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。
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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风机吊装
Exhaust system components 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 successfully.
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 by combining 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-shaped tube and the rule of wall thickness distribution for the parts with different internal pressure loading paths are acquired.
The prime range of axial feed ratio is got by analyzing the effect of axial feed ratio on wall thickness of protrusion at proper internal pressure. The results can be regarded as the theoretic base of the axial feed control.
The effects of the branch punch displacement and top angle on the height and wall thickness of the protrusion are discussed. The proper range of branch punch displacement and its top angle was acquired. The defects encountered as a result of the too early and too fast withdrawing of the branch punch are discussed. The proper withdrawing speed of the branch punch and the proper beginning time of the withdrawing are determined.
The rules of metal flow and wall thickness evolution in forming process are
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哈尔滨工业大学工学硕士学位论文
revealed. The reasons of wrinkle and burst and the method for preventing them are given out. Finally, the process parameters optimized are acquired.
Keywords Y-shape tube, internal high pressure forming, hydroforming, exhaust pipe
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哈尔滨工业大学工学硕士学位论文
目录
摘要...............................................................................................................................II 第1章绪论. (1)
1.1 引言 (1)
1.2 内高压成形工艺简介 (1)
1.2.1 内高压成形原理及工艺分类 (1)
1.2.2 内高压成形工艺的优点 (3)
1.3 枝杈管件的内高压成形工艺 (3)
1.4 内高压成形件在汽车排气系统中的应用 (4)
1.5 枝杈类管件内高压成形技术的国内外现状 (5)
1.5.1 十字型四通管现状 (6)
1.5.2 T型三通管现状 (6)
1.5.3 Y型三通管现状 (10)
1.6 课题的来源及意义 (11)
1.7 课题主要研究内容 (12)
第2章Y型三通管内高压成形的模拟和实验基础 (13)
2.1 引言 (13)
2.2 Y型三通管成形的几何分析 (13)
2.3Y型三通管成形的数值模拟模型 (15)
2.4 Y型三通管成形的实验研究基础 (17)
2.5 Y型三通管成形的关键工艺参数 (19)
2.6 本章小结 (20)
第3章压力对Y型三通管内高压成形的影响 (21)
3.1 引言 (21)
3.2 不同压力下成形的数值模拟 (21)
3.2.1 模拟方案及加载路径 (21)
可调高压电源
3.2.2 不同压力对成形缺陷的影响 (23)
3.2.3 起皱时的应变分析 (25)
3.2.4 不同压力对壁厚分布的影响 (27)
3.3 不同压力下成形的实验研究 (30)
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哈尔滨工业大学工学硕士学位论文
3.3.1 实验方案及加载路径 (30)
3.3.2 不同压力对成形缺陷的影响 (31)
3.3.3 不同压力对壁厚分布的影响 (33)
3.4 本章小结 (36)
第4章补料比对Y型三通管内高压成形的影响 (38)
4.1 引言 (38)
4.2 不同补料比的数值模拟 (38)
4.2.1 模拟方案及加载路径 (38)
4.2.2 不同补料比对壁厚分布的影响 (40)
4.3 不同补料比例的实验研究 (43)
4.3.1 实验方案及加载路径 (43)
4.3.2 不同补料比例对壁厚分布的影响 (45)
4.4 本章小结 (51)
第5章中间冲头对Y型三通管内高压成形的影响 (52)
5.1 引言 (52)
5.2 不同中间冲头后退量的数值模拟 (52)
5.2.1 模拟方案及加载路径 (52)
5.2.2 不同后退量对壁厚分布和枝管高度的影响 (53)
5.3 不同中间冲头后退量的实验研究 (56)
5.3.1 实验方案及加载路径 (56)低温空调
5.3.2 不同后退量对壁厚分布和枝管高度的影响 (57)
5.4 Y型三通管成形过程中的破裂 (59)
棒材矫直机5.4.1 中间冲头对破裂的影响 (59)
5.4.2 破裂时典型点的应变分析 (63)
5.5 不同中间冲头端面角度的数值模拟 (65)
5.5.1 模拟方案及加载路径 (65)
外室1H5.5.2 不同端面角度对壁厚分布和枝管高度的影响 (66)
5.6 不同中间冲头端面角度的实验研究 (68)
5.6.1 实验方案及加载路径 (68)
5.6.2 不同端面角度对壁厚分布和枝管高度的影响 (70)
5.7 Y型三通管成形过程分析 (72)
5.8 本章小结 (77)
结论 (78)
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