TY - GEN
T1 - The frictional force between slug and die in shear cutting after material separation
AU - Stahl, Jens
AU - Pätzold, Isabella
AU - Bosch, Lucas van den
AU - Kindsmüller, Alexander
AU - Golle, Roland
AU - Volk, Wolfram
N1 - Publisher Copyright:
© 2021 Trans Tech Publications Ltd, Switzerland.
PY - 2021
Y1 - 2021
N2 - Frictional forces in sheet metal blanking are central in different aspects, e.g. in wear prediction, validation of simulation models or in so called slug pulling. The latter is a phenomenon where the slug is pulled out of the die by the punch after the sheet metal is separated. This leads to process disturbances reaching from a blocked belt feeder up to severe tool damage caused by the simultaneous cutting of the slug and the sheet metal strip. A sufficiently high frictional force between the slug and the die prevents this effect. Despite its importance, this force and its causes have not yet been investigated in detail. A method was developed in this paper to measure the frictional force between slug and die. A shear cutting tool with an integrated piezoelectric load cell and an inductive position sensor was used on a stamping press to cut sheet metal made of CuSn6 (R350, thickness 1 mm). The die clearance, the punch edge radii and the lubrication conditions were varied. A larger die clearance resulted in a lower frictional force while a larger punch edge radius increased it significantly. Lubrication reduced the frictional force, especially for small die clearances. Finally, the cause of the frictional force was investigated by identifying the relevant springback modes of the slugs. This was carried out by correlating the slugs' deflection, oversize, and clean cut height with the frictional force. Especially the slug oversize, i.e. the difference between the slug's diameter and the die's inner diameter, revealed a strong correlation. Calculations showed that the deformation in radial direction is the main cause of the frictional force between slug and die. It suggests that the slug oversize is a good measure for the magnitude of the frictional force.
AB - Frictional forces in sheet metal blanking are central in different aspects, e.g. in wear prediction, validation of simulation models or in so called slug pulling. The latter is a phenomenon where the slug is pulled out of the die by the punch after the sheet metal is separated. This leads to process disturbances reaching from a blocked belt feeder up to severe tool damage caused by the simultaneous cutting of the slug and the sheet metal strip. A sufficiently high frictional force between the slug and the die prevents this effect. Despite its importance, this force and its causes have not yet been investigated in detail. A method was developed in this paper to measure the frictional force between slug and die. A shear cutting tool with an integrated piezoelectric load cell and an inductive position sensor was used on a stamping press to cut sheet metal made of CuSn6 (R350, thickness 1 mm). The die clearance, the punch edge radii and the lubrication conditions were varied. A larger die clearance resulted in a lower frictional force while a larger punch edge radius increased it significantly. Lubrication reduced the frictional force, especially for small die clearances. Finally, the cause of the frictional force was investigated by identifying the relevant springback modes of the slugs. This was carried out by correlating the slugs' deflection, oversize, and clean cut height with the frictional force. Especially the slug oversize, i.e. the difference between the slug's diameter and the die's inner diameter, revealed a strong correlation. Calculations showed that the deformation in radial direction is the main cause of the frictional force between slug and die. It suggests that the slug oversize is a good measure for the magnitude of the frictional force.
KW - Blanking
KW - Friction
KW - Slug Pulling
UR - http://www.scopus.com/inward/record.url?scp=85120052153&partnerID=8YFLogxK
U2 - 10.4028/www.scientific.net/KEM.883.285
DO - 10.4028/www.scientific.net/KEM.883.285
M3 - Conference contribution
AN - SCOPUS:85120052153
SN - 9783035716931
T3 - Key Engineering Materials
SP - 285
EP - 293
BT - Sheet Metal 2021
A2 - Merklein, M.
A2 - Hagenah, H.
A2 - Duflou, J.
A2 - Fratini, L.
A2 - Micari, F.
A2 - Martins, P.
A2 - Meschut, G.
PB - Trans Tech Publications Ltd
T2 - 19th International Conference on Sheet Metal, SheMet 2021
Y2 - 29 March 2021 through 31 March 2021
ER -