Die for rolling de-pitched prevailing-torque screw - has two equal-pitch undulating sections separated by greater-width parallel crest

摘要

The die is intended for use in conjunction with a complementary die for rolling screw thread of a de-pitched prevailing-torque screw bolt and is of the type having a first and a second section with parallel cruciform-pitch hill (5)-and-dale (4) corrugations, the corrugations of the first section being out of phase relative to those of the second section. The two sections are separated by a region (6) which is parallel to the corrugations and which is preferably formed as a rib (6) whose width is greater than that of each hill (5) of the corrugations. The thread produced by these dies has no abrupt interruption.