| 摘要 |
<p>Disclosed is a tapping screw which is coupled while machining a female screw and, more specifically, to a universal tapping screw which is capable of being used in all kinds of materials, such as injection molded products like synthetic resin, soft metal, and hard metal. The present invention provides a universal tapping screw and a coupling method using the universal tapping screw. The universal tapping screw comprises; a cylindrical body; a main thread; and an auxiliary thread, wherein the main thread and the auxiliary thread are arranged on the cylindrical body in two rows. The outer diameter of the auxiliary thread is 92-97% of the outer diameter of the main thread. The angle of the front flank surface of the main and auxiliary threads is 12±3 degrees. The angle of the rear flank surface of the main thread is 25±3 degrees. The angle of the rear flank surface of the auxiliary thread is 20±3 degrees. A first pitch between one main thread and one auxiliary thread and a second pitch between the auxiliary thread and the next main thread has a gap difference within±10-20%.</p> |
