An experimental investigation on the deformation behavior during wire flat rolling process

In the present study a laboratory flat rolling machine is utilized to assess the deformation behavior of low and high carbon steel wires in wire flat rolling process. The effects of friction coefficient, rolling reduction and roll speed on rolling force and deformation behavior of the wires are experimentally investigated. It is found that the roll speed affects considerably the rolling force but a negligible effect on deformation behavior. It is noted that by increasing the roll speed, the rolling force may decrease or increase depending on the magnitude of the roll speed. Also, the deformation behavior of the wires in flat rolling is formulated. A relationship is developed for calculating the width of contact area between the wire and rolls as a function of rolling reduction. This relationship depicts that the width of contact area is proportional to square root of rolling reduction. Furthermore, two relationships are derived to predict the spreading of the wires after flat rolling. It is found that the relationships are applicable for both the low and high carbon steel wires.     

Investigation on Temperature Change of Cold Magnesium Alloy Strips Rolling Process with Heated Roll

Magnesium alloy strips are widely used in aerospace, automotive industry, etc., which are difficult to produce through cold forming process due to their poor deformation ability. In this article, we studied whether the rolling process with heated roll could be used to roll cold magnesium alloy strips. Thermal-mechanical finite element simulation of the rolling process, using heated roll and cold strips to produce the magnesium alloy strips, was carried out. Influences of roll temperature, rolling velocity, rolling reduction ratio, and initial strip thickness on the thermal field and the mean temperature of magnesium alloy strips were analyzed. Both the heated area in strips in rolling deformation zone and the mean temperature of strips at exit of rolling deformation zone increase with increasing the roll temperature and/or rolling reduction ratio, and/or with decreasing the rolling velocity and/or initial strip thickness. Finally, a formula was developed to predict the mean temperature of strips under different rolling conditions, which also could be used to calculate the critical value of parameters in rolling process.     

用板坯切分法轧制H型钢异型坯的实验研究

以１∶７的模拟比,用板坯切分法对轧制Ｈ型钢异型坯的变形行为进行了实验研究,并简要分析了异型坯的腿部宽展与来料厚度、宽度、轧辊直径、楔高、楔角以及压下量的关系     

关于大减壁量斜轧延伸工艺的研讨

论述了二辊斜轧管机的连轧特征及其特殊的变形规律,剖析了 Accu Roll轧机变形能力较小的原因和提高其变形能力的途径。论证了短顶头二辊斜轧管机是单机变形能力最大的轧管机,讨论了其各道次减壁量的确定原则和分配规律,举例介绍了其连轧孔型与变形工具的科学设计原则、步骤、内容及其内外减壁区的计算方法。     

冷轧带钢平整机高精度高速度轧制力模型开发

与普通冷轧相比,平整轧制压下量很小,轧件的弹性变形和工作辊的弹性压扁对轧制压力分布有较大影响,通常的圆弧形轧辊轮廓假设不再合理。文章推导了分段二次曲线分布压力作用下轧辊弹性压扁量的计算模型,考虑轧制速度对变形抗力的影响,采用卡尔曼理论计算轧件的弹塑性变形,研究开发了冷轧带钢平整机轧制压力模型。轧制力计算值与实测值吻合精度高,计算速度快,表明,本模型可以用作平整轧机的轧制力设定模型。     

A dynamic model of the rolling process. Part II: inhomogeneous model

Mathematical models representing the static rolling process have attracted considerable attention in the past, resulting in analytical, numerical, or graphical solutions obtained under various degrees of simplification and constraints. Most models, however, can only be used under steady conditions, and therefore are not suitable for the study of rolling chatter. An enhanced analytical process model that can handle dynamic variations exerted by roll vibrations in multiple directions is proposed in this paper, and its linearized form established for easy analysis. Finally, experiments are presented that verify the accuracy of the proposed dynamic model of the rolling process.     

基于影响函数法的冷轧带钢轧制力计算

根据经典轧制力模型 ,在考虑轧制力模型与轧辊压扁模型耦合的前提下 ,开发了基于影响函数法的冷轧带钢轧制力计算程序 ,并用实际生产中的采样数据模拟计算了HC轧机各道次的轧制压力分布和总轧制力 ,将所得计算结果与现场实测数据进行比较。结果表明 :所得轧制力计算结果与实测值相近 ,轧制压力分布与实际相符 ,为HC轧机板形控制提供了一种计算轧制力的有效方法。     

铝带坯铸轧过程轧制压力的建模与仿真研究

利用切块法分别推导出铸轧过程上述两区的静力平衡微分议程,在所建立的轧制压力模型的基础上,对常规铸轧进行了仿真计算,计算结果与实测数据相吻合,在此基础上,对快速铸轧进行了虚拟仿真研究,研究结果表明,减薄铸轧板坯厚度可提高铸轧速度;随着铸轧速度降低,铸轧区增大与铸轧坯厚度减薄,轧制压力峰值增大,随着铸轧辊径增大,轧制压力增大,因此铸轧机力能的设计参数也要相应增大。     

Influence of roll radius on contact condition and material deformation in skin-pass rolling of steel strip

Skin-pass rolling (or temper rolling) is the final forming step in the production of cold rolled steel sheets. Although a large roll radius compared to the contact length is one of the characteristics of skin-pass rolling conditions, numerous studies have been conducted thus far using laboratory mills with small radius rolls. In this paper, the influence of roll radius on the contact condition and material deformation in skin-pass rolling is examined and clarified by numerical analysis by an elastic–plastic FEM analysis as well as experimental rolling tests, which were performed to verify the result of the analysis. Some characteristics of skin-pass rolling related to pressure distribution, contact condition and material deformation are not properly simulated using small radius rolls. Considering characteristic skin-pass rolling conditions, two cases using simplified models, i.e., vertical compression and rolling with a circular, rigid roll, were analyzed.     

冷连轧过程工作辊辊间接触模型研究

辊间接触对高速冷连轧过程有重要影响。针对1 750 mm冷连轧机组的设备与带钢轧制的工艺特点,通过对UCM轧机辊系的受力分析,采用离散化处理方法和影响函数法,建立了辊系弹性变形影响函数模型、轧辊压扁影响函数模型,并给出了辊系变形的基本物理方程,基于接触力学,最终提出了冷连轧过程中工作辊辊间接触判定准则,为精确计算工作辊间的压力分布提供了理论依据。同时,研究了工作辊辊间接触对单位宽度轧制力分布、工作辊与中间辊辊间单位压力分布、工作辊弯曲挠度和压扁量分布以及成品带钢横向厚度分布的影响。实践证明,建立的辊间接触和辊系变形计算模型具有较高的计算精度,能充分反映轧后带钢的横向厚度分布和板形分布规律,适合于工业生产实践。     

板带热轧工作辊热凸度模拟软件的研究

根据热轧带钢工作辊在工作中的实际传热情况, 将工作辊对称地分为轧制区、非轧制区、辊肩、辊端和辊颈5个部分, 充分考虑热轧工作辊的实际环境对轧辊温度场和热变形的影响, 来确定轧辊的热边界条件; 再利用有限差分法建立工作辊温度场及热变形的数学模型, 并利用VC++平台进行模拟研究, 建立适合在线计算的快速模拟软件; 最后分析了轧辊直径和压下率对轧辊热凸度的影响。     

Large area rolling of functional metallic micro structures

The reliable fabrication of functional surface structures has become an important factor in modern production processes. With regard to the field of large area micro patterning, particular applications demand for economical manufacturing processes to gain advantageous surfaces. The process-integrated rolling of these structures is a promising approach if suitable roll geometries can be manufactured. This paper focuses on the large area rolling of so called riblet structures. Both experimental test series and related numerical forming simulations are taken into account. Furthermore, demands and potentials from the roll manufacturing point of view are highlighted. Above all, the feasibility of a new winding concept for the continuous patterning of rolls with small negative riblet structures is pointed out. By this means, challenging requirements in connection with riblet rolls—the realization of finest structures with sharp ground radii—can be matched.     

Roll force,torque, lever arm coefficient,and strain distribution in edge rolling

Due to the growing importance of width control in strip and plate mills, edge rolling is currently an im-portant process in hot rolling mills. Research in edge rolling has been carried out, and in the present ar-ticle, models for roll force, torque, and lever arm coefficient are derived using the upper bound method. A simple, kinematically admissible deformation zone and velocity field, independent of friction in the roll gap, is proposed, and the energy dissipation rate is derived. The formula for energy dissipation rate has, in practice, no limitation because all edge rolling geometries are safely in the area where the formula is valid. Roll force and torque are derived by means of two independent integrals. Thus, the lever arm coef-ficient is evaluated from the expressions for roll force and torque using conventional rolling theory. Roll-ing trials report good agreement with theory. Measured roll forces are similar to calculated forces. Furthermore, the shape of the dogbone that arises during edge rolling is in fairly good agreement with the calculated dogbone shape. Deviations are due to the deviation from ideally plastic material in the ex-periments. Also, the strain distribution over the dogbone is similar to the proposed deformation zone. Thus, a new formula has been developed to a stage that it can be implemented in width control systems for edge rolling stands in hot strip and plate mills.     

Effect of rolling parameters on cold rolling of thin strip during work roll edge contact

In some cold rolling mills, a problem has been found that the sides of work rolls touch and deform when thin strip is rolled. The problem of work roll contact at the edges, which forms a new deformation feature in rolling, is analysed. In this paper, the authors focus on the research of the effects of rolling parameters on specific force such as rolling force, intermediate force, edge contact force and the profile of thin strip in cold rolling when the work roll edges contact. An influence function method is developed to simulate this special rolling process. Based on numerical simulation, the effects of the rolling parameters on the mechanics and deformation of the cold rolled thin strip are obtained. Numerical simulation tests have verified the validity of this developed method.     

全浮动芯棒连轧管机组的轧机刚度实测分析

采用自行设计制造的轧制力传感器和辊缝仪,对宝山钢铁股份有限公司Φ140mm全浮动芯棒连轧管机组的轧制力与辊缝变化值进行了在线测试,得到不同材质不同规格连轧荒管的辊缝变化值△S随轧制力P的变化结果;根据所测数据的线性回归,得到全浮动芯棒连轧管机组的轧机刚度系数为5530kN/mm。     

Surface flexible rolling for three-dimensional sheet metal parts

To realize highly effective and continuous fabrication of three-dimensional (3D) sheet metal parts, a new forming method, surface flexible rolling forming, has been investigated. This method takes only two integral flexible rolls as the forming tool. In the forming process, a non-uniform elongation in the rolling direction and a bending deformation in the thickness direction occur simultaneously, and finally three-dimensional surface parts are formed. In this work, the basic principle and forming mechanism of surface flexible rolling are studied. A method to calculate the transversal curvature radius of the arc-shaped roll is brought forward, while the feasibility is verified by the explicit dynamic finite element analysis. An experimental device has been developed and the forming experiments have been performed. Typical 3D surface parts including the convex and saddle surface parts have been obtained. Finite element model of surface flexible rolling is established and the effect of forming parameters such as reduction, velocity, bending radius and friction on the surface shape is analyzed. The forming effects including shape errors and thickness changes are studied by the deviation analysis. The results indicate that the formed surface is quite close to the criteria one; the thickness of the parts changes gradually and keeps within a narrow range. The experimental formed parts are measured and the forming accuracy is investigated. The results show that the accuracy is high, and are consistent with the simulation.     

高速线材轧机孔型系统分析

介绍高速线材孔型系统的特点,并对其变形参数及其变化规律进行分析,为高速线材轧机的孔型设计提供依据。     

An Analytical Modified Model of Clad Sheet Bonding by Cold Rolling Using Upper Bond Theorem

In this paper, clad sheet bonding by cold rolling was investigated using the upper bond theorem. Plastic deformation behavior of the strip at the roll gap was investigated, unlike previous methods; distinctive angular velocities are used for different zones in roll gap in present model and absolute minimum of rolling power function is achieved. Rolling power, rolling force, and thickness ratio of the rolled product affected by various rolling condition such as flow stress of sheets, initial thickness ratio, roller radius, total thickness reduction, coefficient of friction between rollers and metals and between components layer, roll speed, etc., are discussed. It was found that the theoretical prediction of the thickness ratio of the rolled product, rolling force, and rolling power are in good agreement with the experimental measurement.     

全浮动芯棒连轧管机组轧件与芯棒速度及摩擦系数研究(上)

对宝山钢铁股份有限公司的全浮动芯棒连轧管机组各机架轧制压力、芯棒运动速度等一系列参数进行了综合测试,获得了轧件速度曲线,并探讨了轧件与芯棒速度之间的关系;分析了轧件与芯棒间的摩擦状态,并推算出两者间在各机架处的摩擦系数(为0.033～0.074),该系数沿轧制方向呈增大的趋势。以上结果为清楚认识连轧管过程中金属变形规律和芯棒摩擦作用机理提供了依据。     

Improved Process Design and Quality for Gear Manufacturing with Flat and Round Rolling

This paper describes a new method and its results in the roll-forming of gears that has significantly surpassed the conventional limits known till now. The method describes the rolling process and an alternative pitch design of forming tools. A model was created to analyze rolling processes which determined that in contrast to flat rolling tools, round tools need additional kinematic compensation during diameter-related variable pitch forming processes. This presented method shows up to a 50% improvement in pitch accuracy and the ability to roll high teeth gears (up to 10 mm in height and a tooth-height-coefficient larger than 2).