Influence of Internal Leakage in Hydraulic Capsules on Dynamic Behavior of Hydraulic Gap Control System

Abstract

In hot rolling mills the plastic deformation of the strip is realized at high force and plastic strain speed controlled by electro-hydraulic servo actuators. These hydraulic servo actuators - hydraulic capsules – are capable to adjust the rolling gap at great rolling force dynamically. The dynamic behaviour of the rolling mill’s AGC (automatic gap adjustment) system mainly depends on the correct operation of hydraulic actuators and servo valves. These equipments are great value, planned maintenance is essential for reliable correct operation. The maintenance includes the refurbish of damaged, worn surfaces inside the cylinder and replacement of worn out seals. In the study a laboratory hydraulic positioning system was used to examine the effect of hydraulic actuator internal leakage to dynamic behaviors of the positioning system. Because the laboratory test system is similar to the hydraulic gap adjustment system therefore the laboratory test results can be extended to the rolling mill’s Hydraulic Gap Control system.