Lightweight threaded fastener and thread rolling die

摘要

The present invention is to a lightweight threaded bolt type fastener having a shank with a large diameter portion and small diameter portion connected by a transition portion; a thread is roll formed on the small diameter portion and terminates in a run-out section where the thread gradually decreases in root depth and width and with the run-out section being of minimal axial length and being located closely adjacent the transition portion to produce a run-out zone of minimal axial length. A rolling die for forming the thread with minimal thread run-out having ridge segments with tapered end surfaces for providing the run-out thread with an end wall parallel to the transition portion and a method of making the bolt type fastener.