SPLIT PIN HOLE WORKING METHOD OF BOLT OR THE LIKE

摘要

PURPOSE:To prolong a punch life and to disuse a burr removal by forming a recessed groove at least on a one face of the pin hole position simultaneously with the drawing work of the lower bore part of a blot thread and by piercing the pinched hollow groove part with a punch in the split pin hole work of a bolt. CONSTITUTION:A hollow groove is formed at least on one face of the pin hole part with the punch projection of a jig in case of performing a drawing work of the thread lower bore part of a bolt by a jig. A pin hole is pierced with abutting a punch to the hollow groove. The punch life is prolonged with the concentration of the stamping stress in the stamping direction without working of the lateral stress to the punch by the hollow groove. The chamfering of the pin hole after piercing is disused as well with the display of the chamfering effect by the hollow groove.