Numerical Simulation And Experimental Research On Hot Spinning Of Light Alloy Typical Thin-wall Rotatory Workpieces

Spinning is a typical local loading and forming technology.It has the advantages of low energy consumption,long die life and high precision.It is an effective method for manufacturing thin-walled hollow rotary parts.It has been widely used in aerospace,ship,weapon and other manufacturing fields.With the development of weapons and equipment technology,lightweight weapons have attracted more and more attention.The application of magnesium alloy,titanium alloy,high strength aluminum alloy and other light alloys is increasing.Under the condition of the same strength,the use of light alloy thin-walled spinning parts can effectively reduce the weight of parts to meet the needs of lightweight structure.However,because the requirements of magnesium alloy spinning on the deformation temperature and deformation rate are extremely strict;Titanium alloy is a typical material which is difficult to form,hot spinning process prone to bring about wrinkles,cracks and other defects,when the degree of deformation is large,the forming of magnesium alloy and titanium alloy is very difficult;For aluminum alloy,although the aluminum alloy spinning technology is widely used,the research on the rotary spinning process of the wheel is not mature because the technology has not developed well.In this paper,magnesium alloy,titanium alloy,aluminum alloy typical light alloy are discussed as the research objects combined with the development of military projects.Through the numerical simulation and experimental study on the forming of the three most widely used spinning parts of magnesium and titanium alloy cylinder with large aspect ratio,magnesium alloy rotatory crank rod and aluminum alloy wheel,the regularity and characteristics of light alloy material spinning will be explored in the article.The main contents and conclusions are as follows:1.Analysis and application of hot working diagram of light alloyBased on the high temperature compression experiments of Mg-Al-Zn alloy,TC11 titanium alloy and 2024 aluminium alloy,the rheological properties of three kinds of light alloy materials were analyzed.Based on the dynamic material model,hot working diagrams of three alloys were established,at the same time,by observing some microstructures under different deformation conditions,the deformation parameters suitable for the three alloys were determined,the deformation temperature of Mg-Al-Zn alloy is 350±25?and the strain rate is 0.01 s^-1,the deformation temperature of TC11 alloy is 925±25?and the strain rate is 0.01s^-10.1s^-1,the deformation temperature of 2024 alloy is 300?⁴50?and the strain rate is 0.01s^-10.1s^-1.The results of the research on the hot working diagrams provide the reference for the selection of the light alloys spinning process parameters.2.Spinning process numerical simulation of magnesium alloy and titanium alloy cylindrical partsFEA was carried out for magnesium alloy and titanium alloy cylindrical parts with length to diameter ratio of about 6:1.The forming characteristics,influencing factors and major forming defects are expounded.Through commercial finite element software ABAQUS,the finite element model of positive spinning about cylindrical parts was established,which discussed the problem of material model,contact boundary condition and mesh division and designed the structure parameters such as spinning blank,rotating wheel structure and multi-spinning wheel offset.Using the conclusions of hot working diagram,the range of temperature and deformation rate was initially selected.The forming schemes of magnesium alloy cylinder and titanium alloy with the tubular piece were developed.The feasibility of the scheme was analyzed by numerical simulation.The effects of process parameters,such as feed rate,thinning rate and spinning temperature on the forming precision and spinning pressure were analyzed.3.Numerical simulation of spinning of magnesium alloy and aluminum alloy complex rotary piecesCurved generatrix rotatory pieces are typical complex rotary parts.In order to obtain better economic performance,the scheme of sheet one-pass hot spinning based on positive deviation was proposed.The structure and size of the roller,roller swivel angle,the trajectory and gap of the roller,diameter to thickness ratio,the feed rate and the spinning temperature were studied,and the range of process parameters were determined.The stress and strain fields of the curved generatrix rotatory pieces spinning process were analyzed by numerical simulation.Split spinning as a special spinning method can be used to shape a variety of light overall wheel with advantages such as high forming efficiency and good economic effect.The aluminum alloy wheel split spinning is different from domestic and foreign research with the support of the rotary wheels.Based on the ALE method,the numerical simulation of the split spinning of the aluminum alloy was carried out.The stress and strain distribution law of the split spinning was obtained;the flange height difference and the ovality were analyzed.Based on numerical simulation of the multi-pass and the final rotation of the aluminum alloy wheel,the stress distribution of each pass is obtained,and the process parameters such as roller radius and feed rate are optimized.4.Optimization design of complex rotary parts process parameters based on orthogonal experiment methodBased on the orthogonal experiment design method,the influence of process parameters on the forming results of two kinds of special parts?curved generatrix pieces and splitting pieces?were analyzed.The five important factors were elected to evaluate the terminal wall thickness and ellipticity of the curved generatrix pieces and the flange difference and flange ellipticity of the splitting pieces.The influence order of the factors on the evaluation indexes was obtained,and the process parameters were optimized.The results show that the optimal parameters of magnesium sheet one-pass hot spinning are:D₀/t₀=18,T=300?,f=1.0mm/r,?=35°,R₂=5mm;The optimum parameters of the split spinning of aluminum alloy wheel are:?=25o,f=0.667mm/r,T=300?,R_M=5mm,R=1mm.5.Experimental research on spinning of light alloy cylindrical partsAccording to the spinning equipment,mold and tooling of magnesium alloy and titanium alloy cylinder with large diameter-length ratio were designed.Based on the analysis of the hot working diagram,the deformation temperature range of 300±20?for magnesium alloy,and 900±25?for titanium alloy.The appropriate lubrication was determined according to the deformation temperature and material properties.The linear trajectory feed scheme was adopted for magnesium alloy roller,the same slashing trajectory feed scheme with three rollers was adopted for titanium alloy.The forming precision of the magnesium alloy and titanium alloy cylindrical parts are analyzed,and the microstructure and mechanical properties were tested.The test results show that workpieces have good organization and performance which meet the product specification requirements.The test results are in good agreement with the simulation results,which verifies the feasibility of the scheme.The defects in the test of magnesium alloy cylinder were analyzed and the preventive measures were put forward,at the same time,the effects of spinning temperature,spinning trajectory,thinning rate and the non-coincidence of mandrel and spinning axis on forming precision were analyzed.The corresponding solutions were also put forward.6.Experimental research on spinning of light alloy complex rotary piecesThe experiment of forming the magnesium alloy hood one-pass hot spinning on the basis of FEA was carried out,and got the hood sample.The effects of diameter to thickness ratio,feed rate and spinning temperature on the wall thickness and ovality of the workpiece were studied.The experimental scheme further proved that the forming scheme was feasible.And then the causes of the defects such as peeling,reverse squeezing,uplift and ripple,crack and instability were analyzed.Based on the optimization of the parameters after the orthogonal test and the finite element simulation,the experimental research of 25osplit spinning and ordinary spinning was carried out.According to the test results,the program are obtained,which is 45osplit spinning—ordinary spinning—power spinning,and finally a qualified aluminum alloy wheel hub was formed.