NUT AND INTERMEDIATE PRODUCT THEREFOR

摘要

A nut consists of integral metal material and has a female screw thread formed with a rolled tap in a screw hole that opens substantially perpendicularly to an end surface of one end of the nut. A lead thread is located at an opening end of the screw hole and has a shape including a concave curved portion and a linear tapered portion that are continuous with each other, and extend along the overall periphery of the opening end of the hole. Due to the special lead thread, the first thread formed by the rolled tap adjacent to the lead thread will not have a concave groove along its crest, although subsequent threads have such a concave groove along the thread crest as a characteristic of thread formation with the rolled tap. Such a thread structure avoids cross-threading when a bolt is engaged in the nut.