| 摘要 |
PROBLEM TO BE SOLVED: To provide a multiple bit having a simple structure and capable of reducing manufacturing cost, coping with mass production, and preventing an earth removing device from being clogged with broken pieces when an outer bit is worn and broken. SOLUTION: This multiple bit 8 to be mounted on a cutter head 4 of a tunnel excavator 1 to cut a working face K is provided with an inner bit 10 to be attached to the cutter head 4, the outer bit 11 formed to cover a cutting chip 10b of the inner bit 10, and a mounting means 12 for mounting the outer bit 11 on the inner bit 10. The outer bit 11 has a front cover part 11c arranged in front of cutting direction A, a rear cover part 11d arranged above the direction B of working face, and a connection part 11e for connecting them. The mounting means 12 has a front side mounting means 12a for attaching the front cover part 11c to a front part 10c in the cutting direction of the inner bit 10 and a rear side mounting means 12b for attaching the rear cover part 11d to a working face opposing part 10d of the inner bit 10. COPYRIGHT: (C)2010,JPO&INPIT |
