| 摘要 |
A fastener for locking two or more sheet sections together comprises a shaft tapered at one end and having a driving head at the other end with a relatively coarse thread running from the tapered end towards the head and a relatively 10 fine thread between the coarse thread and the head. The fine thread has a pitch which is approximately equal to the thickness of the sheet sections and extends from the head for from two to six threads. roof GU R7r |
