Giant Forging Press Welded Connections Of Structural Stress Aberrations

Giant hydraulic press is a kind of infrastructure equipment in manufacturing industry, involving the application of the national economy in all fields, especially the field of plastic processing. This giant equipment is a characterization of national basic manufacturing capacity and important guarantee for national security. It has played an irreplaceable role in manufacturing the large-scale equipment of national major strategic projects and the modernization of national defence.The basic structure of 800MN giant forging hydraulic press is C-plate rack structure. C-plate, the key part to influence the carrying capacity, will influence the service life of the hydraulic equipment. So the checking and the optimization of the structure is the key to design the mainframe. On account of the lack of technology of entire forging recently and the high quality of welding, the manufacture of C-plate can be produced by the combination of welding and forging.Combined with the national key basic research program ("973" plan) "Forming equipment giant transmission power flow characteristics and high-precision manufacturing interface formation", the dissertation has made experimental study and theoretical analysis for the large welded joint structure of the 800MN giant forging presses. Based on the MARC simulation platform, the distortion rule and the control factors of stress of the welded connection composite structure have been studied. This thesis includes the following main aspects:The paper not only built the model of welded joints and made certain choice, partition principle of element mesh in modeling of welded joints, but also got the common principle for building welded joint structure model and provided theoretical evidences for the research of finite element modeling and analysis of welded joint structure.Through the tensile testing, constitutive and mechanical properties of the welded joints district of the material have been obtained for the FEA. The finite element model has been proved to be correct by comprising the results of experiments and FEA.Under tension, bending, torsion, shear loads and a variety of load combinations, the stress concentration factors of the welded joints have been calculated. The influence of welded joints thickness and load size on the stress concentration has been analyzed. the law of impact from load form,load size and geometry on stress distortion of welded joints has been obtained.Based on the Globe-Local algorithm of MARC software, combining with the stress distribution characteristics of the C-plate rack structure mainframe of the 800MN giant forging hydraulic press, we have proposed the general guidelines of the C-plate weld layout by building the finite element modeling of C plate with welded joints and studing the impact on structural performance made by the position of welding line.