• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.813-817
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• 1995

Structural analysis of horizontal cold chamber die casting machine is performed by the FEM. The analyzed model is made up of stationary die platen,movable die platen,link housing platen, C-frame, and tie bar which mainly undertake die locking force and injection force. In modeling, compression gap elements are used for to simulate contacting condition between tie bar and movable die platen, movable die platen and base frame, and link housing and base frame. Unbalanced die locking force imposed on four tie bars are considered. As the results, the deformed shape and the stresses of the die casting machine are given.

• 한국정밀공학회지
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• 제14권8호
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• pp.82-91
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• 1997

The major objective of this study is to establish analytical technique in order to analyze the behaviour of semi-solid material considering induction heating of the billet. Induction heating process is analyzed by using commerical finite element software. ANSYS. The finite element program, SFAC2D, for the simulation of deformation in semi-solid state is developed in the present study. The semi-solid behaviour is described by a viscoplastic model for the solid phase, and by the Darcy's law for the liquid flow. Simple compression and closed-die compression process considering induction heating are analyzed, and also it is found that the distribution of initial solid fraction of the billet has an important effect on deformation behaviour of semi-solid material. In order to verify the effectiveness of proposed analytical technique the simulation result is compared with experimental result.

• Design & Manufacturing
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• 제11권3호
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• pp.25-28
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• 2017

The production of carbon fiber reinforced thermoplastics(CFRTP) parts using an injection/compression molding process that differs from the conventionally used fabrication methods was investigated Before the application of composite molding in the injection/compression molding process, a simple compression molding experiment was performed using a hydraulic press machine to determine the characteristics of resin impregnation and to obtain a basic physical property data for the CFRTP. Based on these results, injection/compression molded specimens were manufactured and an additional insert/over molding process was applied to improve the impregnation rate of the molded specimens. The results demonstrated that the tensile strength of the molded parts using the faster injection/compression process was similar to that of a hydraulic press molded product.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 고액공존금속의 성형기술 심포지엄
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• pp.135-147
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• 1997

The production of light metal parts using aluminum is mainly performed by die casting and squeeze casting, which directly fabricate the required shape from the liquid state. However, die casting is subject to defects such as shrinkage porosity and air trapped when molten metal enters the cavity, whilst squeeze casting also has defects due to turbulent flow in the die cavity. Both diecasting and sqeeze casting have inhomogeneous mechanical property in terms of dendritic structure during solidification. Active research has been carried out on semi-solid processing, rather than on conventional process methods such as die casting, which involve various problems. Therefore in this paper, to introduce the fundamental technology for d e design, in die casting and forging process with semi-solid materials, relationship between stress and strain of semi-solid materials, and for producing parts die design has been proposed as parameters of globulization of the microstructure and gate shape. The prevention of various defects to produce sound parts are also introduced.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 금형가공 심포지엄
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• pp.43-53
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• 1998

Heat - affected zones degenerated in cold forging die have been investigated to improve the tool life. There are many cases of heat-affected zone which are degenerated in manufacturing die and using the cold forging process. In order to define amounts of grinding inmanufacturing the toolfor cold forging, we have investigated the hardness and microstructure of surface layer after EDM. Considering the results of T.R.S. and compression test, it is likely that mechanical properties of tool have been decreased sharply if the heat-affected zones degenerated by EDM were not machined properly. also analyzed the tool surfac which is fractured during the cold forging. According to the microstructures and hardness distribution, surface of many tools have been degenerated in cold forging and fractured due to the heat-affected zone.

• 소성∙가공
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• 제7권2호
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• pp.139-149
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• 1998

The technology of Semi-Solid Forging(SSF) has been actively developed to fabricate near net shape products using light and hardly formable materials. Generally the SSF process is composed of slug is compressed during a certain holding time in order to completely fill the die cavity and accelerate the solidification rate. The decision of compression time is important since it can affect microstructural characteristics, mechanical properties and shape of products.. In order to determine it proper overall heat transfer coefficient between the slug and dies should be investigated. This paper presents the procedure to find the overall heat transfer coefficient between the slug and dies by nonlinear optimization of temperature and solid fraction for a cylindrical slug at compression step in closed-die semi-solid forging. In finite ele-ment heat transfer analysis release of latent heat during solidification was considered. The influence of the predicted compression time on miscrostructural characteristics mechanimcal properties and shape of products is finally investigated by experiment.

• 대한기계학회논문집A
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• 제28권8호
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• pp.1140-1151
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• 2004

This paper reports on the finite elements analysis for die compaction process of cemented carbide tool parts. Experimental data were obtained under die compaction and triaxial compression with various loading conditions. The elastoplastic constitutive equations based on the yield function of Shima and Oyane were implemented into an explicit finite element program (ABAQUS/Explicit) and implicit finite element program (PMsolver/Compaction-3D) to simulate compaction response of cemented carbide powder during die compaction. For simulation of die compaction, the material parameters for Shima and Oyane model were obtained by uniaxial die compaction test. Explicit finite element results were compared with implicit results for cemented carbide powder.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.209-213
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• 2008

In this work, we have proposed a method for calculating the residual stress developed during the PCB thermo-compression bonding precess. Residual stress is the most important factor that causes PCB warpage in accordance with the pattern design. In this work, a single-layed double-sided PCB, which is comprised of the dielectric (FR-4) substrate in the middle and copper cladding on the both top and bottom sides, is considered. A reference temperature, where all stress is free, is calculated by comparing the calculated and measured warapge of a PCB of which copper cladding of the top side is removed. Then, the reesidual stress values is calculated for the double-sided PCB.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.467-468
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• 2007

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.191-192
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• 2006