窄间隙GMAW焊枪设计及立焊工艺特性研究

发布时间：2018-05-03 12:06

本文选题：窄间隙焊 + 摆动电弧　；参考：《哈尔滨工业大学》2014年硕士论文

【摘要】：近几年，随着压力容器、核电、海洋工程及油气管道行业装备的日趋大型化重型化，厚板厚管焊接结构的应用越来越广泛，窄间隙全位置焊接的需求大幅增加。而立焊作为全位置焊接的重要组成部分，受重力的影响，如果工艺参数选择不当，容易出现熔池下淌，焊缝成形不良的问题，焊接难度较大。为了解决窄间隙焊接时的侧壁熔合问题，保证立焊接头的焊接质量与生产效率，设计了一个小型的摆动电弧窄间隙焊炬，探索了窄间隙立焊时工艺参数对焊接稳定性及焊缝成形的影响规律，确定了立向上焊和立向下焊的最佳工艺参数范围，并在此基础上完成了厚板单道多层焊试验，得到了无宏观缺陷的立焊接头，利用高速摄像技术对比分析了摆动电弧立向上焊和立向下焊的熔滴过渡形式及电弧、熔池行为，为以后实现厚壁管道的摆动电弧窄间隙全位置焊接做好准备。（1）首先设计并优化了焊炬的电路系统、水冷系统和气保护系统，经实验验证，焊炬性能稳定，能够适应长时间焊接工作。（2）研究了摆动电弧窄间隙立向上焊和立向下焊时保护气流量、焊接电流、焊接速度、摆动角度、摆动频率及侧壁停留时间对焊缝成形的影响，初步分析了不同工艺参数下的立向上和立向下焊焊缝成形特点及产生原因，进行了25mm厚Q235钢的立向上及立向下单道多层焊试验，得到了无宏观缺陷的立焊焊接接头。（3）利用高速摄像技术观察了摆动电弧窄间隙GMAW的电弧行为及熔滴过渡，研究了窄间隙平焊时摆动对电弧形态及熔滴过渡的影响，发现摆动时由于受到离心力的作用，电弧和熔滴都偏离焊丝轴线，且熔滴尺寸减小，过渡频率增大；对比分析了立向上焊和立向下焊时工艺参数对电弧形态及熔滴过渡方式的影响规律，给出了两种工艺下焊缝成形出现明显差异的原因。（4）从力的角度揭示了立向上焊和立向下焊焊接工艺和焊缝成形存在较大差异的本质原因，结合不同焊枪倾角下采集到的熔滴过渡图像，分析了立向上焊和立向下焊时熔滴与熔池的力学行为。
[Abstract]:In recent years, as the equipment of pressure vessel, nuclear power, marine engineering and oil and gas pipeline industry is becoming more and more heavy, the application of thick plate and thick pipe welding structure is becoming more and more extensive, and the demand for narrow gap all position welding is greatly increased. As an important part of all position welding, vertical welding is affected by gravity, if the selection of process parameters is improper. It is easy to weld down the weld pool and cause poor weld formation.
In order to solve the problem of side wall fusion in narrow gap welding and ensure the welding quality and production efficiency of vertical welding joint, a small arc narrow gap welding torch is designed. The influence of process parameters on welding stability and weld formation is explored, and the best process parameters for vertical and vertical welding are determined. On this basis, a single channel multi layer welding test of thick plate has been completed, and a vertical welding joint without macroscopic defects is obtained. By using high speed camera technology, the form of droplet transition and arc, and the behavior of the molten pool are compared and analyzed. The behavior of the molten pool is good for the future realization of the full position welding of the narrow gap between the wobble arc and the thick wall pipe. Prepare.
(1) first, the circuit system, water cooling system and gas protection system of the welding torch are designed and optimized. The experimental results show that the torch has stable performance and is suitable for long time welding work.
(2) the effects of protecting gas flow, welding current, welding speed, swing angle, swing frequency and the residence time of side wall on the weld forming are studied, and the forming characteristics and causes of vertical and vertical downward welding weld under different process parameters are preliminarily analyzed. The 25mm thick Q235 steel is carried out. Vertical and vertical welding tests were carried out and vertical weld joints without macroscopic defects were obtained.
(3) the arc behavior and droplet transition of the narrow gap GMAW of the oscillating arc are observed by high speed camera technology. The influence of the swing on the arc shape and droplet transition in narrow gap welding is studied. It is found that the arc and droplets all deviate from the wire axis due to the centrifugal force, and the droplet size decreases and the transition frequency increases. The influence of process parameters on the shape of arc and the mode of droplet transition is analyzed, and the reasons for the obvious difference in the weld formation under the two processes are given.
(4) from the angle of force, the essential reasons for the large difference between the vertical and vertical welding process and the weld formation are revealed, and the mechanical behavior of the droplets and the molten pool is analyzed by combining the droplet transition images collected under the different angle of the welding torch.

【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TG434.5;TG44

【参考文献】