Simulation Analysis Of Double Flanging Flaring Forming For 5A02 Small Diameter Aluminum Alloy Tube

The 5A02 thin-walled aluminum alloy tube is one of the important parts in the aviation pipeline system,the sealing of pipeline system is directly affected by flanging forming quality of the tube end.Double flanging flaring forming is one of the most efficient ways to manufacture this kind of tube.The double flanging flaring forming process of the 5A02 thin-walled aluminum alloy tube is a complex uneven plastic deformation process that requires multi-pass,multi-field,multi-factor coupling.Therefore,in the forming process,the tube was prone to uneven plastic deformation in the forming area.To predict and control the wall thickness uneven plastic deformation of the 5A02 aluminum alloy tube end in the multi-pass double flanging flaring forming process,the FE analysis combined with theoretical and experimental methods for the process was used.The main research contents and results are as follows:(1)With the key technologies of FE modeling for the forming process solved based on ABAQUS/Explicit,such as geometric modeling,Load setting and meshing,a FE modeling of thin-walled aluminum alloy tube for double flanging flaring forming was established,and the reliability of the model was verified through the experiment.(2)Based on the established simulation model,the distribution laws during the double flanging flaring forming process such as equivalent stress and strain,stress and strain in the circumferential,tangential,thickness directions of tube in the deformation zone,were analyzed.The result shows that: When the first pass of forming is completed,the area with larger equivalent stress is mainly distributed on the outer surface of the tube forming area;the inner surface of the straight wall section of the forming zone is subjected to tensile stress in the tangential direction,while the outer and near outer surfaces are subjected to compressive stress;in the circumferential direction,the compressive stress on the top of the tube forming area is the largest,and the tensile stress on the outer wall of the cone section is the largest.while in the second and third pass,the larger equivalent stress area is distributed in the bending part of the forming zone.However,when the first pass is completed,the largest equivalent strain occur in the transition region between the straight and conical sections of the forming area;in the tangential direction,the compressive strain of the material in the transition area between the straight wall section and the conical section is the largest;in the thickness direction,the straight wall section of the tube forming area is affected by compressive strain;in the circumferential direction,the straight wall section is affected by tensile strain.in the second pass,the largest equivalent strain exist in the bending part of the forming region;in the tangential direction,the surface in the hemming area is subjected to tensile strain;in the thickness direction,the compressive strain is the largest at the surface fillet in the hemming area.the maximum equivalent strain of the third pass exist in the inner layer of the tube area in the forming zone.Meanwhile,with the progress of multi-pass forming,the equivalent strain from the first pass to the third pass shows a cumulative increasing trend;(3)The representation method of the uneven deforming degree of the tube end was proposed in the process,and based on the established effective finite element model,the effect of loading speed of the punch,the friction coefficient between the punch and the tube,the radius of the punch in the second pass,the friction coefficient between the die and the tube on uneven deforming degree of tube wall thickness during the double flanging forming process of aluminum alloy tube were studied in forming area.1)The results show that with the loading speed of the punch increasing,the uneven deforming degree of the tube end wall thickness increases firstly,and then decreases in the first pass of forming,while in the second pass,the uneven deforming degree of the tube is basically unchanged,and the uneven deforming degree of the tube end in the third pass decreases firstly and then increase.2)As the friction coefficient between punch and tube increases,the wall thickness uneven deforming degree of the tube end first decreases and then increases,the uneven deforming degree of the tube is basically unchanged in the second pass,while in the third pass,the uneven deforming degree of the tube tend to increase.3)With the increases of friction coefficient between the die and the tube,the wall thickness uneven deforming degree of the tube end first decreases and then increases,but the uneven deforming degree of the tube is basically unchanged in the second and third pass.4)With the increase of the radius of the punch in the second pass,the wall thickness uneven deforming degree of the tube end in the second pass tends to decrease.