Self-locking screw with axially displaced thread - is rolled by special two=part die with two thread sections at same pitch

摘要

A shank (1) of a self-locking screw has its threaded portion divided into two parts (3, 5)by a groove (2) which is slightly deeper than the depth of the thread. The threads in both sections have the same pitch but are displaced longitudinally with respect to each other. When the screw is screwed into a nut or tapped hole so that both threaded sections (3, 5) are engaged, the groove (2) is subjected to a tensile force which locks both sections of thread (3, 5) in their mating threads. The threads in the screw are rolled by a two part die which provides the required axial displacement.