Research On Accumulated Upsetting Extrusion Flange Of Thin-walled Cylinder

Flange parts are usually used as a connecting part between pipes and shafts.Due to their good sealing properties,they have been widely used in industrial production.So far,scholars at home and abroad have no good solution to the problem of forming large thick flanges.Most of them are produced by casting and welding.However,there are many flange parts manufactured by casting Defects,such as coarse grains and poor mechanical properties.For such parts produced by welding,the mechanical properties of the welds are seriously reduced.Therefore,for some flange parts used in harsh environments,the above methods are far from meeting our requirements.The cumulative upsetting method proposed in this paper is a new technology for forming flange parts.This process is mainly to control the thickness of the flange through the movable die,so as to avoid the instability caused by the high aspect ratio during the forming process,and can also obtain higher comprehensive mechanical properties.In this paper,the cumulative upsetting extrusion method is taken as the research object,the rule of folding in the forming process is studied,and its accuracy is verified through experiments.The DEFORM-2D/3D finite element simulation software is used to compare the forming load,stress,strain and metal flow law of the traditional radial extrusion and cumulative upsetting method,and the advantages of the cumulative upsetting method are obtained by comparison.After that,the forming process of the cumulative upsetting extrusion method is further analyzed to study the forming effect of the flange and its influencing factors.For its key forming step,flange forming,through finite element numerical analysis and comparative analysis,the maximum ratio of the mold cavity width w to the tube billet wall thickness t is summarized,that is,w/t=6.8.When the ratio w/t<6.8,a perfect flawless flange can be formed,and the thickness of the flange can be infinitely thickened;when the ratio w/t?6.8,the flange thickness cannot be increased without limit Thick,when the flange reaches a certain thickness,it will fold.And as the value of w/t increases,the earlier its folding occurs.When the w/t ratio is sufficiently large,defects will occur at the beginning of the second phase.Therefore,it is most critical to control the ratio of flange width w to tube wall thickness t.This solves the problem of forming thick flanges.In the case of flange forming when w/t?6.8,and compared the impact of extrusion temperature,extrusion speed,die fillet size and friction coefficient on flange forming.By analyzing the forming load,equivalent stress and equivalent strain of different extrusion temperature,extrusion speed,die fillet,friction coefficient,the best process parameters are determined: the extrusion temperature is 440?,and the extrusion speed is 1mm/s,the die fillet is 5mm,and the friction coefficient is 0.25.Finally,in order to verify the feasibility of the upsetting method of cumulative forming,a validated experimental scheme is designed in this paper,and the experimental results have achieved the expected results,which provides a reference for the machining and forming of large thick flanges.