尼龙6粉末选区激光烧结中能量累积的数值模拟与实验研究

Numerical simulation and experimental study on energy accumulation effect in selective laser sintering of nylon 6 powder

选区激光烧结的逐行逐层的增材制造是一个能量的持续作用过程。对不同的线能量密度、不同预热温度的尼龙6粉末烧结过程进行建模和仿真,结合反映烧结样品热氧老化程度的黄蓝指数b^(∗)值的测量,对烧结过程的能量变化进行了分析。结果表明:不同线能量密度的单层烧结,连续5行扫描烧结区能量增加约3.4%~7.82%,扫描能量较小时累积较为明显;预热温度从25℃增加到180℃时,烧结区能量的增幅为9.17%~5.66%;多层烧结中10层以下能量累积较快,增幅为11.66%,10~20层仅增大0.67%;虽然均表现出由于热平衡而使得在较高能量下的累积减缓,但是,实验烧结样品外观的黄蓝指数测量显示,对应b^(∗)值从25℃的2.15增大到180℃的11.65;烧结4~20层时则由6.81上升到31.02,样品黄色程度在加深,表明烧结样品的热氧老化也越严重;故了解烧结过程的能量变化及相关工艺参数优化,将有助于提高烧结样品的综合质量。

Selective Laser Sintering(SLS)is a continuous process of energy.The sintering process of nylon 6 powder with different linear energy density and preheating temperature was modeled and simulated.Combined with the measurement of the yellow-blue index b^(∗)which reflects the thermal oxygen aging degree of the sintered samples,the energy change of the sintering process was analyzed.The results show that:the energy in the sintering zone increases by 3.4%~7.82%for 5 consecutive scanning lines with different linear energy density,and the energy accumulation is obvious in the case of small scanning energy;when the preheating temperature increases from 25℃to 180℃,the energy in the sintering zone increases by 9.17%~5.66%;the energy accumulation in the multi-layer sintering is faster,with the increase of 11.66%,and that of 10~20 layers is only 0.67%.However,the measurement of the yellow-blue index of the sintered samples shows that the corresponding b^(∗)value increases from 2.15 at 25℃to 11.15 at 180℃,and increases from 6.81 to 31.02 at 4~20 layers,indicating that the thermal oxygen aging of the sintered samples is more serious.Therefore,it will be conducive to improve the comprehensive quality of the sintered samples by understanding the energy change in the sintering process and optimize the relevant process parameters.