车身电泳膜厚的精确计算及工艺孔的影响研究

发布时间：2018-08-14 18:55

【摘要】：电泳涂膜具有很高的防腐能力,是车身防腐的基础。由于车身内腔结构的复杂性,相对于外表面而言,内腔表面电泳涂膜上漆能力较弱,而车身内腔电泳涂膜厚度不足将直接影响整车的防腐性能。工程上一般是通过试制样车、剖解后发现车身电泳风险区域。这种“试制—纠错”的模式成本高、周期长,并且一旦涉及到设计更改,工程师一般是凭借经验,难以保证完全解决生锈问题。近年来电泳仿真技术的发展使得在设计阶段预测内腔电泳膜厚数值成为可能,但目前的工作都局限于应用仿真工具进行简单分析和验证,没有形成规律性的结论来指导工程师进行结构设计和更改。本论文针对车身内腔电泳膜厚不足导致生锈,而传统试错方法耗费大量成本、电泳工艺开孔缺乏科学依据等问题,采用先整体后局部的分析方法,实现了车身电泳膜厚的精确计算,在此基础上,提出了一种能实现车身电泳工艺孔正向设计的新方法—区域分析法,应用该方法研究了工艺孔对内腔膜厚的影响。首先,获取电泳过程中的电场信息,搭建电泳电化学仿真环境,并通过电泳涂料沉积参数标定基础试验和仿真,反求得到涂料的基本沉积参数,为电泳仿真分析奠定了基础。其次,建立了车身电泳数值分析模型,以车身整体的电泳宏观分析结果作为输入,进行车身电泳关键区域的电泳微观分析,实现了电泳膜厚的高效精确计算,将仿真分析膜厚与实车测量膜厚进行对比,验证了先整体后局部分析方法的可靠性,在此基础上,基于数值分析获得了内腔电泳成膜过程。然后,构建了大梁区域简化结构的电泳电化学全耦合仿真模型。以工艺孔形状、大小为变量,以电化学分析为手段进行研究发现:开孔形状对膜厚影响较小、而开孔面积影响较大,并得到了膜厚衰变的数值规律,导出了内腔电泳膜厚的安全系数。通过对双孔叠加效果的分析,进一步推导出孔间距的安全系数。最后,将量化的研究结果应用于某车大梁区域的结构更改,成功解决了该区域内腔生锈问题,验证了应用区域分析方法的有效性。
[Abstract]:Electrophoretic coating has high anticorrosion ability and is the base of body anticorrosion. Because of the complexity of the internal cavity structure, the ability of electrophoretic coating is weak compared with the external surface, and the lack of thickness of the internal cavity electrophoresis coating will directly affect the anticorrosion performance of the whole vehicle. Engineering is generally through the trial production of the car, after dissecting the body electrophoretic risk area. This "trial-error correction" model has high cost, long cycle, and when it comes to design changes, engineers generally rely on experience to ensure that rust problems can not be completely solved. In recent years, the development of electrophoretic simulation technology makes it possible to predict the thickness of electrophoretic film in the design stage, but the current work is limited to simple analysis and verification using simulation tools. There are no regular conclusions to guide engineers in structural design and modification. In order to solve the problems of rusting caused by insufficient thickness of electrophoretic film in car body, traditional methods of trial and error cost a lot of cost and lack of scientific basis for the opening of electrophoretic process, the analysis method of whole and then local is adopted in this paper. The accurate calculation of body electrophoretic film thickness is realized. On the basis of this, a new method, region analysis method, is proposed, which can realize the forward design of body electrophoretic process holes. The effect of process holes on the thickness of inner cavity film is studied by using this method. Firstly, the electric field information in the electrophoretic process is obtained, and the electrophoretic electrochemical simulation environment is set up, and the basic deposition parameters of the coating are obtained by the basic experiment and simulation of the electrophoretic coating deposition parameters, which lays a foundation for the electrophoresis simulation analysis. Secondly, a numerical model of body electrophoretic analysis is established. The electrophoretic microanalysis of key areas of body electrophoresis is carried out with the result of whole electrophoretic macroscopic analysis as input, and the effective and accurate calculation of electrophoretic film thickness is realized. The simulation analysis of film thickness is compared with the actual measurement of film thickness, and the reliability of the method is verified. On the basis of this, the process of electrophoretic film formation is obtained based on the numerical analysis. Then, the electrophoretic electrochemistry full coupling simulation model of the simplified structure in beam region is constructed. With the shape and size of the process holes as variables, electrochemical analysis was used to study the film thickness. It was found that the open hole shape had little effect on the film thickness, but the open hole area had a great effect on the film thickness, and the numerical law of the film thickness decay was obtained. The safety factor of electrophoretic film thickness was derived. By analyzing the superposition effect of two holes, the safety factor of hole spacing is further deduced. Finally, the quantitative research results are applied to the structural change of a vehicle beam area, which successfully solves the problem of internal cavity rust in the region, and verifies the effectiveness of the applied area analysis method.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U466

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