Research On Structure Of Micro-displacement Worktable Based On A Novel Rhombic Amplification Mechanism

With the dramatic development of scientific technology in recent years, the research area of human being is expanded from macroscopic field to microcosmic field. Particularly in photology, bioengineering and microelectronic technology, the operation objects are becoming smaller and smaller, therefore requirements on miniaturization and precision of instruments are getting higher and higher, which leads urgent research on micromanipulation system with high positioning accuracy. Since the micro-displacement worktable plays an important role in modern advanced industrial production and scientific research area, it is attracting increasing interest and intensive study all over the world. Although the existing micro-displacement worktables can provide high precision, their travel ranges are small and application areas are limited. In order to overcome these disadvantages, a novel micro-displacement worktable is proposed in this paper, which utilizes the rhombic amplification mechanism to amplify the output displacement of the driving element.The main achievements in this thesis include the following aspects:(1) The MTp piezoelectric ceramic is adopted as the driving element in this paper. Its hysteresis and nonlinear characteristics are studied, and its hysteresis and nonlinear errors are calculated as well according to the experimental data. Meanwhile, the flexure hinge, which serves as the transmission structure, is analyzed theoretically to deduce the calculation formula of rotational stiffness. Afterwards, the finite element method is used to prove the correctness of this formula.(2) Since piezoelectric ceramic can only output small displacement, a rhombic amplification mechanism is proposed to enlarge the displacement. Its amplification factor is 12 in theory, and its parameters are optimized by static analysis of finite element method. With the selected parameters and finite element method, the maximum stress analysis and model analysis of this optimized rhombic amplification mechanism are carried out to verify its feasibility and security.(3) On the basis of driving element, rhombic amplification mechanism and guide mechanism, the general structure of the micro-displacement worktable is determined, and a micro-displacement worktable based on a novel rhombic amplification mechanism is designed. By utilizing theory of mechanics of materials, the formulas of maximum stress, stiffness and natural frequency of the dangerous section are obtained, and these values are calculated with selected parameters. The finite element method is employed to confirm the design rationality of this mechanism.(4) The micro-displacement worktable is trial-produced and the relevant experimental test is carried out, which indicates that the actual amplification factor of this rhombic amplification mechanism is 5.85, lower than theoretical value of 12. In the end, the causes of error are analyzed, and corresponding approaches to improve the performances of micro-displacement worktable are put forward.