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이영선(Y. S. Lee),정택우(T. W. Jung),정성환(S.H.Jung),문영훈(Y.H.Moon) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
Precision forging of helical gear is very difficult because of helix angle. Dimensional tolerance of tooth profile should be from die through forged part into heat-treated part to get the required dimensional accuracy. Additionally, die machining also is very much difficult because helix angle is not accord with vertical axis. Therefore, a more precise study about dimensions is necessary to get the precise part, considering the dimensional changes from forging die to final part. In this paper, strategy investigating the dimensional changes of die and part are illustrated to investigate the effect of several features including die dimension at each forging step and heat-treatment on final part accuracy. The dimension of forged part is checked at each stage as machined die, cold forged, and post-heat-treatment steps.
헬리컬 기어 치수정밀도 향상을 위한 전방압출 공정설계에 관한 연구
정택우(T. W. Jung),이영선(Y. S. Lee),문영훈(Y. H. Moon),이일환(I. H. Lee),최석탁(S. T. Choi),강성훈(S. H. Kang) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
This work was focused on improvement of the filling degree of the material within the die during forward extrusion of helical gear. For this, the effects of billet, punch and mandrel shapes on the materials flow during helical gear forging were investigated using finite element simulations. In the work of literature, the helical gear was produced by forward extrusion with combined spur and helical gear dies using the tube-shape material. However, simulation results showed that the material was not completely filled within the die and the resultant dimensional error between the die and forged helical gear is very high. In order to reduce the error between the two, forward extrusion process of helical gear with tapered mandrel was proposed. It was found from simulation results that the dimensional error is dramatically decreased in case that tapered mandrel is used in forward extrusion of helical gear.
Study on Dimensional Changes of Helical Gear for Extrusion Process
T. W. Jung(정택우),Y. S. Young(이영선),Y. H. Moon(문영훈) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.10
Dimensional change of tooth profile was investigated by experimental and rEM analysis on cold extrusion and heat treatment of helical gear. Especially, the three-dimensional elasto-plastic finite element method was used to generate the criteria for dimensional change value of helical gear cold extrusion and following heat treatment. The effect of element size was studied related with elastic recovery of forged part and forging tools. The change of tooth profile also by heat treatment was investigated. Calculated values were compared with measured values. From the results, we suppose to use the FEM analysis analyzing the dimensional accuracy of final part on helical gear cold forging.
Clad Sheet(Mg-Al-SUS) 성형성에 관한 해석 기법의 연구
정택우(T. W. Jung),이영선(Y. S. Lee),김대용(D. Kim),문영훈(M. Y. Hoon) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10
The Clad sheet is made roll-bonding process of the or more material with the different property. Good formability is an essential property in order to deform a clad metal sheet to a part or component. In this study, the mechanical properties and formability of a Mg-Al-SUS clad sheet are investigated. The clad sheet was deformed at elevated temperatures because of its poor formability at room temperature. Tensile tests of the each material and clad sheet were performed at various temperatures and at various strain rates. The limited draw ration (LDR) was obtained using a deep drawing test to measure the formability of the clad sheet. A finite element (FE) analysis was performed to predict formability of the cup drawing product, one_layer model and three_layer model.
남중희(J. H. Nam),정성환(S. H. Jung),정택우(T. W. Jung),이영선(Y. S. Lee) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
Gear is used for various purpose and one component of a wide range machines, many researchers have been done to study manufacture method using cold forging technology(by Cold forging and Extrusion) due to high productivity and material utilization. But forging technology of helical gear is very difficult because of helix angle, tool life and deformation control of material. So this work was focused method to forge without rotation of die-set. Multi-stage forming process to produce helical gear was designed total 4 processes that 1-3 processes are hot forging and 4 process is cold forming process. Tooth shape forming process of helical gear investigated that forming method by bottom pressurization was optimum process in the results using finite element simulations. It was found that simulation results to predict forming load were slightly different from experiment results, but material flow and burr generation were in good agreement with experiment results.
A Study to improve dimensional accuracy of forged gear
Y. S. Lee(이영선),T. W. Jung(정택우),J. H. Lee(이정환),J. R. Cho(조종래),Y. H. Moon(문영훈) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
The dimension of forged part is different from that of die. Therefore, a more precise die dimension is necessarys to produce the precise part, considering the dimensional changes form forging die to final part. In this paper, both experimental and FEM analysis are performed to investigate the effect of several features including die dimension at each forging step and heat-treatment on final part accuracy in the closed-die upsetting. The dimension of forged part is checked at each stage as machined die, clod forged, and post-heat-treatment steps. The elastic characteristics and thermal influences on forging stage are analyzed numerically by the DEFORM-2D<SUP>TM</SUP>. The effect of residual stress after heat-treatment on forged part could be considered successfully by using DEFORM-HT<SUP>TM</SUP>.
Mg-Al-SUS 클래드 판재의 온간 드로잉성에 대한 해석 기법과 실험적 연구
황범규(B. K. Hwang),이영선(Y. S. Lee),정택우(T. W. Jung),김대용(D. Kim),문영훈(Y. H. Moon) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.10
The Clad sheet is made roll-bonding process of the one or more material with the different property. Good formability is an essential property in order to deform a clad metal sheet to a part or component. In this study, the mechanical properties and formability of a Mg-Al-SUS clad sheet are investigated. The clad sheet was deformed at elevated temperatures because of its poor formability at room temperature. Tensile tests of the each material and clad sheet were performed at various temperatures and at various strain rates. The limited draw ration (LOR) was obtained using a deep drawing test to measure the formability of the clad sheet. A finite element (FE) analysis was performed to predict formability of the cup drawing product, one_layer model and three_layer model.