A STUDY ON ROLLING PROCRESS BY USING THE STREAM FUNCTION METHOD

• Main Authors: HSU HUNG-HSIOU, 徐宏修
• Other Authors: Hwang Yeong-Maw
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/04668841907922577172

博士 === 國立中山大學 === 機械工程研究所 === 86 === In this paper, general mathematical models for sandwich sheet rolling andplate rolling by using the stream function method and upper bound theorem wereproposed to investigate the plastic behavior at the roll-gap, such as therelative bonding length between sheets, the flow field of each layer, theextent of plastic regions, etc. The stream functions proposed by this studysatisfy the velocity boundary conditions automatically. The proposed streamfunctions combined by uniform and non-uniform flow fields are able to proposedto simulate non-uniform mechanism type at the roll-gap during sandwich sheetrolling and plate rolling. Firstly, a two-dimensional flow field which satisfies velocity boundaryconditions and has non-uniform velocity distributions was proposed. Employingthis two-dimensional flow field, a mathematical model for sandwich sheetrolling was proposed to analyze the plastic deformation and bonding behaviorof sheets at the roll-gap. The effects of various rolling conditions, such asas the flow stress ratio, reduction, initial thickness ratio, friction factor,etc., upon rolling power, rolling force, thickness ratio at the exit of theroll-gap, the bonding length between sheets, newly generated surface ratio,relative slide distance, the mean contact pressure, etc., were discussedsystematically. Then, using a dual stream function of cylindrical coordinates, amathematical model for plate rolling was proposed to investigate the rigid-plastic boundary and the width spread at the roll gap. The effects of variousrolling conditions, such as roll radius-thickness ratio, friction factorbetween the roll and sheet, the width-thickness ratio, etc., upon the widthspread ratio and rolling force were systematically discussed. Last, a series of sandwich sheet rolling experiments using sandwich sheetof steel, aluminum and copper sheets and plate rolling experiments usingaluminum sheets were conducted. Through the comparison between experimentaland analytical results, it is known that as width-thickness ratio is small,the predicted rolling force and the width spread ratio are larger than theexperimental values.That is because the lateral free surfaces of the sheetwas assumed to be planes which are different from the actual plasticdeformations. However, the analytical results coincide with experimentalresults qualitatively and quantitatively for other working onditions.Therefore, the validity of these models proposed by this study was verifiedand the analytical results can offer knowledge for the design of actualrolling processes.