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RISS 인기검색어
- 검색키워드
- 저자 : Shun-Tong Chen (검색결과 4 건)
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Shun-Tong Chen,Wei-Yu Jhou 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.4
This study examines the development of a “dual-crankshaft out-of-phase balanced drive mechanism” and its application in the realization of high-frequency scraping in the production of highly precise, extremely dense microconcavity patterns. The high-density microcavity mold can produce micro-lens arrays, which achieve energy saving through the light-gathering effect. A monocrystalline diamond tool driven by the designed positive drive mechanism facilitates scraping at a highfrequency using positively reciprocated motion. To inhibit system vibration caused by a single crankshaft, a dual-crankshaft out-of-phase balanced drive mechanism is developed, which allows both the primary drive shaft and balance shaft to possess identical eccentric distance with their eccentric forces going in opposite directions. The design off sets the eccentric force made by revolution of the primary drive shaft against the simultaneous force made by the revolving balance shaft. Experiments show that when system vibration error is restrained to 1-μm, the single crankshaft tool reaches a drive frequency of 15 Hz. While under the dual-crankshaft out-of-phase setup, drive frequency reached up to 50 Hz. Further experimental results demonstrated that the dual-crankshaft out-of-phase balanced drive mechanism has the capability of scraping a vast microconcavity pattern with high-precision, -integrity and -consistency. Characteristic surface roughness of microcavities was below Ra 0.024 μm and feature edges were burr-free. In addition, this paper discusses in detail: the material shear rate, scraping force prediction, influences of the workpiece forward feed-rate and tool actuation frequency as well as the relationship between major and minor axes in microconcavity formation.
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Shun-Tong Chen,Kuo-En Chang,Wei-Ping Huang,Hong-Ye Yang,Xiu-Mao Lee 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.
This study presents the development of a cost-effective high-precision bench machine tool prototype for machining multi-level micro aspheric lighting-lens molds. To achieve high-precision over a long lifetime of micromachining, the bench machine tool is designed using a small C-shaped framework to strengthen static rigidity and vibration resistance. The primary structures of the machine tool are constructed with tempered nodular graphite cast iron to obtain a high damping coefficient and high inherent resonant frequency. A multi-level aspheric curve generator is designed according to the multi-level aspheric curve equation to easily create an aspheric curve and then rotated into an aspheric surface form with a symmetrical optical axis. The verifications of the designed bench machine tool’s functions were conducted by machining the micro aspheric lighting-lens molds using highspeed micro milling. Experimental results demonstrate that form accuracy and surface roughness for the micro aspheric lightinglens mold of Rt 2.937 μm and Ra equal to 0.032 μm respectively could be simultaneously achieved. The developed cost-effective bench machine tool can supply high-quality and fast machining in the fabrication of micro optoelectronic molds such as those used for micro aspheric lighting-lenses.
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Shun-Tong Chen,Li-Wen Huang 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.5
Diamond is a typical super-hard material with very high thermal conductivity. This makes is highly suited to heat dissipation from electronic microchips. The stability of its chemical lattice structure, however, means it has no free-electrons and a high melting point, making machining of diamond difficult. In this study, a micro-energy w-EDM (wire-Electric Discharge Machining) power source with dual-capacitance is designed for using high-frequency spark erosion to precisely cut borondoped nano-polycrystalline diamond (B-NPD) material. The power source design consists of a dual-capacitance circuit, a programmable logic circuit (PLC), and a metal–oxide–semiconductor field-effect transistor (MOSFET). By utilizing a high-frequency switching dual-capacitance circuit, each capacitor has enough charge/discharge time to create a micro-energy pulse train of uniform iso-pulse on-time (τ on ) and iso-pulse peak current (I p ). Material removal occurs rapidly so that microquantities of diamond are readily removed to reduce the probability of thermal damage and graphitization. The technique allowed successful machining of a highly consistent plate-finned diamond heat-sink array and trapezoid-pillar diamond heat-sink array. Furthermore, manufacturing using the designed low-energy power-source is highly efficient. To estimate machining efficiency in terms of the content of charge per unit volume per unit of time in diamond cutting, “Charge Density (CD)” is proposed and examined as an evaluation criterion. The following are all discussed in detail: work frequency, work capacitance, wire-electrode number and short-circuiting percentage, heat-erosion on fi ns of different thicknesses, and fi n efficiency.
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Shun-Tong Chen,Shih-Yao Chen 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.6
A high-frequency discharge power source with non-equal energy relaxation oscillator circuit is proposed in this study. An experiment based on gallium oxide (Ga2O3) and an aluminum alloy microstructure array is devised to verify the machining performance of the power source. Signals are sent by a field-programmable gate array (FPGA) for the control of an N-MOSFET load switch, thus determining when the power source charged and discharged to generate a discharge waveform with narrow pule width and alternating high and low peaks. Compared to a conventional RC discharge circuit, the proposed design generated a pulse train with a regular and dense pattern and created high-density and tiny-energy high-temperature plasma. The experiment was performed with a high-frequency discharge energy pulse train designed with alternating high and low-peaks to examine the machining performance of the discharge source for pyrolytic Ga2O3 material including: the best-fit capacitance combination, feed-rate of wire-electrode, material removal rate, kerf width and spark erosion capability. The experiment’s results revealed that the design high-frequency relaxation oscillator circuit successfully generated surface microstructure arrays and pillared microstructure with outstanding dimensional accuracy and consistence. Clearly, the application of the proposed high-frequency power source proposed performed admirably in spark erosion in addition to its high-efficiency, -controllability, and -stability, and it prevented thermal damage to microstructures. The workpiece’s polarity, surface roughness, material removal mechanism, surface degenerating layer and discharging performance of metal and semiconductor are analyzed both quatitatively and qualitatively.
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