| 摘要 |
A self-drilling screw is provided which is suitable for use with both relatively thick metal plates and relatively thin metal sheets. The screw is formed from a blank 1 which includes a shank 2 extending between a head 3 and drilling tip 4. The shank 2, adjacent the head 3, is formed with a frusto-conical enlargement 8. A thread 10, when formed in shank 2, is extended into enlargement 8 so as to create a final part 11 of the thread which, in use of the screw with sheet metal 12, distorts the sheet metal such that it firmly locks onto the enlargement 8. A shallow recess 6 is provided in the underside of head 3 surrounding the frusto-conical enlargement 8.
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