为了在模具上加工出特定的毛化形貌和尺寸,采用计算流体力学软件Fluent探究形貌成型机理,建立了激光毛化过程3维瞬态模型.考虑热传导、热对流、材料热物性参量等影响因素,采用焓法处理固液相变移动边界,通过用户自定义函数加载激光热源,计算得出熔池温度场与流场.基于数值模拟,采用单因素轮换法进行了毛化工艺试验,研究了激光功率密度、脉宽两因素对毛化形貌、几何参量的影响.结果表明,激光功率密度在2.04×104 W/mm2~3.57×104 W/mm2,脉宽在100μs~1000μs之间;以氮气作为辅助气体,可获得球冠状、凹顶球冠状、M状3种形貌.该结果对模具毛化种类具有指导意义.%In order to fabricate specific morphology and size on a mold by means of the laser texture , and explore the mechanism of the formation of topography , a three-dimensional transient model of the laser texturing process was established based on the Fluent software.The temperature field and flow field of molten pool were calculated , and the experimental parameters were determined:laser power density 2.04 ×104 W/mm2 ~3.57 ×104 W/mm2 , pulse width 100μs~1000μs.The thermal conductivity , thermal convection , thermophysical properties of materials and other factors were considered.The enthalpy method was used to deal with the boundary of solid-liquid phase transition , the laser heat source was loaded through user defined function.Based on numerical simulation , the influence of laser power density and pulse width on the morphologies and geometrical parameters of laser texturing were studied by varying a single factor with nitrogen gas as the auxiliary gas.Spherical crown, concave crown and M shape were obtained.The results have guiding significance for mold texturing.
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