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

本研究项目将研究控制气氛钎焊铝合金液态金属阶段的接头形成和材料行为。调查将包括实验、分析和数值。它将寻求：(1)建立关节形状的拓扑模型；(2)量化了实际钎焊条件下微槽和表面粗糙度对熔层流动的影响；(3)建立了一种新的熔包流控制方法，该方法具有足够的鲁棒性，可用于工业生产。广泛的实验研究将包括用于汽车，飞机，低温和空调/制冷行业的复杂板翅式热交换器样品。在本研究中，将使用高速数码相机成像，在计算机引导的热状态下，在具有可控气氛能力的特殊透明真空炉中，对该过程的熔融金属相进行现场监测。实验条件将与实际钎焊过程中的条件相同。实验研究的目的是清晰地可视化和理解熔融金属流动和节理形状的形成。理论分析将利用表面张力理论来确定凝固开始时的平衡熔融金属膜轮廓。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.