Numerical Simulation And Experimental Study Of Laser Cutting NdFeB Magnetic Materials

NdFeB magnetic material is the most powerful permanent magnet material so far,with high magnetic energy product,high remanence density,high coercive force and other high-quality characteristics.It is widely used in energy,transportation,machinery,medical,IT and other industries.With the continuous improvement of science and technology and the expansion of the manufacturing industry market,NdFeB magnetic materials have new development space in more fields,and the demand is greatly increased.At present,the processing of NdFeB magnetic materials is still more traditional methods such as cutting,drilling,grinding and wire-EDM,etc,which is inefficient.Laser cutting is a new type of processing method that its unique non-contact and high efficiency,and other advantages stand out.The thermal effect of the laser is embodied in the changes of temperature and stress during the cutting process,which has certain influence on the cutting quality and material structure.The material properties could be affected by the change of structure.Therefore,the mechanism of laser cutting NdFeB magnetic materials is studied comprehensively and deeply.The study is mainly carried out from three aspects of numerical simulation,experimental research and microstructure and performance.The specific content is as follows:Firstly,the influence of temperature change in the internal structure of NdFeB material is reflected from the fracture and disintegration of the magnetic domain inside the material during the analysis process of laser cutting.The finite element model of laser cutting NdFeB magnetic material is established in ANSYS software.The distribution of temperature field and the law that processing parameters impact on the temperature field was obtained.The maximum temperature of laser cutting is concentrated on the center of the heat source.The temperature increases with the increase of laser power and pulse width,and increases with the decrease of cutting speed.The indirect method is used to get the stress field distribution and law of change.It is found that the maximum stress and deformation are concentrated in the direction of the heat source moving forward,and the law of change is the same as the temperature field.Secondly,the experiments of laser cutting 2mm thick NdFeB magnetic materials were carried out under the action of different types of auxiliary gases?N₂ and O₂?.The effects of different auxiliary gases and processing parameters on cutting quality and influence law are studied by d means of slit width,slag amount,inclination angle and surface macroscopic topography.It is found that the cutting quality is better when nitrogen is used as auxiliary gas by comparison of the experimental results,and the law that processing parameters impact on cutting quality is obtained.The data of experimentally measured slit width is compared with the results of the simulation analysis verifies accuracy and reliability of the simulation analysis.Finally,we analyse the microstructure and topography of laser-cut NdFeB magnetic material in the slit area comprehensively from the aspects of solidification mode,element content,and microhardness in order to study in depth the cutting quality of laser-cut NdFeB magnetic materials and the evolution of the shape of the slit during the cutting process.The surface topography,tissue components,element content,and microhardness of the remelted layer and heat-affected zone are different from those of the substrate from micro perspective.The surface topography of the remelted layer under nitrogen is less oxidized and ablated.Content of O element is lower,the surface topography and grain size distribution of the cut surface are more uniform,and laser power and pulse width have a certain effect on microstructure.The microhardness decreases from 575HV to 530HV gradually from the remelted layer to the substrate.