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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of Materials Processing
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Journal DOI :
The Korean Society for Technology of Plasticity
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Volume & Issues
Volume 16, Issue 8 - Dec 2007
Volume 16, Issue 7 - Nov 2007
Volume 16, Issue 6 - Oct 2007
Volume 16, Issue 5 - Aug 2007
Volume 16, Issue 4 - Jul 2007
Volume 16, Issue 3 - Jun 2007
Volume 16, Issue 2 - Apr 2007
Volume 16, Issue 1 - Feb 2007
Selecting the target year
Study of Deflection around Hydropierced Hole with Experiment
Han, S.S. ; Kang, Y.S. ; Kim, G.H. ;
Transactions of Materials Processing, volume 16, issue 3, 2007, Pages 157~162
DOI : 10.5228/KSPP.2007.16.3.157
The hydropiercing process gives a lot of advantages to the tube hydroforming such as cost reduction and high productivity. However it has a drawback, the amount of deflection around the hole is bigger than that of conventional die piercing process. The deflection can cause the problem at the assembly process of stamped parts and hydroformed part. Therefore the reduction of deflection is one of the most important issues for hydropiercing process. In this study, the deflection around hydropierced hole was investigated by experiment. As a result of investigation, the amount of deflection is influenced by the internal pressure, the material thickness' and the size of hole. Especially the hole size is most influencing factor on the deflection around the hydropierced hole.
Development of Automatic Drawing Program for Hemming Unit by AutoCAD
Kim, D.S. ; Song, Y.J. ; Chung, H. ; Kim, Y.B. ; Hahn, Y.H. ;
Transactions of Materials Processing, volume 16, issue 3, 2007, Pages 163~171
DOI : 10.5228/KSPP.2007.16.3.163
Due to the complicated character of the hemming process for automobile panels, it is very difficult to setup a consistent and reliable die design guide rule that require subtle decision of experienced experts and multiple trials during hemming die design and making. In this paper an automatic die design system of hemming units is pursued by presenting some algorithms, in which geometric data and constraints of the hemming units were converted to formula. The geometries and kinematics of all part for two kinds of hemming units, 2-link type and 4-link type were analysed kinematically to build the design algorithm. The algorithms were verified by automatic drawing used AutoCAD VBA program in example for the hemming unit design of a bonnet.
Process Design for Large-Scale Ring-Rolling of Ti-6Al-4V Alloy
Yeom, J.T. ; Kim, J.H. ; Lee, D.G. ; Park, N.K. ; Choi, S.S. ; Lee, C.S. ;
Transactions of Materials Processing, volume 16, issue 3, 2007, Pages 172~177
DOI : 10.5228/KSPP.2007.16.3.172
The process design for large-scale ring rolling of Ti-6Al-4V alloy was performed by calculation method, processing map approach and FEM simulation. The ring rolling design includes geometry design and optimization of process variables. The calculation method was used to make geometry design such as initial billet and blank sizes, and final rolled ring shape. A commercial FEM code, SHAPE-RR was used to simulate the effect of process variables in ring rolling on the distribution of the internal state variables such as strain, strain rate and temperature. In order to predict the forming defects during ring rolling and the formation of over-heating above
-transus temperature due to deformation heating, the process-map approach based on Ziegler's instability criterion was used with FEM simulation. Finally, an optimum process design to obtain sound Ti-6Al-4V rings without forming defects was suggested through combined approach of Ziegler's instability map and FEM simulation results.
The Effect of Pressure on Liquid Segregation in Direct Rheo-Forging Process of Aluminum Alloys
Oh, S.W. ; Bae, J.W. ; Kang, C.G. ;
Transactions of Materials Processing, volume 16, issue 3, 2007, Pages 178~186
DOI : 10.5228/KSPP.2007.16.3.178
Rheo-forging process of aluminum alloy is suitable for large parts of net shape without defects and excellent mechanical properties in comparison with conventional die casting and forging process. To control the microstructure of the product with high mechanical properties in rheo-forming, solid fraction is required to prevent porosity and liquid segregation. Therefore, in rheo-forging process, die shape, pressure type and solid fraction are very important parameters. The defects such as porosity, liquid segregation and unfitting phenomena occur during rheo-forging process. To prevent these defects, mechanical properties and microstructure analysis of samples versus the change of pressure are carried out and the problem and its solutions are proposed. Also, the mechanical properties versus various pressures were compared with and without heat treatment. The alloys used for rheo-forming are A356 and 2024 aluminum alloy. The rheology material is fabricated by electromagnetic process with controlling current and stirring time.
Computer Simulation of Complex Hot Forging Processes by a Forging Simulator Based on Finite Volume Method
Kim, B.T. ; Eom, J.G. ; Choi, I.S. ; Lee, M.C. ; Park, S.Y. ; Joun, M.S. ;
Transactions of Materials Processing, volume 16, issue 3, 2007, Pages 187~192
DOI : 10.5228/KSPP.2007.16.3.187
The finite volume method for forging simulation is examined to reveal its possibility as well as its problem in this paper. For this study, the finite volume method based MSC/SuperForge and the finite element method based AFDEX are employed. The simulated results of the homogeneous compression obtained by the two softwares are compared to indicate the problems of the finite volume method while several application examples are given to show the possibility of the finite volume method fur simulation of complex hot forging processes. It is shown that the finite volume method can not predict the exact solution of the homogeneous compression especially in terms of forming load and deformed shape but that it is helpful to simulate very complex forging processes which can hardly be simulated by the conventional finite element method.
Thermally-Induced Birefringence in Freely Quenched Plates of Polycarbonate
Lee, H.S. ; Isayev, A.I. ;
Transactions of Materials Processing, volume 16, issue 3, 2007, Pages 193~200
DOI : 10.5228/KSPP.2007.16.3.193
Simulations of the thermally-induced residual stresses and birefringence in freely quenched plates of polycarbonate were performed by using the linear viscoelastic and photoviscoelastic constitutive equations for the mechanical and optical properties, respectively, and the first order rate equation for volume relaxation. The predictions for the birefringence showed good agreement with experimental measurements. However, for initial temperature close to the glass transition temperature, some differences existed around the surface layer. Based on the simulation, the influences of various cooling conditions on the residual stress and birefringence in plates were investigated. The residual stress and birefringence increased with increasing initial temperature, decreasing coolant temperature and increasing heat transfer coefficient of coolants.
Tube Hydroforming Process Design of Torsion Beam type Rear Suspension Considering Durability
Lim, H.T. ; Oh, I.S. ; Ko, J.M. ; Kim, H.Y. ;
Transactions of Materials Processing, volume 16, issue 3, 2007, Pages 201~209
DOI : 10.5228/KSPP.2007.16.3.201
Generally, the forming process of suspension system parts have been considered only considered with the formability and have not been considered with the durability of suspension system. But the durability of suspension system is very important characteristic for the dynamic performance of vehicle. Therefore, the suspension system should be manufactured to consider the durability as well as the formability. This paper is about an optimum forming process design with the effect of section properties to consider the roll durability of torsion beam type suspension. In order to determine the tube hydroforming process for the satisfaction the roll durability, the stamping and hydroforming simulation by finite element method were performed. And the results from finite element analysis and roll durability examination showed the tube hydroforming process of torsion beam is optimized as satisfying the durability performance.
In-Situ Measurement of Densification Behavior of Nano Cu Powders during Sintering
Yoon, S.C. ; Bok, C.H. ; Kwak, E.J. ; Rhee, C.K. ; Kim, H.S. ;
Transactions of Materials Processing, volume 16, issue 3, 2007, Pages 210~214
DOI : 10.5228/KSPP.2007.16.3.210
Manufacturing bulk nanostructured materials with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy via compaction and sintering. In the study, densification behavior of nano Cu powders during pressureless sintering was investigated using an in-situ optical dilatometer technique. The initial heating and steady temperature stages during the sintering of nano Cu powder compacts were observed. At the initial heating stage, the powder compact has many porosities and full densification needs high temperature and/or high pressure sintering. In the experimental analysis, changes in geometry and density were measured and discussed for optimal consolidation and densification by the in-situ optical dilatometer.