| 摘要 |
A screw includes a head and a shank provided with screwing threads and cutting threads. Each thread of the screwing threads and each thread of the cutting threads are positioned to form an angle phi so that the screw can smoothly move in a wooden object by means of the screwing threads in screwing in the wooden object, lowering screwing toque by means of the cutting threads, and thus enhancing locking force of the screw against the wooden object. |
