中厚板Al-Mg铝合金双机器人双面双弧焊接工艺研究

发布时间：2018-01-20 02:27

本文关键词： 双面双弧 Al-Mg铝合金温度场模拟焊接变形双面TIG填丝交流波形　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：为实现中厚板Al-Mg铝合金机器人自动化高效焊接,提高焊接质量与焊接效率,本文以15mm厚Al-Mg铝合金板对接接头为研究对象,确定了以机器人双面双TIG焊接打底,双TIG填丝焊填充的焊接方法,基于机器人双面双弧焊接工作站,实现双机器人协调运动、同步行走、双侧成形的自动化焊接。开展了机器人双面双TIG自熔焊和双面TIG填丝焊接工艺试验,掌握了焊接速度、线能量等工艺参数对焊缝成形和缺陷形成的影响规律。自熔打底焊线能量在9KJ/cm到12.1KJ/cm范围内能够形成良好的焊接接头,焊缝表面宽度随焊接线能量的增加而增大。重点研究了双面T1G填丝焊接过程中,送丝角度和钨丝间距对焊缝成形的影响,试验表明:送丝角度为45°时,钨丝间距的最佳参数为8mm,焊丝熔滴能够被直接送入焊缝熔池,有效减少熔合线气孔的产生。重点对双面双弧焊接和传统TIG焊接进行了对比,从焊后变形量、焊接温度场分布、显微组织和力学性能四个方面进行研究。利用百分表对两种焊接接头的焊后变形量进行测量,从测量结果得出,双面双弧打底焊后最大高度变化量为0.185mm,填丝焊后最大角变形为0.69°,仅为传统TIG焊后变形量的24.1%。基于ANSYS软件为平台,采用高斯函数分布的热源模型,对DSAW和传统TIG焊打底接温度场进行数值模拟,得到了不同时刻焊接温度场分布。研究表明:双面双弧焊接温度场具有温度梯度小、等温线范围大、最高温度高等特点,其厚度方向上的温度场分布十分均匀,可以说明DSAW对于减小角变形具有优势,与试验测量结果吻合。DSAW打底焊焊缝组织以α(Al)+β(Mg_2Al_3)为主,晶粒细小均匀;传统TIG焊打底焊缝组织含有白色片状(Al、Si)二元脆性相,对接头力学性能有较大影响。DSAW填丝焊焊缝组织与自熔焊组织类似,主要为α(Al)+(βAl8Mg5),但单弧填丝焊缝存在一种破碎状缺陷组织。双弧接头的平均抗拉强度为237MPa,为母材的86.2%,延伸率为母材的81%,均高于单弧焊接接头。探究交流波形正负半波比例对接头气孔率的影响,当正负半波比例在1.09-1.40范围内增加时,相当于一个交流周期内直流正接部分的电流幅值增大,焊接热输入增加,有利于提高气泡上浮速度,促使气泡逸出,降低气孔倾向。
[Abstract]:In order to realize automatic and high efficiency welding of Al-Mg aluminum alloy plate, and improve welding quality and efficiency, this paper takes 15mm thick Al-Mg aluminum alloy plate butt joint as the research object. The welding method based on robot double side double TIG welding and double TIG filler wire welding is determined. Based on the robot double side double arc welding workstation, the coordinated movement and synchronous walking of the two robots are realized. Automatic welding of bilateral forming. The experiments of robot double-sided double-#en0# self-melting welding and double-side TIG filling wire welding were carried out, and the welding speed was mastered. The effect of process parameters such as line energy on weld formation and defect formation. The welding wire energy of self-melting bottom welding can form good welding joint in the range of 9KJ / cm to 12.1 KJ / cm. The width of weld surface increases with the increase of welding line energy. The influence of wire feeding angle and tungsten wire spacing on weld formation in the process of two-sided T1G wire filling welding is studied. The test results show that the wire feeding angle is 45 掳. The optimum parameter of tungsten wire spacing is 8mm, the droplet of welding wire can be directly fed into the weld pool, which can effectively reduce the formation of weld wire blowhole. The emphasis is on the comparison between double-side double-arc welding and traditional TIG welding. The deformation of two kinds of welded joints was measured from four aspects: post-weld deformation, temperature distribution, microstructure and mechanical properties. The results were obtained from the measurement results. The maximum height change after double arc bottom welding is 0.185 mm, and the maximum angle deformation is 0.69 掳after wire filling welding. It is only 24.1% of the traditional TIG welding deformation. Based on the ANSYS software, the heat source model of Gao Si function distribution is adopted. The numerical simulation of the temperature field of DSAW and traditional TIG welding is carried out, and the distribution of temperature field at different times is obtained. The results show that the temperature field of double arc welding has a small temperature gradient and a wide range of isotherms. The distribution of the temperature field in the thickness direction is very uniform due to the high maximum temperature, which indicates that DSAW has an advantage in reducing angular deformation. The results are in agreement with the experimental results. The microstructure of the weld seam of DSAW bottom welding is 伪 -Al) 尾 -Mg2Al3), and the grain size is fine and uniform. The microstructure of the traditional TIG welding bottom weld contains white flake Al Si) binary brittle phase, which has a great influence on the mechanical properties of the joints. The microstructure of the weld is similar to that of the self-fusion welding. The average tensile strength of the double arc joint is 237 MPA, which is 86.2% of the base metal. The ratio of positive and negative half waves of AC waveform on porosity of joints was investigated when the ratio of positive and negative half waves increased in the range of 1.09-1.40. The increase of current amplitude and welding heat input in the direct current of the direct current in an AC cycle is beneficial to increase the bubble floating speed, promote the bubble to escape and reduce the porosity tendency.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG409

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