Behavior and Control of Molten Cladding - Modeling of Joint Formation in Aluminum Brazing

本研究项目将对铝合金可控气氛钎焊液态金属阶段的接头形成和材料行为进行研究。调查将是实验的、分析的和数值的。它将寻求：(1)建立接头形状的拓扑模型；(2)量化实际焊接条件下微槽和表面粗糙度对熔覆层流动的影响；(3)建立一种新的熔覆层流动控制方法，该方法将足够稳健地应用于工业。广泛的实验研究将包括汽车、飞机、低温和空调/制冷行业中使用的复杂的板翅式换热器样品。在这项研究中，在具有可控气氛功能的特殊透明真空炉中，在计算机引导的热状态期间，将使用高速数码相机成像来实现对熔融金属相的现场监测。实验条件将与实际焊接过程中的条件相同。实验研究的目的是清楚地显示和了解熔融金属的流动和接头形状的形成。理论分析将利用表面张力理论来定义熔融金属膜在凝固开始时的平衡轮廓。数值分析将使用参数有限元方法进行。

This research project will investigate joint formation and material behavior during the liquid metal phase of controlled atmosphere brazing of aluminum alloys. The investigation will be experimental, analytical and numerical. It will seek to: (1) model the topology of the joint shape; (2) quantify the influence of micro grooves and surface roughness on the cladding flow under actual brazing conditions; and (3) establish a new method for control of molten cladding flow which will be sufficiently robust to be applied in industry.The extensive experimental study will include the complex plate-fin heat exchanger samples used in the automotive, aircraft, cryogenics and air-conditioning/refrigeration industries. In this study, in-situ monitoring of the molten metal phase of the process will be achieved using high-speed digital camera imaging during the computer guided thermal regimes in a special transparent vacuum furnace with controlled atmosphere capabilities. The experimental conditions will be identical to the conditions in an actual brazing process. The objective of the experimental study is to clearly visualize and understand the molten metal flow and joint shape formation. Theoretical analysis will utilize surface tension theory to define an equilibrium molten metal membrane profile at the onset of solidification. Numerical analysis will be performed using a parametric finite element method.