The Design Of Laser Additive Sintering Machine And Study On Heat Flux Coupling And Thermal Stress

With the rapid development of modern manufacturing industry and the continuous improvement of consumer demand for product efficiency,precision and personalization,parts processed by traditional manufacturing methods can no longer meet the requirements.In additive manufacturing,laser additive manufacturing has gradually developed and matured,and Laser Direct Rapid Prototyping(LDRP),which combines Laser Cladding Forming(LCF)with Selective Laser Sintering(SLS),has gradually become a frontier research focus.The factors affecting the forming quality of metal parts in Laser Direct Rapid Prototyping are complex,including laser power,scanning speed,spot diameter,fluid temperature and flow rate,laser sintering machine materials and the coordination between motion systems,etc.The five-axis linkage machine tool designed in this paper can avoid the appearance of "step pattern" and reduce the surface roughness of parts by realizing the five-axis random linkage.According to the design requirements and the working process of five-axis linkage machine tool,the design of laser sintering machine,direct-drive type double turntable and machine body is completed,analyzed and designed the powder feeding system,the light powder coupling system,the beam focusing system,the powder flow focusing system and the cooling system,through calculation to solve the complete laser generator type selection,the determination of power plant and the design of the locking device,and establish the three-dimensional model.According to the forming method of Laser Direct Rapid Prototyping and the characteristics of actual machining process,a suitable heat source model was selected and the temperature control equation was determined according to the laser energy conduction and heat transfer mode.Combined with the characteristics of fluid flow,the fluid mathematical model is established.According to the theory of thermoelastic mechanics,the thermal stress and strain are solved,which provides the theoretical basis for the analysis of flow field,temperature field and thermal stress field.For laser sintering machine in high energy laser beam and the cooling system under the action of deformation and powder caking problem affecting the quality of molding,such as by ANSYS Fluent software to simulate different laser processing parameters and fluid parameters on the laser sintering machine was the influence law of flow field,temperature field,choose reasonable parameters in order to improve the quality of molding,and lay the foundation for the analysis of thermal stress.Precise simulation of the molding process is achieved by using ANSYS Workbench Life and Death Unit technology and ANSYS Parametric Design Language(APDL).By analyzing the thermal stress,thermal strain and the reason of residual stress and reduce the way,the transient thermal analysis of node as the node load act on the laser sintering machine temperature apparatus to analyze the transient thermal stress,thermal strain,and analyze the laser sintering machine is the influence of different parameters on the thermal stress,and then select a reasonable parameter to reduce the thermal stress,to ensure that the laser sintering machine apparatus that can guarantee in the working process of the forming precision.