| 摘要 |
An anchor bolt assembly for strengthening mine roofs constructed of a cylindrical anchor member having a bolt threadably received in one end and a temporary thread advancing stop carried on the stem of the bolt which releases or gives only after a predetermined torque is applied to the bolt, relative to the anchor member, to permit the bolt to be finally drawn up against the face of the mine roof after the anchor member into which it is threaded has been solidly secured with an adhesive resin material within a predrilled bore hole in the mine roof. The stop provided on the bolt stem may be of a type which shears or strips from its position on the bolt stem when the bolt is threadably advanced into the anchor member with the application of a predetermined relative torque, or the stop may be in the form of a frusto-conical wedge secured to the bolt stem and having the narrow end of the wedge projecting into a large counterbore in the end of the anchor member so that the frusto-conical face of the wedge seats against the inside opening of the counterbore to act as a stop. In this latter-mentioned stop, the counterbored end of the anchor member is provided with a plurality of annularly spaced open end slots so that upon applying the predetermined torque to the bolt relative to the anchor member, the frusto-conical wedge is further forced into the counterbore causing the slotted end of the anchor member to radially expand and engage the sides of the bore hole as an additional anchor member.
|
