SURFACE TEXTURE TRANSFER IN SIMULATED TANDEM AND TEMPER MILL ROLLING USING ELECTRICAL-DISCHARGE TEXTURED ROLLS

The surface texture of cold reduced steel sheet of the type used for a utomotive applications plays an important role during subsequent proce ssing operations. The paper outlines the results of an extensive serie s of electrical discharge texturing (EDT) experiments aimed at evaluat ing the effect of workpiece rotational speed and flushing method on ro ll texture parameters, specifically surface roughness (Ra) and peak co unt (Pc), in both the axial and circumferential directions. The EDT ri g comprised a DC servo quill assembly fitted with a single graphite el ectrode connected to a dual voltage pulse generator. In addition resul ts are presented from a ''tandem mill'' simulation which gives texture transfer parameters from the EDT roll to the sheet steel (CS1) for a 3% reduction. High speed steel rolls (M2) were used in a four high Sta nat A Mann mill. Finally the effects of overlaying a second ''temper r oll'' texture on the sheet steel are detailed for reductions of 0.5, 1 .0 and 1.5%. micrographs are included of the various textured surfaces together with some 3-D topographical representations.