钛合金环形管成形模具参数优化

Optimization of Die Parameters for Titanium Ring Pipe Formation

在MSC/Superform有限元模拟软件和弹塑性有限元理论的基础上,建立了钛合金环形管成形过程的计算机模拟系统。选取阿基米德螺旋线为牛角芯模中心线设计模具,采用中频感应加热方法,对阿基米德常数、扩径比、弯曲角度等模具参数进行优化模拟。分析可得:(1)阿基米德螺线系数的合理选取能够保证获得较好的壁厚均匀性,模拟得到本工艺较佳系数为1.0;(2)扩径比太大,容易出现起皱、减薄等缺陷;扩径比偏小,腹部增厚、壁厚均匀性降低,本工艺合适的扩径比为1.33;(3)弯曲角度太小,弯管成形过程变形剧烈,成形后弯管的力学性能等不能较好满足要求;弯曲角度太大,变形过程平稳,但随着推制阻力的增大导致推制困难,本工艺较佳弯曲角度为40o。通过正交试验方法验证得到:在上述参数条件下可以获得壁厚均匀、耐高压、等强度的钛合金环形管。

A computer simulation system of the ring pipe bending process of titanium alloys was established using MSC/Superform finite element simulation software on the basis of elastic-plastic finite element theory. The Archimedes spiral was selected as the center axis of the ox-horn die with small bending radius for maintaining the continuity of the curvature radius. Optimization simulation of die parameters such as Archimedes constant, expanding diameter ratio and bending angle was carried out by mid-frequency induction heating method. The conclusions are as follows： （1） the reasonable Archimedes constant can ensure the sound uniformity of the wall thickness and the optimized constant was 1.0 according to the simulation; （2） the too higher expanding diameter ratio would induce easily some defects such as crinkles and thickness-decrease, while the too lower ratio would induce thickness-increase of the abdomen and uniformity-decrease of the wall-thickness; thus the preferred ratio value was 1.33 for the process; （3） if the bending angle was too small, the pipe bending progress was severe and the mechanical properties of the obtained pipe could not satisfy the requirements well; if the angle was too large, the bending progress was stable, but the thrust became difficult as the increase of the thrust resistance; therefore, the preferred bending angle was 40° for the process. The titanium ring pipe with uniform wall thickness, high-voltage-resistance and equal strength was obtained using the above mentioned parameters, detected by the orthogonal test