The frictional force between slug and die in shear cutting after material separation

Jens Stahl, Isabella Pätzold, Lucas van den Bosch, Alexander Kindsmüller, Roland Golle, Wolfram Volk

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Scopus citations

Abstract

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.

Original languageEnglish
Title of host publicationSheet Metal 2021
EditorsM. Merklein, H. Hagenah, J. Duflou, L. Fratini, F. Micari, P. Martins, G. Meschut
PublisherTrans Tech Publications Ltd
Pages285-293
Number of pages9
ISBN (Print)9783035716931
DOIs
StatePublished - 2021
Event19th International Conference on Sheet Metal, SheMet 2021 - Virtual, Online
Duration: 29 Mar 202131 Mar 2021

Publication series

NameKey Engineering Materials
Volume883 KEM
ISSN (Print)1013-9826
ISSN (Electronic)1662-9795

Conference

Conference19th International Conference on Sheet Metal, SheMet 2021
CityVirtual, Online
Period29/03/2131/03/21

Keywords

  • Blanking
  • Friction
  • Slug Pulling

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