Patent ID: 7377732
Filing Date: 2008-05-27
Classification: B23G,Y10T

Abstract:
1. A thread mill that is to be moved along an orbit path about an axis of a preparation hole being formed on a workpiece and having a chamfer at an opening edge while being rotated in one rotating direction about an axis of the thread mill in the preparation hole, for forming an internal thread in an inner circumferential surface of the preparation hole, said thread mill comprising: a cylindrical main body including (a) annular protrusions, formed on an outer circumferential surface thereof and having a profile corresponding to the internal thread to be formed on the workpiece with no lead, and (b) at least one spiral flute formed to divide the annular protrusions to provide at least one cutting edge along said spiral flute, wherein said spiral flute extends in a rotation direction opposite to said one rotating direction of said main body as viewed in a direction from a proximal end toward a distal end of said main body.