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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
Editor in Chief :
Volume & Issues
Volume 12, Issue 8 - Dec 2003
Volume 12, Issue 7 - Nov 2003
Volume 12, Issue 6 - Oct 2003
Volume 12, Issue 5 - Aug 2003
Volume 12, Issue 4 - Jul 2003
Volume 12, Issue 3 - Jun 2003
Volume 12, Issue 2 - Apr 2003
Volume 12, Issue 1 - Feb 2003
Selecting the target year
The Present and the Future for Dies and Molds Industry in Korea
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 421~432
DOI : 10.5228/KSPP.2003.12.5.421
The dies & molds are a very economical production tool and a high value-added product because of its mass production capability compared to other production methods. Due to the very stiff international competitiveness, the industries meet many obstacles. For the promotion of the industry, the status and the international trends of the industry are measured. The vision and strategy are driven. In Korea, large portion of dies and molds are still low value-added and make large number of tools. In order to advance this industry to the high-tech area and gain competitiveness in the global marketplaces, effective means of resource investment and strategy should be properly provided.
Die Design for Tube Hydroforming Process Considering Preforming Effect
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 433~439
DOI : 10.5228/KSPP.2003.12.5.433
Springback Characteristics of Tailor-Welded Strips in U-bending
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 440~448
DOI : 10.5228/KSPP.2003.12.5.440
Sheet or plate bending is one of the most important industrial metal forming processes. Considerable attention has been focused on gaining a better understanding of bending characteristics. One of defaults in bending process is the springback. In this study, the springback characteristics of tailor-welded strips in U-bending process was investigated. Furthermore, effect of the process variables such as the geometry of the tools, thickness combination of workpiece, and welding prcoessing on springback were experimentally clarified. First, tailor-welded strips are joined by the laser welding process and consisted of two types of thickness combinations of the SCPl sheet,
to investigate the effect of different thickness combination on the springback. Secondly, two different directionly welded strips, one was welded along the centerline of the strip-width and the other was along the centerline of strip-length, were adopted to compare the effects of the location of weld line on the springback. Some cases of the experimental results were compared to the results simulated by using a commercial FEM code, PAM-STAMP and the theoretical results using the springback formula as well.
A Process for the Control of Cell Size of 6061 Al foams by Multi-step Induction Heating Method
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 449~456
DOI : 10.5228/KSPP.2003.12.5.449
Multi-step induction heating process was applied to the powder compact melting technique as a new heating process to achieve pinpoint accuracy, faster cycle time, repeatability, non-contact and energy-efficient heat in a minimal amount of time. The objective of this study is the establishment of the input data diagram of multi step induction heating process for automation of the fabrication process of 6061 Al foams with desired density. At first, proper induction coil was designed to obtain a uniform temperature distribution over the entire cross sectional area of specimen. By using this coil, foaming experiments were performed to investigate the multi-step induction heating conditions such as capacity, temperature and time conditions of each heating and holding step. On the basis of the obtained multi-step induction heating conditions, relationship between final heating temperature and fraction of porosity was investigated.
Fabrication of Al 6061 Foamable Precursor by Powder Metallurgical and Induction Heating Method
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 457~464
DOI : 10.5228/KSPP.2003.12.5.457
In the powder compact melting technique, proper precursor fabrication is very important because density distribution after foaming and foamability are determined during precursor fabrication process. The fabrication of the precursor has to be performed very carefully because any residual porosity or other defects will lead to poor results in further processing. In order to evaluate the effect of the compaction parameters on the kinetics of the foaming process, a series of experiments were performed. In this study, aluminium foams with a closed cell structure were fabricated by using both the powder compact method and the induction heating process. A proper induction coil was designed to obtain a uniform temperature distribution over the entire cross sectional area of precursor. To establish the foamable precursor fabrication conditions, effects of process parameters such as the titanium hydride content (0.3∼1.5 wt.%), pressing pressure of the foamable precursor (50∼150kN) on the pore morphology were investigated.
Determination of a Multiattribute Utility Function Based on the Pairwise Comparison and the Application to Injection Molding Design
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 465~472
DOI : 10.5228/KSPP.2003.12.5.465
Engineering design can be viewed as a decision making process, which involves the nonlinear tradeoffs task among the multiple conflicting attributes and considers the robustness of design. In order to obtain best engineering design, methodology for accurate assessment of his/her preference about the multiple attributes is required. Conventionally, intuitive procedures based on lottery questions are used to elicit the designer's preference structure: however, they can lead to inconsistent and inexact preference results due to the rank reversal problems derived from the designer's big cognitive burden. In this paper, alternatively, a design methodology based on multiattribute utility function through the pairwise comparison among alternatives is presented. The proposed procedure is applied to an actual injection mold design with the aid of the CAE simulation and the result is discussed.
Development of Cold Forging Process for OP Shaft and Improvement of Forgeability of SNCM Steel
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 473~478
DOI : 10.5228/KSPP.2003.12.5.473
This study presents the enhancement of forgeability of SNCM522H materials. Target parts are output shaft(OP shaft) used as components of power train for automobiles. To carry out cold forging process of OP shaft by 1 pass instead of existing 2 pass process, studies in terms of process design and heat treatment were performed. To introduce the new process, the finite element method was accomplished, and to assess the validity of proposed heat treatment cycle, several experiments(hardness test, observation of optical microstructures, tensile test) were carried out. The 2Pass forging process could be reduced as lPass process through improvement of process and heat treatment technology and that would give cost reduction.
An Elastoplastic Analysis for Spent Nuclear Fuel Disposal Container and Its Bentonite Buffer: Asymmetric Rock Movement
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 479~486
DOI : 10.5228/KSPP.2003.12.5.479
This paper presents an elastoplastic analysis for spent nuclear fuel disposal container and its 50 cm thick bentonite buffer to predict the collapse of the container while the horizontal asymmetric sudden rock movement of 10 cm is applied on the composite structure. This sudden rock movement is anticipated by the earthquake etc. at a deep underground. Elastoplastic material model is adopted. Drucker-Prager yield criterion is used for the material yield prediction of the bentonite buffer and von-Mises yield criterion is used for the material yield prediction of the container. Analysis results show that even though very large deformations occur beyond the yield point in the bentonite buffer, the container structure still endures elastic small strains and stresses below the yield strength. Hence, the asymmetric 50 cm thick bentonite buffer can protect the container safely against the 10 cm sudden rock movement by earthquake etc.. Analysis results also show that bending deformations occur in the container structure due to the shear deformation of the bentonite buffer. The finite element analysis code, NISA, is used for the analysis.
Effect of Heat Treatment Process on the Shadow Mask Tension
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 487~492
DOI : 10.5228/KSPP.2003.12.5.487
Tension variations with heat treatment in shadow mask for flat braun tubes are investigated in this study. In CRT, landing shift of the electron beam due to thermal deformation of the tension mask made the color purity of screen worse. In order to get the final results of thermal deformation, the tensile force within the mask and the welding processes between the rail and the extended mask have to be analysed sequentially. In this study, the effect of heat treatment is studied in terms of tension variations of shadow mask during its manufacturing process.
Direct Observation of Crack Tip Stress Field Using the Mechanoluminescence of SrAl
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 493~497
DOI : 10.5228/KSPP.2003.12.5.493
The present investigation aims at visualizing the crack tip stress field using a mechanoluminescence material. The well known compound
was adopted as a mechanolurninescence material. Two more trivalent rare-earth elements such as Dy and Nd were taken into consideration as codopants to provide the appropriate trap levels. Samples of a variety of compositions were prepared by varing
doping contents, for which the combinatorial chemistry method was used. In order to search for the optimum composition for the highest mechanoluminescence, the luminescence induced by a compressive device including a CCD camera. In parallel, a compact tension specimen was prepared by mixing the luminescence powders of optimum composition and epoxy resin. Crack initiation from the mechanically machined sharp note tip and its growth during loading were found to be associated with the extent of light emission from
Study on Accuracy of Product by Radial Deformation of Die in Backward Extrusion
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 498~503
DOI : 10.5228/KSPP.2003.12.5.498
The die for cold forging gets a very high axial load and radial pressure during processing and hence deforms considerably in the radial direction. This radial deformation of die becomes a important factor influencing the dimensional accuracy of a product. In order to obtain the product with highly accurate dimension, therefore, it is essential to acquire some information on elastic deformation of the die and the product. The study has been performed for the relation of the deformation between the die and the product in backward extrusion. The strain of the die has been given by the simple experiment using the strain gauges attached to the outer surface of the die. Also the history of the deformation of the die and the product has been given by the experiment and Lames' formula. The results has been compared with the previous another method. The study has given useful results for the deformation history of the die and the product through the experiment and Lame's formula in backward extrusion, which can be applied in the die design for the product with accurate dimension.
A Study on the Evaluation of the Automatic Measurement Method of Plastic Strain Ratio by Two Extensometers
Transactions of Materials Processing, volume 12, issue 5, 2003, Pages 504~512
DOI : 10.5228/KSPP.2003.12.5.504
The plastic strain ratios(R-values) of low carbon steel sheets were determined by the automatic strain measurement method using two extensometers, the indirect photo method for the same tensile specimen during tensile test and the indirect method for the specimen after tensile test. The experimental results showed that the measured plastic strain ratios from the automatic strain measurement method using two extensometers coincided with those from the indirect photo method and the indirect method for all tensile specimens. In addition, the strain dependence of plastic strain ratios could be continuously recorded and the anisotropy of the strength coefficient, K, and strain hardening exponent, n, could be automatically calculated in three directions by computer through the use of two extensometers. The experimental results showed that the strain dependence of R-value was related to the anisotropy of strain hardening exponent in low carbon steel sheets.