| 摘要 |
PROBLEM TO BE SOLVED: To prevent the sticking of a core bit occurring when a crescent-shaped slice formed by the biting of tips into a reinforcing bar comes off from concrete and is held between a core bit inner peripheral surface and a concrete core, during the drilling operation of a concrete structure with the core bit.SOLUTION: In a core bit 11 having a cylindrical body 12 to one end of which tips 16 made of diamond abrasive grains are fixed, the body 12 comprises: an outer tube 13; and an inner tube 14 coaxially disposed in the outer tube 13. A gap 15 having a fixed width is formed between the outer tube 13 and the inner tube 14 by using a flat groove 13b provided at the outer tube 13. Both tubes 13, 14 are made of steel, and the inner tube 14 is flexible. When a slice 4a of a reinforcing bar is bitten, the inner tube 14 bends and projects toward the outer tube.SELECTED DRAWING: Figure 4 |
