| 摘要 |
PROBLEM TO BE SOLVED: To provide an excavating head which is free from an influence of excavation chips, dispenses with a complicated structure of a hydraulic mechanism etc. , positively expands/contracts diameter expandable bits to a predetermined value, and protects the diameter expandable bits, a rotating shaft, and a rotary body from being damaged during excavation. SOLUTION: The excavating head is mounted on a front end of the rotary body 1 which is rotated about an axis O during excavation, and formed of excavation bits 4 and the diameter expandable bits 6. The excavation bits 4 are arranged on an external peripheral side of the front end of the rotary body 1. The diameter expandable bits 6 are located at an almost equal location to that of the excavation bits 4 in an axial O direction, and between the excavation bits 4 circumferentially adjacent to each other in a circumferential direction about the axis O. The diameter expandable bits 6 are each rotatable about a rotation axis C that is spaced away from the axis O toward an outer periphery so as to expand/contract an external diameter thereof from the axis O. COPYRIGHT: (C)2007,JPO&INPIT
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