Study on dynamics of multistage gears in shearer cutting section

The research on gear dynamics of shearer cutting part started late at home and abroad, and the main achievements were obtained in recent 20 years. Shearer cutting part can be divided into transmission system and rocker box. Transmission system is composed of fixed shaft gear, bearing, gear shaft and planetary gear system, which is used to transmit motion and power. Transmission system can also include cutting motor and cutting drum related to gear transmission, and its specific connotation changes according to research needs.

Dolipski et al. Established the dynamic model of ksw-500 shearer cutting part drive system with lumped parameter method, and analyzed the influence of shearer traction speed and coal rock hardness on the dynamic load of drive system. The dynamic model of cutting part transmission system established by Jiang et al. Considers the influence of tooth crack on meshing stiffness. It is found that the chaotic characteristics of transmission system increase with the increase of crack degree. It is pointed out that the maximum Lyapunov exponent can be used to detect the crack degree of gear. Huang Jing et al. Considered the physical characteristics of planetary gear, fixed shaft gear, gear shaft and bearing, established the dynamic model of the transmission system of the cutting part of MG300 / 700-WD shearer, simulated the dynamic tooth root bending stress and dynamic tooth surface contact stress of the gear in the process of coal cutting, and analyzed the influence of the structural parameters of the transmission system on the reliability of the system. Because the high-speed gear is the fault prone area of the cutting part transmission system, Qian Peiyun established a 9-DOF dynamic model of the high-speed gear pair, and studied the impact load and root crack damage on the dynamic characteristics of the high-speed gear. The above research only models the transmission system of the cutting part without considering the coupling effect of the rocker box and the cutting motor.

Some scholars consider the electrical characteristics of the cutting motor, integrate the equivalent circuit model of the asynchronous motor and the lumped parameter model of the gear drive, and study the electromechanical coupling characteristics of the cutting part drive system. Liu et al. Analyzed the current characteristics of the cutting motor under the impact load of the drum, indicating that the motor current can be used to monitor the load state of the shearer drum. Yi et al. Analyzed the influence of the electromagnetic effect of the motor on the inherent characteristics of the gear drive, identified the resonant speed and dangerous components of the electromechanical coupling system by using the Campbell diagram and modal energy method, and analyzed the influence law of the gear torsional vibration on the motor current under normal speed and resonant speed. Yi Yuanyuan et al. Analyzed the electromechanical dynamic characteristics of the cutting unit drive system in the transient process of starting and motor stalling, which showed that there was a strong coupling between the motor and the gear drive in these processes, which led to the phenomenon of gear off, backlash and so on. Ge et al. Studied the suppression effect of motor active control on dynamic load of cutting part drive system under impact load, and showed that the impact energy of drive system can be effectively reduced by active disturbance rejection torque compensation control with speed difference between two ends of cutting motor elastic torque shaft as feedback signal. Liu Yonggang, Ge Shuai and Yan Zhongliang, based on the electromechanical coupling model of the transmission system of the cutting unit, studied the comprehensive influence of the traction cutting combined speed regulation on the gear dynamic load, productivity, lump coal rate and cutting specific energy consumption of the shearer. Aiming at the transmission system of cutting unit driven by multiple motors at the same time, some scholars have established corresponding electromechanical coupling models, and studied the synchronization characteristics of multiple motors from the perspectives of motor synchronization error, two motor synchronization modes (speed and torque), some motor faults and motor control methods. The above research focuses on the analysis of the coupling characteristics of “mechanical” and “electrical” of the transmission system of the cutting part, which simplifies the modeling of the mechanical part to varying degrees. For example, the coupling effect of the rocker box and the transmission system is not considered, which can not fully and accurately reflect the dynamic characteristics of the cutting part of the shearer when cutting coal.

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