共查询到20条相似文献,搜索用时 15 毫秒
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The deformation mechanism of incremental sheet forming (ISF) is examined experimentally through forming specially prepared copper sheets. Strain distributions through the thickness of the sheets are measured for two configurations of ISF: two-point incremental forming (TPIF) and single-point incremental forming (SPIF), and a comparison is made to pressing. The measurements show that the deformation mechanisms of both SPIF and TPIF are stretching and shear in the plane perpendicular to the tool direction, with shear in the plane parallel to the tool direction. Strain components increase on successive laps, and the most significant component of strain is shear parallel to the tool direction. Increasing stretching and shear perpendicular to the tool direction account for differences between the sine law prediction and measured wall thickness for both SPIF and TPIF. The observed mechanisms of SPIF and TPIF differ from a mechanism of pure shear that has previously been assumed. 相似文献
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A. G?ttmann J. Diettrich G. Bergweiler M. Bambach G. Hirt P. Loosen R. Poprawe 《Production Engineering》2011,5(3):263-271
Asymmetric Incremental Sheet Forming (AISF) is a relatively new manufacturing process. In AISF, a CNC driven forming tool
imposes a localized plastic deformation as it moves along the contour of the desired part. Thus, the final shape is obtained
by a sequence of localized plastic deformations. AISF is suitable for small series production of sheet metal parts as needed
in aeronautical and medical applications. Two main process limits restrict the range of application of AISF in these fields.
These are the low geometrical accuracy of parts made from titanium alloys or high strength steels and, for titanium alloys,
the limited formability at room temperature. In this paper a new concept for laser-assisted AISF is introduced including the
required components. Furthermore, the CAX tools used for programming the NC path for the forming tool and the laser spot are
illustrated. First experimental results show that the formability of the alloy Ti Grade 5 (TiAl6V4), which is usually used
in aeronautic applications, can be increased. 相似文献
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《CIRP Annals》2019,68(1):317-320
Limited geometric accuracy in incremental sheet forming is a major obstacle for its wide adoption in industry. This paper develops a generic methodology, suitable for arbitrary part geometries and various ISF processes, for addressing one of the main causes of geometric inaccuracy, i.e., in-process springback. The methodology consists of three main elements: determination of key control points to treat geometric complexity, simplified simulation models to predict springback offline, and in-situ toolpath modification during forming. It is shown experimentally that the method provides an efficient and robust solution for various geometries with negligible setup cost. 相似文献
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Tooling concepts to speed up incremental sheet forming 总被引:1,自引:1,他引:0
A major drawback of asymmetric incremental sheet forming (AISF) is the long cycle time. AISF is known in general as forming
of a sheet metal by only one small forming zone. The developed concepts presented in this paper aim at decreasing the main
process time by applying several forming zones on the part through multiple tools working in parallel. By the use of a systematic
design process, four major structural tooling concepts were invented. Those variants were compared to each other by a cost-utility
analysis. As a result, a prototype with two tools was produced to fasten the AISF process. 相似文献
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通过聚丙烯(PP)高分子板材的多道次渐进成形实验,研究多道次渐进成形零件的材料流动、应变及壁厚分布状况。研究结果表明,PP板多道次渐进成形的第一、第二主应变随成形深度的增大而呈上升趋势,且壁厚随着成形深度的增大而明显减小,无法成形深度过大的零件。通过实验数据,分析零件壁厚变化的原因,指出因道次间角度差的存在产生的成形台阶是导致零件底部下沉和壁厚骤减的原因。此外,针对壁厚问题,提出影响零件成形质量的因素,并结合实验验证,得出结论:增加道次次数、采用圆弧轨迹和减小道次间角度差可以在不同程度上改善壁厚分布状况。 相似文献
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板料渐进成形技术作为柔性制造技术,其研究已经取得相当进展。但是在进给轨迹连续的普通渐进成形中,材料在成形过程容易产生沿轨迹方向的推挤,而产生不必要的变形,影响加工能力和加工质量。通过圆弧沟槽实验,对比点压渐进成形和连续渐进成形,发现点压渐进成形可获得的沟槽长度为60.5 mm,大于连续渐进成形中48.9 mm的沟槽长度;破裂位置最大主应变分别为1.212和0.982,说明板料点压渐进成形时的成形性能比连续渐进成形好。通过改变点压渐进成形中正弦波的波长和振幅,说明两参数对成形性能的影响。采用成形性能更好的点压渐进成形,可减少多道次渐进成形的成形道次,拓展渐进成形所能成形的零件结构类型。 相似文献
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S. Dejardin S. Thibaud J.C. Gelin G. Michel 《Journal of Materials Processing Technology》2010,210(2):363-369
The paper is related to the analysis of shape distortions and springback effects arising in single point incremental sheet forming in order to study the use of a FE model based on shell elements to perform simulation of the process. A comparison between numerical and experimental results is made to assess the suitability of the model. The measurements of geometrical profile of a truncated cone and springback of cut rings show that the FE model allows to predict accurate results for a set of well defined process parameters. The deformation mechanism of ISF is taken into consideration to determine the limits of the model studied. 相似文献
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Fundamental studies on the incremental sheet metal forming technique 总被引:17,自引:0,他引:17
The idea of incremental forming technique has been investigated for production of sheet metal components. With this technique, the forming limit curve (FLC) appears in a different pattern, revealing an enhanced formability, compared to conventional forming techniques. In the present study, the formability of an aluminum sheet under various forming conditions was assessed and difficult-to-form shapes were produced with the technique. By utilizing knowledge and experience obtained during the present study, it became possible to produce some free surfaces. 相似文献
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成形极限图是判断板料成形中是否会发生失效的重要依据。渐进成形中的板料成形极限图和传统冲压成形极限图有显著不同。板料传统冲压成形极限图测试方法已较为完善,而对于渐进成形尚没有形成统一的标准。本文在已有的测试方法基础上,提出了通过渐进成形圆弧沟槽、十字交叉圆弧沟槽直至板料端部破裂后,测量破裂位置最大和最小主应变以获得板料渐进成形极限图的新方法。通过数值模拟研究,分析了采用该方法对板料进行渐进成形时板料局部的应变状态,表明该方法可行;并使用该方法得了0.9mm厚工业纯铝1060板料的渐进成形极限图。 相似文献
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板料直壁零件数控渐进成形 总被引:1,自引:0,他引:1
板料直壁零件成形是渐进成形的难点之一。为了成形直壁零件,一般采用多次成形的方法。文章对直壁零件多次成形法从理论上进行了分析,并且通过实验,验证了这种方法的正确性。 相似文献
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In incremental sheet forming (ISF) strains can be obtained well above the forming limit curve (FLC) that is applicable to common sheet forming operations like deep drawing and stretching. This paper presents an overview of mechanisms that have been suggested to explain the enhanced formability. The difference between fracture limit and necking limit in sheet metal forming is discussed. The necking limit represents a localized geometrical instability. Localized deformation is an essential characteristic of ISF and proposed mechanisms should stabilize the localization before it leads to fracture. In literature six mechanisms are mentioned in relation to ISF: contact stress; bending-under-tension; shear; cyclic straining; geometrical inability to grow and hydrostatic stress. The first three are able to localize deformation and all but the last, are found to be able to postpone unstable growth of a neck. Hydrostatic pressure may influence the final failure, but cannot explain stability above the FLC. 相似文献
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Fei HAN Jian-hua MO Hong-wei QI Rui-fen LONG Xiao-hui CUI Zhong-wei LI 《中国有色金属学会会刊》2013,23(4):1061-1071
In the incremental sheet forming (ISF) process, springback is a very important factor that affects the quality of parts. Predicting and controlling springback accurately is essential for the design of the toolpath for ISF. A three-dimensional elasto-plastic finite element model (FEM) was developed to simulate the process and the simulated results were compared with those from the experiment. The springback angle was found to be in accordance with the experimental result, proving the FEM to be effective. A coupled artificial neural networks (ANN) and finite element method technique was developed to simulate and predict springback responses to changes in the processing parameters. A particle swarm optimization (PSO) algorithm was used to optimize the weights and thresholds of the neural network model. The neural network was trained using available FEM simulation data. The results showed that a more accurate prediction of springback can be acquired using the FEM-PSONN model. 相似文献