34CrNiMo6钢三拐曲轴热模锻成形工艺方案设计及数值模拟分析

Process scheme design and numerical simulation analysis on hot die forging for 34CrNiMo6 steel three-turn crankshaft

以某款材质为34CrNiMo6高强度结构钢的三拐曲轴为研究对象,通过数值模拟与工艺实验相结合的方法,开发热模锻成形工艺方案。首先,研究该三拐曲轴用锻态34CrNiMo6高强度结构钢的高温流变行为,建立34CrNiMo6钢在DEFORM软件中的高温流变模型。其次,对初始工艺方案进行数值模拟,分析预锻件和终锻件的成形过程、填充情况、温度分布和等效应变分布。分析初始工艺方案下三拐曲轴平衡块充填不饱满的原因为:金属不易充填“高筋薄壁”的平衡块型腔而更容易从阻力较小的桥部流出,导致形成飞边。在此基础上,提出在模具局部增加阻力墙结构的改进工艺方案,数值模拟结果显示,预锻件和终锻件的充填效果均得到了有效提升。最后,采用带阻力墙的改进工艺方案进行工艺实验,结果表明,锻件充填饱满,无锻造缺陷。

For a three-turn crankshaft made of 34CrNiMo6 high strength construction steel,the hot die forging process scheme was developed by the combination of numerical simulation and process experiment.Firstly,the high temperature rheological behavior of as-forged 34CrNiMo6 high strength construction steel for the three-turn crankshaft was studied,and the high temperature rheological model of 34CrNiMo6 steel was established by software DEFORM.Secondly,the initial process scheme was simulated to analysis forming process,filling situation,temperature distribution and equivalent strain distribution of pre-forging and final forging parts,and the three-turn crankshaft balance block was not fully filled.The reason was that the metal was hard to fill the“high rib and thin wall”balance block cavity and it was easier to flow out from the bridge with less resistance to form flash.On this basis,a modified process scheme was proposed to add a resistance wall structure in the local part of die.The numerical simulation results show that the filling effect of pre-forging and final forging parts is effectively improved.Finally,the process experiment was carried out with the modified process scheme of adding resistance wall,and the results show that the forgings are fully filled and no forging defects.