Simulation And Experimental Research On Loading Paths Of Retaining Ring Hydraulic Bulging

The localization of large power equipment is an important guarantee related tonational economic sustainable development and national strategic security. Retaining ringis one of the most important key parts in power equipments.On the basis of NTAhydraulic bulging new technology of retaining ring, the loading path of600MW large ringhydraulic bulging under the55°die angle was mainly studied in this paper.Based on the plane finite element model, under the action of liquid pressure alone,the deformation characteristics of inside and outside layers during retaining ring hydraulicbulging was studied, and the relationship between liquid pressure and the size of the ringin plastic deformation stage was fitted. Based on the axisymmetric model, the influencelaw of outer contour with the change of liquid pressure and axial force was studied.Different models’ liquid pressure required when starting to produce plastic deformation, inboth inside and outside layers, is considered to be approximately the same. Liquidpressure plays a main role in the process of retaining ring hydraulic bulging. If the liquidpressure and axial force matched well, it can make the ring neither convex nor concave.By adoption of sectional matching method, the continuous bulging process wasdivided into n small processes. Under the precondition to meet the geometrical quality ofthe ring forming, the matching relation between axial force F and liquid pressure P in eachsmall process was respectively studied, and the loading path of the retaining ring hydraulicbulging was determined. Further research shows the matching relationship between theloading path of the axial force F and liquid pressure P can be simplified approximately tobilinear form, and the turning point of the liquid pressure slightly less than the criticalliquid pressure under the conditions of plastic deformation which occured in the outer ofthe retaining rings. For the convenience of practical production, the loading path wassimplified into a bilinear model, and it was determined that the bilinear inflection point ofthe liquid pressure is slightly less than critical liquid pressure under the conditions ofplastic deformation which occured in the outer of the retaining rings.20#steel for the1:8retaining ring hydraulic bulging experiment was used. Based on the above research methods, the double linear loading path of20#steel was obtained, theloading path for experiment was determined and the feasibility of double linear loadingpath was verified.