Abstract
This paper deals with the hydraulic transient generated in the prefill line at the beginning of the compression cycle of a pull-down-type hydraulic machine press. Experiments were carried out on a small-sized simulation hydraulic circuit dynamically similar to a real machine of the 20-MN class. It was found that the four types of hydraulic transients, inclusive of the states which fell into poor operation, might be dependent on the system parameters. The following four topics of industrial interest were examined : (1) the limiting condition of occurrence of a column separation, (2) the cavitation duration following a column separation, (3) the surge pressure at the collapse of the first cavity, and (4) the cause of poor operation and the limiting condition of its occurrence. The values calculated from the proposed mathematical model agree with the measured values for these four topics with errors within about 10% over a wide range of operation.
