Boeul bit nibeu head of the molding tool (頭部) or nut (成形 工具 用 Nib)

摘要

The present invention relates to a nib for the forming bolt heads or nuts. Nib(7) to be used in a forming tool comprises a segment combination nib(2) composed of a plurality of nib segments(1), and a regular polygonal hole(6), which is formed at the inside of the nib. Stress absorbing hole(9) is formed on the edge portion of the inner circumference of the bush(3) or the outer surface of the segment combination nib(2). Since the stress absorbing hole(9) serves to absorb stress concentration applied to the nib segments(1), the nib(7) is not liabale to develop flaws as in previous nibs and stopping of the machine for exchange of the nib(7) is scarcely needed. Accordingly, is improved productivity.