| 摘要 |
A fastener includes a shank having a point at a first end and a second, head end. A first helical thread region is formed at the first end adjacent to the point having a first helical thread having a first effective diameter. A sub-region of a second helical thread is formed within the first helical thread region adjacent to the first end. A head at the second end includes a cutting structure, the cutting structure positioned to intersect a bottom surface of the disk and the shank, the cutting structure has a square cross-section formed by four walls intersecting the disk. A third helical thread region may be provided between the first region and the head. The shank diameter in the sub-region and the first region is smaller than the other regions. |
