Heechang Park

Development of roll-to-roll hot embossing system with induction heater for micro fabrication.

In this paper, a hot embossing heating roll with induction heater inside the roll is proposed. The induction heating coil is installed inside a roll that is used as a heating roll of a roll-to-roll (R2R) hot embossing apparatus. Using an inside installed heating coil gives the roll-to-roll hot embossing system a more even temperature distribution on the surface of the heating roll compared to that of previous systems, which used an electric wire for heating. This internal induction heating roll can keep the working environment much cleaner because there is no oil leakage compared to the oiled heating roll. This paper describes the principles and provides an analysis of this proposed system; some evaluation has also been performed for the system. A real R2R hot embossing heating roll system was fabricated and some experiments on micro-pattering have been performed. After that, evaluation has been performed on the results.

Effects of preheating and cooling durations on roll-to-roll hot embossing.

In this study, we examined the sensitivity of embossed pattern depth to preheat supply and cooling and investigated how the pattern type and density affect the embossed depth. The main factors that affect embossed pattern qualities of roll-to-roll hot embossing, such as roller temperature, roller speed, and applied force, were determined using the response surface methodology. Eight conditions were then added to determine the time-dependent effects of heat transfer with custom-designed preheating and cooling systems. An extended preheat time for the polymethylmethacrylate substrate contributed to the significant change in the embossed depth, whereas the substrate-cooling did not exhibit a clear increasing or decreasing trend. Larger embossed depths were achieved in the horizontal patterns with lower density than in the vertical patterns, and the lower pattern densities showed greater embossed depths in most embossing conditions. We expect that this result will help to understand the effects of the pre- and posttreatment of roll-to-roll hot embossing by employing time duration factors of heat transfer, depending on the mold pattern type and density.

Investigation of heat treatment of gears using a simultaneous dual frequency inducting heating method

This paper presented the simulation and experiment of gear hardening using the SDF induction technology . Using a thermal-electromagnetic coupled 2D FE model, it performed simulations on heating various gears and selected “optimal” input parameters of SDF induction heating . After constructing a 1 MW-scale SDF inducting heating system, gear hardening performances were evaluated . The trends of the experimental results matched with those of simulations . This study demonstrated the feasibility of 2-D FE modeling for reducing computational costs and accurately predicting gear hardening results “simultaneously” .

Thermal-electromagnetic Coupled Analysis for Gear Heat Treatment using Simultaneous Duel Frequency

In this paper, Finite Element Analysis (FEA) for gear heat treatment using simultaneous dual frequency (SDF) induction heating is conducted. To do this, thermal-electromagnetic coupled FE model is built. A two dimensional FE model of gear and heater is introduced to reduce computation time. For more time-efficient analysis, harmonic analysis for electromagnetic model is adopted and transient analysis model, for heat transfer model. Through the coupled analysis, it can be found that the proposed FE model can solve for SDF induction heating of gear and heat treatment parameters can also be determined.

Development of Heater Using Eddy Current

In this research, a heater using eddy current for generator is designed and some analysis is performed to validate the system. FEM (finite element method) is used for analysing eddy current phenomena at the various speed of rotor with permanent magnet. A real heater system is fabricated. Some experiment is also performed to validate the analysis result. Through the experiment, the FE analysis is validated and we found that the efficiency of developed heater is over 94%.

A Simulator for Train Detection and its Control by Inductive Radio Line

A rotating experimental unit for train control is described and a train detection method using an inductive radio line is adopted. In this unit, the inductive radio line spread over the rotor plate and the receiving antennas are placed on the stator side. The detection circuits for train position and speed are described and an application of train control using a PID controller is presented.

Analysis on small particles heating using electromagnetic excitation

This paper describes the analysis of the induction heating of the small particles in the polymer. Especially, we focus the micro or nano size magnetic particles in the adhesive for shoe manufacturing. To analyze the induction heating of the particles, a novel analytical procedure is suggested, which combines the Finite Element Method and theoretical equations. Temperature variations over time is calculated and the results are compared with the experiments. This comparison shows the effectiveness of the proposed method.

Effects of Preheat Supply on Embossed Pattern Depth in Roll-to-Roll Process

In this study, we examined the sensitivity of embossed pattern depth to preheat supply and cooling, and also tested how pattern type and density affect the embossed depth. The main factors such as roller temperature, roller speed, and applied force that mostly affect embossed pattern qualities of roll-to-roll hot embossing were determined based on the response surface methodology. Eight conditions were then added to know the time-dependent effects of heat transfer with custom designed preheating and cooling systems (Fig. 1). Extended preheat time for the PMMA substrate contributed to the significant change of the embossed depth, whereas the substrate-cooling showed no straightforward increasing or decreasing trend. Larger embossed depths were achieved in horizontal patterns with lower density compared to vertical patterns, and the lower pattern densities showed the greater embossed depths regardless of pattern types. We expect that this result may help to understand the effects of preand post-treatment of roll-to-roll (R2R) hot embossing by employing time duration factors of heat transfer, depending on mold pattern type and density.

Study on the roll-to-roll hot embossing with a presurized belt

In this paper, we proposed a new method to increase the pattern quality on the polymer film graved by a roll-to-roll hot embossing apparatus. To expand the curing time during roll-to-roll hot embossing process, a belt is used around the patterned roller. This belt applies pressure on the film and patterned roller while the generated pattern cools down. To validate the feasibility of the proposed mechanism, a real roll-to-roll hot embossing system is fabricated and experiments are performed.

Analysis of Pneumatic Balloon Actuator

This paper describes the analysis of Pneumatic Balloon Actuator (PBA). To do this, Finite Element Method (FEM) is used. In this paper, no-load characteristic of PBA is studied and through this, the displacement and stress of PBA can be calculated.