Theoretical And Experimental Analysis Of Four Roll Bending Process

Four roll bending machine is an indispensable part of forging machinery industry.Because of high machining accuracy,four roll bending machine has been gradually considered and applied to the container manufacturing enterprise,shipping industry and aerospace industry.But there many factors influencing the roll bending process lead to the complexity of the mechanism of four roll bending process,and which will limits its further development and application.Under the support of key research and development project of Jiangsu Province,this paper aims to study and analysis the Mechanism of four roll bending process in order to improve the forming quality of four roll bending products.Firstly based on pure bending theory and unloading spring-back theory,and combined the spring-back prediction numerical model,a four roll pre-bending and continuous bending numerical model was build.Secondly the dynamical simulation of four roll bending process was implemented using finite element analysis software Abaqus.According to the simulation result,the influence of friction between roll and plate,the stress and strain in the deformation zone during the four roll bending process,and influence law of factors state on the roll bending process were analyzed.The distribution of plastic strain on the upper surface of plate after multi-pass four roll bending were also investigated.By comparing the three roll symmetrical bending process and four roll bending process,the features and mechanisms of four roll bending process were analyzed.Last,the experimental verification of the typical plates for the four roll bending was conducted.The simulation and experiment results show that the forming quality of four roll bending products decreased with the increase of the displacement of side roll,processing speed,friction coefficient;the springback ratio decreased with the increase of plate thickness;The forming quality has been improving after the multi-pass roll bending;One of the main reasons for the inconsistency of forming radius of pre-bending section and continuous bending section is the friction between roll and plate;The forming accuracy after the four roll bending process is higher than that of three roll symmetrical roll bending process;After verification by experiment,the formative radius error is less than 8% for FEA model and 16% for the roll bending numerical model,both FEA model and roll bending numerical model has good behavior of industrial application.The research in this paper will supply theories basis and technical support for thedevelopment and application of four roll bending process.