Simulation And Study On The Permeability Of Deformation And The Gradient Of Thickness In Rolling Plate

With the rapid development of such fields as the national marine platform,transportation,machinery manufacturing,there is an increasing demand for heavy plate as well as its property.However,there are some problems including the deficiencies in compression ratio,the differences in permeability of deformation and the unevenness in deformation in the process of conventional hot rolling.The technology of traditional medium plate rolling is restricted by motor current and the biting condition so that the press rate sometimes can not meet the requirements of productive process.Therefore,we can not get the steel plate whose core owns a good structure property.To improve the direction of plate's thickness and the permeability its deformation,the technology of thickness gradient rolling tries to continually change the press quantity and increase the press ratio in the process of rolling.Based on a domestic 3000mm plate rolling production line,this thesis adopts a method combining theoretical analysis,numerical modeling and experiment and makes use of the large finite element software,ANSYS/LS-DYNA,to do a modeling research on the laws of the thickness gradient rolling.The main contents of the paper are stated as follows:(1)On the basis of the document literature related to the thickness gradient rolling and the permeability of deformation at home and abroad,this paper discusses the deformation characteristics of thickness gradient rolling process after summarizing the development process of the thickness gradient rolling,which may establish a theoretical foundation for later researches on thickness gradient rolling.(2)Having studied the three-dimensional deformation theory of thickness gradient rolling,this paper bases on the conventional rolling and the characteristics of thickness gradient rolling itself to do a research on the thickness control model,the length and width prediction model,the rolling force and rolling moment model.(3)This paper briefly introduces the function and solving steps of ANSYS/LS-DYNA finite element software and the basic theory of dynamic elastic-plastic finite element,establishes a finite element analysis model of thickness gradient rolling and does a finite element analysis of the permeability of deformation and the laws of metal flow.(4)Based on the result of finite element modeling research,this paper deeply studies the change laws of metal flow,spread and extension,rolling force and temperature in medium plate's thickness gradient rolling process,especially the effect on the deformation permeability from different processes such as press ratio,diameter of roller,the thickness of the steel plate,rolling speed,coefficient of friction,initial temperature of the plate.(5)Contrastive experiments of thickness gradient rolling and conventional rolling of medium plate were finished in 3000mm hot rolling mill.The result of experiments showed that compared with the conventional rolling,thickness gradient rolling increases the deformation force of steal plate and improves the permeability deformation in the thickness direction to some extent and the mechanics performance.