B. Meng

Development of thermal deep drawing system with vacuum environment for difficult-to-deformation materials

Abstract The thermal deep drawing process with vacuum environment was put forward to solve the problems in the forming of the high strength and difficult-to-deformation sheet metals such as difficult to form under normal temperature and easily to be oxidized at high temperatures. The vacuum hot drawing system was discussed and developed based on the integration of vacuum heating technology and variable blank holding force (BHF) system, which consisted of mainframe system, hydraulic system, vacuum system, heating system, water-cooling system, air-cooling system and computer control system, and the key parameters such as temperature, BHF and punch velocity were regulated in real time using PID closed-loop control technique. The deep drawing test of 2.0 mm-thick molybdenum sheets with temperature of 870 °C and vacuum degree of 10 −2 Pa was conducted on the system, and the molybdenum crucible with limiting drawing ratio of 1.94 was obtained, which indicated that the vacuum thermal drawing technology provided an effective solution for the formability improvement of difficult-to-deformation materials with strictly protecting against oxidation.

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.