| 摘要 |
1,223,462. Making screws. U.S.M. CORP. 23 April, 1968, No. 19070/68. Headings B3A and B3H. [Also in Divisions B5 and F2] A self locking screw 12 has a cavity 16 formed in the thread and a lip 22 is formed in the cavity wall, the lip locating a resilient locking pellet 14 in the cavity. The centre of the cavity coincides with a root of the thread and the cavity is formed by a punch 20. A further punch 30 having a concave surface 26 is then applied to the threads to form a lip 22 at each portion of the cavity wall which coincides with the thread crests on opposite sides of the cavity. The deformation of the threads adjacent the cavity is corrected by a thread re-forming punch and the pellet of nylon is then compressed into the cavity by a punch. The pellet is finally formed with threads by a punch. In a modification, the centre of the cavity coincides with a crest of the screw thread and the lip forming punch has a convex surface.
|
