Thermal Behavior Analysis And Experimental Research Of KDP Crystal Cutting Process

As an important nonlinear optical material,potassium dihydrogen phosphate（KH₂PO₄,KDP）crystals are widely used in laser and nonlinear optics,and are the only materials available for laser frequency doubling components in large laser system.In order to satisfy the requirements of high-energy laser optical path,the process of KDP crystal components need to satisfy all stringent technical indicators of the full space frequency band,and the deliquescent characteristics of the crystal materials determine that the single-point diamond fly-cutting technology is currently the most feasible processing solution.However,the KDP crystal has the characteristics of low hardness,large brittleness and strong anisotropy.At present,domestic fly-cutting process about KDP crystal component still have insufficient surface integrity.The main reason is that the crystal surface formation process in the fly-cutting and the cause of quality reduction of machined surface are not well understood.In view of this problem,this paper will study the cutting force and cutting temperature of KDP crystal fly-cutting process,and optimize the process technology based on it.The main research contents of this paper are as follows:（1）Numerical model of the KDP crystal fly-cutting process.Based on the machining mechanism of the KDP crystal fly-cutting process,the cutting force model about the fly-cutting process is improved,and the calculation method about the contact area between the rake face and the chip and the contact area between the flank face and the workpiece is improved.The cutting force variation under different cutting parameters was analyzed.Based on the heat source method and the instantaneous equivalence of the contact surface,the negative rake angle thermal model about the KDP crystal fly-cutting is established,which solves the problem about the heat distribution ratio in the first deformation zone and the second deformation zone,and realizes the calculation formula derivation about the cutting temperature.The thermal field model conforms to the actual cutting condition,which will be beneficial to the research about cutting temperature rule in the KDP crystal fly-cutting process.（2）The influence of different working conditions on cutting force and cutting temperature during KDP flying cutting process was studied.Based on the adaptive mesh technique and the elastoplastic constitutive model of KDP crystal,and the cutting process is simplified reasonably.The thermal coupled finite element model about KDP crystal fly-cutting process is established.The influence of different working conditions on cutting force and cutting temperature is calculated,the relationship between cutting parameters and cutting force and cutting temperature is obtained,and the interaction between cutting force and cutting temperature is analyzed.At last,cutting temperature and KDP chip morphology were combined to analyze the effect of cutting temperature on the KDP crystal surface and structure,which is used as a reference to optimize the parameters,and which is helpful to promote the research about cutting heat of KDP crystal fly-cutting process.（3）Experimental measurements about the cutting force and cutting temperature during the KDP crystal fly-cutting were taken.Based on the use of the acceleration sensor,the cutting force data in the KDP cutting process is obtained;Based on the use of the high-speed infrared camera,the temperature data in the KDP cutting process is obtained,then the experimental results of the cutting force and the cutting temperature are analyzed and sμmmarized.The actual influence of different cutting parameters on the fly-cutting process is compared with the calculation results and simulation results to verify the rationality of the theoretical calculation model and the thermo-mechanical coupled finite element simulation model.