Thread-forming screw

摘要

A tool for forming an internal thread in concrete, rock or the like has a clamping part (1), a shank part (2), a guide part (3) with a thread (4) arranged on it, and a thread run-out part (5) which is formed with a slight taper and extends over the rest of the tool length and via which the thread (4) continues. The ratio of the outside diameter (da) to the core diameter (dk) of the guide part is about 1.25 to 1.5, and the ratio of the outside diameter (da) to the pitch (p) of the thread (4) is about 1.5 to 1.6. The thread (4) is provided with cutting teeth.