| 摘要 |
PROBLEM TO BE SOLVED: To cut with high precision without causing eccentricity of a core of a cutting device in a curve section of a pipe passage and take out the cutting device smoothly without cutting an extra part when retracting the cutting device. SOLUTION: The cutting device is inserted into the pipe passage communicating a manhole with a manhole. One end of a wire is fixed in front of the cutting device, the other end of the wire is positioned in the manhole in the front, and the wire is pulled in to enlarge diameter of the pipe passage. Two half split spherical body guide rollers are attached to the wire in front of the cutting device, diameter of a bit part is enlarged when cutting load is applied, and diameter of the bit part is contracted when no load is applied to the cutting device. COPYRIGHT: (C)2005,JPO&NCIPI
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