• Transactions of Materials Processing
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• v.20 no.6
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• pp.439-449
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• 2011

The temperature distribution and subsequent permanent deformation of SS400 carbon steel plate subjected to an induction-based line heating process were studied by a numerical method involving coupled 3-D electromagnetic-thermal-structural analysis. The numerical study revealed that the amount of permanent deformation is strongly related to the Joule loss caused by such process conditions as input power and moving speed of the heat source. To validate the numerical analysis results, line heating experiments were carried out with a high frequency(HF) induction heating(IH) equipment capable of bending thick plate with the moving accuracy of ${\pm}0.1mm$ in heating coil position. The amount of permanent deformation increased with decreasing moving speed and increasing input power.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.4
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• pp.417-425
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• 2008

In the line heating process, only angular distortion whose direction is perpendicular to that of a heating path is expected. However, it is observed that a deformation is induced in the direction of the heating line. Because of this, during forming a saddle type plate we experience unfavorable deformations in the unintended direction. In this paper we discuss the unwanted distortion in the manufacturing process by analyzing intermediate plates of saddle type during fabrication. For this analysis we consider the longitudinal and transversal directions separately and use the bending strain for the analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.738-742
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• 2006

In this study we developed the electrical heating mold core by applying three different heating methods. In order to find out the optimal heating method, we observed the temperature profiles with time. We also injection-molded the parts by the heating methods and investigated the shrinkage ratio, density, surface roughness and weld-lines. The temperature rise time and cycle time showed the promising results for commercial applications(the rise time is $130^{\circ}C$/14sec, the cycle time is 55sec). By comparing with the conventional and gas flame heating method, the parts by this method were proven to have good qualities. The shrinkage ratio reduced by 5.1%, the density increase by 2.66%, the smoothness increased about 3 times, and the weld-line did not observed by naked eyes.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.2
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• pp.104-113
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• 1998

The line heating method is a popular technique used to form ship hull in shipyards. In order to promote shipbuilding productivity, some researchers have made progress in their studies on automatic fabrication system for plate forming. These researches have, however, focused on heat-induced plate deformation with particular mechanical modelings, and do not yet propose the heating paths applicable to actual plate forming process. In this paper, a new algorithm to determine heating lines is developed to simulate the line heating process. The important feature of this algorithm is that it calculates principal curvatures of deflection difference surface which represents difference between target surface and surface in fabrication. Several trials to typical surface types show its usefulness and good applicability to tactical use.

• 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.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.5
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• pp.670-678
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• 1997

A method to mitigate the thermal stratification phenomenon of pressurizer surge line is proposed by heating bottom outside of horizontal pipe. Unsteady two dimensional model has been used to numerically investigate an effect of heating the bottom of pipe. The dimensionless governing equations are solved by using the control volume formulation and SIMPLE algorithm. Temperature and streamline profiles of fluids and pipe walls with time are compared with the previous study result. The numerical result of this study shows that the outside heating can relaxate the thermal stratification flow of the pressurizer surge line. Maximum dimensionless temperature difference between hot and cold sections of the pipe inner wall which causes thermal stratification was reduced from 0.514 to 0.424 at dimensionless time 1, 632 and 1, 500 respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2470-2476
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• 2011

Inherent strain method, a hybrid method of experimental and numerical, is known to be very efficient in predicting the plate deformation due to line heating. For the simulation of deformation using inherent strain method, it is important to determine the magnitude and the region of inherent strain properly. Because the phase of steel transforms differently depending on the actual speed of cooling following line heating, it should be also considered in determining the inherent strain. A heat transfer analysis method including the effects of impinging water jet, film boiling, and radiation is proposed to simulate the water cooling process widely used in shipyards. From the above simulation it is possible to obtain the actual speed of cooling and volume percentage of each phase in the inherent strain region of a line heated steel plate. Based on the material properties calculated from the volume percentage of each phase, it should be possible to predict the plate deformations due to line heating with better precision.

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.149-151
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• 2002

In this study, a formula for thermal processing induced plate deformations, in terms of process parameters such as heat input and plate thickness, is developed analytically using an infinite laminated plate theory to consider cuboidal inclusion with an eigenstrains. When a plate has arbitrary heating lines, complex deformed shape of plate was calculated by the method estimating plate deformation proposed by this study. To make a curved surface of the ship hull, the line heating method is mainly used. Application in automatization of line heating was deliberate by using proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.21-22
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• 2009

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1754-1759
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• 2008

To produce plastic parts that have fine pattern through conventional injection molding, a lot of difficulties follow. Therefore, rapid heating and cooling methods are good candidates for manufacturing injection-molded parts with micro/nano patterns. In this study, we adopted the E-Mold patent technology. The mold for E-Mold technology has a separate heated core with micro heaters. It is very important to optimize the lay-out of the heaters in heated core because it influences both control and distribution of mold temperature. We developed a optimization method of heating line lay-out by using commercial softwares and compared the output with the experimental results. We used Pro-Engineer Wildfire 2.0 for the mold design, ICEMCFD for mesh generation, and FLUENT for heat transfer simulation. The simulation results showed the temperature profile from $60^{\circ}C$ to $120^{\circ}C$ or $180^{\circ}C$ during heating and cooling process which were compared with the injection molding experiments. We concluded that the simulation could well explain the experimental results. It was shown that the E-Mold optimization design for heater lay-out could be available through the simulation.