长轴类大变截面复杂锻件精确成形缺陷控制
Defect Control Method in Precise Forming for Complex Long-axis Forgings with Great Varying Cross-section
陈锡侯1, 王梦寒2， 向 东2
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作者单位：(1. 重庆理工大学 机械检测技术与装备教育部工程研究中心 重庆 400050；2. 重庆大学 材料科学与工程学院， 重庆 400030)
中文关键字：精确塑性成形；缺陷控制；阻力墙；凸形连皮，模具寿命，金属流动控制
英文关键字：precision plastic forming; defect control; resistance wall; convex web; die life; metal flowing control
中文摘要：针对长轴类大变截面复杂锻件精确成形过程中存在充不满和模具寿命低的问题，采用数值模拟技术与生产试制结合的方法，研究了某微车四拐曲轴精确成形过程中上述两种缺陷形成的原因，提出了一种通过设计适合的预锻模来控制成形过程中金属流动状态、避免充不满和减少锻模磨损的方法。在该预锻模中，采用阻力墙形式构造飞边槽，采用凸形连皮结构连接多个大变截面。通过优化预锻模具的结构参数改善金属在模膛内的充模状态，实现长轴类大变截面复杂锻件精确成形过程中的缺陷控制。结果表明，在预锻模具中距模具型腔的位置为10 mm设置斜度为10°,间隙1～2.5 mm的阻力墙并采用中间厚度为18 mm的凸形连皮连接各个变截面，可以将四拐曲轴终锻模具的寿命由原来的每套4500件提高到每套7800件，将材料利用率由原来的66.2%提高到88.3%。
英文摘要：In precision forming process of complex long-axis forgings with great varying cross-section, the main defects are insufficient filling and short service life of dies. Focusing on these problems, the causes of above-mentioned two kinds of defects in precision forming process for crankshaft with four cylinder sleeve in a mini-car were discussed by combining numerical simulation technology with pilot production. A defect controlling method was proposed to avoid insufficient filling and reduce the wear of forging die, which designs a suitable pre-forming die to control the metal flow state. In the pre-forming die, a resistance wall was adopted to build the flash groove and a convex web structure was used to connect the great varying cross-sections. Through optimizing the structure parameters of the pre-forming die, the filling state of metal in the die improved and the defects of the complex forgings were controlled. The results show that the effect of the defects control is best when the pre-forming die has a resistance wall with a slope of 10°, a gap of 1～2.5 mm at the location of 10 mm away from die cavity and a convex web with a thickness of 18 mm. The life of the final forging die is improved from original 4500 pieces per set up to 7800 pieces per set, and the material utilization rate is improved from 66.2% to 88.3%.