A theoretical and experimental investigation into asymmetrical hot rolling

A simple slip-line field solution for asymmetrical hot rolling is investigated and used to predict the sign and magnitude of the curvature of the rolled strip. These predictions are compared with measurements from a two high model rolling mill.     

扁钢精轧过程的数值模拟与分析研究

为了建设资源节约型社会,金属轧制技术作为一种少切削或无切削加工的高效、节约的生产手段是值得提倡的。针对轧件精度的提高等问题,以轧制理论为基础,基于有限元软件Deform-3D建立了扁钢轧制件的有限元模型,采用适当的加载和约束条件,对单、双道次轧制成功地进行了仿真模拟,详细分析了厚度、轧辊转速、轧辊直径、温度等因素对轧件精度和功率的影响。并且针对单、双道次轧制仿真进行了模拟,分析了轧件等效应变和等效应力情况。研究结果表明:经过双道次轧制的轧件精度偏差在0.005 4~0.107 2之间,对于提高轧件精度起着至关重要的作用,有效地验证了有限元模型的合理性,分析结果对现场生产有着重要的指导意义。     

Hydrodynamic analysis of partial film lubrication in the cold rolling process

Lubrication in cold rolling plays an important part for process feasibility and process quality. The hydrodynamic process of lubrication is very complicated and affected by many material and process parameters. This paper examined partial lubrication in the cold rolling process. The average flow Reynolds equation for rolling lubrication was 2set, which considered the pressure?Cviscosity and average flow effects. Lubricating factors such as sidling, surface waviness, lubricant viscosity, surface roughness, and reduction ratio were investigated. The results of the lubrication equation show that sliding, lubricant viscosity, and surfaces roughness affect the values of rolling friction. Surface waviness and reduction ratio also influence both rolling pressure and rolling friction.     

Analysis of sandwich sheet rolling by stream function method

A mathematical model for symmetrical sandwich sheet rolling is proposed by using the stream function method and the upper bound theorem to investigate the plastic deformation behavior of sheets at the roll-gap. The velocity fields derived from the newly proposed stream functions can automatically satisfy the volume constancy and the velocity boundary conditions within the roll-gap. Effects of various rolling conditions such as the thickness ratio and flow stress ratio of sheets, total thickness reduction, friction factor between the sheet and roll, etc., upon the thickness ratio of the rolled product, the relative length of the plastic region in each layer, rolling force and rolling power are discussed systematically. Furthermore, experiments on sandwich sheet rolling are also conducted by employing aluminium, mild steel and stainless steel as layers of sandwich sheets. It is found that the theoretical predictions of the thickness ratio of the rolled products and rolling force are in good agreement with the experimental measurements. Through the study, it becomes clear that the proposed analytical method is applicable for simulating the sandwich sheet rolling processes and is able to offer useful knowledge in manufacturing sandwich sheets.     

摆碾铆接过程数值模拟分析

应用DEFORM-3D有限元分析软件建立碾压铆接有限元模型,对摆碾铆接工艺过程进行数值模拟。分析了其成形过程的三个阶段、应力应变和行程载荷曲线的变化趋势,结果表明最大应力应变都集中在铆钉头部边缘区,边缘区点最先受到旋压力开始变形,最早发生屈服现象并进入弹塑性变形阶段;铆钉在相同行程下达到相同的成形效果时,碾压铆接需要的载荷要远远低于传统铆接的载荷。最后分析了影响碾压铆接质量的几个核心因素,如铆头速度、铆头倾斜角度等,为有效地进行碾压铆接工艺研究提了供理论依据。     

A theoretical study on the application of asymmetric rolling for the estimation of friction

In this work, a method for the estimation of friction coefficient is proposed based on the asymmetric rolling operation. Asymmetry is produced by operating the lower and upper rolls at different speeds. A slab method based computer code is developed for estimating the curvature of the rolled sheet under asymmetric rolling conditions. Strain-hardening behavior of the material has been incorporated and Wanheim and Bay's friction model is employed. The developed code is used for solving the inverse problem of estimating the coefficient of friction by measuring the curvature of the rolled sheet under known operating conditions. The simulations show a good potential of the method.     

宽厚板轧制过程有限元模拟分析

以大型ANSYS软件中的LS-DYNA模块为平台,对鞍钢5500mm轧机轧辊和板带进行建模。通过设置板带的咬入速度、轧辊的角速度、压下量等初始条件,动态模拟四组不同板宽的单道次轧制过程和施加三组不同压下量的单道次轧制过程,进而分析宽厚板轧制过程中的应力、应变以及板带轧后凸度的变化情况。最后,把模拟结果与现场板带轧制实际数据进行比较,验证分析结果的准确性。分析结果对提高宽厚板产品的质量和精度都具有重要的理论意义和应用价值。     

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.     

加工滚丝轮重点工序浅析

针对滚牙滚丝轮重点工序加工时出现的问题,提出解决问题的具体方法,提高了生产效率和产品质量。     

CVC轧辊横移轧制钨板过程的有限元分析

针对传统轧制工艺轧制钨板过程中,轧辊易损坏、钨板轧废严重等现象,查阅国内外相关文献,基于有限元分析软件DEFORM,研究利用CVC轧辊横移轧制钨板,根据要求选择了一款CVC轧辊,并建立了有限元分析模型,从辊形、应力以及破坏方面,分析钨板轧制过程情况,发现同等轧制条件下,CVC轧辊横移轧制钨板轧制应力是传统工艺的3/4左右,对轧机的负荷较轻.结果表明:CVC轧辊横移轧制钨板的新工艺优于传统直线辊形轧辊轧制钨板的工艺.     

无缝钢管张力减径过程壁厚不均匀模拟分析

为研究无缝钢管张力减径过程中钢管壁厚不均现象,建立无缝钢管张力减径过程三维热力耦合模型。模拟所得壁厚与实测结果误差最大不超过5.2%。模拟结果直观显示钢管在轧制过程中内壁形状的变化过程,最终内壁形状为规则的正六方形。分析张力减径过程中摩擦力的分布,结果表明,摩擦力沿钢管圆周分布不均,使得在辊底处形成附加轴向压应力,辊缝处形成附加轴向拉应力,从而影响壁厚变化不均。进一步研究钢管初始温度对成品壁厚分布的影响,模拟结果表明,随着钢管初始温度的升高,钢管壁厚不均现象得到明显改善。     

板带热轧三维有限元热力耦合仿真分析

采用更新的Langrange方法及大变形热力耦合有限元法对热轧过程进行了热力耦合仿真分析,经过多道次轧制仿真后,得出了轧件的温度场和轧制力分布以及每道次轧件入口与出口温度大小及轧制力的大小,并进行了现场工业实验对仿真结果进行了验证,计算结果表明,仿真所得结果与实测结果误差很小,均在5%之内,从而证明模型是正确的,能够很好的运用于热轧过程的参数计算和研究,并对以后热轧工艺参数匹配规律研究以及板形控制研究提供重要的分析平台和起到重要的指导作用.     

The rolling process effectivity evaluation method based on the spectral analysis of the surface geometrical structure

A new technique for rolling process (RP) effectivity evaluation which employs a spectral analysis method to examine the surface geometrical structure (SGS) is introduced. This makes it possible to detect the presence of surface components after turning in rolled surfaces and to detect a newly formed SGS during the RP.From experiments that were carried out it can be concluded that the presented technique is useful for effectivity evaluation during the smoothing of surfaces and helpful in the investigation of the RP for the prediction of the functional behaviour of the surface.     

A slipline field analysis of asymmetrical hot rolling

A slipline field solution covering a range of geometries of asymmetric hot rolling of strip is presented. A number of computations of strip curvature, roll forces and torques are presented and are compared with experimental data.     

端面齿轮滚压加工技术研究

针对端面齿轮的加工,提出了不同于传统加工的端面齿轮滚压加工新工艺。根据滚压加工技术要求,对使用设备和工装进行了设计,根据实验测出的数据,从轮齿齿顶卷曲、轮齿精度、表面硬度和滚压的加工效率进行了分析并得出结论:小模数端面齿轮滚压加工切实可行,为进一步实现端面齿轮滚压加工工业化推广奠定了基础。     

Grain boundary sliding of copper in the rolling process

In the case of severe wear of copper rubbing against SAE 1045 steel it has been assumed that grain boundary sliding as well as sliding in the grains may be an essential deformation mechanism. This assumption has been verified in heavily cold rolled copper by means of grain thickness measurements using the linear intercept method.