Dynamic Characteristic Analysis And Experiment Research On The Gliding Plow System

The plow is the large coal mining equipment for the thin or very thin coal seam mining,the dynamic characteristics of the plow influence the reliability and the stability of the entire system directly,also is the main factor influencing the mining efficiency.Thus,by combining the theory analysis,the numerical simulation and the experiment validation,the dynamics characteristics of the plow system are studied.Firstly,the fitting equations of the cutting depth modification factor and the plow speed modification factor are generated.Aiming at the low precision of the traditional cutting load model for the bit,the bit three-direction load equation modification method is proposed by employing the cutting depth modification factor and the plow speed modification factor.Based on the mechanical characteristics testing experiment platform of the plow,the bit three-direction load experiment is performed under 5 cutting depths and 5 plow speed conditions,the bit three-direction load data are obtained.According to the experiment data,the fitting equations of the cutting depth modification factor and the plow speed modification factor are generated by applying the data fitting method and the correctness of the fitting equations are validated by the experiment.Under this experimental condition,the modification of the traditional cutting load model for the bit were realized.The data fitting equations of the cutting depth modification factor and the plow speed modification factor provide the base for the plow system dynamics characteristics research and the dynamics characteristics for the contact impact between the plow body and the sliding frame body.Secondly,the plow system dynamics characteristics are researched.The plow system dynamic continuous model is established by applying the continuous system vibration theory,the nonlinear time-varying dynamics model is set up by employing the finite element method.The plow system dynamic continuous model and the time-varying dynamics model under the stable cutting condition are solved respectively by applying the numerical analysis method,the tension data of the plow chains in the front and the rear of the plow body are obtained by the experiment,the compassion between the experiment data and the solved results shows that time-varying dynamics model is of the higher precision.Thus,based on time-varying dynamics model,the 4 startup schemes,the startup schemes from the different positions and the dynamic characteristics under the braking condition of the plow system are studied.The results show that the tension shock of the plow chains in the front and the rear of the plow body of the controllable inverse "s"curve startup is the minimum in the 4 startup schemes;the distance between the plow body and the machine head influences the tension of the plow chains in the front and the rear of the plow body,the smaller distance influences the tension obviously.Based on nonlinear time-varying dynamics model,by applying the geometric method,the position equation of the plow head and the sliding frame body is derived,the influence of the cutting depth,the oblique planning and feeding speed,the middle trough angle,and the oblique cutting and feeding position to the tension of the plow chains in the front and rear of the plow body are researched.The results show that the bigger the cutting depth and the oblique cutting and feeding speed are,the larger the tension shock of the plow chains in the front and rear of the plow body is;under the conditions that the cutting depth,the oblique cutting and feeding speed and the number of the middle trough are invariant,the influence of the middle trough angle to the tension of the plow chains in the front and rear of the plow body is small;the distance between the plow body and the machine head influences the tension fluctuation of the plow chains in the front and rear of the plow head in the oblique cutting process,the smaller the distance is,the bigger the fluctuation is.Thirdly,the contact impact dynamics characteristics of the plow body and the sliding frame body is researched.Based on the clearance mathematical model between the plow body and the sliding frame body,taking the distance from the point to the line algorithm as the testing criterion,the dynamics models considering the influence of uneven floor and bit three-direction load for the contact impact between the plow body and the sliding frame body in the transverse section and in the longitudinal section are established respectively by applying the contact impact theory.The influences of the cutting depth,the plow speed and the clearance size to the dynamics characteristics for the contact impact between the plow body and the sliding frame body are researched by applying the numerical analysis method.The results show that with the increments of the cutting depth and the plow speed,the contact impact forces mean between the plow body and the sliding frame body in the transverse section and in the longitudinal section decrease,and with the increments of the clearance sizes in the transverse section and in the longitudinal section,the contact impact forces mean between the plow body and the sliding frame body in the transverse section and in the longitudinal section increase.Finally,the experiment validation for the dynamics characteristics for the contact impact between the plow body and the sliding frame body is performed based on the plow mechanical characteristics testing experiment platform.The experiment results show that the vibration acceleration of the plow body decrease with the increments of the cutting depth and the plow speed,and it is accordance with the theoretical research.