Tap for forming thread, has screw-shaped external thread with alternately linked margins and reliefs for forming an internal thread by plastic deformation upon having the margins bite into a surface of the prepared hole of a workpiece

摘要

The tap (1) has a screw-shaped external thread (3) with alternately linked margins (5) and reliefs (6) for forming an internal thread by plastic deformation upon having the margins bite into a surface of the prepared hole of a workpiece. A helix of the margins is in a direction opposite the direction of the helix of the external thread itself.