高强镀锌板拉延摩擦多尺度多因素耦合建模与协同控制

As to the complexity and variety of high strength galvanized sheets' drawing friction used in automobiles, on the basis of micro-tribological, lubrication mechanics, rheological, plastic mechanics and material science, considering the high strength galvanized sheets' microstructure, lubricants rheological, friction heat effect, deformation inhomogeneity, interface characteristics and coupling of blank and mould, the tribological properties and formability and its relationship was studied. The friction and coating interaction mechanism was analyzed. The failure mechanism of zinc layer and interface and the micro-mechanism of friction was discussed. The friction-induced evolution of surface microstructure and surface morphology was explored. Plastic fluid dynamic pressure lubrication model and nonlinear friction model of high strength galvanized sheet's drawing was established based on multi-scale and multi-factor coupling. It provides the basic theories and method to describe the high strength galvanized sheet's friction properties accurately. On this basis of present work, the forming limit diagram of high strength galvanized sheet's drawing was established and frictional couple's coupling concurrency controlling method was present. The results will lay the foundation for high strength galvanized sheet's drawing-forming process and die design as well as accurate simulation, at the same time, provide the technical support to the active control of drawing part's surface quality and die life so as to realize high strength galvanized sheet's precise controlled forming.

针对汽车用高强镀锌板拉延摩擦的复杂多变性，基于微观摩擦学、润滑力学、流变学、塑性力学和材料学，考虑高强镀锌板的微观结构、润滑剂流变性、摩擦热效应、变形不均匀性、表界面特性以及板材与模具的耦合作用，研究高强镀锌板的摩擦学特性、拉延成形性及其内在联系。分析锌层与摩擦的相互作用机制；探明锌层及界面失效机制及摩擦力形成的微观机制；探索摩擦诱发高强镀锌板表面微观结构和表面形貌的演变机理和表征方法；建立高强镀锌板拉延成形多尺度、多因素耦合的塑性流体动压润滑模型和非线性摩擦模型，为准确描述高强镀锌板拉延的摩擦特性提供基础理论与方法；在此基础上，建立高强镀锌板拉延成形极限图并提出摩擦副的耦合协同控制方法。研究结果将为高强镀锌板拉延成形工艺模具设计及精确仿真奠定基础，同时为拉延件表面质量和模具寿命的主动控制提供技术支撑，实现高强镀锌板精密可控成形。

随着汽车工业在国内外的快速发展，越来越多的消费者对汽车的耐久性和耐蚀性要求不断提高。镀锌板因为其非常良好的成形性能、焊接性能、涂装性能和耐蚀性能而广泛应用到车身制造上。.板料成形过程中必然伴随着工件和模具间的剧烈摩擦，摩擦非材料的固有特性，与表面形貌、接触方式、润滑方式、冲压工艺条件等多种复杂因素有关，是一个典型的多因素、跨尺度、非线性复杂问题。无论是实验研究还是理论分析，研究难度大，研究结果的一致性差甚至有完全相反的结论。. 镀锌板可以分为镀层、界面和基体三个部分，组织结构比普通钢板复杂，其摩擦特性和成形性不同于一般钢板。针对汽车用高强镀锌板拉延摩擦的复杂多变性，基于微观摩擦学、润滑力学、塑性力学和材料学，考虑高强镀锌板的微观结构、摩擦热效应、变形不均匀性、表界面特性以及板材与模具的耦合作用，采用平板滑动实验、杯突实验、摩擦磨损实验，应用SEM、XRD、三维形貌仪等现代分析测试手段，研究高强镀锌板的摩擦学特性、拉延成形性及其内在联系，分析了锌层与摩擦的相互作用机制，探明了锌层及界面失效机制及摩擦力形成的微观机制。镀锌板冲压成形时，锌层中会出现裂纹、断裂、粉化与剥落等失效现象，塑性变形的诱发作用和接触摩擦的双重影响导致镀锌板表面形貌在冲压成形过程中随着时空变化。采用统计的方法表征了冲杯实验过程不同变形区的形貌模型，基于分形理论，建立了考虑板料的力学性能、表面形貌和接触压力这三种因素的接触模型和摩擦模型。在此基础上，建立了高强镀锌板拉延成形极限图，提出了摩擦副的耦合协同控制方法。采用SEM、EBSD、TEM、单向拉伸试验机等设备和仪器，探讨了合金元素和轧制技术参数对汽车用低碳钢板的微观组织和力学性能的影响，揭示了合金元素的作用机理和最优的轧制技术参数范围。. 研究结果为高强镀锌板拉延成形工艺模具设计及精确仿真奠定基础，同时为拉延件表面质量和模具寿命的主动控制提供技术支撑，实现高强镀锌板精密可控成形。