Process for forming bolt

Abstract

In a process for forming a bolt, a die, a rod-shaped knock-out member, and a punch are prepared. The die has opposite end surfaces, a through bore opened to one of the opposite end surfaces, and a space connected with the through bore and disposed substantially perpendicular to an axial line of the through bore. The knock-out member is disposed in the through bore. The punch is disposed so as to face one of the opposite end surfaces of the die to which the through bore is opened. A bolt precursor is fitted into the through bore of the die at the leg member, and is pressed by the punch at the head member. The leading end of the leg member is pressed by the knock-out member, and accordingly an excess material of the bolt precursor at around the leading end of the leg member, or an excess material thereof adjacent to the leading end of the leg member is deformed and flowed into the space of the die as a thinned-out portion. Thus, the bolt precursor can be flattened at the leading-end surface of the leg member. The thinned-out portion can be removed by being held between the knock-out member and the die, and does not adversely affect the configuration of a completed bolt.