充压镦形技术原理及应用

In the forming process of hollow parts by expansion deformation mode, the plastic deformation is totally driven by internal pressure, and there are difficulties in excessive high pressure, wall thickness thinning and low production efficiency, so the hydro-forging technology was proposed, and its idea of forming was opposite to expansion forming. The principle is to form hollow parts with variable sections by conducting section compression for tube blank in virtue of the support of internal pressure. And the mechanical principle that the in-plane compression instability stress increases under normal force support was applied. The results show that the internal pressure is liberated by the change of deformation mode, and the internal pressure only plays an auxiliary supporting role, and the required pressure is below dozens of megapascal. In addition, the material always deforms under the condition of three-way compressive stress in the hydro-forging, which avoids the problems of wall thickness thinning and cracking in the expansion deformation mode. Finally, the technical advantages of this process in practical application were demonstrated through forming a B-pillar of car body.