Study On Evaluation Of The Cylinder Reliability Of The Large Tonnage Crane Based On The Fuzzy Extension Model

With the development of cranes to large tonnage or super-large tonnage, thedesign theory, structure form, design and manufacturing concept were innovated aswell. The structure design and seal design of hydraulic cylinder were also developed;the varieties of hydraulic cylinder, cylinder rod diameter specifications, stroke,materials, and pressure were increased progressively; new material and newtechnology were constantly enriched; therefore the safety risk of hydraulic cylinderwas increasing. The hydraulic cylinder test platform can not meet the requirements ofthe development of hydraulic cylinder at present，then a lot of hydraulic cylinder cannot use conventional methods and means to complete the test, especially thesimulation test.Therefore, the test data can not represent the authenticity of the host’sfor hydraulic cylinder. It has a certain theoretical significance and important practicalvalue for the research on evaluation of the cylinder reliability of the large tonnagecrane in this paper.Based on the basic theory of design and manufacture of hydraulic cylinders, thereliability factor of the hydraulic cylinder, evaluation of the reliability and acomprehensive evaluation model were studied in this paper.Firstly, the the classification, application and development trend, workenvironment, typical structure and working principle of hydraulic cylinders wereintroduced in brief in this paper; On this basis, for the reliability features of hydrauliccylinder of large-tonnage crane, the design reliability, manufacturing reliability, theusing reliability of the hydraulic cylinder was analyzed in depth, then the critical linkand key factors affecting the reliability of hydraulic cylinder such as the design andcalculation, the seal selection of features, manufacturing process, the processingtechnology and its quality control, the common failure modes and troubleshootingmethods of hydraulic cylinder were elaborated.Secondly, combining the principles, the index system of the evaluation to thereliability of hydraulic cylinder of large-tonnage crane was built, which include thedesign reliability, manufacturing reliability and using reliability. Meanwhile, the fuzzyextension evaluation model for the reliability of the hydraulic cylinder oflarge-tonnage cranes was constructed, using AHP to determine the weight of eachevaluation index, and using fuzzy extension evaluation model to evaluatesynthetically. Finally, a case was analyzed. Combined with the actual situation about the design,manufacture, testing of large tonnage cranes and its amplitude hydraulic cylinderwhich was manufactured in an engineering machinery enterprise, the evaluationreliability of this hydraulic cylinder was evaluated synthetically using the indexes andthe fuzzy extension evaluation model in this paper; the results show that the model areeffective to evaluating synthetically the reliability of hydraulic cylinders oflarge-tonnage crane, then a new effective evaluation tool and method was provided toevaluating the reliability of hydraulic cylinder for user. Therefore, some strategies andsuggestions which include improving the design rationality, reforming themanufacturing processes, and normalizing the repair and maintenance to improve thereliability of large-tonnage crane hydraulic cylinder were proposed in the paper.