Roof Bolts For Use In Mines

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.

Roof bolts for use in mines. A roof bolt comprises a shaft for insertion in a hole drilled in a mine roof and a head whereby the bolt may be rotated the head being offset with respect to the longitudinal axis of the shaft so that when the bolt is rotated by means of its head the shaft is caused to describe a circle of greater diameter than its own diameter and where the offset is at least 0 08 inch and not more than 0 25 inch. The invention comprises a roof bolt and nut in screw threaded engagement said bolt comprising a shaft for insertion in a hole drilled in a mine roof and a threaded portion engaged by the nut whereby the bolt may be rotated. Jennmar is the largest manufacturer of roof control products in the u s however we don t stop there. Secondary function of roof bolts in weaker ground.

A roof bolt comprises a shaft for insertion in a hole drilled in a mine roof and a head whereby the bolt may be rotated the head being offset with respect to the longitudinal axis of the shaft so that when the bolt is rotated by means of its head the shaft is caused to describe a circle of greater diameter than its own diameter and where the offset is at least 08 inch and not more than 0 25. We can supply the construction mining or tunneling industry with much more. Dsi has one of the strongest nuts on the market. Roof bolts in helping to create a stable rock structure are the first line of defence to protect mineworkers from fall of ground related hazards which highlights the importance of correct roof.

In many mines a stronger unit that is largely self supporting overlies a weak immediate roof layer figure 1b. Experience has shown that roof bolts are extremely efficient in the suspension mode 6 7 8 though. In low seam mines the flexibility of the cable bolts allows greater length supports to be installed near the advancing face without the use of couplers. In these circumstances roof bolts act to suspend the weaker layer.

The composite bolt is particularly interesting not only because of its high tensile strength which is double or triple the strength of the steel but it is also non sparking oler said. Several longwall mines are using the tenax tencate polymer mesh roof support system. In the design and construction of mining roof bolts support support forms and parameters are selected based on experience or engineering analogy so there are some problems such as difficult roadway maintenance low coal production rate and tight mining replacement.