Importance

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Abstract

A nut for use with an elongated rod having one end anchored by a hardened resin grouting mix in a drill hole in a mine roof or other such rock formation. The nut has a body portion with a threaded bore through which the rod is advanced and a dome-shaped wall surrounding one end of the bore in radially outwardly spaced relation and an annular lip defining an opening in coaxial, axially spaced relation to the one end of the bore. A metal disc, either solid or with a central opening of smaller diameter than the bore, is positioned in covering relation to the bore and surrounded by the dome-shaped wall. As the rod is advanced through the nut, the disc is moved into contact about its entire periphery with the inside of the dome-shaped wall and rotation of the nut is transmitted to the rod to mix the resin components within the drill hole. After the mix hardens, excess torque applied to the nut deforms the nut toward the dome shape of the wall and eventually fractures the annular lip, thereby expanding the opening and expelling the disc. The torque required to fracture the nut is considerably higher when the disc is incorporated in the nut structure, thereby ensuring complete mixing of the resin components prior to fracture.

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First Claim