| 摘要 |
PROBLEM TO BE SOLVED: To reduce cost by facilitating production of a core drill efficiently discharging chips generated by a drilling blade to an upper side and improve drilling efficiency by reducing frictional resistance with a concrete hole. SOLUTION: A plurality of lines of a chip discharge grooves 16, 26, 36, 46a and 46b of a vertical direction in parallel with a rotary shaft of a cylindrical core main body 14 are formed in a circumference direction on an outer peripheral surface of the core main body 14 from a lower end part to an upper end part of the core main body 14 provided with the drilling blade 15 at a lower end edge. Cross-sectional area of the chip discharge groove 16 is gradually increased from a lower end to an upper end of the core main body 14. A large number of projections 52, 62, 70 and 72 are provided on the outer peripheral surface of the core main body 14 among the chip discharge grooves 16, 26, 36, 46a and 46b. COPYRIGHT: (C)2004,JPO&NCIPI
|
