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Title: Analysis of product shape in tension levelling and plate stretching processes
Author: Morris, J. W.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2000
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The end use of steel and other metals despatched in coiled form from Corus can vary from car autobody panels to sheets in office furniture constructions. For some customers, it is important, and sometimes critical, that the as-coiled material is geometrically flat when de-coiled, such that downstream processing can be performed by the customer. Undesirable shape defects can be introduced into the material at the cold mill owing to poor rolling conditions being present and other applicable factors, thus generating the strip and plate defects of wavy edge and centre buckle. These shape defects are unacceptable to some customers, and must be removed prior to despatch. The only methods available to remove these defects and guarantee flat material in strip and plate are tension levelling and plate stretching. A review of the previous work competed on these processes is presented, including many aspects of the applicable theoretical and empirical work studied. A series of finite element models was developed throughout the course of the project. The emphasis in these models was on product shape, both pre and post levelling, and the mechanism by which product shape is removed (and controlled) by the levelling and stretching processes. Statistical models are also presented, in the form of a designed factorial analysis, which attempt to address the problem of flatness inconsistency in tension levelling. Results from the study have found that the tension levelling process generates a characteristic residual stress distribution cross-width, with the initial distribution modified in magnitude only. Statistical studies also found that many interactions occur between process parameters, particularly in the consideration of final flatness and, hence, shape removal. In the plate stretching process, it was found that shape defects (manifest in the form of waves) are removed by preferentially elongating shorter longitudinal fibres, with a complex stress concentration present characteristic of the initial geometry of the defect.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (D.Eng.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available