Study on thermal field in fly-cutting process of DKDP crystal

As an important nonlinear optical material, deuterated potassium dihydrogen phosphate (DKDP) crystal is used in laser beams as the core element of inertial confinement fusion. The most general method to produce smooth and crack-free DKDP surface is single point diamond fly-cutting (SPDF). However, the phase-changed temperature of DKDP is only about 120 degrees C which could be exceed in fly-cutting process. To analyze temperature field in cutting process, the formula based on the heat source method was introduced to calculate the temperature values on tool rake face under different cutting speed in DKDP crystal cutting process; then, thermo-mechanical FE analysis under the same process parameters was carried out to simulate the distribution of temperature field. The calculation and simulation results are basically in agreement, and the conclusion can be deduced: as the cutting speed increases, the temperature in the cutting zone increases, the highest temperature under common cutting parameter is up to 140 degrees C, which is validated by the dynamic infrared camera; however, the cutting temperature growth rate decreases with the same trend. The experiment results indicate that the chip morphology appears small spherical structure at high cutting speed, which illustrates the great possibility that the temperature exceed the phase transition temperature.