Necking defects have long troubled the application of cross-wedge rolling technology in aluminium alloy shaft parts.To accurately predict necking defects,new judgement conditions are established based on the thermal p...Necking defects have long troubled the application of cross-wedge rolling technology in aluminium alloy shaft parts.To accurately predict necking defects,new judgement conditions are established based on the thermal performance of 6082 aluminium alloy.The limit-sectional shrinkage without necking defects is achieved by combining theoretical calculation and finite-element model analysis,which couples heat transfer and deformation.In this paper,a 6082 aluminium alloy extruded rod with a 40 mm diameter rolled at a preheated temperature of 500℃and a rolling angular velocity of 1 rad/s is taken as an example.The simulation and experimental results show that necking defects do not occur on the rolled pieces if the sectional shrinkage is below the limit-sectional shrinkage but will occur when the sectional shrinkage is above it.The results prove that the prediction model of necking defects in cross-wedge rolling of 6082 aluminum alloy is feasible,and this research provides a theoretical basis for the qualified aluminum alloy shafts produced by the cross-wedge rolling.展开更多
To realize cross-wedge rolling of shaft parts without a stub bar in a short process,an axial closed-open-type cross-wedge rolling technique was proposed.Based on the strain characteristics in the rolling,evaluation in...To realize cross-wedge rolling of shaft parts without a stub bar in a short process,an axial closed-open-type cross-wedge rolling technique was proposed.Based on the strain characteristics in the rolling,evaluation indices of deformation uniformity were provided,and the DEFORM-3D software was adopted to conduct numerical simulations of the rolling process.The metal flow and strain distribution in all stages of the rolling process were analyzed.It is shown that the strain value of the rolled piece close to the end is relatively high while the overall strain distribution is uniform in the rolling process.When the percentage reduction in area is smaller,the fluctuation range of the equivalent strain will be lower and the overall uniformity of the rolled piece will be better.A variable angle wedge was implemented to make metal flow inward and eliminate concavity.Finally,rolling experiment was performed,which indicate that the shape of the rolled piece obtained is consistent with the simulation results.Concavity value in the rolling is decreased by 92%as compared to conventional open rolling.The research results lay a theoretical basis for realizing closed-open-type cross-wedge rolling without a stub bar.展开更多
During the process of cross wedge rolling of aluminum alloy hollow shaft, the evolution of its microstructure has an important influence on the mechanical properties of the rolled piece. In order to obtain the microst...During the process of cross wedge rolling of aluminum alloy hollow shaft, the evolution of its microstructure has an important influence on the mechanical properties of the rolled piece. In order to obtain the microstructure evolution law of aluminum alloy hollow shaft in cross wedge rolling without mandrel, a finite element model is constructed through the finite element software Deform-3D. The influences of rolling temperature, sectional shrinkage,spreading angle and forming angle on the average grain size of rolled piece are studied by numerical simulation of microstructure evolution. The cellular automata method reveals the inherent relationship between the process parameters and the evolution of the microstructure, and provides a reference for optimizing the rolling process parameters of aluminum alloy hollow shafts and improving the forming quality. The results show that the average grain size of the rolled piece increases with the increase of the rolling temperature, decreases with the increase of the sectional shrinkage,and decreases first and then increases with the increase of the spreading angle, and changes little with the increase of the forming angle.展开更多
The problem of end-face cavity formation in parts produced by cross-wedge rolling was studied in order to reduce material consumption.The cavity depth was measured by the displacemern method.Twenty-one different cases...The problem of end-face cavity formation in parts produced by cross-wedge rolling was studied in order to reduce material consumption.The cavity depth was measured by the displacemern method.Twenty-one different cases of rolling were analysed by finile element method to determine the effects of process parameters such as the wedge tool angle,the temperature of material,the tool velocity and the reduction ratio on the depth of end-face cavities.Relationships between these parameters are examined in order to establish depe ndencies enabling quick and simple selection of a con cavity allowance in order to remove the cavities.The equations for calculating the con cavity allowance were verified in an experimental process for manufacturing ball pins with the use of flat tools.Rolling tests were performed using a billet with its length selected in compliance with the established dependencies.The experimental results demonstrate that the proposed solution is a viable method for end-face cavity removal.展开更多
This study presents a novel method using a disk-like sample to assess the workability of metal during the cross wedge rolling(CWR)process.Using this method,we can quantitatively evaluate the moment destruction which o...This study presents a novel method using a disk-like sample to assess the workability of metal during the cross wedge rolling(CWR)process.Using this method,we can quantitatively evaluate the moment destruction which occurs at the center of the sample during CWR.In this study,45 steel was selected to demonstrate the proposed method.Firstly,we designed a model for the tools and sample,conducted finite element simulations to analyze the distribution regulations of metal flow,stress,and strain,and evaluated the relationship between the damage and moving distance of the tool during the forming process.Then,we obtained the optimal deformation temperature range,rolling speed,and geometry parameters for the tool.Finally,experiments were conducted from 20℃ to 1200℃ to verify the accuracy of the developed model.It was demonstrated that the model was significantly accurate in accessing the workability of 45 steel in the CWR process.The proposed method could be generalized to investigate the CWR process for other materials,such as aluminum alloys,superalloys,titanium alloys,etc.展开更多
To further improve the comprehensive properties of 42CrMo/Q235 laminated shafts produced by cross wedge rolling.theheat treatment of the shafts was studied.Tensile and bending tests were carried out to compare the cha...To further improve the comprehensive properties of 42CrMo/Q235 laminated shafts produced by cross wedge rolling.theheat treatment of the shafts was studied.Tensile and bending tests were carried out to compare the changes in mechanicalproperties before and after heat treatment.The results showed that the interfacial bonding strength increased most aftertempering at 350℃for 45 min.The microstructure of the interface was observed using a digital microscope.The resultsshowed that the dispersed oxides on the interface were basically eliminated by using the scheme of tempering at 350 cand holding for 45 min.The reasons for the change in mechanical properties were explained from the point of theinterfacial microstructure.Scanning electron microscopy was used to analyze the micro-morphology of the tensile fracture.lt was observed that after tempering at 350℃and holding for 45 min,the dimple holes became larger and deeper,and thestructure of fracture became more uniform and stable.From the point of the tensile fracture morphology.the reasons for thechange in mcchanical propcrties wcrc explained as well.展开更多
基金Project(51975301)supported by the National Natural Science Foundation of ChinaProject(LZ17E050001)supported by the National Natural Science Foundation of Zhejiang Province of China。
文摘Necking defects have long troubled the application of cross-wedge rolling technology in aluminium alloy shaft parts.To accurately predict necking defects,new judgement conditions are established based on the thermal performance of 6082 aluminium alloy.The limit-sectional shrinkage without necking defects is achieved by combining theoretical calculation and finite-element model analysis,which couples heat transfer and deformation.In this paper,a 6082 aluminium alloy extruded rod with a 40 mm diameter rolled at a preheated temperature of 500℃and a rolling angular velocity of 1 rad/s is taken as an example.The simulation and experimental results show that necking defects do not occur on the rolled pieces if the sectional shrinkage is below the limit-sectional shrinkage but will occur when the sectional shrinkage is above it.The results prove that the prediction model of necking defects in cross-wedge rolling of 6082 aluminum alloy is feasible,and this research provides a theoretical basis for the qualified aluminum alloy shafts produced by the cross-wedge rolling.
基金The authors gratefully acknowledge the support of K.C.Wong Education Foundation.Hong Kong,the National Natural Science Foundation of China(Grant Number 51975301)the Natural Science Foundation of Zhejiang(Grant Number LZI7EO5OOO1).
文摘To realize cross-wedge rolling of shaft parts without a stub bar in a short process,an axial closed-open-type cross-wedge rolling technique was proposed.Based on the strain characteristics in the rolling,evaluation indices of deformation uniformity were provided,and the DEFORM-3D software was adopted to conduct numerical simulations of the rolling process.The metal flow and strain distribution in all stages of the rolling process were analyzed.It is shown that the strain value of the rolled piece close to the end is relatively high while the overall strain distribution is uniform in the rolling process.When the percentage reduction in area is smaller,the fluctuation range of the equivalent strain will be lower and the overall uniformity of the rolled piece will be better.A variable angle wedge was implemented to make metal flow inward and eliminate concavity.Finally,rolling experiment was performed,which indicate that the shape of the rolled piece obtained is consistent with the simulation results.Concavity value in the rolling is decreased by 92%as compared to conventional open rolling.The research results lay a theoretical basis for realizing closed-open-type cross-wedge rolling without a stub bar.
基金Project(52075272) supported by the National Natural Science Foundation of ChinaProject(LY18E050006) supported by the Natural Science Foundation of Zhejiang Province,China+1 种基金Project(2017A610088) supported by the Natural Science Foundation of Ningbo City,ChinaProjects(2018B10004, 2019B10100) supported by the Ningbo Science and Technology Plan,China。
文摘During the process of cross wedge rolling of aluminum alloy hollow shaft, the evolution of its microstructure has an important influence on the mechanical properties of the rolled piece. In order to obtain the microstructure evolution law of aluminum alloy hollow shaft in cross wedge rolling without mandrel, a finite element model is constructed through the finite element software Deform-3D. The influences of rolling temperature, sectional shrinkage,spreading angle and forming angle on the average grain size of rolled piece are studied by numerical simulation of microstructure evolution. The cellular automata method reveals the inherent relationship between the process parameters and the evolution of the microstructure, and provides a reference for optimizing the rolling process parameters of aluminum alloy hollow shafts and improving the forming quality. The results show that the average grain size of the rolled piece increases with the increase of the rolling temperature, decreases with the increase of the sectional shrinkage,and decreases first and then increases with the increase of the spreading angle, and changes little with the increase of the forming angle.
文摘The problem of end-face cavity formation in parts produced by cross-wedge rolling was studied in order to reduce material consumption.The cavity depth was measured by the displacemern method.Twenty-one different cases of rolling were analysed by finile element method to determine the effects of process parameters such as the wedge tool angle,the temperature of material,the tool velocity and the reduction ratio on the depth of end-face cavities.Relationships between these parameters are examined in order to establish depe ndencies enabling quick and simple selection of a con cavity allowance in order to remove the cavities.The equations for calculating the con cavity allowance were verified in an experimental process for manufacturing ball pins with the use of flat tools.Rolling tests were performed using a billet with its length selected in compliance with the established dependencies.The experimental results demonstrate that the proposed solution is a viable method for end-face cavity removal.
基金This work was financially supported by the Sino-Belarus Inter-Governmental S&T Cooperation project(Grant No.CB0209)the National Key R&D Plan(Grant No.SQ2018YFE011170)the Technical Innovation Program of Liaoning Province(Grant No.2020JH6/10500018).
文摘This study presents a novel method using a disk-like sample to assess the workability of metal during the cross wedge rolling(CWR)process.Using this method,we can quantitatively evaluate the moment destruction which occurs at the center of the sample during CWR.In this study,45 steel was selected to demonstrate the proposed method.Firstly,we designed a model for the tools and sample,conducted finite element simulations to analyze the distribution regulations of metal flow,stress,and strain,and evaluated the relationship between the damage and moving distance of the tool during the forming process.Then,we obtained the optimal deformation temperature range,rolling speed,and geometry parameters for the tool.Finally,experiments were conducted from 20℃ to 1200℃ to verify the accuracy of the developed model.It was demonstrated that the model was significantly accurate in accessing the workability of 45 steel in the CWR process.The proposed method could be generalized to investigate the CWR process for other materials,such as aluminum alloys,superalloys,titanium alloys,etc.
文摘楔横轧由于其工艺特点容易在成形轴件端部出现凹心,极大影响着轧件的轴端质量,但是直接切除凹心,不仅降低了轧件的材料利用率,还影响轧件的性能,为了解决这一问题,通过SPSS软件进行统计分析,发现工艺参数成形角α、展宽角β和断面收缩率ψ对轧件凹心的产生有显著影响:在同一断面收缩率下,凹心深度随着成形角的增大呈先减小后增大的趋势;随着断面收缩率的增大,凹心深度也在递增.断面收缩率为70%,成形角为34°时,凹心深度最大;在同一条件下凹心深度随着展宽角的增大而减小,呈反比关系.借助MATLAB进行数据拟合并建立回归方程模型,最后对模型进行优化计算,当工艺参数轧细长度为45 mm,断面收缩率为30%,成形角为26°,展宽角为8.8°时,凹心深度达到最小,最小值为6.7051 mm.
基金supported by the Fundamental Research Funds for the Provincial Universities of Zhejiang(No.SJLZ2021002)the Natural Science Foundation of Zhejiang Province(Grant No.LY18EO50006)+2 种基金the Natural Science Foundation of Ningbo City(Grant No.2017A610088)the Ningbo Science and Technology Innovation 2025 Major Project(2018B10004,2019B10100)National Natural Science Foundation of China(Grant No.51405248)。
文摘To further improve the comprehensive properties of 42CrMo/Q235 laminated shafts produced by cross wedge rolling.theheat treatment of the shafts was studied.Tensile and bending tests were carried out to compare the changes in mechanicalproperties before and after heat treatment.The results showed that the interfacial bonding strength increased most aftertempering at 350℃for 45 min.The microstructure of the interface was observed using a digital microscope.The resultsshowed that the dispersed oxides on the interface were basically eliminated by using the scheme of tempering at 350 cand holding for 45 min.The reasons for the change in mechanical properties were explained from the point of theinterfacial microstructure.Scanning electron microscopy was used to analyze the micro-morphology of the tensile fracture.lt was observed that after tempering at 350℃and holding for 45 min,the dimple holes became larger and deeper,and thestructure of fracture became more uniform and stable.From the point of the tensile fracture morphology.the reasons for thechange in mcchanical propcrties wcrc explained as well.
