Research On Hydropiercing-flanging

Hydropiercing-flanging is a new technology to complete the process ofpiercing-flanging with the punch under the support of the hydraulic pressure. As theadvanced preparative technique for tubes, the hydropiercing-flanging technology isdeveloped on the basis of hydroforming and hydropiercing with many advantages interms of less production processes, high efficiency, high precision, good edgequality, collapse reduction, low cost without complexity die.In this paper, hydropiercing-flanging die and punches with conical, spherical,ellipsoidal shape were designed and manufactured to conduct the experiments on thebasis of load calculation. The state of stress and strain of the process ofhydropiercing-flanging was analyzed with ABAQUS/Explicit. The influence of theflanging coefficient, pressure and punch shapes on the flange edge quality, the depthof the collapse, the flange height, the flange thickness and the flange shape accuracywas researched combining experiments and simulations.The results show the material around the flange is of bending deformation inthe process of hydropiercing-flanging. The smaller the flanging coefficient is, themore severity of the crack degree in the flange edge. When the flanging coefficientis greater than0.6, good flange edge quality received under lower or higher internalpressure. When the flanging coefficient is no less than0.6, the lower the internalpressure is, the better the flange edge quality is. When the internal pressure is lessthan120MPa, the depth of the collapse and flanging height are decreasing with theinternal pressure. Under the pressure of50MPa, the flange shape is of a certain taperpunched by all the three punches. When the pressure is greater than80MPa, theflange wall is vertical punched by the conical and ellipsoidal punch but archpunched by the spherical punch, which affects the flange shape accuracy. The highthe internal pressure is, the more obvious the arch is. The depth of the collapse is thelargest punched by the spherical punch and the smallest punched by the conicalpunch. When the flanging coefficient is less than0.6, no obvious rules of the flangedimensions are found and the flange shape accuracy is badly for the material aroundthe flange is severely warping under high internal pressure. Better flange edgequality could be received with the ellipsoidal punch under80MPa considering theflange dimensions and shape accuracy.