Experimental and numerical studies on the formability of TB5 titanium sheet in rubber cold forming

Abstract

Titanium alloys are often used in aircraft manufacturing. Titanium sheet exhibits low formability and high springback at room temperature, and this causes significant challenges with conventional forming methods. In this study, the phenomena and mechanisms of the formability of TB5 titanium alloys in rubber forming were investigated. It was found that rubber forming was effective for TB5 titanium sheets. Wrinkling in rubber forming was controlled by the side blankholder. The effects of the design parameters of the side blankholder on wrinkling were studied. A typical part was used to investigate the rubber cold forming of TB5. The largest height of the wrinkle became smaller with the increase of the forming pressure, while the hardness of rubber had little effect on the wrinkling. In order to eliminate the wrinkles completely, a wedge was introduced to increase the forming pressure on the shrink flange. Using the wedge, the forming pressure was increased a lot, and the wrinkles were flattened. Springback was controlled by die compensation. Aging treatment was used to increase the strength and part accuracy. After the aging treatment, the internal stress in the cold forming was released. The springback of the flange was corrected.