A new adaptive bending method using closed loop feedback control
(Department of Engineering Design and Materials, Norwegian University of Science and Technology (NTNU),
Richard Birkelands veg 2B, N-7491 Trondheim, Norway)
Richard Birkelands veg 2B, N-7491 Trondheim, Norway)
Abstract: As the competition from companies in low cost countries increases, the need for more automated production which reduces labour cost while improving product quality is required. A new rotary compression bending set-up with automated closed-loop feedback control is thus being developed. By transferring in-process measurement data into an algorithm for predicting springback and bend angle prior to the unloading sequence, the dimensional accuracy is improved. This work focuses on the development of this steering model. Since the method used does not increase cycle time, it is attractive for high-volume industrial applications. More than 150 bending tests of AA6060 extrusions were conducted to determine the capability of the technology. The results show that by activating the automated closed-loop feedback system, the dimensional accuracy of the bent parts is more than three times better than that obtained by traditional compression bending. Since the steering model permits the direct use of additional process data, such as instant wall thickness and cross sectional distortions, it is believed that extension of the measurement capabilities would improve the accuracy of the methodology even further.
Key words: adaptive bending; closed-loop feedback; dimensional accuracy; springback; aluminium; extrusion