| 摘要 |
A screw driver ( 40 ) having a bi-tapered driver tip fits into a bi-tapered screw driver tip receiving socket in a screw ( 42 ). The outer taper on the driver tip and the outer taper in the driver tip receiving socket in the screw are complementary to each other and each have a taper angle of substantially about 40°-50°, with substantially about 45° being the preferred angle. The inner portions of the driver tip and the driver tip receiving socket are also complementary portions. They have a taper angle of substantially about 25°-35° with substantially about 30° being the preferred taper angle. The screw driver tip and the tip receiving socket have four grooves spaced substantially 90° apart and four ridges space substantially 90° apart. The ridges on the screw driver tip enter into the grooves in the screw driver receiving socket in the screw and the ridges in the socket in the screw are received with the grooves formed in the screw driver tip. This construction of the screw driver tip and the screw driver tip receiving socket in the screw is closely patterned after the well-known "Phillips" screw and screw driver.
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