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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 13, Issue 8 - Dec 2004
Volume 13, Issue 7 - Nov 2004
Volume 13, Issue 6 - Oct 2004
Volume 13, Issue 5 - Aug 2004
Volume 13, Issue 4 - Jul 2004
Volume 13, Issue 3 - Jun 2004
Volume 13, Issue 2 - Apr 2004
Volume 13, Issue 1 - Feb 2004
Selecting the target year
Asymmetric Rolling as Means of Texture and Ridging Control and Grain Refinement
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 559~563
DOI : 10.5228/KSPP.2004.13.7.559
Development of Low Annealing Treatment Omission Steel by New Rolling Process
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 564~569
DOI : 10.5228/KSPP.2004.13.7.564
A Study on Eulerian Analysis for the Steady State Rolling
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 570~579
DOI : 10.5228/KSPP.2004.13.7.570
The Filling Imbalance in Multi-Cavity Injection Molds with Unary Branch Type Runner Lay-out
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 580~585
DOI : 10.5228/KSPP.2004.13.7.580
Almost all injection molds have multi-cavity runner system fur productivity and are designed with geometrically balanced runner system in order to minimize filling imbalance between cavity to cavity during processing. However, filling imbalances have been observed though geometrically balanced runner lay-out. Generally, these filling imbalances are due to thermal unbalance, viscosity, characteristic of polymers and so on. These kinds of filling imbalances have already been reported by Beaumont since 1997, but his research has mainly focused on filling imbalance at binary runner. In this study, we conducted an experimental study about the filling imbalances in unary branch runner as well as binary branch runner and inquired into the causes of filling imbalances. The results could be summarized as fellowing: Filling imbalances existed in multi-cavity mold with unary branch runner, it could be decreased by optimizing processing condition such as increasing injection rate, and it is almost proportion to each polymer's temperature sensibility.
A Study on Cold Forging Process Design of a Terminal Pin for High-Voltage Capacitors
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 586~593
DOI : 10.5228/KSPP.2004.13.7.586
A terminal pin, which is a part of high-voltage capacitors, has a plate-shaped head section with thickness of 0.8mm. The current manufacturing process, in which the head section is welded on the body part, has given wide deviations of part qualities such as geometrical accuracy, mechanical strength and electrical stability. In this study, a cold forging process sequence was designed in order to produce the terminal pin as one piece. The plate-shaped head section requires an upsetting in the lateral direction of a cylindrical billet, which is followed by a blanking process. The deformed geometry of the lateral upsetting, however, could not be predicted precisely by intuition since metal flows of an axial and a lateral direction of the cylindrical billet would occur simultaneously. Therefore, in this study, three dimensional finite element analyses were applied to the lateral upsetting process in order to determine a proper diameter and height of the cylindrical billet. Once the geometry of the initial billet was determined, intermediate forging processes were designed by applying cold forging guidelines and the designed process sequence was verified by two dimensional finite element analysis. In addition, cold forging tryouts were conducted by using a die set, which was manufactured based on the designed process and finally we found that the part qualities were improved by the proposed cold forging process.
Study on the Compensation of Strain Measurement Error in Sheet Metals
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 594~599
DOI : 10.5228/KSPP.2004.13.7.594
In the sheet metal forming operations, the strain measurement of sheet panel is an essential work which provides the formability information needed in die design, process design, and product inspection. To measure efficiently complex geometry strains, the 3-dimensional automative strain measurement system, which theoretically has a high accuracy but practically has about 3～5％ strain error, is often used. For eliminating the strain error resulted in measuring the strains of formed panels using an automated strain measurement system, the position error calibration method is suggested, which computes accurate strains using the grids with accurate nodal coordinates. The accurate nodal coordinates are calculated by adding the nodal coordinates measured by the measurement system and the position error found using the multiple regression method as a function of the main error parameters obtained from the analysis of strain error in a standard cube. For the verification, the strain distributions of square and dome cups obtained from the position error calibration method are compared with those provided by the finite element analysis and ASAME.
A Study on Strain Rate Sensitivity by Unified Viscoplasticity
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 600~607
DOI : 10.5228/KSPP.2004.13.7.600
This paper addresses a viscoplastic constitutive model that allows a consistent way of modeling positive and negative rate sensitivities of flow stress concerned with dynamic strain aging. Based on the concept of continuum mechanics, a phenomenological constitutive model includes the use of a yield surface within the framework of unified viscoplasticity theory. To model negative rate sensitivity, rate-dependent back stress is introduced and flow stress in fully developed inelastic deformation regime is thus decomposed into the plastic contribution of rate independency and the viscous one of rate dependency.
Effect of Primary Si on Mechanical Properties in Hypereutectic Al-Si Alloy Produced by Gravity Die Casting
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 608~613
DOI : 10.5228/KSPP.2004.13.7.608
Mechanical properties of hypereutectic Al-Si alloy are influenced by the size and distribution of primary Si. To investigate the effects of P addition and holding time, hypereutectic Al-Si alloys with various amount of P content were produced in the lab. Then, the size and distribution of primary Si were examined respectively. Mechanical properties of hardness, tensile strength and wear resistance were analyzed in conjunction with the microstructural variations in alloys.
A Study on the Automatic Elimination of Free Edge for Sheet Metal Forming Analysis
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 614~622
DOI : 10.5228/KSPP.2004.13.7.614
A new approach for the automatic elimination of free edges in the finite element model for the analysis of sheet metal forming processes is presented. In general, the raw finite element model constructed from an automatic mesh generator is not well suited for the direct use in the downstream forming analysis due to the many free edges which requires tedious time consuming interactive graphic operations of the users. In the present study, a general method for the automatic elimination of free edges is proposed by introducing a CAD/CAE hybrid method. In the method a trimmed parametric surface is generated to fill the holes which are orginated from the free edges by using the one step elastic finite element analysis. In addition, mesh generation algorithm is suggested which can be used in the general trimmed surface. In order to verify the validity of the proposed method, various examples including actual automobile sheet metal parts are given and discussed.
Process Conditions for Low Bonding Strength in Pressure Welding of Cu-Al Plates at Cold and Warm Temperatures
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 623~628
DOI : 10.5228/KSPP.2004.13.7.623
This paper is concerned with pressure welding, which has been known as a main bonding mechanism during the cold and warm forming such as clad extrusion or bundle extrusion/drawing. Bonding characteristics between the Cu and Al plates by pressure welding are investigated focusing on the weak bonding. Experiments are performed at the cold and warm temperatures ranging from the room temperature to
. The important factors examined in this work are the welding pressure, pressure holding time, surface roughness, and temperature. A bonding map, which can identify the bonding criterion with a weak bonding strength of IMPa , is proposed in terms of welding pressure and surface roughness fur the cold and warm temperature ranges.
A Prediction of Bursting Failure in Tube Hydroforming Process Based on Necking Conditions
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 629~634
DOI : 10.5228/KSPP.2004.13.7.629
Based on plastic instability, analytical prediction of bursting failure on tube hydroforming processes under combined infernal pressure and independent axial feeding is carried out. Bursting is irrecoverable phenomenon due to local instability under excessive tensile stresses. In order to predict the bursting failure, three different classical necking criteria such as diffuse necking criterion for sheet and tube, local necking criterion for sheet are introduced. The incremental theory of plasticity for anisotropic material is adopted and then the hydroforming limit and bursting failure diagram with respect to axial feeding and hydraulic pressure are presented. In addition, the influences of the material properties such as anisotropy Parameter, strain hardening exponent and strength coefficient on bursting Pressure are investigated. As results of the above approach, the hydroforming limit in view of bursting failure is verified with experimental results.
A Study on Forging Process about Preform of Articulated Piston for Diesel Engine
Transactions of Materials Processing, volume 13, issue 7, 2004, Pages 635~641
DOI : 10.5228/KSPP.2004.13.7.635
Today the specific outputs of modern supercharger DI diesel engine for passenger cars reach values exceeding 50kw/1. By development of the articulated piston, specific output of up to 70kw/1 are sought. In doing so, peak cylinder pressure increases from the current 14-16MPa to 18-20MPa. The Articulated piston was composed Al cast skirt part and steel forged crown part. We have the target fer the design of forging process and die of the steel forged crown part. The design parameters of the forging process of the piston were obtained by the forging industry experiences and our experimental data and analysis result of finite element simulation. Especially, the design parameter of preform in blocker die was decided by finite element simulation using numerical package DEFROM3D. And also we can verify the design parameter by conducting visio-plasticity test using plasticine material. When we compared the results of analysis and experiment, a metal flow and load curve showed good agreement. Through this research, we could design optimal preform shape of articulated piston for this supercharged DI diesel engine.