| 摘要 |
PURPOSE:To exactly detect cutting of sheet piles by a method in which the diameter of a rotary cutter is detected during cutting, the center position of the cutter is also detected, and on the basis of both data, the cutting of the sheet pile is detected. CONSTITUTION:A cutter 2 is fixed to the inner wall of the main tube 1a, and an abrasive cutter 6 is turned and allowed to come near the inner wall on the coupler tube 1b side of the tube 1a. The actual diameter of the cutter 6 is detected by a sensor 40 and the center position of the cutter 6 is detected by a sensor 42. The ending of cutting the tube 1b is detected by geometrical calculation from the detected data and the diameter of the tube 1a. The lowering of operating efficiency due to incomplete cutting of the coupler tube can thus be prevented.
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