| 摘要 |
Provided is a thread-forming tap for reducing machining torque and improving tool service life. A thread-forming tap (10) for plastically deforming the surface-layer section of a prepared hole to form a female thread by causing a margin section (18) of a screw thread (16) to bite into the surface-layer section of the prepared hole formed in an object to be machined, the tap being provided with a screw thread (16) formed in the shape of a male thread while a margin part (18) provided protruding in the radial direction and a release part (20) with a diameter less than the margin part (18) are arranged in alternating fashion, wherein the margin part (18) is formed in a udgeline shape with a width dimension of 0 at least at the bottom (30) of the screw thread (16), whereby the contact surface area onto the object being machined can be minimized during machining, machining torque can be reduced, and tool service life can be improved. |
