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Title: Strip position measurement and control for consistency of zinc coating in hot-dip galvanising lines
Author: Price, M.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1998
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The stability of the strip between the gas knives during the wiping stage of hot-dip galvanising is critical for consistent zinc coating mass. Variation in this coating mass can result in a product that does not meet customer requirements. A significant saving can be made on the amount of zinc used and the quality of the product will be enhanced if the tolerances on the coating mass are tightened. A dynamic distributed parameter model is developed for understanding strip vibration and design of a controller for stabilisation, and is implemented in the simulation package SIMULINK. The model can be stimulated at any point by a force input and the displacement and velocity of any point can be measured. A physical model has been developed, for the purposes of validation and for test purposes, and is a scale representation of the critical part of the hot-dipping process. The computer model and physical models can be matched by use of appropriate stimulation signals and the use of genetic algorithms. The matched models show a good correlation and the confidence in the model is high. Currently air cushions and touch rolls are used to stabilise strip and the effect of these systems on the strip can be shown using both the computer and physical models. The computer model is used to develop a control scheme using the techniques of root-locus and Nichols charts. The response of the controlled system is analysed using Bode plots and step responses and shown to be an improvement on the uncontrolled system. The actuator, sensor and electronics for physical realisation of the designed control scheme are also given. The work presented here shows the method of producing a control scheme for improving the stability of strip steel within hot-dip galvanising lines.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (D.Eng.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available