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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Transactions of Materials Processing
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Journal DOI :
The Korean Society for Technology of Plasticity
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Volume & Issues
Volume 24, Issue 6 - Dec 2015
Volume 24, Issue 5 - Oct 2015
Volume 24, Issue 4 - Aug 2015
Volume 24, Issue 3 - Jun 2015
Volume 24, Issue 2 - Apr 2015
Volume 24, Issue 1 - Feb 2015
Selecting the target year
Development of a Process to Simultaneously Weld and Extrude Pipe Using a Spring Type Wire Material
Ku, K.M. ; Kim, T.H. ; Jin, I.T. ;
Transactions of Materials Processing, volume 24, issue 5, 2015, Pages 317~322
DOI : 10.5228/KSTP.24.5.317
A process for the concurrent welding and extruding of pipe was designed for continuous production of fin tubes. Unlike a conventional pipe extrusion, the new process is able to extrude a pipe continuously without limit of length by using spring type wire material. The current paper provides the basic research for welding during the extrusion using a spring type wire material. The object of the current study is to investigate the possibility that the spring type wire material could be extrude into a welded pipe. The appropriate extrusion ratio was selected through investigation of loads using computer simulations. As a result, experiments showed that pipe could be welded and simultaneously extruded with spring type wire material of aluminum. The tensile strength of the welded and extruded aluminum pipe can reach 80% of tensile strength of original aluminum feedstock.
Effect of Process Parameters on Rectangular Cup Impact Extrusion of an AA1070 Aluminum Alloy
Jo, M.K. ; An, E. ; Park, I.W. ; Song, I.S. ; Kim, H. Y. ; Kim, D. ; Moon, Y.H. ; Kim, J.H. ;
Transactions of Materials Processing, volume 24, issue 5, 2015, Pages 323~331
DOI : 10.5228/KSTP.24.5.323
Impact extrusion is an economical and productive process that can replace the multistage deep drawing process for producing deep rectangular cases. In the current work, a three-dimensional finite element analysis of the impact extrusion process of a commercial purity aluminum alloy (AA1070) was performed to predict loads, material flow, and deformed shapes using the Hansel-Spittel rheology law, which describes the flow stress at various temperatures and strain rates. The role of various process parameters such as friction, clearance between punch and die, aspect ratio and thickness of billet on the process and the shapes was analyzed.
Optimal Design of the Punch Shape for a Housing Lower
Park, S.J. ; Park, M.C. ; Kim, D.H. ;
Transactions of Materials Processing, volume 24, issue 5, 2015, Pages 332~339
DOI : 10.5228/KSTP.24.5.332
In the current paper, a cold forging sequence was developed to manufacture a precisely cold forged H/Lower, which is used as the air back unit in commercial automobiles. The preform shape of the H/Lower influences the dimensional accuracy and stiffness of the final product. The shape factor (SF) ratio and shape of the tools are considered as the design parameters to achieve adequate backward extrusion height and maintain appropriate thickness variations. The optimal conditions of the design parameters were determined by using an artificial neural network (ANN). To experimentally verify the optimal preform and tool shapes, the experiments of the backward extrusion of the H/Lower were executed. The process design methodology proposed in the current paper, can provide a more systematic and economically feasible means for designing the preform and tool shapes for cold forging.
Die Design for Shape Drawing to Improve the Dimensional Accuracy of a Hollow LM-Guide Rail
Park, J.H. ; Lee, K.H. ; Kim, S.M. ; Kim, H.J. ; Kim, S.J. ; Kim, B.M. ;
Transactions of Materials Processing, volume 24, issue 5, 2015, Pages 340~347
DOI : 10.5228/KSTP.24.5.340
Multi-pass shape drawing is used to manufacture long products of arbitrary cross-sectional shapes. This process allows smooth surface finishes and closely controlled dimensions of the cross-sectional shape. Tube shape drawing for hollow type products provides material savings and weight reduction. The intermediate die shapes are very important in multi-pass tube shape drawing. In the current paper, the design method for the intermediate dies in a tube shape drawing process is developed using a die offset for corner filling (DOCF) method. Underfill defects are related to the radial velocity distribution of each divided section in the deformation zone. The developed intermediate die shape design was applied to the two-pass tube shape drawing with fixed mandrel for manufacturing a hollow linear motion (LM) guide rail. The proposed design method led to uniform and steady metal flow at each divided section. FE-simulations and experiments were conducted to validate the effectiveness of the proposed method in multi-pass tube shape drawing process.
The Improvement of Formability using the Polar-coordinate FLD with Strain Path Independence
Bae, M.K. ; Hong, S.H. ; Choi, K.Y. ; Yoon, J.W. ; Kim, Y.S. ;
Transactions of Materials Processing, volume 24, issue 5, 2015, Pages 348~353
DOI : 10.5228/KSTP.24.5.348
The PEPS(Polar-coordinated Effective Plastic Strain) FLD(Forming Limit Diagram), a new type of FLD based on a polar representation of the EPS(Effective Plastic Strain), appears to be an effective solution to the problem of non-linear strain path effects. This method has the advantages of the familiar strain-based diagram for linear loading, but without the strain-hardening limitations of the stress-based diagram, or non-intuitive aspects of alternate Cartesian diagrams based on effective plastic strain. In the current study, the PEPS FLD was applied to the development process of an aluminum automobile-body panel, including the necking or crack prediction, die design, and die modification. As a result, the PEPS FLD provided improved formability of aluminum sheet as compared to deriving the potential formability with non-linearity.
Local Softening of Hot-stamped Parts using a Laser Heat Treatment
Kim, K.B. ; Jung, Y.I. ; Kim, T.J. ;
Transactions of Materials Processing, volume 24, issue 5, 2015, Pages 354~360
DOI : 10.5228/KSTP.24.5.354
AHSS (Advanced High Strength Steels) has been increasingly employed by global automotive OEMs in order to satisfy strengthened regulations and reduce weight for fuel efficiency. Hot stamping using boron steels in AHSS increases not only formability but also strength. The typical hot-stamped automotive part is the center pillar that is critical for vehicle side impact. However, the hot-stamped part can be risky for the passenger safety caused by brittle fracture under a vehicle collision. The high power diode laser is suitable for the heat treatment giving AHSS increased elongation that prevents brittle fracture in car crash. Therefore, local softening by laser heat treatment for energy absorption area on the hot-stamped part improves crash-worthiness.
Determination of the Forming Limit Strain of Sheet Metals by the Time-dependent Method
Kim, S.G. ; Oh, T.H. ; Kim, J.D. ; Kim, H.J. ;
Transactions of Materials Processing, volume 24, issue 5, 2015, Pages 361~367
DOI : 10.5228/KSTP.24.5.361
The forming limit diagram (FLD) is the most commonly used tool for evaluating of sheet metal formability in the manufacturing field as well as the finite element analysis (FEA)-based design process. Determination of the forming limits is considerably influenced by testing/measuring machines, techniques and conditions. These influences may cause a large scatter in FLD from laboratory to laboratory. Scatter is especially true when the ‘position-dependent method’, as is specified in most national and international standards, is used. In the current study a new ‘time-dependent method’ is proposed, which is to determine the forming limit strains more accurately and reasonably when producing a FLD from experimental data. This method is based on continual strain measurement during the test. The results are compared to those from the existing standardized methods.
Hydroforming of a Non-axisymmetric Thin-walled Tubular Component with Variable Cross Sections
Kang, H.S. ; Joo, B.D. ; Hwang, T.W. ; Moon, Y.H. ;
Transactions of Materials Processing, volume 24, issue 5, 2015, Pages 368~374
DOI : 10.5228/KSTP.24.5.368
Hydroforming of a non-axisymmetric thin-walled tubular component with variable cross sections was analyzed. In order to solve the sealing problem which occurred due to the thin and non-axisymmetric shape, the use of a lead patch on the punch, which had been successful in hydroforming of thin tubes, was evaluated. A lead patch was attached to the punch to solve the sealing problem, which was caused by the stress gradient in the non-axisymmetric shape. FEM and experiments were also performed to analyze these sealing problems associated with the punch shape and non-axisymmetric shape. Finally, the lead patch was attached at tube surface where intensive local strain concentration would occur to enhance the hydroformability. These methods were successfully used to fabricate non-axisymmetric thin-walled tubular component with variable cross sections that had previously failed during traditional hydroforming.