Indexable thread forming tap

摘要

An indexable thread forming tap including: a body in a shaft shape; and a tip concentrically and detachably attached to a leading end portion of the body by screw-fastening and rotationally driven around an axial center along with the body for rolling of a female thread, the body being disposed with a screw hole concentrically to the axial center such that a screw shaft disposed on the tip concentrically to the axial center is screwed into the screw hole for the screw-fastening, a leading end surface of the screw shaft being pressed against a bottom surface of the screw hole into close contact with each other by the screw-fastening to integrally fix the tip to the body without the leading end of the body abutting on the tip, the body being disposed with a restraining hole concentrically to the axial center.

主权项

1. An indexable thread forming tap comprising:
a body in a shaft shape; and a tip concentrically and detachably attached to a leading end portion of the body by screw-fastening and rotationally driven around an axial center along with the body for rolling of a female thread, the body being disposed with a screw hole concentrically to the axial center such that a screw shaft disposed on the tip concentrically to the axial center is screwed into the screw hole for the screw-fastening, a leading end surface of the screw shaft being pressed against a bottom surface of the screw hole into close contact with each other by the screw-fastening to integrally fix the tip to the body in a state where a predetermined gap is provided between a leading end of the body and the tip, the body being disposed with a restraining hole concentrically to the axial center such that a restraining portion disposed on the tip concentrically to the axial center is fitted into the restraining hole to position the body and the tip concentrically to the axial center, an outer diameter of the leading end surface of the screw shaft brought into close contact with the bottom surface of the screw hole being within a range of 30 to 55% of a machining diameter of the tip, and a nominal diameter of the screw hole and the screw shaft being within a range of 48 to 66% of a machining diameter of the tip.