Title

Roll Texturing by Electronic Discharge Texturing "EDT"

Roll Texturing by Electronic Discharge Texturing "EDT"

Authorship

WITZLEB, VOLKER

WITZLEB, VOLKER

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DOI

10.5151/2594-5297-LA3295

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Abstract

Automobile manufacturers demand a certain surface roughness on the sheet in order to have smooth deepdrawing and painting operation. Deepdrawing requires a coarse structure whereby oil pockets are formed to prevent the metal sheet from 'cold welding' to the die shoe tool. Painting requires a fine structure to achieve a surface finish with a high quality; on the other hand painting requires a defined roughness to have an excellent cling to the sheet. These surfaces can be achieved by texturing the rolls with an Electronic Discharge Texturing Machine. Process: A generator switches on the erosion impulse. The conducting particles in the dielectric oil form a dipolar bridge which produces intermittent charge of current to be passed onto the roll. A bowl shaped particle is brought to its melting point and a gaseous by product bubble is formed at the discharge duct area. After the erosion impulse is completed, the discharge duct collapses and the melted particle is expelled. A trough-shaped surface structure remains. Result: Surface qualities with an average coefficient of roughness Ra between 0.5 and 15.0 micrometers and 240 to 25 peaks per cm (Pc) can be achieved

Automobile manufacturers demand a certain surface roughness on the sheet in order to have smooth deepdrawing and painting operation. Deepdrawing requires a coarse structure whereby oil pockets are formed to prevent the metal sheet from 'cold welding' to the die shoe tool. Painting requires a fine structure to achieve a surface finish with a high quality; on the other hand painting requires a defined roughness to have an excellent cling to the sheet. These surfaces can be achieved by texturing the rolls with an Electronic Discharge Texturing Machine. Process: A generator switches on the erosion impulse. The conducting particles in the dielectric oil form a dipolar bridge which produces intermittent charge of current to be passed onto the roll. A bowl shaped particle is brought to its melting point and a gaseous by product bubble is formed at the discharge duct area. After the erosion impulse is completed, the discharge duct collapses and the melted particle is expelled. A trough-shaped surface structure remains. Result: Surface qualities with an average coefficient of roughness Ra between 0.5 and 15.0 micrometers and 240 to 25 peaks per cm (Pc) can be achieved

Keywords

roll texturing; EDT; spark erosion; surface roughness; WALDRICH SIEGEN

roll texturing; EDT; spark erosion; surface roughness; WALDRICH SIEGEN