变厚度钢板成形特性

One of the new lightweight methods is to stamp the body parts with tailor rolled blank (TRB) according to the actual loads. While the systematic research on the formability of TRB has not been carried out. It delays the extensive applications of this new type blank. Our group has carried out the research on the rolling and formability of TRB for several years. Based on these works, the universal formability (including fracture resistance, fitting behavior and shape fixability ) of TRB will be systematically investigated. The project will focus on the effects of the specific characteristic such as geometry, mechanical property, microstructure of TRB. The new evaluation method for the formability of TRB will be promoted. Based on the stamping experiments with typical models or actual parts, the inhomogeneous deformation behavior and the metal flow will be investigated. Thus the new theory about metal flow control and the optimization method during the whole process will be proposed. The innovative: 1) The precise constitutive model of TRB with the performance difference in a sheet will be established. 2) The new idea of controlling blank holder forces with lattice pieces will be proposed. The corresponding mechanical devices and controlling rules will be developed. 3) The optimization method during the whole process of design, rolling, stamping and service will be proposed and the specialized software will be developed. With the help of the project, the rational evaluation of formability of TRB and the optimization of service behaviors and stamping processes are achieved. It will benefit the applications of TRB and automobile lightening.

根据载荷分布选用变厚度钢板制造车身冲压件，是实现汽车轻量化的新方法。但变厚度钢板成形特性尚未得到系统研究，阻碍了其广泛应用。本申请团队多年从事变厚度板轧制和成形性能研究，在此基础上拟对变厚度钢板综合成形性能（含抗破裂性、贴模性和定形性等）进行系统研究，特别关注其几何、力学、组织差异化对成形性能的影响，探讨评价变厚度板成形性能新方法。同时通过典型零件成形试验，研究变厚度板非均匀变形现象，分析金属流动规律，提出变厚度板金属流动控制理论和全流程优化分析方法。项目创新点：1)建立考虑同体性能差异化特征的变厚度板高精度本构模型；2)针对变厚度板不均匀变形提出点阵随形压边力控制技术思路，开发相应装置和控制策略；3)提出变截面零件设计、轧制、冲压成形、服役承载全流程优化方法，并开发专用工具。通过上述研究，建立变厚度钢板成形性能评价标准，优化冲压工艺，改进零件服役性能，以促进变厚度板在汽车轻量化中的应用。

汽车轻量化一直是汽车行业孜孜以求的目标，采用变厚度钢板（轧制差厚板）制备符合载荷分布的车身零部件，是实现车身轻量化的重要途径。变厚度钢板在合资车型中已有应用，但自主车型中的应用尚不多见，其主要障碍在于对变厚度钢板成形性能的研究不够充分。. 本项目针对变厚度钢板的成形特性，开展了间接成形性能、抗破裂性、贴模性、定形性的研究，建立了高精度本构模型和成形性能评价方法。同时，研究了变厚度钢板冲压成形时的金属流动，开发了点阵随形压边装置并进行了验证。在此基础上，利用现有商业软件开发了全流程优化分析工具。与企业合作，试制了变厚度前纵梁内板、变厚度吸能盒、变厚度热冲压B柱和前防撞梁等实际车身零件。本项目按计划完成了相关研究内容，并实现了预期的研究目标。其主要成果体现在4个方面：1）建立了变厚度钢板的高精度本构模型。可以考虑加工硬化和退火工艺因素、各向异性因素、非线性卸载现象、包辛格效应等，实现对变厚度钢板冲压过程的高精度模拟；2）提出了变厚度钢板力学行为的直接表征方法。设计等屈服概率拉伸试样，通过单向拉伸试验可以获得不同厚度区域材料的真应力-真应变曲线；3）验证了点阵随形压边装置的可行性。制备了带有点阵随形压边装置的盒形件冲压模具，实现对变厚度钢板厚度的自适应压边，并较好地控制金属流动；4）开发了变厚度钢板全流程优化分析工具。实现对零件设计-冲压成形-服役承载过程的全流程优化，以合理确定冲压工艺和最终零件厚度分布。基于这些研究工作，试制了实际的车身零件，取得了良好的效果。本项目的研究成果对促进自主车型应用变厚度钢板实现轻量化提供了有力的支撑。