The Virtual Rolling Mill – Enhancing Product Development and Commissioning

Achenbach supplies worldwide with first-class customized rolling mills and machinery for the manufacturing of flat-rolled products from non-ferrous metals. In order to fulfil the customer-specific production requirements, Achenbach developed a wide variety of options for specific subjects. The control of the strip quality parameters like flatness or thickness in the rolling process is a key performance index.An increase of computation power in the field of industrial computers gave a chance to develop more complex model based control algorithms, which led to a significant improvement of the strip quality. In addition it gave an impulse for the development of a comprehensive mathematical model of the rolling mill.This paper will present the general virtual Achenbach Rolling Mill which is a digital representation of the rolling process in general and the behavior of the major actuators in the rolling process in detail. The behavior of drives, strip-tensions, and roll-gap is simulated in a multi-variable real-time environment. In the same environment the OPTIROLLi3®- model based controls can interact with the virtual machine. A vast number of challenges of the real rolling situation can be demonstrated by working on this ‘mill simulator’ and improved solutions are developed taking advantages from this platform. As the virtual machine allows all kinds of virtual testing without scrapping ‘real material’ a wide range of applications is possible for this virtual rolling mill. Some results from the SIL (software in loop) simulation will be presented for better clarity.

Application of Dynamic Deadband Eccentricity Filter in GM-AGC System

The problem of roll eccentricity has become one of important factors to affect the quality of strips as downstream industries require improvement of the strip quality. Reducing thickness control precision as little as possible is incompatible with restraining roll eccentricity perturbations on the requirement of the deadband size for the deadband drift method (DDM) with fixed deadband width. Therefore, the GM-AGC system in hot finishing mill of an aluminum plant uses the dynamic deadband eccentricity filter (DDEF) whose deadband width varies with the amplitude of the roll eccentricity signal. The operating principle of DDEF was introduced according to the characteristic of roll eccentricity signal. Based on the theory of DDEF, simulation was carried out. Comparing with DDM, the simulation result shows that DDEF can keep a balance between less lowering thickness control precision and restraining roll eccentricity perturbations on the requirement of the deadband size. Moreover, the deadband width of DDEF is capable to fit the variations in the frequency and amplitude of the synthetic roll eccentricity signal to restrain the misoperation of GM-AGC system.

Research on CSP Work Roll Defect Causes and Improvement Measure

It was analysed that the causes for the poor wear resistance of roller, fracture of roller and the surface of the roller flaking off were researched. Introducing CSP plant carried through technical and improved works about work roll material and using system in order to improve strip quality and decrease producing costs. It’s effective to resolve wear and breakage and spalling of the work roll and improve profile control and so on.

Study on Control Strategy of Shape Set up System for HSM

Shape Set Up (SSU) system is the key technology for Hot Strip Mill (HSM). Precise SSU system is applied to improve the strip quality for HSM. The function of SSU, Setup and Feedback, is introduced. The main mathematic model of strip profile is set up. SSU system strategy is studied of a certain domestic 1700mm HSM. The SSU system is carried out in produce and the measurement data show that strip flatness deviant and strip profile deviant could be controlled in target scope. The study has set a sound base to improve the setting accuracy and develop SSU system for HSM further.

Coupling Dynamic Model and Control of Chatter in Cold Rolling

The dynamic model of 4-h mill, which couples with the rolling process model, the mill roll stand structure model, and the hydraulic servo system model, is built by analyzing the vibration process of cold rolling. By linearization, the multiple input multiple output linear transfer function matrix model of single stand 4-h cold mill system is obtained. With the consideration of strip quality, the model of strip thickness control system is established in a simplified form. Meanwhile, the robust controller based on quantitative feedback theory is designed for the gauge control model. A comparison with PID controller shows that the controller has better disturbance attenuation performance for parameter uncertainty and external disturbance.

Study on Roller Eccentricity Compensation in a Cold Mill

With the increase request of strip quality, the roller eccentricity has become the important factor of influencing product quality. On the practical model of Cold-rolling Mill of 300, this paper establishes eccentricity compensation control practice of Cold-rolling Mill of 300 which applies wavelet transform method. Based on mufti-resolution decomposition of roll force signal by use of wavelets, eccentricity signals are separated from disturbances and noise,and self-optimization is employed to real-time control the roller eccentricity. The results show that the method is effective.

The Integrated Robust Control of Interstand Strip Tension for Tandem Cold Rolling Mill

We describe an integrated tension controller design for a tandem cold rolling mill in steel plants. To achieve stable rolling and ensure strip quality, it is very important to control the tension of the cold rolling mill. Previous researches examined only the operation of a single stand. But it is not sufficient to examine the operation and effect of whole stands because the operation is wholly interdependent. To solve the problem, this paper proposes an integrated control strategy for tension control of tandem cold mill, the full stand model for the tension system of a tandem cold mill is built, and the interaction of all the stands is analyzed. Then applying the method of μ-synthesis design a integrated robust tension controller. Simulation with the practical data proves the integrated robust tension controller can achieve more robust performance than that of typical industrial approach.