装载机覆盖件热冲压成形传热与淬火冷却速度研究

Study on heat transmission and quench cooling speed for hot stamping and forming of loader panels

回弹和变形是影响高强度装载机覆盖件冲压成形形状精度的主要因素,通过22MnB5合金板热冲压成形实验,考察了热冲压成形的传热特征,推导出的热冲压成形传热数学模型的基本方程,提出热冲压成形模具冷却系统设计相关技术问题.研究表明,当冷却速度达到或超过临界冷却速度,才能使奥氏体直接转变为均匀马氏体;在模具结构、冷却系统、冷却介质等因素确定的情况下,冷却速度只与板材自身条件有关,可以通过控制最佳水流速度实现对最佳冷却速度的控制,达到减少和消除热冲压成形中变形和回弹等缺陷,提高装载机覆盖件热冲压成形质量.

The rebounding and distortion largely impact the forming precision on strength loader panels. Through the experiments on the 22MnB5 alloy sheets, the heat transmission property is initially investiga- ted into hot stamping and forming. Upon reduction of the basic equation of mathematical model, relevant technological problems are speculated for cooling system design on heat stamping and forming molds. Subsequently, it is indicated that, only when the cooling speed approaches or exceeds the critical cooling speed, the austenitic can be directly transformed to the martensite. If the mold structure, cooling system and cooling media remain unchangeable, the cooling speed is only related to the sheets. By controlling the optimal waterflow speed so as to obtain the optimal cooling speed, the defects of distortion and rebounding can be reduced even eliminated to improve the stamping and forming quality of loader panels.