Design of a special machine for viscous pressure forming

Viscous pressure forming (VPF) is a new advanced process for sheet forming. According to its characteristics a special hydraulic machine with novel structure, convenient operation and high controlling accuracy is designed in this paper. The hydraulic system of the machine is under control of a programmable controller, which enables the accurate settings of running time and location of the executive parts; and three proportional electro-hydraulic relief valves are used for the control of counter pressure at the ports of viscous medium, with the aid of a computer the curve of the counter pressure can be accurate set making the control of pressure in the female die cavity possible.