| 摘要 |
PROBLEM TO BE SOLVED: To provide excavating bits and casing cutters suitable for excavating the obstruction ground including reinforcements. SOLUTION: An excavating head part 2a of an excavating bit body 1 for presenting an almost rectangular solid block is provided with an excavating blade member 3, and a guide member 4 preceding to this excavating member 3 in an excavating directional reference. The guide member 4 is composed of guide pieces 6a and 6b, and restrains spring back of the reinforcements by an inclined guide surface 7, and finely cuts the reinforcements by a bar- shaped tip 5 of the excavating blade member 3. These excavating bits 1, 10 and 11 are installed in holders 22 and 34 existing on an annular end surface of cylindrical casing bodies 21, 31 and 41 to constitute the casing cutters 20, 30 and 40.
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