Research On Material Flow And Surface Defect Control Technology In Rolling Forming Of Profile Ring

Ring rolling is a kind of local and continuous plastic forming process,which uses ring rolling equipment to reduce the wall thickness and expand the diameter of ring billet,and the desired profile ring is finally obtained.At present,there are many researches on the rolling of rings with simple rectangular cross-section,but for rings with profile cross-section,a large number of uncertainties are caused by complex nonlinear deformation,and the actual production quality is still difficult to meet the requirements,so further research on rings with profile cross-section is needed.The research object of this paper is a hard to deform alloy(TC4)case ring.The rolling process and defect control of the profile ring are mainly analyzed.Based on the influence of material flow behavior on rolling quality,the influence of rolling parameters and roll shape on material flow was discussed,and the causes of typical surface defects are analyzed.In order to reduce the occurrence of ring surface defects,a split-type mandrel structure was proposed,which can reduce the difference of material flow velocity on the surface of profile ring rolling.The main conclusions are as follows:(1)Based on the finite element simulation,orthogonal analysis and range analysis,the rolling process parameters of TC4 profile case ring are optimized.It is found that the diameter d of driving roller and the feed speed v of mandrel have the greatest influence on the material flow of the ring surface;the rolling parameters have different influence on the material flow in different parts of the ring,the rotation rate n of driving roller and the feed speed v of mandrel have the greatest influence on the shape and size of the ring.(2)With the increase of feed speed v of mandrel and friction m of driving roll,the difference of material flow speed tends to decrease.The difference of material flow velocity on the surface of the ring increases with the increase of rotating speed n and diameter d of the driving roller.From the tracking point of view,the ring material in the middle of the axial has a relative lag phenomenon.The influence of cone angle and friction on the material flow on the end face of the ring is small.After the optimized rolling parameters are introduced,the material flow velocity difference is reduced and the deformation is more uniform,which is beneficial to reduce the streamline and crack defects on the ring surface.(3)The split-type mandrel structure can reduce the material flow velocity difference on the inner surface of the ring,and the velocity difference tends to decrease with the increase of the number of ring mandrel.Therefore,it is beneficial for the uniform flow of materials in the rolling process of rings and reducing the streamline and crack defects.(4)There are material flow velocity differences on the surface of different profile rings.The ring shape is different,so the influence of the speed difference on the ring rolling forming is different.(5)The shape,size,microstructure and properties of the TC4 casing ring obtained by actual rolling production are qualified,and there are no obvious defects on the ring surface,which proves that the designed process plan is reasonable.