| 摘要 |
PROBLEM TO BE SOLVED: To efficiently construct a pipeline without making work interrupted by having a driving section of an expansion/contraction drilling bit caught in sediment, crushed powder, etc. , by preventing the driving section from being caught in them. SOLUTION: This drilling machine comprises a drilling unit 2 which is provided in a buried pipe 25 and composed of a leading body 3 and a holding body 15, and a propelling device which imparts a propelling force to the drilling unit 2. The leading body 3 comprises: a rotary table 5 which is rotatably provided at a propelling-direction leading end; a driving means 6 for rotatively driving the rotary table 5; at least one fixed drilling bit 10 which is provided on the rotary table 5 so as to be rotatable integrally with the rotary table 5; the at least one expansion/contraction drilling bit 11 which is provided on the rotary table 5 so as to be rotatable integrally with the rotary table 5 and expandable/contractible in the radial direction of the rotary table 5; and an expansion/contraction means 12 for expanding/contracting the expansion/contraction drilling bit 11. The expansion/contraction drilling bit 11 is provided at the expansion/contraction-direction leading end of the expansion/contraction means 12. COPYRIGHT: (C)2009,JPO&INPIT
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