| 摘要 |
The present invention discloses a screw for use with very thin sheet metal. The screw has a head and a shank which has a first and relatively very short tapered section and a second, longer, substantially cylindrical section. The first section attaches to the underside of the head on one end and to the cylindrical section on the other. The first section is broader at the end attached to the head and carries two or fewer turns of threads. The second section of the shank carries uniform threads that are continous with the threads on the first section. The underside of the head also has locking serrations which are triangular, having an included angle of 28 degrees and gradually increase in height at slope of 8-10 degrees with a length of approximately twice their height at their highest point. |
