Development of dynamic loading system for sheet metal hydrodynamic deep drawing and its application

The loading paths of cavity pressure and blank holding force (BHF) are the key parameters immediately related with the forming quality in hydrodynamic deep drawing process. Aiming at the issues of single loading trajectory and low liquid pressure in the passive-pressurization model, which can not satisfy the need of the complex structural components and high strength materials, a dynamic loading method employing closed-loop control technique to realize the real time adjustment of cavity pressure and BHF is presented. The controllable blank holding system and high pressure & pressurization device are designed, and the control system based on upper and lower computers is applied to regulate punch velocity, BHF and cavity pressure, which can change in real time according to assigned craft curves. The process experiments conducted on the dynamic loading system implement the integral and precision forming of a typical stainless steel part with complex features, and the test parts under dynamic loading paths have good surface quality and high forming precision. The results indicate that the dynamic loading technology can implement complicated loading paths and partial high pressure, which are propitious to form complicated structural components and high-strength materials.