| In recent years,China’s transportation system has developed rapidly,and the full-section shield tunneling machine,referred to as the shield machine,is widely used in transportation system-related projects.The hob is the main rock breaking tool of the shield machine,and the hob is extremely prone to wear in a harsh working environment.Failure to replace the worn-out hob in time will result in a decrease in construction efficiency and may even cause damage to the hub and the cutter shaft,causing huge losses to the project.Detecting the parameters of the hob during the working process is an important problem in the construction process of the shield machine.At present,in the construction process,the experience of the construction personnel is mainly used to judge the wear state of the hob,or to open the warehouse inspection at the time of shutdown inspection.These methods are not only inefficient,but also cause safety hazards.Based on the literatures on the detection of hobs for shield machines at home and abroad,this paper proposes a method for detecting the wear and rotation speed of hobs using the non-contact non-destructive testing technology of eddy current sensors.The eddy current testing method is applied to the detection of hob wear.The force analysis of the cutter hob breaking rock is studied.The wear pattern of the hob under different stress conditions is analyzed.The knife wear detection system provides theoretical preparation.The simulation model of hob wear detection based on eddy current method was established by using COMSOL Multiphysics.The feasibility of using eddy current testing technology to detect the wear of the cutter hob was analyzed.The influence of different coil parameters on the eddy current test results was analyzed.The selection of parameters such as the size,excitation frequency,and number of turns of the detection coil was analyzed.The realization algorithm of the correlation function and the problems that can be solved by the correlation function are analyzed.On this basis,the method of detecting the rotation speed of the hob by using the correlation function is proposed,and the realization process of the hob rotation speed detection is designed.The eddy current detection system was built,and the upper computer system was developed under the Labview environment,realizing the real-time waveform display,numerical display and storage of monitoring data.The eddy current testing system was used to detect the wear,wear and speed of the cutter hob,and theexperimental results were compared with the actual wear of the hob.The experimental results show that the eddy current testing system is used to detect the wear and rotation speed of the hob with high accuracy and reliability.The detection system can accurately identify the different wear patterns of the hob.The detection system has a maximum resolution of 0.0012 mm for the detection of the hob wear,a maximum relative error of 5.6%,and a maximum relative error of 1.2% for the hob rotation speed detection. |
