• Polymer Science and Technology
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• 제20권2호
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• pp.157-169
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• 2009

• Journal of Korea Foundry Society
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• 제22권4호
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• pp.155-159
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• 2002

Magnesium alloys have high strength to weight ratio and are extremely attractive for applications in transport industry. Most of structural magnesium alloys are manufactured by die casting process. The tensile properties of AZ91HP magnesium alloy were investigated after die casting under various die casting conditions. After die casting by using cold chamber machine, the volume porosity of specimens was examined with density method. With the increase of the volume porosity of specimens, both the tensile strength and elongation were significantly decreased, however the 0.2% offset strength was almost independent of the amount of porosity. With the increase of crystal pressure from 500 to 900 bar during die casting, the volume porosity was decreased, which resulted in the increase of the tensile strength. The mould temperature within the range of $150{\sim}250^{\circ}C$ has not influenced the microstructure with the eutectic phase and tensile properties of specimens. The tensile strength was the highest at 90m/sec of gate speed.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제19권40호
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• pp.143-155
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• 1996

Presented in this paper are a CAPP(Computer Automated Process Planning) scheme and a generating method of intelligent NC data for unmaned machining of mold die. Mold die surfaces usually have free-formed geometry of complex shapes. So it is easy to overcut the die surface and to overload the cutting tools. It takes tens of hours to prepare process plans and to generate NC data for each processes. Therefore a classification of unit machining operation(UMO) for mold die manufacture, a backward recursive capp algorithm and a generating method of intelligent NC data are presented in this paper in order to provide a unmaned machining architecture of mold die.

• Journal of the Korean Society for Precision Engineering
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• 제17권6호
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• pp.162-168
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• 2000

The automatic die polishing machine by liquid honing has been developed and experimented on the surface of machined die. The goal of development in the automatic die polishing machine by liquid honing is to increase the accuracy and the productivity in die polishing. To reach this goal, the polishing machine consists of the automatic measuring device for contour of die, the nozzle and pumping system to spray the powder mixed with liquid, and the 3-axis guides. Before polishing, the measuring device with a semiconductor laser scans the surface of mould to get the data of contour. The data store a PC and use to control the nozzle head to move above a couple of centimeters on the machined surface of die. The experimental parameters are the spraying time, the pressure, the size of abrasive grain and the mixing ratio between abrasive grain and liquid. The surface roughness is measured on the polished die which are SKDl 1 and Al7075 machined by NC. The surface roughness indicates the values of Rmax 0.5${\mu}{\textrm}{m}$ for Al7075 and Rmax 1.4${\mu}{\textrm}{m}$ for SKDl 1. It reduces the polishing time significantly and reduces the monotonous work for labors. As the results, the liquid honing system is useful method to apply for the die polishing and the automatic die polishing machine using liquid honing shows that it's very effective processing ability.

• Transactions of Materials Processing
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• 제21권3호
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• pp.195-201
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• 2012

A vacuum ladling die casting system is suggested as a means to obtain a high vacuum level. A high vacuum of 17.8 mmHg is obtained by sealing the inner space of the mould. The sample product is a rear-head housing for an auto-compressor, and the die-casting with 6-cavities was conducted. The flow analysis shows that the filling speed during vacuum ladling is faster than for a non-vacuum system. The air holes in the sample product were too small to be seen with the naked eye in X-ray films. Density tests show that the high vacuum ladling system reduces the internal porosity as much as 57.8% when compared to the non-vacuum system. A defective rate of only 0.17% was found from leak testing. The results of this research prove that the high vacuum die-casting process is useful for manufacturing of aluminium components under high internal pressure.

• Journal of the Korean Society of Safety
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• 제7권1호
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• pp.39-45
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• 1992

The impulsive stress and wave propagation of a glass/epoxy laminate subjected to the transverse low-velocity impact of a steel ball are investigated theoretically and experimentally. A plate finite element model based on Whitney and Pagano's theory In consunchon with experimental contact laws is used for the theoretical investigation. The specimens fo, statical indentation and impact test we composed of ［0/45/0/-45/0］$_{2s}$ and ［90/45/90/-45/90］$_{2s}$ stacking sequences and have clamped-simply supported boundary conditions. Finally, these two results are compared and then the impulsive stress and wave propagation characteristics of this laminated composite are studied.ied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.153-154
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.95-96
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• 2006

This study examined the effects of the tempering temperatures($360-420^{\circ}C$) on the mechanical properties of the carbon tool steel (SK4M) for flat spring. Hardness test, tensile test and fatigue test were performed at room temperature($20^{\circ}C$). The tensile strength and yield strength of $390^{\circ}C\;and\;420^{\circ}C$ tempered SK5M were 0.93-0.97 times and 0.81-0.87 times those of $360^{\circ}C$ tempered SK5M, respectively. The fatigue limit of $360-420^{\circ}C$ tempered SK5M were 35-40% of tensile strength of $360-420^{\circ}C$ tempered SK5M, respectively.

• Korean Journal of Computational Design and Engineering
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• 제7권3호
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• pp.141-147
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• 2002

Profile machining using cutter diameter compensation is widely used in die and mould manufacturing. Especially automotive die makers try to use 3D-profile machining for trimming or flange dies. But the technological requirements and implementation issues haven't been defined. In this paper we summarized the requirements and issues of 3D-profile machining. Approximation of input profiles into sequences of line and helical arc is the first major issue. The second major issue is removing cutter inter- ference from the approximated curves holding z-values when the maximum cutter diameter is given. Keeping constant machining width, local machining, path linking problems and several detail technological requirements are also discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.19-25
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• 2002

Profile machining using cutter diameter compensation is widely used in die and mould manufacturing. Especially automotive die makers try to use 3D-profile machining for trimming or flange dies. But the technological requirements and implementation issues haven't been defined. In this paper we summarized the requirements and issues of 3D-profile machining. Approximation of input profiles into sequences of line and helical arc is the first major issue. The second major issue is removing cutter interference from the approximated curves holding z-values when the maximum cutter diameter is given. Keeping constant machining width, local machining, path linking problems and several detail technological requirements are also discussed.