Analysis Of Variable Stiffness Mechanism And Mechanical Characteristics Of Micro-nano Probe Supported By Suspension Wire Constraint

With the continuous development of microfabrication technology,the size of workpiece is gradually changing to miniaturization,and it is urgent to need a higher precision micro-nano measuring device to ensure the surface quality of the workpiece.The probe is an important part of the micro-nano measuring device.According to the different measuring process and objects,the probe needs to have different stiffness.However,most of the probe structures do not have variable stiffness performance.Therefore,the study of variable stiffness micro-nano measuring probe plays an important role in improving the performance of micro-nano measuring device.This paper introduces the basic requirements of micro-nano probes,and systematically expounds the common structure,measuring process and measuring principle of contact probe.Based on the above-mentioned variable stiffness requirements of the probe,a novel structure of variable stiffness micro-nano probe with suspension wire constraints is designed.The structure of variable stiffness probe consists of a compliant guiding mechanism and a suspension-restrained probe structure,using a capacitive sensor as the detection device.The stiffness theoretical model of probe displacement and capacitance variation is established.And the orthogonal test method is used to optimize the size parameters of the probe,and the stiffness,modal,harmonic response and isotropic characteristics of the XY plane are analyzed.The piezoelectric effect and the working principle of piezoelectric ceramics are systematically expounded,and the characteristics of four hinges and three common flexible guiding structures are introduced.Based on piezoelectric ceramics and compliant guiding mechanism,a new flexible guiding mechanism is designed,which can change the displacement of the free end of the suspension wire.Taking the magnification of the compliant guiding mechanism and the required stiffness of the stacked piezoelectric ceramics as indicators,the length and angle of the hinge are optimized,and the modal,stress and fatigue characteristics of the optimized compliant guiding mechanism are further analyzed.The stiffness theory model of variable stiffness probe system is established,and the modal,transient and stress characteristics of variable stiffness probe system are analyzed.Based on the variable stiffness theoretical model established above,thesimulation and theoretical errors of the probe along the Z and X directions are 5.612%and 6.763%,respectively.The results show that the established theoretical model has higher accuracy.According to the range of stiffness and frequency of the probe,it can be seen that the structure of the micro-nano probe can satisfy the requirement of variable stiffness.The research results enrich the structure of the existing probes and lay an important theoretical foundation for the variable stiffness control of this type probe.Figure [64] table [26] reference [72].