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介绍了金属板料渐进成形工艺的基本原理。以ANSYS/LS—DYNA为分析平台,构建了板料多道次渐进成形的有限元模型,并以LS—PREPOST和ETA/Post—Processor为后处理平台,得到各道次厚度云图及网格变形图。对半球形制件的三道次成形过程进行了模拟,将模拟结果与实验结果进行比较,证明了模拟的可行性。 相似文献
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针对多道次双点渐进成形中材料变形规律问题,建立了典型圆锥台件双点渐进成形有限元模型,采用螺旋轨迹对其多道次成形规律进行了数值模拟,对模拟结果中节点坐标和位移、单元应变和壁厚数据进行了提取,分析了成形过程中节点流动、单元应变及壁厚分布规律,并通过在实验板料表面印制圆形网格和制作标记点进行了多道次双点渐进成形实验,对成形零件网格变化、标记点径向移动和零件壁厚进行了测量分析,验证了模拟结果的正确性。研究结果表明,多道次双点渐进成形中材料产生明显的径向流动,且随着成形道次增多而增大,同时,成形道次越多零件壁厚均匀性越好;另外,采用变间隔角度设计方法,可改善多道次双点渐进成形零件壁厚分布均匀性,且随着成形道次增多作用越明显。 相似文献
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《制造技术与机床》2016,(11)
为改善大幅面曲面板材成形精度,提出一种渐进折弯成形新方法。以马鞍形曲面成形为例,采用平面应变和Mises各向同性屈服准则,建立基于ABAQUS/ExplicitStandard求解分析平台的板材三维弹塑性渐进折弯成形有限元模型,对板材渐进折弯与回弹全过程进行了数值模拟,结合试验研究,获得最优工艺参数。模拟及实验结果表明:采用曲面凸凹模及优化工艺参数可实现高精度大幅面曲面板材的成形,模拟成形工件的平均误差为+2.1/-1.8 mm,实验测量成形板材曲率与目标模型理论曲率误差较小,模拟结果与实验结果基本吻合,这对曲面冷弯成形技术的应用,具有重要的参考价值和指导意义。 相似文献
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《机械制造与自动化》2016,(6):11-16
基于ANSYS/LS-DYNA软件对外轮廓支撑渐进成形锥形件建立了相应的数值模型。以0.84 mm厚的1060Al为毛坯板料,在单道次渐进成形中模拟了大角度锥形件的成形过程,发现避开减薄带的新路径,可以有效提高其最大成形角度,并通过实验探索了不同工具头半径、轴向进给量等对最大成形角度的影响。对于超过此最大成形角度的锥形件,采用多道次渐进成形的工艺,先根据制件形状反向规划其成形路径,然后通过有限元模拟,调整路径参数,最后制得的大角度锥形件壁厚均匀,形状良好。 相似文献
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塑性成形领域中对钣金件非对称零件的两道次拉深成形一直是个难题。以非对称形件为研究对象,采用数值模拟和试验相结合的方法进行了研究。试验中采用网格法研究了两道次拉深后得到的成形件局部应变分布和第二道次成形件的壁厚变化。数值模拟中采用两道次连续成形的方法进行了仿真分析,根据仿真结果分析了成形性、应力、应变分布等,同时得到了对应试验结果仿真结果,并将试验结果和仿真结果进行了对比。结果表明,多道次有限元模拟中厚度变化与试验相差较小,可以通过有限元模拟预测多道次成形件厚度;多道次有限元模拟中应变分布与试验相差较小,可以通过有限元模拟预测多道次成形件成形性;采用多道次连续成形方法可以解决多道次成形中不同道次间材料属性变化难处理的问题。 相似文献
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实现了具有开放几何特征钣金件的渐进成形。提出采用工艺参数优化、多道次渐进成形和轨迹补偿等方法提高钣金件的几何精度。设计了多道次渐进成形方法的中间构型,目的在于增大材料塑性变形并减小几何偏差。采用层切法轮廓轨迹形成两道次成形中第一道次的构型,为了防止第一道次成形时出现破裂,将非固定方向的成形角度设定为75°,第二道次将非固定方向的板料完全成形。采用基于几何补偿的两道次渐进成形方法可以将开放几何特征钣金件的几何偏差控制在0.5 mm左右。 相似文献
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In this work it is assessed the potential of combining conventional and incremental sheet forming processes in a same sheet of metal.This so-called hybrid forming approach is performed through the manufacture of a pre-forming by conventional forming,followed by incremental sheet forming.The main objective is analyzing strain evolution.The pre-forming induced in the conventional forming stage will determine the strain paths,directly influencing the strains produced by the incremental process.To conduct the study,in the conventional processes,strains were imposed in three different ways with distinct true strains.At the incremental stage,the pyramid strategy was adopted with differ-ent wall slopes.From the experiments,the true strains and the final geometries were analyzed.Numerical simulation was also employed for the sake of comparison and correlation with the measured data.It could be observed that single-stretch pre-strain was directly proportional to the maximum incremental strains achieved,whereas samples subjected to biaxial pre-strain influenced the formability according to the degree of pre-strain applied.Pre-strain driven by the prior deep-drawing operation did not result,in this particular geometry,in increased formability. 相似文献
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Mould correction for sheet-metal multi-step incremental air-bending forming based on close-loop control and FEM simulation 总被引:3,自引:0,他引:3
Zemin Fu Jianhua Mo Pan Gong Wenxian Zhang Zhongwei Li Kui Huang 《International Journal of Mechanical Sciences》2009,51(9-10):732-740
There exist errors between the manufactured workpieces and the CAD models due to the springback of sheet-metal incremental air-bending forming. To reduce these errors, an off-line closed-loop control iterative algorithm, combined by fast Fourier and wavelet transform, is developed from the displacement adjustment method (DAM), smooth displacement adjustment method (SDAM) and deformation transfer function method (DTFM) for die surface. With this algorithm, the mould surface of sheet-metal incremental air-bending forming could be properly corrected, and the springback errors of the formed workpieces could be effectively reduced. In order to reduce mould cost and labor cost, the springback tests of workpieces forming, needed in the iterative process of closed-loop control system, are substituted by finite element model (FEM) simulation. The above correction algorithm was used in a semiellipse-shape workpiece incremental air-bending forming. Its average errors are +0.74/−0.39 mm. The results show that the mould correction algorithm with Fourier and wavelet transform is reasonable and the means of FEM simulation are effective. It can be taken as a new approach for sheet-metal multi-step incremental air-bending forming and mould design. 相似文献
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Zemin Fu Jianhua Mo Wenxian Zhang 《The International Journal of Advanced Manufacturing Technology》2009,45(5-6):448-458
A mathematical model of springback radius was developed with dimensional analysis and orthogonal test. With this model, the punch radius could be solved for forming high-precision semiellipse-shaped workpieces. With the punch radius and other geometrical parameters of a tool, a 2D ABAQUS finite-element model (FEM) was established. Then, the forming process of sheet metal multiple-step incremental air bending was simulated with the FEM. The result showed that average errors of the simulated workpiece were +0.68/?0.65 mm, and provided the process data consisting of sheet feed rate, punch displacement and springback angle in each step. A semiellipse-shaped workpiece, whose average errors are +0.68/?0.69 mm, was made with the simulation data. These results indicate that the punch design method is feasible with the mathematical model, and the means of FEM simulation is effective. It can be taken as a new approach for sheet metal multiple-step incremental air-bending forming and tool design. 相似文献
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Junchao Li Jianbiao Hu Junjie Pan Pei Geng 《The International Journal of Advanced Manufacturing Technology》2012,62(9-12):981-988
Sheet incremental forming (ISF) is a promising technology. It is inexpensive and does not require particular dies. Sheet thinning, however, has always been one of the forming defects which impede the process’s wide application. Although a multi-stage forming process is supposed to be effective to deal with this problem, it is still uncertain how the process can reduce thickness thinning and there is no applicable rule to determine the favorable number of forming stages. In this work, based on a truncated cone, a finite element method (FEM) model for a double-pass forming was established first. Unlike simplifications in previous studies, with the process of the three-dimensional coordinates in numerical controlled (NC) machining code, the tool trajectory in this simulation model is the same as that in real work. With this approach, it was expected to gain reliability of the simulation result, and then this simulation result and a single-pass forming result were analyzed. The results of the analysis indicate that more uniform thickness distribution in the double-forming process largely benefits from the increase of the total plastic deformation zone. Finally, under the condition of constant volume in deformation, an equation was proposed to work out the right number of necessary forming stages and the rule of this equation was verified with a relatively complex product. 相似文献
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数字化渐进成形技术是一种新兴的金属板料柔性成形技术。通过有限元数值对其成形过程模拟,能够对渐进成形的研究起理论指导作用。利用有限元分析软件LS-DYNA对金属板料渐进成形的过程进行了模拟。根据试验特点建立了相关的有限元模型,对其中工具头的运动轨迹和加载方式进行了简化,同时根据实际成形特点建立了边界条件和约束,保证了模拟的真实性,并据此模型分析了成形过程中板料上的应力、应变分布特点。 相似文献
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基于数控渐进成形技术进行板科成形工艺研究,提出完整的渐进成形工艺规划,并将其成功应用于车身装饰件成形.对影响成形的主要参数成形工具头直径d和每层进给量△h进行了分析.为今后完善和发展金属板料数控渐进成形技术起到重要作用. 相似文献
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Zemin Fu Jianhua Mo Fei Han Pan Gong 《The International Journal of Advanced Manufacturing Technology》2013,64(9-12):1239-1248
There exists some error between the manufactured part shape and the designed target shape due to springback of this part after forming. To reduce the error, an iterative algorithm of closed-loop control for correcting tool path of the single-point incremental forming, based on Fast Fourier and wavelet transforms, has been developed. Moreover, the data of the springback shapes, after unloading, of the sheet metal parts formed with the trial and corrected tool paths, used for iterative correction of tool path in the algorithm, are obtained with finite element model (FEM) simulation. Then, a truncated pyramid-shaped workpiece, whose average errors are +0.183/?0.175 mm, was made with the corrected tool path after three iterations solved by the above algorithm and simulation data. The results show that the tool path correction algorithm with Fourier and wavelet transforms is reasonable and the means with FEM simulation are effective. It can be taken as a new approach for single-point incremental forming of sheet metal and tool path design. 相似文献
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Zemin Fu Wei Chen Xiuli Tian Bingkun Hu 《The International Journal of Advanced Manufacturing Technology》2014,72(5-8):561-570
Based on Hill’s yielding criterion and plane strain condition, the explicit expressions of elastoplastic constitutive model are derived in this paper which takes into account the effects of transverse stress, neutral surface shifting, and sheet thickness thinning on the sheet springback of air-bending. Then, this model is embedded into ABAQUS software platform by means of programming. Finally, 3D ABAQUS finite-element models (FEM), used to form the semiellipse-shaped workpiece with super length and large opening of sheet metal, are established, and the multiple-step incremental air-bending forming and springback processes are simulated. The simulation and experiment results show that the data predicted with the new constructed constitutive model under the plane strain condition are in much better agreement with experimental data than those predicted with the constitutive model built-in ABAQUS. It can be taken as a valuable mathematical tool used for multiple-step incremental air-bending forming simulation of large area sheet metal. 相似文献
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Zemin Fu Pan Gong 《The International Journal of Advanced Manufacturing Technology》2014,71(1-4):357-364
To solve the springback problem for sheet metal forming, feedback control idea in automatic control theory is introduced to incremental air-bending forming process. The advanced control techniques are used to solve precision forming for workpiece of sheet metal. However, stability, accuracy, and rapidity of closed-loop control can directly affect system normal operation. Aiming to analyze the effect of stability on the quality of the formed workpiece, a closed-loop control system model for incremental air-bending forming is established. The transfer function and characteristic equation of the closed-loop system are solved through theory deduction and minor incremental linearization method. Both simulations with Matlab/Simulink and root locus results show that, as the overall gain is equal to one, the shape of formed part could converge to the target shape at the fastest rate. Finally, a semiellipse-shape workpiece is manufactured with the corrected mold obtained by the closed-loop forming method. The experimental results show that the closed-loop forming way is feasible and the means of correcting the mold parameters by iterative compensation of the stable closed-loop control system is effective. It can be taken as a new approach for sheet metal incremental air-bending forming and mold design. 相似文献