激光熔覆多道搭接成形质量与效率控制方法

目的揭示激光熔覆工艺参数对多道搭接成形质量与效率的耦合作用规律,提高多道搭接熔覆层表面与内部组织质量及成形效率。方法采用响应面中心复合设计建立激光功率、扫描速度、气流量和搭接率与多道搭接表面平整度、熔覆效率及气孔面积之间的数学模型,通过方差分析及检验指标,验证了所建立数学模型的正确性。结果激光功率和气流量对表面平整度的值影响并不显著。表面平整度的值与扫描速度、搭接率成反比;搭接率对熔覆效率的影响较为显著,搭接率的增大使熔覆效率减小;四个工艺参数对于气孔面积都有不同程度的影响,适当增大搭接率和减小扫描速度可以减小熔覆层气孔面积。以表面平整度最好、熔覆效率最高和气孔面积最小为目标优化工艺参数,通过试验获得表面平整度、熔覆效率、气孔面积预测值与实际值的误差分别为1.36%、6.12%、7.89%,进一步验证了该模型的准确性。结论该研究成果为多道熔覆涂层质量、熔覆效率的控制与预测以及工艺参数的优化提供了理论依据。

Control of the Quality and Efficiency of Multi-track Overlapping Laser Cladding

The work aims to find out the coupling effects of the parameters of the laser cladding process on the quality and efficiency of multi-track overlapping, so as to improve the quality of the surface and the internal micro-structure of the multi-track cladded layer and the forming efficiency. The response surface methodology (RSM) was adopted to establish a mathematical model of laser power, scanning speed, gas flow, overlapping rate and flatness ratio, cladding efficiency and pore area of multi-track surface. The variance analysis and inspection indicators were used to validate the correctness of the mathematical model. Laser power and gas flow had no significant effects on the flatness ratio, while the value of flatness ratio was inversely proportional to scanning speed and overlapping rate. In addition, the overlapping rate had significant effects on the cladding efficiency and the increased overlapping rate could lower down cladding efficiency. The aforementioned four process parameters could affect pore area to different degrees. Increasing the overlapping rate and decreasing the scanning speed appropriately could reduce the pore area of the cladding layer. The processing parameters were optimized to produce the best flatness ratio, highest cladding efficiency, and the smallest pore area. The errors between the predicted value from the experiment and the actual value for flatness ratio, cladding efficiency and pore area were 1.36%, 6.12% and 7.89% respectively. The accuracy of the model was further validated. The research results provide the theoretical guidance for the controlling and prediction of the quality and efficiency of multi-track laser cladding and the optimization of process parameters.