共查询到20条相似文献,搜索用时 15 毫秒
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R. Ibrahim S. Golovashchenko L. M. Smith A. Mamutov J. Bonnen A. Gillard 《Journal of Materials Engineering and Performance》2014,23(5):1759-1769
During high-speed sheet metal forming processes, the speed at which the work piece contacts the die tooling is on the order of hundreds of meters per second. When the impact is concentrated over a small contact area, the resulting contact stress can compromise the structural integrity of the die tooling. Therefore, it is not only important to model the behavior of the workpiece during the high-speed sheet metal forming process, but also important to predict accurately the associated workpiece/tooling interface loads so that engineers can more confidently propose robust die tooling designs. The foundation to accurate predictions of contact stress on die tooling is a reliable contact model within the context of a finite element simulation. In literature, however, there exists no comprehensive guideline for establishing a contact model for high-speed sheet metal forming processes using the finite element method. In this paper, mathematically justified contact model recommendations are offered for the electrohydraulic forming (EHF) process. 相似文献
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《Journal of Materials Processing Technology》2000,97(1-3):44-53
Friction and slip between the workpiece and the tool in metal forming processes are important issues in tool design and product development. This paper characterizes the tool–workpiece interfacial slip in a flat-wedge cross-wedge rolling process (CWR) using an explicit dynamic finite element method. An experimentally validated finite-element model of CWR is used to investigate the effects of the friction coefficient, the forming angle, and the area reduction on the tool–workpiece interfacial slip. A total of 14 rolling conditions are analyzed. An analytical CWR model for the workpiece rotational condition, which predicts the onset of rotation, is derived. Using this model, the critical area reduction and friction coefficient are compared with the failure conditions that occurred in the finite-element modeling and the prototype experiments. The variation of interfacial slip with CWR design parameters is found to provide insight regarding the CWR process design. 相似文献
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This study develops new model that is suitable for predicting the surface topography of the products of lubricated sheet metal forming. In the lubrication analysis, a finite element model is derived for the average Reynolds equation, no matter whether the tooling surface comes into contact with workpeice surface or not. With regard to the asperity contact theory and surface parameter analysis, a novel model takes account of the smoothing, roughening and tool elastic microwedge effects on the surface of the workpiece. A model was combined with a finite element membrane code of axisymmetric stretch forming to predict the contact area ratio and the surface roughness. Numerical results revealed that the new model is consistent with the experimental results. The superiority of the new model over the conventional model is that it predicts the surface roughness more accurately during the lubricated sheet metal forming process. 相似文献
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R.X. Gao 《CIRP Annals》2010,59(1):399-402
A new method is proposed for determining the contact pressure distribution (CPD) between the tool and the workpiece in sheet metal forming processes. Contact pressure is measured at discrete points at the tool-workpiece interface by sensors that are structurally embedded beneath the tooling surface. An analytical framework is developed for determining the pressure values between the sensing points through the construction of continuous CPD maps. This is achieved using the Thin Plate Spline (TPS) surface generation method, which creates temporal snapshots of the CPD during a forming process. The effectiveness of this technique is illustrated for a panel stamping operation. 相似文献
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花键冷滚压精密成形力学分析与数值模拟 总被引:1,自引:0,他引:1
分析了花键冷滚压成形过程,对冷滚压精密成形过程的单位平均压力、冷滚压接触面积和滚压力进行了分析与计算.在此基础上,建立了花键冷滚压过程的力学模型与数学模型,并对花键冷滚压成形过程进行了数值模拟.通过对理论分析、数值模拟和试验研究的对比分析,为花键冷滚压成形工艺的研究与应用提供了理论依据. 相似文献
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利用MSC-Marc有限元分析软件,建立了BT20合金筒形件真空热胀形的热力耦合有限元模型。在优化模型中引用了步长自适应控制技术和两步法模拟。计算了BT20合金筒形件真空热胀形过程的温度场和变形场。结果表明:采用步长自适应控制技术和两步法模拟,有效的缩短了模拟时间,在精度变化不大的情况下,显著提高运算效率。计算结果与实验结果吻合较好。 相似文献
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采用有限元软件DEFORM-3D对楔横轧厚壁空心轴进行热力耦合数值模拟,得到了工艺参数对楔横轧厚壁空心轴不圆度的影响规律。结果表明,在成形角35°~45°、展宽角4°~7°、断面收缩率35%~65%、轧制温度900℃~1100℃时,轧件不圆度与成形角及断面收缩率的变化成反比,与展宽角及轧制温度变化成正比。采用H630楔横轧机进行轧制实验验证了有限元模型的正确性。模拟与实验结果证明,轧件横截面失圆是楔横轧成形厚壁空心轴类件常见的质量问题;变形区金属沿轴向的流动受到未变形金属的阻碍,是造成不圆度在轧件的对称面上最大并沿轴向逐渐减小的原因。研究结果为确定楔横轧厚壁空心轴的工艺参数提供了理论依据。 相似文献
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多点“三明治”成形是一种针对小批量多曲率板材工件制造而提出的新成形方法。用该方法成形时,上模采用聚氨酯模具,下模为型面可调节的多点模具。为了使多点模具型面连续化和消除工件表面的压痕,在成形过程中使用了金属护板和弹性垫板。由于工件板材两侧都和聚氨酯相接触,因此成形后工件的表面质量好。为了研究采用多点“三明治”成形复杂三维曲面工件的成形过程以及成形可能会出现的表面缺陷,文章选用马鞍面作为目标形面进行了实验研究,提出了用于提高工件的贴模程度,通过改变上模形状的分步成形方法,并得到了Q235B板材厚度和可成形马鞍形工件深度之间的关系曲线。 相似文献
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Jiann-Cherng Su Keith A. Young Shesh Srivatsa John B. Morehouse Steven Y. Liang 《Production Engineering》2013,7(4):391-400
The surface integrity of machined components is defined by several characteristics, of which residual stress is extremely important. Residual stress is known to have an effect on critical mechanical properties such as fatigue life, corrosion cracking resistance, and dimensional tolerance of machined components. Among the factors that affect residual stress in machined parts are cutting parameters and tool geometry. This paper presents a method of modeling residual stress for hone-edge cutting tools in turning. The model utilizes analytical cutting force models in conjunction with an approximate algorithm for elastic–plastic rolling/sliding contact. Oxley’s cutting force model is coupled with a slip line model proposed by Waldorf to estimate the cutting forces, which are in turn used to estimate the stress distribution between the tool and the workpiece. A rolling/sliding contact model, which captures kinematic hardening, is used to predict the machining residual stresses. Additionally, a moving heat source model is applied to determine the temperature rise in the workpiece due to the cutting forces. The model predictions are compared with experimental data for the turning of AISI 52100. Force predictions compare well with experimental results. Similarly, the predicted residual stress distributions correlate well with the measured residual stresses in terms of magnitude of stresses and depth of penetration. 相似文献
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Laser forming of sheet metal offers the advantages of requiring no hard tooling, no spring back and no external force, thus this technology reduces cost, increases flexibility and accuracy. Laser forming is a complicated and transient thermo-mechanical process involving elastic and plastic strain depended on time history. How to control and enhance the accuracy of the laser forming attracts much attention. This paper delivered a deep insight into the mechanism of the edge effects in laser forming, improved an existing analytical model to approximately predict the edge effects, and based on this model a new strategy was put forward to reduce the edge effects. Numerical simulations and experiments were carried out to validate the model and the presented strategy. 相似文献
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F. Capece Minutolo M. Durante F. Lambiase A. Langella 《Journal of Materials Engineering and Performance》2005,14(3):373-377
Sequence design for shape-rolling processes consists of roll pass and profile design, i.e., transforming the billet into a
final shape. For the prediction of the mean effective strain of the workpiece during rod rolling, an analytical model by Shinokura
and Takai was used. They verified the formula by applying it to a variety of rod-rolling geometries (oval-square, oval-round,
square diamond, and diamond-diamond). Today, on the other hand, the finite element (FE) techniques allow analysis of rolling
processes in such a way as to simplify the work of design engineers. In this study, a round-oval pass and a round-flat oval
pass are analyzed for steel rod rolling. In particular, the analysis of the spread, the surface profile, and cross-sectional
area of the workpiece were conducted during rolling. Experimental data such as the maximum spread and the radius are compared
with the results of the analytical model and FE analysis. 相似文献
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F. Capece Minutolo M. Durante L. Giorleo A. Langella 《Journal of Materials Engineering and Performance》2005,14(3):378-382
In the design of roll stands for use in grooved steel rod rolling, the contact pressure between the rolls and the incoming
workpiece is very important. This value can be estimated with the help of a number of analytical and semiempirical models
described in the published scientific and technical literature. In this study, the possibility of using numerical simulation
in determining the contact pressure during the rolling of a round bar with oval grooves is analyzed. The results of the numerical
analyses are then compared with those of two other modified analytical models. 相似文献
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用楔横轧机轧制齿轮轴上的齿形时,对影响齿形成形的各种因素进行分析是提高齿形成形质量的关键。基于图像测量原理对齿形进行特征提取,获得齿形离散数据,然后运用数值计算方法最小二乘法把齿形离散数据拟合成齿形曲线,求解出基圆圆心,绘制出齿形。通过数学建模和实验,分析了模具齿形、齿坯相对模具的位置、坯料的初始形状以及轧制温度对成形齿形的影响。结果表明:模具齿形决定轧制成形的齿形,它们的齿廓是一对共轭曲线的关系;坯料相对模具的位置决定齿形的正负变位状态;通过改变坯料的初始形状可以补偿端面附近齿形下凹的成形缺陷;降低轧制温度可以减弱齿顶"拉尖"现象。 相似文献
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Advances in fabricating superplastically formed and diffusion bonded components for aerospace structures 总被引:1,自引:0,他引:1
Larry D. Hefti 《Journal of Materials Engineering and Performance》2004,13(6):678-682
Superplastic forming and diffusion bonding (SPF/DB) production hardware is being fabricated today for aerospace applications.
Metal tooling is being used to bring the titanium sheets into contact so diffusion bonding can occur. However, due to material
sheet and tooling tolerances, good bond quality is difficult to achieve over large areas. A better method for achieving DB
is to use “stop-off” inside sealed sheets of titanium, which constitutes a pack, and then the pack is bonded using external
gas pressure. A good method for heating the pack for this process is to use induction heating. Components using “stop-off”
that were diffusion bonded first and then superplastically formed have shown much better bond quality than components that
were produced using matched metal tooling. This type of tooling has been successful at bonding small areas as long as the
exerted pressure is concentrated on the area where bonding is required. Finite element modeling is providing weight effect
solutions for titanium SPF/DB aerospace structures.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献