Cutting head screw is formed by conical section and threaded section, whereby surface of conical section has means to cut out material and length of conical section is approximately a third to a half the overall length of screw

摘要

The cutting head screw is formed by a conical section (1) and a threaded section (2), whereby the surface of the conical section has means to cut out material and the length of the conical section is approximately a third to a half the overall length of the screw. The angle between the longitudinal axis of the screw and the surface of the conical section comes to between 10 and 40 degrees.