3D Free Bending Springback Study Of Small Tubes

The bending members of tube are widely used in industrial field.Bending tubes can be found almost everywhere,from common household appliances in everyday life to aerospace products.Metal tubes not only meet the requirements of lightweight and high efficiency of industrial products,but also can be used as transport components of liquid and gaseous substances.It has the name of "industrial blood vessel".The 3D free bending process of tube is a new bending and forming process of tube.It can form complex bending tubes in three-dimensional space without changing the mold.It has the advantages of convenient processing and short production cycle.Springback is an unavoidable phenomenon in the forming process of metal materials,which is the main reason for the low quality of tube bending.Therefore,it is of great guiding significance to improve the bending and forming quality of tubes to study the mechanism of 3D free bending springback,analyze the influence of geometric and technological parameters on the 3D free bending springback of tubes,and predict the 3D free bending springback amount.This paper takes TP2 tube with an outer diameter of 12 mm and a wall thickness of 1mm as the research object.The main research contents are as follows:Based on the bending forming mechanism of the tube,the stress-strain analysis model in the 3D free bending and springback process of the tube was established,and the stress-strain calculation formula in the bending section of the tube was derived.By using ABAQUS software,the finite element model of the whole process of 3D free bending forming and springback of TP2 tube was established,and the key technical problems such as solving algorithm and mesh division in the finite element analysis process of 3D free bending tube were dealt with.Dynamic explicit algorithm is used to analyze the bending process and static implicit algorithm to analyze the springback process.The influence law of geometrical parameters and technological parameters on the 3D free bending springback of the tube was analyzed.The results show that,The springback Angle reaches the minimum value when the fillet radius of the guide mechanism is 1mm,the length of the bending deformation area is 23 mm,the clearance between the guide mechanism and the pipe is 0.4mm,the advancing speed is 120mm/s,the fillet radius of the bending die is 2mm,and the clearance of the tube die is 0.2mm,respectively,and the forming quality of the pipe is higher.Based on the neural network,the prediction model of 3D free bending rebound of tube is established.The orthogonal test of five factors and three levels was carried out on five parameters which have great influence on springback,such as fillet radius of bending die,length of bending deformation zone and clearance between bending die and tube.Sample data were provided for neural network training combined with finite element analysis to complete the training of neural network.By comparison,the prediction results of the model are in good agreement with the finite element analysis results,and the prediction model can accurately predict the springback Angle of the 3D free bending forming of the tube.Finally,the simulation and prediction results are verified by experiments.The research conclusion has guiding significance for reducing the elasticity of the tube in 3D free bending and improving the bending forming quality of the tube.