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摘要汽车零部件制造中，很多都是用螺母与钢板的电阻焊连接，尤其以在螺母上先预制凸点，再与钢板进行凸焊连接为多。本文以某汽车零部件生产制造中采用M8螺母与2mm厚的镀锌钢板连接为研究对象，对其凸焊工艺进行试验和优化。在实际工况条件下通过正交试验，在上下电极保持平行的前提下获得最佳焊接规范为焊接电流26KA，焊接时间15cyc，供给压强0.45MPa，获得了焊点破坏性试验三个凸点都被拉破，焊点截面熔核满足使用要求的结果。33991
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力学性能检测采用顶出力试验，螺母顶出力为13KN，大于规范要求的4KN。金相试验结果表明，凸点熔核组织为柱状晶形态，接头组织为铁素体加珠光体,熔核与热影响区晶粒较母材粗大。
关键词 镀锌钢板 螺母凸焊 参数优化 破坏试验 金相组织
毕业论文设计说明书外文摘要
Title Optimization of the parameters for the welding of automobile parts
Abstract
In the manufacture of automobile parts, resistance welding of nuts and steel plates is largely adopted，especially the way to make salient points on the nuts first and then connect the steel plates with project-welding.this paper researches the connection of M8 nut and 2mm thick galvanized steel sheet,make experiments and optimize its project-welding technology.Optimal welding specifications were obtained through orthogonal experiments under actual working condition,in this case:the main welding current is 26KA,electrode pressure is 0.45MPa and the main welding time is 15 cycles,the premise is that the electrode must be kept.The result that three salient points can be pulled broken in destructive test and the nucleation of the solder joints section meets the requirements is acquired.
Mechanical performance test using the top strength test,the top strength is 13KN,exceeds the specification 4KN.Metallographic test results show that the micro structure of the salient point is columnar crystal,the joint microstructure is ferrite and pearlite,the grain size of the nugget and heat affected zone is thicker then that in the parent material.
Keywords Galvanized steel Nut project-welding Optimize the welding parameters Damage experiment Metallographic structure
目 次
1 绪论3
1.1 课题背景3
1.2 电阻点、凸焊原理3
1.3 镀锌钢板在汽车工业中的应用3
1.4 镀锌钢板电阻点、凸焊的研究概况4
1.5 螺母凸焊的国内外研究现状6
2 试验材料及设备方法8
2.1 试验材料8
2.2 试验设备及仪器9
2.2.1 焊接设备9
2.2.2 压力试验机 10
2.2.3 熔深检测及金相观察 11
2.3 试验方法 11
3 螺母凸焊工艺试验及结果 13
3.1 电极平行度调节 13
3.2 前期试验 14
3.2.1 生产现场螺母凸焊工艺试验 14
3.2.2 焊点破坏试验观察 15
3.2.3 焊点截面熔核观察 16
3.3 正交试验 18
4 焊点的力学性能及接头的微观组织 21
4.1 焊点的力学性能 21
4.2 凸焊接头的微观组织 22
5 凸焊缺陷分析 23
5.1 虚焊 23
5.2 焊核直径过小 23
5.3 气孔 23