| 摘要 |
The present invention relates to a thread rolling tap for making female threads by plastically working the material, and more specifically, to a thread rolling tap comprising a threads part having threads along the outer surface, a chamfer part tapering into a curved shape, and a parallel part extending from the chamfer part, wherein the threads part further comprises a plurality of protruding parts, which protrude, along the threads, by a predetermined distance from the threads, and which form female threads by plastically working the material by applying pressure to the surface of the through-hole of the material; the closer the protruding parts get to the parallel part, the smaller the amount of plastic work done by each of the protruding part, and thus the resistance to plastic working, which is applied to each of the protruding parts of the chamfer part, is made uniform; and the crests of the chamfer part are formed longitudinally round, thereby minimizing the flow resistance of the material, whereas the crests of the parallel part are formed longitudinally flat, thereby facilitating the supply of processing fluids and reducing the frictional resistance between the female threads and the thread rolling tap, which is due to the springback of the completed female threads. Thus, the lifespan of the thread rolling tap is lengthened. |
