Study On Free-bending Forming Mechanics Principle And Forming Control Of Sheet Metal

Sheet bending is widely used in modern production,and free bending is one of the bending methods.It is widely used in small batch production because of its simple molds and convenience bending multiple angles.The free bending die size and bending process have a great influence on the bending process and forming quality of the sheet.The springback of the sheet after unloading is the biggest defect in the bending process.The influence factors of sheet forming and springback are analyzed through the study of the mechanics principle in the process of free bending of the sheet material.In this paper,the free bending of 304 stainless steel sheet,aluminum sheet and T2 copper sheet is studied.The bending model of the sheet is established by theoretical analysis.The correctness of the sheet bending model is verified by the experimental study.The BP neural network is used to establish the free bending model of sheet material,and the experimental data are trained and tested.It shows that the model can accurately predict the free bending process of the sheet material.The experimental sheet forming is modeled by Simulink,and the BP neural network model is introduced by S function.The target angle and forming angle are analyzed.The PID control algorithm is used to control the sheet metal forming,and the bending stroke of the sheet is calibrated according to the actual situation of the experimental sheet forming.The results show that the simulation model is accurate.The main contents of this paper are as follows:First,the mechanical principle of the free bending of the sheet is analyzed,the relationship between the bending force and displacement of the sheet is established,and the proper material model is used to fit the relationship between the bending force and displacement of the sheet material,and the relationship between the bending moment curvature and the stress strain of the sheet is obtained by theoretical analysis.Secondly,according to the relationship between bending moment and curvature,the bending process of sheet material is studied in stages,and the comparison between the bending radius of sheet material and the radius of the punch angle is mainly divided into the unwrapped punch and the covered punch stage to study the free bending process of the sheet material,to confirm the elastic-plastic properties at some point and to solve the elastic-plastic sheet material at a certain point.The relationship between the coordinates of the sexual intercourse and the bending force.The elastic effect at the junction point after unloading is analyzed,the bending angle after springback is solved,and compared with the experimental results.Then,the BP neural network prediction model of the free bending process of the sheet is established,and the input and output nodes of the suitable model are selected and the number of the nodes of the hidden layer is determined according to the empirical formula.The network model is trained by experimental data,and the accuracy of the model is verified.Therefore,the free bending process of sheet metal can be accurately analyzed through the model.Finally,the simulation model of the experimental platform is set up.Through the measurement of the parameters of the experimental equipment,the parameters of the simulation system are modified to ensure the integration of the simulation system and the actual platform.The BP neural network model is encapsulated and introduced into the simulation system by using the S function in Simulink,and the PID algorithm is introduced to control the simulation system,so that the bending angle and the target angle of the sheet can be reached to a certain precision.