Self-tapping screw thread structure

Abstract

A thread structure for a self-tapping screw is disclosed to reduce cutting resistance. It comprises: a shank body with a first end having a cap with a drive groove; a second end having a starting end with a tapping portion having at least one cutting edge; and, starting from the starting end, a first thread, a second thread, and a third thread sequentially arranged therefrom. The second thread has the same first helical direction as the first thread, and each thread of the second thread has a plurality of notches at its crest, with the notches of adjacent threads being misaligned and staggered, each notch having an included angle; and the third thread has a second helical direction opposite to that of the first and second threads. This design improves the tapping efficiency of the self-tapping screw.

Claims

1. A threaded structure of a self-tapping screw, comprising: a rod having an axial centerline passing through its center, a first end of the rod having a cap having a drive groove, a second end of the rod having a starting end having a tapping portion having at least one cutting edge; and a first thread protruding around the rod having a first helical direction and extending from the starting end toward the first end of the rod. A second tooth, circumferentially protruding from the rod body, starting from the starting end, is located behind the first tooth. The second tooth has the same first helical direction as the first tooth. Each tooth of the second tooth has a plurality of notches at its tip. The notches of adjacent teeth are misaligned and staggered, and each notch has an included angle. A third tooth, circumferentially protruding from the rod body, starting from the starting end, is located behind the second tooth. The third tooth has a second helical direction opposite to that of the first and second teeth.

2. The thread structure of the self-tapping screw as described in Request 1, wherein, The number of teeth in this first dental part is 4 to 5.

3. The thread structure of the self-tapping screw as described in Request 1, wherein, The tips of each tooth in the first tooth section are formed with serrations.

4. The thread structure of the self-tapping screw as described in Request 1, wherein, The number of notches on the top of each tooth in the second part is 2 or 3.

5. The thread structure of the self-tapping screw as described in Request 1, wherein, The included angle of the missing corner is 90°.

6. The thread structure of the self-tapping screw as described in Request 1, wherein, Each of the included angle endpoints is connected to the center of the rod to form a virtual dividing line, which divides the included angle into a front angle and a rear angle. Depending on the rotation direction of the self-tapping screw, the front angle contacts the object being locked first, before the rear angle.

7. The thread structure of the self-tapping screw as described in claim 6, wherein, The front angle is 65°±3°, and the rear angle is 25°±3°.

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