(硕士论文)Y型三通管内高压成形工艺优化及实验研究.pdf

哈尔滨工业大学工学硕士学位论文
摘要
为了提高不锈钢排气歧管的可靠性,改善排气性能,提出采用内高压工
艺来成形排气歧管中的 Y 型三通管。由于 Y 型三通管形状非对称、变形量
大,需综合控制压力、两端轴向补料量、枝管冲头后退量,各量之间的匹配
关系等各个工艺参数,成形难度很大。本文通过大量数值模拟和实验研究,
给出了 Y 型三通管内高压成形工艺优化的途径,并成功研制了 Y 型三通管
样件。
首先采用弹塑性有限元法对 Y 型三通管的内高压成形过程进行了数值
模拟,模拟中采用了多种压力路径、补料比和中间冲头后退量,并相应地进
行了实验验证。
结合模拟和实验结果,分析了压力对成形中的缺陷和成形后试件壁厚分
布的影响,指出压力过低会导致起皱缺陷,并给出了成形三通管合适的压力
范围和不同压力下成形试件的壁厚变化规律。
在合适的压力基础上,进一步的分析了补料比对枝管壁厚分布的影响,
给出了获得最佳壁厚分布的补料比范围,为控制轴向补料量提供了理论指
导。
分析了中间冲头后退量和中间冲头端面角度对枝管高度和试件壁厚分布
的影响,给出了合适的中间冲头后退量范围和中间冲头端面角度。同时还对
中间冲头后退的速度过快和后退过早引起的缺陷进行了分析,给出了避免缺
陷的后退速度和后退起始时刻。
研究揭示了 Y 型三通管成形过程中坯料金属的流动和壁厚演化规律,
以及起皱和破裂等缺陷的形成机理和防止措施,获得了该 Y 型三通管内高
压成形的优化工艺参数。
关键词 Y 型三通管;内高压成形;液压成形;排气歧管
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哈尔滨工业大学工学硕士学位论文
Abstract
Exhaust ponents such as Y-shaped tube are required to be
manufactured by tube hydroforming in order to improve the reliability and ability
of exhaust. It is difficult to form the Y-shaped tube because Y-shaped tube is an
asymmetric part with a bulky deformation and the relation of internal pressure
versus axial feed and withdraw of the branch punch must be determined together.
In the paper, abundant numerical simulation analyses and experiments
verification had been utilized to study the Y-shaped tube. The optimization
process of hydroforming of Y-shaped tube was presented, then the sample of Y-
shaped tube was manufactured essfully.
First, the elastic-plastic finite element model was set up to study the
hydroforming process of Y-shaped tube. All kinds of internal pressure, axial feed
ratio and branch punch displacement were studied in simulation, then
experimental verifications were carried out.
The effects of internal pressure on failure during hydroforming and
thickness distribution of formed parts are discussed bining the results of
simulations and experiments. It is indicated that severe wrinkles are likely to
occur because of insufficient internal pressure. Reasonable range of internal
pressure for hydroforming of Y-shap