Research On The Nanogrinding Technology Of Micro Spherical And Aspherical Parts

Micro spherical and aspherical components have been more and more widely used in aerospace, optical system and digital products with the rapid development of science and technology. These key components often choose super-brittle-hard materials that are difficult to machine but have the properties of high hardness, anti-abrasion and well chemical stability as their body, attributing to their extreme requirements of the surface quality especially for molds that are used for glass modeling. The traditional processing method enhanced machining accuracy by combining grinding together with polishing, but which was low in efficiency, high in cost and difficult to guarantee the dimensional accuracy. The rapidly advanced ultra-precision grinding technology will enhance machining accuracy even without the need or with less need for subsequent lapping and polishing. So it has important practical significance to study the ultra-precision grinding technology of typical micro spherical and aspherical components.Firstly, the paper concluded the key technology of nanogrinding on the basis of analyzing the development state of the ultra-precision grinding technology in manufacturing micro spherical and aspherical components of super-brittle-hard materials. Then proper grinding methods were determined on the basis of analyzing the typical processing methods that are applied to manufacturing micro spherical and aspherical components in detail and combining the structural characteristics of the workpieces: TN85 hemisphere couples were processed by combining form grinding with wheel normal grinding methods and tungsten carbide workpieces and aspherical optical glass workpieces were processed by wheel normal grinding method.Secondly, study on the truing and dressing experimental of diamond wheel was carried out to solve the problems like the worse of surface accuracy caused by wheel wear in ultra-precision grinding. The required dimensional accuracy and grit protrusion were obtained from dressing the wheel's circumference and radial direction by the rolling method. Besides, proper rough and fine grinding parameters were determined,according to material properties, machine tool accuracy and the structure of workpiece, which were applied to the grinding experiment of TN85 hemisphere couples, tungsten carbide die and hard-brittle glass in combine with the on machine measurement and compensation technology. The results showed that the surface roughness of nanometer grade and the profile accuracy of sub-micron grade could be obtained by the determined grinding method and parameters.Finally, the surface micro-topography analysis of the workpieces showed that the material properties like microstructure and hardness were the crucial factors that affected the surface quality of the workpieces and the relative velocity of the machining point on the surface also had a great effect on the surface quality. Besides, the study of the wheel wear and its influence on the surface accuracy in the process of grinding micro spherical and aspherical components showed the types of binding types and material properties like hardness and microstructure had a great effect on the life and main wear types of wheel. Moreover, the resin bonded diamond grinding wheel need to be dressed regularly because of the dimension change caused by wheel wear would have a bad effect on the surface accuracy of workpieces.