轴向非对称中空型材拉弯过渡区长度优化

Optimization of transition zone length in stretch bending of axially asymmetric hollow profiles

摘要:

为探究过渡区长度对型材拉弯成形的影响,以高速列车用典型轴向非对称铝型材为对象,选取4种不同过渡区长度进行拉弯研究.利用数值模拟对比分析了成形后零件的应力应变分布、形状误差、回弹、截面畸变和空间扭转,并定义成形缺陷指数表征综合成形效果.结果表明,随着过渡区长度的增加,型材成形后的形状误差和回弹明显减小,但是截面畸变和空间扭转增大；成形缺陷指数表明,过渡区长度为200 mm时型材拉弯成形综合缺陷最小,利用0.618法优化了过渡区长度.在张臂式拉弯机上进行实验验证,测量结果和数值分析规律相吻合.

Abstract:

In order to study the influence of transition zone length on stretching bending, in this paper, typical asymmetric aluminum profile used in high-speed train was selected as the research object, and stretching bending research of four different transition zone length was carried out. Numerical simulation was used to analyze and compare stress and strain distribution, shape error, springback, cross-section distortion and spatial twist, and the forming defects index was defined to characterize the integrated forming effects. The results reveal that an increment of the post-stretching elongation leads to small shape error and springback but large cross-sectional distortion and spatial twist. The forming defects index illustrates that a 200 mm transition zone leads to the least forming defects for stretching bending. The 0.618 method was used to optimize transition zone length. Experimental validation was also conducted on stretch-wrap bending machine to show the consistence with the numerical analysis.