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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10mm设置斜度为10°,间隙1～2.5mm的阻力墙并采用中间厚度为18mm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%。
Aiming at the problems of unsatisfactory filling and low mold life during the precision forming process of complex forgings with large axial deformation, the two kinds of defects mentioned above were studied by the combination of numerical simulation and production trial. Forming a reason, proposed by designing a suitable pre-die to control the flow of metal during the forming process, to avoid dissatisfaction and reduce forging die wear method. In the pre-forging die, the flash tank is constructed by the form of a resistance wall, and a plurality of large-diameter cross-sections are connected by the convex skin structure. By optimizing the structural parameters of the pre-forging die, the filling state of the metal in the mold cavity is improved, and the defect control in the precise forming of the complex large-section long-axis cross-section forging is realized. The results show that in the pre-forging die, the distance from the mold cavity is 10mm, the resistance gradient wall with the slope of 10 ° and the clearance of 1 ~ 2.5mm is set, and the convex sections with the middle thickness of 18mm are used to connect the various cross sections. Crank crankshaft final forging die life from the original 4500 per set to improve to 7,800 per set, the material utilization increased from 66.2% to 88.3%.