Sliding expanded bit body for reverse circulation drill

摘要

The sliding expansion bit structure for RCD according to the present invention is a support plate having a bit rotation groove so that a plurality of bits are rotatably installed on the bottom surface of the plurality of bits and a plurality of side drilling bits installed at the edges of the plurality of bits are rotatably installed. And, a plurality of edge saddles hinged by a hinge shaft so as to be rotatably fixed to the bit rotation groove of the base plate, and fixed to the hinged edge saddle and rotatably fixed to the outer diameter of the casing steel pipe during excavation The side drilling bits installed on the edge of the base plate, including the installed bits, operate to be hinged, so that when inserted into the casing steel pipe, the side drilling bits are arranged in the inner diameter of the base plate, and when excavating in the ground, the side drilling bits rotate. Since it is possible to excavate up to the outer diameter of the casing steel pipe, it is possible to excavate with the same diameter as the outer diameter of the casing steel pipe even in a solid rock mass, so that the design bearing capacity can be exhibited, and the support of the entire foundation can be improved.