超窄间隙焊接工艺稳定性影响因素的研究

发布时间：2018-08-27 16:31

【摘要】：焊剂片约束电弧超窄间隙焊接方法经过不断地发展已经取得许多阶段性成果。目前该技术主要研究的问题是:(1)如何实现焊剂片及焊剂片链的自动化生产;(2)如何稳定地将焊剂片链输送到坡口中完成稳定的焊接过程,获得性能良好的焊接接头。本文在总结以往焊剂带(焊剂片链)制作工艺和适用性能优缺点的基础上,重新设计了焊剂片的结构并通过压片法制备出所设计的焊剂片。为了解决单个的焊剂片容易绕着玻璃纤维线旋转的问题,本文提出了玻璃纤维网式焊剂片链,这种结构的焊剂片链不仅保留了玻璃纤维线式焊剂片链的优点而且具有很好的弹性。当焊剂片链被输送到坡口中时,焊剂片链能够紧贴坡口两侧壁,从而保证焊后坡口两侧壁和根部熔合良好。为了编织本文设计的玻璃纤维网,作者制作了一套简单的玻璃纤维网编织机;同时对玻璃纤维网粘结剂的配比进行了探究,试验发现环氧树脂与稀释剂的配比为1:2时,涂敷粘结剂后玻璃纤维网不仅具有较好的弹性,而且玻璃纤维网对折时不易断裂。为了实现自动化超窄间隙焊接,作者设计了一套四自由度超窄间隙焊接实验装置。此套装置由送置焊剂片链超窄间隙焊接专用焊枪、焊接工装夹具、焊接实验装置行走机构组成。送置焊剂片链超窄间隙焊接专用焊枪不仅能够实现焊剂片链的自动输送,而且焊枪的送丝导电部分采用了一体化设计,大大减少了焊枪零部件的个数,便于焊枪的装配和拆卸。焊接工装夹具由四条方形钢连接而成,利用加力螺栓和两个定位螺栓对焊接试样进行装夹定位。焊接实验装置行走机构具有四个自由度,能够沿着X轴、Y轴、Z轴移动和绕着Z轴旋转。最后,利用作者制作的超窄间隙焊接实验装置进行工艺试验;本文分别从下降外特性电源、焊丝偏移量、坡口宽度变化量三个方面探究其对超窄间隙焊接工艺稳定性的影响。在相同焊接工艺参数下,通过对比下降外特性电源和平特性电源模式下焊接试样的焊缝横截面形貌和焊接过程波形的变化,发现下降外特性电源能够增加电弧的稳定性,对超窄间隙焊接具有更好的适应性。以往的焊接工艺试验已经证实焊丝与焊剂片之间的距离对约束电弧、焊缝成形起着至关重要的作用,而且两者之间的距离为0.35~0.5mm时焊缝成形质量最好。本文通过玻璃纤维网纵向线的直径控制焊丝与焊剂片之间的距离,当焊丝偏离坡口中心线时,焊丝与玻璃纤维网的纵向线之间将会产生力的作用,从而造成焊丝端头产生微量的变形,保证焊丝端头与焊剂片之间有足够的距离,从而保证坡口侧壁和根部熔合。实际工业生产中同一条焊道上的坡口宽度会产生一定量的变化,本文通过一定焊接工艺参数下焊接V形焊道试样模拟这一现象。试验发现:随着坡口宽度的增加,熔滴过渡频率减小,焊接电流和电弧电压的波动性增大。
[Abstract]:Flux-confined arc ultra-narrow gap welding method has been continuously developed and achieved a lot of achievements. At present, the main problems of this technology are as follows: (1) how to realize the automatic production of flux sheet and flux chain; (2) how to transport the flux chain steadily to the groove to complete the stable welding process and obtain the welding joint with good performance. On the basis of summarizing the advantages and disadvantages of the manufacturing technology and the applicable properties of the flux strip (flux chain), the structure of the flux sheet was redesigned and the designed flux sheet was prepared by pressing the flux strip. In order to solve the problem that a single flux sheet rotates easily around the glass fiber line, a glass fiber mesh flux chain is proposed in this paper. This kind of flux chain not only retains the advantages of glass fiber wire flux chain, but also has good elasticity. When the flux chain is transported to the groove, the flux chain can close to the two sides of the groove, so as to ensure a good fusion between the two sides of the groove and the root after welding. In order to weave the glass fiber mesh designed in this paper, the author made a simple glass fiber mesh knitting machine, and studied the proportion of the glass fiber mesh binder, and found that the ratio of epoxy resin and diluent was 1:2. After coated with binder, glass fiber mesh not only has good elasticity, but also is not easy to break in half fold. In order to realize automatic ultra narrow gap welding, the author designed a four-degree of freedom ultra narrow gap welding experimental device. The device is composed of welding torch, welding fixture and walking mechanism of welding experiment device. The welding torch for ultra-narrow gap welding of flux chain can not only realize the automatic conveying of flux chain, but also adopt the integrated design of wire feeding conductive part of welding torch, which greatly reduces the number of welding torch parts and facilitates the assembly and disassembly of welding torch. The welding fixture is made of four square steel. The welding specimen is clamped by adding bolt and two positioning bolts. The walking mechanism of the welding experimental device has four degrees of freedom and can move and rotate around the Z axis along the X axis and Y axis. Finally, the process test is carried out by using the ultra-narrow gap welding experimental device made by the author, and the influence of this device on the stability of the ultra-narrow gap welding process is explored from three aspects: the power supply with descending external characteristics, the wire offset and the change of the groove width, respectively. Under the same welding process parameters, by comparing the shape of weld cross section and the variation of welding process waveform of welding sample in the mode of decreasing external characteristic power supply and characteristic power supply, it is found that the drop external characteristic power supply can increase the stability of arc. It has better adaptability to ultra narrow gap welding. Previous welding process tests have proved that the distance between wire and flux sheet plays an important role in arc restraint and weld formation, and the quality of weld formation is the best when the distance between the two is 0.35~0.5mm. In this paper, the distance between the wire and the flux sheet is controlled by the diameter of the longitudinal line of the glass fiber mesh. When the wire deviates from the central line of the groove, the force between the wire and the longitudinal line of the glass fiber mesh will be produced. Thus the wire end is deformed and the distance between the end of the wire and the flux sheet is enough to ensure the fusion of the side wall and the root of the groove. The width of the groove on the same welding pass will change in a certain amount in the actual industrial production. This paper simulates this phenomenon through the welding V-shaped welding specimen under certain welding process parameters. It is found that the droplet transfer frequency decreases and the welding current and arc voltage fluctuate with the increase of the groove width.
【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】：TG44

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