石墨/酚醛树脂混合粉末选择性激光烧结成型精度实验研究

Experimental Study on Molding Precision for Graphite/Phenolic Resin Mixed Powders Processed by Selective Laser Sintering

将选择性激光烧结(SLS)技术应用于石墨/酚醛树脂混合粉末成型,实验研究了石墨原型件尺寸精度的变化规律,并揭示了其内在原因。研究发现,石墨原型件X、Y方向的尺寸偏差随着激光能量密度的增大而增大,随着分层厚度的增大而减小,而Z方向的尺寸偏差随着激光能量密度和分层厚度的增加呈现出先减小后增大趋势;与X、Y方向尺寸相比,Z方向尺寸受工艺参数的影响更为明显。导致石墨原型件产生较大尺寸偏差的主要原因是SLS成型过程中产生了较为明显的次级烧结和Z轴盈余。正交实验结果表明,影响Z方向尺寸相对误差的因素按影响程度从大到小排序依次为扫描间距、分层厚度、激光功率、扫描速率。使Z方向尺寸相对误差最小的最优工艺参数组合为:激光功率23 W、扫描速率1000mm·s^(-1)、扫描间距0.18mm、分层厚度0.14mm。

The selective laser sintering （SLS） technology is applied to the molding of the graphite/phenolic resin mixed powders, the change rule of the dimensional precision of the graphite prototype is studied experimentally, and its internal cause is revealed. It is found that the dimensional deviations in both the X and Y directions of the graphite prototype increase with the increase of the laser energy density, and decrease with the increase of the layer thickness. The dimensional deviation in the Z direction shows a tendency to decrease first and then increase with the increase of the laser energy density and the layer thickness. Compared with the dimensions in the X and Y directions, the dimension in the Z direction is more obviously affected by the process parameters. The main reasons for the large dimensional deviation of the graphite prototype are the secondary sintering and the Z axis bonus, which are produced in the SLS process. The orthogonal experimental results show that the factors affecting the relative dimension error in the Z direction are sorted by the order of influence degree from large to small as the scanning interval, the layer thickness, the laser power and the scanning speed. The optimal combination of process parameters which makes the relative error in the Z direction smallest is： laser power of 23 W, scanning speed of 1000 mm·s^-1, scanning interval of 0.18 mm and layer thickness of 0.14 mm.