| 摘要 |
<p>790,483. Anchor-bolts. WEGHUBER, W. Jan. 3, 1955 [Jan. 2, 1954], No. 140/55. Class 89(1) [Also in Groups X and XXII] Rock-layers in mine-tunnels &c. are stabilized by anchor-bolts, the heads of which form drills for boring the holes to receive the bolts. In one arrangement, the bolt comprises a shank 1, Fig. 2, with head 2 and cutting-edges 4, and is secured in its bore by a sleeve 5, the slit end of which is expanded by relative axial-movement between the sleeve and bolt-head caused by turning a nut 10 engaging threads at the free end of shank 1. The sleeve may have a removable extension 3 to save material, and the shank may have an axial-bore with radially-extending branches to aid removing the dust during drilling, and through which cement may be applied to fill the bore about the bolt and sleeve. In another arrangement, the axial-bore is extended by a tapered-bore in the head, and the bolt is secured in its bore by driving a pin to open the taperedbore and thus expand the head. Alternatively, such expansion may be caused by detonating an explosive in the axial-bore. In yet another embodiment, shank 1, Fig. 7, has formed thereon or secured thereto projections 21 which may be helical, and the bolt is secured in the bore 19 by cement applied through bore 9 in the shank and holes 13. The cutting-edges may be brazed on the heal 2 or be cut therein, the drill-life being sufficient to cut one bore only.</p> |
