| 摘要 |
An improved mine roof bolt is constructed of pre-tensioned, multi-strand steel cable. The bolt head is constructed of a hexagonal-or other drive-headed collar having an internally tapered frusto-conical bore therethrough, and a tapered plug having a frusto-conical outer surface that engages the frusto-conical inner surface of the drive collar. The tapered plug has an internal bore essentially concentric with the outer frusto-conical surface, and is adapted to fit over the multi-stranded steel cable, the hexagonal head drive collar fitting over the tapered plug such that pressing the tapered plug and steel cable into the inner frustoconical bore of the hexagonal-head drive collar causes serrations on the internal bore of the tapered plug to be urged down against, and bite into, the steel cable, resulting in a solid hexagonal head for the cable bolt. The tapered plug is in actuality, a pair of essentially identical diametrically opposed semi-frusto-conical tapered sections that more easily compress together to bite into the multi-strand steel cable. The improved mine roof bolt is intended for use in passive-type mine roof systems.
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