Electromechanical Coupling Dynamic Characteristic And Optimization Of New Shearer Cutting Short-range Transmission System

The drum shearer is one of the main equipment for the comprehensive mechanized coal mining equipment,which is mainly composed of three parts: cutting part,haulage unit and intermediate control box.The cutting part is responsible for the function of cutting coal and coal loading,is one of the mian operating mechanisms of the drum sheaer.The cutting part is consisting of cutting drive motor,gear transmission,cutting drum and other components.The ranging arm housing is both a supporting part and a positioning part of the transmission gear,and is also the supporting part when the drum around the center arc movement take-off and landing.The ranging arm housing is not only subjected to the gravity of the cutting part and the three-axis force from the end of drum when shearer mining operation,but also subjected to the overload and strong impact load caused by hard parcel or dirt band.The ranging arm housing is in a state of complex tension-pressure-bending stress and impact stress,ease to deform.In addition,the transmission chain of the cutting part is long with a large number of transmission components,resulting in the ranging arm housing becomes a hollow cantilever beam.Then,the structural strength of the housing is reduced and the deformation of the housing is exacerbated.For the gear transmission system installed in the housing,the deformation of the housing will result in the deterioration of gear meshing condition,thus reducing the reliability of the transmission system.Therefore,to improve the working reliability of shearer,the first step is to improve the operational reliability of the cutting transmission system.In view of the widely used drum shearer whose cutting drum don't have the speed regulation function,the reduction of the drum load and the internal dynamic loads of the cutting transmission system can only be achieved by reducing the haulage speed when the drum encounters the hard coal or dirt band,thereby protecting the cutting transmission system and the cutting driving motor.However,as the haulage speed decreases,the coal mining productivity also decreases.The rotational speed of the cutting drum can be adjusted by controlling the rotational speed of the driving motor with the aim of improving the adaptability of the drum shearer and obtaining the best coal mining productivity and lump coal rate in different coal seam conditions,which establish the theoretical base to the development and designing of the intelligentized and unmanned shearer.The research work of this paper is as follows:(1)Aimed at the problems of the transmission chain of the cutting part is long with a large number of transmission components,the deformation of the housing caused by the heavy load and strong impact load worsens the gear meshing condition,the low reliability and low transmission efficiency of cutting gear transmission system and a new shearer cutting short-range transmission system is proposed.In this system,the drum speed can be adjusted by controlling the driving motor.(2)Aimed at the structural features of multi-power sources,multiple mehing pairs,multi-stage transmission for the new shearer cutting short-range transmission system,and considering the coupling relationship between the motion and force of each component.An electromechanical coupling dynamic model of the cutting short-range transmission system is established,including driving motor,control system of motor and gear transmission system.This laid the model foundation for the electromechanical coupling dynamic characteristic analysis.(3)Considering the coupling relationship between the parameter of driving source and the movement-force of each component,the influence of the motor inherent characteristic on the vibration response and dynamic meshing force and the influence of driving torque out of sync,rotational speed of motor on the vibration and load sharing characteristics of the gear transmission system are investigated.Compared with the dynamic characteristics of the motor without considering the gear transmission system,the influence of gear transmission system on motor torque,speed and stator current both in time-domain and frequency-domain and the influence of gear meshing stiffness fluctuation,transmission error on synchronization characteristics are studied,respectively.(4)Choose the appropriate speed regulation mode(increase the rotational speed of cutting drum,or reduce the haulage speed,or drum-haulage joint speed regulation),the electromechanical coupling dynamic characteristics of the cutting short-range transmission system of variable speed cutting shearer under different loads(impact load and step load)and different kinds of speed regulation schemes(drum-haulage joint speed regulation and drum-haulage sequence speed regulation)are investigated to improve the adaptability of shearer to different cutting situations and to obtain the best coal mining productivity,lump coal rate in different coal seams.(5)An optimization method is proposed that can be used to improve the electromechanical coupling performance of shearer's cutting short-range transmission system.The vibration displacement,dynamic meshing force and system synchronization error are selected as the evaluation index of the electromechanical coupling performance of the system.Considering the change of the input parameters such as meshing parameters,connection parameters,supporting parameters and external load,a surrogate model is established that can be used to analysis the electromechanical couping performance of the system.The sensitive parameters are determined by using the Sobol' global sensitivity analysis method and the influence of the sensitive parameters on the performance evaluation indices were investigated.The performance evaluation indices are selected as the optimization objective and the sensitive parameters are selected as the optimization variables.Then,the multi-objective optimization is carried out to obtain the optimal design parameter of the system in the case of different trade-off condition for multi-dimensional optimization objective.(6)The test bed of the cutting short-range driving system of shearer is designed and constructed,and the corresponding data acquisition and control system is also builded based on dSPACE.The experimental research on the electromechanical coupling dynamic characteristics is carried out under the impact load,step load,different load change rate,different drum acceleleration and different speed regulation schemes.The model and the theory research results obtained in this paper are verified finally.