Roof bolts for use in mines, a method for their production and a method for their installation

A method for the production of nuts for roof bolts which method comprises:

• (i) casting a molten metal in the shape of a nut;
• and
• (ii) tapping a thread through the cast metal in a manner such that the central axis of the tapped hole is offset from the central axis of the nut by from 0.015 to 0.50 inches.

A system for roof bolting, said system comprising a means for rotating a roof bolt said means including a chuck for holding the end of the roof bolt, said bolt comprising a shaft having a central axis and wherein the chuck is adapted to rotate the bolt so that the shaft of the bolt rotates about an axis which is offset with respect to the central axis of the shaft whereby the shaft is caused to describe a circle of diameter greater than its own diameter.

A method for the installation of a roof bolt in a mine, said bolt comprising a shaft with a longitudinal axis, which method comprises inserting the roof bolt into a drilled hole and employing a chuck to rotate the bolt, said chuck being adapted to rotate the bolt so that the shaft of the bolt rotates about an axis which is offset with respect to the longitudinal axis of the shaft and thereby describes a circle of diameter greater than its own diameter.

A nut suitable for use with roof bolts of the type having a threaded end portion said nut comprising a body having a tapped hole and where the central axis of the tapped hole is offset with respect to the central axis of the body of the nut, the amount of offset being from at least 0.015 to 0.50 inches preferably from about 0.02 to 0.25 inches.

A roof bolt and nut in screw threaded engagement, said bolt comprising a shaft with a longitudinal axis, for insertion in a hole drilled in a mine roof and a threaded portion engaged by the nut whereby the bolt may be rotated and the nut is releasably locked in screw threaded engagement with the bolt so that the bolt can be rotated by means of the nut and above a selected torque the nut will break out, and wherein the nut is offset with respect to the longitudinal axis of the shaft of the bolt so that when the bolt is rotated by means of the nut, the bolt is caused to describe a circle of greater diameter than its own diameter, the amount of said offset being from about 0.02 to about 0.25 inches.

A method for the production of nuts for roof bolts which method comprises:

• (i) casting a molten metal in the shape of a nut and
• (ii) tapping a thread through the cast metal in a manner such that the central axis of the tapped hole is offset from the central axis of the nut by from 0.02 to 0.25 inches.

A system for roof bolting, said system comprising a means for rotating a roof bolt said means including a chuck for holding the end of the roof bolt, said bolt comprising a shaft having a central axis, and wherein the chuck is adapted to rotate the bolt by means of a nut which nut is releasably locked in screw threaded engagement with the bolt so that the shaft of the bolt rotates about an axis which is offset with respect to the central axis of the shaft whereby the shaft is caused to describe a circle of diameter greater than its own diameter, the amount of said offset being from about 0.02 to about 0.25 inches.

A method for the installation of a roof bolt in a mine, said bolt comprising a shaft with a longitudinal axis, which method comprises inserting the roof bolt into a drilled hole and employing a chuck to rotate the bolt, said chuck being adapted to rotate the bolt by means of a nut in screw threaded engagement with the bolt so that the shaft of the bolt rotates about an axis which is offset with respect to the longitudinal axis of the shaft and thereby describes a circle of diameter greater than its own diameter, the amount of said offset being from about 0.02 inches to about 0.25 inches.