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Lee, ChaBum,Kuriyagawa, Tsunemoto,Woo, Do-Kyun,Lee, Sun-Kyu IOP 2010 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.20 No.5
<P>This paper presents the experimental investigation of an optimal hot embossing process to prevent the nanoscale thermal deformation of microstructures replicated from the electroless Ni mold fabricated by the diamond tool-interfered scribing method. A polymer-based PMMA was replicated from the mold with the blazed profile: period 2.0 µm and depth 0.2 µm. The molding conditions, the applying pressure (<I>P<SUB>m</SUB></I>), molding temperature (<I>T<SUB>m</SUB></I>) and demolding temperature (<I>T<SUB>d</SUB></I>) were chosen as experiment parameters. In terms of the quality of surface smoothness, profile, sharp edge, surface roughness and optical performance of the replica, the conditions, <I>P<SUB>m</SUB></I> = 0.9 MPa, <I>T<SUB>m</SUB></I> = 150 °C and <I>T<SUB>d</SUB></I> = 20 °C, showed a best results. From optical testing, diffraction efficiency of the replica was measured, 87.6%, and the replica molded in other conditions showed a noticeable efficiency drop due to the molding error.</P>
황연(Yeon Hwang),T.Kuriyagawa,이선규(Sun-Kyu Lee) 한국정밀공학회 2005 한국정밀공학회 학술발표대회 논문집 Vol.2005 No.10월
This paper presents a geometrical error analysis of wheel curve generation method for micro aspheric surface machining using parallel grinding method. In aspheric grinding, wheel wear in process is crucial parameter for profile error of the ground surface. To decrease wheel wear, parallel grinding method is adopted. Wheel and work piece (Tungsten carbide) contact point changes during machining process. In truing process of the wheel, radius is determined by the angle and distance between wheel and truer. Wheel radius error is predominantly affected by vertical deviation between the wheel rotation center and the truer center. Simulation for vertical error and wheel radius error shows same tendency that expected by geometrical analysis. Experimental results show that the analysis of curve generation method matches with simulations and wheel radius errors.
Improvement of Glass Formability in Ultrasonic Vibration Assisted Molding Process
Tianfeng Zhou,Jiaqing Xie,Jiwang Yan,Kuriyagawa Tsunemoto,Xibin Wang 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.1
Micro optical elements with complex shapes are needed increasingly in optical, optoelectronic and biomedical industries. Since glass molding process is an effective approach to fabricate microstructures, and its surface quality strongly depends on the filling capacity of glass at high temperature. To improve the formability and reduce adhesion between the glass and the mold at high temperature, ultrasonic vibration is applied to improve the formability in the molding process. Fundamental experiments are carried out to test the effectiveness of ultrasonic vibration on friction force decrease and a bonding model on the glass-mold interface at elevated temperature is proposed. Finite element method (FEM) simulation and glass molding experiments are conducted to evaluate the improvements of material formability brought about by ultrasonic vibration. The results show that the ultrasonic vibration can significantly lower the friction force and increase the glass formability.
Minimization of Hydrodynamic Pressure Effect on the Ultraprecision Mirror Grinding
Sun-Kyu Lee,Yuji Miyamoto,Tsunemoto Kuriyagawa,Katsuo Syoji 한국정밀공학회 2005 International Journal of Precision Engineering and Vol.6 No.1
This paper describes an investigation about the fluid delivering method that minimizes the generation of hydrodynamic pressure and improves the grinding accuracy. Traditionally, grinding fluid is delivered for the purpose of cooling, chip flushing and lubrication. Hence, a number of conventional investigations are focused on the delivering method to maximize fluid flux into the contact arc between the grinding wheel and the work piece. It is already known that hydrodynamic pressure generates due to this fluid flux, and that it affects the overall grinding resistance and machining accuracy. Especially in the ultra-precision mirror grinding process that requires extremely small amount of cut per pass, its influence on the machining accuracy becomes more significant. Therefore, in this paper, a new delivering method of grinding fluid is proposed with focus on minimizing the hydrodynamic pressure effect. Experimental data indicates that the proposed method is effective not only to minimize the hydrodynamic pressure but also to improve the machining accuracy.