ATTACHMENT FOR DRILLING BIT FOR USE IN TUNNEL PLANK METHOD, NATURAL GROUND DRILLING METHOD, AND DRILLING DRILL

摘要

PROBLEM TO BE SOLVED: To provide means capable of preventing catching of a drilling bit by splinters on wood and of pulling a drill out easily after drilling a natural ground or the like through wood.;SOLUTION: A cutting blade is provided on a drilling bit at a location on a back side of a bit edge and splinters formed on a fracture surface of wood due to advancement of the drilling bit is cut with the cutting blade when a natural ground and the like is drilled with the drilling bit or when the drilling bit is pulled out.;SELECTED DRAWING: Figure 2;COPYRIGHT: (C)2018,JPO&INPIT