Research On Vibration Failure Mechanism Of Long Screw Of Shearer

The working environment of the drum shearer is bad.When the drum cuts coal and rock,the drum itself will be subjected to the coal and rock reaction,and the load has the characteristics of randomness.The complex stress conditions cause the Shearer to produce violent vibration.The long screw(also known as the hydraulic pull rod)is an important fastening component of the drum shearer body.By cooperating with the high-strength hydraulic nut,the left and right traction boxes and the middle electric control box of the shearer are connected as a whole.The shearer is subjected to impact load in the process of cutting coal and rock,which causes the vibration of the Shearer to be transmitted to the long screw through the left and right traction parts.When the external excitation frequency is close to or consistent with the natural frequency of the long screw,the long screw will produce resonance.After the resonance,the transverse amplitude of the long screw will continue to increase,generating additional alternating stress,causing fatigue fracture of the long screw,resulting in the separation of the three sections of the shearer body,It seriously hinders the cutting and coal loading of the drum shearer.Therefore,it is of great significance to improve the reliability and service life of the shearer by analyzing the causes of the fracture failure of the long screw and making corresponding improvements to improve the anti vibration fatigue performance of the long screw.This paper takes MG450/1050-WD shearer and its supporting long screw as the research object.Through the theoretical analysis,simulation analysis and experimental verification of the vibration characteristics of the shearer and its supporting long screw,the causes of the fracture failure of the long screw are obtained,and the corresponding vibration reduction measures are put forward,which effectively improves the anti vibration performance and service life of the long screw.(1)Based on the analysis of the research status of shearer and long screw at home and abroad,the research subject on the transverse vibration characteristics of long screw is put forward;Based on the calculation of the three-dimensional force on the shearer drum and the mechanical analysis of the whole machine model,the vibration response model of the shearer is established based on the vibration mechanics theory;The threedimensional model of the shearer is simplified and modal analysis is made.Combined with the design parameters of the shearer,it is concluded that the vibration frequency range of the long screw resonance caused by the shearer is 0～200Hz;(2)The vibration mechanical model of the long screw is established,and the factors affecting the natural frequency of the long screw are obtained;Through mechanical analysis of the long screw,the change of the total tension of the long screw in the working process of the shearer is obtained;Through modal analysis,harmonic response analysis and vibration fatigue simulation analysis,the resonant frequency and corresponding fatigue life of the long screw are obtained;According to the analysis results,the vibration reduction measures of the long screw are put forward,and the modal analysis,harmonic response analysis and vibration fatigue simulation analysis of the improved long screw assembly are carried out to evaluate the effectiveness of the vibration reduction measures;(3)The experimental platform was built and the vibration characteristic experiment of the long screw was carried out to explore the influencing factors of the natural frequency of the long screw.The correctness of the vibration mechanical analysis and modal simulation analysis of the long screw was verified.At the same time,the vibration reduction measures of the long screw effectively improved the anti vibration performance of the long screw.