PURPOSE: To eliminate the need of mortar filling to the back so as to reduce work by rotating a projected part provided in the center of a roller bit at the forward end of an arm, taking a drilled hole of a PS steel wire as a guide, and couterboring a bearing plate contact surface.
CONSTITUTION: A roller bit 1 having a projected part 1 in the center thereof is removably installed on the forward end of arm 6 of a power shovel 4. Three truncated cone-like bits 2 where chips 3 are uniformly fitted on the whole surface of the surface are installed in the periphery of the projected part 1 in such a manner as to form a surface right-angled to the projected part 1. The projected part 1 is inserted in a bore hole for a PS steel wire, which is previously bored in the rock, a roller bit 5 is pressed to the rock by the arm 6, and the shaft and bits 2 are rotated, taking the bore hole as a guide to counterbore a surface to which a bearing plate is pressed, thereby correcting the irregularities of the rock.
HIGUCHI YOSHIHIRO
AKOSHIMA TAKAO
FUJIMOTO KAZUYOSHI
HASHIMOTO TOKUICHI
