Design And Simulation Experiment Research Of Passive Compliant Joint For Shaft Hole Assembly Operation

In recent years,with the rapid development of industrial robot technology and the urgent need for traditional manufacturing to transform and upgrade to intelligent manufacturing,industrial robots have become an irreplaceable important equipment and means in China’s manufacturing industry.Due to the large stiffness of the robot itself,when performing precision assembly operations,small pose deviations will also produce a large contact force,resulting in assembly failure,and may even damage the assembly workpiece and the entire assembly system.Aiming at this problem in the assembly operation,this paper designs a new type of passive compliant joint with four degrees of freedom for the shaft hole assembly operation.The joint can effectively compensate the small pose deviation between the shaft holes and successfully complete the shaft hole assembly operation.The main work is as follows:(1)The advantages and disadvantages of active compliant assembly technology and passive compliant assembly technology are analyzed,and a new type of passive compliant joint with four degrees of freedom is designed.According to the experimental environment and actual requirements of the shaft hole assembly operation,the design requirements and technical indicators of the passive compliant joint are determined.The overall design scheme of the passive compliant joint is proposed,and its working principle is analyzed.The mechanical structure design of the horizontal moving pair and the ball pair is carried out.The compression spring of the core component in the passive compliant joint is selected and calculated,and the main parameters such as the middle diameter,steel wire diameter and spring stiffness of the compression spring are obtained.The three-dimensional virtual assembly of the passive compliant joint is completed by Solidworks modeling software.The range of the X and Y moving pairs in the passive compliant joint is±6mm,and the angle range of the ball pair rotating around the X and Y axes is±11°.(2)The position deviation,attitude deviation and pose deviation of the four stages of the peg-in-hole assembly are analyzed The dynamic analysis of the peg-in-hole assembly operation under different deviation states is carried out by using ADAMS simulation software.The displacement variation curves of the X and Y moving pairs in the passive compliant joint and the angle variation curves of the ball pair rotating around the X and Y axes are obtained.The motion attitude of the passive compliant joint when compensating different deviations is analyzed.It is verified that the passive compliant joint can effectively compensate the peg-inhole position deviation of ±1mm on the X and Y axes and the angle deviation of±1° around the X and Y axes in its working space.It meets the requirements of pose compensation in technical indicators.At the same time,through ADAMS simulation software,the change curve of contact force in X,Y and Z directions of shaft hole assembly operation is obtained,which provides boundary conditions for finite element simulation analysis of passive compliant joints and key components.(3)Using ANSYS simulation software,the finite element simulation analysis of the passive compliant joint under the maximum contact force of the shaft hole assembly operation was carried out.The total deformation cloud map,equivalent strain cloud map and equivalent stress cloud map of the passive compliant joint under the force condition were obtained.The strength and stiffness of the key components such as the bearing inner ring,the X-direction swallow tail slider and the Y-direction swallow tail slider in the passive compliant joint were checked.The cloud diagram results show that the stress of the key components in the passive compliant joint is less than the yield strength of the material when the contact force of the shaft hole assembly operation is the largest,which meets the actual work requirements and verifies the rationality of the passive compliant joint design.At the same time,aiming at the possible resonance problem of the passive compliant joint in the assembly operation,the modal analysis of the passive compliant joint is carried out,and the vibration mode and natural frequency of the first 6 orders are obtained.The deformation of the passive compliant joint under each order natural frequency is analyzed,which provides a basis for the shaft hole assembly operation to avoid the resonance frequency and ensures the safety and stability of the joint work.(4)The passive compliant joint prototype was manufactured and debugged,and the prototype was installed on the vertical machining center.The shaft hole assembly experiment platform was built,and the assembly operation experiments of circular shaft holes and square shaft holes under different initial deviation conditions were carried out.The experimental results show that the passive compliant joint prototype can effectively compensate the±1mm position deviation of the shaft hole on the X and Y axes and the±1°angle deviation around the X and Y axes,which verifies the correctness of the passive compliant joint prototype design and the feasibility of the assembly operation.