Asymmetrical screw device

摘要

In order to prevent the loosening of screws due to bending of the screw thread during tightening, the invention provides an asymmetrical screw device which is distinguished in that, upon the combination of a pair comprising a male or external thread and a female or internal thread of the same nominal diameter, but having mutually different bending strengths in the thread region, the gap between the flanks of the screw thread of external and internal threads is such that it increases progressively in the direction of the side with lower bending force. Thus, deformation of the thread during tightening results in punctiform abutment of the thread flanks becoming large-surface-area abutment, and the retaining forces are markedly increased. <IMAGE>