Abstract: 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.

Abstract: 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.

Abstract: A spiral tap is disclosed having a thread portion having an external thread, spiral flutes which is fluted in the same direction as a cutting/rotating direction, as seen in a direction away from a shank side, to divide the external thread, and cutting edges formed along the spiral flutes; the thread portion including a full thread portion having a fixed outer diameter, and a chamfer portion decreasing in outer diameter toward a tap end; the chamfer portion being screwed into a prepared hole to cut an internal thread on an inner circumferential wall of the prepared hole and to discharge chips along the spiral flutes toward the shank; the chamfer portion having an external thread with screw threads which is formed such that outer circumferential portions are removed, at a linear line for cutting as seen from a direction perpendicular to a cross-section involving an axis O, from the screw threads having the same dimension as that of the full thread portion; and the linear line intersecting the axis O at an incli

Abstract: 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.

Abstract: A cold forming tap and a method of manufacturing the cold forming tap. Since the following side margin M2 of the following side flank (22b) of a male screw (22) is deviated from the leading side margin M1 of the leading side flank (22a) thereof in a screw-in rotating direction as shown in FIG. 2 (a), the following side margin M2 bites precedently in biting and a force to push back a tap is suppressed to reduce a tapping torque. Also, a margin part M may be formed parallel with the axis of the cold forming tap (10), it can be easily manufactured at low cost Namely, when the male screw (22) is ground by a grinding wheel (32), a margin can be symmetrically formed with respect to a bottom as shown in FIG. 2 (b) when the tilt angle ? of the axis of a tap material (30) relative to the centerline of the grinding wheel (32) is the same as the lead angle of the male screw.