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Study of Deformation Behavior of Tubes in Tube Hydroforming

管材液压成形中管材变形行为研究

基本信息

批准号：
11650733
负责人：
FUCHIZAWA Sadakatsu
金额：
$ 1.66万
依托单位：
Utsunomiya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650733/
关键词：
Hydroforming Hydraulic bulging Thin-walled tube Deformation characteristics ハイドロフォーシング

项目摘要

First of all, tensile test and hydraulic bulging test were carried out to clarify basic deformation behavior of tubes. The tubes in our study were made of aluminum alloy, copper, steel and titanium. In the hydraulic bulging tests, in-plane stress ratio in the tube specimen was controlled. Summaries of the results are as follows. 1. It is possible to describe their strain hardening behavior using n-th power hardening law. 2. The strain hardening characteristics change depending on the amount of strain. It is roughly divided into two region, small strain region and large strain region. 3. Strain hardening of the titanium tube depends on in-plane stress ratio. The effect of in-plane stress ratio did not appeared in the experimental results with the other materials.In tube hydroforming, internal pressure and axial feeding are loaded to tube. Tube easily bursts when internal pressure is relatively larger than axial feeding. However, tube buckles when axial feeding is relatively larger than internal pressure. According to our experimental examination, it was clarified that there were two adequate loading methods to achieve large tube expansion without failures. One is the linear loading path where axial feeding is proportional to internal pressure. The other is the bilinear loading path where axial feeding is applied under a constant internal pressure. In the linear loading path, it is possible to find adequate ratio between internal pressure and axial feeding. On the other hand, there is an adequate value of internal pressure in the bilinear loading path.A model for FEM simulation was constructed and a forming die with square cross section was manufactured to examine the FEM simulation results. Through the FEM simulation and the experiment, it was confirmed that effect of friction between tube and the forming die clearly appeared in distribution of tube wall thickness.

首先进行了拉伸试验和液压胀形试验，明确了管材的基本变形行为。我们研究的管子由铝合金、铜、钢和钛制成。在液压胀形试验中，控制管试件的面内应力比。结果总结如下。1. 用n次幂硬化定律可以描述其应变硬化行为。2. 应变硬化特性随应变量的变化而变化。它大致分为两个区域，小应变区和大应变区。3. 钛管的应变硬化取决于面内应力比。在其他材料的实验结果中没有出现面内应力比的影响。在管材液压成形过程中，内压和轴向进给量被加载到管材上。当内压相对大于轴向进料时，管容易破裂。然而，当轴向进料相对大于内压时，管屈曲。根据我们的实验检查，明确了有两种足够的加载方法来实现大的管膨胀而不破坏。一种是线性加载路径，轴向进给量与内压成正比。另一种是双线性加载路径，在恒定的内压下施加轴向进料。在线性加载路径中，可以找到适当的内压与轴向进给比。另一方面，在双线性加载路径中存在足够的内压值。建立了有限元模拟模型，制作了方形截面的成形模具，对有限元模拟结果进行了验证。通过有限元模拟和实验，证实了管材与成形模之间的摩擦对管壁厚度分布的影响较为明显。