Inhibiting thinning in tube bending by a superposition effect under a boosting movement

Pressure die boost effectively inhibits the thinning in the manufacturing process of aerospace tubes because it can produce a superposition effect of material compensation and friction. This phenomenon attracts lots of scholars. The related research uses the finite element and experimental method to analyze the tube thinning with and without a boost. The effects of boosting velocity and friction on the outer wall thickness of the tube are studied. Results show that frictional force generated by the boost and the material compensation effect combines to resist the outer wall thinning during the bending process. When the boosting velocity is higher than the tube bending linear velocity, the frictional force of the boost generates a specific compressive stress, which weakens the tensile stress during the bending process. In the meantime, the boosting effect transfers the material from the feed section to the bending section, compensating for the thinning of the tube wall during the bending process. A new theoretical model of tube bending and thinning under boost conditions is proposed to explain this coupling effect. The relative error between the new theoretical model and the experimental value is less than 1.5%, and the accuracy is improved by 5.3% compared with the traditional no-boost condition. The research overcomes the poor accuracy of the existing thinning model when fitting to boosted conditions and reveals the boosted effect’s mechanism on tube thinning.