The Simulation Of Heavy Cylinder Forging At High Temperature

Heavy forgings are performing as the key parts of the huge set of equipments, not only because of its large size and high demanded quality, but also for its complicated manufacture and high cost. As a typical product of intensive technology among heavy forgings, the heavy cylinder of a nuclear reactor is large, heavy, high-quality demanded, of many metallurgical defects and long cycle and difficult to manufacture. The high temperature forging process simulation is researched on the heavy cylinder of a nuclear reactor by using advanced FEM simulation technology, which is of great significance to contribute to enrich and develop theories and technologies of forging process and to design the forging process of heavy cylinder reasonably and automatically as well as to maintain the quality. The main purpose of the work was to find out the factors affecting the quality of the heavy cylinder forging.Core axial hole machining is the main process of heavy cylinder forging upon which the quality of heavy cylinder forgings depends. Guided by the new forging theories and technologies, combining with theories of heat transform of plastic deformation, the rigid-viscoplastic FEM is applied to research of heavy cylinder forging in order to find out the different strain status under various height reduction and rotating angles of sustaining cylinder. The main deformation of the heavy cylinder forging is in radial direction with small deformation in axial. The amount of deformation depends on the height reduction and the precision of the heavy cylinder forging depends on the rotating angle of the sustaining cylinder. The conclusions draw from simulation results are the theoretical base for the determination of right forging process. The distribution of inner stress, temperature, and the deforming force distribution and the flow law of metals were made clear.Combined with research results of numerical simulation, developed theories and technologies of forging process are applied to reexamine and revalue the existing core axial hole machining process of heavy cylinder of nuclear reactor. The model indicating the relationship between the height reduction and the rotating angle of sustaining cylinder in the forging process was set up and the rules of the deformation process were given out. The simulation results indicate that the amount of deformation increases with the increasing of height reduction. The precision of forging up goes and drops with rotating angle of sustain cylinder. The rotating angle between 30°- 40°could get better precision and should not go over 50°. When the coefficient of the rotating angleμis between 0.3 - 0.4, the simulation results shows the forging is of good thickness and high precision and meets the demand of circle requirement. As precision was concerned, the concave anvil performs better than flat anvil. The ending forging temperature depends on the lowest temperature of the forging surface that contacting with the sustaining cylinder. When the forging process comes to an end of one stage and at the beginning of another one in multiple stages forging, the rotating angle of sustaining cylinder should be reduced in order to gain a precise forging.Applying comprehensively with theories of forging process and the technology of numerical simulation, the simulation results are enabled to be advanced and applicable to guide design and to serve enterprises, which are suitable for improving the processes of heavy cylinder forging of nuclear reactor.The research is significant to guide how to improve the forging process design of heavy cylinder forging and how to fulfill the mechanization of heavy cylinder forging manufacture.