锻模热负荷参数的工程计算方法

On Computing Damage to Hot Forging Die Due to Thermal Loading

对锻模热负荷参数的表征与计算进行了研究 ,选用热强度系数描述锻模材料的抗热损伤能力 ,回火系数描述锻模材料的热软化程度 ,热载系数描述锻模材料的热疲劳程度。应用传热学和热弹塑性理论 ,推导出了上述热负荷参数的计算公式。并针对锻模的实际使用和损伤情况 ,利用频谱分析方法 ,确立了锻模热负荷参数的工程计算方法。应用该方法 ,分析研究了几种典型锻模的热负荷状况 ,计算结果与有限元分析结果相一致 ,并与统计规律相吻合 。

Hot forging die cost is about 30% of hot forging cost in China, about twice as high as that prevailing in developed countries. Prolonging life of hot forging die and reducing hot forging cost require computation of thermal loading damage to hot forging die. In section 1 we discuss separately three thermal loading parameters P T, P σ , and Q of typical hot forging die. Eqs. (1), (2) and (3) are the formulas for computing P T, P σ , and Q respectively. P T and P σ are also known as abrasion index and thermal fatigue index respectively. In section 2, we discuss how to make use of statistical data to compute the two above mentioned indexes. In section 3 we summarize in Tables 1 and 2 the results of analysis of three typical hot forging dies. The results show that our method is quite promising for prolonging life of hot forging die and reducing hot forging cost. The results also show preliminarily that damage due to thermal fatigue is primarily caused by low cycle fatigue, i.e., fatigue caused by low frequency components of big temperature rise and fall of frequent temperature cycles.