Suppressing wrinkles in thin-walled dome parts: A novel deep drawing method with active stress control

Abstract

The occurrence of wrinkling defects in deep drawing thin-walled dome parts is primarily attributed to circumferential compressive stress. With a decrease in the thickness-to-diameter ratio, preventing wrinkling becomes increasingly challenging during the forming process. This study proposes a novel deep drawing method that effectively suppresses wrinkles in thin-walled dome parts through the utilization of a local reverse bulging tool for active stress control. An analytical model is developed to describe this novel deep drawing method, enabling analysis of the radius variations in the reverse bulging area and the corresponding reverse bulging force. Numerical simulations are carried out to investigate the effect of the reverse bulging loading path on the stress-strain distribution. Furthermore, experimental trials are performed under various loading conditions to explore the impact of loading paths on forming defects and thickness distributions of the formed parts. The findings indicate that the radius of rigid tools and the reverse bulging force play pivotal roles in achieving the desired reverse bulging effect. As the punch stroke increases, the radius of the reverse bulging area decreases, while the reverse bulging force exhibits a pattern of initial increase followed by a subsequent decrease. By employing an appropriate reverse bulging loading path, the circumferential stress at the reverse bulging area transitions from compressive stress to tensile, effectively suppressing the occurrence of wrinkles. This research provides valuable experimental guidance for implementing the novel deep drawing process for dome parts.