The use of support plates to reinforce or stabilize mine roofs, in order to prevent roof falls is well known and generally use support plates that are held flush to the mine roof by bolts secured in bore holes formed in the rock strata of the roof.
Some bolts are anchored in the bore holes by the use of a mechanical means such as anchors that expand and are secured to the wall of the bore hole, while others are secured in the bore holes by a quick setting resin. Other bolts have been secured by the use of a combination of mechanical and resin means.
Examples of a combined mechanical-resin anchoring system for mine roof bolts are illustrated in U.S. Pat. No. 4,162,133 and U.S. Pat. No. 4,299,519, where an expansion anchor is provided and the combination rotated together in one direction in a bore hole to break a resin package and the rotation then reversed to anchor the bolt by expansion of an expandable anchor.
In U.S. Pat. No. 4,313,697, which issued to my father, Richard C. Rozanc, and which is incorporated by reference herein, a mine roof support plate bolt is described which is formed from a concrete reinforcing rod, or rebar, and has a helical channel at one end thereof. The helical channel is formed in the rebar in a direction opposite the rotation of the bolt during fixation of the bolt in a bore hole and a resin package inserted into the bore hole preceding the bolt is shredded by teeth in the end of the bolt, with the resin released from the resin package pumped towards the end of the bore hole so as to retain the resin at the end portion of the bolt in the bore hole and provide a more secure anchoring thereof.
Because the placement of mine roof bolts in bore holes is a labor intensive procedure, however, development has been desired of a bolt that is readily and quickly secured in a bore hole in a mine roof which will enable time savings while retaining the safety of a securely anchored bolt and mine roof support plate. While the mine roof support plate bolt described in U.S. Pat. No. 4,313,697 is suited for secure anchoring of the bolt in a bore hole, even quicker securement of the bolt would be beneficial in order to speed up the securement of support plate to a mine roof and stabilizing thereof, while maintaining secure engagement of the bolt in a bore hole.
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