共查询到19条相似文献,搜索用时 156 毫秒
1.
双金属薄壁管冲击液压胀形技术是在液压胀形与冲压成形基础上发展起来的一种复合成形技术。冲击液压载荷作用下的双金属薄壁管成形所需内压力源自于管坯型腔体积的压缩,其大小随液体体积压缩量变化而变化,为此提出了基于冲击液压载荷作用下双金属薄壁管的内压力形成机理的研究。首先介绍了双金属薄壁管冲击液压胀形的成形原理;然后,通过对内外管轴向冲击液压预成形与径向冲击液压成形过程中内压力形成的理论分析,构建了管坯型腔内压力与体积变化之间的数学模型;同时,利用Ansys Workbench有限元模拟技术获得了内外管轴向冲击液压预成形与径向冲击液压成形过程的内压力,通过有限元模拟与理论分析结果的对比发现,两者具有较好的一致性,并通过模型误差优化了内压力数学模型,为双金属薄壁管冲击液压胀形技术的进一步研究奠定了良好的理论与应用基础。 相似文献
2.
3.
介绍了小型汽车桥壳的液压胀形工艺,提出了初始胀形内压的表达式,预测了初始胀形内压与轴向推力的匹配关系(即经向应力比的大小)对预胀形时各部分变形顺序的影响。在普通液压机上进行了两种加载路径下的液压胀形试验,在初始经向应力比小于零并保持恒内压的条件下,预胀形管坯先变形成两侧高、中部低的双鼓形,经增压后将中部胀起;在初始经向应力比大于零且内压恒定的条件下,预胀形管坯中部沿轴向胀裂;两种加载路径下,管坯扁锥体凸起与胀形区之间均产生了明显内凹缺陷。理论分析与试验结果均表明,初始变形条件对小型桥壳的预胀形有重要影响。 相似文献
4.
5.
离散体颗粒介质使颗粒介质内高压成形工艺中的传压具有非均匀性、颗粒介质与管件之间摩擦作用显著等特征,基于此,建立了颗粒介质非均匀载荷传压模型,对凸环管件胀形工艺过程进行了理论推导和数值解析,探讨了内压状况和摩擦条件对管件成形性能的影响,并通过工艺试验对理论分析结果进行了验证。分析结果表明,颗粒介质内高压成形工艺所具有的内压非均匀性、介质与管坯摩擦作用显著两大特征可有效减小胀形过程中的壁厚减薄和成形压力。对比试验与理论分析结果表明,壁厚分布和成形压力的理论计算结果与试验结果一致,颗粒介质非均匀载荷传压模型的构建策略可用于管件成形的预测和分析。 相似文献
6.
7.
8.
9.
10.
11.
B. Yang W.G. Zhang S.H. Li 《The International Journal of Advanced Manufacturing Technology》2006,29(5):453-458
To investigate the effect of the loading path on the forming result and get the reasonable range of the loading path in tube
bulge hydroforming process, a mathematical model considering the forming tube as an ellipsoidal surface is proposed to examine
the plastic deformation behavior of a thin-walled tube during the tube bulge hydroforming process in an open die, and thus
different loading paths are gained based on this model. The finite element code Ls-Dyna is also used for simulating the tube
bulge hydroforming process. The effect of the loading paths on the bulged shape and the wall thickness distribution of the
tube are discussed, and then the reasonable range of the loading path for the tube bulge hydroforming process is determined. 相似文献
12.
B. Yang W. G. Zhang S. H. Li 《The International Journal of Advanced Manufacturing Technology》2006,29(5-6):453-458
To investigate the effect of the loading path on the forming result and get the reasonable range of the loading path in tube
bulge hydroforming process, a mathematical model considering the forming tube as an ellipsoidal surface is proposed to examine
the plastic deformation behavior of a thin-walled tube during the tube bulge hydroforming process in an open die, and thus
different loading paths are gained based on this model. The finite element code Ls-Dyna is also used for simulating the tube
bulge hydroforming process. The effect of the loading paths on the bulged shape and the wall thickness distribution of the
tube are discussed, and then the reasonable range of the loading path for the tube bulge hydroforming process is determined. 相似文献
13.
14.
Bing Li T.J. Nye Don R. Metzger 《The International Journal of Advanced Manufacturing Technology》2006,28(1-2):23-30
Tube hydroforming is an attractive manufacturing technology which is now widely used in many industries, especially the automobile
industry. The purpose of this study is to develop a method to analyze the effects of the forming parameters on the quality
of part formability and determine the optimal combination of the forming parameters for the process. The effects of the forming
parameters on the tube hydroforming process are studied by finite element analysis and the Taguchi method. The Taguchi method
is applied to design an orthogonal experimental array, and the virtual experiments are analyzed by the use of the finite element
method (FEM). The predicted results are then analyzed by the use of the Taguchi method from which the effect of each parameter
on the hydroformed tube is given. In this work, a free bulging tube hydroforming process is employed to find the optimal forming
parameters combination for the highest bulge ratio and the lowest thinning ratio. A multi-objective optimization approach
is proposed by simultaneously maximizing the bulge ratio and minimizing the thinning ratio. The optimization problem is solved
by using a goal attainment method. An example is given to illustrate the practicality of this approach and ease of use by
the designers and process engineers. 相似文献
15.
Sang-Woo Kim Woo-Jin Song Beom-Soo Kang Jeong Kim 《The International Journal of Advanced Manufacturing Technology》2009,41(3-4):311-322
In tube hydroforming, circular components are hydrobulged or hydroformed from tubular blanks with internal pressure and simultaneous axial loading. Thus the tube can be fed into the deformation zone during the bulge operation allowing more expansion and less thinning without any defects such as wrinkling, buckling, and bursting. By contrast with the buckling and the wrinkling, the bursting is generally classified as an irrecoverable failure mode. Hence in order to obtain the sound hydroformed products, it is necessary to predict the bursting behavior and to analyze the effects of process parameters on this failure condition in hydroforming processes. In this study, a forming limit stress diagram (FLSD) is constructed by plotting the calculated principal stresses based on the local necking criterion. Using the theoretical FLSD, we carry out the numerical prediction of bursting failure in a hydroforming process, which usually has non-linear strain path. Finite element analyses are carried out to find out the state of stresses during simple hydroforming operation, in which the FLSD is utilized as the forming limit criterion for assessment of the initiation of necking, and influences of the material parameters on the formability are investigated. In addition, the numerical results obtained from the FEM combined with the FLSD are confirmed with a series of bulge tests in view of bursting pressure and show a good agreement. Consequently, it is shown that the theoretical and numerical approach to bursting failure prediction proposed in this paper will provide a feasible method to satisfy the increasing practical demands for assessment of the forming severity in hydroforming processes. 相似文献
16.
17.
Xianfeng Chen Shuhui Li Zhongqi Yu Zhongqin Lin 《The International Journal of Advanced Manufacturing Technology》2012,61(1-4):87-100
This paper proposes a set of experimental approaches to establish the forming limit curve (FLC) in different forming modes for tube hydroforming. In tension–compression strain state, analytical models are constructed to determine the linear strain paths at the pole of the hydroformed tube, and a self-designed free hydroforming apparatus with axial feeding and internal pressure are used to carry out the bulge tests. In plane strain state, the difference is that both ends of the tube are fixed with different punches. In tension–tension strain state, a novel hydroforming apparatus are designed. The novel device requires the simultaneous application of lateral compression force and internal pressure to control the material flow under tension–tension strain states. The linear strain paths for the right hand side of FLC by finite element method simulation are calculated. The linear strain paths in different strain states are verified and the FLC of roll-formed QSTE340 seamed tube is constructed through the proposed experimental approaches. Comparison between simulation and experimental results for hydroforming process of front crossmember shows that the experimental FLC is accurate and valid for tube hydroforming. 相似文献
18.
Kourosh Hasanpour Mahmoud Barati Behnaz Amini Mehrdad Poursina 《Journal of Mechanical Science and Technology》2013,27(3):783-792
Rotary draw tube bending is one of the most complex tube forming processes subject to different process parameters such as material properties and geometry. This process is being practiced in more and more applications in industry due to its high efficiency, high forming precision and quality. However, improper process parameters can lead to wrinkling which restrict the thin walled tube bending. Therefore, the prediction and prevention of wrinkling is very important. Despite its importance, the effect of anisotropy on the occurrence of wrinkling was not considered in the literature up to now. In this investigation, a quantitative study on the wrinkling of thin walled tube bending is carried out through a finite element model of the process using velocity integral parameter, which is used for the detection of wrinkles. The other methods usually warn the wrinkling initiation with no precise location prediction. In addition, the effects of some process parameters, specially normal and planar anisotropy on the tube wrinkling are investigated. It is shown that increasing normal and planar anisotropy (increasing r0 and r90 values) result in a decrease in tube wrinkling. 相似文献
19.
Analytical and numerical approach to prediction of forming limit in tube hydroforming 总被引:1,自引:0,他引:1
Jeong Kim Sang-Woo Kim Woo-Jin Song Beom-Soo Kang 《International Journal of Mechanical Sciences》2005,47(7):1023-1037
Analytical and numerical analyses of forming limit in tube hydroforming under combined internal pressure and independent axial feeding are discussed in this paper. To predict the initiation of necking, Swift's criterion for diffuse plastic instability is adopted based on Hill's general theory for the uniqueness to the boundary value problem. In addition, in order to predict fracture initiation, Oyane's ductile fracture criterion is introduced and evaluated from the histories of stress and strain calculated by means of finite element analysis. From the comparison with a series of tube bulge tests, the prediction of the bursting failure based on the plastic instability and the ductile fracture criterion demonstrates to be reasonable so that these approaches can be extended to a wide range of practical tube hydroforming processes. 相似文献