Assembling of drive shaft and vehicle

摘要

The screw (3) includes a shank (31) and a head portion. The shank portion has a continuous spiral screw thread (32) with a number of turns. Each of all or some of the turns of the screw thread is formed with from two to six adjacent concave facets (321) along the cutting line. Each of the concave facets has a radial width ranging from about 60 to 120 degrees. Each pair of the adjacent concave facets forms a pointed corner (322) at the cutting line.