柔性辊缝轧机复杂板形缺陷控制策略研究

Analyzing the control characteristic of the shape control actuators exactly is very important as it is key to complex shape defects control of wide and thin strip. The computation accuracy of conventional strip shape mechanism solution methods such as analytical model is too low due to too many assumptions such as roll bearing load and rolling force distribution. The mostly concerning point of which is the mechanical characteristic of shape control actuators, however, strip shape reflects the synthesis characteristic of both rolling mill and work piece. The loaded gap contour of the most widely used flexible roll gap mill can be continuously and controllably regulated in a large range. Taking the typical CVC and CVC plus rolling mill as the research object, and the mill-strip unified shape regulating thoery as the breakthrough point, the influence of strip characteristic on shape will be researched based on the crown inherent thoery and the roll system elastic deformation thoery. The inter-pass shape coordination control model along the whole strip width will be established. In the same time, exactly analyzing the influence on mill-strip coordinatrion deformation law and the bearing load distribution of equipment, process and control parameters using the entire coupling simulation model of rolled piece, backup roll, work roll and the rolling mill bearings. The shape control matix model of the whole strip width of each pass will be obtained. The backup roll bearing load testing platform of four-high experiment mill is developed, the numerical simulation model and theoretical model will be verified and improved according to the experimental data. Then the complex shape defects control strategy will be provided. The research will provide technical support and theory basis for rolling bear working mode and precise controlling of complex flatness defects.

精确解析板形调控机构的调控特性，是实现宽薄规格板带材复杂板形缺陷合理控制的关键。现有板形机理仿真模型假设条件多，且关注的多为板形调控机构的机械特性，而板形反映的是轧机和轧件的综合特性。柔性辊缝轧机可使承载辊缝形状在较大范围内连续可控变化，本项目以典型的CVC和CVC plus轧机为研究对象，以轧机轧件统一板形调控理论为切入点，基于凸度遗传理论和辊系弹性变形理论，研究轧件特性对板形的影响规律，建立道次间轧件全宽度板形协调控制模型；同时采用轴承-辊系-轧件整体耦合数值模拟模型，精确分析设备、工艺和控制参数对轧机轧件协调变形规律和轴承载荷分布的影响，建立各道次轧件全宽度板形调控系数模型；开发实验轧机轴承载荷测试平台，利用实验数据对数值模拟和理论模型进行验证、完善；进而制定宽薄板带材复杂板形缺陷控制策略。项目可为该类型轧机的宽薄板带材复杂板形缺陷控制和轴承服役状态优化提供理论依据。

为了衡量轧机全辊缝内的板形控制特性，在轧机横向刚度理论的基础上，定义了轧机全辊缝横向刚度，并对其影响因素进行了分析；在解析板形刚度理论的基础上，利用广义板凸度、全辊缝横向刚度将板形测控模型扩展至轧件的全宽度；利用ANSYS/LS-DYNA软件，建立了耦合支撑辊轴承箱、圆柱滚子轴承、辊系与轧件的四辊板带实验轧机整体变形模型，对各种工况轧制过程的板凸度和轴承载荷情况进行了对比分析；自主设计了四辊板带实验轧机支撑辊组合式轴承力-温综合测试装置，对下支撑辊各列轴承的径向载荷分布、轧后轧件横向厚度和板凸度进行了测试；利用边界元法模型对采用四列圆锥滚子轴承的二辊轧机进行了轴承载荷分布分析；对四辊CVC轧机轧辊磨损后期的板形控制特性进行了分析，并制定了该工况下四分之一浪的有效控制策略；对四辊CVC轧机的单边浪控制策略进行了研究，证明了辊系倾斜和非对称弯辊在控制因不同因素导致单边浪的控制效果；考虑力的分布、轧制规程、综合辊形对轴向力的影响，以轴向力最小化、轧机刚度最大化和辊间压力均匀化为目标，对四辊CVC轧机的辊形配置策略进行了研究；针对某双机架可逆冷轧机组启车过程断带事故严重的问题，全面研究了其启车实现过程，发现其静态建张过程在入口机架处产生的减薄区，是导致后续过程张应力异常波动进而断带的原因，在此基础上优化了启车控制策略；针对冷轧机加减速过程中厚度超差的问题，考虑油膜厚度和摩擦系数提出了新的厚度补偿控制策略。