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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Transactions of Materials Processing
Journal Basic Information
Journal DOI :
The Korean Society for Technology of Plasticity
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Volume & Issues
Volume 21, Issue 8 - Dec 2012
Volume 21, Issue 7 - Nov 2012
Volume 21, Issue 6 - Oct 2012
Volume 21, Issue 5 - Aug 2012
Volume 21, Issue 4 - Jul 2012
Volume 21, Issue 3 - Jun 2012
Volume 21, Issue 2 - Apr 2012
Volume 21, Issue 1 - Feb 2012
Selecting the target year
A Shaving Shear-Welding Process for Overlapped Aluminum Plates
Shang, L. ; Kim, T.H. ; Jin, I.T. ;
Transactions of Materials Processing, volume 21, issue 8, 2012, Pages 467~472
DOI : 10.5228/KSTP.2012.21.8.467
Shaving shear-welding is a solid-state welding process, which utilizes plastic deformation of surplus material. The solid-state nature of this process contributes to high integrity and strength of the weld. The objective of this study was to investigate the effects of process variables on the material flow patterns and identify the process condition for obtaining the best weld. FEM simulations were carried out along with experimental characterizations. The results showed the importance of the cutter angles and the overlap lengths, and helped attain the optimum shaving shear-welding die and the best process condition.
Development of a Torsion Joint Yoke for Motor-Driven Power Steering System Using a Double-Action Extrusion Process
Kim, H.M. ; Kim, Y.K. ; Park, Y.B. ;
Transactions of Materials Processing, volume 21, issue 8, 2012, Pages 473~478
DOI : 10.5228/KSTP.2012.21.8.473
The yoke, a component of conventional motor-driven power steering system, often contains welding defects from its manufacturing process. To eliminate these defects, the precision cold forging process has been tried. In this study, the double-action complex forging has been used to manufacture a torsion joint yoke. The backward extrusion proved faster than the forward extrusion in forging of the product. The double-action complex forging process utilized an upper die composed of a punch, a punch guide, a disc spring and a coil spring. The forged material pushes up the punch guide, and then the disc spring and the coil spring balances the backward extrusion force. Consequently, the flow of material was essentially in the forward direction, resulting in a successful forging operation. The forging load of Al 6061-T6 was higher than that of the automotive structural hot rolled plate.
Compensation for Elastic Recovery in a Flexible Forming Process Using Predictive Models for Shape Error
Seo, Y.H. ; Kang, B.S. ; Kim, J. ;
Transactions of Materials Processing, volume 21, issue 8, 2012, Pages 479~484
DOI : 10.5228/KSTP.2012.21.8.479
The objective of this study is to compensate the elastic recovery in the flexible forming process using the predictive models. The target shape was limited to two-dimensional shape having only one curvature radius in the longitudinal-direction. In order to predict the shape error the regression and neural network models were established based on the finite element (FE) simulations. A series of simulations were conducted considering input variables such as the elastic pad thickness, the thickness of plate, and the objective curvature radius. Then, at sampling points in the longitudinal-direction, the shape errors between formed and objective shapes could be calculated from the FE simulations as an output variable. These shape errors were expressed to a representative error value by the root mean square error (RMSE). To obtain the correct objective shape the die shape was adjusted by the closed-loop using the neural network model since the neural network model shows a higher capability of estimating the shape error than the regression model. Finally the experimental result shows that the formed shape almost agreed with the objective shape.
A Study on the Process Optimization by a Beadless Stamping
Kim, S.H. ; Shim, H.B. ;
Transactions of Materials Processing, volume 21, issue 8, 2012, Pages 485~492
DOI : 10.5228/KSTP.2012.21.8.485
As the shape of stamped part is complicated and as the trend toward light weight continues, the higher level of difficulty is required in making stamping die because of inevitably poor formability. The poor formability can be improved if the material flow during the stamping is carefully controlled. Application of drawbead became commonsense used to retard metal flow of blank into the die cavity at the region where wrinkle is expected. In the study, the concept of beadless stamping process is proposed and the method how to realize the beadless stamping process is presented. The validity of the proposed method is confirmed by the application of the real auto part.
Development of Cold Forging Process of Hollow-type Wheel Nut Wrench for Commercial Vehicles
Kim, H.S. ; Youn, J.W. ;
Transactions of Materials Processing, volume 21, issue 8, 2012, Pages 493~498
DOI : 10.5228/KSTP.2012.21.8.493
A wheel nut wrench is one of the hand tools used to loosen and tighten lug nuts on automobile wheels and it has generally a solid-type geometry for commercial vehicles. However, the solid-type wheel nut wrenches manufactured by hot forging processes exhibit several drawbacks such as heavy weight and rough surface finish. Thus, many efforts have been devoted to change the part geometry and improve the manufacturing process. For this purpose, the weight of the final product can be reduced drastically using a hollow tube as the initial stock, which can be manufactured by the more economical manufacturing process of cold forging. In this study, the cold forging of a hollow-type wheel nut wrench for commercial vehicles was designed based on the results of fundamental experiments and CAE analyses using the commercial finite element code DEFORM-3D. In addition, cold forging experiments were conducted on a special-purpose forming machine for hollow wheel nut wrenches in order to validate the designed process sequence. As results, it was found that the final products with a weight reduction of 39% and better surface appearance can be manufactured without any defect with the newly designed cold forging process.
Experimental and Numerical Analyses of Flexible Forming Process for Micro Channel Arrays of Fuel Cell Bipolar Plates
Kim, H.S. ; Shim, J.M. ;
Transactions of Materials Processing, volume 21, issue 8, 2012, Pages 499~505
DOI : 10.5228/KSTP.2012.21.8.499
The fuel cell is a very promising power generation system combining the benefits of extremely low emissions, high efficiency, ease of maintenance and durability. In order to promote the commercialization of fuel cells, a flexible forming process, in which a hyper-elastic rubber is adopted as a medium to transmit forming pressure, is suggested as an efficient and cost effective manufacturing method for fuel cell bipolar plates. In this study, the ability of this flexible forming process to produce the micro channel arrays on metallic bipolar plates was first demonstrated experimentally. Then, a finite element (FE) model was built and validated through comparisons between simulated and experimental results. The effects of key process parameters on the forming performance such as applied load and punch velocity were investigated. As a result, appropriate process parameter values allowing high dimensional accuracy without failure were suggested.
Microstructures of Bonding Interfaces after Semi-Solid Brazing of Aluminum Using A357 as a Filler Metal
Lee, S.Y. ;
Transactions of Materials Processing, volume 21, issue 8, 2012, Pages 506~511
DOI : 10.5228/KSTP.2012.21.8.506
Aluminum brazing normally requires a careful control of temperature due to the small interval between brazing and melting temperatures for base materials. Unsuitable processing conditions, including brazing temperature outside admissible range, gap between brazed materials or inadequate flux feeding, can lead to joining defects. In this study, A357 was used as a filler metal for the brazing of pure aluminum base materials and brazed at temperatures in the semi-solid state. Interface microstructures with base materials were observed using optical metallography(OM) and scanning electron microcopy(SEM) with energy dispersive spectroscopy(EDS), and compared to conventional aluminum brazing.