空心双拐曲轴加载路径优化与成形规律

Loading Paths Optimization and Forming Rules of Hollow Double-throw Crankshaft

目的研究加载路径对空心双拐曲轴成形效果的影响。方法基于有限元分析软件,对304不锈钢双拐曲轴内高压胀形工艺进行有限元仿真,分析了加载路径对双拐曲轴胀形高度与壁厚的影响,并对开裂、起皱等缺陷产生的原因进行分析,最后,根据数值模拟结果,对双拐曲轴进行实际成形试验,并将数值模拟结果与试验结果进行对比。结果成形压力小于20 MPa时,管坯产生起皱;成形压力大于60 MPa时,管坯产生开裂。通过试验获得了壁厚分布均匀的双拐曲轴零件,并且数值模拟结果和试验结果基本一致。结论轴向进给大、内压不足容易导致过渡圆角处起皱;轴向进给小、内压过大容易导致拐部顶端开裂。只有设置合理的加载路径才能成形出壁厚均匀性好,胀形高度达到要求的双拐曲轴。

The work aims to study the effects of loading paths on the formability of hollow double-throw crankshaft. Finite element simulation of hydroforming processes of 304 stainless steel hollow double-throw crankshaft was conducted by using finite element analysis. During the simulation, the effects of loading paths on bulging height of the double hollow crankshaft and thickness distribution were studied and the causes of defects such as cracking and wrinkling were analyzed. Finally, according to the results of the numerical simulation, the actual forming experiment was conducted. The numerical simulation results were compared with the experimental results. Winkling occured on pipe bilet as the forming pressure was < 20 MPa and cracking occured as the forming pressure was > 60 MPa. In the experiment, parts of double-throw crankshaft with uniformly distributed wall thickness were obtained. And the numerical simulation results were basically consistent with test results. High axial feed and insufficient internal pressure may cause wrinkling in transition corners; low axial feed and excessive pressure may bring about severe thickness reduction and even cracking in the throw parts. Only when reasonable loading path is set up, an eligible double-throw crankshaft of good wall thickness uniformity and buldging height can be successfully manufactured.