Research On Surface Creation And Subsurface Damage In Ultrasonic Vibration Grinding Of Optical Glass

In recent years, with the rapid development of electronic technology, aerospace technology, optical communication technology, atomic energy technology and laser technology and other cutting-edge technology, the performance requirements of optical materials are also getting higher and higher. As the optical glass material has many advantages such as: more accurate optical constants, stable performance of the structure, could achieve a variety of optical functions and so on, it could be widely used in the field. At the same time, as a kind of hard brittle material, also it possess the characteristic of high hardness, high brittleness, low fracture toughness and poor machinability. If we use the traditional processing method such as grinding, lapping or polishing, it would be difficult to make the machining efficient, cheap and get better quality of the surface at the same time.With the development of precision machining technology, ultrasonic vibration grinding technology has gradually being one of the methods for precision machining of optical glass because of its advantages of high efficiency and low damage. In this paper, the simulation model of the surface roughness of optical glass ultrasonic vibration grinding is established, and combined with the experimental data to verify and revise the model. The formation mechanism of subsurface damage in ultrasonic vibration grinding of optical glass has been analyzed. The influence of processing parameters on the surface roughness and subsurface damage has been studied. It provided the basis to the technical measures for the reduction of sub surface damage.In the practical application of optical glass, the requirement of surface roughness is higher, so the research on the influencing factors and the law of the surface roughness is the basis of improving the surface quality of the machined surface. In this paper, the surface topography of the grinding wheel was sampled, and the digital information of the sampling area was obtained. Through the processing and calculation of the sampled data, the simulation model of the surface topography of the grinding wheel was built, the validity of the simulation model was verified by comparing the measured results with the simulation results of the surface topography of the grinding wheel. The random arrangement of the abrasive grains on the surface of the grinding wheel was analyzed and calculated. Based on the motion analysis of ultrasonic vibration grinding, the space motion equation of any particle in the machining process was established. It provided a foundation for the establishment of the prediction model of surface roughness in ultrasonic vibration grinding of optical glass.On the basis of the above research, the prediction model of machining surface roughness was established by using the surface profile search algorithm, MATLAB software was used to predict the surface roughness of the machined surface. The ultrasonic vibration grinding experiment of optical glass BK7 was done. The validity of surface roughness prediction model was verified and modified. The influence of ultrasonic vibration parameters and grinding parameters on the surface roughness was studied, in order to provid the basis for the selection of the process parameters of the low surface roughness ultrasonic vibration precision grinding of optical glass.The sub surface damage caused by optical glass directly affects the performance and service life of the workpiece. In this paper, the mechanism and characteristics of the surface damage of the optical glass in the process of ultrasonic vibration grinding were analyzed. Mechanical polishing method was used to deal with the processing of the processed workpiece with HF acid corrosion, scanning electron microscopy was used to observe the surface and cross section of the process. The cause of crack was analyzed according to the characteristics of sub surface damage. The influences of processing parameters such as spindle speed, feed rate, grinding depth and ultrasonic vibration amplitude on the maximum crack depth of subsurface damage were studied experimentally. It provided the basis for the exploration of the technical measures for the reduction of subsurface damage.