Structural Design And Mechanical Characteristic Study Of A New Type Of Parallel Flexible Restraint Probe

The three dimensional precision measurement technology is one of the key technologies in the field of mechanical engineering,which is widely used in the precision measurement and characterization field of Micro-Electromechanical Systems(MEMS)and micro components,to a large extent,It embodies the development level of a country's manufacturing industry.The probe is the key part of the precision Coordinate Measuring Machine(CMM),whose performance directly affects the overall accuracy of the CMM.Therefore,it is of great significance to develop a new type of probe for precision geometry measurement,which can improve the quality of parts processing,advance the progress of precision measurement technology and the development of advanced manufacturing industry.The parallel mechanism has the advantages of short structure,short motion chain,high motion precision and good dynamic response,by replacing the traditional motion pair with the elastic hinge,a parallel flexible mechanism can be obtained,which can eliminate the effect of mechanical friction and kinematic pair clearance on precision,and especially suitable for the restraint supporting mechanism with high precision and good dynamic response.When the parallel mechanism is located in a singular position,the mechanism is very sensitive to the external load and disturbance.Selecting Singular configuration of Stewart as the working position which is coplanar with moving platform and fixed platform,replacing rigid spherical hinge of mechanism with flexible ball hinges,fixed prismatic pairs,a new type of parallel compliant mechanism is constructed,and applying it to the constrained support mechanism of the precision probe.Grassmann line geometry and the screw theory are used to explain the degree of freedom(DOF)of the configuration of the mechanism.The stiffness matrix of the probe is constructed by using the statics of the parallel compliant support mechanism and the stiffness model of the branch bar,and the force-displacement model of the parallel compliant constraint mechanism are established.By numerical simulation and the finite element tools,the theoretical models was verified.The collaborative simulation of Solidworks and ANSYS Workbench is also used to explore the relationship between the sensitivity of the x,y,z direction and the feature size of the probe.Besides,the parameters of the elastic support mechanism of the probe are optimized by the orthogonal test method.Employing the finite element analysis software ANSYS Workbench,the modal analysis,the harmonic response analysis and the linear buckling analysis of the probe are carried out.The first six natural frequencies and mode shapes,displacement response curves of the probe and the linear buckling critical load of the probe in the x axis,the y axis and the z axis are obtained,the dynamic characteristics of the parallel compliant restraint probe are also analyzed.