Study on magnetic field simulation and shielding design of shearer drum height measurement sensor working environment

In order to realize the measurement of the height of the shearer drum in the complex electromagnetic environment of the fully mechanized mining face in the coal mine and ensure the reliability of the sensor under the working conditions,on the basis of analyzing the structure and working principle of the rocker arm of the drum shearer,the shearer drum height sensor was designed by using TLE5012B magnetic sensitive angle sensor element. The sensor obtains the swing angle of the rocker arm through the rocker-rotating device installed at the rocker pin shaft,and calculates the height of shearer drum from the angle calculation. According to the existing coal mine underground working conditions,equipment distribution and sensor installation position,the main magnetic field interference sources of drum height sensor in the underground working environment were analyzed and determined to be cutting motor,crushing motor,traction motor of shearer,power supply of the shearer and roadway laying cables. Using Solidworks 3D modeling software and taking Eickhoff’s SL1000 shearer as a reference,the related interference source models such as cables,motors,shearer rocker arms and surrounding parts were established. Based on COMSOL Multiphysics simulation software,the magnetic field distribution of each interference source model was solved,and the magnetic field environment of shearer drum height sensor working position was quantitatively analyzed. The simulation results show that the magnetic induction intensity of the cutting motor and the roadway laying cable is relatively large,which is the main source of electromagnetic interference affecting the work of the sensor. The magnetic induction intensity of shearer rocker arm and its surrounding parts and the sensor installation parts is 1-4 T,which is beyond the normal operating range of 30-50 mT of TLE5012B. In order to reduce the influence of electromagnetic interference on the sensor,based on the principle of low-frequency magnetic shielding and sensor structure,a magnetic shielding device was designed with silicon steel sheet as shielding material. The device can effectively shield 99% of the magnetic field interference,and the magnetic induction intensity around the sensor after shielding is 10-45 mT.