| 摘要 |
The present invention provides a screw comprising of a head, a shank under the head in a whole body, and a thread helically built upon the outside trunk of the shank; wherein, said thread projected from the circular trunk of the shank is consisted of an upper flight, a low flight, and a peak on the joint line of the upper and low flights, and an even number of axial slots formed on the thread. The feature is that every axial slot is bevelled with a back angle to form a sheared section from the upper flight to the low flight to form a cutting edge for facilitating to rapid fastening with smaller tapping torque as tapping in.
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