Research Of Feeding Movement On Multi-station Press Based On Dynamic Finite Element Analysis

In the production of automobile panel on multi-station presses,analysis and optimization of feeding movement can be used to avoid collisions between sheets and tools.Thus the stability and reliability of the handling mechanism are guaranteed,and the strokes per minute can be improved.Dynamic simulation is considered to be one of the most effective means to achieve this goal.However,existing interference analysis is only based on rigid kinematics simulation and static assembly simulation.Thus,it is significant to explore a new method considering the deformation of sheets with vibration.Investigation to the feeding movement on multi-station press shown that available interference simulation method which could consider the deformation of sheets with vibration is dynamic finite element.Theories and examples were discussed to conclude that the Ansys Workbench and Ls-dyna were feasible software.After study on feeding mode of multi-station press line,a new method of discretization and fitting was used to obtain the motion curve function,customized links were created to realize three-dimensional movements.Then the rigid kinematics simulation of entire handling movement has been finished with UG Motion.According to the result,the motion curve function was accurate,and no interference was found in this condition.To solve the difficulty in calculating the complete model of ejection mechanism on the first station by finite element method,equivalent rigid dynamic ejection model was established.Thus,a method for optimizing the model by simplifying the surface of die and punch has been found,and also a control pin device was created to reduce the vibration of sheet during ejection,in which way dynamic finite element simulation shown that the elastic deformation of the sheet could be reduced from-15~+30mm to-10~+7mm.At the same time,a set of suitable ejection parameters were obtained by comparison.The result proved that the vibration of sheet was in the safe range without any clamping interference.Simulation and analysis for the advance movement of all stations were carried out.It was found that the vibration of sheet in first station was the largest in all station,and the vibration of sheet in M3 mode was the smallest in all modes.Finally,the whole movement of ejection and handling was analyzed.Two kinds of handling methods,including shovel-type fixture and clamp-type fixture,have been compared,based on the production situation,it was considered that the shovel-type fixture was the best choice.According to the production experience,the simulation of the whole feeding movement was an innovative and valuable method to forecasting the problem of interference and reliability.Basing on Hypermesh,the pre-processing of feeding movement analysis were designed and developed,which made the pre-processing more standardized and easier.