GB467169A - Improvements in set screws - Google Patents

Abstract

467,169. Locking set-screws. STANDARD PRESSED STEEL CO. Dec. 6, 1935, No. 33861. Convention date, April 26. [Class 89 (i)] A set-screw, particularly of the hollow and headless type, has at least a portion of its thread transversely expanded or upset at the apex, the said expanded portion being adapted to jam in a normal thread in which the said screw is mated thereby relatively to lock the said threads. A set-screw, Fig. 1, has threads 1 at the inner working end of normal formation, and a relatively small section 2 of thread at the outer end is subjected to a knurling operation by which it is serrated with the formation of beads on the inner and outer faces of the thread, whereby the threads are increased in width ; this thickening is limited to a narrow area at the peripheral edge of the thread. In a modification, Fig. 3, the serrations are inclined to the longitudinal axis of the screw, extending from the lower to the upper face of the thread in the unscrewing direction ; the knurling results in the formation of beads on one side only of the serrations, namely that side which slopes inwardly towards the rising portion of the helix ; the fin and beads formed on the lower face of the thread may be removed by machining, so that the thickening occurs on the upper face only. The serrations may have the form of backwardly directed saw-teeth ; alternatively, serrations may be dispensed with, the thickening being effected by a smooth-faced roller. The Specification as open to inspection under Sect. 91 was not limited to the application to set-screws.