| 摘要 |
PROBLEM TO BE SOLVED: To provide a new and improved screw having a thread shape capable of strengthening its performance as the screw when it is screwed in a nut or a workpiece. SOLUTION: This screw comprises a threaded body (11) for demarcating a shaft (A) and a driver head (10). The threaded body (11) includes a thread profile (15) in an axial direction cross section and comprises a plurality of zones. The zones are formed of flat trailing surfaces (29) in a direction in which the screw advances in a processed object. The trailing surfaces have a first zone (I) constituting a first angle (α) to the diameter of the body portion (11), a second zone (II) formed of a rounded leading surface (31) constituting an existing radius (22), and the tip (30) of the thread. The flat front surface of the front end constitutes a second angle (β) to the diameter of the body portion, and the rounded leading surface (31) includes a third zone (III) which is brought into contact with the top end (30) in a prescribed distance (34) to a continuous the thread depth (19) of the screw. COPYRIGHT: (C)2004,JPO&NCIPI
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