Osg Corporation

Kentarou Norimatsu

Jiro Osawa

Tasuku Itoh

Takayuki Nakajima

Takayuki Matsushita

A removable tip type rotary tool is provided in which a rotation stop key and a key groove each having a triangular shape are disposed on opposing surfaces of a body and a tip concentrically attached to a leading end portion of the body in a removable manner. A pair of side surfaces of the rotation stop key and a pair of side walls of the key groove are brought into surface contact by mounting screw. An angle for each of the pair of the side surfaces and the pair of side walls is between 60 to 100 degrees, a groove bottom of the key groove is rounded with a radius from 1.5 to 2.8 mm, corners of opening edges on both sides of the key groove and corners of both base-end side portions of the rotation stop key are rounded with radiuses, respectively, from 1.5 to 2.8 mm.

Removable tip type rotary tool

A following margin of a following flank of an external thread is shifted more in a screw-rotation direction than a leading margin of a leading flank. Thus, during biting, the following margin bites first, thereby suppressing a force that pushes back a tap and reducing a tapping torque. Because margin portions can be disposed parallel to an axis of a thread forming tap, working is easy and manufacture can be performed inexpensively. When, in forming an external thread by grinding by a grinding abrasive, an inclination angle of the axis of a tap blank and an abrasive axis of the grinding abrasive is equal to a lead angle of the external thread, the margins are formed symmetrically across a root. On the other hand, if the inclination angle is made greater than the lead angle, the following margin can be shifted in the screw-rotation direction, enabling manufacture to be performed as easily and inexpensively as in a conventional case.

Growing community of inventors

Toyokawa, Japan

Kentarou Norimatsu