超高强钢厚板结构件MIG焊温度场应力场数值模拟及试验研究

发布时间：2018-03-17 16:42

  本文选题：数值模拟　切入点：多层多道焊　出处：《南京理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：重型车辆塔体由多块20-60mm厚高强钢板以及塔体头拼焊而成,属于典型的箱型结构,采用多层多道PMIG焊接工艺,依据工装夹具定位固定,塔体制造要求严格的尺寸精度,需严格控制焊接变形。本文总结了前人对焊接数值模拟的研究,成功进行车体炮塔顶板和侧板多层多道焊连接数值模拟,研究焊接过程中顶板的受热变形规律以及不同焊道顺序、不同约束条件下侧板连接发生焊接变形的规律,并进行炮塔焊接工艺试验,验证焊接温度、应力场模拟计算结果。研究了塔体PMIG自动焊接热源模型,对热源双椭球模型进行了二次开发,通过校核熔融效果优化热源函数能量分布系数。顶板焊接开始后,熔池中心区域峰值温度为2256℃,熔池呈“梨形”空间分布,随着热源前移,熔池温度逐渐降低,等温线轮廓呈现以焊接方向为长轴的近椭圆形状,应力应变云图显示主要应力分布区为起弧点、焊道中部和收弧点。研究了侧板的焊接应力场分布规律,研究三种焊道顺序、三种约束条件下侧板焊接的受热及变形规律,Ⅲ方案焊道顺序下板件受热均匀,焊后变形量小,残余应力分布最优,焊缝体的最高应力值为896.5MPa,起、收弧端应力值在239～418MPa之间；综合焊接变形和焊后残余应力分布,V方案约束条件最优,变形集中在焊缝上,焊缝体及近焊缝区的形变量在0.228～0.452mm之间,焊缝残余应力值在376.0～484.9MPa之间,残余应力的分布区域在夹具释放后明显缩小,应力场分布得到优化。进行了炮塔焊接工艺试验：选测点的热循环曲线变化趋势与计算模型相一致,峰值温度、温度升高速度和温度冷却速度误差百分比均符合精度要求；最终获得的熔池形态中,第二道次的熔宽、熔深与模型中W2熔池区域基本一致；盲孔法测得1、2号特征点应力值分别为169.4MPa、195.8MPa与模拟结果相近,板件的焊后变形趋势与模拟结果相同。综上所述,本文计算结果精度符合要求,模型验证正确,本文的模型可以为焊接工艺方案制定提供参考。
[Abstract]:The tower body of heavy vehicle is composed of several thick steel plates of 20-60 mm thick and high strength, and the head of tower body is welded together. It belongs to the typical box type structure. It adopts multi-layer and multi-pass PMIG welding technology, and is fixed according to the fixture, and has strict dimensional precision required for the manufacture of tower body. It is necessary to strictly control welding deformation. In this paper, the previous researches on welding numerical simulation are summarized, and the numerical simulation of multi-layer and multi-pass welding connection of car body turret roof and side plate is successfully carried out. The rules of thermal deformation of roof in welding process and the rules of welding deformation of side plate connection under different welding pass sequence and different restraint conditions are studied. The welding process test of turret is carried out to verify the welding temperature. The heat source model of PMIG automatic welding of tower body was studied. The double ellipsoid model of heat source was redeveloped. The energy distribution coefficient of heat source function was optimized by checking the melting effect. The peak temperature in the central region of the molten pool is 2256 鈩，

本文编号：1625606