Development of Digital Pressure Observer in Hydraulic Cylinders for Vertical Balancing of Rolling Stand Spindles

A literature review showed that the causes of accidents frequently occuring at rolling mills are fatigue failures of spindle heads or necks of mill rollers. This confirms the relevance of developing the systems for monitoring the wear degree of the spindle joint components directly during the rolling process. This is relevant for thick plate rolling mills operating under shock load application. As a diagnostic feature, it is proposed to use pressure in hydraulic cylinders of spindle vertical balancing. It has been experimentally proved that the process of fatigue failure development increases such pressure; that is why it is an informative criterion in terms of defect growth. The observer structure is proposed; at the observer output the variable pressure component is restored, and an emergency signal is generated. The algorithm for virtual observer configuration is implemented in the Matlab Simulink package. The proposed algorithm has been implemented in pilot operation on a thick plate mill 5000. The authors give an example of a pre-emergency situation on-line monitoring. The timely emergency warning has been registered and confirmed which proves the technical and economic efficiency of the observer adoption.