| The modern manufacturing industry is developing rapidly,and the machine tool has a pivotal position.Among them,the hybrid machine tool provides a new research direction for the field of mechanism science,and has been widely concerned by scholars at home and abroad.The hybrid machine tool has the advantages of high processing precision,fast response speed and large working space of the tandem machine tool,and has broad prospects in the fields of aerospace,defense and military industries.At the same time,the redundant drive can eliminate the singular configuration to a certain extent,can effectively improve the joint driving force,and improve the smoothness of the machine tool drive,so it has gradually become a development trend.In this paper,a hybrid machine tool mechanism consisting of a planar 3-DOF parallel mechanism and a spatial 3-DOF redundant parallel mechanism is used to analyze the mechanism configuration,kinematics and dynamics performance.On this basis,The structural stiffness analysis and modal analysis of the machine tool were carried out,and the rationality of the analysis was verified by simulation examples.The research shows that the redundant drive hybrid machine has the advantages of large working range,high rigidity,no singular configuration and convenient operation.It can be used to process precision integral structural parts,laying a foundation for the structural design,manufacturing and control model of subsequent machine tools.The theoretical basis.The main research contents are as follows:1.The configuration analysis of the hybrid machine tool mechanism was carried out by using the spiral theory.The principle and degree of freedom of the mechanism are analyzed by using the spiral theory.The correctness is verified by the G-K formula.Themechanism-driven input is selected based on the spiral theory,and the rationality of the drive selection is analyzed.The research shows that the redundant hybrid mechanism studied in this paper is reasonable in configuration,and the mechanism can move along the x,y,and z axes and rotate around the x,y,and z axes.2.The kinematics analysis of the hybrid machine tool mechanism is carried out by using the analytical vector method.The inverse kinematics model of the mechanism is established by analytic vector method,and the driving displacement is solved.The position inverse solution calculation and simulation verification are carried out by using MATLAB and ADAMS software.On this basis,the velocity analysis and acceleration analysis are carried out.The velocity Jacobian matrix and the acceleration Hessian matrix are derived by the influence coefficient method when the attitude of the moving platform and the position of the tool tip are known.The limit search method is used to search the working space of the hybrid machine tool,and the attitude working space of the main mechanism of the machine tool is obtained.The research shows that the kinematics of the machine tool is good,the working space is relatively large,and no singularity occurs during the processing.3.Dynamic analysis of the hybrid machine tool mechanism based on the principle of virtual work.Based on the calculation of the overall virtual energy of the machine tool mechanism,the dynamic model of the mechanism is established by using the principle of virtual work,and the simulation force calculation is carried out by MATLAB to obtain the driving force variation curve of the seven driving branches of the hybrid machine tool mechanism.Research shows that the drive rods and the drive slides are reasonably stressed,which lays a foundation for further research on the dynamic performance of the machine tool.4.The structural stiffness analysis of the machine tool mechanism was carried out using ANSYS software.Three-dimensional models of five special positions of the machine mechanism are introduced into ANSYS,meshed,and constraints and loads are applied.Solve the X,Y,Z direction and the total maximum deformation of each position of the machine tool mechanism,and calculate the minimum stiffness value in each direction.Through the analysis,the stiffness changes with the posture and the weak part of the machine tool mechanism isfound,which provides a reference for the structural design of the subsequent machine tool and the improvement of its machining accuracy.5.The modal analysis of the hybrid machine tool mechanism was carried out using ANSYS software.The finite element model is established,and the modal modes of five typical poses of the hybrid machine tool mechanism are analyzed.The first six natural frequencies and vibration modes of the five poses are solved,and the first six orders of vibration law of the machine tool mechanism are analyzed by the vibration mode cloud image.To determine the weak link of the machine tool structure,and provide reference for the dynamic analysis and structural optimization design of the machine tool. |
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