Research and implementation of monitoring system of disc cutter rotation speed

The disc cutter is a main cutter to break rock in the Tunnel Boring Machine (TBM), but its abnormal state will increase the wear and may even cause the damages to the cutter head. But the cutter wear can only detect the limit of tool use, Therefore, real-time monitoring of the rotational speed of the disc cutter has become an urgent technical problem needed to be solved for TBM. This paper analyzes the disc cutter’s structural feature, and the periodic characteristics of disc cutter presented in the rotation process. Then, a monitoring system of disc cutter rotation speed is proposed based on the wear of the disc cutter detected by the eddy current sensor. The wear signal of disc cutters is sampled at a certain period for a long time. Through Fast Fourier Transform (FFT), the frequency character of wear signal is extracted. The rotational speeds of actual disc cutters under different installation distances and different rotational speeds are verified by similar disc cutters in the laboratory. In an engineering project, the rotational speeds of two edge disc cutter on an atmospheric cutter head with a diameter of 15 meters is monitored to verify the method. Results show that the cutter speed could be detected accurately and effectively when the wear amount is less than 20mm.