Research On Rolling Process,Microstructure And Properties Of Large Profiled Ring

The radial-axial hot rolling process is superior in ring processing.The wall thickness could be reduced,the inner and outer diameters could be enlarged and the profiled section of billets could be shaped by ring rolling process.It is the main processing method used in the production of rings.With the rapid development of industry,the scope of application of profiled rings is expanding,and the requirement of dimension accuracy and quality of profiled rings in industrial production is gradually improving.Compared with common processing methods,ring rolling has more complex roll movement processes.The movement of each roller influences each other and acts on the billet synthetically.The ring was unable to bite into the pass,forge or loss instability if the rolls' moments used unreasonable rolling strategy.Based on the rigid-plastic finite element forming theory and the simulation software called Simufact Forming 15,the forging conditions of the profiled ring were deduced,and different billet schemes were designed according to the metal flow characteristics and the principle of volume invariance.According to different billet schemes,the rolling motion strategies of the profiled ring were analyzed,and the forming results were compared.Simufact Forming 15 was used to simulate the forming process of the profiled ring,and the appropriate forming process was obtained.The equivalent plastic strain,rolling force and friction change in the simulation results were compared and analyzed.Combined with the actual production of the factory,the reliability of the simulation schemes is verified.It is the best way to save the manpower and material resources consumed by the actual production,as well as improve the efficiency and the rate of good products.Reasonable material composition is the basis for obtaining high-quality ring properties,and the influence of heat treatment on the mechanical properties of rings is also crucial.Because the complex and harsh conditions of service put forward higher requirements for ring's performance,based on metallographic principle,this paper analyzed the effects of alloy elements on 42 CrMo material performance,and optimized the composition and designed the corresponding heat treatment process.By testing and comparing the mechanical properties of the optimized forgings and analyzing the crystal structure,it is proved that the mechanical properties of the profiled ring forgings have been improved,and the reasons for the improvement of the properties have been explored from the micro-crystal level.Combining with the actual production,it was found that the surplus material setting of ring forgings mainly depends on experience,which often causes unnecessary material losses.In this paper,the relationship between billet allowance and machining allowance of profiled ring was deduced by analogy.It has certain guiding significance for setting billet allowance in actual production and controlling processing accuracy of products.Based on the finite element theory,this paper studies the internal-profiled ring rolling method,combines the finite element software to design the schemes,optimizes the billet material and designs the heat treatment scheme.The mechanical properties of profiled rings are tested and the microstructures are analyzed.The relationship between the billet allowance and the machining allowance is explored.At the moment when the researches on the profiled ring are scarce,this paper has reference and guiding significance for the actual production of the profiled rings.