基于数值模拟和3D打印的热冲压模具随形水道设计制造研究

针对传统热冲压模具深孔对钻冷却系统冷却不均的现象,基于热冲压过程的多场耦合传热理论,提出热冲压模具随形冷却系统设计方法。利用Star-ccm+软件对热冲压冷却淬火过程进行热流固耦合模拟。以自主研发的彩虹电动汽车B-柱模具镶块为研究对象,对传统深孔对钻和新提出多种随形设计方案进行了冷却模拟分析。根据模拟结果,比较分析了不同冷却方案的冷却效果,并提出B柱模具镶块纵向随形冷却水道的优化方案,分析了优化前、后模面温度场的变化。提出运用覆膜砂3D打印造型结合传统铸造工艺的方法,制造具有随形冷却水道的热冲压模具。通过对比五种方案发现,采用纵向随形设计的热冲压模具,与冷却最差的平行随形设计相比,模面最大温度降低47.4%,模面平均温度降低40.9%,模面温度均匀性提高1.8%。根据纵向随形水道设计流程,将水道形状和位置参数R、H、r作为优化参数,模面温度场作为优化目标,对纵向随形水道进行优化,结果显示,优化后模面最大温度下降了49.8%,模面平均温度下降了46.8%,模面温度标准偏差下降了67.5%,模面温度均匀性提高了1.9%。因此,采用随形冷却的热冲压模具,有效地提高了生产加工效率和使用寿命,改善了热冲压件的平均强度和组织与力学性能的均匀性。

Investigation of Design and Manufacture in Hot Stamping Tools with Conformal Cooling Channels Based on Simulation and 3D-printing Technology

To against the uneven cooling of traditional hot stamping tool with opposite deep-hole drilling cooling system, a new design method of hot stamping tool with conformal cooling channels is put forward, which is based on multi-field couplings in heat transfer theory and simulated by Star-ccm+. By taking the insert of a B-pillar tool on the self-developed rainbow electric car as the research object and comparing the cooling effects of traditional hole drilling and some newly proposed cooling designs, a new optimization strategy for B-pillar tool insert with longitudinal conformal cooling channel arrangement is applied and the temperature distribution of work surface before and after optimization has been analyzed. Hot stamping tool with conformal cooling channels is fabricated by means of combining 3D printing technique of precoated sand with traditional sand casting. This hot stamping tool with optimized longitudinal conformal design overcome the cooling limitations of parallel conformal designs, such as maximum temperature of work surface decreases by 47.4%, average temperature decreases by 40.9% and temperature uniformity improves by 1.8%. According to the design process of longitudinal conformal cooling channel, the parameters of channel shape and location such asR, H, rare set as optimization variables and the surface temperature field will serve as the optimization object. The optimization result shows that the maximum temperature of work surface decreases by 49.8%, and the average temperature decreases by 46.8%, and the temperature standard deviation decreases by 67.5%, while the temperature uniformity increases by 1.9%. It is found that this hot stamping tool with conformal cooling channels upgrades production efficiency and prolongs service life-span, furthermore, the uniformity of mechanical properties of hot stamping parts is improved.