The Virtual Prototype Design And Analysis Of Liner Replacement Manipulator On Ball Mill

Ball mill is the main mineral grinding equipment in mining industry,the inner liners are easy to be worn out.In practice,liner is one of the parts that will be replaced most frequently in the ball mill.The cycle is short,but it will take worker a long time to replace the liner.A concentrating mill uses the hoist crane to replace the liner for a long time.But,the way is no only inefficient but also manpower requested.In order to improve the efficiency of replacement of the liner,according to a ball mill of the concentrating mill,this paper discusses the designation of virtual prototype of the manipulator.Through theory study and simulation prove the feasibility of the model.The main research works are listed as follows:(1)Application of software SolidWorks,the three-dimensional model of Liner replacement manipulator on ball mill was built,based on the practical data which was determined,such as cylinder diameter,length,inlet diameter,the weight of the largest liner.The focus of the design is to add three degrees of freedom in the wrist of the manipulator,so that it has adjustment ability of yaw,roll and pitch.The three degrees of freedom collaborative work can replace the liner more accurate and faster,without the need for manual assistance.And,the end clamping device use the driving method of telescopic hydraulic cylinder to accurately clip the liner.Then,the method of interpolation is used to plan the working process of the manipulator,and using the Motion plug-in to simulate the working process of the manipulator,the results showed that the manipulator can complete a given working target,and verified the rationality of the structure design.(2)In order to verify the rationality of each connecting rod parameters of the manipulator,based on the analysis of the structure of the manipulator and the parameters of the connecting rod by the D-H method,the kinematical equation was established.Application of software Matlab,the kinematics simulation of the manipulator was finished based on the kinematical equation,then obtained the curve of the end of the manipulator from any point to a specific location,and the curve of the joint displacement and velocity.These verified the correctness of the kinematic equation.According to kinematic equation,this paper introduced the manipulator relevant theories of Jacobi matrix and static characteristics,then the force and torque of each joint were calculated,which maintain the balance of the manipulator when the clamping jaw is under stress.Through theoretical calculation and simulation proved that the connecting rod parameters of the manipulator are reasonable.(3)The theoretical basis of finite element modal analysis,the method of modal extraction and analysis were studied,the three-dimensional model of the manipulator was simplified without affecting the result of the analysis,then imported it into software Workbench.The first 5 order natural frequencies and vibration-mode of the manipulator were gained by modal analysis of finite element model.Through the observation of the results found that the manipulator easily cause resonance under the excitation of 40~50Hz,and easily deformed at the end of the manipulator in the case of resonance,that providing a theoretical basis for avoiding resonance in the work.(4)Based on the modal analysis,the author made transient dynamic analysis of the manipulator to determine the displacement and stress response in the maximum dynamic load at the moment of lifting the liner,mainly concentrated at the end of the manipulator and it had little effect on the other parts.And the maximum stress and displacement response were about to occur in the wrist position of the manipulator.Through observation and analysis of the results,the strength of the manipulator meets the requirement of the design.