Grinding Force Modeling And Experiment Research In Ultrasonic Vibration Grinding Of Optical Glass BK7

BK7 optical glass has excellent physical and chemical properties such as low density,high temperature resistance and corrosion resistance.But due to its high hardness and low fracture toughness,the use of traditional machining methods will result in increased cutting forces,which will adversely affect the quality and performance of the machined parts.Ultrasonic vibration grinding technology is based on the traditional grinding process to apply high frequency vibration along the axial direction of the grinding wheel,which can increase the cutting arc length,reduce the chip thickness,improve the plastic removal ratio during hard and brittle material processing,and effectively reduce the cutting force and improve the surface quality.Grinding force is one of the main factors that directly affect the removal method and surface quality of optical glass materials.The ultrasonic vibration grinding force model of BK7 optical glass was established to realize the effective prediction and control of grinding force,which had important theoretical significance and practical value for improving the surface quality and processing efficiency.In the process of ultrasonic vibrating grinding of optical glass,the distribution of the position and protrusion height of the diamond abrasive grains on the surface of the grinding wheel is closely related to the amplitude of the grinding force.In this paper,the local surface topography data of the diamond grinding wheel was obtained by laser confocal microscopy.The local surface topography data of the diamond grinding wheel was obtained by laser confocal microscopy.By processing the curvature information and noise signal of the grinding wheel in the sampled data,the characteristics of the height of the abrasive grains on the surface of the grinding wheel and the horizontal distribution characteristics were obtained.According to the above data and analysis,the surface morphology of the grinding wheel was reconstructed,and the simulation model of the grinding wheel surface was established.The reliability of the simulation model was verified by comparing the actual wheel shape data with the sampling area.The above research laid the foundation for analyzing the contact state between the abrasive particles and the workpiece,determining the cutting stage where the abrasive grains are located,and establishing the grinding force model for ultrasonic vibration grinding.According to the difference of kinematics during processing,axial ultrasonic vibration grinding can be divided into two types: side grinding and end grinding.Based on the analysis of abrasive kinematics and kinetics under ultrasonic vibration,the grinding force model of ultrasonic vibration side grinding and end grinding of BK7 optical glass was established based on the research results of the abovementioned grinding wheel morphology and abrasive grain distribution characteristics.The ultrasonic vibration side grinding force modeling mainly considered the contact state and interaction relationship between the abrasive particles and the workpiece.On the basis of the comparative analysis of the common side grinding and ultrasonic vibration side grinding elements,combined with the grinding force research of the abrasive grains in the different action stages of the material removal process,the grinding force model of the ultrasonic vibration side grinding was established.In the ultrasonic vibration end grinding force modeling process,the material removal rate model was established by analyzing the optical glass material removal method.Combined with the grinding force and impulse equalization theorem generated by a single abrasive grain,the ultrasonic vibration end face grinding force model was established.The ultrasonic vibration grinding experiment of BK7 optical glass was carried out,and the effectiveness of the grinding force model was verified.On this basis,the influence of process parameters on the grinding force wad analyzed,which provided a basis for the research of subsequent process parameter optimization.Based on the above research,based on the established ultrasonic vibration grinding force model,the optimization of the high-precision ultrasonic vibration grinding process parameters of BK7 optical glass was studied.In this paper,the nondominated sorting genetic algorithm(NSGA-II)was selected as the process parameter optimization method,and the surface quality of optical glass processing was taken as the objective function.The cutting force model and material removal rate model of ultrasonic vibration grinding were taken as the constraint function,and the process parameters were used as the decision variables.The reliability of the process parameter optimization method was verified by ultrasonic vibration grinding experiment.