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用三次样条流线条元法分析带材的三维塑性变形,用分割模型影响系数法分析辊系的弹性变形,用BP神经网络方法对轧后带材板形进行模式识别,将三者联立,对900 mm HC轧机冷轧带材轧制过程进行了计算机仿真,得到了较为详细的应力及变形的仿真结果。仿真实例表明,提出的方法和模型符合实际,对三维轧制理论、板形理论及控制技术的发展有重要意义。 相似文献
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STUDYONSTRIPANDROLLDEFORMATIONCOUPLINGOFCOLDSTRIPROLLINGON4HMILL①LiuHongminHuGuodongYanshanUniversityAbstractThecoldstriprol... 相似文献
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模拟板带轧制三维变形的流面条元法 总被引:4,自引:0,他引:4
提出模拟板带轧制过程三维变形的一种新的数值方法——流面条元法。沿着金属的流动轨迹,将变形区划分为若干流面(曲面)条元,为方便分析和计算,又将其映射为平面条元。横向位移和高向位移的纵向分布被分别构造为四次曲线和二次曲线,其横向分布均用三次样条插值函数表示,高向分布均用二次曲线拟合。根据塑性力学流动理论,分析推导了变形区三维变形和应力的数学模型。与曾经提出的流线条元法相比,考虑了应力与变形沿高向的不均匀分布,实现了精确的三维分析和计算。仿真实例表明,该方法和模型符合实际,为板带轧制过程的三维力学仿真提供了一个新的实用工程数值方法。 相似文献
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C. Liu P. Hartley C. E. N. Sturgess G. W. Rowe 《International Journal of Mechanical Sciences》1985,27(7-8)
The rolling of copper strip has been simulated using an elastic-plastic finite-element method (EPFEM) for plane-strain deformation. The use of this program, which includes both material and geometric non-linearities, permits the identification of elastic and plastic deformation in rolling, and also the effects of unloading. The rolling model is based on the physically realistic concept that the strip is drawn into the roll gap by the action of interface friction.The results clearly show the maximum pressure associated with the neutral point and are in good quantitative agreement with earlier work. In addition, the stresses and deformation outside the nominal contact are presented. 相似文献
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带钢平整机轧制压力的计算模型 总被引:1,自引:0,他引:1
平整较厚带材时,变形区水平应力沿板厚不均匀分布对平整轧制压力的计算有着重要影响。在考虑带材入口和出口弹性变形区影响的冷轧轧制压力计算模型的基础上,通过修改弹性变形区入口和出口应力边界条件,提出平整轧制压力计算模型,并对弹性区入口和出口表面水平应力进行了计算。用该模型计算的平整轧制压力与原有计算模型和实测值进行对比,证明模型提高了精度。 相似文献
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Jantzen L. Hinton Arif S. Malik Ramana V. Grandhi 《International Journal of Mechanical Sciences》2011,53(10):827-838
With increased demand for thin gage flat metals, control of strip flatness or shape in cold rolling processes has become very important. To improve the flatness quality of cold rolled metal strip and sheet, this work provides a rapid method to predict the transient strains (or stresses) occurring during the rewinding of flat-rolled steels having problematic asymmetric strip thickness profile (or wedge). Flatness control systems, used to monitor and correct the distribution of stress across the width of rolled sheet, are unable to distinguish between stresses induced during rolling, and those caused when rewinding strip containing asymmetric thickness profile. The winding stresses, unless large enough to plastically deform the strip, vanish upon unwinding during subsequent operations such as stamping. Therefore, to help avoid strip flatness defects in thin strip containing wedge, a method is developed to separate the winding stress contribution from the overall stresses that are measured indirectly by flatness control systems. A fourth-order polynomial Airy function is developed to rapidly predict the in-plane stresses based on mandrel wrap number and spatial location on the strip. The Airy function is obtained by applying two-dimensional finite element analysis to study the transient in-plane stresses during rewinding at various numbers of mandrel wraps for a strip containing wedge profile. Three-dimensional finite element analysis is first employed, however, to show justification to a simplified two-dimensional problem described by the plane-stress Airy function. The two-dimensional finite element analysis provides insight as to how the in-plane stresses evolve, and allows determination of coefficients for the Airy function based upon model geometry and displacement boundary conditions. This approach differs from other methods that employ Fourier series to solve the biharmonic equations for an assumed two-dimensional problem. Finally, filtering of the winding stresses from flatness control system input signals is also discussed based on data taken from a rolling mill different to that used for model development. 相似文献
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The paper presents a predictive model of the flatness defects, which appear during rolling of thin plates, the origin of which is the roll stack thermo-elastic deformation. The combination of the elastic deflection, the thermal crown and the roll grinding crown results in a non-parallel bite, and if the deformed roll transverse profile is not an affinity of the incoming strip profile, differential elongation results and induces high stresses in the outgoing strip. The latter, combined with the imposed strip tension force, result in a net post-bite stress field which may be sufficiently compressive locally to promote buckling. A variety of non-developable shapes may result, generally occurring as waviness (centre waves, wavy edges, quarter-buckles, etc.). This problem is most of the time addressed in a decoupled way, i.e. as a post-processing of the residual stresses computed by a strip rolling model; the present paper on the contrary describes a fully coupled approach of in-bite plastic deformation and post-bite buckling. For this purpose, a simple buckling criterion has been introduced in a FEM model of strip and roll deformation, Lam3/Tec3; its implementation is documented in details. The capabilities and limits of the present approach are described and discussed. Characterised by its coupled approach, it is primarily devoted to cases where on-line (under tension) manifested defects occur. It is shown that the impact of the post-bite, post-buckled stress field on the in-bite stress and strain fields is quite small in the cases investigated; however, subtle changes appear in the velocity field at bite exit, and this is sufficient to transform completely the post-bite stress field, which is found in much better agreement with measurements if such a coupled treatment is used. 相似文献
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Laila S. Bayoumi 《International Journal of Mechanical Sciences》1997,39(4):397-408
In the rolling of wide strip, longitudinal tensile stresses develop along the edges which enhance edge cracking. Theoretical assessment of these stresses and the factors affecting their magnitude and spread are not emphasized in existing solutions, since most of the solutions are based on the assumption of plane strain along the entire width. In the present work a flowline field solution is developed to analyze the flow and stresses in steady state wide strip hot rolling based on the concept of a plane-strain middle zone and two lateral flow edge zones from which edge stresses and edge zones width have been determined. The results obtained show that the maximum value of the longitudinal edge stresses is 1/√3 the flow stress and occurs at the neutral point where the width of edge zone is maximum. The influence of the coefficient of friction at roll-strip interface, roll diameter and thickness reduction ratio on the magnitude and spread of edge stresses is not appreciable. 相似文献
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A new method—the stream surface strip element method (SSSEM)—for simulating the three-dimensional deformations of plate and strip rolling process is proposed. The rolling deformation zone is divided into a number of stream surface (curved surface) strip elements along metal flow traces, and the stream surface strip elements are mapped into the corresponding plane strip elements for analysis and computation. The longitudinal distributions of the lateral displacement and the altitudinal displacement of metal are constructed respectively to be a quartic curve and a quadratic curve, the transverse distributions of them are expressed as the third-power spline function, and the altitudinal distributions of them are fitted to be a quadratic curve. Based on the flow theory of plastic mechanics, the three-dimensional deformations and stresses of the deformation zone are analyzed and formulated. Compared with the streamline strip element method, the SSSEM considers the uneven distributions of stresses and deformations along altitudinal direction, and realizes an accurate three-dimensional analysis and computation. The simulation examples indicate that the method and the model of this paper are in accord with facts, and provide a new reliable engineering-computation method for the three-dimensional mechanics simulation of plate and strip rolling process. 相似文献
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F. D. Fischer F. G. Rammerstorfer N. Friedl W. Wieser 《International Journal of Mechanical Sciences》2000,42(10):1887
The paper deals with analytical and numerical considerations of buckling phenomena in thin plates or strips under in-plane loads which typically appear during rolling and levelling, i.e. straightening by stretching, of sheet metal. Buckling due to self-equilibrating residual stresses, caused by the rolling process, in eventual conjunction with global tensile stresses (denoted as “rolling buckling”) as well as buckling during the levelling process (denoted as “stretching buckling” or “towel buckling”) are considered. Analytical estimates are derived and compared against results of numerical simulations and field observations. Mode jumping by varying the global strip tension is explained on the basis of the derived analytical solutions. It is shown how from the waves, i.e. height and length, observed on the strip sliding over or lying on a rigid plane one can provide information about the distribution of the differences in the plastic strains over the width of the strip which lead to the buckled configuration. And, vice versa, knowledge of the plastic strain distribution can be used for estimating the expected wave heights representing a measure for the geometrical quality of the rolled product. The influence of the dead weight of the strip on the post-buckling pattern is also discussed on the basis of non-linear analyses. 相似文献
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S. Domanti D. S. McElwain R. H. Middleton W. J. Edwards 《International Journal of Mechanical Sciences》1993,35(11)
Current simulation models for the prediction of residual stresses in flat metal rolling utilize heuristic assumptions about the roll-gap entrance and exit velocity distributions. The nature of the velocity distributions which occur in the strip adjoining the roll-gap is investigated. The problem is formulated in terms of velocity perturbations and the resulting nonlinear equations are approximated by a linear set of equations. The method of solution uses either the stress function or its integral to allow mixed boundary conditions of velocities and/or stresses at the elastic boundaries. The resulting semi-infinite problem is solved using a Laplace transform technique. Two examples are provided to illustrate the velocity and stress distribution behaviour in a moving elastic strip. 相似文献
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Lee Sang-Ho Song Gil-Ho Lee Sung-Jin Kim Byung-Min 《Journal of Mechanical Science and Technology》2011,25(8):2101-2109
The quality requirements for thickness accuracy in cold rolling continue to become more stringent. In cold rolling mill, it
is very important that the rolling force calculation considers rolling conditions. The rolled strip thickness was predicted
using calculated rolling force. However, the prediction of strip thickness in cold rolling is very difficult; in particular,
for 6-high mill with shifted intermediate roll (IMR), the accuracy of thickness is not good. In this study, to improve the
accuracy of rolled strip thickness, the roll gap flattening can be given based on Hertz contact theory, with contact between
rolls and the smooth cylindrical rolls for the rolling elastic deformation. Also, the distribution of the roll gap flattening
may be calculated using the contact force of unit transverse length. The strip profile at the continuous cold rolling is calculated
by using the numerical analysis model considering the initial strip profile before cold rolling. Hence, we propose that the
numerical model can predict the rolled strip profile more quickly and accurately and be applicable to the field. The results
of the proposed numerical model were verified by FE-simulation and cold rolling experiments of 6-high mill with five stands. 相似文献
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As the traditional forging process has many problems such as low efficiency, high consumption of material and energy, large cylindrical shell rolling is introduced. Large cylindrical shell rolling is a... 相似文献
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板形标准曲线的理论计算方法 总被引:11,自引:3,他引:8
联立板形预报模型和板形判别模型,提出板带轧机板形标准曲线的理论计算方法。该理论计算方法的思路和原则是最大限度地消除板凸度并同时兼顾板形良好,最终使板形趋于最好,这种计算方法的目标是实现板形和板凸度的综合最优控制。以1 220 mm五机架带钢冷连轧机和900 mm单机架带钢冷轧机5道次轧制为例,分别对轧制中凸板和中凹板的情况进行计算,计算结果证实了理论分析计算的正确性。这种板形标准曲线的理论计算方法为进一步从理论上定量研究板形标准曲线模型奠定了良好的理论基础。 相似文献
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An experimental and numerical study of cold rolling lubricated by O/W emulsion has been carried out. The strip rolling experiment
was carried out on a Hille experimental rolling mill with a view to study the performance of emulsion lubrication in terms
of practical rolling parameters. Accordingly, rolling parameters such as rolling force and torque were measured. The experimental
measurements compare favourably with the computed results from a numerical scheme developed by the authors. The scheme, based
on a two-phase lubricant model, is capable of calculating the oil concentration at any point within the inlet zone and work
zone, rolling pressure, film thickness, and fractional contact area ratio associated with strip rolling under mixed film lubrication
at different rolling speeds. Using this scheme, the intertwined effects of an emulsion’s parameters such as: oil concentration,
mean oil droplet size, and rolling speed on strip rolling were investigated. The numerical study encompassed the mixed film
regime for speed, S ranges from 10−4 to 10−2, supply oil concentration level λds from 1 to 10%, and oil droplet size D
S from 5 to 10. Experimentally, the differences between water, oil and emulsion-lubricated rolling are not discernible except
for film thickness. At a low speed of 10 RPM, force and torque of water-lubricated rolling are marginally higher than oil-
or emulsion-lubricated ones. However, the difference between emulsion and neat oil is not apparent. The numerical results
show the occurrence of a moderate oil concentration increase in the inlet zone followed by a sharp one at the beginning of
the work zone. The effect of the concentration process is predominantly seen in the film thickness and the lubricant pressure
whilst its effect on the total pressure is less pronounced. The analysis of the results suggests that it is possible to lower
the emulsion oil concentration without any adverse effect on the rolling process. This principle can be used to control the
outlet lubricant film thickness and hence the surface quality of the rolled strip. 相似文献
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通过热模拟机Gleeble-1500对Q215热轧窄带钢在不同的轧后冷却速度下进行了模拟,研究了冷却速度对热轧窄带钢组织性能的影响.根据现场条件,得到了合理的冷速范围.同时,采用MARC对其冷却过程进行有限元数值模拟,分析了冷却速度对钢带温度场分布的影响.对提高产品的强度及韧性,使其适应以后的冷轧工艺提供了帮助. 相似文献