Reheating Furnace Analysis and Optimization for Hot Stamping Automotive Parts

热冲压是加拿大汽车制造能力中越来越重要的一部分。在这个过程中，高 将称为“坯件”的硼钢板加热到约950 ℃并在该温度下保持长达5分钟， 形成奥氏体。坯件通常浸涂有铝硅层，该铝硅层在金属层内与钢熔合。 炉，提供短期的保护，防止结垢和长期的耐腐蚀性。然后，热坯料是 转移到模具中，在模具中同时冲压成形并淬火，从而形成均匀的马氏体 具有很高的硬度和屈服强度。热冲压生产具有上级碰撞的汽车部件 与其他制造技术相比， 制造成本，以及生产更安全，更轻，更省油的汽车。 最近的热冲压创新主要集中在改进模具技术上，但高度控制毛坯 加热对于获得碰撞性能所需的均匀硬度和拉伸强度也是必不可少的，并且 所需的保护涂层厚度，以保持零件的可焊性，用于随后的组装。不均匀加热 导致有缺陷的零件，这些零件必须通过昂贵的工艺（如激光切割）进行校正，或者简单地 丢弃。 本文的研究重点是建立辊底式和低矮型间歇式炉的传热模型 目前由加拿大首屈一指的一级汽车零部件供应商Cosma International使用。这些模型将用于 用于设计优化和在线控制加热炉的操作参数，从而提高工艺效率 （每分钟的零件数）和零件质量。热传递模型还允许Cosma修改炉参数， 考虑到工艺变量、毛坯几何形状和毛坯材料的变化。这反过来又将提供更大的 工艺灵活性和显著提高生产率。最后，从长远来看，传热模型将指导 Cosma收购和开发新的加热技术。

Hot stamping is an increasingly important part of Canada's automotive manufacturing capacity. In this procedure, high boron steel sheets, called "blanks", are heated to approximately 950C and held at that temperature for up to 5 minutes to form austenite. The blanks are usually dip-coated with an aluminum-silicon layer that fuses to the steel within the furnace, providing short-term protection against scaling and long term corrosion-resistance. The hot blank is then transferred to a die in which it is simultaneously stamped into shape and quenched, thereby forming a uniformlymartensitic part of very high hardness and yield strength. Hot stamping produces automotive parts having superior crash performance with less material and in less time compared to other fabrication techniques, dramatically reducing manufacturing costs, and producing safer, as well as lighter, more fuel-efficient cars. Recent innovations in hot stamping have focused mainly on improving die technology, but highly-controlled blank heating is also essential to achieve the homogeneous hardness and tensile strength needed for crash performance, and the desired protective coating thickness to preserve part weldability for subsequent assembly. Inhomogeneous heating results in defective parts, which must either be corrected through expensive processes like laser-cutting or are simply discarded. The proposed research is focused on developing heat transfer models of roller hearth and low-profile batch furnaces presently used by Cosma International, Canada's premier Tier 1 automotive parts supplier. The models will then be used for design optimization and online control of the furnace operating parameters, thereby improving process efficiency (parts per minute) and part quality. The heat transfer models will also permit Cosma to modify the furnace parameter to account for changes to process variables, blank geometries and blank materials. This, in turn, will provide greater process flexibility and significantly improve productivity. Finally, in the longer term, the heat transfer models will guide Cosma's acquisition and development of new heating technologies.