Study On Processing Technology And Mechanism Of KDP Crystals Surface Generation During Fly-cutting Process Assisted By Oil Lubrication

KDP crystal is mainly used in inertial confinement fusion and solid-state laser system,but KDP crystals are low brittleness,easy deliquescence,anisotropy and temperature sensitivity,which is recognized as a typical material which difficult to process in the world.At present,the single point diamond flying cutting technology is mainly used to process KDP crystals.However,the cutting heat produced in the machining process will seriously make effects on the surface quality and surface integrity of the workpiece,which seriously effects the output power and service life of the laser.At present,there is a lack of systematic research on the diffusion mechanism of the cutting heat in the flying cutting process of KDP crystal.The mechanism of the influence of cutting heat on the surface quality of workpieces is not clear.To further improve the efficiency and high surface integrity of KDP crystal has become a bottleneck in the field of inertial confinement fusion and solid-state laser element manufacturing.This paper analyzes the influence of cutting oil on the surface quality of KDP crystal during flying cutting.Based on the mechanical properties of KDP crystal and the characteristics of flying cutting,the cutting force in the flying cutting process is analyzed and calculated;based on the principle of heat diffusion and fluid convection heat transfer,the temperature field in the process of KDP crystal dry flying cutting and oil assisted flying cutting is analyzed;based on the characteristics of flying cutting and the distribution of temperature field,the surface morphology model of KDP workpiece was established under the conditions of dry-type flying cutting and oil lubrication assisted flying cutting..When analyzing the cutting force in KDP crystal flying cutting process,because the material is brittle material,the elastic region,plastic region and brittle region of the cutting section are divided.The cutting force under quasi-static condition is calculated according to the difference of cutting forces in different regions.Based on Johnson cook model,the cutting force model considering high strain rate is established.In the process of machining,it is assumed that all mechanical energy is converted into internal energy.Based on the cutting force model under the condition of high strain rate and the actual machining situation in the process of flying cutting,the mathematical model of heat flux is established.Based on the material properties of KDP crystal and the technology of flying cutting,the cutting heat diffusion model of KDP crystal is established.Considering the anisotropy of the material and the convective heat transfer with the external fluid,based on the law of conservation of energy and the law of Fourier heat transfer,the temperature field model and chip temperature field model of KDP crystal workpiece under the conditions of dry flying cutting and oil assisted flying cutting are established.According to the temperature field model,considering the change of material size caused by the change of temperature,the surface morphology model of KDP workpiece was established under the conditions of dry-type flying cutting and oil lubrication assisted flying cutting.