Research On The Sidewall Thickening Limit And Instability Of 6063 Aluminum Alloy Tube And Cylinder Part

With the development of human society entering the fast lane,the world is also facing the increasingly severe pressure on energy and environmental protection.The lightweight design for manufacturing industry is imperative in various countries.Based on the strong demand of energy-saving and environmental protection,thin-walled parts is widely used in manufacturing various key parts,because it can fully meet the requirements for lightweight and toughening of products.And its upsetting-extrusion forming process is also getting more and more attention.However,when the sidewall of thin-walled parts was subjected to axial load,the phenomenon of instability and wrinkle was easy to occur,which was also the most difficult problem to solve in the forming process.In view of the phenomenon that the sidewall of tubular and cylindrial parts was prone to bulge outward and fold when it was pressed axially.The inward and outward thickening forming process of the tubular sidewall was presented in this paper.In this method,the inner(outer)surface was restricted by die,so that the sidewall was thickened outward(inward).The thickening process of A6063-O aluminum alloy tubular sidewall was simulated by Deform finite element numerical simulation(FEM)software.And result of FEM was verified by the thickening experiment.On this basis,the inward and outward progressive thickening forming process of cylindrial parts sidewall was proposed.the preliminary results was obtained by simulating the thickening process in this research.(1)The inward and outward thickening process of tubular sidewall were simulated by DEFORM-3D.The result showed that: the thickening stability of the sidewall was related to the thickening direction.When the sidewall was thickened outward,it was prone to fold and occur instability defects.The forming stability was poor;When sidewall was thickened inward,there was no instability and folding defects.And the forming stability was high.(2)By tracing the thickening process of sidewall,it could be seen that the forming stability was mainly affected by the tubular size,thickening direction and axial stress distribution.In addition,according to the law of volume invariance,the theoretical limit thickness of sidewall could be obtained.And the instability criterion of the thickening process for sidewall could be established.(3)Through the design of forming die,the inward and outward thickening forming process of sidewall were verified by experiment.The experimental results showed that the forming process,thickness and forming load were consistent with the numerical simulation results.(4)Based on the inward and outward thickening forming process of tubular sidewall,the inward and outward progressive thickening forming process of cylindrial parts sidewall was proposed.The thickening process was simulated by DEFORM-2D.It could be found that the fillet area folds,when the sidewall was gradually thickened outward,the material fluidity of sidewall area was poor,the filling rate was low and the thickening height of sidewall was low;In the inward progressive thickening process,the material fluidity was good.the filling rate was high.And the thickening height of sidewall was high;With the increase of punch force,the thickening effect of sidewall was better.The local thickening forming method effectively eliminateed the influence of slenderness ratio on the thickening process.The small fillet and unequal thickness cylindrical workpiece could be form in one step by this method.