Design And Application Of Small Selective Laser Melting

Selective laser melting technology(Selective Laser Melting,SLM),one of the most promising technologies for metal parts,has been widely used in the fields of special machinery,aerospace,biomedicine and so on in recent years.In order to meet the demand of open scientific research experiment,this paper designs and develops a compact small SLM equipment with remarkable cost advantage based on the principle of SLM.The 3D printed metal structure parts with good formability have been obtained by the small SLM,and the related properties and mechanism have been studied.In this paper,the overall architecture scheme of small SLM equipment is designed,and the equipment is divided into four systems:the powder feeding-powder laying system,the laser scanning system,the control system and the gas protection system.The optimization design of the structure and the selection of the components are carried out respectively:1)In order to realize the design goal of structure compactness,a powder feeding box with leaky groove is designed and placed in the back and top of the forming cylinder of the parts to improve the internal space utilization rate of the equipment.Through developing powder-laying mechanical movement device,the amount of powder falling can be controlled accurately to improve the utilization ratio of powder.2)The controllable focusing device is introduced into the laser scanning system.The gear-worm mechanism and gear-rack mechanism are used to realize the adjustment of the laser spot size for the different material powders.3)In order to further improve the compactness of the equipment volume,the control system is integrated into the lower cavity of the equipment.4)The atmosphere protection system is optimized by fluent numerical simulation,and the optimal arrangement scheme of gas filter and atmosphere cavity structure is obtained.In order to meet the needs of small,special-shaped or complex components aerospace parts,the process of GH3536 nickel-based superalloy was studied by using the small SLM equipment designed in this paper.The effects of different laser scanning strategies(inclined partition canning,corkscrew spin scanning,island shape scanning)on the density,microstructure and properties of GH3536 nickel-based alloy forming parts were compared.According to the experimental results,the inclined partition is selected as the best scanning strategy.The Gyroid minimal curved surface structure specimen is fabricated.Combined with the geometric parameters,the compression performance of the Gyroid structure is analyzed.The results show:The compression curve of the Gyroid structure with smaller wall thickness shows good energy absorption at the plastic stage,and the compression performance of the Gyroid structure in the building direction is higher than that in the horizontal direction under the same wall thickness.