Abstract: This paper focuses on the failure of conventional pressure adjustment in hemming the outer panels of automobile doors and hoods due to factors such as the geometric characteristics of single parts, design styling, and improper adjustment of mold parameters. Through a combination of theoretical analysis and case validation, the study systematically reveals the influence mechanisms and optimization methods for hemming quality issues caused by small R angles on the flanging surface of single parts, the inherent warping characteristics of the clamping flanging process, material flow conflicts due to the convex arc structure of outer panel styling, and improper adjustment of hemming process parameters. The research shows that a small R angle can cause mechanical interference, necessitating the use of a welding pre-hemming process to adjust the R angle to a reasonable range. The inherent warping of the flanging surface in the clamping flanging process can be addressed by optimizing the R angle through welding pre-hemming and improving the stamping flanging process to control the warping amount. For convex arc-shaped surfaces, it is essential to balance the conflict between material accumulation and expansion, and shortening the flanging length can effectively reduce stress concentration. Mold parameter optimization requires collaborative adjustment of parameters such as mold pressure and the position of the bottom mold. Case validation demonstrates that after optimization, the hemming opening dimensions are stably controlled within the enterprise standard range (≤0.3 mm for four doors, ≤0.4 mm for two hoods). The study provides a systematic solution to enhance the failure issues of conventional adjustment in door and hood hemming openings.

Key words: automobile door and hood hemming; opening deviation; pre-hemming optimization; flange height; mold parameters; precision manufacturing

摘要： 文章针对汽车门盖外板压合因单件几何特征、设计造型、模具参数调整不当导致常规 压力调整压合开口失效问题展开研究。通过理论分析与案例验证相结合的方法，系统揭示了 外板单件翻边面 R 角小、夹持翻边工艺固有翻边面翘边特性、外板造型的外凸弧面结构导致的 翻边材料流动矛盾、压合工艺参数调整不当对压合开口质量的影响机理及优化方法。研究表 明：R 角小会引发机械干涉，需采用烧焊预压合工艺调整 R 角至合理范围；夹持翻边工艺固 有翻边面翘边，可通过烧焊预压合工艺调整 R 角及优化冲压翻边工艺控制翘边量；外凸弧面 造型的型面，需平衡聚料与展料矛盾，缩短翻边长度可有效减少应力集中；模具参数优化需 协同调整模具压力、底模位置等参数。案例验证显示，优化后压合开口尺寸稳定控制在企业 标准范围（四门尺寸≤0.3 mm，两盖尺寸≤0.4 mm）内，研究为提升门盖压合开口常规调整失 效问题提供系统的解决方案。

关键词: 汽车门盖压合；开口超差；预压合优化；翻边高度；模具参数；精密制造