【作者】 于君；

【导师】 黄卫东；

【作者基本信息】 西北工业大学 ， 材料加工工程， 2007， 硕士

【摘要】 激光快速成形技术始于二十世纪九十年代末，到目前为止，已经在设备、材料等方面有了快速的发展，并开始应用于航天、航空等领域。为了满足其成形零件表面质量、尺寸精度的要求，需要建立该技术的实时监测与闭环控制系统，因此，获得激光快速成形工艺参数与沉积层几何参数之间的定量关系就显得非常重要。本文通过回归正交试验设计，建立了逐步线性回归模型，得到了对于沉积层几何参数具有显著性影响的工艺参数以及它们之间的定量关系。在闭环控制系统中，调整显著性工艺参数将提高系统的响应速度，减少响应时间。同时，在该系统中应用沉积层几何参数和显著性工艺参数之间的定量关系作为调整依据有利于提高成形精度。取得的主要成果如下： 1．揭示了激光快速成形工艺参数对沉积层几何参数的影响规律，并引入能量密度和功率密度两个物理量，考察了它们对沉积层几何参数的影响规律。发现：对于沉积层高度和宽度，在激光能量满足的条件下，扫描速度的影响是不可忽略的，且其影响比激光功率的影响显著，因此扫描速度是激光快速成形闭环控制中最重要的调整参数。 2．结合正交试验和回归分析的优点，设计了回归正交试验。并利用统计产品与服务解决方案（SPSS）分析回归正交试验结果，建立了逐步线性回归模型，得到了对沉积层几何参数具有显著性影响的因素。激光快速成形过程中，在激光能量满足的前提下，对沉积层高度影响最显著的因素是送粉率和扫描速度，对单道沉积宽度影响最显著的因素是光斑直径、扫描速度、激光功率与光斑直径的交互作用。同时获得了显著性影响因素与沉积层参数的定量关系：Hc₁=0.646-0.00165V+0.0391F；Hc₂=1.322-0.00284V+0.0488F；Hc₃=1.543-0.00384V+0.0938F；Hc₄=1.924-0.00460V+0.1156F；Hc₅=2.387-0.00569V+0.1459F；W=-0.184+1.2895 D-0.0013V+0.0011 P-0.0005 P*DΔHc=0.4774-0.001138V+0.02918F更多还原

【Abstract】 Laser rapid forming (LRF) has been investigated since 1990’s. By far, many equipments and materials of LRF have been developed, and LRF also began to be used in the aeronautics and astronautics fields. In order to control the surface quality and dimensions precision of LRF parts, real-time monitoring and closed-loop controlling system should be built up, which result in that it is important to obtain the relationship between processing parameters and dimensions characteristic. In present work, stepwise linearity regression model has been built up by using Orthogonal regression design (ORD) method, the most effective factors of processing parameters on the dimensions of deposition layers and the approximate relations between them have been obtained, respectively. The main results are as follows:1 The influences of processing parameters on the dimensions of deposition layers have been obtained. Energy density and power density have been introduced, and the relations between dimensions of deposition layer and these two physical quantities have been studied, respectively. The following results are achieved: the influence of scanning speed on the height and width of deposition layer is remarkable, even more notable than laser power. Therefore, scanning speed is the most important adjustable factor in the process of LRF.2 Combining the advantages of orthogonal test and regressing analysis, orthogonal regression experiments have been designed. The results have been analyzed by Statistical Product and Service Solutions (SPSS). Then stepwise linearity regression model was obtained. Powder feeding rate and scanning speed are the most effective factors on the height of deposition layers. Spot diameter, scanning speed and interaction between laser power and spot diameter are the most effective factors on the width of deposition layers. The approximate relations between them are obtained, respectively.更多还原