Improved Design of a Hydraulically Expanded Overhead Cylinder for an Automotive Torsion Beam

Abstract

The design of hydro-bulge molds, able to provide hollow parts with special-shaped cross-sections, is still a pretty complicated task (especially for what concerns the design of the related hydraulic system and its "synchronization"). In the present work, this task is addressed through the introduction of a new type of overhead cylinder hydraulic synchronization system, able to correct automatically any deviation from the optimal process. Using the AMESim software, the displacement synchronization curve of the piston rods of the two cylinders is obtained and it is verified that the system is able to implement an automatic deviation correction function by adjusting the bidirectional servo valve. A mathematical model for the synchronization system is presented, and the transfer function of the closed-loop control system is determined accordingly. The results show that the system response is generated at about 0.1∼0.2 s with the system reaching an equilibrium state at about 0.2 s.