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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 19, Issue 8 - Dec 2010
Volume 19, Issue 7 - Nov 2010
Volume 19, Issue 6 - Oct 2010
Volume 19, Issue 5 - Aug 2010
Volume 19, Issue 4 - Jul 2010
Volume 19, Issue 3 - Jun 2010
Volume 19, Issue 2 - Apr 2010
Volume 19, Issue 1 - Feb 2010
Selecting the target year
Die System for Avoiding Thickness Reduction along the Bent Corner in Warm Plate Forging of an Axle Housing
Kim, J.S. ; Kim, K.S. ; Shim, S.H. ; Eom, J.G. ; Joun, M.S. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 447~451
DOI : 10.5228/KSTP.2010.19.8.447
In this paper, a useful die system for warm plate forging of a large axle housing of heavy-duty trucks is presented. A die system composed of material flow guide pin as well as upper die and lower die is proposed to reduce the inherent thickness reduction along the bent corner of the product which deteriorates structural strength and fatigue life in its service. The role of the pin assembled in the upper die is to prevent formation of sharp corner in early forming stage and to supply material in the lower die cavity sufficient enough to thicken the bent corner at the final stroke. The mechanism of the die system is given and its effect on corner thickness of the product is revealed by two-dimensional finite element analysis under plain strain assumption. Three-dimensional finite element solutions are also given to verify validity of the two dimensional approach and to show the mechanics of the die system in detail. The die system has been successfully applied to manufacturing the axle housing of heavy-duty trucks.
A Study on Extru-Shear Welding(ESW) Process of Aluminum Plates
Lee, K.K. ; Lee, M.Y. ; Jin, I.T. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 452~459
DOI : 10.5228/KSTP.2010.19.8.452
It was investigated that two plates of aluminum can be welded by hot extru-shear welding process with extru-shear welding dies, and that the welding strength and metal flow on the welding section were analyzed by computer simulation according to the welding variables such as inclined angle of cutter and overlapped length of plates and temperature of plates. It was known by computer simulation that welding strength on the welding section of plates could be influenced by the inclined angle of cutter and overlapped length of plates and temperature of plates. And it was known by experiments that two plates of aluminum can be welded on the end sections by hot extru-shear welding process using extru-shear welding dies, and that welding strength is the highest when inclined angle of dies is
, and overlapped length is 1.2 mm, and temperature is
, when aluminum 5052 two plates with 1.6 mm thickness are used as welding material.
A Study on Welding Strength of Extru-Riveting Process of Aluminum Plates
Lee, J.H. ; Kim, T.H. ; Lee, M.Y. ; Jin, I.T. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 460~467
DOI : 10.5228/KSTP.2010.19.8.460
It was studied that two plates of aluminum can be welded by extru-riveting experiments with extru-rivet welding dies, and that the welding strength and metal flow on the welding section were analyzed by computer simulation according to the welding variable such as the diameter of extrusion insert dies. It was known by computer simulation that welding strength on the welding section of plates could be influenced by the diameter of extrusion insert dies. And it was known by experiments that two plates of aluminum can be welded on a spot point on aluminum plate by extru-rivet welding process, and that welding strength is higher and higher if the diameter of extrusion insert die is smaller and smaller, and that welding strength is the highest when diameter of extrusion insert dies is
mm in the case that the diameter of rivet is 5 mm, when aluminum 5052 two plates with 1.5 mm thickness and one plate with 3mm thickness for rivet plate are used as welding material.
A Phenomenological Constitutive Model for Pseudoelastic Shape Memory Alloy
Ho, Kwang-Soo ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 468~473
DOI : 10.5228/KSTP.2010.19.8.468
Shape memory alloys (SMAs) have the ability to recover their original shape upon thermo-mechanical loading even after large inelastic deformation. The unique feature is known as pseudoelasticity and shape memory effect caused by the crystalline structural transformation between two solid-state phases called austenite and martensite. To support the engineering application, a number of constitutive models, which can be formally classified into either micromechanics-based or phenomenological model, have been developed. Most of the constitutive models include a kinetic law governing the crystallographic transformation. The present work presents a one-dimensional, phenomenological constitutive model for SMAs in the context of the unified viscoplasticity theory. The proposed model does not incorporate the complex mechanisms of phase transformation. Instead, the effects induced by the transformation are depicted through the growth law for the back stress that is an internal state variable of the model.
A Study on Design of High Luminance Hybrid LED Package and Ultra-fine Machining of Optical Pattern
Jeon, E.C. ; Je, T.J. ; Whang, K.H. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 474~479
DOI : 10.5228/KSTP.2010.19.8.474
Newly suggested hybrid LED package can reduce the number of LED processes and enhance light efficacy in virtue of its integrated optical patterns. Square-type pyramid pattern was chosen for the integrated optical pattern in this study, and it was proved that the pattern enhances illuminance about three times and luminance about two and half times by optical simulation. Square-type pyramid patterns of 0.02mm height and 0.04mm pitch were successively machined on a copper mold which is necessary for imprinting the integrated pattern. Hybrid LED package with integrated optical pattern will be manufactured with ultra-fine machined mold in future study.
Void Closing Conditions of Large Ingot by Path Schedules
Choi, I.J. ; Choi, H.J. ; Kim, D.W. ; Choi, S. ; Lim, S.J. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 480~485
DOI : 10.5228/KSTP.2010.19.8.480
In this work, the closing behavior of cylindrical-shaped voids was experimentally investigated according to various parameters such as reduction ratio in height, initial void size and billet rotation during hot open die forging process. The reduction ratio in height, number of path, and billet rotation were chosen as key process parameters which influence the void closing behavior including the change of void shape and size. On the other hand, values of die overlapping and die width ratio were set to be constant. Void closing behavior was estimated by microscopic observation. Based on the observations, it was confirmed that application of billet rotation is more efficient to eliminate the void with less reduction ratio in height. The experimental results obtained from this study could be helpful to establish the optimum path schedule of open die forging process.
Tendency Analysis of Shape Error According to Forming Parameter in Flexible Stretch Forming Process Using Finite Element Method
Seo, Y.H. ; Heo, S.C. ; Song, W.J. ; Kim, J. ; Kang, B.S. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 486~493
DOI : 10.5228/KSTP.2010.19.8.486
A shape error of the sheet metal product made by a flexible stretch forming process is occurred by a various forming parameters. A die used in the flexible stretch forming is composed of a punch array to obtain the various objective surfaces using only one die. But gaps between the punches induce the shape error and the defect such as a scratch. Forming parameters of the punch size and the elastic pad to prevent the surface defect must be considered in the flexible die design process. In this study, tendency analysis of shape error according to the forming parameters in the flexible stretch process is conducted using a finite element method. Three forming parameters, which are the punch size, the objective curvature radius and the elastic pad thickness, are considered. Finite element modeling using the punch height calculation algorithm and the evaluation method of the shape error, which is a representative value for the formability of formed surface, are proposed. Consequently, the shape error is in proportion to the punch size and is out of proportion to the objective curvature radius and the elastic pad thickness.
Sensitivity of Dimensional Changes to Interfacial Friction over the Definite Range of Friction Factor in Ring Compression Test
Lim, J.Y. ; Noh, J.H. ; Hwang, B.B. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 494~501
DOI : 10.5228/KSTP.2010.19.8.494
The main objective of this study is to examine the sensitivity of calibration curves of FEA of ring compression test to frictional shear factor. Ring compression test has been investigated by measuring dimensional changes at different positions of ring specimen and they include the changes in internal diameter at the middle and top section of the specimen, outer diameter at the middle and top section, surface expansion at the top surface, respectively. Initial ring geometries employed in analysis maintain a fixed ratio of 6 : 3 : 2, i.e. outer diameter : inner diameter : thickness of the ring specimen, which is generally known as `standard` specimen. A rigid plastic material for different work-hardening characteristics has been modeled for simulations using rigid-plastic finite element code. Analyses have been performed within a definite range of friction as well as over whole range of friction to show different sensitivities to the interfacial friction for different ranges of friction. The results of investigation in this study have been summarized in terms of a dimensionless gradient. It has been known from the results that the dimensional changes at different positions of ring specimen show different linearity and sensitivity to the frictional condition on the contact surface.
Texture and Plastic Strain Ratio Changes with the Number of Passes of Asymmetric Rolling in AA1050 Al Alloy Sheet
Nam, Su-Kwon ; Jeong, Hae-Bong ; Kim, In-Soo ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 502~507
DOI : 10.5228/KSTP.2010.19.8.502
The physical and mechanical properties and formability of sheet metals depend on preferred crystallographic orientations (texture). In this research work, the texture development and formability (plastic strain ratios) of AA1050 Al alloy sheets after 3 and 10 passes of asymmetric rolling and subsequent heat treatment were investigated. The plastic strain ratios of 10 passes asymmetrically rolled and subsequent heat treated samples are 1.3 times higher than those of the initial AA1050 Al alloy sheets. The
of 10 passes of asymmetrically rolled and subsequent heat treated samples is 1/30 times lower than those of the initial AA1050 Al alloy sheets. The plastic strain ratios of 10 passes of asymmetrically rolled and subsequent heat treated Al sheets are higher than those of 3 passes ones. These results could be attributed to the formation of
-fiber, ND//<111>, and the other texture components by means of asymmetric rolling in Al sheets.
Progressive Die Design for a Component of Double Sinks with Locally Thickened Wall
Jang, W.S. ; Choi, H.S. ; Lee, H.D. ; Gang, S.C. ; Ahn, K.C. ; Kim, B.M. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 508~516
DOI : 10.5228/KSTP.2010.19.8.508
Thickening process in sheet metal forming is being increased to improve the strength as well as to reduce manufacturing process such as welding. This process can make it possible to obtain part locally thicker than that of initial sheet thickness. In this study, design method for manufacturing the component which has double sinks with local thickened wall is proposed. Deep drawing and upsetting processes are applied in order to form double sinks and thicken its walls. Used material is SPHC440 with the thickness of 2.0mm and initial blank size is determined on the basis of the final product. Distance between the center of double sinks and first drawing ratio to avoid fracture are the most significant factors during deep drawing. FE-analysis is implemented in order to determine the appropriate values. Progressive die is designed based on the proposed method and FE-analysis. As a result of experiment, locally thickened component can be manufactured, which has double sinks with the thickness about 3mm at the corner and wall.
Process Analysis of Melting Behaviors in Selective Laser Melting Process
Sung, M.Y. ; Joo, B.D. ; Kim, S.H. ; Moon, Y.H. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 517~522
DOI : 10.5228/KSTP.2010.19.8.517
Selective laser melting (SLM) is emerged as a new manufacturing technique to directly fabricate precise parts using metallic materials. The final characteristics of a component fabricated through the SLM process are strongly dependent upon various parameters such as laser power, scan rate and pulse duration, etc. This paper, therefore, focuses on the dimensional characteristics of melted
Fe-Cr-Ni powder by fiber laser for the selective laser melting process. With energy density decrease, the height and depth were decreased. Although the conditions are of the same energy density, the shape is different by laser power and scan rate. The shapes at various laser parameters were divided into 3 groups based on depth over height. The smooth regular shape is obtained under the conditions of
of powder height and
of pulse duration. And the laser power influenced the variation of shape more significantly than the scan rate.
Analysis of Forging Technology based on Investigation of Production Cost in the Korean Forging Industry
Lee, H.W. ; Choi, S. ; Bae, S.M. ;
Transactions of Materials Processing, volume 19, issue 8, 2010, Pages 523~528
DOI : 10.5228/KSTP.2010.19.8.523
The forging industry is composed of those plants that make parts to order for customers; or make parts for their own company`s internal use; or make standard parts for resale. Also, the forging industry is closely related with automobile industry and ship building industry - Korea`s major export industry. But, it is hard to find the Korea`s forging industry`s statistical analysis because it is not revealed with final product. In this paper, we perform statistical analysis using the micro data service provided by the Statistics Korea. We focus on the analysis of production costs as well as the status of forging company and their employee.