Patent ID: 8147343
Filing Date: 2012-04-03
Classification: B23G,Y10T

Abstract:
1. A tap for cutting a female screw on a work piece by rotating about a center axis, comprising: a screw portion having a chamfer angle portion and a complete thread portion provided next to the chamfer angle portion, a body provided next to the screw portion, a groove recessed on an outer peripheral surface of the screw portion, a projection having a cylindrical shape and integrally formed with the screw portion in a manner extended from a top surface of the screw portion; a center hole recessed on an outer end surface of the projection about the center axis; and an intake hole extending inside the body from a rear end surface of the body and through an inside of both the screw portion and the projection in such a way that it extends over the top surface of the screw portion until close to but not reaching the center hole, wherein the intake hole has a circular cross section with a diameter smaller than a diameter of the body and larger than a groove bottom diameter of the groove, and has an opening which opens to an outside at the groove; wherein a first end portion of the opening of the intake hole at a top side of the screw portion is positioned at the projection while a second end portion of the opening opposite to the first end portion is positioned at about a middle area of the screw portion; and wherein chips generated in cutting are aspirated from the opening by performing air intake through the intake hole.