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In this paper, a mechanical model of axial and circumferential bidirectional deformation has been developed by considering two factors: roller shape and radial reduction. Since the calibration of the roundness and that of the straightness of pipes are currently separate processes, the established mechanical models are based on a single direction. However, the established bidirectional mechanical model can describe not only the stress-strain distribution of the pipe in deformation to determine the position of the stress concentration but also the deformation curve of the pipe in different directions. As a result, it can serve as a theoretical basis for setting process parameters and optimizing roller shape. A large thin-walled pipe of Al6063 is modeled and then numerically simulated with FEM software of ABAQUS, and the results are compared with the model. Then, the process is fabricated and tested experimentally. The results are compared with the mechanical and numerical models. The distribution of equivalent stress and equivalent strain obtained by the model has a good match with the simulation results, and the maximum relative error is not more than 25%. The axial and circumferential deformation curve calculated by the mechanical model coincides well with the simulation and experimental results, and the maximum error is not greater than 3.0 mm. Obviously, both the experiment and the simulation have verified a superior validity of the model. A mechanical model of axial and circumferential bidirectional deformation has been developed by considering two factors: roller shape and radial reduction. The model can describe not only the stress-strain distribution of pipes in deformation to determine the position of the stress concentration but also the deformation curve of pipes in different directions. It provides a theoretical basis for the setting of process parameters and the optimization of roller shape.
Xueying Huang; Gaochao Yu; Honglei Sun; Jun Zhao. A mechanical model of axial and circumferential bidirectional deformation for large thin-walled pipes in the process of continuous and synchronous calibration of roundness and straightness by three rollers. The International Journal of Advanced Manufacturing Technology 2021, 1 -18.
AMA StyleXueying Huang, Gaochao Yu, Honglei Sun, Jun Zhao. A mechanical model of axial and circumferential bidirectional deformation for large thin-walled pipes in the process of continuous and synchronous calibration of roundness and straightness by three rollers. The International Journal of Advanced Manufacturing Technology. 2021; ():1-18.
Chicago/Turabian StyleXueying Huang; Gaochao Yu; Honglei Sun; Jun Zhao. 2021. "A mechanical model of axial and circumferential bidirectional deformation for large thin-walled pipes in the process of continuous and synchronous calibration of roundness and straightness by three rollers." The International Journal of Advanced Manufacturing Technology , no. : 1-18.
Submarine pipeline is a key part in the development of deep sea and ultra-deep sea oil and gas. In order to reduce the ovality of pipes and improve their compressive strength, a two-roller continuous calibration (TRCC) process by compression is proposed. A springback analysis of compress bending is carried out, and an analytical model is established, which predicts ovality after calibration and provides a theoretical basis for roller shape design and process parameter formulation. Numerical simulation and physical experiments are carried out. The distribution of stress and strain is analyzed. The effects of initial ovality, reduction ratio and initial placement angle on the ovality after calibration are studied. When the reduction ratio is about 1%, the ovality is optimal. The theoretical analysis shows that the ovality after calibration is about 0.03%, and the ovality after calibration by numerical simulation and experiment is less than 0.45%, proving the feasibility of the process.
Deping Peng; Zhongwang Gong; Shumin Zhang; Gaochao Yu. Two-Roller Continuous Calibration Process by Compression for Submarine Pipelines. Symmetry 2021, 13, 1224 .
AMA StyleDeping Peng, Zhongwang Gong, Shumin Zhang, Gaochao Yu. Two-Roller Continuous Calibration Process by Compression for Submarine Pipelines. Symmetry. 2021; 13 (7):1224.
Chicago/Turabian StyleDeping Peng; Zhongwang Gong; Shumin Zhang; Gaochao Yu. 2021. "Two-Roller Continuous Calibration Process by Compression for Submarine Pipelines." Symmetry 13, no. 7: 1224.
The intelligent production of sheet metal is a comprehensive technology involving control science, computer science, and sheet metal production. Intelligent rolling is an important development in the production process of sheet metal. In this paper, a new symmetrical four-roller bending (SFRB) process is introduced, which consists of feeding, pre-bending, reverse roll bending, second bending, and forward roll bending and unloading. A control strategy is proposed for the process, including on-line monitoring of curvature, on-line identification of the springback law, on-line prediction of final reduction, and control strategy. A convenient and reliable on-line curvature monitoring method is proposed. The quantitative relationship between the reduction and the curvature, in the form of a quadratic function, was established by physical experiments and numerical simulation, and the online identification of the springback law was realized. An on-line prediction method of the final reduction is proposed, and the determination principle of the reduction of three pre-bending processes is given. Finally, the control strategy of the SFRB process was verified by physical experiments. The relative error of the curvature radius of the final formed parts can be controlled within 0.8%. This research provides new insights into intelligent rolling.
Hongqiang Cao; Gaochao Yu; Chunfang Yang; Jun Zhao. Research on a Control Strategy of the Symmetrical Four-Roller Bending Process Based on Experiment and Numerical Simulation. Symmetry 2021, 13, 940 .
AMA StyleHongqiang Cao, Gaochao Yu, Chunfang Yang, Jun Zhao. Research on a Control Strategy of the Symmetrical Four-Roller Bending Process Based on Experiment and Numerical Simulation. Symmetry. 2021; 13 (6):940.
Chicago/Turabian StyleHongqiang Cao; Gaochao Yu; Chunfang Yang; Jun Zhao. 2021. "Research on a Control Strategy of the Symmetrical Four-Roller Bending Process Based on Experiment and Numerical Simulation." Symmetry 13, no. 6: 940.
The parameter solving method for springback control mainly depends on theoretical models and numerical simulation. However, many assumptions are adopted in the theoretical model, which inevitably lead to prediction error in practical application. Therefore, for bending and straightening process, a difference iterative compensation method and secant iterative compensation method based on the implicit equation were proposed. In these methods, the deflection and curvature were taken as the control parameter of iterative compensation, and the convergence of deflection was also verified by theory. According to the proposed iterative compensation strategy, an automatic straightening equipment was developed. On this basis, the bending and straightening of shafts and stretch-bending experiments were carried out to demonstrate the efficiency and reliability of the proposed iterative compensation strategy. The results show that the iterative compensation methods can predict the next compensation value based on the springback value of each tests, so that the target value with the error of less than 2% can be obtained with 2–3 iterations. Moreover, the proposed methods are independent on the material properties and mechanical model, and has high convergence precision for the springback compensation problem.
Zhenkai Mu; Rui Ma; Jun Zhao; Gaochao Yu; Honglei Sun. Research on iterative compensation method for springback control based on implicit equation. International Journal of Material Forming 2021, 14, 1097 -1108.
AMA StyleZhenkai Mu, Rui Ma, Jun Zhao, Gaochao Yu, Honglei Sun. Research on iterative compensation method for springback control based on implicit equation. International Journal of Material Forming. 2021; 14 (5):1097-1108.
Chicago/Turabian StyleZhenkai Mu; Rui Ma; Jun Zhao; Gaochao Yu; Honglei Sun. 2021. "Research on iterative compensation method for springback control based on implicit equation." International Journal of Material Forming 14, no. 5: 1097-1108.
In order to determine the stress–strain response in the diffuse necking for low carbon steels, the evolution of the diffuse necking region and the distributions of stress and strain in the narrowest cross-section are analyzed comprehensively based on 3D-DIC and FE simulation. Three parabolic functions are adopted to simplify the diffuse necking deformation: the shape of the necking region is parabolic, the distributions of stress and strain in the narrowest cross-section are also parabolic. A hardening model for solving the uniaxial tensile true stress and strain in the diffuse necking is established. Uniaxial tensile tests of four kinds of low carbon steel sheets and three typical anisotropic directions have been carried out to verify the reliability of the developed model. The numerical simulation results show that the uniaxial tensile load–elongation curves based on the hardening model are in good agreement with the experimental results, with an error of less than 1.3%. The true stress and strain in the diffuse necking can be determined easily by interpreting the tensile curve and measuring the shape of necking region. It avoids the difficulty and time-consuming of the inverse methods. This study can provide a valuable reference for establishing theoretical models to acquire true stress–strain curves over large range of strains for anisotropic sheet metals.
Zhenkai Mu; Jun Zhao; Gaochao Yu; Xueying Huang; Qingdang Meng; Ruixue Zhai. Hardening model of anisotropic sheet metal during the diffuse instability necking stage of uniaxial tension. Thin-Walled Structures 2020, 159, 107198 .
AMA StyleZhenkai Mu, Jun Zhao, Gaochao Yu, Xueying Huang, Qingdang Meng, Ruixue Zhai. Hardening model of anisotropic sheet metal during the diffuse instability necking stage of uniaxial tension. Thin-Walled Structures. 2020; 159 ():107198.
Chicago/Turabian StyleZhenkai Mu; Jun Zhao; Gaochao Yu; Xueying Huang; Qingdang Meng; Ruixue Zhai. 2020. "Hardening model of anisotropic sheet metal during the diffuse instability necking stage of uniaxial tension." Thin-Walled Structures 159, no. : 107198.
Isothermal hot compression tests of 20Cr2Ni4A alloy steel were performed under temperatures of 973–1273 K and strain rates of 0.001–1 s−1. The behavior of the flow stress of 20Cr2Ni4A alloy steel at warm and hot temperatures is complicated because of the influence of the work hardening, the dynamic recovery, and the dynamic recrystallization. Four constitutive equations were used to predict the flow stress of 20Cr2Ni4A alloy steel, including the original strain-compensated Arrhenius-type (osA-type) equation, the new modified strain-compensated Arrhenius-type (msA-type) equation, the original Hensel–Spittel (oHS) equation and the modified Hensel–Spittel (mHS) equation. The msA-type and mHS are developed by revising the deformation temperatures, which can improve prediction accuracy. In addition, we propose a new method of solving the parameters by combining a linear search with multiple linear regression. The new solving method is used to establish the two modified constitutive equations instead of the traditional regression analysis. A comparison of the predicted values based on the four constitutive equations was performed via relative error, average absolute relative error (AARE) and the coefficient of determination (R2). These results show the msA-type and mHS equations are more accurate and efficient in terms of predicting the flow stress of the 20Cr2Ni4A steel at elevated temperature.
Haoran Wang; Wei Wang; Ruixue Zhai; Rui Ma; Jun Zhao; Zhenkai Mu. Constitutive Equations for Describing the Warm and Hot Deformation Behavior of 20Cr2Ni4A Alloy Steel. Metals 2020, 10, 1169 .
AMA StyleHaoran Wang, Wei Wang, Ruixue Zhai, Rui Ma, Jun Zhao, Zhenkai Mu. Constitutive Equations for Describing the Warm and Hot Deformation Behavior of 20Cr2Ni4A Alloy Steel. Metals. 2020; 10 (9):1169.
Chicago/Turabian StyleHaoran Wang; Wei Wang; Ruixue Zhai; Rui Ma; Jun Zhao; Zhenkai Mu. 2020. "Constitutive Equations for Describing the Warm and Hot Deformation Behavior of 20Cr2Ni4A Alloy Steel." Metals 10, no. 9: 1169.
Isothermal hot compression tests of TC4–DT titanium alloy were performed under temperatures of 1203–1293 K and strain rates of 0.001–10 s−1. The purpose of this study is to develop a new high-precision modified constitutive model that can describe the deformation behavior of TC4–DT titanium alloy. Both the modified strain-compensated Arrhenius-type equation and the modified Hensel–Spittel equation were established by revising the strain rate. The parameters in the above two modified constitutive equation were solved by combining regression analysis with iterative methods, which was used instead on the traditional linear regression methods. In addition, both the original strain-compensated Arrhenius-type equation and Hensel–Spittel equation were established to compare with the new modified constitutive equations. A comparison of the predicted values based on the four constitutive equations was performed via relative error, average absolute relative error (AARE) and the correlation coefficient (R). These results show the modified Arrhenius-type equation and the modified Hensel–Spittel equation is more accurate and efficient with a similar prediction accuracy. The AARE-value of the two modified constitutive equation is relatively low under various strain rates and their fluctuation is small as the strain rate changes.
Haoran Wang; Chunge Wang; Muyu Li; Rui Ma; Jun Zhao. Constitutive Equations for Describing the Hot Compressed Behavior of TC4–DT Titanium Alloy. Materials 2020, 13, 3424 .
AMA StyleHaoran Wang, Chunge Wang, Muyu Li, Rui Ma, Jun Zhao. Constitutive Equations for Describing the Hot Compressed Behavior of TC4–DT Titanium Alloy. Materials. 2020; 13 (15):3424.
Chicago/Turabian StyleHaoran Wang; Chunge Wang; Muyu Li; Rui Ma; Jun Zhao. 2020. "Constitutive Equations for Describing the Hot Compressed Behavior of TC4–DT Titanium Alloy." Materials 13, no. 15: 3424.
The isothermal compressions of Mg-Gd-Y-Zn-Zr alloy in a temperature range of 653–773 K and strain rate range of 0.001-1 s−1 were conducted. The Arrhenius-type equation is widely applied to describe the complex behavior of the flow stress at elevated temperatures. Linear regression is the most common method to solve material constants of the Arrhenius-type equation in previous research. In prevent study, a new method is proposed to solve material constants. The new method combines an iterative method with regression analysis, and it transforms the Arrhenius-type equation into a system of equations of two equations. Moreover, to improving convergence speed, we introduce an offset error into one equation in the system of equations and propose methods to determine the initial guess. A comparative study has been made between the new method and the regression method. The result shows compared with the regression method, the new method improves the prediction accuracy of the Arrhenius-type equation, and it decreases the number of regression operations when the same average absolute relative error (AARE) value is used as a criterion.
Haoran Wang; Zhiyuan Zhang; Ruixue Zhai; Rui Ma; Jun Zhao. New method to develop High temperature constitutive model of metal based on the Arrhenius-type model. Materials Today Communications 2020, 24, 101000 .
AMA StyleHaoran Wang, Zhiyuan Zhang, Ruixue Zhai, Rui Ma, Jun Zhao. New method to develop High temperature constitutive model of metal based on the Arrhenius-type model. Materials Today Communications. 2020; 24 ():101000.
Chicago/Turabian StyleHaoran Wang; Zhiyuan Zhang; Ruixue Zhai; Rui Ma; Jun Zhao. 2020. "New method to develop High temperature constitutive model of metal based on the Arrhenius-type model." Materials Today Communications 24, no. : 101000.
Aiming at the forming efficiency and roundness of the longitudinal submerged arc welded (LSAW) pipes in JCO (J-shape to C-shape to O-shape) forming process, this paper proposes a four-point air bending process. Compared with the traditional three-point air bending process, The new process can provide a more uniform bending moment, does not need to crimp the edges of steel sheet, shorten the residual straight segment length, and lengthen the forming length in single pass. The mechanical model is established to analyze the static equilibrium conditions and elastic–plastic deformation. The process is simulated by using the software package ABAQUS, to find the maximum punch spacing, and further determine the formulation principles of other process parameters. In addition, a contour detection method for the LSAW pipes in forming process is proposed based on machine vision (planar-array CCD camera produced by Gray Point Corporation, Vancouver, Canada). This method can not only quickly detect the contour of each pass, but also splice the detected contours together to obtain the overall contour with the given splicing algorithm. According to the measured contour, the bending angle, radius, and roundness can be calculated, to correct the punch reduction in the next pass and improve the forming accuracy of the pipes. Finally, an experimental system is designed to verify the proposed four-point bending JCO forming process and contour detection method. The result shows that the error between the contour detection method and CMM (coordinate measuring machine) is less than 0.5% for the overall contour, the two experimental pipes require 13 and 15 passes respectively, the roundness of pipes are less than 1.1%, which is much better than that of traditional three-point bending JCO forming process.
Zhiyuan Zhang; Haoran Wang; Gaochao Yu; Jun Zhao; Wang; Yu; Zhao. Research on Four-Point Air Bending Process and Contour Detection Method for JCO Forming Process of LSAW Pipes. Metals 2019, 9, 859 .
AMA StyleZhiyuan Zhang, Haoran Wang, Gaochao Yu, Jun Zhao, Wang, Yu, Zhao. Research on Four-Point Air Bending Process and Contour Detection Method for JCO Forming Process of LSAW Pipes. Metals. 2019; 9 (8):859.
Chicago/Turabian StyleZhiyuan Zhang; Haoran Wang; Gaochao Yu; Jun Zhao; Wang; Yu; Zhao. 2019. "Research on Four-Point Air Bending Process and Contour Detection Method for JCO Forming Process of LSAW Pipes." Metals 9, no. 8: 859.
In order to reduce the straight edge section and simplify process flow, a new symmetrical four-roller bending process is proposed, and its optimum forming process is determined. The main procedure composes of feeding, pre-bending, reverse roll bending, final bending, positive roll bending, unloading, and springback. It has advantages of less production procedure, small remaining straight edge, and simple equipment structure. Three methods are adopted to study the process, i.e., theoretical analysis, numerical simulation, and physical experiment. According to the theory of elastoplastic and geometric relation, the relationship between the reduction of the upper roller and the curvature radius before and after springback is established, and the reduction of the upper roller can be predicted. The symmetrical four-roller bending process is simulated by ABAQUS software. The distribution of stress and strain is analyzed, and the theoretical curvature radius and the simulated curvature radius are compared. The rolling part is obtained from simulation with an ovality of 0.43% and only 1.5 times the thickness of the remaining straight edge. The symmetrical four-roller bending machine is designed, and the ovality of the rolling part from experiment is less than 5%, and the minimum is only 1.74%. The error of most curvature radius is less than 0.5%. Numerical simulation and physical experiments both prove the feasibility of the method. The effect of the process parameters on the curvature after springback is studied by a single variable method. This process provides a new idea for pipe production and helps improve the rolling quality.
Gaochao Yu; Jun Zhao; Changfu Xu. Development of a symmetrical four-roller bending process. The International Journal of Advanced Manufacturing Technology 2019, 104, 4049 -4061.
AMA StyleGaochao Yu, Jun Zhao, Changfu Xu. Development of a symmetrical four-roller bending process. The International Journal of Advanced Manufacturing Technology. 2019; 104 (9-12):4049-4061.
Chicago/Turabian StyleGaochao Yu; Jun Zhao; Changfu Xu. 2019. "Development of a symmetrical four-roller bending process." The International Journal of Advanced Manufacturing Technology 104, no. 9-12: 4049-4061.
In the over-bend straightening process of longitudinally submerged arc welding (LSAW) pipes, the cross section tends to be distorted due to the axial curvature variation in the reverse elastic-plastic bending. Based on the minimum work principle, a analytical model of the cross-sectional distortion of the curved pipe with initial curvature in the reverse axial elastoplastic bending is established, and the prediction error is not more than 10% compared with the experimental value of the maximum distortion coefficient. Especially for smaller deformations and thinner pipes, the prediction accuracy is higher. Compared to ovality, the maximum distortion coefficient with a smaller error can be used as an effective prediction parameter. In addition, the application of this prediction model is analyzed by an example of a straightness-offgrade LSAW pipe. The results show that the maximum value and position of cross section with most serious distortion can be determined once the initial curvature of a curved pipe is measured, which can be compared with the standard to adjust the shape of the straightening tools and process parameters.
Chunge Wang; Zhiyuan Zhang; Ruixue Zhai; Gaochao Yu; Jun Zhao. Cross-sectional distortion of LSAW pipes in over-bend straightening process. Thin-Walled Structures 2018, 129, 85 -93.
AMA StyleChunge Wang, Zhiyuan Zhang, Ruixue Zhai, Gaochao Yu, Jun Zhao. Cross-sectional distortion of LSAW pipes in over-bend straightening process. Thin-Walled Structures. 2018; 129 ():85-93.
Chicago/Turabian StyleChunge Wang; Zhiyuan Zhang; Ruixue Zhai; Gaochao Yu; Jun Zhao. 2018. "Cross-sectional distortion of LSAW pipes in over-bend straightening process." Thin-Walled Structures 129, no. : 85-93.
Application of Open-die Warm Extrusion Technique in Spur Gear Manufacturing | InTechOpen, Published on: 2018-02-28. Authors: Wei Wang and Jun Zhao
Wei Wang; Jun Zhao. Application of Open-die Warm Extrusion Technique in Spur Gear Manufacturing. Extrusion of Metals, Polymers and Food Products 2018, 1 .
AMA StyleWei Wang, Jun Zhao. Application of Open-die Warm Extrusion Technique in Spur Gear Manufacturing. Extrusion of Metals, Polymers and Food Products. 2018; ():1.
Chicago/Turabian StyleWei Wang; Jun Zhao. 2018. "Application of Open-die Warm Extrusion Technique in Spur Gear Manufacturing." Extrusion of Metals, Polymers and Food Products , no. : 1.
Aiming at the low efficiency of three-point mold bending straightening, a new method of three-roll continuous straightening is proposed in this paper, which is full in consideration of the geometric features and bending characteristics of LSAW pipes. Using the characteristics of the roll straightening device, a straightness detection method for large pipes is proposed just by adding a laser displacement sensor, and the calculation model for overall deflection based on local deflection is established. Based on the detected deflection data, a piecewise fitting algorithm with constraints by introducing the Kuhn-Tucker condition is proposed for straightness calculation, and a simple polynomial fitting method with fourth order is determined for the calculation of curvature and straightening moment. Further, using the semi-automatic experimental prototype for small pipes, the deflection detection experiments show that the overall deflection error is less than 3.5% compared with that of CMM, the piecewise fitting results show that the ideal order of the mid-segment is 10-th, and the three-roll continuous straightening experiments show that the novel method can correct the straightness to less than 0.2%, meeting the standard requirements.
Chunge Wang; Gaochao Yu; Wei Wang; Jun Zhao. Deflection detection and curve fitting in three-roll continuous straightening process for LSAW pipes. Journal of Materials Processing Technology 2017, 255, 150 -160.
AMA StyleChunge Wang, Gaochao Yu, Wei Wang, Jun Zhao. Deflection detection and curve fitting in three-roll continuous straightening process for LSAW pipes. Journal of Materials Processing Technology. 2017; 255 ():150-160.
Chicago/Turabian StyleChunge Wang; Gaochao Yu; Wei Wang; Jun Zhao. 2017. "Deflection detection and curve fitting in three-roll continuous straightening process for LSAW pipes." Journal of Materials Processing Technology 255, no. : 150-160.
In this paper, a series of problems about the three-roller setting round process are studied. The theoretical analysis of increasing the roundness by three-roller bending is carried out, which shows that every pipe-wall segment alternately experiences multiple times of reciprocating bending, then the process mechanism of the three-roller setting round process is elaborated upon. It is proven by the mathematical induction method that the difference of the initial curvature of each pipe-wall segment can be eliminated and unified by multiple times of reciprocating bending. The experimental results show that with the increase of the upper roller reduction and the decrease of the elastic area ratio, the residual ovality of the pipe decreases gradually. When the elastic area ratio reaches about 20 %, the residual ovality can be controlled at around 0.35 %, which is far less than the requirement of American Petroleum Institute (API) standard. The quantitative relationships between the reduction and the curvature variation and the elastic area ratio are established, so the prediction of the reduction can be realized. However, in order to get the pipe of high precision, it is necessary to greatly increase the tonnage of a three-roller setting round device, which is an aspect that the setting round equipment manufacturers and pipe manufacturers need to notice. In addition, the residual ovality has nothing to do with the initial ovality and has little relation with the lower roller spacing, and it mainly depends on the elastic area ratio and the reasonable process parameters.
Gaochao Yu; Jun Zhao; Ruixue Zhai; Rui Ma; Chunge Wang. Theoretical analysis and experimental investigations on the symmetrical three-roller setting round process. The International Journal of Advanced Manufacturing Technology 2016, 94, 45 -56.
AMA StyleGaochao Yu, Jun Zhao, Ruixue Zhai, Rui Ma, Chunge Wang. Theoretical analysis and experimental investigations on the symmetrical three-roller setting round process. The International Journal of Advanced Manufacturing Technology. 2016; 94 (1-4):45-56.
Chicago/Turabian StyleGaochao Yu; Jun Zhao; Ruixue Zhai; Rui Ma; Chunge Wang. 2016. "Theoretical analysis and experimental investigations on the symmetrical three-roller setting round process." The International Journal of Advanced Manufacturing Technology 94, no. 1-4: 45-56.
20Cr2Ni4A steel is a kind of representative high-strength alloy carburizing steel with excellent comprehensive mechanical performance, especially it is known for its prominent hardenability and obdurability. The compression tests of 20Cr2Ni4A steel are implemented on a Gleeble-3500 thermal simulation machine at different deformation temperatures of 1073.15, 1173.15, and 1273.15 K, with strain rates of 0.001, 0.01, 0.1, and 1 s−1. The Arrhenius-type constitutive equation and Zener–Hollomon parameter are determined to describe the deformation behavior of 20Cr2Ni4A steel. The kinetic and kinematic models of dynamic recrystallization are deduced to describe the dynamic recrystallization behavior of 20Cr2Ni4A steel, the dynamic recrystallization grain size model of 20Cr2Ni4A steel is also constructed.
Wei Wang; Jun Zhao; Rui Xue Zhai; Rui Ma. Arrhenius-Type Constitutive Model and Dynamic Recrystallization Behavior of 20Cr2Ni4A Alloy Carburizing Steel. steel research international 2016, 88, 1 .
AMA StyleWei Wang, Jun Zhao, Rui Xue Zhai, Rui Ma. Arrhenius-Type Constitutive Model and Dynamic Recrystallization Behavior of 20Cr2Ni4A Alloy Carburizing Steel. steel research international. 2016; 88 (3):1.
Chicago/Turabian StyleWei Wang; Jun Zhao; Rui Xue Zhai; Rui Ma. 2016. "Arrhenius-Type Constitutive Model and Dynamic Recrystallization Behavior of 20Cr2Ni4A Alloy Carburizing Steel." steel research international 88, no. 3: 1.
The inner-wall loading by three-point bending about thin-walled pipe is an elastic-plastic secondary indeterminate problem in the symmetrical three-roller setting round process. In this study, the shifting of the tangent point between the pipe and lower roller is ignored. The bilinear hardening material model is adopted, and the static equilibrium condition, physical relationship of elastic-plastic deformation, and deformation compatibility condition are taken into account. Based on the geometrical discrete idea, a semi-circular pipe is meshed equably into N micro-pipe-wall elements with same geometric parameters along the circumferential direction. Deformation characteristics of each element are calculated, and then the deformation history response of the whole pipe is resolved by the load increment method. The finite element model of static bending in three-roller setting round process is established by using the software package ABAQUS. The theoretical and simulated results show that the cross section of pipe has two positive bending regions and two reverse bending regions; the maximum bending curvature appears in the bottom section of pipe, the minimum bending curvature appears in the section corresponding to the tangent point of the pipe and lower roller. The quantitative relationships between the upper roller load, maximum(minimum) bending curvature and reduction are given. Finally, the reliability of theoretical calculation is proved by numerical simulation.
Gaochao Yu; Jun Zhao; Feiping Zhao. Elastic-plastic secondary indeterminate problem for thin-walled pipe through the inner-wall loading by three-point bending. Mechanics Based Design of Structures and Machines 2016, 45, 219 -238.
AMA StyleGaochao Yu, Jun Zhao, Feiping Zhao. Elastic-plastic secondary indeterminate problem for thin-walled pipe through the inner-wall loading by three-point bending. Mechanics Based Design of Structures and Machines. 2016; 45 (2):219-238.
Chicago/Turabian StyleGaochao Yu; Jun Zhao; Feiping Zhao. 2016. "Elastic-plastic secondary indeterminate problem for thin-walled pipe through the inner-wall loading by three-point bending." Mechanics Based Design of Structures and Machines 45, no. 2: 219-238.
The warm deformation behavior of 20Cr2Ni4A steel and the relative constitutive equation are ascertained to support the technical study. Factors that influence the warm extrusion of spur gear are analyzed by using the numerical simulation method. Among the various influencing factors, the lubricating condition, entrance angle, and initial blank size are the crucial factors. Spur gears with a good quality can be one-step formed by warm extrusion under a good lubricating condition (friction factor less than 0.3). Nevertheless, this kind of lubricating condition is very hard to be achieved in a real production environment. “Variable contour two-step warm extrusion” is proposed, in order to obtain a good forming result in a poor lubricating condition. Pre-extrusion is firstly implemented by a die which contour is enlarged from the final-toothed contour for the tooth forming, and then the workpiece is turned around to implement the finish extrusion by a die with the final-toothed contour for insufficient section compensation and tooth sizing. Accuracy of the finished gear obtained through this process is tested; the maximum mean error of single tooth is 15.5 μm.
Wei Wang; Jun Zhao; Ruixue Zhai; Rui Ma. Variable contour two-step warm extrusion forming of spur gear and the deformation behavior of 20Cr2Ni4A steel. The International Journal of Advanced Manufacturing Technology 2016, 88, 3163 -3173.
AMA StyleWei Wang, Jun Zhao, Ruixue Zhai, Rui Ma. Variable contour two-step warm extrusion forming of spur gear and the deformation behavior of 20Cr2Ni4A steel. The International Journal of Advanced Manufacturing Technology. 2016; 88 (9-12):3163-3173.
Chicago/Turabian StyleWei Wang; Jun Zhao; Ruixue Zhai; Rui Ma. 2016. "Variable contour two-step warm extrusion forming of spur gear and the deformation behavior of 20Cr2Ni4A steel." The International Journal of Advanced Manufacturing Technology 88, no. 9-12: 3163-3173.
This paper presents a cold stamping process for single-welded elbows, which has advantages of no heating, no adjusting roundness and single weld. This process is particularly suitable for forming large diameter thin-walled deep-water pipeline elbows. The main procedure composes of blanking, machining groove, U-forming, O-forming, welding, and removing excess material. The initial blank is calculated inversely by Dynaform software, and then the finite element model of cold stamping process is developed to simulate the deformation process under different process parameters by ABAQUS software. The forming tools are designed and the experiments are carried out. Finally, the U-forming process and the O-forming process are analyzed and possible causes of the elbow wrinkling are studied. When the compression ratio is 0.75 % and the clearance between the U-punch and die is 1.05 times of blank thickness, the formed pipe elbow will be with good quality. The geometric parameters of formed elbows from FEM and the experiment are tested, the results show that the ovality is less than 0.6 %, the maximum thickening rate is less than 12 %, and the maximum thinning rate is less than 8 %. All of these verify the feasibility of the cold stamping process for forming the single-welded elbow.
Gaochao Yu; Jun Zhao; Chunge Wang; Ruixue Zhai; Rui Ma. Development of a cold stamping process for forming single-welded elbows. The International Journal of Advanced Manufacturing Technology 2016, 88, 1911 -1921.
AMA StyleGaochao Yu, Jun Zhao, Chunge Wang, Ruixue Zhai, Rui Ma. Development of a cold stamping process for forming single-welded elbows. The International Journal of Advanced Manufacturing Technology. 2016; 88 (5-8):1911-1921.
Chicago/Turabian StyleGaochao Yu; Jun Zhao; Chunge Wang; Ruixue Zhai; Rui Ma. 2016. "Development of a cold stamping process for forming single-welded elbows." The International Journal of Advanced Manufacturing Technology 88, no. 5-8: 1911-1921.
The static bending deformation of three-roller setting round process is an elastic-plastic secondary indeterminate problem, and belongs to the plane bending deformation. This paper adopts a bilinear material model. In consideration of shifting of the tangent points between the pipe and the lower rollers, the static equilibrium conditions, the physical relationships of elastic-plastic deformation, the deformation compatibility conditions, and the constraint conditions are analyzed comprehensively. By applying the discrete method, a semi-circular pipe is meshed equably into N micro-pipe-wall elements with the same geometric parameters. Deformation characteristics of each micro-pipe-wall element are calculated, and then the deformation history responses of the whole pipe are resolved by applying the load increment method, based on the variable step size, and the experimental apparatus is further designed to verify the theoretical model. Finally, the effects of various process parameters on the upper roller load and bending curvature are studied. The results show that the static bending deformation can be assumed to be a pure bending process; the cross section of the pipe has two positive bending regions and two reverse bending regions; the upper roller diameter and the lower rollers spacing are the major factors for the upper roller load and the bending curvature; the dynamic roll bending process can be simplified into a static to-and-fro bending process.
Jun Zhao; Gaochao Yu; Rui Ma. A mechanical model of symmetrical three-roller setting round process: The static bending stage. Journal of Materials Processing Technology 2016, 231, 501 -512.
AMA StyleJun Zhao, Gaochao Yu, Rui Ma. A mechanical model of symmetrical three-roller setting round process: The static bending stage. Journal of Materials Processing Technology. 2016; 231 ():501-512.
Chicago/Turabian StyleJun Zhao; Gaochao Yu; Rui Ma. 2016. "A mechanical model of symmetrical three-roller setting round process: The static bending stage." Journal of Materials Processing Technology 231, no. : 501-512.
A forming process of spur gears by warm extrusion is proposed, the forming defects existing in this process such as the insufficient section of gear face and the underfilling of gear tooth which result in the geometrical dimensions of gear tooth are substandard or machining allowance is overlarge are discussed by using the numerical simulation method. The main reason causing the insufficient section of gear face is unbalanced velocity field distribution during the extrusion process; the lubricating condition and the die structure are two decisive factors. The die structure and extrusion speed are optimized by using the Response Surface Method with the goals of defects control and machining allowance optimization. The influence rules of PVR (Profile Variable Ratio of entrance section), PVR′ (Profile Variable Rate of entrance section) and the extrusion speed on forming quality are investigated, the prediction models of the machining allowance of gear face, tooth flank and tip are established. The accuracy of prediction models is verified by implementing numerical simulation and experiment. This work provides one of the feasible ways to manufacture spur gears with the whole gear teeth in the field of plastic forming.
Wei Wang; Jun Zhao; Ruixue Zhai. A forming technology of spur gear by warm extrusion and the defects control. Journal of Manufacturing Processes 2016, 21, 30 -38.
AMA StyleWei Wang, Jun Zhao, Ruixue Zhai. A forming technology of spur gear by warm extrusion and the defects control. Journal of Manufacturing Processes. 2016; 21 ():30-38.
Chicago/Turabian StyleWei Wang; Jun Zhao; Ruixue Zhai. 2016. "A forming technology of spur gear by warm extrusion and the defects control." Journal of Manufacturing Processes 21, no. : 30-38.