20140314522 | Screw - A screw includes a shank and at least one end cutting groove. The shank includes a lower section disposed near an insertion end thereof and an upper section disposed near a head end thereof. The lower section has triangular transverse cross sections, and the upper section has circular transverse cross sections. A first thread is disposed on the lower section of the shank, and a second thread is disposed on the upper section of the shank. A non-threaded section is disposed between the lower section and the upper section of the shank. An outer diameter of the non-threaded section is larger than an outer diameter of the upper section. The end cutting groove is formed in the lower section of the shank, and an included angle between 3 and 9 degrees is formed between an extending direction of the end cutting groove and a longitudinal axis of the shank. | 10-23-2014 |