Analytical testing and methods for increasing the durability of plunger hydraulic cylinders

The article deals with the important problem of increasing the operating life of roll-balance system plunger hydraulic cylinders and describes the solution to this problem. The durability of plunger hydraulic cylinders determines not only the overall reliability of a hydraulic system, but also the technical and economic efficiency of the whole wide-strip hot rolling mill. Hydraulic cylinder durability depends primarily on the wear resistance of sealing units. Therefore in order to provide an effective approach to increasing the hydraulic cylinder life we have developed an analytical method for determining wear resistance of sealing units (i.e. determining a class or category) and calculating their expected operating life. The method is based on the solution of the fundamental equation of energy and mechanical theory of stationary units wear-fatigue as well as the theoretical provisions describing the strain pattern, initial and limiting values pertaining to plunger cylinders sealing units operating conditions. We have performed a computer experiment to study the behavior of various sealing materials and plungers with different antifriction coatings. As the result of the experiment we have established a number of ways to improve wear resistance of sealing units and durability of hydraulic cylinders by utilizing more durable elastomers and application of double-layer metal-polymer coatings. The most reliable design options of sealing units have been pilot tested and put into operation