Prediction Of Residual Stress And Deformation In Milling Of Hollow Thin-walled Aluminum Alloy Welded Parts

The hollow thin-walled aluminum alloy welded parts are an important part of the highspeed train body.After welding,a balanced residual stress field will be formed inside the hollow thin-walled aluminum alloy welded parts.When cutting it,the residual stress field will be broken and redistributed,resulting in machining deformation.Due to its complex structure,complex residual stress will be generated because of cutting force and heat in the process of milling.The release of milling residual stress after machining will also cause the re-deformation of the workpiece,which makes it difficult to select the process parameters and restricts the train body manufacturing technology.In this paper,the milling process of hollow thin-walled aluminum alloy welded parts is studied based on finite element method,and the influence of rotational speed,feed per tooth and milling method on residual stress and deformation is analyzed.The main research of this paper is as follows:(1)A dynamic three-dimensional milling finite element model of 6005 A hollow thinwalled aluminum alloy welded parts is established.Milling experiment is conducted to verify the accuracy of the finite element model by comparing the chip shape and the residual stress measured by XRD with the simulation results.(2)The finite element simulation of side milling process of hollow thin-wall aluminum alloy component is carried out and the distribution law of milling residual stress is analyzed.The influence of first and second cutting on residual stress field is studied.The effects of rotating speed,feed per tooth and milling mode on milling force,milling temperature and residual stress are studied by single factor experiment.The results show that the cutting force,heat and residual stress increase with the increase of rotational speed and feed per tooth,but there is a threshold.The residual stress of down milling is less than that of up milling.(3)Based on the thermo-elastic-plastic method,the welding finite element model of hollow thin-walled aluminum alloy welded parts is established by using the double ellipsoid heat source model.The welding temperature field and stress field are analyzed and compared with the experimental data to verify the accuracy of the model.The results show that welding residual stresses are mainly distributed near the weld,and the heat affected zone is within the location of oblique wall.(4)A three-dimensional milling finite element model of hollow thin-walled aluminum alloy welded parts coupled with welding residual stress is established.The milling residual stress and deformation distribution of hollow thin-walled aluminum alloy welded parts are analyzed.The influence of milling position,rotational speed,and feed per tooth on milling residual stress and deformation is studied by single factor experiment.The results show that the welding residual stress will increase the deformation after milling;high rotational speed can control the deformation better,while excessive feed per tooth will cause large deformation and residual stress.The results show that welding residual stress plays an important role in milling residual stress and deformation of hollow thin-walled aluminum alloy welded parts.The finite element model coupled with welding residual stress can predict the distribution and variation of residual stress and deformation of hollow thin-walled aluminum alloy welded parts.