| 摘要 |
1,209,225. Self-tapping screws; rolling threads. LAMSON & SESSIONS CO. 17 May, 1968 [18 May, 1967], No. 23704/68. Headings B3M and B3N. [Also in Division F2] A self-tapping screw 40, Fig. 5, or a locking bolt 45, Fig. 6, have circumferential axiallyspaced deformed areas 43, 49, which produce locking of the screw or bolt when screwed into a workpiece. Screw 40 has axially deformed thread-swaging areas 25 on its leading end 20a. In a modification, the locking part of the thread 20 is omitted, or locking threads are provided along the whole of the thread 20b. The threads are rolled on to the screws by a pair of reciprocating flat dies, Fig. 7 or Fig. 9, or in a modification, rotating cylindrical dies are used. |
