• Journal of Ocean Engineering and Technology
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• v.22 no.6
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• pp.83-87
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• 2008

Although a great deal of research has been carried out to solve the plate forming problem and to improve the effectiveness and productivity of the plate forming process, no practical way of automating the plate forming process has been proposed yet. Since characteristics of heating machines may vary, it is necessary to investigate the thermal deformation characteristics of the heating machine that will be used in the automation system its characteristics may be modified as new information about thermal deformation by heating becomes available. In this paper, experiments for line heating have been carried out to calculate the formula of predicting thermal deformation due to line heating with varying affecting parameters, and numerical study has been carried out to produce data beyond the range where a line heating test is impractical. Formulas of predicting transverse distortion and shrinkage have been proposed and derived, based on the present experimental and numerical works. This paper also illustrates how the formula has been modified as new experimental data are added.

• Journal of Welding and Joining
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• v.28 no.1
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• pp.92-99
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• 2010

For the last couple of decades many studies have been carried out to find out solutions to improve the effectiveness and productivity of the plate forming process. The practical way for the automation of the plate forming process has not been, however, developed yet. Since the characteristics of heating machines may be different form each other, it is necessary to investigate the thermal deformation characteristics of the heating machine to be used in the automation system. And their characteristics may be updated as new information about thermal deformation by heating is accumulated. In this paper, data base system has been constructed based on the results of experiments and numerical analyses, which will be used in deriving the deformation estimation formula. The computer code which can automatically derive the deformation estimation formula has been also developed. This paper also illustrates how the formula is updated as experimental data are added. From the present findings, it can be said that the automatic deriving procedure may be important in the automated plate forming system since the heating line information to be generated must be directly influenced by the deformation estimation formula.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.202-205
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• 1995

Developed controller is the part of deflection yoke winding machine which controls the power to form the deflection yoke coil into desired shape after winding. So as to form the deflection yoke coil, it is needed to melt the bonding material which is spreaded on the coil. The heat melt the bonding material which is produced by flowing the current through the winded coil. Therefore, at first it is needed to peel off the enamel from the winded coil so as to flow the current, and then supply the power to produce the heat which form the winded coil into desired shape. Naturally developed controller is composed of the peeling part and the conduction and forming part. All of them consist of the inverter structure and control the output current. The peeling is achieved by low voltage and high AC current, the conduction and forming is by DC current. Developed controller also has a function that detect the resistance of the deflection yoke coil to prevent the damage of the load which is produced by poor peeling.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.397-400
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• 2007

Recently, rheology forming technology has been interested in industrial and academic for light weight materials and to solve environmental issues. In this study, the rheology material production equipments were used to be made spiral shape by special design. And the experiment variables established stirring time 0 $\sim$ 1200 sec, stirring velocity 0 $\sim$ 100 rpm and several material temperature of semi - solid states. The rheology materials were made for established experiment conditions then measured mechanical properties. Sequence-production equipments were appended to fabrication system of rheology material for make rheology materials continually. Therefore, the development of sequence-production equipments were demanded for fine grains and for uniform globule shape rheology materials by a specially designed spiral stirrer machine.

• Transactions of Materials Processing
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• v.26 no.2
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• pp.121-126
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• 2017

The hot stamping process is an innovative forming method that could prevent the cracking of high strength steel sheets. The formability test of boron steel sheet using forming limit diagrams at elevated temperature is very complicated and time consuming job. In this paper, an alternative test method to evaluate the formability of boron steel in hot stamping has proposed. It measured the FLD0 instead of whole strain combinations of FLD with the tensile test machine and specially designed test rig. Test results shows that the proposed test method can simulate the plain strain condition fracture and can make the FLD of boron steel sheet at elevated temperature with less effort.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.261-264
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• 2003

Semi-solid processing is now becoming of great interest for the production of various parts by pressure die casting. Many advantages are associated with this forming process at the condition that the forming operation is performed under appropriate conditions. The thixoforming process, which needs a suspension of a globular, non-dendritic solid phase in the liquid phase, is characterized by three major steps. The first step is casting of billets with a microstructure suited for thixoforming. The second step is reheating of slugs cut from these billets. The third step is injection of the semi-solid slugs into a die. In this paper, the horizontal reheating machine to obtain the optimal conditions suitable for semiu-solid die casting process was used and applied to extrusion material. It is estimated the possibility of application on semi-solid die casting with extrusion material through various results.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.124-128
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• 2004

By the use of a similar numerical method as that in the previous paper, the forming limit strain by coaling method of clad sheet metals is investigated, in which the FEM is applied and J2G(J$_2$-Gotoh's corner theory) is utilized as the plasticity constitutive equation. Declined Multilayer Metals Materials are stretched in a plane-strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such composite sheets are clearly illustrated. It is concluded that, in the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighted according thickness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.560-563
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• 2004

Invar is a compound metal of Fe-Ni system and contain 36％ Ni. The most distinction characteristic of Invar is the coefficient of thermal expansion is 1.0 10$^{-6}$ /$^{\circ}C$. That is a tenth of general steel material. This low thermal expansion characteristic of Invar is applied to the missile, aircraft, monitor CRT and frontier display's shadow mask such as FED and OLED. The usage of the Invar shadow mask for display is increasing due to the requirement of larger size and flatness monitor. The Invar shadow mask is machined by two ways electro-forming and laser now. However the electro-forming takes a too long time and the laser machining is accompanied with Burr. In this study, PEMM(pulse electrochemical micro machining) is conducted to machine the micro hole to the Invar and 80${\mu}{\textrm}{m}$ hole was machined.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.3-8
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• 2001

This study is an investigation for the ADS optimum design by using FEA. We write out program which express ADS perfectly and reduce the required time for correcting of model to the minimum in solution and manufacture result. We complete algorithm which can plan optimum forming of model by feedback error information in CAE. Then we correct model by feedback date obtaining in solution process, repeat course following stress solution again and do modeling rachet wheel for optimum forming. That is our aim. In rachet wheel, greatest equivalence stress originates in key groove corner and KS standard is proved the design for security.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.406-411
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• 2003

It is clearly demonstrated that deeper cups could be formed by single and double stretch-drawings from smaller circular blanks due to such wall-thinning action than in the usual deep-drawing of larger blanks. From this fact, it is emphasized that the deep-drawability of a sheet metal Is not evaluated simply by the conventional L.D.R (limiting drawing ratio), but the depth of the drawn cup should also be taken into account. Many experimental data about various metals and thicknesses given in this paper offer a valuable information in this process for more general use which recommends to replace the conventional deep-drawing process by the stretch-drawing process both for single and double operations. In the single stretch-drawing, it is also confirmed that a deeper cup can be produced by raising the blank-holding force at later stage of operation.