应用激光, 2018, 38 (4): 511, 网络出版: 2018-10-06
激光增材制造中已成形截面对粉末浓度的影响
Effects of Formed Cross Sections on Powder Concentration in Laser Additive Manufacturing
薄壁结构 粉末浓度 熔覆层截面 同轴激光熔覆 thin-walled structure powder concentration cladding layer section coaxial laser cladding
摘要
薄壁成形一直是增材制造中的研究难点, 建立了粉末浓度和熔覆层截面形状的关系模型来研究增材制造中已成形的熔覆层对粉末浓度的影响, 而粉末浓度的变化会影响沉积实体的尺寸和形状精度。结果表明, 不同的熔覆层形貌会导致不同的粉末浓度分布, 从而进一步影响横截面轮廓。在搭接区域由于熔覆层截面轮廓的切向角, 粉末浓度在搭接区域的底部突然减小。沉积熔覆层的宽度与高度的比较大所引起的粉末浓度的增加小于较小宽高比的影响。粉末浓度的变化也会影响熔覆层的宽度和高度。另一方面, 由于粉末浓度的增加, 吸收了更多的激光能量, 导致激光能量密度在搭接的区域下降, 产生孔洞等缺陷。增大熔覆层的宽高比可以减小已成形的截面形状对粉末浓度的影响, 从而减少缺陷, 同时也能减少孔隙的产生, 实验也证实了这一点。
Abstract
Deposition of thin-wall has always been a research difficult in additive manufacturing. A relationship model of powder concentration and cladding layer cross-section profile has been developed to investigate the effects of formed cladding layer on the powder concentration in additive manufacturing, and the change in powder concentration affects the size and formation accuracy of the deposited parts. The results show that different cladding morphologies will result in different powder concentration distributions that further affecting the cross-section profile. The powder concentration suddenly decreases at the bottom of overlap region because of the tangential angle of the cross-section profile of the cladding layer. The increase in powder concentration caused by larger ratio of width to height of the deposition cladding layer is less than the effect of a smaller aspect ratio. Changes in powder concentration also affect the width and height of the cladding layer. On the other hand, due to the increase of the powder concentration, more laser energy is absorbed, which leads to the drop of the laser energy density in the overlapping area, resulting in defects such as holes. Increasing the aspect ratio of the cladding layer can reduce the influence of the formed cross-section on the powder concentration, thereby reducing the defects and also reducing the generation of voids. Experiments have also confirmed this.
姚银, 宋立军. 激光增材制造中已成形截面对粉末浓度的影响[J]. 应用激光, 2018, 38(4): 511. Yao Yin, Song Lijun. Effects of Formed Cross Sections on Powder Concentration in Laser Additive Manufacturing[J]. APPLIED LASER, 2018, 38(4): 511.