拼焊板盒形件拉深成形理论与控制技术的研究

The main problem of tailor welded blank deep drawing is the flange wrinkling and sidewall (box-shaped, etc.) wrinkling and rupture, so the possibility of real-time control for sheet metal wrinkling and rupture is the key of the deep drawing process. Due to the influence of weld-line movement, different material thickness and material property, weld properties, heat affected zone and the forming process, tailor welded blank forming process is more complex compared with single sheet metal forming process. At present, tailor welded blank deep drawing part is needed more and more,but there are also some problems in the production. so it is necessary to study tailored welded blanks box-shaped deep drawing process theory and control technology. The best prediction of blank holder force is created by forming limit diagram and the movement model of weld line, Combined with mechanics and initial macroscopic physical quantities (drawing force, drawing stroke, the blank holder force, etc.), is monitored by the control system, the mateial property of tailor welded blanks is identified by the module of BP neural network, the identified material property is used to predict the required best blank holder force in deep drawing. The optimal blank holder force is controled by the control system to get the best quality of tailor welded blanks box-shaped part. At present, the real-time control technology research in the tailor welded blanks deep drawing process so far has not been reported at home or abroad.It is significant for the application of tailor welded blanks in the industrial production.

拼焊板拉深成形最突出的问题是法兰和侧壁（对于盒形件等）起皱及侧壁破裂，能否对起皱和破裂进行实时控制是其能否顺利成形的关键。与单板成形相比，由于料厚比、材质、焊缝性能、热影响区以及成形过程中焊缝移动的影响，使拼焊板成形过程更为复杂。而当前汽车工业对拼焊板拉深件的需求日益增加，而且生产过程中依然存在很多亟待解决的问题。针对这一现状，拟开展拼焊板盒形件拉深成形理论及控制技术研究。通过解析法建立综合考虑起皱和破裂的拼焊板盒形件拉深成形极限图和焊缝移动模型，建立完整的可预测拼焊板拉深成形最佳压边力的力学模型。结合力学模型和拉深初期宏观物理量（拉深力、拉深行程、压边力等）的监测，实现对最佳压边力的实时控制，从而实现对成形过程中起皱、破裂及焊缝移动的实时控制，可获得高精度的拉深件，对推动拼焊板冲压件在汽车车身制造业中更为广泛的应用将有重要的意义。

拼焊板盒形件拉深成形最突出的问题是在拉深过程中法兰和侧壁起皱、侧壁破裂和焊缝移动。与整板盒形件拉深成形相比，拼焊板盒形件的成形受到料厚比、摩擦系数、焊缝性能、热影响区以及成形过程中焊缝移动等因素的影响。为解决上述问题，本项目对拼焊板盒形件拉深成形理论及控制技术展开了研究。通过解析法建立了拼焊板盒形件拉深成形过程应力解析模型，同时提出了焊缝移动量计算模型；针对拼焊板盒形件拉深成形，综合考虑破裂、起皱、焊缝移动等问题，利用有限元方法研究了压边力、料厚比、摩擦系数等参数对其成形的影响。通过“小尺寸型”拼焊板试样单向拉伸、混合法则和纳米压痕等技术，分别建立了拼焊板焊缝及热影响区金属的平均和非平均弹塑性力学性能测定模型，建立了拼焊板盒形件法兰起皱、侧壁破裂等缺陷的成形极限图和压边力预测的力学模型；分析了拼焊板方盒形件拉深成形过程中的主要影响因素，引入人工神经网络模型，建立了拼焊板方盒形件拉深成形过程中较优的压边力神经网络预测模型。基于正交试验设计和有限元数值模拟构建了神经网络预测模型所需的训练样本，从而实现了压边力控制规律的准确预测；改进现有实验装置，更新了实时信号采集系统，构建了拼焊板盒形件拉深成形过程实时控制系统，实现了对拼焊板盒形件拉深成形过程实时监测和控制。. 本项研究具有以下三个方面的意义：一是建立了拼焊板盒形件拉深成形理论及控制技术，具有重要的理论意义；二是将人工神经网络模型应用于压边力的预测，对工程实际中所涉及的关键技术问题提出先进的解决方案，具有重要的实际应用价值。三是建立了拼焊板盒形件拉深成形实时控制系统，对生产实际起到了重要的指导作用。