| 摘要 |
PURPOSE:To raise the accuracy of measurement in which a sensor for the opening amount of a cutter, a sensor for the lowering amount of a bucket, and a transmitter for detected signals of these sensors are provided, the transmitter is set on a rotary base, a signal receiver is attached to a rotary joint, and an antenna of loop type is formed. CONSTITUTION:An encoder 2 is provided for a sensor 1 for the opening amount of a cutter, and the detected signals S1 are sent out. Also, the detected signals S2 from a sensor 10 for the lowering amount of bucket below a rotary base 23 are sent out. The signals S1 and S2 are sent out from a loop antenna for transmission by a transmitter 20 attached to the base 23 and received by the antenna 31 of a receiver 30 fixed to a rotary joint. A cutter 102 contracted into a well 200 is turned by a kelly bar 112, during which period the bucket 101 is lowered to excavate a conical bottom while opening the cutter 102 in order to form an expanded bottom 201. The operability and operating efficiency of the work can thus be enhanced. |
