硬质合金轧辊在张力减径机上的应用

介绍了钢管张力减径机上所使用的硬质合金轧辊的材料、结构、孔型的加工和安装及冷却.生产实践证明,在热轧无缝钢管张力减径机上使用硬质合金轧辊使用寿命为铸铁轧辊的20～50倍,具有明显的技术优势和经济效益.     

钢管张力减径过程中直径与壁厚的确定

无缝钢管在张力减径过程后通常会出现表面质量差、尺寸精度低和横向壁厚不均匀等问题,有必要对张力减径过程中各机架减径率进行合理分配以及精确计算各机架出口侧的外径和壁厚。采用幂函数分配通式进行工作机组减径率的设计和引入径壁比确定张力系数的办法可以准确预测钢管经过张力减径机组各机架后的直径和壁厚。通过试验验证,该方法可以满足实际生产要求。     

无缝钢管张力减径过程的有限元模型开发及应用

为了研究热轧无缝钢管张力减径过程的金属变形,利用组元建模原理,把张力作为相邻机架之间的边界条件,使得张力减径过程分为机架上的轧制变形过程和机架之间的网格再生过程。建立高阶拟合函数来精确描述轧辊孔型曲面,应用摩擦元模型来模拟接触摩擦,并用正割模量法来求解非线性方程组,在上述理论基础上开发张力减径弹塑性有限元模型,利用该模型对某厂张力减径机组进行有限元建模分析。通过与实际轧制结果比较可知,模拟计算与实际轧制的产品断面形状接近,都呈现轻微内六方形状,且壁厚变化规律一致,几何尺寸与实测值吻合良好,表明所开发的钢管张力减径弹塑性有限元模型能够满足工程计算要求,为预测断面形状和终轧尺寸精度提供有效研究手段。     

张力减径机轧辊车床车刀的改进

张力减径机孔型的加工精度直接影响成品钢管的外表面质量,经过对轧辊车刀的改进,解决了长期困扰生产的钢管表面青线缺陷的问题,取得了较好的实际效果和效好的经济效益。     

张力减径机孔型设计初探

对张力减径机轧辊孔型设计做了大量的实验和研究，提出了孔型设计的基本方法。经实践验证，方法合理，生产的产品符合国家标准和用户要求。     

无缝钢管热轧生产过程中的轧辊孔型匹配问题

针对无缝钢管热轧生产过程中给定轧制计划下的轧辊孔型匹配问题,以最小化轧辊车削量为优化目标,建立了能够综合表述不考虑轧辊重用的静态轧辊孔型匹配和考虑轧辊重用的动态轧辊孔型匹配两种情形的0-1整数规划模型。对静态轧辊孔型匹配问题提出最少车削量匹配准则,并证明了该准则的最优性;对动态轧辊孔型匹配问题,证明了在最少车削量匹配准则下,动态轧辊孔型匹配的结果不劣于静态轧辊孔型匹配。基于问题性质的分析,针对问题模型设计了基于动态候选轧辊集合和最少车削量准则的启发式算法。通过基于实际生产数据的算例和仿真实验,验证了模型和算法的有效性。     

高精度方、矩形管孔型的优化设计

针对高精度方、矩形管孔型进行优化设计计算 ,包括管坯尺寸的确定 ,各机架延伸系数的分配 ,各机架减径及孔型高度、弯曲角度、弯曲半径的精确计算。如水平辊、立辊孔型均采用对角开口方式 ,成型质量便会提高 ,并使钢管表面划伤降低到最小程度。     

[成形过程仿真优化与集成计算材料工程]限动芯棒连轧管机轧制过程轧件变形行为及规律仿真

基于ABAQUS有限元软件建立了180 mm限动芯棒连轧管机组钢管连轧过程仿真模型。通过仿真模拟展现了连轧各机架连续轧制过程中轧制区钢管横截面上应力、应变及位移的分布和壁厚形成演变过程，揭示了轧制压力分布和轧辊上总轧制力的变化规律以及轧件温度与轧制区摩擦因数对壁厚与轧制力的影响。使用三次样条插值方法从仿真结果数据中提取钢管壁厚和直径，通过研究对象机组的工业生产实测数据验证了有限元模型的正确性。仿真发现:连轧过程中，金属在纵向上先发生减径变形后发生减壁变形，横向上金属主要从孔顶区流向开口区；前三机架接触压力主要集中在孔顶区，变形量较大，是主变形机架，第四五机架接触压力最大在侧壁区，变形量较小，主要起到精整和归圆作用；随着轧制温度的升高，出口壁厚增大，轧制力减小，随着芯棒与轧件之间摩擦因数的增大，壁厚减小，轧制力减小。仿真研究结果支撑了针对该机组的关键轧机结构参数设计、轧制工艺参数确定以及工程调试中工艺参数优化。     

高精度方,矩形管孔型的优化设计

针对高精度方,矩形管孔型进行优化设计计算,包括管坯尺寸的确定,各机架延伸系数的分配,各机架减径及孔型高度,弯曲角度,弯曲半径的精确计算。如水平辊,立辊孔型均采用对角开口方式,成型质量便会提高,并使钢管表面划伤降低到最小程度。     

CRTM-350冷轧管机孔型设计基本原理

根据某钢厂专用冷轧大直径不锈钢钢管的三辊冷轧机的轧辊特点,探索其轧辊孔型设计的基本原理,以便更好地为其孔型设计服务。     

巧用宏程序加工椭圆

在数控编程的实际应用中,常见的是直线插补和圆弧插补,没有椭圆插补,但在实际生产中,往往遇到许多椭圆的零件需要加工,如果手工常规编程就无法编制出椭圆的加工程序,为了解决这个问题,在数控编程中有宏程序可以做到椭圆的加工,本文按HCNC-21T系统（在其他系统只不过是宏程序的格式不同而已）对椭圆做内、外的加工编程举例,还在内椭圆的加工中先加工一个工艺孔,巧妙利用椭圆的参数方程来编写宏程序,用宏程序来解决一些实际的工作问题。     

走廊清扫机的三维设计

走廊清扫机的能源装置通过传动系统将运动传给两侧的盘形刷,使其分别作顺时针和逆时针转动.将两侧的垃圾扫到中间,传给中间的滚刷.然后,再由滚刷将垃圾扫入垃圾箱内实现清扫的功能.它可以对各种大小的垃圾进行清理,两侧的清扫刷可方便地清扫墙角及靠近障碍物的地方.     

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.     

Investigation of the effect of roll forming pass design on main redundant deformations on profiles from AHSS

The tooling design in the roll forming process plays a major role in the quality and successful mass production of a variety of complex profiled products, in many industrial sectors. The roll forming line is comprised of consecutive forming passes. Each roll forming pass consists of a set of rotating rollers able to bend the material as it passes through them. The roll forming pass design plays a major role in the production of profiles. The introduction of advanced high strength steels (AHSS), such as the DP-series and TRIP-series, has also posed new challenges for the design of the roll passes. The current paper exploits explicitly the finite elements (FE) method and investigates the effect of the roll forming passes design on main redundant deformations, such as longitudinal stains at the edge of the profile, shear strains on strips plane, thickness reduction, and final produced cross section with springback. The profiles discussed are symmetrical V- and U-sections from the AHSS Dual Phase series (DP780). The gradual lowering of the flower pattern design, known as ??downhill pass flow??, is discussed. The calculated decrease in the peak longitudinal strains of up to 28%, and the decrease in thickness of up to 38% are also presented and discussed.     

An upper bound analysis for the reshaping of thick tubes with experimental verification

Reshaping process based on the cold roll forming technology is a process in which noncircular pipes can be produced from circular pipes. A generalized upper bound solution for the deformation of thick tubes between four flat rolls has been formulated. The deforming zone has been divided into two areas namely the “contact region” and the “free region”. Owing to the different physical character of these deforming zones two different kinds of admissible velocity fields have been obtained for each of the deforming zones. To formulate the stream lines and stream surfaces in the deforming zones use has been made of the Bezier curves which have been utilized to define stream lines in such a way that could be manipulated easily to obtain the optimum shape for the upper bound solution to be optimized. This new formulation was used to predict the upper bound on power. Using the theory presented here, the influence of process parameters such as radius of rolls, initial pipe dimensions; amount of roll gap reduction and the roll speed on the final rolled product were investigated. In order to verify the theoretical results, an experimental rolling rig was designed and built which comprised of four flat rolls. Using this rig Al 6101 round pipes were rolled and the variations in the above-mentioned parameters were investigated. Quantities such as energy, wall thickness, and corner radius of the tube were observed and measured. Comparison of theoretical and experimental results showed good agreement and hence demonstrated the capabilities of the new formulation presented here.     

A novel continuous roll forming process of sheet metal based on bended rolls

To effectively manufacture three-dimensional sheet metal parts with various curvatures produced in small-batch quantity, a continuous roll forming (CRF) process is proposed and investigated. The sheet metal is compressed between pairs of bended rolls and formed into a doubly curved surface. The shapes of forming rolls and the gap between the two rolls are piecewise controlled at a series of points. The two bended rolls and the nonuniformly distributed roll gap between them make the sheet metal bent in longitudinal and transverse directions simultaneously after the sheet metal passes through the roll gap, and a three-dimensional surface is formed continuously with the rotation of forming rolls. The relation between longitudinal elongation distribution and longitudinal bending deformation is discussed, and the lateral spreading in CRF process is analyzed; the method to compute the roll gap and the curved profiles of forming rolls are presented. Forming experiments for torus-shaped surface parts were carried out, and the experiment results demonstrate the feasibility and validity of CRF process and the presented methods.     

内压及扭矩载荷下无缺陷弯管的应力分析

分析在内压或扭矩载荷作用下非均匀壁厚椭圆弯管的应力分布，结果表明内压引起的最大应力随着弯管的截面不均匀度而变化，由此解释了工程实际中弯管失效的原因，同时也为求解弯管的塑性极限载荷奠定了基础。     

Texture control and grain refinement of AA1050 Al alloy sheets by asymmetric rolling

Asymmetric rolling, in which the circumferential velocities of the upper and lower rolls are different, can give rise to intense plastic shear strains and in turn shear deformation textures through the sheet thickness. The ideal shear deformation texture of fcc metals can be approximated by the {0 0 1}1 1 0 plus 1 1 1ND orientations, among which the latter improves the Lankford values or the deep drawability. The intense shear strains can result in the grain refinement and hence improve mechanical properties. In this paper, a study has been made of effects of asymmetric rolling variables such as reductions per pass, changes in shear direction each pass, reductions in the last pass, roll rotation rate ratios, changes in shear direction in the last pass, and different frictions on the upper and lower surfaces of AA1050 Al alloy sheets on the evolution of their deformation and annealing textures and grain refinement.     

Optimization of shape rolling sequences by integrated artificial intelligent techniques

The present work introduces an expert system that automatically selects and designs rolling sequences for the production of square and round wires. The design strategy is aimed at reducing the overall number of passes assuming a series of process constraints, e.g., available roll cage power and torque, rolls groove filling behaviors, etc. The method is carried out into two steps: first a genetic algorithm is used to select the proper rolling sequence allowing to achieve a desired finished product; then, an optimization roll pass design tool is utilized for proper design of roll passes. Indeed, an artificial neural network (ANN) is utilized to predict the main geometrical characteristics of the rolled semi-finished product and technological requirements. The ANN was trained with a non-linear finite element (FE) model. The proposed methodology was applied to some industrial cases to show the validity of the proposed approach in terms of reduction of number of passes and search robustness.