Abstract
In a large-scale hydraulic system having high repeated actuation cycle, such as a large type forging press, pressure surges often grow with great shock due to the recombination of the oil column separation in the return line attached to the downstream side of the directional control valve. This leads to restriction of the actuation cycle of the hydraulic system.
In this report, the relations between pressure surges and actuation time to close the valve were studied analytically and experimentally. Two different types of valve operation, that is linear, and break line two-stage were examined using a model hydraulic system having a directional control valve of similar flow characteristic as that of the valve usually used in the large-scale hydraulic system.
It was confirmed that the valve closing time can be shortened without increasing the surge pressure by using the break line two-stage valve operation which has lower operating speed near the closing point. And it was concluded that this type of valve operation is an effective method to increase the total actuation cycle of the hydraulic system.
