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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 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
Evaluation of Friction Characteristics for High-Strength-Steel Sheets Depending on Conditions
Kim, J. E. ; Heo, J. Y. ; Yoon, I. C. ; Song, J. S. ; Youn, K. T. ; Park, C. D. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 381~386
DOI : 10.5228/KSTP.24.6.381
Recently, high-strength-steel sheets have been used extensively for increasing fuel-efficiency and stability in automobiles. A study on the characteristics regarding friction factors is required because high-strength-steel sheets have higher contact pressure at the tool interface as compared to low-strength steel sheets. For the current study, a sheet friction test was used to examine the influence of several factors on friction. The friction tests were performed on two types of sheet steels (SPFC590 and SPFC980) to obtain friction coefficients as a function of contact pressure, surface roughness, lubricant viscosity, and speed. Based on the experimental results for SPFC590 and SPFC980, the friction coefficient decreased with increasing contact pressure, but the friction coefficient increased with increasing surface roughness. Also, the friction coefficient decreased with increasing lubricant viscosity and decreasing speed.
Static FE Analysis of Air Springs for Passenger Cars Considering the Mounting Steps
Lee, H. W. ; Hahn, H. T. ; Park, J. Y. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 387~394
DOI : 10.5228/KSTP.24.6.387
Air springs are designed to support loads using the volume elasticity in a cylindrical shaped air bag made of a composite material with a rubber matrix and two plies of reinforced fibers. Recently, applications of these springs have been expanded from railway vehicles to passenger cars. The current study presents a finite element analysis of a manufactured air spring for a passenger car. The analysis was conducted including the mounting steps of the air bag using a static loading condition. A method for controlling the internal pressure and displacements during the mounting step was developed. The characteristic load curve and the shape of the air bag were in good agreement with the experimental data with respect to the design height, the bump height and the rebound height. Results indicate that ply angles of fibers vary from 38 degrees to 56 degrees during static loading.
Prediction of the Plastic Strain Ratio Evolution of a Dual-phase Steel
Ha, J. ; Lee, J.W. ; Lee, M. G. ; Barlat, F. ; Kim, J. H. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 395~399
DOI : 10.5228/KSTP.24.6.395
A microstructure-based finite element simulation was conducted to predict the plastic strain ratio (R-value) of a dual-phase (DP) steel. The representative volume elements (RVEs) concept was adopted for the image-based FE modeling and a 3D model was constructed using sequential 2D images. Each phase was considered with the von-Mises yield criterion and the Swift model. The Swift parameters were defined by the empirical equations based on the chemical composition. The developed model was applied to analyze the effect of residual stress on the R-value and stress distribution. In order to consider the residual stress development after cold rolling, 10 % compression was applied in the thickness direction and unloaded before the tensile stress was applied in the rolling direction. The results showed a reasonable prediction for the R-value evolution: a sharp increase at small strains was well described and a transition followed in the downward direction. The R-value evolution was analyzed using the stress distribution change on the π-plane
Design of Strip Bridge for Unsymmetrical Progressive Stamping for an Automotive Seat Side Cushion Pane
Hong, S. ; Joung, C. S. ; Choi, B. S. ; Lee, D. Y. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 400~404
DOI : 10.5228/KSTP.24.6.400
For mass production of stamped parts, which require complicated in-press operations, it is always advisable to use a progressive die set. It is difficult to choose a progressive die set if the stamped parts need to be deep drawn and especially if they are unsymmetrical. Because unsymmetrical deep drawing parts are very sensitive to the effect of weight during moving to the next step, they are hard to exactly locate on the die face. An automotive seat side cushion panel is about 80mm high, unsymmetrical and its low edge needs hemming, so it is hard to produce even using a progressive die set. In the current paper a progressive stamping for seat side cushion panel was examined. Five strip bridges were considered to be strong enough to move to the next die as predicted by the CAE analysis.
Friction Behavior of DLC Coating Slid Against AZ31 Magnesium Alloy at Various Temperatures
Gwon, H. ; Kim, M. G. ; Hur, H. L. ; Kim, Y.-S. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 405~410
DOI : 10.5228/KSTP.24.6.405
Sheet-forming of Mg alloys is conducted at elevated temperatures (250℃) due to the low formability at room temperature. The high-temperature process often gives rise to surface damage on the alloy (i.e. galling.) In the current study, the frictional characteristics of DLC coating slid against an AZ31 Mg alloy at various temperatures were investigated. The coating has been used widely for low-friction processes. Dry-sliding friction and galling characteristics of an AZ31 Mg alloy (disk), which slid against uncoated and a DLC-coated STD-61 steel (pin), were investigated using a reciprocating-sliding tribometer at room temperature and 250℃. To represent the real sliding phenomena during a sheet metal forming process, single-stroke tests were used (10mm stroke length) rather than a reciprocating long sliding-distance test. The DLC coating suppressed adhesion between the alloy and the tool steel at room temperature, and exhibited a low friction coefficient. However, during sliding at 250℃, severe adhesion occurred between the two surfaces, which resulted in a high friction coefficient and galling.
Hot Forging of an Engine Piston using Control Cooling
Lee, S. I. ; Choi, D. H. ; Lee, J. H. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 411~417
DOI : 10.5228/KSTP.24.6.411
The piston engine is an essential component in automobiles. Since the piston is used in a high temperature and high pressure environment, the piston needs to be manufactured to achieve high strength and high durability. In addition, cost reduction is also an important consideration. In conventional forging, an additional heat treatment after hot forging is necessary to ensure proper mechanical properties for heavy-duty engine pistons. The newly developed manufacturing method lowers production costs by saving manufacturing time and reduces energy consumption. The current paper describes the hot forging of an engine piston made from 38MnSiVS5 micro-alloyed steel using controlled cooling. The finite element analysis was used to check for possible problems and suitable press capacity. Hot forging experiments were then conducted on a 2500tons crank press to evaluate feasibility of the proposed material and process. To check the mechanical properties after hot forging, the forged specimens were tensile tested, and the microstructures were examined in order to compare the results with the conventionally forged material. The skirt region of the as-forged 38MnSiVS5 piston showed better material properties compared to the conventional material. In addition, the total production time was reduced by about 80% as compared to conventional forging.
Development of Thermoplastic-Thermoset Multi Component Injection Mold for a Waterproof Connector
Jung, T. S. ; Choi, K. S. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 418~425
DOI : 10.5228/KSTP.24.6.418
Based on eco-friendly advantages and the enhanced development in the chemical and physical characteristics, liquid silicone rubber (LSR) is widely used in producing precision parts in the automotive, medical, electronics, aeronautical and many other industries. In the current work, a thermoplastic-thermoset multi component injection molding (MCM) was developed for a waterproof automotive connector housing using PBT and LSR resins. Measurements of the rheological characteristics of PBT and LSR were made to improve the reliability of the numerical analysis for the multi component injection process. With the measured viscosity, pvT and curing data, numerical analysis of the multi cycle injection molding was conducted using simulation software (Sigma V5.0).
Effects of Initial Slug Design on the Earring of a Rectangular Battery Case During Impact Extrusion
Lim, J. H. ; Choi, S. ; Chung, W. J. ; Shin, J. H. ; Lee, J. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 425~430
DOI : 10.5228/KSTP.24.6.425
In the current paper, the effects of initial slug design on the earring of an Al rectangular battery case manufactured by impact extrusion were studied. During impact extrusion, non-uniform metal flow between the long and the short sides of the battery case leads to earring, which is subsequently trimmed. Process parameters such as friction, aspect ratio of the battery case, the die shape and the forming temperature tend to induce earring because they cause greater non-uniform metal flow. Large aspect ratio of the battery case and high friction between slug and die can greatly affect the earring of a rectangular battery case. To make a rectangular battery case without earring, it is necessary to control metal flow uniformly during impact extrusion. One of the ways to reduce the earring is to control the metal flow of slug at the initial upsetting stage. To analyze the effects of the initial slug design on earring, FE analysis was conducted using DEFORM 3D. Two types of initial slug designs were evaluated where volume was removed along either the width or thickness directions. The results show that the initial slug design can be effective in adjusting the uniformity of metal flow.
Path Control of MR Fluid Jet Polishing System for the Polishing of an Aspherical Lens Mold Core
Kim, K. B. ; Cho, M. W. ; Ha, S. J. ; Cho, Y. K. ; Song, K. H. ; Yang, J. K. ; Cai, Y. ; Lee, J. W. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 431~436
DOI : 10.5228/KSTP.24.6.431
MR fluid can change viscosity in the presence of a magnetic field. A characteristic of MR fluid is reduced scattering during jetting. For these reasons a MR fluid jet polishing system can be used for ultra-precision polishing. In the current paper, the polishing path was calculated considering the aspherical lens profile equation and the experimental conditions for the MR fluid jet polishing system. Then the polishing of an aspherical lens mold core using the MR fluid jet polishing system with the calculated path control was made and the results were compared before and after polishing.
Aspherical Lens Design and Injection Mold Analysis Using Extracted Shape Information
Song, K. H. ; Kim, B. C. ; Yoon, H. S. ; Yang, J. K. ; Kim, K. B. ; Xiao, H. ; Cho, M. W. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 437~442
DOI : 10.5228/KSTP.24.6.437
The development of polishing technology has enabled the production of injection molds with high quality surfaces and shapes. For products such as mobile phones which require high quality performance the use of plastic materials has many constraints such as shrinkage and deflection. The purpose of the current research is to use reverse engineering in order to find and analyze the data of a selected aspherical lens and then creating a process to design an improved lens. Additionally, the improved lenses are subject to molding analysis. In order to solve this problem, the lens construction program, Zemax, was used to analyze and optimize performance. In the case of optimization, the object was to eliminate spherical aberration and to find good MTF data. The result of the optimization data was similar to the MTF data found from a random lens. Specific resin and analysis conditions were selected and CAD modeling was done to enhance the injection molding analysis.
Application Trend of Plastics: Manufacturing Technology of Plastics for Lightweight Automobile
Lyu, M.-Y. ; Choi, T. G. ; Cho, H. S. ;
Transactions of Materials Processing, volume 24, issue 6, 2015, Pages 443~450