角接接头旋转电弧焊接数值模拟研究
发布时间：2018-08-03 19:45
【摘要】：角接接头旋转电弧传感器焊接是焊接行业新技术,其焊接工件冷却后,工件力学性能较好、焊道宽等优点,是国内外焊接行业研究的热点。又因随着建筑、船舶等行业的发展,旋转电弧焊接应用越来越广,普通焊接不能满足工件质量的要求,迫切需要对旋转电弧角接接头焊接特性进行研究。旋转电弧焊接过程中,由于角接接头焊缝自身的特性,影响工件质量的焊接工艺参数因子较多,各因子互相交叉影响,使焊缝成形、熔池形状及焊后工件变形、焊缝缺陷的研究变得复杂,与非旋转电弧焊接相比,焊丝端部具有旋转运动作用,也导致其焊接热源模型更加复杂。而不同焊接因子及焊接热源,会导致焊接温度场、应力场及焊后工件变形的不同。为获得较好焊接质量与控制变形,有必要对其焊接工艺参数进行优化及焊接数值模拟进行研究。本文根据文献分析与前期研究,设旋转电弧为顺时针,旋转半径为3mm,焊炬夹角为45?,以5mm厚碳钢为母材,采用MAG(Metal Active Gas Arc Welding)焊接。首先对焊接工艺参数进行优化研究,结合经验法及参考文献,并考虑各个因子互相作用,在Minitab软件中,设焊接电压、焊接电流分别与焊接速度、旋转频率互相交叉作用,而旋转频率又与焊接速度、干伸长相互交叉影响,采用焊接电压、焊接电流、焊接速度、旋转频率、干伸长及气体流量,6因子3水平的方法,利用田口算法,建立正交模型。根据回归分析法、方差法及平均值法进行分析,得出不同因子之间的关系及好的焊接工艺参数,结果表明,焊缝成形质量分数在11.8分,熔宽误差在1.4附近,余高误差0.31~0.34,会出现畸变现象。针对角接接头旋转电弧焊接热源模型建立,考虑其焊缝特性并引入焊炬夹角,在双椭球热源基础上对其热源模型进行改进,建立新的焊接热源模型,使其能够更加精确描述旋转电弧焊缝形成过程。文中设焊炬夹角为45?,对角焊缝进行分析,提出焊缝参数分布不对称的特点,并求出焊缝热源参数之间的关系,得出宽度比例系数k=1.11,建立焊丝端部运动轨迹,并根据不同旋转频率分析焊丝端部轨迹运动情况。对于焊接工件,其熔池形态尺寸,焊缝成形特点、工件残余应力分布、裂纹大小分布及变形都与工件质量密切相关,为解决焊接中出现的问题,因此需要对旋转电弧角接接头焊接温度场分布,应力场分布进行数值模拟。首先根据文献得出不同温度下的物理材料性能参数及热焓值,其次在Ansys软件中,选用SOLID70单元,进行温度场模拟分析,在应力场数值模拟时,选用SOLID5单元,采用直接耦合法模拟。在焊缝与热影响区采用拖拉及扫略网格划分,在其他地方采用映射网格,采用单元组件及节点组件进行杀死或激活。根据实际焊接情况设置初始边界条件,采用物理化学处理及反演算法,得出改进型旋转电弧双椭质量分数,并对其数值模拟。得出角接接头旋转电弧焊接熔池的形成过程;分析了不同时刻的热循环曲线,动态热源温度场变化,得出靠近上侧板能量较高,易形成咬边,靠近热源中心前端的温度要高于热源中心处及后面部分,上侧板散热梯度要大于下侧板;研究了动态应力场分布,冷却后应力分布,不同路径应力变化及工件变心等问题,得出初始焊接时上侧板变形角度为°3 10′大于下侧板变形的°2 30′;在焊接末端下侧板变形角度为°3 20′,上侧板变形角度为°2 28′比无旋转时变形小;接近热影响区内1.31mm左右,拉应力急剧增大应力变量减小,增量斜率为负;在冷却后,上侧板在X,Y,Z残余应力最大值及畸变程度要小于下侧板,并且下侧板变形更加不规则,出现危险区域频率更高。以上研究成果,可为角接接头旋转电弧焊接工艺参数选择,结构设计、焊接装夹设计、防止工件变形及工程施工提供理论参考,促进了旋转电弧传感器焊接的应用及推广。
[Abstract]:Rotating arc sensor with angular joint is a new technology in welding industry. After the welding workpiece is cooled, the mechanical properties of the workpiece are better, the welding path is wide and so on. It is a hot spot in the welding industry at home and abroad. And because of the development of the building, ship and other industries, the application of rotating arc welding is becoming more and more wide, and the ordinary welding can not meet the requirements of the quality of the workpiece. In the process of rotating arc welding, there are many factors affecting the quality of the workpiece in the process of rotating arc welding, and the factors affecting the quality of the workpiece are many. The factors of each factor cross influence each other, so that the weld formation, the shape of the weld pool and the deformation of the workpiece after welding are complicated, and the research of the weld defect is complicated. Compared with the non rotating arc welding, the end of the wire has a rotating motion, and the welding heat source model is more complex, and the different welding factors and welding heat sources will lead to the welding temperature field, the stress field and the deformation of the post weld workpiece. In this paper, according to the literature analysis and previous research, we set up the rotating arc as clockwise, the rotation radius 3mm, the torch angle of 45?, the 5mm thick carbon steel as the parent material and the MAG (Metal Active Gas Arc Welding) welding. First, the parameters of the welding process are optimized, combined with the experience method and the reference literature, and the examination is taken. Considering the interaction of each factor, in the Minitab software, the welding voltage is set up, the welding current is intersecting with the welding speed and the rotation frequency respectively, and the rotation frequency is intersecting with the welding speed and the dry elongation, and the welding voltage, welding current, welding speed, rotation frequency, dry elongation and gas flow, 6 factor and 3 level are used. The orthogonal model is established by Taguchi algorithm. According to the regression analysis, variance method and mean value method, the relationship between different factors and good welding parameters are obtained. The results show that the weld forming quality score is 11.8, the weld width error is around 1.4, the residual height error is 0.31~0.34, and the distortion will occur. The heat source model of arc welding is set up. Considering its weld characteristics and introducing the torch angle, the heat source model is improved on the base of double ellipsoid heat source, and a new welding heat source model is established to make it more accurate to describe the forming process of the welding seam. The angle of the torch is 45? The angle weld is analyzed and the weld parameters are divided. The relationship between the parameters of the heat source of the welding seam is found and the width ratio coefficient k=1.11 is obtained. The track of the end of the welding wire is established, and the track motion of the wire ends is analyzed according to the different rotation frequency. The shape and size of the weld pool, the shape of the weld, the distribution of the residual stress and the distribution of the crack size and the distribution of the crack size are used for the welding work. The deformation is closely related to the quality of the workpiece. In order to solve the problems in the welding, it is necessary to simulate the distribution of the temperature field and the distribution of the stress field of the rotating arc angle joint. First, the performance parameters and enthalpy values of physical materials at different temperatures are obtained according to the literature. Secondly, in the Ansys software, the SOLID70 unit is selected to carry out the temperature. In the numerical simulation of the stress field, the SOLID5 element is selected and the direct coupling method is used in the numerical simulation of the stress field. The mapped mesh is used in the weld and the heat affected zone, the mapping grid is used in other places, the unit components and the node components are used to kill or activate. The original boundary conditions are set up according to the actual welding condition and the object is used. In the process of chemical treatment and inversion, the mass fraction of the improved rotating arc double ellipsoid is obtained, and its numerical simulation is carried out. The forming process of the welding pool of the rotating arc welding of the angle joint is obtained. The thermal cycle curve and the change of the temperature field of the dynamic heat source are analyzed at different time. It is concluded that the energy of the plate near the upper side is high, and the edge is easily formed, close to the front end of the heat source center. The temperature of the upper side plate is higher than the center and the rear part of the heat source. The thermal gradient of the upper plate is greater than that of the lower side plate. The distribution of the dynamic stress field, the stress distribution after cooling, the change of the stress of the path and the change of the workpiece are studied. The deformation angle of the upper side plate is 310 'greater than that of the lower side plate deformation at the initial welding, and it is under the welding end. The deformation angle of the side plate is 320 ', and the deformation angle of the upper side is less than that of no rotation. Near the 1.31mm in the heat affected zone, the tensile stress increases sharply and the increment slope is negative. After cooling, the maximum and distortion of the upper side plate in X, Y, Z is less than that of the lower side plate, and the deformation of the lower side plate is less than that of the lower side. The above research results can provide theoretical reference for the selection of technological parameters, structure design, welding clamp design, prevention of workpiece deformation and engineering construction, and promote the application and popularization of the welding of rotating arc sensor.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG457.11
本文编号：2162814
[Abstract]:Rotating arc sensor with angular joint is a new technology in welding industry. After the welding workpiece is cooled, the mechanical properties of the workpiece are better, the welding path is wide and so on. It is a hot spot in the welding industry at home and abroad. And because of the development of the building, ship and other industries, the application of rotating arc welding is becoming more and more wide, and the ordinary welding can not meet the requirements of the quality of the workpiece. In the process of rotating arc welding, there are many factors affecting the quality of the workpiece in the process of rotating arc welding, and the factors affecting the quality of the workpiece are many. The factors of each factor cross influence each other, so that the weld formation, the shape of the weld pool and the deformation of the workpiece after welding are complicated, and the research of the weld defect is complicated. Compared with the non rotating arc welding, the end of the wire has a rotating motion, and the welding heat source model is more complex, and the different welding factors and welding heat sources will lead to the welding temperature field, the stress field and the deformation of the post weld workpiece. In this paper, according to the literature analysis and previous research, we set up the rotating arc as clockwise, the rotation radius 3mm, the torch angle of 45?, the 5mm thick carbon steel as the parent material and the MAG (Metal Active Gas Arc Welding) welding. First, the parameters of the welding process are optimized, combined with the experience method and the reference literature, and the examination is taken. Considering the interaction of each factor, in the Minitab software, the welding voltage is set up, the welding current is intersecting with the welding speed and the rotation frequency respectively, and the rotation frequency is intersecting with the welding speed and the dry elongation, and the welding voltage, welding current, welding speed, rotation frequency, dry elongation and gas flow, 6 factor and 3 level are used. The orthogonal model is established by Taguchi algorithm. According to the regression analysis, variance method and mean value method, the relationship between different factors and good welding parameters are obtained. The results show that the weld forming quality score is 11.8, the weld width error is around 1.4, the residual height error is 0.31~0.34, and the distortion will occur. The heat source model of arc welding is set up. Considering its weld characteristics and introducing the torch angle, the heat source model is improved on the base of double ellipsoid heat source, and a new welding heat source model is established to make it more accurate to describe the forming process of the welding seam. The angle of the torch is 45? The angle weld is analyzed and the weld parameters are divided. The relationship between the parameters of the heat source of the welding seam is found and the width ratio coefficient k=1.11 is obtained. The track of the end of the welding wire is established, and the track motion of the wire ends is analyzed according to the different rotation frequency. The shape and size of the weld pool, the shape of the weld, the distribution of the residual stress and the distribution of the crack size and the distribution of the crack size are used for the welding work. The deformation is closely related to the quality of the workpiece. In order to solve the problems in the welding, it is necessary to simulate the distribution of the temperature field and the distribution of the stress field of the rotating arc angle joint. First, the performance parameters and enthalpy values of physical materials at different temperatures are obtained according to the literature. Secondly, in the Ansys software, the SOLID70 unit is selected to carry out the temperature. In the numerical simulation of the stress field, the SOLID5 element is selected and the direct coupling method is used in the numerical simulation of the stress field. The mapped mesh is used in the weld and the heat affected zone, the mapping grid is used in other places, the unit components and the node components are used to kill or activate. The original boundary conditions are set up according to the actual welding condition and the object is used. In the process of chemical treatment and inversion, the mass fraction of the improved rotating arc double ellipsoid is obtained, and its numerical simulation is carried out. The forming process of the welding pool of the rotating arc welding of the angle joint is obtained. The thermal cycle curve and the change of the temperature field of the dynamic heat source are analyzed at different time. It is concluded that the energy of the plate near the upper side is high, and the edge is easily formed, close to the front end of the heat source center. The temperature of the upper side plate is higher than the center and the rear part of the heat source. The thermal gradient of the upper plate is greater than that of the lower side plate. The distribution of the dynamic stress field, the stress distribution after cooling, the change of the stress of the path and the change of the workpiece are studied. The deformation angle of the upper side plate is 310 'greater than that of the lower side plate deformation at the initial welding, and it is under the welding end. The deformation angle of the side plate is 320 ', and the deformation angle of the upper side is less than that of no rotation. Near the 1.31mm in the heat affected zone, the tensile stress increases sharply and the increment slope is negative. After cooling, the maximum and distortion of the upper side plate in X, Y, Z is less than that of the lower side plate, and the deformation of the lower side plate is less than that of the lower side. The above research results can provide theoretical reference for the selection of technological parameters, structure design, welding clamp design, prevention of workpiece deformation and engineering construction, and promote the application and popularization of the welding of rotating arc sensor.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG457.11
【参考文献】
相关期刊论文 前2条
1 张利国;姬书得;方洪渊;刘雪松;;分段焊的焊接顺序对T形接头残余应力场的影响[J];焊接学报;2006年12期
2 熊震宇;董洁;谢雨田;蒋海侠;;焊接过程的有限元模拟[J];南昌航空大学学报(自然科学版);2008年02期
相关硕士学位论文 前1条
1 刘翠霞;旋转电弧自保护焊焊缝成形及自动跟踪的研究[D];华南理工大学;2011年
，本文编号：2162814
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