气体保护三丝间接电弧特性及其厚壁窄间隙焊接工艺研究

发布时间：2018-06-10 02:35

本文选题：三丝 + 间接电弧　；参考：《大连理工大学》2017年博士论文

【摘要】：现代工业的发展对高效焊接技术的需求愈来愈迫切,尤其是大型结构件产品的制造对高熔敷率焊接技术的需求越来越多。但是采用传统电弧焊接时,如果增加焊接电流来提高熔敷率,母材热输入势必增加,容易导致焊缝性能下降等问题。为了增加熔敷率的同时减少热输入,双丝间接电弧焊是一种很好的方法。在双丝间接电弧焊的基础上,本文引入第三根焊丝,首次提出了三丝间接电弧焊,通过第三根焊丝产生的磁场控制电弧形态,解决了大电流时双丝间接电弧形态发散导致热输入过小的问题。对三丝间接电弧焊的稳定性、电弧形态、熔滴过渡、电弧特性、熔敷率等进行了研究和分析。首次利用三丝间接电弧,开发了窄间隙气体保护三丝间接电弧焊工艺,并对该工艺侧壁熔合和多层焊层间熔合进行了重点探讨。本文的主要研究内容如下:(1)研究了气体保护三丝间接电弧特性。三丝间接电弧的主丝电流大于边丝电流,能够对电弧形态起到约束作用,由电弧挺度原理,三丝间接电弧受到主丝磁场作用,整体沿着主丝延长线方向,避免了电弧形态发散。另外,三丝间接电弧焊有多种焊丝分布方式,其影响磁场分布状态,因此可以利用焊丝分布对三丝间接电弧形态进行调控,即对间接电弧热量分布进行调控。(2)研究了气体保护三丝间接电弧熔滴过渡特性。三根焊丝之间的相互电磁力对熔滴过渡产生了较大的影响,由于边丝电磁力对主丝熔滴过渡起促进作用,试验条件下,主丝一直为射流过度,并沿着主丝延长线。由于主丝电磁力对边丝的排斥作用,使得边丝熔滴过渡被排斥离开主丝。(3)研究了气体保护三丝间接电弧焊熔敷率特性。由于电源的连接方式发生改变,与同样有两个焊接电源的传统双丝焊相比,三丝间接电弧焊时,用于熔化焊丝的电弧热量多,而用于熔化母材的电弧热量少。如试验条件下,三丝间接电弧的母材熔化效率2.09%～12.43%,焊丝熔化效率61.09%～90.31%;传统双丝电弧的母材熔化效率22.15%～27.44%,焊丝熔化效率37.69%～46.84%。根据实际试验和查阅相关资料,与传统双丝焊相比,如480 A时,传统双丝焊的熔敷率为8.04 Kg/h,而三丝间接电弧焊的熔敷率为25.5 Kg/h,三丝间接电弧焊提高熔敷率200%以上。与双丝间接电弧焊相比,由于可用参数范围提高,三丝间接电弧提高了熔敷率可用上限。(4)开发了窄间隙气体保护三丝间接电弧焊工艺。利用焊丝分布对三丝间接电弧和熔滴过渡进行调控,使得电弧热量集中到母材侧壁上,实现了窄间隙三丝间接电弧焊侧壁熔合。当主丝为竖直向下时,熔池积累在主丝之下,电弧的位置不能进一步降低,电弧的热量无法作用到焊缝根部,焊缝根部未能熔合。而当主丝倾斜后,熔池积累在主丝之后,焊枪高度可以进一步降低,使得电弧热量能够到达焊缝根部,焊缝根部熔合。(5)提出了后置钨极电弧的方法,改善了窄间隙气体保护三丝间接电弧焊焊缝成形。由于三丝间接电弧主丝的熔敷金属在焊缝中央大量积累,没有其它辅助的情况下,窄间隙三丝间接电弧焊的焊缝表面呈凸起状。窄间隙多层焊接时,凸起状焊缝成形使得焊枪高度无法降低,电弧热量无法作用到焊缝根部,容易造成焊缝根部未熔合和层间熔合困难。针对此问题,根据钨极电弧压力使焊缝表面下凹的现象,提出了在三丝间接电弧后添加钨极电弧的方法,改善了焊缝成形。后置钨极电弧后,窄间隙三丝间接电弧焊的焊缝表面变为凹状,且随着钨极电流的增大,钨极电弧压力增加,焊缝表面下凹程度明显增加。
[Abstract]:The demand for high efficiency welding technology is becoming more and more urgent in the development of modern industry, especially for the manufacture of large structure parts. The demand for high melting rate welding technology is more and more. However, when the traditional arc welding is used, if the welding current is added to improve the melting rate, the heat input of the base material will be increased and the weld performance will be reduced easily. In order to increase the melting rate and reduce the heat input at the same time, double wire indirect arc welding is a good method. On the basis of double wire indirect arc welding, third wires are introduced in this paper. Three wire indirect arc welding is proposed for the first time. The electric arc state is controlled by the magnetic field produced by third wires, and the shape hair of double wire indirect arc is solved when the current is large. The problem of heat input is too small. The stability of the three wire indirect arc welding, the shape of the arc, the droplet transition, the characteristics of the arc and the melting rate are studied and analyzed. The indirect arc welding process of the narrow gap gas protection three wire is developed for the first time using three wire indirect arc, and the fusion of the side wall and the interlayer fusion of the multi layer welding process is also carried out. The main contents of this paper are as follows: (1) the characteristics of indirect arc of three wire in gas protection are studied. The main wire current of three wire indirect arc is larger than the edge wire current, it can play a restraining effect on the shape of the arc. The principle of arc stiffness, the indirect arc of the three wire is affected by the magnetic field of the main wire, the whole direction of the wire is extended along the main wire, and the arc is avoided. Form divergence. In addition, three wire indirect arc welding has a variety of wire distribution mode, which affects the distribution of magnetic field. Therefore, the distribution of welding wire can be used to regulate the form of indirect arc of three wires, that is, the indirect arc heat distribution is regulated. (2) the characteristics of the droplet transition between the three wire arc welding arc welding and the interaction between the three wires are studied. The electromagnetic force has a great influence on the droplet transition, because the edge wire electromagnetic force plays an important role in the transition of the main wire droplet transition. Under the test conditions, the main wire has been overflowing the jet and extending the wire along the main wire. Due to the repellent effect of the main wire electromagnetic force to the edge wire, the side wire is excluded from the main wire. (3) the gas protection three wire is studied. Compared with the traditional double wire welding with the same two welding power, three wire indirect arc welding has more arc heat than the traditional double wire welding with the same two welding power, and the arc heat used to melt the material is less than that of the three wire indirect arc welding. For example, the melting efficiency of the three wire indirect arc is 2.09% ~ 12.43. The melting efficiency of welding wire is 61.09% ~ 90.31%, the melting efficiency of the traditional double wire arc is 22.15% ~ 27.44%, the melting efficiency of welding wire is 37.69% ~ 46.84%., according to the actual test and the related data, compared with the traditional double wire welding, such as 480 A, the penetration rate of the traditional double wire welding is 8.04 Kg/h, and the deposition rate of the three wire indirect arc welding is 25.5 Kg/h, three wire. Indirect arc welding increases the deposition rate of more than 200%. Compared with double wire indirect arc welding, the three wire indirect arc improves the application rate of the welding rate, as compared with the double wire indirect arc welding. (4) the indirect arc welding process of the narrow gap gas protection three wire is developed. The arc heat can be controlled by the distribution of wire on the indirect arc and droplet transition of the three wire. When the main wire is vertical downward, the weld pool accumulates under the main wire, the position of the arc can not be further reduced, the heat of the arc can not be applied to the weld root, and the weld root is not fused. When the main wire is inclined, the weld pool is accumulated after the main wire and the welding gun is high after the main wire is inclined. The degree can be further reduced, so that the arc heat can reach the weld root and the weld root fusion. (5) the method of the rear tungsten arc is put forward to improve the formation of the three wire indirect arc welding seam forming in the narrow gap gas protection. Because the deposited metal of the three wire indirect arc main wire accumulates in the center of the weld, there is no other auxiliary condition. The weld surface of the three wire indirect arc welding has a convex shape. When the narrow gap is multi-layer welding, the height of the welding gun can not be reduced and the heat of the arc can not be used to the root of the weld. It is easy to cause the weld root to be not fused and the interlayer fusion is difficult. The method of adding tungsten pole arc after three wire indirect arc is proposed to improve the weld formation. After the rear tungsten arc, the weld surface of the narrow gap three wire indirect arc welding becomes concave, and with the increase of the tungsten current, the pressure of the tungsten arc increases and the concave degree of the weld surface increases obviously.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TG444.72

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