【作者】 刘丽；

【导师】 庄蔚敏；

【作者基本信息】 吉林大学 ， 车辆工程（专业学位）， 2019， 硕士

【摘要】 汽车企业在进行新车型白车身试制时除了会引入新的工艺方法,更多的体现在引进新材料。目前高强钢板以其明显的成本优势和优良的成型工艺性成为汽车厂商目前最为青睐的新型材料。更多的采用高强钢板使三层板搭接头点焊比以往比例更高,可达全车焊点的1/2。与二层板点焊相较而言,三层板搭接头实际点焊生产中更容易出现熔核过小、熔核偏移、烧穿、飞溅等焊接质量问题。保证三层钢板焊点强度质量对提高车身质量很重要。实际试制车身焊接时采用料片试焊的方式进行焊接参数的调试。由于全车三层板搭接由于材料不同、料厚不同,往往有30种到50种组合,每种组合都需要制备10组以上的料片用于进行点焊参数调试。整个车身需要做300到500组三层钢板点焊试验对于材料及工时的浪费可以想见。论文针对这个问题,结合试验设计、有限元分析进行车身点焊优化方法研究。本论文针对某车型侧围总成拼焊时的一种三层钢板(含两种高强钢板)搭接组合的点焊参数优化过程开展研究工作:第一章节除了对研究现状进行介绍,同时对研究工作进行了总体安排;第二章对于三层钢板点焊的可能影响因素进行深入的分析,并根据其可控性和影响程度对这些影响因素进行筛选,从中确定焊接电流、焊接时间、电极压力作为后续试验因素;第三章根据减少试验次数的原则,对试验采用均匀设计的方法,减少试验点,并对试验结果进行回归分析,得到点焊参数的回归方程。第四章建立有限元模型,并对某车型侧围三层钢板搭接组合进行仿真。仿真结果与第三章实操试验熔核尺寸数据比对,验证模型有效。就此可以得出点焊参数优化的系统方法。本研究结合均匀设计分析与有限元分析,简化电阻点焊工艺参数设定过程,有效降低设定系数所耗费的工时及材料用量。关于焊接参数优化试论文针对上述工程技术难题,结合企业实际生产及工艺状况,通过试验分析与理论研究的方法对三层钢板电阻点焊过程中三层板搭接头焊接质量主要影响因素开展研究,结合试验结果建立三层钢板电阻点焊有限元模型并进行模拟仿真和试验验证,从而揭示三层钢板熔核质量控制要点。结合实际生产,对现有工艺提出优化以改善三层钢板焊点熔核偏移、飞溅、表面质量等问题,提高车身焊点质量,简化焊接参数制定过程。论文结合企业生产工艺与工程技术问题,完成对现有白车身电阻点焊参数的设计与优化。研究结果表明,可采用结合均匀设计分析与有限元分析的方法简化电阻点焊工艺参数设定方法,减少三层钢板焊点缺陷,对于提高车身焊点质量和表面质量效果显著。更多还原

【Abstract】 In addition to introducing new process methods,automobile enterprises will introduce new materials in the trial production of new body in white.At present,high-strength steel plate has become the most popular new material for automobile manufacturers because of its obvious cost advantage and excellent molding technology.More high-strength steel plates are used to make the spot welding ratio of three-layer plate lap joint higher than before,up to 1 / 2 of the whole vehicle.Compared with the two-layer spot welding,the three-layer lap joint is more prone to welding quality problems such as too small nugget,nugget offset,burn through,spatter and so on.It is very important to ensure the strength and quality of the welding spot of the three-layer steel plate to improve the body quality.In the actual trial production of body welding,the test welding method of sheet metal is used to adjust the welding parameters.Due to different materials and material thicknesses,there are usually 30 to 50 combinations for three-layer plate lapping of the whole vehicle.Each combination needs to prepare more than 10 groups of sheets for spot welding parameter debugging.The whole body needs to do 300 to 500 groups of three-layer steel plate spot welding test,which can be imagined for the waste of materials and working hours.Aiming at this problem,this paper studies the optimization method of body spot welding combining with experimental design and finite element analysis.In this paper,the optimization process of spot welding parameters of a three-layer steel plate(including two kinds of high-strength steel plates)is studiedThe first chapter not only introduces the current situation of the research,but also makes the overall arrangement of the research work;In the second chapter,the possible influencing factors of spot welding of three-layer steel plate are analyzed,and these influencing factors are selected according to their controllability and influence degree,from which the welding current,welding time and electrode pressure are determined as the following test factors;In the third chapter,according to the principle of reducing the number of tests,uniform design method is used to reduce the number of test points,and regression analysis is carried out on the test results to get the regression equation of spot welding parameters.In the fourth chapter,the finite element model is established,and the lap joint of three-layer steel plate on the side wall of a car is simulated.The simulation results are compared with the nugget size data of the third chapter,and the model is verified to be effective.The systematic method of spot welding parameter optimization can be obtained.In this study,uniform design analysis and finite element analysis are combined to simplify the process of setting resistance spot welding process parameters and effectively reduce the time and material consumption of setting coefficient.On the optimization of welding parametersIn view of the above engineering and technical problems,combined with the actual production and technological conditions of the enterprise,the paper studies the main factors influencing the welding quality of the three-layer steel plate lap joint in the process of resistance spot welding by means of experimental analysis and theoretical research,establishes the three-layer steel plate resistance spot welding finite element model and carries out simulation and test verification based on the test results,so as to reveal the three-layer steel plate Key points of nugget quality control.Combined with the actual production,the existing process is optimized to improve the nugget offset,spatter,surface quality and other problems of the three-layer steel plate welding spot,improve the quality of the body welding spot,and simplify the process of welding parameter formulation.In this paper,the design and optimization of resistance spot welding parameters of BIW are completed based on the production process and engineering technology.The research results show that the method of combining uniform design analysis and finite element analysis can be used to simplify the process parameter setting method of resistance spot welding,reduce the defects of three-layer steel plate solder joints,and improve the quality of body solder joints and surface quality significantly.更多还原