| 摘要 |
1,271,374. Drills. IMPERIAL CHEMICAL INDUSTRIES. 27 April, 1970 [18 Feb., 1969], No. 8656/69. Heading B3C. [Also in Division F2] An anchor bolt comprises an end portion 12 of rectangular cross-section, twisted to form a left-handed archimedean screw and having a cutting edge 16: The bolt also has a shank 11 and a threaded portion 13 at its other end to receive a nut securing a pressure plate in position once the bolt has been secured in a bore. For example, for securing the roof of a mine a cartridge of mixable and settable substances having been inserted in the bore, the bolt is rotated and forced axially into the bore the cutting edge rupturing the cartridge and the screw mixing them together, whereafter the substances set to secure the bolt in position. The screw may be slotted to provide additional keying for the hardened substances and a washer 17 is secured in position to prevent the substances from becoming displaced along the shank. |
