| 摘要 |
A threaded fastener (11) of the type comprising: a shank (12), a radially enlarged head (13) at one end of the shank (12), an external screw thread (14) on at least a part of the shank, and a bore (15) extending through the head (13) and into the threaded part of the shank, at least the threaded part of the shank being radially expandable into threaded engagement with the wall of a suitable unthreaded bore in a workpiece in which the threaded part has been inserted, the fastener (11) thereafter being removable by unscrewing it from the workpiece bore; characterised in that the expandable part of the shank is provided with a plurality of radially extending lugs (21) or other protrusions thereby to resist unscrewing of the fastener (11) from the workpiece bore.
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