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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Precision Engineering
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Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 32, Issue 12 - Dec 2015
Volume 32, Issue 11 - Nov 2015
Volume 32, Issue 10 - Oct 2015
Volume 32, Issue 9 - Sep 2015
Volume 32, Issue 8 - Aug 2015
Volume 32, Issue 7 - Jul 2015
Volume 32, Issue 6 - Jun 2015
Volume 32, Issue 5 - May 2015
Volume 32, Issue 4 - Apr 2015
Volume 32, Issue 3 - Mar 2015
Volume 32, Issue 2 - Feb 2015
Volume 32, Issue 1 - Jan 2015
Selecting the target year
Development of Manufacturing Process for Long-Neck Flange by Spinning
Gwak, Gi Yeol ; Cho, Jong Rae ; Choi, Jin Young ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 929~935
DOI : 10.7736/KSPE.2015.32.11.929
The long neck flange is used to connect piping arrangements where the lap joint is applied. Generally, the component can be manufactured by welding, but this method is both time and cost intensive. Embrittlement at the heat affected zones was also considered. A spinning method developed to improve the manufacturing process and solve the problems of welding. The flange area of the long neck flange can be formed by changing the direction of the metal flow, from axial to radial, while maintaining pressure by using an outer mold and a lap roller. A modified process was additionally developed using a round roller rather than the outer mold. In this modification, the round roller can form the shape of all sizes of long neck flange. Using these flexible methodologies, the cost to prepare outer molds and the time to install and remove the molds can be significantly reduced.
Prediction of Texture Evolution in Equal Channel Angular Extrusion (ECAE) Using Rate-Independent Crystal Plasticity with Rigid-Plastic Finite Element Method
Kim, Kyung-Jin ; Yoon, Jeong-Whan ; Yang, Dong-Yol ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 937~944
DOI : 10.7736/KSPE.2015.32.11.937
Recently, the change of mechanical properties and microstructural evolution during severe plastic deformation (SPD), such as Equal Channel Angular Extrusion (ECAE), has been the subject of intensive investigation because of the unique physical and mechanical properties of severely deformed materials. In this study, two types of ECAE processes were considered, dies with intersection angles
, using experiments and simulations. The decoupled method, in which the rigid-plastic finite element method is incorporated with the rate-independent crystal plasticity model, was applied to predict the texture evolution in commercially pure aluminum during the ECAE processes with
dies. The simulated textures were compared with a measured texture via an EBSD OIM analysis. The comparison showed that the simulated textures generally were in good agreement with the experimentally measured texture.
Improvement of Formability in Automobile Panels by Variable Blank Holding Force with Consideration of Nonlinear Deformation Path
Jeong, Hyun Gi ; Jang, Eun Hyuk ; Song, Youn Jun ; Chung, Wan Jin ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 945~952
DOI : 10.7736/KSPE.2015.32.11.945
In drawing sheet metal, the blank holding force is applied to prevent wrinkling of the product and to add a tensile stress to the material for the plastic deformation. Applying an inappropriate blank holding force can cause wrinkling or fracture. Therefore, it is important to determine the appropriate blank holding force. Recent developments of the servo cushion open up the possibility to reduce the possibility of fracture and wrinkling by controlling the blank holding force along the stroke. In this study, a method is presented to find the optimal variable blank holding force curve, which uses statistical analysis with consideration of the nonlinear deformation path. The optimal blank holding force curve was numerically and experimentally applied to door inner parts. Consequently, it was shown that the application of the variable blank holding force curve to door inner parts could effectively reduce the possibility of fracture and wrinkling.
Methodology of Three-Dimensional Thermoforming Analysis to Simulate Forming Process of Medium and Large-Sized Plastic Parts
Lee, Ho Jin ; Ahn, Dong Gyu ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 953~960
DOI : 10.7736/KSPE.2015.32.11.953
The thermoforming process has been widely used to manufacture medium- and large-sized plastic parts because of the relatively low cost and high productivity, as compared with other plastic forming processes. One of current salient issues of thermoforming industries is the reduction of trial and error during the production of the thermoformed product. Hence, there is a significant increasing interest in the thermoforming analysis by the thermoforming industries. The goal of this paper is to investigate a methodology of the three-dimensional thermoforming analysis for medium- and large-sized plastic parts. There is a discussion about methodologies of thermoforming analysis, as well as material modeling, and three-dimensional finite element analysis. Furthermore, there is an examination, through case studies, about the applicability of the proposed methodology concerning the thermoforming analysis.
Development of Injection Mold for Subminiature Lenses Using Shell Runners Containing Multiple Holes
Yoon, Seung Tak ; Park, Keun ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 961~968
DOI : 10.7736/KSPE.2015.32.11.961
This study aims to develop an efficient mold structure for the injection molding of a subminiature lens, using shell-type runners instead of traditional cylindrical runners. While the shell runner has the advantage of shorter cooling time due to its thinner geometry, this smaller thickness causes an increase in injection pressure. In this study, the design of the shell runner was modified to contain multiple holes for the purpose of reducing injection pressure. Numerical analyses were performed for shell runners of various hole-shapes, and the resulting filling and cooling characteristics were discussed; the rhombic hole showed the best result for both filling and cooling characteristics. Subsequently, injection molding experiments were performed using an injection mold fabricated based on the rhombic design. The lens parts were successfully molded with highly-reduced cycle time and without degradation of part quality.
Numerical Analysis of the Filling Stage in Insert Injection Molding of Microfluidic Chip with Metal Electrodes
Lee, Bong-Kee ; Na, Seung-Sik ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 969~976
DOI : 10.7736/KSPE.2015.32.11.969
In the present study, a numerical investigation of an insert injection molding process was carried out for the development of thermoplastic microfluidic chip plates with metal electrodes. Insert injection molding technology enables efficient realization of a plastic-metal hybrid structure and various efforts have been undertaken to produce novel components in several application fields. The microfluidic chip with metal inserts was proposed as a representative example and its molding process was analyzed. The important characteristics of the filling stage, such as the effects of filling time and thickness of the part cavity, were characterized. Furthermore, the detailed distributions of pressure and temperature at the end of the filling stage were investigated, revealing the significance of metal insert temperature.
Study on Cold Forward Extrusion Formality Analysis along with Tool Entrance Angle of Helical Gear for Electronic Parking Brake Using Finite Element Analysis
Kim, Byeong Kil ; Lee, Hyun Goo ; Cho, Jae Ung ; Jeong, Kwang Young ; Cheon, Seong Sik ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 977~982
DOI : 10.7736/KSPE.2015.32.11.977
This study uses finite element analysis to evaluate the forming load of tool entrance angle of the cold forward extrusion molding process of helical gear; this can replace the spur gear applied to the Electronic Parking Brake (EPB) system. A cold forging process is often used in the automobile industry as well as in various industrial machines due to its high efficiency. Finite element analysis is frequently used when interpreting results of the forging process. Formality was evaluated by calculating tooth profile filling rate of helical gear. Change in required forming load was investigated when the entrance angle of forward extrusion tool die was changed from
, also by finite element analysis. We suggest suitable tool entrance angles.
Improvement in Surface Roughness by Multi Point B Axis Control Method in Diamond Turning Machine
Kim, Young-Bok ; Hwang, Yeon ; An, Jung-Hwan ; Kim, Jeong-Ho ; Kim, Hye-Jeong ; Kim, Dong-Sik ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 983~988
DOI : 10.7736/KSPE.2015.32.11.983
This paper details a new ultra-precise turning method for increasing surface quality, "Multi Point B Axis Control Method." Machined surface error is minimized by the compensation machining process, but the process leaves residual chip marks and surface roughness. This phenomenon is unavoidable in the diamond turning process using existing machining methods. However, Multi Point B axis control uses a small angle (<
) for the unused diamond edge for generation of ultra-fine surfaces; no machining chipping occurs. It is achieved by compensated surface profiling via alignment of the tool radial center on the center of the B axis rotation table. Experimental results show that a diamond turned surface using the Multi Point B axis control method achieved P-V
and Ra 1.1nm and these ultra-fine surface qualities are reproducible.
Defect Detection in Laser Welding Using Multidimensional Discretization and Event-Codification
Baek, Su Jeong ; Oh, Rocku ; Kim, Duck Young ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 989~995
DOI : 10.7736/KSPE.2015.32.11.989
In the literature, various stochastic anomaly detection methods, such as limit checking and PCA-based approaches, have been applied to weld defect detection. However, it is still a challenge to identify meaningful defect patterns from very limited sensor signals of laser welding, characterized by intermittent, discontinuous, very short, and non-stationary random signals. In order to effectively analyze the physical characteristics of laser weld signals: plasma intensity, weld pool temperature, and back reflection, we first transform the raw data of laser weld signals into the form of event logs. This is done by multidimensional discretization and event-codification, after which the event logs are decoded to extract weld defect patterns by
Bayes classifier. The performance of the proposed method is examined in comparison with the commercial solution of PRECITEC's LWM
and the most recent PCA-based detection method. The results show higher performance of the proposed method in terms of sensitivity (1.00) and specificity (0.98).
Design Optimization of Valve Support with Enhanced Seismic Performance
Kim, Hyoung Eun ; Keum, Dong Yeop ; Kim, Dea Jin ; Kim, Jun Ho ; Hong, Seong Kyeong ; Choi, Won Mok ; Kim, Sang Yeong ; Seok, Chang Seong ;
Journal of the Korean Society for Precision Engineering, volume 32, issue 11, 2015, Pages 997~1005
DOI : 10.7736/KSPE.2015.32.11.997
In this study, modal analysis and equivalent static load analysis for valve supports of 26" gas piping in gas stations were conducted and the existing straight and inclined types of valve supports were compared using seismic performance testing. Also, a new valve support shape was suggested by optimizing position of fastener holes, width and thickness of the support, and size of bracket. Improvement in seismic performance by design optimization was verified through equivalent static load analysis. The seismic performance of the newly proposed valve support was greatly improved and the maximum displacement and maximum stress of the seismic load was about 20% lower than those of the existing valve support.