Research On The Mechanism And Technology Of Laser Polishing H11 Die Steel

Laser polishing(Laser Polishing)technology is a widely used special processing technology,which can realize non-contact processing of polishing equipment and materials,and has the advantages of high polishing efficiency,low pollution,high precision and wide application range.In this paper,H11 die steel is used as the experimental material,and a two-dimensional finite element transient numerical model of laser polishing die steel is established by combining numerical simulation and experimental analysis,simulating the changing law of the surface morphology during the polishing process,and analyzing its polishing mechanism;Carry out experimental research on the polishing process of die steel,explore the influence of laser parameters on the polishing effect,and conduct specific research on the phenomenon of micro-cracks after polishing.The main research contents of the paper are as follows:First,the specific process of laser polishing is discussed.The interaction process between the laser beam and the processing material is analyzed in detail from both macroscopic and microscopic aspects;the specific changes and causes of the material are explained,and the Gauss laser heat source is selected and specific parameters are set to establish a two-dimensional instantaneous laser polishing process.state numerical model.Secondly,the simulation study of the polishing process is carried out.The COMSOL software is used to simulate the instantaneous temperature field and flow field in the polishing process,and the simulation results of three laser parameters of different laser power,scanning speed and pulse width,and two process parameters of different initial surface roughness and scanning times are obtained.The temperature change law of the material surface,the melting flow,and the vaporization removal phenomenon are analyzed.Again,build a specific experiment of laser polishing H11 die steel.Under the single-factor experiment method,the influence of four laser parameters of different laser power,scanning speed,defocusing amount,pulse width and different initial topography on the polishing effect was studied.The best polishing effect is obtained when the speed is 90mm/s,the defocusing amount is 3.5 mm,and the pulse width is 130 ns.The mechanism of laser polishing is summarized based on the simulation and experimental results,which verifies the feasibility of the laser polishing technology.Finally,the generation of microcracks during laser polishing is investigated.Through the simulation results of the temperature field and stress field at different node positions of the polishing model,the mechanism,influencing factors and prevention methods of microcracks are obtained,and specific polishing experiments are carried out to verify the accuracy of the model.The experimental study of cracks found that power has a great influence on the generation of micro-cracks;the observation experiment was carried out on the sub-surface of the polished material to explore the damage to the interior of the material caused by the phenomenon of micro-cracks.Micro-cracks can be effectively prevented through the preheating process;the hardness test experiment was carried out,and the surface hardness of the material after polishing was significantly improved,which further verified the rationality of the laser polishing technology.