A complete hydraulic system of hydraulic press is composed of five parts, namely, power components, executive components, control elements, auxiliary components (accessories) and hydraulic oil. Hydraulic system can be divided into two categories: hydraulic transmission system and hydraulic control system. The main function of hydraulic transmission system is to transfer power and movement. The hydraulic control system is to make the output of the hydraulic system meet the specific performance requirements (especially the dynamic performance). Generally speaking, the hydraulic system mainly refers to the hydraulic transmission system.
The function of the power component of the hydraulic system of the hydraulic press is to convert the mechanical energy of the prime mover into the pressure energy of the liquid. It refers to the oil pump in the hydraulic system, which provides power to the whole hydraulic system. The structure of hydraulic pump is generally gear pump, vane pump, plunger pump and screw pump.
The function of executive components (such as hydraulic cylinder and hydraulic motor) is to convert the pressure energy of liquid into mechanical energy and drive the load to perform linear reciprocating or rotary motion.
The hydraulic system control elements (i.e. various hydraulic valves) control and regulate the pressure, flow and direction of the liquid in the hydraulic system. According to the different control functions, the hydraulic valve can be divided into pressure control valve, flow control valve and direction control valve. The pressure control valve includes relief valve (safety valve), pressure reducing valve, sequence valve, pressure relay, etc.; the flow control valve includes throttle valve, adjustment valve, diversion and collecting valve; the directional control valve includes one-way valve, hydraulic control check valve, shuttle valve, directional valve, etc. According to the different control methods, the hydraulic valve can be divided into on-off control valve, fixed value control valve and proportional control valve.
Auxiliary components include oil tank, oil filter, cooler, heater, accumulator, oil pipe and pipe joint, sealing ring, quick change connector, high pressure ball valve, rubber hose assembly, pressure tap, pressure gauge, oil level gauge, oil temperature gauge, etc.
The hydraulic oil of hydraulic press is the working medium of transmitting energy in the hydraulic system. There are many kinds of mineral oil, emulsion and synthetic hydraulic oil.