| 摘要 |
A tapping screw comprises a screw head (10), wherein one end of the screw head includes a screw rod (11) having an external screw thread. A bit (12) is integrally extended from a front of the screw rod (11). A tip portion (121) is disposed to a tip of the bit (12), and furthermore inclined diagonals of the bit have two vertical cutter surfaces (122) showing a symmetric state or an asymmetric state. Corresponding outside of the two vertical cutter surfaces (122) is upwardly an interior shrinkage cone (123). Two tapered tangential planes (124) are formed at the tip portion (121). The blades of the two tapered tangential planes (124) have a plurality of teeth (125) showing a symmetric state or an asymmetric state. The side blade of the corresponding outside of the two vertical cutter surfaces (122) further has a plurality of side teeth (126) showing a symmetric state or an asymmetric state.
|
