Model and analysis of roll force control system for an aluminum cold rolling mill

The subject of this thesis is an analysis of the roll force cylinder control system used on a single stand aluminum cold rolling mill at the Logan Aluminum Company. An analog model of the system is developed using a Laplace Transform and Block Diagram approach. The system is also modeled using ACSL simulation software package and comparisons made between the model and actual system performance. A discrete model is then developed and a digital filter/controller is designed to replace the operation of an analog circuit. The response of these models is also tested using ACSL.

The models are based on Linear Analysis techniques and use as many actual component values as were possible to obtain. Some system parameters such as mechanical dampening, system mass, and hydraulic bulk modulus are difficult to measure and estimated values are used.

There are some variations in the responses of the models. The discrete model with a sampler and zero order hold best simulates the physical operation of the actual system. This model also has the closest match to actual system test data. ACSL simulation of the digital filter/controller indicates that installation of such a filter could be a viable project.