Press-Bending Of The Thin-Walled Tube With Internal Pressure

Tube press-bending process with internal pressure is a technique that press-bends the tube that is sealed and filled with liquid. This process is high efficiency and low cost, and especially suitable for the thin-walled tube and the variable curvature tube.Numerical simulation had been conducted for tube bending with internal pressure, the outer diameter of the tube was 55mm and the thickness was 1.75mm. The influence parameters such as relative bending radius and internal pressure had been researched. The results show that, with an increasing internal pressure, non-circularity of the tube decreases, and the tendency of thickness thinning on inner and out side of the tube increases. And with an decreasing relative bending radius, non-circularity of the tube increases, the tendency of thickness thinning on outer side of the tube increases, and the thickness thickening of the tube increases, too.The stress and strain of the special spots have been analyzed according to the results of simulations, the results show that, when the internal pressure was 18MPa, the axial compressive stress was less than the press-bending without internal pressure. And the relations between the non-circularity and the internal pressure, the relative bending radius have been established.The experiments were conducted with the low carbon steel tube with 55mm in outer diameter and 1.75mm in thickness. The results of the experiments coincided with the simulation. Compared with the effect of the different parameters on forming process, the rules had been confirmed exactly.In this dissertation, a typical variable curvature thin-walled tube has been simulated. The press-bending process with internal pressure decreased the difficulty of the post forming, and increased the percents of the sound products.