| Face gears play a key transmission role in many aerospace,marine and other large machinery and equipment,and have a large number of advantages,but the tooth profile of the face gear is a complex surface,and the technical requirements for its fine machining are high,and the accuracy that domestic face gears can achieve is far inferior to that of foreign countries,which are blocked to China in these advanced manufacturing technologies.In order to solve this manufacturing difficulty and lack of precision,this paper adopts the method of femtosecond laser fine-machining to remove the surface margin of face gears,and studies the influence law of femtosecond laser parameters and processing process parameters on face gear tooth surface morphology,so as to provide a new processing method in improving the surface precision of face gears.In this thesis,the ablation mechanism during the femtosecond laser ablation of the face gear material 18Cr2Ni4 WA is studied,the mode of action of the femtosecond laser fine removal of the face gear material is analyzed,the complex physical process of the femtosecond laser ablation of the face gear material is revealed,the thermodynamic parameters that change with temperature are analyzed,and on the basis of the dual-temperature model of temperature transfer between photons and electrons and electrons and lattice A complex coupling model coupling these dynamic thermodynamic parameters is established.The three-temperature heat transfer model is established by considering the lattice-to-lattice heat transfer on the basis of the established complex coupling model.Based on the established model,the distribution law of tooth surface temperature field during femtosecond laser ablation of face gear material is obtained by finite element software calculation,which reveals the temperature transfer change process between electron lattices during femtosecond laser ablation of face gear material.The maximum temperature reached by the electrons was found to increase gradually with the increase of the femtosecond laser energy density,and the final equilibrium temperature reached by the coupling between the electrons and the lattice was also gradually increased,and the coupling time was also slightly increased;the maximum temperature of the electrons gradually decreased with the increase of the pulse width,and the ablation morphology of the material with the removal of the temperature higher than the evaporation temperature was predicted according to the temperature calculated by the complex coupling model;multi-pulse loading,with the increase of energy density,the electron maximum temperature increases and the final material surface equilibrium temperature is also increasing.The effect of the change of electron lattice temperature on the ablation morphology during femtosecond laser ablation of face gear materials is revealed.In the study of femtosecond laser scanning processing of face gears,the laser spot moving path was planned in x and y directions by analyzing the laser heat source term,and the accumulated energy intensity and distribution scale of femtosecond pulses at different scanning speeds and different pitches were analyzed by considering the multi-pulse energy accumulation effect of femtosecond laser.It was found that the accumulated energy intensity of multiple pulses decreased and the energy distribution scale increased with the increase of scanning speed and scanning pitch.The effect of the accumulated energy intensity on the ablation pattern of the face gear material during the scanning process of the femtosecond laser was revealed.The changes of the ablation profile and tooth surface roughness of face gears were analyzed by changing the laser energy density,pulse width,scanning speed and scanning pitch.The laser parameters and process parameters for femtosecond laser machining of face gear materials were optimized.These provide a research basis for improving the surface morphology quality of face gear materials processed by femtosecond laser scanning. |
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