Study of the Characteristics of Large-Diameter Iron Bars Obtained by Rolling at the ODHAV Foundry in the Republic of Guinea

This work consists of evaluating the quality of the mechanical parameters of large-diameter steels, i.e. 20, 25, 28 and 32, through a process of recycling scrap metal that fills garages, rubbish dumps, gutters and other abandoned sites, as well as imported concrete reinforcing steel sold in the Republic of Guinea. To carry out this important work, a number of mechanical tensile and bending tests and a microscopic analysis combining two devices, an electron microscope and a photographic camera, were carried out. The samples were taken from sampling areas in the major communes of Conakry, namely: Casse Sonfonia, Matoto and Kagbélen. The tensile strength values of the large dimensions 20, 25, 28 and 32 are given in the tables.

Research and Application of Non-symmetrical Roll Bending Control of Cold Rolling Mill

The existing research of the flatness control for strip cold rolling mainly focuses on the calculation of the optimum adjustment of individual flatness actuator in accordance with the flatness deviation, which can be used for general flatness control. However, it does not work for some special rolling processes, such as the elimination of ultra single side edge-waves and the prevention of strip break due to tilting roll control overshooting. For the purpose of solving these problems, the influences of non-symmetrical work roll bending and intermediate roll bending on flatness control were analyzed by studying efficiencies of them. Moreover, impacts of two kinds of non-symmetrical roll bending control on the pressure distribution between rolls were studied theoretically. A non-symmetrical work roll bending model was developed by theoretical analysis in accordance with practical conditions. The model was applied to the revamp of a 1250 6-H reversible universal crown mill (UCM) cold mill. Theoretical study and practical applications show that the coordination utilization of the non-symmetrical work roll bending control and tilting roll control was effective in flatness control when there appeared bad strip single side edge waves, especially when the incoming strip was with a wedge shape. In addition, the risk of strip break due to tilting control overshooting could be reduced. Furthermore, the non-symmetrical roll bending control can reduce the extent of uneven distribution of pressure between rolls caused by intermediate roll shifting in flatness control and slow down roll wear. The non-symmetrical roll bending control technology has important theoretical and practical significance to better flatness control.

Fuzzy Control System of Hydraulic Roll Bending Based on Genetic Neural Network

For nonlinear hydraulic roll bending control, a new fuzzy intelligent control method was proposed based on the genetic neural network. The method taking account of dynamic and static characteristics of control system has settled the problems of recognizing and controlling the unknown, uncertain and nonlinear system successfully, and has been applied to hydraulic roll bending control. The simulation results indicate that the system has good performance and strong robustness, and is better than traditional PID and neural-fuzzy control. The method is an effective tool to control roll bending force with increased dynamic response speed of control system and enhanced tracking accuracy.

Bending stress of rolling element in elastic composite cylindrical roller bearing

A new structure design method of elastic composite cylindrical roller bearing is proposed, in which PTFE is embedded into a hollow cylindrical rolling element, according to the principle of creative combinations and through innovation research on cylindrical roller bearing structure. In order to systematically investigate the inner wall bending stress of the rolling element in elastic composite cylindrical roller bearing, finite element analysis on different elastic composite cylindrical rolling elements was conducted. The results show that, the bending stress of the elastic composite cylindrical rolling increases along with the increase of hollowness with the same filling material. The bending stress of the elastic composite cylindrical rolling element decreases along with the increase of the elasticity modulus of the material under the same physical dimension. Under the same load, on hollow cylindrical rolling element, the maximum bending tensile stress values of the elastic composite cylindrical rolling element after material filling at 0° and 180° are 8.2% and 9.5%, respectively, lower than those of the deep cavity hollow cylindrical rolling element. In addition, the maximum bending-compressive stress value at 90° is decreased by 6.1%.

Bending analysis and control of rolled plate during snake hot rolling

In order to study the bending behavior of aluminum alloy 7050 thick plate during snake hot rolling, several coupled thermo-mechanical finite element(FE) models were established. Effects of different initial thicknesses, pass reductions, speed ratios and offset distances on the bending value of the plate were analyzed. ‘Quasi smooth plate' and optimum offset distance were defined and quasi smooth plate could be acquired by adjusting offset distance, and then bending control equation was fitted. The results show that bending value of the plate as well as the extent of the increase grows with the increase of pass reduction and decrease of initial thickness; the bending value firstly increases and then keeps steady with the ascending speed ratio; the bending value can be reduced by enlarging the offset distance. The optimum offset distance varies for different rolling parameters and it is augmented with the increase of pass reduction and speed ratio and the decrease of initial thickness. A proper offset distance for different rolling parameters can be calculated by the bending control equation and this equation can be a guidance to acquire a quasi smooth plate. The FEM results agree well with experimental results.

Preset model of bending force for 6-high reversing cold rolling mill based on genetic algorithm

The hydraulic roll-bending device was studied,which was widely used in modern cold rolling mills to regulate the strip flatness.The loaded roll gap crown mathematic model and the strip crown mathematic model of the reversing cold rolling process were established,and the deformation model of roll stack system of the 6-high 1 250 mm high crown (HC) reversing cold rolling mill was built by slit beam method.The simulation results show that,the quadratic component of strip crown decreases nearly linearly with the increase of the work roll bending force,when the shifting value of intermediate roll is determined by the rolling process.From the first pass to the fifth pass of reversing rolling process,the crown controllability of bending force is gradually weakened.Base on analyzing the relationship among the main factors associated with roll-bending force in reversing multi-pass rolling,such as strip width and rolling force,a preset mathematic model of bending force is developed by genetic algorithm.The simulation data demonstrate that the relative deviation of flatness criterions in each rolling pass is improved significantly and the mean relative deviation of all five passes is decreased from 25.1% to 1.7%.The model can keep good shape in multi-pass reversing cold rolling process with the high prediction accuracy and can be used to guide the production process.

Analysis of bending on the front end of sheet during hot rolling

The analysis of bending in finishing rolling was performed. An asymmetrical rolling force model was established, and the upper and lower neutral points were determined. Thc bending which resulted from the asymmetrical rolling force at the roll gap was studied and related flexibility equations were proposed according to elastic mechanics. Moreover, material mechanics was used to analyze the effects of temperature difference and self-weight on the bending out of the roll gap, and the flexibility equations were constructed. The main factors on bending were summed up, and the bending rule in the rolling could be obtained. In addition practical calculation was made with the production data of ribbon steel from Laiwu Iron ＆ Steel Group Co. Ltd.

冷连轧弯辊力精度改进PSO-SVM预测及补偿分析

为了进一步控制冷连轧弯辊力精度,构建改进PSO-SVM预测模型。利用包含压缩因子的粒子群算法完成支持向量机参数的更高效寻优处理,对回归轧制参数实施反归一化获得弯辊力模型。根据现场实际轧制结果完成预测模型的验证过程。研究结果表明:采用改进PSO-SVM模型获得的预测性能指标在上述优化方法中达到了最低,改进PSO-SVM模型具备最优预测效果。设置可靠补偿后大幅降低了AFC系统工作量,促进了带钢板形效率的显著提升。弯辊力补偿值形成了与弯辊力几乎相同的变化规律,具备优异预测性能。

基于改进的MOGWO高强度钢辊弯成形工艺的多目标优化

为了探究成形参数对高强度钢辊弯件成形质量的影响,并对工艺参数进行优化,提出了一种辊弯成形工艺优化方法。首先,应用LS-DYNA有限元软件模拟LG700高强度钢U型辊弯件的成形过程。然后,通过Box-Behnken响应面设计对高强度钢U型辊弯件进行仿真试验,分析辊弯道次、过弯角、辊站间距和辊缝间距等成形工艺参数以及厚度、法兰高度、圆角半径等几何参数对辊弯件偏差角和纵弓高度的影响,并通过拟合得到偏差角和纵弓高度二者的二阶响应模型。最后,采用改进的多目标灰狼优化(MOGWO)算法对特定尺寸辊弯件进行工艺优化,并通过实例进行验证。结果表明,将优化后的工艺参数用于高强度钢辊弯成形过程中导致其偏差角由0.78°降至0.24°,纵弓高度由1.58 mm降至1.20 mm,成形质量得到提高,满足相关产品的装配精度要求。

龙形轧制轧板的弯曲控制及其对性能影响的研究综述

龙形轧制是一种非对称轧制工艺,通过在异步轧制基础上引入轧辊错位这一新的非对称元素,在增加轧板心部变形量的同时,克服异步轧制导致的轧板弯曲。本文围绕龙形轧制轧板的弯曲控制和其对性能影响的研究进展进行了综述,介绍了新的研究成果并分析了不同研究工作的特点,最后对龙形轧制工艺研究当前存在的主要问题进行了综述,并提出了未来的研究方向。

拉伸孪晶对AZ31镁合金薄板可轧性和组织性能的影响

通过弯曲限宽矫直工艺在AZ31镁合金薄板中预置了拉伸孪晶,随后对原始板材和预置孪晶板材进行轧制,对比分析了初始组织对板材在轧制过程中的塑性变形协调能力的影响,探索了不同轧制压下量对两种板材的组织和力学性能的影响。结果表明:弯曲限宽矫直后板材的强度和塑性都得到了提升,轧制后的原始板材剪切变形带较少。在后续的拉伸试验中,在相同压下量下塑性变形能力也明显提升。

考虑回弹的水平上调式三辊卷板机卷圆精度研究

为提高卷圆成形精度,建立了不考虑回弹与考虑回弹时水平位移量与卷圆半径之间的理论模型。采用ABAQUS软件建立了卷圆成形有限元模型,并通过实验验证了理论模型及有限元模型的可靠性。基于可靠的有限元模型,研究了材料、摩擦力和板厚对卷圆成形精度的影响规律。研究结果表明,不考虑回弹时实验和仿真的成形半径与目标半径之间的误差分别为31.3%和20.7%。考虑回弹后的误差分别降低至2.2%和1.2%;在相同水平位移量下,材料的屈服强度越高,成形半径越大;摩擦力对成形半径的影响较小;板料越厚,成形半径越小。针对不同材料与不同厚度的板料卷圆成形,考虑回弹时的理论模型能够获得更精确的水平位移量,从而提升卷圆精度。

钛焊管连续辊弯成型工艺研究

研究聚焦于Ф168 mm钛焊管的连续辊弯成型工艺,通过数值仿真和实验验证,深入分析了成型速度和成型间距对成型抗力、应力应变的影响。结果表明,在成型速度≤5 m/min、成型间距缩至700 mm时,钛焊管辊弯成型抗力显著降低,成型应力、应变维持在低水平,实现了成型稳定性的显著改善。此外,针对成型过程中的变形情况进行了详细分析,指出边缘拉压作用易导致失稳,产生边浪、鼓包等缺陷。最后,通过数值模拟和试验对比,验证了数值模型的可行性,为钛焊管实际生产提供了指导。

论液压弯窜辊系统的改造及收效

某热轧生产线精轧工作辊弯窜辊系统在日常生产期间存在诸多设备隐患,严重影响了正常的生产作业和产品质量,同时导致了设备损耗和油脂消耗的增大,对生产的正常运行造成极大的影响。为了彻底解决这一问题,满足生产的需要,对精轧工作辊弯窜辊系统进行了全面综合的技术改造,最终取得了理想的效果。

六辊冷轧机弯辊装置制造质量控制关键点分析

文章概述弯辊装置的结构组成和作用,分析影响其制造质量的主要因素,并从设计阶段、加工制造阶段和装配调试阶段3个方面,提出结构优化设计、材料选择、加工工艺控制、装配精度控制和综合性能测试等关键控制点和具体措施,以期为提高弯辊装置制造水平、保障冷轧产品质量提供参考。只有在弯辊装置制造的各个环节实施严格的质量控制和管理,并采用先进的制造技术和检测手段,才能确保弯辊装置的性能和精度满足冷轧生产的高标准要求。

基于机理模型的热连轧板形快速控制技术

热连轧机组板形控制是一项关键的任务,它旨在解决板形变化对产品质量和生产效率的影响。针对热连轧机组板形控制过程中的板形约束变量问题,采用双因素线性插值的方法,在分析弯辊力和窜辊量对板形影响的基础上建立双因素传递系数模型和板形控制空间。首先对板形空间的插值方法进行设计,然后应用到弯辊力和窜辊量对轧制压力的传递系数模型的建立中,求出相应弯辊力与窜辊量对轧制压力的传递系数,这些传递系数可以被视为板形控制的关键参数,利用求出的传递系数基于板形调节建立轧机板形控制空间。通过对板形控制空间的求解,可在板形控制范围内实现板形的快速搜寻和弯辊力、窜动量对板形的快速控制,为热连轧机组的操作提供有效指导。该方法在解决板形控制难题上具有显著的效果,能够提高产品质量和生产效率。未来的研究可以进一步优化传递系数模型和板形控制算法,实现更加精确和自动化的板形控制。

2205/Q420/2205蛇形轧制复合变形规律研究

为研究三层不锈钢复合板在不同工艺参数下轧制复合的变形规律,采用ANSYS有限元软件模拟了2205/Q420/2205三层复合板轧制复合过程,研究了同步轧制、同速异径轧制和同速异径蛇形轧制三种不同工艺下,复合板结合界面等效塑性应变和弯曲曲率的变化规律,分析了不同压下率、初始厚度比和错位量对轧后板形的影响规律,并进行了轧制复合实验。研究结果表明,蛇形轧制通过调整错位量,能有效提高轧后板材界面结合强度并降低轧后弯曲。轧后弯曲曲率随着压下率的增大呈现出先减小后增大的趋势。等效塑性应变随着错位量的增加先增大后减小,轧后弯曲曲率随着错位量的增加逐渐降低,这表明通过适当调整错位量可以使轧后板材同时达到优良的结合强度和平直度。

中南股份50板弯曲率的改善措施及效果

中南股份特轧厂3450 mm生产线,在生产40 mm以下规格50板时,出现较多弯曲现象。产线通过加热炉工艺改善、轧制工艺改善、冷却工艺改善、矫直工艺改善等措施,对轧制过程进行优化,有效降低了50板弯曲率,提高了产品质量。

铝热精轧机工作辊刮板受力情况模拟探讨

采用Solidworks-Simulation有限元模拟软件,计算了热精轧第4机架在穿带阶段,下工作辊刮板受到向下弯曲的卷材头部撞击,所受到冲击载荷的受力变形情况。得出刮板变形量已经超出刮板与工作辊之间的安全距离,刮板变形后与工作辊接触,造成工作辊辊面受损,最终引起卷材表面产生缺陷。