In-process measurement of springback in tube rotary draw bending

Rotary draw bending of tubes allows repeatable and accurate manufacturing with narrow bending radii and high production rates, thanks to modern CNC controlled electrical machines. However, springback still represents one the main issues especially in small production batches or when the geometrical and mechanical properties of the raw profiles are not constant within the batch. In-process inertial measurements may allow the close-loop process control of the bending angle and, potentially, offer the possibility to compensate the springback by a real-time tuning of the bending. The paper focuses on a newly developed in-process measurement technique and presents an assessment of in-process inertial springback measurements. The springback of bent tubes is investigated as a function of the measurement gauge position and of the cross-section strain distribution along the bend.