Four-column hydraulic press is the top cylinder to do what is the use

Our four-post hydraulic press at work, the processed products need to have a part of the product from the top of the mold, this time you need to install the top cylinder. Because the cylinder is a more important component on the four-post hydraulic press, adding a cylinder cost is high. So how does the top cylinder of the four-column hydraulic press work?
Four-column hydraulic press out of the cylinder The first step is the work of the top of the workpiece, the specific implementation of the master cylinder when the return to stop the movement, press the eject button, the corresponding three electromagnets were power, of which two cartridge valve open, 2 hydraulic oil into the valve through the valve into the valve chamber, the upper chamber oil flow through the tank back to the tank, the workpiece top. The second step is the top of the cylinder back, first press the return button, electromagnet loss of power, the other several electromagnets, power, cartridge valve open, hydraulic oil into the top of the valve through the cavity, Through the valve back to the tank, the top out of the cylinder back. When these steps are completed, the next step is started and a loop system is formed to maintain the continuous movement of the four-post hydraulic press.