| 摘要 |
PROBLEM TO BE SOLVED: To enable a hole saw to cope with workpieces such as wall parts of a building in which metallic materials are mixed, without replacing the hole saw, and thereby to apply drilling operation to the workpieces without causing a drop in the working efficiency. SOLUTION: In a hole saw 4 made up of a cylindrical body 41 and a cutting part 44 formed on one end edge of the body 41, plural cutting tools 45 formed circumferentially at about equal intervals and relief grooves 46 for discharging chips formed between the cutting tools 45 are provided on the cutting part 44. The relief grooves 46 are each composed of short relief grooves 46a the depth of each of which is shallow, and a long relief groove 46b the depth of which is deep, and the cutting edges 45 are made of cemented carbide.
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