轧环机进给速度设计

环件轧制是轴承、齿轮、法兰、轮箍等环形零件或毛坯的重要生产工序,在机械、汽车、航空等工业中得到了广泛应用。环件轧制原理如图所示,驱动辊同时作旋转轧制运动和直线进给运动,芯辊和导向辊为轴线固定的空转辊,可通过接触摩擦随环件一起转动;轧制时由于驱动辊的作用,环件不断地咬入驱动辊与芯辊构成的轧制孔型或辊缝,产生壁厚减小直径扩大的塑性变形,最终成为具有一定壁厚和直径的环件制品。环件轧制中,轧辊     

双沟球轴承外圈冷辗扩数值模拟与试验研究

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。     

环件径轴向轧制过程锥辊旋转运动学分析

稳定轧制是环件径轴向轧制过程保证产品质量的重要条件之一.文中基于几何关系和运动学原理,对环件径轴向轧制过程中锥辊与环件接触区旋转运动进行了研究,结果表明:轴向锥辊在与环件接触面处的旋转线速度尽量保持一致非常关键,轧制过程中应尽可能地保证锥辊锥顶点位于环件的圆心处.锥辊转速大于环件转速时,应增大径向孔型中的轧制力矩,使环件重新稳定;锥辊转速小于环件转速时,会导致轧制无法正常进行,出现环件位置严重偏移或卡环等现象.     

精密冷轧环机工艺动力学模型

采用交流伺服电机和机械驱动进给系统的冷轧环机,其进给伺服控制系统的设计需要一个新的工艺动力学模型。给出了交流永磁同步伺服电机的数学模型,建立了机械传动机构的等效动力学模型,分析了环件冷辗扩的运动学和变形力学条件,得到了整个进给系统的工艺动力学模型。模型表达了伺服电动机电流、转矩、转速与轧制载荷、芯辊进给速度和位置,以及环件几何尺寸之间的动态关系,各变量之间存在非线性和耦合。模型已用于冷轧环工艺控制器的设计。     

高颈法兰封闭轧制的数值模拟研究

基于DEFORM有限元软件建立了高颈法兰封闭轧制过程的仿真模型,对整个周期的动态轧制过程进行数值模拟分析,分别分析了驱动辊转速、芯辊进给速度对轧制过程以及轧制力的影响规律,并获得了工艺参数的优化指标。研究结果表明,计算机数值模拟对优化工艺参数、提高轧制效率具有重要的意义。     

铝合金薄壁异形截面辗扩成形宏微观模拟

环件轧制作为一种无缝环筒类构件先进塑性成形技术,目前还难以实现铝合金薄壁带筋锥筒构件的近净成形制造.针对2A14铝合金薄壁异形截面环件,建立其辗扩成形宏微观耦合分析有限元模型,选用矩形截面环件作为坯料,基于有限元模拟获得了优化后的轧制孔型,并探究坯料初始温度及芯辊进给速度对材料成形性和微观组织演变的影响规律,得到微观组织均匀且孔型填充性良好的辗环工艺参数.环坯温度为470℃,芯辊进给速度为1.2mm/s,主辊旋转转速为30 r/min,上锥辊的压下速度为0.6 mm/s为最优工艺参数,能够满足2A14铝合金异形截面辗扩形/性控制要求,可为实际生产提供理论指导.     

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

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。     

高颈法兰封闭轧制成形规律的有限元模拟研究

基于DEFORM－3D有限元软件对高颈法兰的轧制成形进行有限元模拟,在环件轧制理论的基础上对高颈法兰的尺寸参数及工艺参数进行设计,阐述了芯辊进给速度和驱动辊转速对力能参数的影响,并给出了合理的取值范围,分析了工艺参数对台阶面展宽量的影响,确定了最佳工艺参数,研究结果对高颈法兰封闭轧制成形的工艺参数设计提供了参考。     

环件轧制原理和设计方法

分析了环件轧制变形特点，提出了环件轧制咬入、锻透和弯曲力学模型，建立了环件轧制咬入条件、锻透条件和刚度条件，阐明了环件轧制原理。基于环件轧制原理，建立了环件轧制技术设计方法，导出了轧制用毛坯。孔型和轧制进给参数设计计算公式。根据环件轧制试验结果，对其咬入条件和锻透条件进行了验证。     

环件冷辗扩芯辊进给速度规范设计

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。     

Research on interactive influences of parameters on T-shaped cold ring rolling by 3d-FE numerical simulation

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.     

GH4169高温合金薄壁钻削加工钻削力的仿真研究

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。     

Analyses for roll force and torque in ring rolling, with some supporting experiments

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.     

花键冷滚压成形力测试与分析

根据花键冷滚压加工原理,按机床受力,将加工过程中的滚压力分为主轴转矩和径向进给力两部分。设计测试方案,用计算机数据采集系统测得了主轴转矩和径向进给力在滚压过程中的实时变化曲线,分析了它们的变化特征,得出压入阶段结束时滚压力取最大值。对不同的工艺参数进行实验,得到了工艺参数对最大滚压力的影响规律。     

Modelling hot flat-rolling of components having curved profiles-part I. Deformation analysis

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.     

Analysis of flow and stresses in a tube stretch-reducing hot rolling schedule

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.     

An upper bound method for analysis of three-dimensional deformation in the flat rolling of bars

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.     

Three dimensional thermal mechanical coupled simulation during hot rolling of aluminium alloy 3003

Rolling passes of a pass schedule supplied by an aluminium company and containing reliable measured data of roll load and torque is considered. Percentage reductions range from 6% to 20% and are analysed by a commercial thermo-mechanical coupled FEM program FORGE3 V5.3. An inverse analysis method is adopted to match the calculated rolling force and torque with the measured rolling force and torque by treating the friction law and the friction coefficient as free parameters. Three widely accepted friction laws are investigated; Tresca friction, Coulomb friction and viscoplastic friction. The use of viscoplastic friction is shown to yield both more reliable and more accurate results than other models. Significantly the friction coefficient can be traced to remain constant throughout the pass schedule of the breakdown rolling. The contact pressure distribution is then studied with different thickness reductions and compared with published experimental results. The predicted and experimental agreement is such that the load calculation can be regarded as satisfactory. Acceptable agreement is also obtained with the measured torque values. The distribution of equivalent strain, temperature and the stress in the roll gap and the lateral profile are discussed.