Analysis of Process Control of Roller Leveling by Utilization of a FE Model with Integrated Closed-loop Control Structures

轧辊调平对于消除平面缺陷和残余应力是必不可少的，例如平面产品。与其他制造技术相比，矫直机的设置主要由经验决定。然而，越来越严格的公差和新材料显示出这种简单方法的局限性。因此，提高对这一过程的理解和更好地控制是至关重要的。对整平辊的设置进行闭环控制将是一个明智的解决方案。但是所有现有的方法都有三个主要的缺点：1)测量得到的平面度会导致控制系统中的大量死区时间。其结果是，带钢的开始将不会被适当地平整。2)工件性能的变化（屈服应力，带材厚度和初始曲率）在通过整机之前不会被检测到。没有实用的测量技术来测量矫直机无张力出口受重力影响的残余曲率。特别是最后一个方面，使得目标性能（曲率、残余应力）与实际测量数据（轧辊处的力和力矩、带材挠度）之间的影响难以进行实验研究。因此，一个有限元模型应使用来创建一个理想的环境（例如，没有重力对曲率的影响）来分析这些影响。此外，在有限元仿真中实现闭环控制系统创建了一个虚拟测试不同控制系统的工具。在项目后期，通过实际实验对闭环控制系统进行了验证。已经进行的研究表明，可以在加工前和加工过程中利用工艺参数（例如力和力矩）来识别与预期工件性能的偏差。预先创建的模型值可以为机器提供正确的设置。因此，长期目标是开发一种新的控制概念，利用在机器灌装期间已经开始的过程数据。这可以减少投资和维护成本，减少浪费的材料，并提高后续加工线的可用性。

Roller leveling is essential to remove flatness defects and residual stresses of e.g. flat products. In contrast to other manufacturing technologies the setting of the leveler is mostly determined by experience. However, stricter tolerances and new materials are showing more and more the limits of this simple approach. Therefore it is vital to gain an improved understanding and to develop a better control of the process.A closed-loop control of the setting of leveling rolls would be a sensible solution. But all existing approaches have three major disadvantages:1) A measurement of the resulting flatness leads to a significant dead time in the control system. As a consequence the beginning of the strip will not be leveled properly.2) Variations in the properties of the work piece (yield stress, strip thickness and initial curvature) will not be detected before they have passed the whole machine.3) No practical measurement techniques are available to measure a residual curvature influenced by gravity in a tension free outlet of the leveler.Especially the last aspect makes experimental research of the influence between target properties (curvature, residual stresses) and real measurement data (e.g. forces and moments at the rolls, deflection of the strip) difficult to conduct. Therefore, a FE model shall be used to create an idealized environment (e.g. without influence of gravity on the curvature) to analyze these influences. Additionally implementing closed-loop control systems in the FE simulation creates a tool to test different control systems virtually. At a later stage of the project the closed-loop control system is tested by practical experiments.Already conducted research has shown that process parameters (e.g. forces and moments) can be utilized before and during the process to identify deviations from the expected work piece properties. Model values created beforehand can then provide the right settings for the machine. Thus, the long term target is to develop a new control concept that utilizes process data starting already during the filling of the machine. This can lead to reduced investments as well as maintenance costs, less wasted material and a higher availability of the subsequent processing line.