Closed loop control of the friction force. Deep drawing process

K. Siegert, M. Ziegler, S. Wagner

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


When drawing non-axisymmetric sheet metal parts it is necessary to control the flow of material between the lower and upper binder so that the drawn part is free of tears and free of wrinkles. The material flow can be determined by the friction force between the sheet metal and the lower and upper binder. It is possible to determine a friction force curve over the stroke which realizes the desired material flow. The friction force in turn is directly influenced by the blank holder force (BHF). With a closed loop control which uses the friction force as control parameter and the BHF as feedback parameter it is possible to realize the predetermined friction force curve over the stroke, even if the tribological conditions between the sheet metal and the upper and the lower binder will change. This can be carried out by automatically changing the BHF in such a way that the desired friction force and in turn the desired material flow is achieved. To built up a closed loop control, a special die with hydraulically supported segmented binders can be used. This system is able to vary the BHF during the forming process, so that a BHF feedback is possible in the closed loop. To measure the actual friction force as control parameter, a special sensor must be integrated in the die. Such a sensor can be realized with piezo electric load cells.

Original languageEnglish
Pages (from-to)126-133
Number of pages8
JournalJournal of Materials Processing Technology
Issue number1
StatePublished - 1 Nov 1997
Externally publishedYes


  • Blank holder force
  • Closed loop control
  • Friction force


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