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激光焊接由于其焊缝深宽比高、热影响区小以及高的焊接速度而在工业上得到越来越广泛的应用。激光深熔焊接的本质特征就是存在着小孔效应。采用高速摄影的方法清晰、完整地观测了激光深熔焊接GG17玻璃时的小孔,实验研究了离焦量、焊接速度对小孔和熔池形状、尺寸的影响。在分层假设的基础上建立了激光深熔焊接小孔效应的传热模型,并根据观测到的小孔形状和尺寸,用有限元法计算了小孔周围的温度场和流场。实验与模拟计算结果表明,小孔前沿的温度梯度比后沿的大;焊接熔池中的最大对流速度达到了焊接速度的10倍左右;小孔形状和尺寸的实验观测为系统研究激光深熔焊接时的小孔效应提供了一种新的方法。
Laser welding is widely used in industry due to its high aspect ratio, small heat-affected zone and high welding speed. The essential feature of laser deep penetration welding is the existence of pinhole effect. The method of high-speed photography was adopted to clearly and completely observe the small holes when laser deep-welding GG17 glass. The effects of defocus amount and welding speed on the shape and size of holes and puddle were studied experimentally. Based on the assumption of layering, the heat transfer model of laser deep hole welding was established, and the temperature field and flow field around the small hole were calculated by the finite element method according to the shape and size of the hole. The experimental and simulation results show that the temperature gradient of the leading edge of the small hole is larger than that of the trailing edge. The maximum convection velocity in the welding pool reaches about 10 times of the welding speed. Experimental observation of the shape and size of the hole is a systematic study of laser deep melting Hole effect when welding provides a new method.