Advanced Springback Compensation Strategy through elimination of avoidable elastic strain energy

Abstract

The stamping of dimensionally accurate sheet metal body components still represents a huge challenge in the automotive industry. This is partly caused by the multi-stage production process which complicates the design of an appropriate compensation strategy dramatically. A key prerequisite of an appropriate compensation strategy is to eliminate any undesired influence of elastic energy being potentially induced when closing the blankholders in the several operations throughout the production process. Here, a universally applicable compensation strategy is presented which fulfils this requirement thoroughly; by applying this process, the involved strain energy is reduced to a minimum due to proper part position in all operations. Technically this compensation strategy is achieved by, first, simulating all operations of the stamping process individually, second, by individually calculating the springback after each operation and, third, by accumulating the calculated deviation vector fields for each operation appropriately, which are then used for springback compensation. The process is time and cost effective and the required efforts are moderate even for complicated multistage stamping operations.

Holistic springback compensation procedure

“…In a next step, the single forming operations are simulated separately and without the influence of unwanted deformations during blank holder closing and the respective springback is calculated. The single springback results are then summed up using the Advanced Strategy [17]. After that the forming operations are adapted to the arriving part, as specified in the Improved Strategy [16].…”

“…A combination of the Advanced Strategy [17] and the Improved Strategy [16] is used here as compensation strategy. The optimized Physical Scaling Approach [14] is used for scaling the drawing operation and the physical compensation method [12] is used for compensating deviations normal to the sheet surface.…”

“…In addition to a dimensionally accurate part at the end of the process, this strategy also makes it possible to achieve a stable part position when inserting the parts into the subsequent operation. Another modified compensation strategy that emerged from the first mentioned is the Advanced Springback Compensation Strategy (Advanced Strategy) [17].…”