共查询到18条相似文献,搜索用时 375 毫秒
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双沟球轴承外圈冷辗扩数值模拟与试验研究 总被引:1,自引:0,他引:1
毛坯尺寸和芯辊进给速度是环件冷辗扩工艺参数研究的重要内容,通过对一组毛坯和芯辊进给速度进行模拟优化,分析比较了不同宽径比和进给速度对辗扩力及辗扩力矩的影响,得出了最优参数,并采用优化参数进行试验,得到了合格的双沟球轴承外圈产品。 相似文献
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混合硬化弹塑性本构关系及其在环件冷辗扩模拟中的应用 总被引:4,自引:1,他引:4
采用数值模拟方法和混合硬化弹塑性本构关系,提出了基于弹性张量的应力补偿更新算法,引入等向强化系数,给出了有限元计算步骤,基于ABAQUS/Explicit平台开发了子程序VUMAT,并在单个单元模型中验证了其可靠性。将其应用于环件冷辗扩过程模拟中,着重研究了等向强化系数对环件冷辗扩成形的影响规律。结果表明,随着等向强化系数的增大,辗扩力、辗扩力矩增大,鱼尾形状系数减小,环件外圈金属受各向异性硬化影响较大,进而从理论上进行了解释。研究结论指出该研究对环件冷辗扩成形工艺具有指导意义。 相似文献
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环件冷辗扩芯辊进给速度规范设计 总被引:8,自引:0,他引:8
针对环件冷辗扩的特点,结合环件冷辗扩机的工作原理,提出了四种不同的芯辊进给速度设计规范。以矩形截面为分析对象,根据进给速度为常数、每转进给量为常数、环件外径增长速度为常数和随动导向辊圆心的旋转速度为常数这四种控制条件,提出了芯辊进给速度设计方法,推导出了直径的增长规律。根据试验数据,以Abaqus为平台,模拟了四种进给速度规范下的辗扩过程,分析了冷辗扩力和环件成形的圆度变化规律。总结了四种设计方案的优缺点,提出了在不同辗扩阶段采用不同的进给规范的设计思路,以期能为环件冷辗扩的工艺和控制设计提供新的理论依据。 相似文献
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为了定量预报二次冷轧过程轧制变形区油膜厚度,结合二次冷轧机组乳化液直喷系统的设备与工艺特点,分析了带钢表面析出油膜、工作辊表面附着油膜的形成机理,建立了一套二次冷轧过程轧制变形区带钢上下表面油膜厚度模型,定量分析了乳化液流量密度、乳化液浓度、乳化液析出距离、轧机入口轧制速度、轧制咬入角、带钢入口变形抗力、后张力、轧制油初始动力黏度、轧制油压力黏度系数对轧制变形区带钢上下表面油膜厚度的影响,并将该模型应用到某1220二次冷轧机组的生产实践,编制出了相应的模型计算软件,实现了二次冷轧过程变形区油膜厚度的预报,为二次冷轧过程润滑性能的控制奠定了理论基础。 相似文献
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Lanyun Li He Yang Lianggang Guo Zhichao Sun 《Journal of Mechanical Science and Technology》2007,21(10):1541-1547
Cold ring rolling is a much complex physical process with multi-factors. Two forming parameters, the feed rate of mandrel
and the rotational speed of main roll, affect the quality of deformed ring significantly and the feed amount per revolution
of ring in the form of their ratio. By their ratio, the interactive effects of the two forming parameters on the T-shaped
cold ring rolling process are explored through 3D-FEM in Abaqus software. The results show: firstly the study objects (roll
force, growth rate of diameter, degree of inhomogeneous deformation, filling capability of groove, average side spread and
fishtail coefficient) are almost invariable if the two parameters are increased (or decreased) proportionally; secondly whether
the ratio is changed by the feed rate of mandrel or by the rotational speed of main roll, the variation of each study object
with the ratio is approximately the same; thirdly the increase of the ratio is beneficial to the growth of diameter and the
restrictions of inhomogeneous deformation, average side spread and fishtail coefficient, but it causes the roll force to increase
and the filling capability of groove to decrease. 相似文献
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GH4169高温合金薄壁钻孔与常规的高温合金厚壁钻孔相比有其特殊性,应用有限元分析软件对硬质合金钻头钻削镍基高温合金平板薄壁件的动态过程进行建模,总结钻削过程中钻削力的变化特点以及进给量和钻削速度对钻削力的影响。研究结果表明:当钻尖高度大于薄壁件厚度时,根据钻头与薄壁件的相对位置,可将钻削过程分为三个阶段,在不同阶段钻削力变化特点不同;轴向力和扭矩随着钻削速度的增加而增加,但轴向力增加幅度不大;轴向力和扭矩均随着进给量的增大而明显增大;进给量对钻削力和扭矩的影响较钻削速度明显。 相似文献
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J. B. Hawkyard W. Johnson J. Kirkland E. Appleton 《International Journal of Mechanical Sciences》1973,15(11):873-893
Analyses are developed for predicting roll force and torque during ring rolling between plain cylindrical rolls. A nomograph is given to allow easy application of the theory. Conventional analyses for flat rolling are not generally appropriate to ring rolling, whereas the present theory considers the particular roll geometry and rolling conditions encountered in the process.Measurements of roll force and torque, taken during ring rolling experiments, are shown to be in good agreement with the theoretical predictions. The experiments are carried out on a new experimental mill having a mandrel which retracts axially for loading and unloading the ring, and is symmetrically supported between roller bearings within a four-column frame during rolling. This arrangement is believed to offer certain advantages over most commercial machines. 相似文献
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A complete mathematical model of the Variable Gap flat-Rolling (VGR) process for producing components with variable thickness under hot working conditions is presented. The model is composed of separate submodels for deformation, flow stress, roll force and temperature. Sub-modelling approach allows changes and new developments to be easily incorporated. A three-dimensional deformation analysis of the workpiece based on the upper bound theorem is carried out. A simple velocity field is proposed. To preserve the theoretical consistency, an equivalent coefficient of friction is adopted for roll force calculation. Furthermore, the basic assumption of rigid perfectly-plastic material is modified by introducing the concept of isotropic rate-dependency. Satisfactory results were obtained in spread, torque and force prediction. 相似文献
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Laila S. Bayoumi 《International Journal of Mechanical Sciences》2003,45(3):553-565
Analytical expressions for the roll-pass geometry, velocity, strain, strain rate and stress components are obtained for steady-state tube stretch-reducing hot rolling. From these expressions the reduction in tube diameter and wall thickness, inter-stand tensions, roll load and rolling torque have been determined in relation to the roll gap opening and the inter-stand velocity increase ratio. The results have shown that increasing the interstand velocity increase ratio will increase the inter-stand tension while the roll load remains almost unchanged. The rolling torque increases with the increase of the back inter-stand velocity increase ratio and decreases with the increase of the ratio at the front. There is a limiting value for the inter-stand velocity increase ratio at which the rolling process will tend to become unstable. The analysis has been validated by comparing the theoretical results with on-line power measurements on an industrial tube stretch-reducing hot rolling mill. 相似文献
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An upper bound method for analysis of three-dimensional deformation in the flat rolling of bars 总被引:1,自引:0,他引:1
A new upper bound method for the analysis of three-dimensional deformation in the flat rolling of bars is proposed. In the conventional upper bound method, stress distribution is not calculated. Hence, a new method of calculating stress distribution is proposed in which the hydrostatic stress in each element and the contact stress on the contact surface between material and roll in each element are calculated. In the conventional upper bound method, the structure of the computer program also depends highly on the kinematically admissible velocity fields assumed. Hence, a new method of analysis in which the structure of the computer program depends minimally on the kinematically admissible velocity fields assumed is proposed. In the analysis of strip rolling, the calculated roll force and roll torque agree with the roll force and roll torque calculated from Sims’ slab method. In the analysis of the flat rolling of bars, the calculated width spread agrees with the width spread obtained by experiments reported in the literature. The effects of a reduction in thickness, roll radius, material width-to-height ratio, front tension, back tension, and front and back tensions on the width spread, forward slip, roll force and roll torque are demonstrated. Hence, the validity of the new upper bound method is confirmed. 相似文献
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Laila S. Bayoumi 《International Journal of Mechanical Sciences》2001,43(11):770
An analytical solution is obtained for the problem of cold drawing through flat idle rolls of regular polygonal metal tubular sections from round tube. The solution is based on obtaining a compatible velocity field that satisfies kinematic conditions to yield the strain-rate components. The stresses are obtained by combining the material constitutive law with Levy–Mises flow rule and integrating the equations of equilibrium. The solution is applied to the case of a low-carbon steel standard round pipe to investigate the effects of drawn section shape, friction at the roll interface, roll radius and wall thickness on the roll load and drawing force. The results obtained have shown that for different section shapes the roll load and drawing force decrease with the increase of the number of sides and increase with the decrease of corners radius. Surface friction has no appreciable effect on the loads which allows dry drawing. An increase in the roll radius increases the roll load but the drawing force remains unchanged. Increasing the wall thickness does not proportionally increase the roll load and drawing force; the tube wall behaves as a thin shell subjected to biaxial combined membrane and bending stresses. 相似文献