• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.107-115
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• 2011

Purpose: To design and fabricate the distributed auto edging machine for the development. Methods: We got the necessary data needed in design by using CAD. Based on the these data, we fabricated the trial product for the development of the distributed auto edging machine. Results: The patternless mode could be operated by receiving the eyesize data from the auto lay-outer with the RS232C transmission system and the pattern mode could be operated by setting the pattern on the left side of the machine. The distributed auto edging machine were composed with combinations of many elements; head, auto arm, pattern clamp and grinding wheels. The head part controlled the grinding of ophthalmic lens by operating the vertical and horizontal motors. The wheels part was comprised of glass mode, plastic mode, V-bevel mode and polish mode. The slide in the auto arm was equipped on the below of the patten and the slide could hold up the pattern which was rotated by fixed shaft. The pattern clamp could move the head part to the up and down or right or left way by the manual operation of optometrists. Conclusions: We could succeed in making the trial product by applying it to the development of the distributed auto edging machine which could be used as the patternless mode and pattern mode, selectively. Therefore, it was confidently expected that this product was very helpful for the optometrists to dispense the ophthalmic lens because of its cost-efficiency and convenience.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.1
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• pp.33-38
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• 2006

Silicon has been widely used in electronic parts as a semiconductor equipment. It, however, requires much effort to grind without microcrack and chipping because of its high hardness and brittleness. So far, many studies for the grinding of engineering ceramics have been done, but not for the grinding of silicon. In this paper, a theoretical analysis on the grinding forces is introduced. Grinding experiments were performed at various grinding conditions including grinding directions (Up grinding and Down grinding), table speeds and depth of cuts. The grinding forces were measured to compare at various grinding conditions. The experimental values agree well with theoretical ones.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.787-792
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• 2000

Ultra-abrasives such as diamond and CBN have used to maintain accuracy and form deviation for superalloy etc. This study contains the dry cylindrical grinding of metals with Vitrified-bond CBN wheel. For various conditions of grinding speed, workpiece speed, grinding depth and feed speed of table, the grinding resistance, the surface roughness, and the material removal are measured and discussed. The results are as follows.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.3
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• pp.105-110
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• 2020

Alumina, a typical ceramic material used for semiconductors and display parts, is the subject of research and development efforts for mineral material processing. Alumina is extremely difficult to process since it is brittleness to either fine ceramics material. We have studied the shape of diamond particles and their use in machinability for alumina processing. Our study was carried out under various processing conditions, including cutting speed, table speed, and the surface roughness of the work piece. We also analyzed the wear characteristics of the tool by total cutting.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.344-349
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• 2005

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 weal 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.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.118-125
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• 1999

In the grinding process, generally, the exciting forces with high frequency can be generated due to the wheel wear and the grinding process. As the grinding speed increases, the precise investigation about the wheel dynamic characteristics is required. Conventionally the wheel-spindle has been considered with lumped model in dynamic modeling. With this lumped model, the significant mode resulted from the shell mode of wheel can be readily ignored. This paper suggests the new analysis model which includes the shell mode of wheel in modeling the wheel-spindle assembly. Furthermore, based on the suggested model, the effects of the bolt tightening force and the taper tightening force on the dynamic properties are investigated by the finite element modal analysis and the experimental method. As a result of investigation, the shell mode vibration of wheel affects the dynamic characteristics of the spindle assembly. Also, the vibration modes of the spindle assembly are significantly affected by the joint tightening forces.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.84-88
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• 2016

This study evaluated the structural safety of a heavy-duty integrated machine for grinding wheel forming. Structural analysis was performed to evaluate the structural safety of the base. The base was designed by dividing the single base and detachable base. The analysis conditions were applied to the own weight and the load of component parts. From the structural analysis results, although the stress of the detachable base was decreased, the amount of deformation was increased. If the deformation of the detachable base decreases, it is expected to be safer than the single base.

• Journal of Astronomy and Space Sciences
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• v.21 no.2
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• pp.141-152
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• 2004

Optics fabrication process for precision space optical parts includes bound abrasive grinding, loose abrasive lapping and polishing. The traditional bound abrasive grinding with bronze bond cupped diamond wheel leaves the machine marks of about $20{mu}m$ rms in height and the subsurface damage of about 1 ${mu}m$ rms in height to be removed by subsequent loose abrasive lapping. We explored an efficient quantitative control of precision CNC grinding. The machining parameters such as grain size, work-piece rotation speed and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis. The effectiveness of such grinding prediction models was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment achieved the predictability down to ${pm}20$ nm in height and the surface roughness down to 36 nm in height. This study contributed to improvement of the process efficiency reaching directly the polishing and figuring process without the need for the loose abrasive lapping stage.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.243-244
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• 2007

본 연구에서는 성형용 코어 가공에서 초경합금(WC, Co 0.5%)의 초정밀 가공특성을 파악하기 위하여 다이아몬드 휠의 메시, 주축 회전속도, 터빈 회전속도, 이송속도 및 연삭깊이에 따른 표면거칠기를 측정하여 최적연삭조건을 규명하였다. 규명된 최적연삭가공조건을 활용하여 페러렐 연삭법으로 초정밀 연삭가공을 수행하였다. 연삭가공은 초정밀가공기(ASP01, Nachi-Fujikoshi Co., Japan)를 사용하였다. 최종 정삭가공을 수행한 비구면 성형용 코어의 형상측정결과 형상정도(PV; ${\varphi}$ 3.0mm) 0.15${\mu}m$(비구면), 0.10${\mu}m$(평면)으로 3M급 이상의 고화질 카메라폰에 채용되고 있는 비구면 Glass렌즈 양산용 성형용 코어 규격에 만족한 결과로서 본 연구에 수행된 초정밀 가공조건 및 측정방법이 매우 유효함을 알 수 있었다. 형상정도(PV) 및 표면조도(Ra) 측정은 초정밀 자유곡면 측정기(UA3P, Panasonic Co., Japan)와 3차원 표면조도 측정기(NewView5000, Zygo Co., USA)를 각각 사용하였다. 초정밀 가공된 성형용 코어면에 이온증착법을 활용하여 DLC 코팅을 수행하였다. 코팅 전후의 성형용코어를 활용하여 Glass소재(K-BK7, Sumita Co., Japan)를 최적의 성형조건(성형온도, 압력, 냉각속도)으로 성형하였다. DLC 코팅과 성형은 DLC 코팅기(NC400, Nanotech Co., Japan)와 Glass렌즈 성형기(Nano Press-S, Sumitomo Co., Japan)을 각각 사용하였다. Fig. 1은 초정밀 연삭가공, DLC 코팅막 구조, 코팅된 성형용 코어, 그리고, 성형된 비구면Glass렌즈를 각각 나타낸다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.2
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• pp.26-32
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• 2010

This paper reports some experimental result in grinding and polishing of silicon cathodes used in semiconductor manufacturing process. Cup shape diamond core wheels were used in experiments and the radial and tangential grinding forces were measured with surface roughness. In polishing experiments, flat type and donut type wool polishing tools were tested. The experimental results indicate that the grinding forces are proportional to the material removal rates and the surface roughness are inversely proportional to the spindle speed. The surface roughness of polished Si decreases with polishing time and higher spindle speed.