油泵齿轮轴精锻成形工艺研究及缺陷分析

Forming process study and defect analysis of precision forging for the gear shafts of oil pumps

针对油泵齿轮轴特殊形状设计了齿轮轴精锻模具.通过有限元仿真和精锻实验研究了齿轮轴成形过程和金属流动规律.分析了对油泵齿轮轴精锻工艺中产生齿形角隅填充不满缺陷的原因:角隅填充是成形终了时成形载荷陡增的主要原因之一,由于齿轮轴精锻模具结构的特殊性,其强度无法满足齿形角隅填充所需高成形载荷的需要.基于角隅填充状况,提出了齿形端面斜面分流和环形槽分流,并对传统精锻工艺和两种分流锻造工艺进行了有限元仿真.分析结果表明两种分流方法均能有效减小齿形角隅填充时金属流动阻力,保证齿形良好填充,降低成形载荷,并且斜面分流优于环形槽分流.锻造实验验证了有限元仿真的准确性.

A special die of precision forging was designed for gear shafts. Metal forming and flow in the forging process were studied by finite element method and forging trials. The cause of tooth filling defects in the precision forging was analyzed： filling of the tooth corner is one of the key influence factor of a sharp rise of forming load. The forging die cannot bear the high load of fully corner filling due to its special structure. Based on the analysis of corner filling,chamfered relief and annulus relief were proposed for the precision forging. Finite element method was used for simulating the two relief processes and the conventional precision forging of gear shafts. It is shown that the two relief processes can both reduce the resistance of metal flow into the tooth corner,ensure well filling of the tooth corner and low forming load. Moreover,chamfered relief is better than annulus relief in the precision forging. Forging trials proved the validity of finite element simulation.