Based on the design of the multi-row sprocket with a new tooth profile,a cold semi-precision forging process for manufacturing 5052 aluminum alloy multi-row sprocket was presented.Through simulating the forging proces...Based on the design of the multi-row sprocket with a new tooth profile,a cold semi-precision forging process for manufacturing 5052 aluminum alloy multi-row sprocket was presented.Through simulating the forging process of 5052 aluminum alloy sprocket billet with 3D rigid-viscoplastic FEM,both the distributions of flow velocity field in axial(U_Z),radial(U_R) and circumferential(U_θ) directions and the curves of velocity component in different deformation regions were respectively obtained.By comparison and analysis of the velocity varying curves,the velocity component relation conditions for filling the die cavity were clarified.It shows that when the die cavity is almost fully filled,the circumferential velocity U_θ increases sharply,implying that U_θplays a key role in fully filling the die cavity.展开更多
In order to obtain the desired final shape, the blade precision forging requires a reasonable preformed billet which can be obtained from a given final shape by using backward tracing scheme based on FEM. The key tech...In order to obtain the desired final shape, the blade precision forging requires a reasonable preformed billet which can be obtained from a given final shape by using backward tracing scheme based on FEM. The key technologies of backward tracing scheme based on 3D rigid-viscoplastic FEM were explored, and some valid algorithms or methods were proposed. A velocity field was generated by combining the direct iterative method with Newton-Raphson iterative method, and then the initial velocity field of backward tracing simulation was achieved by reversing the direction of the velocity field. A new method, namely the tracking-fitting-revising method, was proposed and can be used to determinate the criterion of separating a node from die in the backward tracing simulation. The ceasing criterion of the backward tracing simulation is that all the boundary nodes are detached from dies. Based on the above key technologies, the 3D backward tracing simulation system for the blade precision forging was developed, and its feasibility and reliability were verified by forward loading simulation.展开更多
The precision forging process is simulated by commercial software Deform 3D using a rigid visco-plastic model to predict the status of metal flow and the distribution of equivalent plastic strain,providing guidance fo...The precision forging process is simulated by commercial software Deform 3D using a rigid visco-plastic model to predict the status of metal flow and the distribution of equivalent plastic strain,providing guidance for making decision on the optimal choice of process parameters and mould structure.Trial forging was used to verify the effectiveness of FEM simulation results.展开更多
The present paper examines the deformation behavior of solid cylinders of an aluminium alloy metal matrix composite (MMC) undergoing axial compression in a Universal Testing Machine under dry condition. The composite ...The present paper examines the deformation behavior of solid cylinders of an aluminium alloy metal matrix composite (MMC) undergoing axial compression in a Universal Testing Machine under dry condition. The composite was pre- pared by the stir casting method from LM6 aluminium alloy using silicon carbide particles (SiC) as reinforcing agent. The effect of weight percentage of silicon carbide on microstructure, hardness and upsetting load is studied. The friction factor at die metal interface is evaluated by ring compression tests and its effect on non-uniform deformation is investi- gated. The experimental results are finally compared with those obtained by FEM simulation.展开更多
The hot forging of large-scale P/M TiAl alloy billet deformation was investigated based on a joint application of Deform-3D-based numerical simulation and physical simulation techniques.The temperature dependence on t...The hot forging of large-scale P/M TiAl alloy billet deformation was investigated based on a joint application of Deform-3D-based numerical simulation and physical simulation techniques.The temperature dependence on the thermal and mechanical properties of the billet was considered and the optimum hot working temperature of packed TiAl alloy was 1150-1200 °C.Based on the simulation,the material flow and thermo mechanical field variables,such as stress,strain,and temperature distribution were obtained and the relationships of load—displacement and load—time were figured out.To verify the validity of the simulation results,the experiments were also carried out in a forging plant,and a pancake with diameter of 150 mm was obtained exhibiting a regular shape.展开更多
A numerical analysis was performed to study the influence of process parameters on the microstructure evolution of IN718 alloy in rotary forging using the finite element method （FEM）. For this purpose, a constitutiv...A numerical analysis was performed to study the influence of process parameters on the microstructure evolution of IN718 alloy in rotary forging using the finite element method （FEM）. For this purpose, a constitutive equation considering the effects of strain hardening and dynamic softening of IN718 alloy was built. The constitutive equation and microstructure models were implemented into the finite element code to investigate the microstructure evolution during rotary forging subject to large deformations. The simulations were carried out in the ratio of initial height to diameter range 0.2-0.8, the angle of the rocker 3°-7° and the relative feed per revolution range 0.01-0.1 r^-1. The research results revealed the deformation mechanism and the correlation of process parameters with the grain size evolution of IN718 alloy during rotary forging. These provide evidence for the selection of rotary forging parameters.展开更多
In order to eliminate forging defects appearing in production,based on the rigid-viscoplastic FEM principle,the DEFORM3D software package was employed to simulate the forming process of TC4 alloy mounting part and to ...In order to eliminate forging defects appearing in production,based on the rigid-viscoplastic FEM principle,the DEFORM3D software package was employed to simulate the forming process of TC4 alloy mounting part and to optimize the process parameters.In this simulation,the temperature dependency of the thermal and mechanical properties of material was considered.Based on the simulation,the metal flow and thermomechanical field variables such as stress and damage are obtained.The simulation results show that the forging defects are caused by improper die dimension and the optimized die dimension was proposed.To verify the validity of simulation results,forging experiments were also carried out in a forging plant.The forging experiments show that the optimized die dimension can ensure the quality of forging part,and it can provide reference to improve and optimize die design process.展开更多
The 3D FEM numerical simulation on multi-action precision cold forging technology of universal joint cross and differential spider is done in this article using DEFORM Software, a commercial computer aided engineering...The 3D FEM numerical simulation on multi-action precision cold forging technology of universal joint cross and differential spider is done in this article using DEFORM Software, a commercial computer aided engineering software specializing in forming and heat treatment simulation technology, and suitable for cold, warm and hot forging process. The material flow properties, the dynamic variation of stress and strain in the process of deformation and the load-stroke curve have also been achieved. A good consistency is exhibited between simulation results and practical data. Based on the DEFORM simulation results, the optimized procedure has been found for forging a universal joint cross. What should be emphasized here is that a better understanding of practical forging characters and the environmental factors can greatly improve the simulation accuracy thus make the simulation results more reliable.展开更多
To investigate the effects of billet geometry on the cold precision forging process of a helical gear, six different billet geometries were designed utilizing the relief-hole principle. And the influences of the bille...To investigate the effects of billet geometry on the cold precision forging process of a helical gear, six different billet geometries were designed utilizing the relief-hole principle. And the influences of the billet geometry on the forming load and the deformation uniformity were analyzed by three-dimensional （3D） finite element method （FEM） under the commercial software DEFORM 3D. The billet geometry was optimized to meet lower forming load and better deformation uniformity requirement. Deformation mechanism was studied through the distribution of flow velocity field and effective strain field. The forging experiments of the helical gear were successfully performed using lead material as a model material under the same process conditions used in the FE simulations. The results show that the forming load decreases as the diameter of relief-hole do increases, but the effect of do on the deformation uniformity is very complicated. The forming load is lower and the deformation is more uniform when do is 10 mm.展开更多
The microstructure models were integrated into finite element（FE）code,and a three-dimensional（3D）FE analysis on the entire hot forging processes of 300 M steel large components was performed to predict the distrib...The microstructure models were integrated into finite element（FE）code,and a three-dimensional（3D）FE analysis on the entire hot forging processes of 300 M steel large components was performed to predict the distributions of effective strain,temperature field and austenite grain size.The simulated results show that the finest grains distribute in the maximum effective strain region because large strain induces the occurrence of dynamic recrystallization.However,coarse macro-grains appear in the minimum effective strain region.Then,300 M steel forging test was performed to validate the results of FE simulation,and microstructure observations and quantitative analysis were implemented.The average relative difference between the calculated and experimental austenite grain size is 7.56%,implying that the present microstructure models are reasonable and can be used to analyze the hot forging processes of 300 M steel.展开更多
Based on the experimental data from hot compression tests on Gleeble 1500 thermal simulator, the revised constitutive equations of spray-formed FGH95 superalloy considering the effect of strain on the material constan...Based on the experimental data from hot compression tests on Gleeble 1500 thermal simulator, the revised constitutive equations of spray-formed FGH95 superalloy considering the effect of strain on the material constants were established. The average absolute relative error （AARE） was employed to verify the validity of the constitutive equation, and the value of AARE is 3.85 %. Subsequently, the revised constitutive equations were successfully used to simulate and analyze the deformation behavior, stress distribution, forming loads and temperature distribution in both dies and billet during the isothermal forging process of turbine disk of large dimension （about 400 mm in diameter） by the means of finite element method （FEM）. Moreover, the optimum process parameters are 1,120 ℃ of forging temperature and 0.01 s^-1 of strain rate for the spray-formed FGH95 superalloy turbine disk.展开更多
Basing on the analysis of the traits of the roll forging process, a system-model of computer simulation has been established. Three-dimensional rigid-plastic FEM has been used for the simulation of the deformation pro...Basing on the analysis of the traits of the roll forging process, a system-model of computer simulation has been established. Three-dimensional rigid-plastic FEM has been used for the simulation of the deformation process in the oval and round pass rolling, including the entering, rolling, and separating stages. The analysis was conducted using the Deform-3D ver.5.0 code. The important information concerned with the deformation area characteristic, material flow, and velocity field has been presented. Otherwise, the location of the neutral plane in the deformation area was shown clearly.展开更多
The rotary forging process of a disc is simulated by 3-D finite element method.The motion of the rotary the is described as the combination of a revolution round the machine axis and a spin round the rotary die axis...The rotary forging process of a disc is simulated by 3-D finite element method.The motion of the rotary the is described as the combination of a revolution round the machine axis and a spin round the rotary die axis. Therefore, the workpiece can be loaded and unloaded partly and cyclically by the cone surface of the rotary the continuously, according with the practical rotary forging process. From the siumulation rasults, the causes of center-thinning during rotary forging of discs are that the locally loading of rotary die made the workpiece center get high radial and tangential tensile stresses, and then the shortening in axial direction and the elongating in tangential and radial direction occur continuous- ly.展开更多
The closed die forging(or fully-enclosed die forging) method was employed to form a rotor instead of the conventional machining method. A combined female die was designed so that the rotor could be released easily fro...The closed die forging(or fully-enclosed die forging) method was employed to form a rotor instead of the conventional machining method. A combined female die was designed so that the rotor could be released easily from the female die after forging. In order to improve the metal flow ability, the isothermal forming technique was introduced to the closed die forging process. On the basis of the rigid-viscoplastic FEM principle, the DEFORM 3D software package was employed to simulate the forming process. The simulation results illustrate that the deformation of different part of the billet is not the same. The material near the entrance of the die cavity is deformed greatly whose strain rate and strain are both large, while the deformation of the material at the billet center is much smaller.展开更多
Hot compression was conducted at a Thermecmaster-Z simulator,at deformation temperatures of 800-1040℃,with strain rates of 0.001-50 s-1 and height reduction of 50%.Grain size of the priorαphase was measured with a L...Hot compression was conducted at a Thermecmaster-Z simulator,at deformation temperatures of 800-1040℃,with strain rates of 0.001-50 s-1 and height reduction of 50%.Grain size of the priorαphase was measured with a Leica LABOR-LUX12MFS/ST microscope to which QUANTIMET 500 software for image analysis for quantitative metallography was linked.According to the present experimental data,a constitutive relationship for a TC6 alloy and a model for grain size of the prior a phase were established based on the Arrhenius'equation and the Yada's equation,respectively.By finite element(FE)simulation,deformation distribution was determined for isothermal forging of a TC6 aerofoil blade at temperatures of 860-940℃and hammer velocities of 9-3000.0 mm/min.Meanwhile,the grain size of the priorαphase is simulated during isothermal forging of the TC6 aerofoil blade,by combining FE outputs with the present grain size model.The present results illustrate the grain size and its distribution in the priorαphase during the isothermal forging of the TC6 aerofoil blade.The simulated results show that the height reduction,deformation temperature,and hammer velocity have significant effects on distribution of the equivalent strain and the grain size of the priorαphase.展开更多
In order to investigate the formability of metal material in semisolid state, a series of experiments were carried out by thixo-forging the complex part of aluminum alloy AlSi7Mg. Through changing the upper punch, alu...In order to investigate the formability of metal material in semisolid state, a series of experiments were carried out by thixo-forging the complex part of aluminum alloy AlSi7Mg. Through changing the upper punch, aluminum parts with different upper-cup dimensions can be successfully produced. The numerical simulation was conducted for investigating the forming limits of AlSi7Mg during thixo-forging. It is found that the simulation result is in good agreement with the experiment one.展开更多
Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve ...Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve the life of the dies in cold rotary forging.The purpose of this work is to reveal the contact force responses in cold rotary forging through the modelling and simulation.For this purpose,a 3D elastic-plastic dynamic explicit FE model of cold rotary forging is developed using the FE code ABAQUS/Explicit.Through the modelling and simulation,the distribution and evolution of the contact force in cold rotary forging is investigated in detail.The experiment has been conducted and the validity of the 3D FE model of cold rotary forging has been verified.The results show that: 1) The contact force distribution is complex and exhibits an obvious non-uniform characteristic in the radial and circumferential directions; 2) The maximum contact force between the upper die and the workpiece is much larger than that between the lower die and the workpiece; 3) The contact force evolution history is periodic and every period experiences three different stages; 4) The total normal contact force is much larger than the total shear contact force at any given time.展开更多
Traditionally a rotary forging process is a kind of metal forming method where a conic upper die, whose axis is deviated an angle from the axis of machine, forges a billet continuously and partially to finish the whol...Traditionally a rotary forging process is a kind of metal forming method where a conic upper die, whose axis is deviated an angle from the axis of machine, forges a billet continuously and partially to finish the whole deformation. For the rotary forging process simulation, more researches were focused on simulating the simple stage forming process with axisymmetric part geometry. Whereas in this paper, the upper die is not cone-shaped, and the billet is non-axisymmetric. So the movement of the punch is much more complicated than ever. The 3D FEM simulation models for the preforming ＆ final forming processes are set up aider carefully studying the complicated movement pattern. Deform-3D is used to simulate the material flow, and the boundary nodal resisting forces calculated by the final stage process simulation is used to analyze the final forming die strength. The CAE analysis of the die shows that the design of the final forming die is not reasonable with lower pre-stress which is easy to crack at the critical corners. An optimum die design is also provided with higher pre-stress, and verified by CAE analysis.展开更多
In this paper,a kind of mathematic method for optimizing stretching process of large forgings is proposed.Distributions of effective strain within forged ingots is described by a Gauss function,which is obtained from ...In this paper,a kind of mathematic method for optimizing stretching process of large forgings is proposed.Distributions of effective strain within forged ingots is described by a Gauss function,which is obtained from the simulation of flat-anvil stretching process.Successive stretching is expressed by the superimposing Gauss functions.Optimized stretching process,with both homogeneous and certain strain in the center of forgings,is presented by derivation of this function.The relationship between effective strain and the values of feed is obtained during the successive stretching with a rotation angle of 90° and a feed displacement of 1/2 anvil width.The optimization result is verified by finite element simulation.Optimized value of feed obtained using this method can ensure both uniformity and forging penetration.It provides mathematic model and theoretic basis of optimizing large forging stretching process.展开更多
The variation principle is discussed and Rayleigh-Ritz method is proposed for construction of veloci ty field. A kinematically admissible velocity field based on polynomials was appIied to the determina tion of forgin...The variation principle is discussed and Rayleigh-Ritz method is proposed for construction of veloci ty field. A kinematically admissible velocity field based on polynomials was appIied to the determina tion of forging load and deformed buIge profile during upset forging of blocks. Simulation of upsetforging of rectangular blocks under various friction condjtions was performed. Comparison of the computed results with experiments and FEM shows good agreement. It is shown that this techniquecan be used for 3D simulation of metal forming process.展开更多
基金Projects(51175363,51274149)supported by the National Natural Science Foundation of China
文摘Based on the design of the multi-row sprocket with a new tooth profile,a cold semi-precision forging process for manufacturing 5052 aluminum alloy multi-row sprocket was presented.Through simulating the forging process of 5052 aluminum alloy sprocket billet with 3D rigid-viscoplastic FEM,both the distributions of flow velocity field in axial(U_Z),radial(U_R) and circumferential(U_θ) directions and the curves of velocity component in different deformation regions were respectively obtained.By comparison and analysis of the velocity varying curves,the velocity component relation conditions for filling the die cavity were clarified.It shows that when the die cavity is almost fully filled,the circumferential velocity U_θ increases sharply,implying that U_θplays a key role in fully filling the die cavity.
基金Project(50225518) supported by the National Science Foundation of China for Distinguished Young Scholars Project(02H53061) supported by the Aeronautical Science Foundation of China Project(05-1) supported by the Foundation of State Key Laboratory of Plastic Forming Simulation and Mould Technology
文摘In order to obtain the desired final shape, the blade precision forging requires a reasonable preformed billet which can be obtained from a given final shape by using backward tracing scheme based on FEM. The key technologies of backward tracing scheme based on 3D rigid-viscoplastic FEM were explored, and some valid algorithms or methods were proposed. A velocity field was generated by combining the direct iterative method with Newton-Raphson iterative method, and then the initial velocity field of backward tracing simulation was achieved by reversing the direction of the velocity field. A new method, namely the tracking-fitting-revising method, was proposed and can be used to determinate the criterion of separating a node from die in the backward tracing simulation. The ceasing criterion of the backward tracing simulation is that all the boundary nodes are detached from dies. Based on the above key technologies, the 3D backward tracing simulation system for the blade precision forging was developed, and its feasibility and reliability were verified by forward loading simulation.
文摘The precision forging process is simulated by commercial software Deform 3D using a rigid visco-plastic model to predict the status of metal flow and the distribution of equivalent plastic strain,providing guidance for making decision on the optimal choice of process parameters and mould structure.Trial forging was used to verify the effectiveness of FEM simulation results.
文摘The present paper examines the deformation behavior of solid cylinders of an aluminium alloy metal matrix composite (MMC) undergoing axial compression in a Universal Testing Machine under dry condition. The composite was pre- pared by the stir casting method from LM6 aluminium alloy using silicon carbide particles (SiC) as reinforcing agent. The effect of weight percentage of silicon carbide on microstructure, hardness and upsetting load is studied. The friction factor at die metal interface is evaluated by ring compression tests and its effect on non-uniform deformation is investi- gated. The experimental results are finally compared with those obtained by FEM simulation.
基金Project (2011CB605505) supported by the National Basic Research Program of ChinaProject (2011QNZT041) supported by the freedom explore Program of Central South University,ChinaProject (84088) supported by the and Postdoctoral Foundation Supported Project of Central South University,China
文摘The hot forging of large-scale P/M TiAl alloy billet deformation was investigated based on a joint application of Deform-3D-based numerical simulation and physical simulation techniques.The temperature dependence on the thermal and mechanical properties of the billet was considered and the optimum hot working temperature of packed TiAl alloy was 1150-1200 °C.Based on the simulation,the material flow and thermo mechanical field variables,such as stress,strain,and temperature distribution were obtained and the relationships of load—displacement and load—time were figured out.To verify the validity of the simulation results,the experiments were also carried out in a forging plant,and a pancake with diameter of 150 mm was obtained exhibiting a regular shape.
基金the National Basic Research Program(973) of China (No. 2006CB705400).
文摘A numerical analysis was performed to study the influence of process parameters on the microstructure evolution of IN718 alloy in rotary forging using the finite element method （FEM）. For this purpose, a constitutive equation considering the effects of strain hardening and dynamic softening of IN718 alloy was built. The constitutive equation and microstructure models were implemented into the finite element code to investigate the microstructure evolution during rotary forging subject to large deformations. The simulations were carried out in the ratio of initial height to diameter range 0.2-0.8, the angle of the rocker 3°-7° and the relative feed per revolution range 0.01-0.1 r^-1. The research results revealed the deformation mechanism and the correlation of process parameters with the grain size evolution of IN718 alloy during rotary forging. These provide evidence for the selection of rotary forging parameters.
基金Project(2005400201) supported by the Aeronautical Science Foundation of Liaoning Province,China
文摘In order to eliminate forging defects appearing in production,based on the rigid-viscoplastic FEM principle,the DEFORM3D software package was employed to simulate the forming process of TC4 alloy mounting part and to optimize the process parameters.In this simulation,the temperature dependency of the thermal and mechanical properties of material was considered.Based on the simulation,the metal flow and thermomechanical field variables such as stress and damage are obtained.The simulation results show that the forging defects are caused by improper die dimension and the optimized die dimension was proposed.To verify the validity of simulation results,forging experiments were also carried out in a forging plant.The forging experiments show that the optimized die dimension can ensure the quality of forging part,and it can provide reference to improve and optimize die design process.
文摘The 3D FEM numerical simulation on multi-action precision cold forging technology of universal joint cross and differential spider is done in this article using DEFORM Software, a commercial computer aided engineering software specializing in forming and heat treatment simulation technology, and suitable for cold, warm and hot forging process. The material flow properties, the dynamic variation of stress and strain in the process of deformation and the load-stroke curve have also been achieved. A good consistency is exhibited between simulation results and practical data. Based on the DEFORM simulation results, the optimized procedure has been found for forging a universal joint cross. What should be emphasized here is that a better understanding of practical forging characters and the environmental factors can greatly improve the simulation accuracy thus make the simulation results more reliable.
基金Project(51105287)supported by the National Natural Science Foundation of China
文摘To investigate the effects of billet geometry on the cold precision forging process of a helical gear, six different billet geometries were designed utilizing the relief-hole principle. And the influences of the billet geometry on the forming load and the deformation uniformity were analyzed by three-dimensional （3D） finite element method （FEM） under the commercial software DEFORM 3D. The billet geometry was optimized to meet lower forming load and better deformation uniformity requirement. Deformation mechanism was studied through the distribution of flow velocity field and effective strain field. The forging experiments of the helical gear were successfully performed using lead material as a model material under the same process conditions used in the FE simulations. The results show that the forming load decreases as the diameter of relief-hole do increases, but the effect of do on the deformation uniformity is very complicated. The forming load is lower and the deformation is more uniform when do is 10 mm.
基金Item Sponsored by National Natural Science Foundation of China(51575446)Natural Science Basis Research Plan in Shaanxi Province of China(2016JQ5070)
文摘The microstructure models were integrated into finite element（FE）code,and a three-dimensional（3D）FE analysis on the entire hot forging processes of 300 M steel large components was performed to predict the distributions of effective strain,temperature field and austenite grain size.The simulated results show that the finest grains distribute in the maximum effective strain region because large strain induces the occurrence of dynamic recrystallization.However,coarse macro-grains appear in the minimum effective strain region.Then,300 M steel forging test was performed to validate the results of FE simulation,and microstructure observations and quantitative analysis were implemented.The average relative difference between the calculated and experimental austenite grain size is 7.56%,implying that the present microstructure models are reasonable and can be used to analyze the hot forging processes of 300 M steel.
基金financially supported by the National Natural Science Foundation of China(No.50974016).
文摘Based on the experimental data from hot compression tests on Gleeble 1500 thermal simulator, the revised constitutive equations of spray-formed FGH95 superalloy considering the effect of strain on the material constants were established. The average absolute relative error （AARE） was employed to verify the validity of the constitutive equation, and the value of AARE is 3.85 %. Subsequently, the revised constitutive equations were successfully used to simulate and analyze the deformation behavior, stress distribution, forming loads and temperature distribution in both dies and billet during the isothermal forging process of turbine disk of large dimension （about 400 mm in diameter） by the means of finite element method （FEM）. Moreover, the optimum process parameters are 1,120 ℃ of forging temperature and 0.01 s^-1 of strain rate for the spray-formed FGH95 superalloy turbine disk.
基金supported by the National Natural Science Foundation of China(No.50675014).
文摘Basing on the analysis of the traits of the roll forging process, a system-model of computer simulation has been established. Three-dimensional rigid-plastic FEM has been used for the simulation of the deformation process in the oval and round pass rolling, including the entering, rolling, and separating stages. The analysis was conducted using the Deform-3D ver.5.0 code. The important information concerned with the deformation area characteristic, material flow, and velocity field has been presented. Otherwise, the location of the neutral plane in the deformation area was shown clearly.
文摘The rotary forging process of a disc is simulated by 3-D finite element method.The motion of the rotary the is described as the combination of a revolution round the machine axis and a spin round the rotary die axis. Therefore, the workpiece can be loaded and unloaded partly and cyclically by the cone surface of the rotary the continuously, according with the practical rotary forging process. From the siumulation rasults, the causes of center-thinning during rotary forging of discs are that the locally loading of rotary die made the workpiece center get high radial and tangential tensile stresses, and then the shortening in axial direction and the elongating in tangential and radial direction occur continuous- ly.
文摘The closed die forging(or fully-enclosed die forging) method was employed to form a rotor instead of the conventional machining method. A combined female die was designed so that the rotor could be released easily from the female die after forging. In order to improve the metal flow ability, the isothermal forming technique was introduced to the closed die forging process. On the basis of the rigid-viscoplastic FEM principle, the DEFORM 3D software package was employed to simulate the forming process. The simulation results illustrate that the deformation of different part of the billet is not the same. The material near the entrance of the die cavity is deformed greatly whose strain rate and strain are both large, while the deformation of the material at the billet center is much smaller.
基金The authors thank the finan cial supports from the State Key Foundational Research Plan with Grant No.G2000067206the Teaching and Research Award Fund for Outstanding Young Teachers in Higher Education Insti—tutions of MOE,China,is acknowledged.
文摘Hot compression was conducted at a Thermecmaster-Z simulator,at deformation temperatures of 800-1040℃,with strain rates of 0.001-50 s-1 and height reduction of 50%.Grain size of the priorαphase was measured with a Leica LABOR-LUX12MFS/ST microscope to which QUANTIMET 500 software for image analysis for quantitative metallography was linked.According to the present experimental data,a constitutive relationship for a TC6 alloy and a model for grain size of the prior a phase were established based on the Arrhenius'equation and the Yada's equation,respectively.By finite element(FE)simulation,deformation distribution was determined for isothermal forging of a TC6 aerofoil blade at temperatures of 860-940℃and hammer velocities of 9-3000.0 mm/min.Meanwhile,the grain size of the priorαphase is simulated during isothermal forging of the TC6 aerofoil blade,by combining FE outputs with the present grain size model.The present results illustrate the grain size and its distribution in the priorαphase during the isothermal forging of the TC6 aerofoil blade.The simulated results show that the height reduction,deformation temperature,and hammer velocity have significant effects on distribution of the equivalent strain and the grain size of the priorαphase.
基金supported by the National High-Tech Research and Development Program of China(No.2007AA03Z119)the National Natural Science Foundation of Beijing (No.2072012 and No.2102029 )
文摘In order to investigate the formability of metal material in semisolid state, a series of experiments were carried out by thixo-forging the complex part of aluminum alloy AlSi7Mg. Through changing the upper punch, aluminum parts with different upper-cup dimensions can be successfully produced. The numerical simulation was conducted for investigating the forming limits of AlSi7Mg during thixo-forging. It is found that the simulation result is in good agreement with the experiment one.
基金Project(51105287)supported by the National Natural Science Foundation of ChinaProject(2012BAA08003)supported by the Key Research and Development Project of New Products and New Technologies of Hubei Province,ChinaProject(2013M531750)supported by China Postdoctoral Science Foundation
文摘Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve the life of the dies in cold rotary forging.The purpose of this work is to reveal the contact force responses in cold rotary forging through the modelling and simulation.For this purpose,a 3D elastic-plastic dynamic explicit FE model of cold rotary forging is developed using the FE code ABAQUS/Explicit.Through the modelling and simulation,the distribution and evolution of the contact force in cold rotary forging is investigated in detail.The experiment has been conducted and the validity of the 3D FE model of cold rotary forging has been verified.The results show that: 1) The contact force distribution is complex and exhibits an obvious non-uniform characteristic in the radial and circumferential directions; 2) The maximum contact force between the upper die and the workpiece is much larger than that between the lower die and the workpiece; 3) The contact force evolution history is periodic and every period experiences three different stages; 4) The total normal contact force is much larger than the total shear contact force at any given time.
文摘Traditionally a rotary forging process is a kind of metal forming method where a conic upper die, whose axis is deviated an angle from the axis of machine, forges a billet continuously and partially to finish the whole deformation. For the rotary forging process simulation, more researches were focused on simulating the simple stage forming process with axisymmetric part geometry. Whereas in this paper, the upper die is not cone-shaped, and the billet is non-axisymmetric. So the movement of the punch is much more complicated than ever. The 3D FEM simulation models for the preforming ＆ final forming processes are set up aider carefully studying the complicated movement pattern. Deform-3D is used to simulate the material flow, and the boundary nodal resisting forces calculated by the final stage process simulation is used to analyze the final forming die strength. The CAE analysis of the die shows that the design of the final forming die is not reasonable with lower pre-stress which is easy to crack at the critical corners. An optimum die design is also provided with higher pre-stress, and verified by CAE analysis.
基金the National Science Support Project found by the Ministry of Science and Technology of China (No.2007BAE51B04)
文摘In this paper,a kind of mathematic method for optimizing stretching process of large forgings is proposed.Distributions of effective strain within forged ingots is described by a Gauss function,which is obtained from the simulation of flat-anvil stretching process.Successive stretching is expressed by the superimposing Gauss functions.Optimized stretching process,with both homogeneous and certain strain in the center of forgings,is presented by derivation of this function.The relationship between effective strain and the values of feed is obtained during the successive stretching with a rotation angle of 90° and a feed displacement of 1/2 anvil width.The optimization result is verified by finite element simulation.Optimized value of feed obtained using this method can ensure both uniformity and forging penetration.It provides mathematic model and theoretic basis of optimizing large forging stretching process.
文摘The variation principle is discussed and Rayleigh-Ritz method is proposed for construction of veloci ty field. A kinematically admissible velocity field based on polynomials was appIied to the determina tion of forging load and deformed buIge profile during upset forging of blocks. Simulation of upsetforging of rectangular blocks under various friction condjtions was performed. Comparison of the computed results with experiments and FEM shows good agreement. It is shown that this techniquecan be used for 3D simulation of metal forming process.
