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SME MF98-232
- Using Localized Closed-Loop Force Control To Provide Robustness In Sheet Metal Forming
- standard by Society of Manufacturing Engineers, 11/01/1998
- Publisher: SME
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A system using two drawbeads as actuators coupled with two in-die sensors which are sensitive to sheet forces downstream from the drawbeads demonstrates the usefulness of localized force control. A comparison is made between closing the loop around these sensor outputs and the more traditional approach of closing the loop around drawbead penetration. It is shown that unlike simple position control, closed-loop force control is able to reject typical process disturbances such as changing friction conditions. This makes it possible to maintain consistent punch load trajectories in spite of these disturbances. Furthermore, the dual, independent drawbeads allow the system to compensate for non-symmetrical (with respect to part geometry) disturbances so that process balance can be maintained.