| Retaining rings is one of the most complex, the most severe conditions components of the generators,its manufacturing process is a standard level of national large turbine manufacturing capacity mark. The strengthen process technology of retaining rings is a very important part of the manufacturing process. Limited the level of manufacturing process, the current capacity of more the 300 MW generating units used rentaining rings are still rely on imports. In order to change this situation, the new technologies of shrengthen rentaining rings is urgent need to be developed.Retaining rings need high mechanical properties, high yield strength and plasticity index, homogeneous mechanical properties and small residual stress. Since the material Mn18Cr18 N is unidrectional austenite structure, with no phase transition, so it can’t be improved the mechanical properties by the conventional heat treatment methods, which can only be achieved with high mechanical performance requirements by means of work harden. The main method to strengthen the retaining rings is rehydration bulging method, but influenced by numbers of technological parameters, improper control of these parameters will make the Retaining rings defect or even scrapped.In this paper, the incremental theory is used for the retaining rings reinforcement of new technology theroretical analysis, the analytic solution of retaining strengthening process bulging pressure is give out, the relationship of upsetting and bulging ratio between the strengthening and effect of strengthening is deduced. The retaining rings strengthen blank size calculation formula is also deduced after the strenghen parameters determined. Loading path of strengthen process is obtained by using the bulging pressure analytic solution, and the use of finite element software DEFORM enhanced process simulation, finite element software analysis different loading conditions simulated path of retaining rings strenghen results, by comparing the result of obtained and find out the optimal load path. In this analysis, the compensation angle of die under different loading condtions is analyzed, and the relationship between load ratio and die compensation angle is obtained, the seal conditions are verificated, the methods of choose the strengthen Tonnage are given. Reference ductile fracture criterion to analyze the effect of ductile fracture creterion to the retaining rings strenthening, which provides a scientific basis for the selection of the strengthening ratio. |
