CORE DRILL

摘要

The outer peripheral surface of a core main body (14) is formed with a plurality of chip discharge grooves (16, 26, 36, 46a, 46b) extending vertically in parallel with the rotary axis of the core main body (14) from the lower to upper end of the cylindrical core body (14) provided with a drilling cutter (15) at the lower edge. Further, the cross-sectional area of the chip discharging groove (16) is gradually increased from the lower to upper end of the core main body (14). Further, the outer peripheral surface of the core main body (14) between the chip discharging grooves is formed with a number of projections (52, 62, 70, 72).