选择性激光烧结初期卷曲控制实验

Experiment of Curling Control in Initial Stage of Selective Laser Sintering

为改善选择性激光烧结工艺中无法消除的初期卷曲,通过在烧结件底部外围设置围裙来间接控制烧结热影响区的温度场,降低初期卷曲。在SLS-300成形机上完成了卷曲控制实验,所用工艺参数为:激光功率P=27 W,扫描速度v=1800 mm/s,扫描间距d=0.39 mm,层厚h=0.25 mm,预热温度T_(0)=75℃;围裙参数为:高度a=2.0 mm,底厚b=0.5 mm,边距c=5.0 mm,水平间隙e=0.4 mm,竖直间隙f=0.5 mm;建造材料为粒径120μm的聚苯乙烯粉。接着对围裙法烧结件和原始烧结件进行3D扫描,在Geomagic上完成3D重构,并分析其偏差;最后通过计算重构件侧面轮廓边线的算术平均值,评估其几何误差。结果表明,与原始烧结件相比,围裙法烧结件的3D偏差平均降低47.64%,2D偏差平均降低67.93%。烧结件的轮廓直线度平均提高73.99%;底部粉末覆盖面积比增加12.86%。

In order to improve the initial curl that cannot be eliminated in the selective laser sintering process,an apron was set at the periphery of the bottom of the sintered part to indirectly control the temperature field in the sintering heat affected zone and reduce the initial curl.The curl control experiment was completed on SLS-300 forming machine.The sintering process parameters were as follows:laser power P=27 W,scanning speed v=1800 mm/s,hatching distance d=0.39 mm,layer thickness h=0.25 mm,preheating temperature T_(0)=75℃;Apron parameters∶height a=2.0 mm,bottom thickness b=0.5 mm,edge distance c=5.0 mm,horizontal clearance e=0.4 mm,vertical clearance f=0.5 mm;The construction material was polystyrene powder with particle size of 120μm.Then,the apron sintered part and the original one were scanned in 3D,the 3D reconstructions were completed on Geomagic,and theirs deviation were analyzed;Finally,the geometric errors were evaluated by calculating the arithmetic mean of the side contours of the reconstructed parts.The results show that compared with the original part,the average 3D deviation of apron sintered part is reduced by 47.64%and the 2D deviation is reduced by an average of 67.93%.The contour straightness of sintered part is increased by 73.99%on average.The surface coverage area of the bottom profile is increased by 12.86%.