| 摘要 |
1317652 Rolling threads U S M CORP 25 June 1970 [18 July 1969] 30925/70 Heading B3M [Also in Division F2] A self-locking screw 20, Fig. 11, is provided on its shank with normal convolutions 80 and with truncated convolutions 26 and 30 which produce a locking action with a mating thread 28. The shank 92 (which faces away from the head 22 of the screw) of the convolution 26 is arranged at a smaller angle 104 than normal, and the opposed, load-bearing, flank 96 is slightly thicker than normal. The truncated convolutions are produced by rolling a blank between a pair of flat dies, one at least of which has a modified thread form. Each die 34 and 36, Fig. 2, may have several of its normal thread-forming projections removed at 46. In addition to these removals, shown in Fig. 10 at 58 and 60 in die 56, and 62 and 64 in die 54, the adjacent faces 66, 68, 70 and 72 are ground away to reduce their thickness. |
