Development of servo-type micro-hydromechanical deep-drawing apparatus and micro deep-drawing experiments of circular cups

A micro-hydromechanical deep-drawing (MHDD) apparatus for manufacturing a micro-complex-shape components and increasing of drawn cup accuracy has been developed in this study. This apparatus with simple tooling structure and forming process can achieve high dimensional accuracy using servo press mechanics with a double-action type, one-stroke forming process without transferring and positioning, force control, and fine flow rate control of the pressure medium. The developed MHDD apparatus can prevent wrinkling by applying an appropriate constant gap and Stably generate the counterpressure. Micro drawn cups of 0.8 mm diameter are successfully fabricated. Also, the effects of counterpressure on drawability and dimensional accuracy at the bottom of the cup are investigated for phosphor bronze, stainless-steel, and pure titanium foils with a thickness of 50 mu m. The appropriate counterpressure applied in MHDD can eliminate wrinkling and reduce the frictional drawing force. It is concluded that the forming limit and dimensional accuracy can be improved by MHDD.