The Design,simulation And Manufacturing Of Industrial Filters Fabricated By Laser Powder Bed Fusion

As a flexible and powerful metal additive manufacturing technology,Laser powder bed fusion(LPBF),can directly manufactures metal parts with complex structural features and good mechanical properties with high precision,and has the characteristics of multiple metal types and high processing efficiency.The traditional metal filter is restricted by subtractive manufacturing processes,so it is difficult to improve the filter structure according to the fluid movement.LPBF technology greatly improves the design freedom of the complex model,especially for the needs of traditional metal filter optimization structure.Through the research of flow field simulation and structure optimization in the filter based on computational fluid dynamic(CFD)technology,the filter structure with low pressure drop is designed.Combining with the characteristics of LPBF technology,the filter design rules based on LPBF are proposed.In order to improve the forming accuracy and surface quality of the filter’s micro structure,the LPBF process parameter optimization and post-treatment process are studied,and finally the additive manufacturing of the filter with low flow resistance is realized.The main research contents are as follows:1)Four design methods of filter structure for LPBF process are proposed.Firstly,four kinds of last chance filters are designed.Secondly,three kinds of cell structures,“cross”,“star” and “vintiles”,are proposed and the filter structure design method of array cell is shown.Then,the filter design method of gradient node number is proposed for the case that the element is stretched to fit different pipe sections.Finally,the design method of Voronoi random porous structure filter based on the projection method of expansion surface is presented.2)The LPBF process of porous filter is studied,and the window of process parameters of various materials and the density of parts corresponding to parameters are defined.Secondly,through the typical characteristics test of porous structure,the minimum machining wire diameter and mesh size are defined,and the design rules of porous filter structure parts based on LPBF technology are summarized.Furthermore,the method of reducing laser energy is studied to obtain porous structure directly by controlling LPBF process parameters.Finally,the forming effect and processing defects are analyzed,and the size accuracy and surface morphology of the filter manufactured by LPBF are improved by the post-treatment methods such as sandblasting.3)The pressure drop test of the last chance filter and node gradient filter manufactured by LPBF is carried out.The flow process of fluid in the filter is studied by CFD method.The pressure drop test results of CFD simulation are compared with the experimental values to verify the rationality of simulation settings.Then the influence of post-treatment of sandblasting on the pressure drop of filter is studied.Finally,the air permeability of the porous filter structure controlled by LPBF process is tested preliminarily,and it is proved that the porous structure with internal pore interconnection can be manufactured by this method.4)Four kinds of industrial filters are designed and manufactured according to the specific application scenario,and they are installed for trial,which provides reference for the engineering application of LPBF technology.