TIG焊接过程中的熔池三维表面演化行为研究
发布时间：2018-07-24 15:39
【摘要】：熔池的表面能会反映出焊缝的成形、焊缝的外观和内在质量。因此,本文主要从TIG焊熔池表面方面展开的一系列研究工作。提出了一种熔池三维表面恢复方法。通过将结构激光投射到熔池表面,来采集结构激光随熔池表面形貌变化的反射图像。同时,建立熔池表面高度与反射激光之间的关系,通过得到的反射激光图像和对应的几何参数恢复出溶池表面三维形貌。利用这种方法能够实时的获得熔池三维表面形貌,监测熔池中液态金属流动,从而在不增加焊接生产成本的基础上提高了焊接过程的可控性,反映了更丰富的熔池表面三维信息,对获得成形美观的焊缝和提高焊接智能化具有理论和实际指导意义。首先,介绍了TIG焊熔池三维表面行为演化研究的观测试验平台,利用熔池表面类镜面反射反射特性,提出了利用结构激光投射熔池表面观测其三维形貌的方法和基于网格结构激光的TIG焊熔池三维表面的恢复算法;利用此观测方法观测了定点TIG焊熔池三维表面的演化行为,通过熔池表面的恢复算法获得了熔池表面的三维形貌。使用FLOW-3D软件建立了定点TIG焊熔池三维表面的数学模型,并进行数值分析。通过对比焊后的熔池形貌,发现试验结果和数值模拟结果基本吻合。其次,从试验角度对焊接参数阶跃(电流阶跃和速度阶跃)、脉冲TIG焊、TIG填丝焊熔滴对熔池三维表面的影响进行了探究,利用仿真和试验相结合的方法对TIG焊的熔池表面动态演化过程进行分析。结果表明:从低电流阶跃到高电流时,熔池表面变形变化不大;从高电流阶跃到低电流时,熔池表面变形发生明显的变化;阶跃电流之间的差值越大,熔池表面的变形越剧烈。从低速度阶跃到较高速度时,网格激光在熔池上的数量减少,熔池表面积先减小再增大,最后趋于稳定;从高速度阶跃到较低速度时,网格激光在熔池上的数量增加,熔池表面积增大。通过对TIG填丝焊熔池表面的分析,可以发现:焊后熔池的形貌及试验结果与恢复结果之间存在一定的误差,整体形貌相符。从数值模拟分析中得出:熔滴下落过程会引起熔池自由表面发生下凹;熔滴进入熔池,改变了熔池原有温度场和流场的分布,引起熔池自由表面发生严重的变形,使熔池自由表面随时间做阻尼振动。最后,分析了不同焊接速度对TIG焊熔池三维表面演化的影响,根据采集系统采集到的反射激光图像对不同焊接速度下的TIG焊熔池三维表面进行恢复重构并且与试验结果进行对比。为了研究快速TIG焊焊驼峰焊道的形成机理,基于FLOW-3D建立了TIG焊驼峰焊道的数学模型,分析了快速移动的TIG焊驼峰焊道温度场、流场和自由表面的变化情况,同时也分析了快速移动的TIG焊熔池表面凸起和下凹形成的原因。通过分析液态金属凝固后示踪粒子在熔池中分布情况,发现表层预先分布的粒子,熔池凝固后部分位于驼峰中,部分位于焊缝中心或者熔合线附近,由此可以得出:在TIG焊热力耦合作用下,液态金属的流动不是表面流动。
[Abstract]:The surface of the molten pool can reflect the formation of the weld, the appearance and the internal quality of the weld. Therefore, a series of research work on the surface of the TIG weld pool is mainly carried out in this paper. A method for the recovery of the three-dimensional surface of the molten pool is proposed. At the same time, the relationship between the surface height of the molten pool and the reflected laser is established, and the three-dimensional morphology of the dissolved pool surface is restored by the obtained reflected laser image and the corresponding geometric parameters. By this method, the three-dimensional surface morphology of the molten pool can be obtained in real time, and the liquid metal flow in the molten pool can be monitored without increasing the cost of the welding production. On the basis of this, it improves the controllability of the welding process, reflects the more abundant three-dimensional information on the surface of the molten pool, and has the theoretical and practical guiding significance for obtaining the beautiful weld seam and improving the welding intelligence. First, the observation test platform for the study of the three-dimensional surface behavior evolution of the TIG weld pool is introduced, and the mirror reflection reflection on the surface of the molten pool is used. The method of using the surface of the molten pool surface to observe its three-dimensional morphology and the restoration algorithm of the three-dimensional surface of the TIG weld pool based on the grid structure laser are proposed. The three-dimensional surface evolution behavior of the fixed point TIG welding pool is observed by this method, and the three-dimensional morphology of the surface of the molten pool is obtained by the recovery algorithm on the surface of the molten pool. The mathematical model of the three-dimensional surface of the fixed point TIG welding pool was established by using the FLOW-3D software, and the numerical analysis was carried out. By comparing the weld pool morphology after the welding, it was found that the experimental results were basically identical with the numerical simulation results. Secondly, the step of welding parameters (current step and speed step), pulse TIG welding, and TIG filler metal welding droplets were three The influence of the surface is explored and the dynamic evolution process of the molten pool surface of TIG welding is analyzed by the combination of simulation and test. The results show that the surface deformation of the molten pool is not very changed from the low current step to the high current; the surface deformation of the molten pool changes obviously from the high current step to the low current, and the step current is between the step current. The larger the difference, the deformation of the surface of the molten pool is more dramatic. From the low speed step to the higher speed, the number of grid laser on the pool is reduced, the surface area of the molten pool decreases first and then increases, and finally tends to be stable. The number of grid laser on the pool increases and the surface area of the molten pool increases from the high speed step to the lower speed. The surface area of the molten pool is increased. By welding the TIG filler wire, the weld pool surface area is increased. The analysis of the surface of the molten pool shows that there is a certain error between the morphology of the post weld pool and the result of the test and the result of the recovery. It is concluded from the numerical simulation that the drop process of the droplet will cause the free surface of the molten pool to be concave; the droplet enters the molten pool and changes the original temperature field and the distribution of the flow field in the molten pool and causes the melting of the molten pool. The free surface of the pool has serious deformation, which makes the free surface of the pool vibration damping with time. Finally, the influence of different welding speed on the three-dimensional surface evolution of the TIG weld pool is analyzed. According to the reflected laser image collected by the acquisition system, the 3D surface of the weld pool of the weld pool at different welding speeds is reconstructed and the results are compared with the experimental results. In order to study the formation mechanism of the rapid TIG welding hump welding track, a mathematical model of the TIG welding hump welding path is established based on FLOW-3D. The temperature field of the fast moving TIG welding hump welding path, the change of the flow field and the free surface are analyzed, and the reasons for the formation of the protruding and lower concave surface of the fast moving TIG weld pool are also analyzed. After the analysis of the distribution of the tracer particles in the molten pool after the solidification of liquid metals, it is found that the pre distributed particles in the surface are located in the hump, partly located in the center of the weld or near the fusion line. Thus, it is concluded that the flow of the liquid gold is not a surface flow under the thermal coupling of TIG welding.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG444.74
[Abstract]:The surface of the molten pool can reflect the formation of the weld, the appearance and the internal quality of the weld. Therefore, a series of research work on the surface of the TIG weld pool is mainly carried out in this paper. A method for the recovery of the three-dimensional surface of the molten pool is proposed. At the same time, the relationship between the surface height of the molten pool and the reflected laser is established, and the three-dimensional morphology of the dissolved pool surface is restored by the obtained reflected laser image and the corresponding geometric parameters. By this method, the three-dimensional surface morphology of the molten pool can be obtained in real time, and the liquid metal flow in the molten pool can be monitored without increasing the cost of the welding production. On the basis of this, it improves the controllability of the welding process, reflects the more abundant three-dimensional information on the surface of the molten pool, and has the theoretical and practical guiding significance for obtaining the beautiful weld seam and improving the welding intelligence. First, the observation test platform for the study of the three-dimensional surface behavior evolution of the TIG weld pool is introduced, and the mirror reflection reflection on the surface of the molten pool is used. The method of using the surface of the molten pool surface to observe its three-dimensional morphology and the restoration algorithm of the three-dimensional surface of the TIG weld pool based on the grid structure laser are proposed. The three-dimensional surface evolution behavior of the fixed point TIG welding pool is observed by this method, and the three-dimensional morphology of the surface of the molten pool is obtained by the recovery algorithm on the surface of the molten pool. The mathematical model of the three-dimensional surface of the fixed point TIG welding pool was established by using the FLOW-3D software, and the numerical analysis was carried out. By comparing the weld pool morphology after the welding, it was found that the experimental results were basically identical with the numerical simulation results. Secondly, the step of welding parameters (current step and speed step), pulse TIG welding, and TIG filler metal welding droplets were three The influence of the surface is explored and the dynamic evolution process of the molten pool surface of TIG welding is analyzed by the combination of simulation and test. The results show that the surface deformation of the molten pool is not very changed from the low current step to the high current; the surface deformation of the molten pool changes obviously from the high current step to the low current, and the step current is between the step current. The larger the difference, the deformation of the surface of the molten pool is more dramatic. From the low speed step to the higher speed, the number of grid laser on the pool is reduced, the surface area of the molten pool decreases first and then increases, and finally tends to be stable. The number of grid laser on the pool increases and the surface area of the molten pool increases from the high speed step to the lower speed. The surface area of the molten pool is increased. By welding the TIG filler wire, the weld pool surface area is increased. The analysis of the surface of the molten pool shows that there is a certain error between the morphology of the post weld pool and the result of the test and the result of the recovery. It is concluded from the numerical simulation that the drop process of the droplet will cause the free surface of the molten pool to be concave; the droplet enters the molten pool and changes the original temperature field and the distribution of the flow field in the molten pool and causes the melting of the molten pool. The free surface of the pool has serious deformation, which makes the free surface of the pool vibration damping with time. Finally, the influence of different welding speed on the three-dimensional surface evolution of the TIG weld pool is analyzed. According to the reflected laser image collected by the acquisition system, the 3D surface of the weld pool of the weld pool at different welding speeds is reconstructed and the results are compared with the experimental results. In order to study the formation mechanism of the rapid TIG welding hump welding track, a mathematical model of the TIG welding hump welding path is established based on FLOW-3D. The temperature field of the fast moving TIG welding hump welding path, the change of the flow field and the free surface are analyzed, and the reasons for the formation of the protruding and lower concave surface of the fast moving TIG weld pool are also analyzed. After the analysis of the distribution of the tracer particles in the molten pool after the solidification of liquid metals, it is found that the pre distributed particles in the surface are located in the hump, partly located in the center of the weld or near the fusion line. Thus, it is concluded that the flow of the liquid gold is not a surface flow under the thermal coupling of TIG welding.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG444.74
【参考文献】
相关期刊论文 前10条
1 何笑英;黄健康;石s，
本文编号：2141848
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