Papers by Author: Xue Wen Chen

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Authors: Xue Wen Chen, Qi Zhang
Abstract: Critical strain is the basis to determine whether the dynamic recrystallization occurs during hot deformation process, it is important for designers to control hot forming process and microstructure of final product. In order to investigate the influence of deformation temperature and strain rate on critical strain of Cr4 steel, hot compression simulation experiment was conducted for Cr4 steel in the temperature range of 750~1200°C and strain rate of 0.002~5S-1 by means of Gleeble−1500D thermo-simulation machine. The results showed that the critical strain increase with decreasing deformation temperature and increasing strain rate. Based on the experimental data and regression analysis method, the mathematical model of the critical strain of Cr4 steel is constructed. The critical strain model provides data support to predict the dynamic recrystallization during Cr4 heavy supporting roller hot forging process.
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Authors: Xue Wen Chen, Dong Won Jung, Ai Xue Sun
Abstract: Technology and die design are very important in the development of forging products due to its great influence on the quality, cost and manufacturing efficiency of the final products as well as the life of the forging die. In the environment of the severe competition, how to improve the quality of forging technology and die design, to reduce the product cost and ultimately to enhance competitiveness of the forging factory are the problems that forging technology and die designer have to solve. In order to improve the quality of forging technology and die design, a design optimization method based on approximate model (response surface model) and FEM technique for hot forging process is proposed in this paper. During design optimization process, finite element analysis is incorporated to calculate the objective function and check the design alternatives. Design of experiment (DOE) method is used to collect sample points and calculate the polynomial coefficients of response surface model, and approximate model is used to calculate the optimum search direction. Finally, a case study is conducted for a gear workpiece hot forging process. The objective function is the degree of uniformity of equivalent-strain, which can be defined as mean square deviation of the equivalent-strain in each element and the average equivalent-strain of all elements, and the design parameters are the initial H0/D0 ratio of billet and the key dimensions of the die. Then the design optimization mathematical model is established. The result shows that the objective function value is dropped from 0.7914 and converges at 0.4843 within 17 iterations, the optimal design parameters are obtained.
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Authors: Xue Wen Chen, Jun Wei Zhao, Dong Won Jung
Abstract: Flanging is a method of sheet metal forming process under combined compressive and tensile conditions using a punch and die to raise closed rims (flanges or collars) on pierced holes. For the flanging product used for the automotive steering part, the thickness of the bottom radius area is very important because of the crack usually occurred during the using process. But during conventional flanging process, the thickness of the rim and the bottom radius area were decreased seriously and make the hole flanging not strong enough to be used. In order to increase the thickness of bottom radius area of the flanging wall, a new method that combines flanging process and cold forging process was proposed in this paper and a special forming die set was designed with a stripper subjected to counter-pressure with an aim to obtain a more substantial flange. FEM software DEFORM 3D was employed to simulate these flanging part forming processes. The results showed the thickness of bottom radius area of the flanging wall was increased and a more substantial flange was obtained.
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Authors: Ting Liu, Xue Wen Chen, Shu Li Pei
Abstract: Static stents is the switch component that plays the role of fixing and supporting. It will received impact, the attrition and reverse function in the work process, which requires high mechanical properties to meet their work requirements. This paper uses the forming technology of "the pre-formation +warm extrusion + cold finishing "to form the static support ,and it carries on the numerical simulation and optimization analysis, which not only improve the work piece performance greatly and reduce the manufacturing cost.
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Authors: Xue Wen Chen, Ze Hu Liu, Jing Li Zhang
Abstract: The main causes of performance variation in tube bending process are variations in the mechanical properties of material, initial tube thickness, coefficient of friction and other forming process parameters. In order to control this performance variation and to optimize the tube bending process parameters, a robust design method is proposed in this paper for the tube bending process, based on the finite element method and the Taguchi method. During the robust design process, the finite element analysis is incorporated to simulate the tube bending process and calculate the objective function value, the orthogonal design method is selected to arrange the simulation experiments and calculate the S/N ratio. Finally, a case study for the tube bending process is implemented. With the objective to control tube crack (reduce the maximum thinning ratio) and its variation, the robust design mathematical model is established. The optimal design parameters are obtained and the maximum thinning ratio has been reduced and its variation has been controlled.
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