| With the aspheric components are widely used in the diversity of industries,the demand for the surface quality is becoming higher and higher.Modern polishing technology is widely used in ultra-precision manufacturing as a processing method.However,there are still some problems in the polishing technology.It is very difficult to improve the polishing efficiency and surface quality at the same time.During the polishing process,it is difficult to adapt the polishing tool with the surface and control the material removal rate accurately.In view of the limitation of above weakness,this paper explores a new polishing method based on the negative compressibility.The theoretical model is constructed based on the cell of the frame structure.The drive structure of negative compressibility is designed,and the mechanism of the negative compressibility in the polishing technology is studied.Meanwhile,the experiment on the polishing machine is carried out.The specific work is as follows:1.Based on the polishing idea of negative compressibility,the principle of polishing is proposed and a set of device driven by piezoelectric actuator is designed to verify the effect of negative compressibility on polishing.The driving device is mainly composed of a piezoelectric driving module,a flexible hinge unit module,a pre-tighten module,etc.The method of ANSYS is adopted to simulate and optimize the set of device.In addition to that,the static and dynamic performance is tested during the off-line process.As a result,the stiffness,stroke,natural frequency and motion resolution are to meet design requirements of device structure.On the basis,the polishing experiment on the K9 glass is carried out.Meanwhile,the surface quality improved on the aspects of arithmetical mean deviation of the profile and maximum height of the profile.The arithmetical mean deviation of the profile improved from 18 nm to 6nm.The maximum height of the profile improved from 177 nm to 68 nm.Finally,the feasibility of the negative compressibility is further verified.2.The theoretical expression of the negative compressibility is deduced under the two-dimensional cell wine rack.The realization condition of linear negative compressibility is explored under ideal hinge mechanism.Extend to 3D structure,the configuration cell of hexahedron and octahedron are designed.What's more,the comprehensive mechanism including hinging,stretching and bending mechanism are also researched in which the hinge and bending mechanism benefit the expression of the negative compressibility and the stretching mechanism has certain suppression effect on the negative compressibility.Based on the hexahedron cell,wine rack configuration is printed through the ANSYS simulation and experiment of negative compressibility model of negative compression test,providing a theoretical basis for the design of the polishing mechanism of negative compressibility.3.The structure which has the feature of negative compressibility is designed based on the frame of wine rack.The principle of the movement mechanism is verified by ANSYS finite element method and negative compressibility test using the laser displacement sensor off-line.As a result,the displacement value of the whole structure is 4.5?m,which meet the need of the polishing process.4.The polishing experiments are carried out on the platform of five-axis polishing machine.Single factor analysis is used to select the optimum parameters of the experiments,which analyze the effects of different process parameters on the polishing effect.Then,the flat K9 glass is polished on the optimum parameters with or without negative compressibility structure,according to the general polishing path.The surface quality is detected by Zygo microscope.Finally,the results show that the method can improve the aspects of arithmetical mean deviation of the profile and maximum height of the profile. |
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