多硬度结构淬硬钢模具的铣削稳定性预测研究

Hardened steel molds with multi-hardness structures can meet the requirements of uninformed stress in different zone of mold cavity during the stamping process, has great significantly to improve mold service life. Molds with multi-hardness structure have been used in auto mould instead of uniform hardness molds gradually and become one of the trends in this field.. According to the scientific research of milling stability during multi-hardness mould milling process, a new method named equivalent flow stress for the sandwich structure zones was promoted for the first time in this project, then establish dynamic milling force model which can be used to predict the dynamic cutting force of the multi-hardness hardened steel. Theoretical research based on the empirical mode decomposition method and random decrement technique was carried out following operational modal analysis, kinetic milling force model of the hardened steel molds with multi-hardness structure can be deduced. Verifications for the dynamic milling force and kinetic milling force model can be compared between numerical simulation and experimental results, the new methods of the milling stability prediction of hardened steel molds with multi- hardness structure would be received in the end..By using dynamometer, SEM, XRD, EDS, roughness measurement method to measure milling force , tool wear , surface integrity. Surface quality, machining efficiency and tool life under the premise of chatter-free milling were selected as optimization objectives, can be optimized by change milling process parameters. This project aim to provide technical support for the high-performance milling hardened steel molds with multi-hardness structures.

多硬度结构淬硬钢模具可满足冲压过程中型腔各部位应力不均匀的要求，能显著提高模具使用寿命，已逐步取代整体结构模具成为该领域重要发展趋势之一。. 针对多硬度结构淬硬钢模具的铣削稳定性科学难题，首次提出了三明治夹层结构区的等效流动应力建模方法，建立多硬度淬硬钢动态铣削力模型；开展基于经验模态分解法-随机减量法的铣削系统工作模态分析方法理论研究，建立多硬度结构淬硬钢模具的铣削动力学模型；以多硬度结构淬硬模具钢为研究对象，数值模拟结合试验研究验证动态铣削力和铣削动力学模型，形成多硬度结构淬硬钢模具铣削稳定性预测新方法。综合采用测力仪、SEM、XRD、EDS、粗糙度仪等进行铣削力、刀具磨损、已加工表面质量的测试分析，在实现无颤振铣削加工的前提下，以表面质量、加工效率和刀具寿命为优化目标，进行铣削加工工艺参数优化，为实现多硬度结构的淬硬钢模具高性能铣削加工提供技术支撑。

通过焊接工艺拼接制造的三明治结构多硬度淬硬钢广泛运用于航空、航天及汽车模具等不同领域，能够满足日益复杂型腔不同部位受力不同的要求。由于材料特性存在差异，多硬度结构淬硬钢模具精密铣削加工时容易发生铣削颤振，加剧刀具磨损、降低表面质量和加工效率。本项目制备了多硬度结构淬硬Cr12MoV模具钢试件，结合有限元分析、动力学建模、模态参数识别、稳定性分析与试验研究等方法，对运行模态分析方法以及多硬度淬硬钢铣削过程中的铣削力、铣削振动以及稳定性预测进行了研究。通过纳米压入技术测定了Cr12MoV焊接过渡区组织和力学性能，建立了铣削过程有限元模型及铣削力预测模型；开展了基于互谱函数及互相关函数的铣削系统工作模态分析方法的理论和实验研究；建立了三明治结构淬硬钢的铣削动力学模型，数值模拟结合试验研究验证了模型的正确性，实现了多硬度结构淬硬钢铣削稳定性预测分析。综合采用Kistler测力仪、SEM、XRD、EDS、粗糙度仪等进行铣削力、铣削振动、已加工表面质量的测试分析，在实现无颤振铣削加工的前提下，以表面质量为优化目标，优化了铣削加工工艺参数，为实现三明治结构淬硬钢的高效铣削加工提供技术支撑，具有较为重要的科学意义和工程应用价值。