| 摘要 |
PROBLEM TO BE SOLVED: To provide a cutting device for a buried pipe comprising a structure allowing to prevent an increase of a working time by optimizing depth of cut of a cutting edge corresponding to wall thickness by easily calculating a machining starting position for an internal cutter positioned in an existing pipe. SOLUTION: This cutting device for the existing pipe comprises a structure to cut a part of the existing pipe by a cutter so as to draw and remove the existing pipe buried in the ground. The cutter 3 is provided with a rotary dividing shaft 6 inserted from one end of the existing pipe, a cutter edge 9 driven by the rotary driving shaft 6 capable of freely expanding and contracting a diameter, a driving source 4 to drive the rotary diving shaft 6, a transmitting means 8 to convert driving force from the driving source 4 into expanding and contracting motion of the cutter edge 9, and a structure 21 to calculate an expanding and contracting amount of the cutter edge 9 from an operating amount of the transmitting means 8. The device is also provided with a structure capable of expanding the diameter according to the depth of cut corresponding to the wall thickness of the existing pipe with starting from a condition where the cutting edge of the cutter edge 9 abuts to the inner surface of the existing pipe.
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