The Research On Forming And Springback Of Metal Sheet For Adjustable Plate Forming Device

Multi-point forming(MPF) is a flexible manufacturing technology for three dimensional surface part of metal sheet.MPF utilizes a series of adjustable discrete elements arranged regularly to form intricacy curve surface,and achieves 3 D sheet figuration.By computer controlling the displacement and speed of elements the equipment of MPF can be adjusted figuration rapidly.In the shipbuilding industry,each shell plate is different,and batch production is not used.Therefore,line heating is widely used.However,this method of shape forming has its weakness.The quality of shell plate is poor,and the productivity is very low and labor intensity greatly.If the application of CNC technology can be applied on the automate plate bending,it will not only greatly enhance the work efficiency of bending plate production,but also reduce labor intensity,and will improve the accuracy of bending plate,thereby reducing the workload of assembly and correction.In the process of sheet metal processing,the springback phenomenon exists inevitable.Because in the process of sheet metal bending,the plastic deformation zones and elastic deformation zones exist on its cross-sectional area,what's more, plastic deformation exists in the elastic deformation zone,so when load-off,the bend radius of the plate will increased,and the bending angle will be decreased.It is called springback.Springback of sheet metal forming has a direct impact on the quality and duration of the ship.Conceptually,spring back is just a question about load-off,and it could be calculated easily.But it is the final step in forming,any error in the shell bending phrase will be calculated to the rebound phase,what's more,the values of spring back are small;the calculated accuracy in the springback simulation must be precise. Although springback is just a nonlinear and small deformation problem,it is essentially a process of stress state shifting to the elastic unloading state.It is much more complicated than the deformation calculation of the elastic structural.So,the problem about springback has not been solved for a long time.It is the most different problem in the shell forming simulation.In this dissertation,ANSYS/LS-DYNA will be used to study the problem about forming and springback.The mathematical sheet forming model will be build to calculate the stress on the metal sheet.The flat metal sheet will be formed to a spherical plateThe thickness of the metal sheet and the radius curvature are the two main factors in the multi-point bending process.In this paper,the two main factors will be studied.The influence among the maximum springback value and the two main factors will be revealed.