, and the maximum cross-sectional dimension of the cylindrical portion 13 being less than the maximum cross-sectional dimension of the tip section 11. The fastener is used to join sheet metal members, and is driven through them by a cartridge-operated tool so that the tip section 11 punches a flanged hole in the sheets 15, 16, but the threaded portion 12 is not forced into the hole. The fastener is then rotated so that the threaded portion forms a thread in the hole and the fastener is finally tightened. A plastics washer 18, which may be used in conjunction with a metal washer 17, is deformed to seal the fastening. |
