共查询到18条相似文献,搜索用时 296 毫秒
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为探究汽车纵梁液压成形规律,并为其工程化应用提供必要的指导,对方形管进行脉动液压成形实验及数值模拟,并通过实验验证模拟的正确性。首先明确纵梁液压成形工序及主要参数,然后对其成形全过程进行仿真研究,最后基于此分析了液压加载路径、成形模具与管坯接触面间摩擦系数对纵梁液压成形壁厚分布及成形件最大减薄率的影响规律。结果表明:在常规加载中,前期增压至成形压力值一半左右,并进行一段时间的保压,后期升压至成形压力,其加载路径下的成形构件最大减薄率最小,壁厚分布整体最均匀;在此加载路径基础上,采用脉动加载可进一步提高其成形质量;同时,摩擦系数越小,成形最大减薄率越小,整体壁厚值越接近初始管坯值且分布越均匀。 相似文献
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目前液压胀形加载路径设计多属于试错法,路径调试缺乏系统的指导思想,没有量化的反馈,因此,提出了基于均匀增容的液压胀形加载路径的设计方法。以管坯内部容积随轴向推进量线性均匀变化为目标,将整个液压胀形过程分为若个子步,通过调整每一子步的管坯内部压力,使每一子步的管坯内部容积沿均匀增容线变化,得到液压胀形管件。以某大型汽车桥壳管件预成形管坯为例,通过数值模拟得到了均匀增容的加载路径,给出了基于均匀增容线的合理成形区间,进行了生产试验,得到了外形轮廓清晰、壁厚减薄率满足设计要求的合格样件,试验结果表明:基于均匀增容的液压胀形加载路径适用于实际生产,样件成品率高、成形性好。 相似文献
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铝镁合金双路径加载充液拉深成形的数值模拟 总被引:2,自引:1,他引:1
针对铝镁合金等低塑性板材的成形需要,提出了带主动径向加压的双路径加载充液拉深技术。应用数值模拟的方法,采用大型非线性动力显式分析软件ETA/Dynaform5.5,对5A06铝镁合金平底筒形件的双路径加载充液拉深成形过程进行研究,讨论液室压力变化对零件成形性的影响,以零件成形最终壁厚分布为评定标准,分析不同径向压力加载路径对成形质量的影响。模拟结果表明,采用合理的液室加载曲线,并配合20-45MPa的主动径向压力,可有效地提高铝镁合金平底简形件的成形极限,拉深比可达到3.1。 相似文献
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S.J. Yuan C. Han X.S. Wang 《International Journal of Machine Tools and Manufacture》2006,46(11):1201-1206
An experimental and numerical simulation was conducted to investigate hydroforming of automotive rectangular-section structural components and the results were used as guidelines for some prototypes. The effect of loading path on the failures and thickness distribution was discussed and the reasons were analyzed for the failures, such as bursting and folding. Hydroforming with axial feeding is strongly sensitive to the loading path. Bursting occurs in transition zone in the calibration when the internal pressure increases faster than the axial feeding. Otherwise, folding will take place due to too much axial feeding. There is the maximum thickness at central point of the side of cross-section and the minimum thickness at the transition area. If the n value of the tube material is bigger, the thickness of the final part will be more uniform. By using a petal-like perform section shape, the pressure for forming the transition radii was greatly reduced and components with small radii can be formed with relatively low pressure. 相似文献
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Loading path optimization of tube hydroforming process 总被引:3,自引:1,他引:3
M. Imaninejad G. Subhash A. Loukus 《International Journal of Machine Tools and Manufacture》2005,45(12-13):1504-1514
Optimization methods along with finite element simulations were utilized to determine the optimum loading paths for closed-die and T-joint tube hydroforming processes. The objective was to produce a part with minimum thickness variation while keeping the maximum effective stress below the material ultimate stress during the forming process. In the closed-die hydroforming, the intent was also to conform the tube to the die shape whereas in the T-joint design, maximum T-branch height was sought. It is shown that utilization of optimized loading paths yields a better conformance of the part to the die shape or leads to a higher bulge height. Finite element simulations also revealed that, in an optimized loading path, the majority of the axial feed needs to be provided after the tube material yields under the applied internal pressure. These results were validated by conducting experiments on aluminum tubes where a good correlation between the experimental results and simulations were obtained. 相似文献
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Based on the sidewall wrinkling phenomena in hydroforming of thin-walled Tee-joint, an analytical model for tube wrinkling under double side constraints was proposed to calculate the critical wrinkling stress. The effects of stress ratio, diameter-to-thickness ratio and tube material properties on critical condition of sidewall wrinkling were investigated. It is found that the middle of the main tube side wall is the most dangerous position for wrinkling within hydroforming of thin-walled Tee-joint. At a certain internal pressure, the critical wrinkling stress increases with increasing of ratio of hoop stress to axial stress and material strength coefficients, but decreases with increasing of work-hardening exponent and ratio of diameter to thickness. Through the analytical model combining FEM simulation, the critical wrinkling loading path according to the relation between axial feeding and internal pressure was obtained. Experimental results validates that wrinkle can be avoided if the pressure is above the critical wrinkling loading path, otherwise, wrinkle occurs. It is also verified that the analytical model of critical wrinkling stress is reasonable for the thin-walled Tee-joint hydroforming process. 相似文献
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Optimization of loading conditions for tube hydroforming 总被引:12,自引:0,他引:12
Tube hydroforming is a developing technology with advanced features of lightness and unified part. This study investigates the best possible regulation for loading conditions between the internal pressure and the axial feeding by hydroforming of a T-shape metal tube. Using conjugate gradient method with finite element method, a program module is generated to check the hydroformed tube quality about its thickness uniformity and the geometry accuracy. Thereby, a batch mode and a sequential mode to optimize the loading conditions of the tube hydroforming process are created and investigated. Regarding the tube quality from the simulation results, the hydroforming process, which follows the loading curve generated by the sequential mode, is better than by the batch mode. The optimal loading procedure generated by this article can offer another possibility for engineer by determining the internal pressure and the axial feeding in tube hydroforming. 相似文献
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薄壁不锈钢数码相机外壳液压成形工艺研究 总被引:2,自引:1,他引:1
数码相机外壳是形状复杂的非旋转体不规则结构薄壳形件,文章基于其工艺难点及形状特征分析,采用1Cr18Ni9Ti不锈钢板材进行了不同液压加载路径下的充液拉深成形实验,并结合有限元模拟,分析了液压加载与凸模运动的不同匹配关系对成形结果的影响;针对各种成形缺陷分析其产生原因,并确定了合适的成形工艺参数,模拟结果与实验吻合良好。在室温条件下,以1mm/s~2mm/s的凸模速度进行液压成形,在液压载荷最高为20MPa时,成功试制出表面质量好、结构精度高的薄壁不锈钢数码相机外壳。研究结果为复杂结构薄壳形件液压成形工艺参数的确定和优化设计奠定了基础,并为采用液压成形工艺生产和加工电子器件不锈钢外壳提供实验和理论依据。 相似文献
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Wrinkling behavior of magnesium alloy tube in warm hydroforming 总被引:1,自引:0,他引:1
In tube hydroforming with axial feeding, under the effect of coupled internal pressure and axial stress, wrinkles often occur and affect the forming results. Wrinkling behavior of an AZ31B magnesium alloy tube was experimentally investigated with different loading paths at different temperatures. Features of wrinkles, including shape, radius and width, were acquired from the experiments, as well as the thickness distribution. Numerical simulations were carried out to reveal the stress state during warm hydroforming, and then the strain history of material at the top and bottom of the wrinkles were analyzed according to the stress tracks and yielding ellipse. Finally, effects of loading paths on expansion ratio limit of warm hydroforming were analyzed. It is verified that at a certain temperature, expansion ratio limit can be increased obviously by applying a proper loading path and realizing enough axial feeding. 相似文献