| 摘要 |
A screw includes a shank, a first and second thread part extending helically on a circumference of the shank, and a second thread part extendin g helically on the circumference of the shank between the head and the first thread part. The first thread part includes a first flank facing the head an d a second flank facing away from the head and intersecting the first flank at a ridge, wherein the first thread part comprises a plurality of blade sections and rectilinear chamfered sections disposed alternately along an outer edge of t he first thread part. |
