Improvement And Reliability Analysis Of The Hydraulic System For Z415Moulding Machine

Moulding machine is a indispensable equipment in foundry industry. With thedevelopment of industry, the demand of machinery parts will grows strongly. At the sametime, country is to implement energy conservation and the reduction of emissions, and themarket require high quality casting, so it is necessary to transform and improve theoutdated equipment, so as to adapt to the new market requirements. In this paper, a newhydraulic system is designed on the base of the old, to solve the problems that appeared inthe process of modeling work and meet the actual production. Reliability of the newhydraulic system is analysed, at the same time, the research of reliability analysis methodis also explored.Firstiy, to formulate low working efficiency and kinetic impact and failuresfrequently of the original hydraulic system of the molding machine, considering thequality requirements of sand mold the requirements of system pressure, the program ofchoosing a large displacement electro-hydraulic proportional pump to being the pumpsource is proposed, at the same time, adding to a multi-stage regulator module. Thecontrol program of electro-hydraulic proportional valve is proposed for the anti-platenhydraulic cylinder which has a larger impact in working process. The program of adouble-pump being auxiliary pump source is proposed in order to improve the reliabilityof the hydraulic control valve such as electro-hydraulic proportional valve, pilot operatedcheck valve and electro-hydraulic valve. The double-pump provides control oil for themain pump and the hydraulic control valve. Also, the main components of the system arecalculated and the new hydraulic principle is disscussed.Secondly, to assess the the reliability of the new hydraulic system, T-S fault tree inwhich the top event is sand molding failure is established, and the reliability of the systemis analysed and assessed based on the T-S fault tree. The failure probability of superiorevents and the top event are quantitative calculated according to the failure possibility ofevent,and the possibility of superior events and the top event fault condition arequantitative calculated according to the fault condition of basic events. The failure reason and links are analysised based on the results.Thirdly, to formulate the uncertainties of failure probability of basic events and fuzzypossibility of superior events, D-S theory is applied to integrate the experience and judgeof different experts and the interval failure probability of the interval fuzzy possibility ofsuperior events can be obtained. The T-S fault tree interval analysis method is proposedbased on the combination of interval analysis method and T-S fault tree analysis method.The T-S fault tree of sand molding failure is analysed based on T-S fault tree intervalanalysis method and the result shows the methed is feaasible.Finally, to formulate the problem that the failure rate interval of the superiors eventand the top event is obtained only when the values of the failure rate of the basic eventsare their extremum, which is difficult to occur in engineering practice, T-S fault treeinterval analysis method is proposed based on hyper-ellipsoid model, in which the failureprobability of basic events is constrained through hyper-ellipsoid model. The results showthat the method is feasible through example analysis.