| 摘要 |
A screw fastener includes a head portion, a shaft portion extending from the head portion, and at least one locking serration. The shaft portion has a helical thread structure defining a thread part and a root part. The locking serration protrudes from the root part of the helical thread structure. The locking serration is configured and arranged to allow rotation of the shaft portion in a fastening direction and to restrict rotation of the shaft portion in a non-fastening direction upon engaging with a workpiece.
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