组合形活塞销冷镦挤成形工艺

针对组合形活塞销结构特征和工艺要求,分析该零件的成形难点为:两端圆锥孔的挤压成形和深径比大于2. 5的中心圆孔反挤压。为此,应用DEFORM-2D有限元分析软件对组合形活塞销7工位冷镦挤成形工艺进行数值模拟分析。通过数值模拟分析和工艺方案修订,确定最终的成形工艺方案为:下料-整形-压凹-反挤压-冲孔-第1次挤锥-第2次挤锥,并采用硬质合金YG15制造反挤压凸模,以避免一次反挤压成形时凸模横截面变化处的折断。采用该方案进行工艺实验,实验结果表明:组合形活塞销尺寸满足零件设计要求,无折叠、开裂等锻造缺陷,深孔反挤压凸模使用寿命大于8万件。

Cold upsetting-extruding process for combination piston-pins

For structural characteristics and process requirements of combination piston-pins,its forming difficulties were analyzed as the extruding of tapered holes at both ends and the backward extrusion of central circular hole with a ratio of depth to diameter more than 2. 5,and the cold upsetting-extruding process of combination piston-pins with seven steps was simulated and analyzed by finite element analysis software DEFORM-2D. Through the numerical simulation analysis and the revision of the process scheme,the final forming process scheme was determined as blanking-sizing-upsetting-backward extrusion-piercing-the first extruding taper holes-the second extruding taper holes,and the backward extrusion punch was made of YG15 cemented carbide to avoid breakage where the cross section of punch changed in the backward extrusion. Using the final process scheme for production experiment,the experiment result shows that the combination piston-pin meets the design requirements of part without forging defects such as fold and crack,and the backward extrusion punch of deep hole has a service life of more than 80000 pieces.