| 摘要 |
<p>PURPOSE:To speed up detection and to detect even a working face breakage state at an optional position in a circumferential direction by detecting the working face, breakage state from the angle of rotation of a cutter face and a measured voltage detected by a voltage measuring electrode. CONSTITUTION:Four electrodes 23a and 23b, and 24a and 24b are arranged on the side 21 of a skin plate at electrode intervals a1, and four electrodes 25a and 25b, and 26a and 26b are arranged at electrode intervals a2 which are wider than the intervals a1. On the front surface side of a cutter face side 22, four electrodes 27a and 27b, and 28a and 28b are arranged at electrode intervals a3 and four electrodes 29a and 29b, and 30a and 30b are arranged at intervals a4 respectively. Two outside electrodes of each group correspond to electric feeding electrodes and two inside electrodes of the group correspond to voltage measuring electrodes. Then the electric double layer consisting of drilling mud and earth is fed with electricity from the feeding electrodes and in which direction and how deep and wide the working face breakage is can be detected from the current angle of rotation of the cutter face and the measured voltage detected by the voltage measuring electrodes.</p> |
