共查询到19条相似文献,搜索用时 328 毫秒
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拉弯成形可以有效地减少回弹,实现型材的高精度弯曲,因此拉弯成形在飞机、汽车型材弯曲件的生产中得到了广泛的应用.针对型材的拉弯成形,从型材力学性能、截面形状、工艺参数3个方面阐述了目前的研究状况及所取得的成果. 相似文献
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汽车工业是国民经济的支柱产业。而汽车门框、窗框、流水檐、车身外饰条、行李架等则是一些零部件生产厂商的主导产品,这些产品都是由各种型材弯曲成形的,截面复杂,空间形状多为三维,见图1。随着汽车工业发展的需求,型材拉弯工艺 相似文献
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《机械工程材料》2010,(12)
基于LS-DYNA软件平台对6061-T6铝合金汽车前碰撞横梁拉弯成形过程中的回弹量进行了模拟;研究了预拉力、补拉力和摩擦因数对回弹量的影响,并对拉弯模具孤面进行修正以补偿回弹量,最后进行了试验验证。结果表明:预拉力的变化影响型材横截面内的应力分布情况,随着预拉力增大至型材横截面积与材料屈服强度的乘积(Aσ_s)时,回弹量减小;在一定范围内,随着补拉力从Aσ_s逐渐增大,有利于减小拉弯成形件的回弹量;摩擦因数越大,回弹量越大;通过修正模具的弧面尺寸可以补偿回弹量;模拟结果与试验结果吻合较好,所建立的有限元模型能准确预测汽车前碰撞横梁的拉弯成形回弹量。 相似文献
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汽车门框上条件拉弯成形过程的数值模拟研究 总被引:1,自引:0,他引:1
复杂截面型材的高精度拉弯成形是制造汽车门框的关键技术。基于动态显式有限元软件ABAQUS/Explicit,针对一种由SPCD与B250P1拼焊板滚压得到的汽车门框上条型材零件,对其力控制方式的直进台面式拉弯成形进行了数值模拟研究,对比分析了不同预拉力和不同摩擦系数对型材截面畸变的影响程度。结果表明,增加预拉力可以减小截面畸变程度,但当预拉力大于1.3倍屈服强度时,畸变量反而变大,当预拉应力取1.1倍的屈服强度时,整体的畸变量达最小;当摩擦系数为0.08~0.12时,截面畸变量较小,可以得到较好的成形精度。 相似文献
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Ji-cai Liang Song Gao Fei Teng Pei-zhou Yu Xiang-jun Song 《The International Journal of Advanced Manufacturing Technology》2014,71(9-12):1939-1947
As the consumption of fossil energy from the traffic system increases, the need for 3D structural parts which provide the design engineer a lighter, stiffer, and more energy-efficient structure is required. A new flexible 3D stretch bending process (FSB) with multi-points dies (MPD) is thus being developed. This study seeks to find out the relationship between the springback error and the adjustment parameters for the FSB process. At first, the structure of flexible fundamental unit (FFU) with four degrees of freedom (DOF) MPD was designed and implemented. Then the FSB experiments with different bending radius of curvature and materials were carried out based on prototype of the flexible 3D stretch bending equipment. The experiment results show that the springback error increased linearly along the length of the workpiece. Without using the post-stretch force, the springback error declined from 7.90 % to 0.80 % by adjusting the positions of the FFU. Most importantly, the surface defects of the forming parts such as wrinkle and crack can be eliminated in this process. 相似文献
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提出一种适用于大型锥形件的缩口成形方法,通过主应力法对该缩口成形时的轴向缩口力与标准直壁锥形件的缩口力进行对比,得出了最佳成形方案。并基于Deform和响应曲面法讨论了该成形模具中缩口凹模母线弦高χ、内壁直空比l/h和毛坯壁厚S0、变壁厚尺寸λ分别对缩口件高度和缩口成形力的影响,得到了两个响应变量分别关于四个自变量的回归预测模型,优化出凹模内直空结构和毛坯的最佳几何结构参数,最后通过物理试验得到验证。结果表明:当χ=6.9 mm、l/h=0.3、S0=29.5 mm、λ=4.8 mm时,毛坯在缩口过程中未发生失稳,实时最大缩口力为1 920 kN,测量缩口件高度为1 108 mm,与模型预测结果误差均小于10%,说明了该工艺方案中缩口凹模和毛坯结构参数的可行性,其成形工艺及模具结构形式将为大型锥形产品的缩口成形提供理论指导。 相似文献
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回弹是材料弯曲成形过程中的主要影响因素之一,严重影响着弯曲件的质量与精度。在已有研究的基础上,对弯曲回弹的影响因素及控制措施做了综合有效深入的研究与分析,对工业生产有一定的现实意义。 相似文献
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Most of the existing studies use constant force to reduce springback while researching stretch force. However, variable stretch force can reduce springback more efficiently. The current research on springback prediction in stretch bending forming mainly focuses on artificial neural networks combined with the finite element simulation. There is a lack of springback prediction by support vector regression(SVR). In this paper, SVR is applied to predict springback in the three-dimensional stretch bending forming process, and variable stretch force trajectory is optimized. Six parameters of variable stretch force trajectory are chosen as the input parameters of the SVR model. Sixty experiments generated by design of experiments(DOE) are carried out to train and test the SVR model. The experimental results confirm that the accuracy of the SVR model is higher than that of artificial neural networks. Based on this model, an optimization algorithm of variable stretch force trajectory using particle swarm optimization(PSO) is proposed. The springback amount is used as the objective function. Changes of local thickness are applied as the criterion of forming constraints. The objection and constraints are formulated by response surface models. The precision of response surface models is examined. Six different stretch force trajectories are employed to certify springback reduction in the optimum stretch force trajectory, which can efficiently reduce springback. This research proposes a new method of springback prediction using SVR and optimizes variable stretch force trajectory to reduce springback. 相似文献
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板料成形都存在回弹,因回弹使得板料零件无法满足使用要求。论文围绕实际工件回弹的情况,通过有限元CAE方法,探讨了预成形压力、摩擦系数、间隙等主要因素对回弹的影响。并提出了减小回弹的几种方法,经实际验证效果良好。 相似文献
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《Journal of Mechanical Working Technology》1982,6(1):5-21
In the industrial forming of metal sheet or plate components by means of a bending operation, a constant problem is the change of shape, or “springback”, of the formed part under the elastic stresses that are released when the forming pressure is removed. For the close-tolerance forming of such components, an accurate means of calculating the springback is of great value, as this enables a corrective allowance to be made when designing and performing the forming operation itself. In the present paper, the influence of axial force on the elastic-plastic bending and springback of a beam is examined. After obtaining the fundamental relationship between the curvature of the beam and the load for the case of pure bending, both the elastic-plastic bending of a cantilever subjected to a concentrated force at its tip and the springback are considered. It is shown that the analysis can be applied to the press-brake bending of strips and the equibiaxial bending of plates. 相似文献
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橡皮囊成形是飞机钣金零件的一种重要成形工艺方法,回弹问题是橡皮囊成形的难点,对其影响因素进行显著性分析可有效控制回弹。基于橡皮囊成形有限元数值模拟,将正交试验设计方法与灰色关联度相结合用于分析橡皮囊成形回弹影响因素的显著性,以某实际长直U形件为例分析压力、最大充液速率、最大节点速度、保压时间、弯曲半径、板料厚度以及轧制方向等因素对回弹的影响程度,结果表明,模具圆角半径、压力、板料厚度、保压时间是橡皮囊成形回弹的主要影响因素,而最大充液速度、最大节点速度、轧制方向对回弹的影响较小。分析结果与工艺试验结果相吻合,从而验证了该方法的有效性。 相似文献
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Maziar Ramezani Zaidi Mohd Ripin Roslan Ahmad 《The International Journal of Advanced Manufacturing Technology》2010,46(1-4):101-110
The Stribeck friction model was investigated in this study to predict springback of high-strength steel sheets. The coefficient of friction in Stribeck curve depends on sliding velocity and contact pressure. The plane-strain bending process is simulated in ABAQUS/Standard. The influence of forming speed, over-pressing and holding time on springback behaviour of sheets was studied numerically. By plotting the variation of bending angle with punch stroke, we found that the loading curve of finite element analysis showed similar results to the experiments. The unloading curves of FE analysis with friction models based on Stribeck curve and Coulomb law showed good agreement with experiments with error less than 1.5%. Forming speed of up to 50 mm/s does not have significant effect on springback. The effect of holding time on reducing springback is small, but over-press has large effect on reducing springback. The results showed that Stribeck model is suitable for sheet metal forming simulations, especially at higher forming speeds and pressures. 相似文献
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管线钢管JCO精确弯曲成形技术 总被引:2,自引:0,他引:2
为了减小管线钢管JCO成形工艺中成形管坯的椭圆度,基于塑性弯曲工程理论和机器视觉测量技术提出了管线钢管JCO精确弯曲成形工艺。在管坯首道次成形过程中,采用两次预弯法,识别出板材的弹复规律,结合管坯目标成形角,预测出精确的压制行程;在后续成形道次中,利用误差补偿技术循环补偿上一道次的成形误差,实现管坯每道次精确弯曲成形。确定了适合管坯端面的图像处理算法、图像处理流程和直线检测算法,提出了采用正三角形作为标定模板求解摄像机外部参数的标定方法,由单幅图片快速、高精度地标定出摄像机的外部参数,建立了将图像角转换为管坯真实成形角的数学模型。实验结果表明,管坯成形角监测误差在0.2°以内,可控制成形管坯的椭圆度在1.5%以内,减小了成形管坯的椭圆度,改变了成形管坯的椭圆度控制依赖于操作者经验的现状。 相似文献