Identification based leakage detection of hydraulic capsules

In servo systems the hydraulic actuators are widely used when fast and accurate control is essential in addition to high force or torque. For this reason servo hydraulic system is commonly used in the modern strip rolling mills to adjust the gap between the work rolls. Automatic gauge control based on Hydraulic Gap Controller is commonly used in modern strip rolling mills to adjust the gap between work rolls. The dynamic control of rolling gap and force is achieved by using electro-hydraulic servo actuators - so-called hydraulic capsules - which can adjust the rolling gap dynamically for high rolling force. The basic aim of the paper is to monitor the parameter fluctuation of the Hydraulic Gap Control system in a Hot Rolling Mill and detect the alteration of internal leakage resistance at Capsule´s piston seal.