Research On The Key Technologies Of Radial Loading Gradually Rotary Extrusion Forming Of Components With Inner Ring High Ribs

The components with inner ring high ribs(CIRHRs)are key components required for lightweight major equipment in the fields of aviation,aerospace,and shipping.In order to achieve the best weight reduction effect,this type of component puts forward high requirements for the mechanical properties of the material body and the load-bearing capacity of key parts.The traditional manufacturing method of extruding thick-walled cylinders and then machining them to produce the required inner ring high ribs has problems such as low material utilization,small deformation,and incomplete metal flow lines,which cannot meet the requirements of significant equipment for high-strength and high load-bearing capacity of key components.However,traditional upsetting extrusion and spinning processes have problems,such as the inability to de-mold and form large-sized inner ribs.In response to the above issues,this article proposes a radial loading gradually rotary extrusion(RLGRE)forming method for CIRHRs.This article combines plastic forming theory analysis,calculation,finite element simulation,and physical experiments with interconnected macroscopic testing and microscopic analysis.The variation of forming load with the shape of the punch was studied and formulas for calculating axial and radial loads was established;the distribution laws of stress and strain during the forming process was analyzed,the deformation behavior and metal radial flow mechanism during the rib forming process was clarified;the influence of process parameters on the micro structure and mechanical properties of cylindrical blanks after rotational backward extrusion forming was study,and methods for regulating the microstructure and mechanical properties of cylindrical parts was proposed;the influence of top dies structure parameters and process parameters on the filling effect of inner ring high rib was studied,and optimization methods for punch structure parameters and process parameters was proposed;physical experiments on the formation of CIRHR were conducted,the mechanism of metal flow line formation was analyzed,and the mechanism of improving axial bearing capacity was elucidated.The theoretical calculation formulas for the punch’s radial load and the inclined wedge’s axial load in the radial loading progressive rotary extrusion forming method were derived using the principal stress method.The variation law of the radial load of the punch during the loading process and the maximum load variation law with the height of the punch work strip were obtained through finite element simulation technology.As the height of the working strip of the punch increases,the radial load gradually increases,and the increase amplitude gradually increases.Analyzed the stress and strain distribution and evolution law of the billet during singlepass radial loading and multi-pass radial loading,summarized the metal deformation behavior and radial flow mechanism.The radial tensile and axial compressive strain in the deformation area are the keys to forming inner ring rib.Increasing the compressive stress in the deformation area of the inner ring rib can promote the radial flow of metal at the inner ring rib,which is conducive to the filling and fullness of the inner ring rib.In order to ensure that the overall mechanical properties of the CIRHR meet the requirements,the rotary backward extrusion forming process was used to prepare cylindrical blanks.By combining finite element analysis with physical experiments,the influence of velocity ratio(the ratio of rotational linear velocity to axial extrusion velocity)on the micro structure distribution and mechanical properties of the cylinder was obtained.As the velocity ratio increases,the radial uniformity of the microstructure of the cylinder is improved,the mechanical properties of materials near the outer surface are improved,the difference in mechanical properties between the inner and outer surfaces is reduced,and the anisotropy is also significantly reduced.By using finite element simulation technology,the influence of top die structural parameters on the metal flow and internal rib filling effect of RLGRE forming process was studied.When the thickness h of the inner rib is constant,the filling fullness of the inner rib first increases and then decreases with the increase of the inclination angle a and height m of the working strip;as the transition arc radius r of the work zone increases,the filling fullness of the inner rib gradually increases.When the thickness h of the inner rib changes,the filling behavior of the inner rib can be divided into three types based on the relationship between the thickness h of the inner rib and the height m of the top die:insufficient filling,full filling,and excessive filling.At this point,the value of the height m of the working strip of the top die is closely related to the thickness h of the inner rib.The influence of the process parameters of RLGRE on the filling effect of inner ring rib was studied.The increase in pass feed rate Δb and pass rotation angle Δβ has an inhibitory effect on the filling effect of the inner rib,that is,as the pass feed rate Δb and pass rotation angle Δβ increase,the filling fullness of the inner reinforcement gradually decreases.The optimal combination of process parameters is:Δb=15mm,Δβ=45°,radial loading sequence:0→45°→ 135°→ 90°.A kind of CIRHR was trial-produced,which have good forming quality,full filled inner ring rib,and no macroscopic defects.The directional and reasonable distribution of metal flow lines has been achieved,and the load-bearing capacity of key components has been increased by 148%.The reliability of the forming process and dies design criteria has been verified,and the material utilization rate has been improved.The mechanism of improving the load-bearing capacity of the component was revealed,which is the combined effect of fine grain strengthening of the matrix and reasonable distribution of metal flow lines.The fine grain strengthening of the matrix contributes 45%to the improvement of bearing capacity,and the reasonable distribution of metal flow lines contributes 55%.