Joint project Hochpräzisionswalzen

 

Enhancement of width and thickness tolerances of metallic strips by using a piezo-electric control system for roll gap adjustment of a tandem mill

 

Motivation

Thin metallic strips are used in various technological fields, such as telecommunications or high-frequency technology. With the miniaturization of devices in which these strips are integrated, the demand for manufacturing precision of the strips also increases. Especially in increasingly faster rolling mills, the dynamics of electromechanical or hydraulic roller adjustment actuators are insufficient to respond to high-frequency irregularities in the strip and disturbances. In collaboration with the Institute of Metal Forming at RWTH Aachen University, approaches are therefore being investigated to improve the thickness tolerances of cold-rolled metallic strips by employing control engineering methods in combination with precise and highly dynamic actuation.

 

Project Goals and Methods

The objective of the project is the control of the thickness and width of thin and narrow metallic strips. In the first phase of the project, a conventional rolling mill was equipped with piezoelectric stack actuators, which were used for highly precise roll stand adjustment. These piezoelectric actuators are integrated into a model predictive control system, utilizing fast rolling models, to find an optimal and highly dynamic actuator trajectory. In the second phase of the project, in addition to thickness tolerances, the tolerances of the width are also considered. This is achieved by extending the existing models to a combined thickness and width model, which is then utilized in the model predictive control. To adjust the additional control variable, the strip is processed in two consecutive rolling passes with individually optimized settings. To further improve the process, data is continuously recorded, evaluated in real-time, and used to enhance the models. This allows for the detection of parameter variations that affect product quality.

 

Innovations and Perspectives

The research in the field of cold rolling aims to investigate methods and pathways that can lead to further improvement in the dimensional tolerances of metallic strips. Through online data acquisition and analysis, it becomes possible to dynamically learn machine and process parameters in real-time and provide them to an adaptive control system. In combination with expert knowledge of the process, the correct inferences can be drawn from the data, thus transitioning from purely machine control to quality control.

 

Project partner
RWTH Aachen University, IBF - Institute of Metal Forming