| 摘要 |
This invention relates to a fastener, which expands by the insertion of an expanding member, preferably a screw through an engageable hole of the fastener. The fastener comprises a substantially flat head and two expandable legs. The head has an upper side and a lower side, preferably separated by a gap. The fastener has a hardness within a range which improves considerably the pulling force and allows the head of the fastener to be bowable upon applying said force on the expanding member, thus resulting in a gradual rather than abrupt failure. The engageable hole may be round or oblong. Additional engagement may be provided at lower portions of the fastener for improving pulling force and/or prevailing torque. Further, an elastic body may be integrally molded at least at the lower side of the head of the fastener, and preferably throughout the head of the fastener.
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