Research On The Shape Change And Bending Moment Distribution Of Aluminum Flexible 3D Stretch Bending Parts

The flexible 3D stretch bending process is a combination of flexible manufacturing concept and 3D bending process.The flexible 3D stretch bending of profiles discretizes the traditional integral die into a series of independently adjusta ble roller dies,which makes it easy to adjust the shape,thus shortening the production cycle and reducing the production cost.However,due to the characteristics of flexible stretch bending forming die,there are contact zone and non-contact zone between profile and roller die,which will lead to the difference of shape change between contact zone and non-contact zone of profile,and directly affect the forming quality and accuracy of parts.At the same time,due to the different stress state of contact zone and non-contact zone,the distribution of bending moment in contact zone and non-contact zone is also different.In this paper,the finite element modeling of flexible 3D stretch bending of profile is carried out by using the finite element software ABAQUS,and the reasonable mesh generation,element selection,correct material model and boundary conditions are carried out.In this way,the flexible 3D stretch bending process is simulated and the accuracy of numerical analysis results is ensured.It is very important for the forming quality and precision to keep the section shape after stretch bending.In this paper,the section deformation of profile web after deformation is studied,and the difference of section deformation between profile and roller die in contact zone and non-contact zone is explored.The height and thickness deformation of web are taken as evaluation criteria.In addition,by changing the pre-stretching amount and bending angle of the profile,the influence of the pre-stretching amount and bending angle on the cross-section deformation of the profile in the contact zone and non-contact zone is explored.The distribution of bending moment during stretch bending has a great influence on the accuracy of bending.In this paper,the normal stress distribution law on the cross-section of the profile is analyzed.Besides,the axial normal stress distribution difference between the contact zone and the non-contact zone of the profile is explored,and the axial normal stress distribution diagram is obtained.Then,according to the normal stress distribution on the cross-section of the profile,the bending moment on the cross-section of the profile is calculated,and the bending moment distribution of the whole profile in the contact zone and non-contact zone is obtained.Finally,the difference of curvature variation caused by bending moment in contact zone and non-contact zone is obtained by measuring the shape of the profile.In the flexible 3D stretch bending process,it is found that the shape deviation of the non-contact zone between the near clamp and the far clamp is different.Therefore,on the premise of the same number of roller dies,the shape deviation of the non-contact zone of the profiles at different positions is explored by changing the spacing between the roller dies.In addition,the web height and web thickness of profiles in contact zone and non-contact zone are also studied under the condition of different spacing of roller die.