4032铝合金活塞的热模锻变形过程有限元分析

Finite element analysis on hot die forging deformation process for 4032 aluminum alloy piston

为了深入研究4032铝合金活塞在热模锻过程中的材料变形特性,建立了典型活塞热模锻工艺的热-塑耦合有限元模型,详细研究了坯料的不同变形区域在锻造过程中的温度场变化、材料流动规律和应力、应变状态,进而分析了活塞锻件的预期力学性能和潜在锻造缺陷产生机理。模拟获得了锻造力曲线和锻件外形尺寸,通过对比模拟结果与实际锻件的关键几何参数,验证了有限元模型的合理性。模拟结果指出:材料变形由上模的冲孔和反挤压运动产生,材料变形区集中于上模冲孔面和台阶面附近,坯料在锻造过程中整体处于三向压应力状态;活塞内表面微小折叠、划伤、材料剥离等锻造缺陷和活塞裙填充不足、高度不均匀等工艺问题,主要是由模具的摩擦作用和材料流向的突变导致,实际生产过程应严格控制上模的表面精度和润滑效果,并应注意模具轴向棱边的圆滑设计。

In order to study the deformation characteristics of 4032 aluminum alloy piston during the hot die forging process deeply,a thermo-plastic coupled finite element model of hot die forging process for a typical piston was established,and the temperature field,the flow law of materials and the strain-stress state at the different deformation areas of blank during the forging process were studied in detail.Then,the expected mechanical performance and the mechanism of potential forging defects for the forged pistons were analyzed.Furthermore,the forging force curve and the overall dimension of the forged pistons were obtained,and the rationality of the finite element model was verified by comparing the simulation results with the key geometric parameters of the actual forged pistons.The simulation results show that the material deformation of piston is caused by piercing and backward extruding of upper die,the material deformation mainly occurs in the areas near the piercing and stepped surfaces of upper die,and the blank is in a three-way compressive stress state during the forging process.In addition,the forging defects such as micro-folding,scratching,material peeling on the inner surface of piston and the process problems such as insufficient filling and height unevenness of piston skirt are mainly caused by the friction of die and the sudden change of material flow directions.Thus,the surface precision and the lubrication effect of upper die should be strictly controlled,and the smooth design on the axial edges of die should be paid attention in the actual production process.