平整机轧辊直径配合对翘曲问题影响研究

随着用户对带钢质量要求的日益提高,生产部门对带钢质量的控制显得尤其重要。近期,某冷轧厂收到用户反馈,连退带钢在用户处开卷后出现L翘问题。对此,技术人员展开调研,以某冷轧厂连退生产线平整机工作辊与带钢为研究对象,探索辊径配合对L翘的影响关系。首先对L翘产生的原因进行了分析,而后建立了工作辊与带钢的有限元模型,对两种辊径配合轧制带钢进行仿真模拟,提取的结果表明,将小辊径的轧辊用于上辊、大辊径轧辊用于下辊时,可防止带钢出现向上翘曲问题。     

基于BP网络逆模型的轧辊偏心自适应逆控制

针对冷轧带钢生产中的轧辊偏心控制问题,将神经网络与自适应逆控制相结合,提出一种基于BP网络逆模型的自适应逆控制方法。将系统的动态特性控制和对象的噪声控制分成两个独立的过程,当动态性能达到最优时,对象扰动的影响也减到最小。将该方法应用到350 mm四辊可逆液压轧机上,仿真结果表明,系统具有良好的动态和稳态特性。     

张力对轧制过程中接触应力影响的仿真研究

以冷连轧机组第一机架的工作辊与带钢为研究对象,探索相同压下量条件下,不同张力对轧辊与带钢间接触应力的影响关系问题,应用有限元软件ABAQUS对不同工况下轧制过程进行仿真,提取的结果定量描述了不同张力对轧制压力的影响关系。模拟结果表明,增加前张力或后张力均能够减小轧制时轧辊与带钢间的接触应力,且后张力影响较前张力更加明显。     

柳钢1550mm冷轧带钢厚度控制系统的设计与实现

介绍了带钢厚度控制系统的基本原理及系统组成,给出了柳钢1550mm冷轧带钢厚度控制系统的总体结构,阐述了该系统的调试过程及实际应用效果。     

UCM轧机门户机架非对称轧制工况下跑偏研究及实践

门户机架为冷连轧机的第一机架,其稳定轧制对后续机架的运行起着重要的作用。而门户机架轧制时带钢跑偏作为影响酸轧生产线的一个重要问题,严重影响了其运行、产品质量,一直倍受技术人员的关注。主要研究调整带钢进入轧机的对中性对轧机跑偏的影响,以UCM轧机门户机架的工作辊与带钢为研究对象,分别建立了轧辊与带钢对称轧制与非对称轧制的有限元模型,探索了其与带钢跑偏的关系。结果表明,采用在纠偏辊处提前调整带钢对中性的方法能够有效防止跑偏的发生。     

电镀技术在机械备件修复中的生产应用

介绍了电镀技术在冶金、化工机械备件修复中的生产应用，并重点对带钢连续电镀机组的导电辊、冷轧机组的轧辊、炼钢机组的结晶器铜板、丙烷脱氢制丙烯机组的脱氢大阀的电镀修复与制造进行了阐述。     

带钢连续热镀锌层厚度控制技术的研究

镀锌层厚度控制一直是带钢连续热镀锌生产的重点和难点.针对DAK气刀的特点,分析了热镀锌生产工艺和设备对镀锌层厚度的影响,总结了镀锌层厚度控制的主要方法,提出了提高镀锌层厚度控制精度的措施.     

信息资讯

中冶连铸宽幅带钢连续电镀镍技术填补国内空白2009年11月4日,中冶集团所属中冶连铸技术工程股份有限公司成功进行了厚度0.25～1.20mm、宽度1000～1500mm等规格的宽幅带钢连续电镀镍试验生产,并实     

带钢保护气氛循环喷射冷却热工过程的数值模拟

对带钢保护气氛循环喷射冷却热工过程建立了一维非稳态传热模型,采用有限差分计算方法计算了带钢的温度场,确定了带钢在不同厚度、初始温度及运行速度下所需的综合换热系数,考察了喷箱的结构参数和循环冷却介质的物性参数对带钢出口温度的影响。结果表明,不同厚度的带钢在满足性能要求及安全的条件下,存在最大运行速度,厚度超过3 mm的带钢的断面温差对带钢性能的影响不能忽略;带钢出口温度会随带钢至喷孔板距离(?)与喷孔直径(D)的比值增大而增大,但增大速率随?/D增加逐渐变小。喷孔间距(?n)与喷孔直径的比值存在最佳范围,且与?有关,因此在实际设计喷箱结构时,不仅需考虑?n/D的最佳值,还需结合?综合考虑;冷却介质(H2+N2)的温度每升高10℃,带钢出口温度增加约3℃。带钢出口温度随冷却介质中氢气含量及流速增加而减小,但减小速率随二者增加而逐渐减小。现场应用结果表明,带钢出口温度的模拟值与实测值吻合较好,误差约为3.4%,满足应用要求。     

基于BP神经网络的热镀锌产品表面粗糙度预报

为了满足使用客户对带钢表面粗糙度界限范围的严格要求,首先通过单因子方差分析方法确定影响镀锌产品表面粗糙度的关键要素,接着利用检验统计量F值量化研究各个关键要因的显著程度,最后以BP神经网络建立了综合考虑产品规格、轧辊特性、轧制参数等影响因素的热镀锌带钢表面粗糙度预报模型。现场实际情况表明,该预报模型偏差率在3%以内,具有较高的使用价值和推广价值。     

Effect of thickness and viscoelastic properties of roll cover on deformable roll coating flows

Roll coating is distinguished by the use of one or more gaps between rotating cylinders to meter a continuous liquid layer and to apply it to a flexible substrate. Of the two rolls that make a forward-roll coating gap, one is often covered by a layer of deformable elastomer. Liquid carried into the gap develops high enough pressure to deform the resilient roll cover. The complete understanding of the coupling between the liquid flow and roll cover deformation is vital to the optimization of this widely used and simple coating method. Most of the earlier works on deformable roll coating analyzed the action with both the lubrication approximation and the full Navier-Stokes solution of the liquid flow, and one-dimensional elastic models of the roll cover deformation. The effect of the roll cover thickness was not explored and can explain some of the discrepancy observed from the available theoretical predictions and experimental measurements from different researchers. Moreover, rubber and rubber-like materials used as roll covers do not behave purely elastically. Their responses depend to a great extent on the stress history and the temperature of the roll cover. In this work, the flow between a rigid and a deformable rotating roll was examined by solving the complete Navier-Stokes system coupled with a plane-strain elastic and viscoelastic model of the roll cover deformation. The stress at each location of the roll cover was evaluated by an integral of the deformation along the material path of the point being analyzed. The equation system was solved by the Galerkin/finite element method. Results show how thickness of the roll cover and its viscoelastic properties affect the performance of deformable roll nips.     

Analytical prediction of roll coating with counter-rotating deformable rolls

Roll coating is a common technique for applying thin coating films on continuous substrates, e.g., papers and foils. Key advantages are the comparatively simple technology and the possibility of coating thin films using highly viscous fluids. Since roll coating is a self-metered process, the prediction of film thicknesses is of fundamental interest for industrial process control. In the present work, a new analytical approach for the prediction of the film thickness in roll coating with deformable rolls and negative gaps is developed. This method is based on the fluid dynamic theory of lubrication approximation. The film thickness is calculated depending on the geometry of the rolls (including the elasticity of the rubber), the fluid properties of the applied film and the roll velocities. This is gained by using boundary conditions for pressure and—in contrast to former literature—for force. The quality of the predicted results is validated with experimental data from literature. The comparison shows good agreement and thus the derived analytical model offers new possibilities for predicting film thickness and understanding of the associated influence parameters.     

Fabrication of high modulus films by solid state rolling

Solid state rolling of semicrystalline polymers represents a high speed process for producing oriented, high modulus films, tapes, and sheets. The important process variables include roll temperature, thickness of initial sheet, roll speed, take-up tension, roll diameter, and initial morphological state of the polymer. Roll temperature controls both the extent of maximum deformation and the rate of rolling. A minimum temperature exists for each polymer below which the orientation process is sharply limited. This condition is similar to the limitation present in the hydrostatic extrusion process, in which the alpha crystallization temperature limits the orientation process. Roll speeds as high as 20 m/min have been realized. It is apparent that film thickness and thickness reduction ratio have a strong effect on the ultimate rolling rate. The process, as currently practiced, is adiabatic, and therefore, heat transfer limited. The take-up tension influences the extant of orientation in the amorphous phse of of the polymer. This in turn affects its thermal and chemical stability. The effect of roll diameter is to limit the extent of thickness reduction by causing roll-film slippage when the roll dianmeter to thickness reduction ratio is below some as yet undetermined value. The initial morphological state of the polymer affects the amount of crystalline deformation possible, the surface texture of the rolled film, and the tear resistant of the oriented film.     

Modelling the strip thickness in hot steel rolling mills using least‐squares support vector machines

The development and implementation of better control strategies to improve the overall performance of a plant is often hampered by the lack of available measurements of key quality variables. One way to resolve this problem is to develop a soft sensor that is capable of providing process information as often as necessary for control. One potential area for implementation is in a hot steel rolling mill, where the final strip thickness is the most important variable to consider. Difficulties with this approach include the fact that the data may not be available when needed or that different conditions (operating points) will produce different process conditions. In this paper, a soft sensor is developed for the hot steel rolling mill process using least‐squares support vector machines and a properly designed bias update term. It is shown that the system can handle multiple different operating conditions (different strip thickness setpoints, and input conditions).     

The coating of Newtonian liquids onto a roll rotating at low speeds

A theoretical treatment is presented for the prediction of the rate at which a liquid is entrained by a roll which is rotating partially submerged in a Newtonian liquid, and also for the prediction of the variation in the thickness of the film around the roll. The method involves the integration of the momentum equation after neglecting inertia forces in the dynamic meniscus region and the matching of the surface curvature with that derived for the static meniscus region near the liquid surface. The resulting equation allows the prediction of the relationship between a dimensionless film thickness parameter, T, and the capillary number, Ca, as a function of the radius of the roll, the withdrawal angle and the position of the roll periphery. The liquid flux on the roll can also be predicted.     

Design of a vane mixer with controlled extensional/shear strength ratio and its application for carbon fiber/polyamide 6 composites

In this work, a novel melt mixing method and its corresponding mixing device are developed. The extensional/shear strength ratio of the device can be controlled by adjusting its eccentricity. The structure and working principle of the device are introduced in detail. Carbon fiber (CF)/polyamide 6 (PA6) composites are prepared via this novel mixing device. The influences of eccentricity and mixing time on the morphology, CF length, thermal, mechanical, and electrical properties of CF/PA6 composites are studied. Scanning electron microscopy results show that CFs uniformly disperse in the matrix and interfacial adhesion between CFs and PA6 is improved. It is observed that CF length and its distributions can be optimized by changing eccentricity. The maximum average fiber length is about 351 μm. Differential scanning calorimetry results exhibit that the X_c increases 6.5% when eccentricity is 2 mm. Mechanical test results show tensile strength and modulus increase first and then decrease with the increasing eccentricities or mixing time. Electrical property measurement shows an obvious increase when eccentricity is 2 mm due to good fiber dispersion and long fiber retention length. The experimental results indicate that the novel mixing method and its corresponding apparatus provide an environment-friendly and effective way to prepare polymer-based composites.     

Stress Analysis of Generally Asymmetric Single Lap Adhesively Bonded Joints

An analysis is presented that predicts shear and peel stresses in an adhesively bonded single lap joint having general asymmetric configuration. The single lap joint is under tension loading together with moments induced by geometric eccentricity. Because these eccentricity moments are the key elements of this analysis, a general relationship between the eccentricity moments and simple geometric moments has been determined with the aid of finite element analysis (FEA). Example calculations show that the shear- and peel-stress profiles from the closed-form model are well matched to FEA results except in the small regions near the free ends of the joints, because of the shear lag basis of the model. For asymmetric joints, the model predictions are more accurate for the case of modulus eccentricity than thickness eccentricity. Elastic-limit load predictions accounting for both shear and peel stress in the adhesive have been used to find optimal joint configurations between asymmetric adherends.     

Cold rolling of polymers 2. Toughness enhancement in amorphous polycarbonates

The effect of cold rolling on the Izod impact strength of amorphous polycarbonates has been studied. The impact strength is a function of the roll reduction as well as the original sheet thickness. Sheets varying from 0.125 to 0.645 inches in thickness have been studied and roll reductions up to 50 percent have been utilized. It is shown that enhancement in impact strength occurs at very small percent roll reductions. The orientation release stress has been measured as a function of roll reduction and the internal stresses through the thickness of the sheets have been studied by birefringence methods. It is suggested that the residual stresses are responsible for impact enhancement rather than the molecular orientation.     

钢丝帘布压延线上辅机的设计与应用

介绍了钢丝帘布压延线上辅机锭子张力装置、电磁吸盘及整经压力辊的设计与应用情况。张力控制装置采用重锤式结构，重锤重量按公式Ｐ＝Ｆ１Ｄ２ｄｆ计算。电磁吸盘装置主要由机架、导辊、轴承、电磁吸盘和电控箱组成，左右两个靠近电磁吸盘的导辊调整的最佳高度是：在运行过程中大部分帘线与磁盘表面平行，只有个别张力值小于电磁吸力的帘线被磁盘吸附在其表面或处于若即若离的状态。整经压力辊装置主要由交叉板、整经辊、压力辊等组成。整经辊的沟槽深度等于帘线直径，压力辊的沟槽深度为帘线直径的一半。一般调整压力辊与３＃辊筒的间隙略小于所给的胶片厚度