3D-SURFACE PARAMETERS AND THEIR APPLICATION ON DETERMINISTIC TEXTUREDMETAL SHEETS

In sheet metal forming the surface structuring of steel sheets is appl ied by several methods during skin pass rolling. The function of the s urface is to lower the friction in the forming process and to achieve a high glossiness of the finished product after painting. In the past, two technologies have been developed to texture the rolls with a thre e dimensional deterministic structure: the laser texturing surface and the electron beam texturing surface. Due to their deterministic featu re such topographies are totally different from those usually applied and thus, they require adequate methods to characterize them. Appropri ate parameters can be derived from the so called mechanical-rheologica l model which is about to be developed at the LFT. Basic parameters ar e the material area ratio as well as the open void area ratio and the closed void area ratio. In the present paper the theoretical backgroun d of the new surface parameters as well as the method of measurement a nd the program SAM (Surface Analysis Module) will be explained. To dem onstrate the capabilities of the method, different kinds of surfaces a re characterized using the newly developed parameters. For practical u se in industrial application the change of the surface in a cold rolli ng process for the manufacturing of steel sheets was investigated. It can be shown by the new parameters that there is a strong influence of the mill's wear process on the structure of the rolled steel sheet. A nother application concerns the surface deformation in a deep drawing process. (C) 1998 Elsevier Science Ltd.