• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.2
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• pp.31-36
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• 2003

Electronic or measuring instruments equipped with aspherical lens have recently been used since aspherical lens is more effective than spherical one. for the mass production of aspherical lenses, specific molds with precisely machined cores should be prepared. Some researches on the aspherical lens machining have been carried out to date. However, ultra-precise finding of aspherical or mold core has not been fully studied. In this study, the ultra-precise grinding and evaluating system were established to investigate the finding characteristics of aspherical lenses. Unlike conventional grinding process, since a highly-precise lathe were operated in a clean room without vibration the experimental results can be very useful for further studies on ultra-precise grinding process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.938-942
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• 2002

This paper has studied to obtain the grinding characteristics and optimal grinding renditions of ceramic materials in the grinding with diamond wheel by the experimental plan method. The load on wheel by varying the feed rate was related with the surface roughness due to the minute destruction phenomenon of grains for the Si$_3$${N^4} and Zr{O_2}$. The depth of cut is related with the surface roughness because the grinding is carried out by grain shedding process due to the brittle fracture phenomenon for the ${Al_2}{O_3}$. The major factors affecting the surface roughness and the optimum grinding conditions were obtained with minimum experiments using the experimental plan method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.1
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• pp.52-59
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• 1999

An experimental study on the grinding temperature, surface roughness and Acoustic Emission(AE) signals was conducted with different shapes of wheel. The grinding characteristics for slotted shapes of wheel changed by width and helical angle, were compared with those by general one. Lower grinding temperature was obtained for 30$^{\circ}$helical angle with 10mm width and Root Mean square(RMS) values of AE signals were lower for slotted shapes rather than general one. Surface roughness characteristics of slotted shapes found to be rough but the value of roughness for 45$^{\circ}$helical angel with 6mm width, represented to similar tendency general one.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.507-512
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• 1999

In modern engineering practice, the grinding process is one of the most important and widely used operations for the precision finishing of components. In this paper, machining characteristics of external plunge grinding were investigated by using spindle motor current signal through hall sensor. Grinding experiments were performed in terms of various grinding conditions such as wheel speed, workpiece speed, infeed rate and spark-out time with conventional vitrified bonded WA wheel. The relationship between spindle motor current signal and metal removal rate in terms of infeed rate was induced the by analyzing spindle motor current signal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.559-560
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• 2006

Fiber optic connector, ferrule, is a device to connect and align fiber optics cable on fiber-optic communication system. In general $ZrO_2$ ceramic ferrule is manufactured by grinding process because the demands precision is very high. For the precision grinding machining, it is very important that structure of co-axial ferrule grinding system is optimized. In this paper, Structural analysis was performed to analyze bed and frame structure of co-axial grinding machine. Deformation and modal analysis for natural frequency was performed using ANSYS design space program to analyze structural characteristics. New improved model of bed and frame structure was proposed based on initial basic model. Therefore, we estimated the structural characteristics precision co-axial grinding machining system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.338-346
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• 2000

Although the net-shape molding of composites is generally recommended, molded composites are frequently required cutting or grinding due to the dimensional inaccuracy for precision machine elements . During the composite machining operations such as cutting and grinding, the temperature at the cutting point may increase beyond the allowed limit due to the low thermal conductivity of composites, which might degrade the matrix of composite. Therefore, in this work, the temperature at the cutting point during cut-off grinding of carbon fiber epoxy composites was measured. The cutting force and surface roughness were also measured to investigate the cut-off grinding characteristics of the composites. The experiments were performed both under dry and wet grinding conditions with respect to cutting speed and feed rate. From the experimental investigation, the optimal conditions for the composite cut-off grinding were suggested.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.870-873
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• 2000

This investigation reports the grinding characteristics of quartz. Grinding experiments were performed at various grinding conditions including wheel mesh, table speed and depth of cut. The grinding forces and specific grinding energies were measured to compare the grindability of quartz with those of structural ceramics such as A1$_2$O$_3$, SiC, Si$_3$N$_4$ and ZrO$_2$. Surface roughness was also measured with tracer and the ground surfaces were observed with SEM. The chip formation energy of quartz was about 6J/㎣, which is quite smaller than those of structural ceramics. Although plastic flows are occured in Si$_3$N$_4$ and ZrO$_2$, micro/macro cracks are occured in ground surface of quartz like in A1$_2$O$_3$ and SiC.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.2
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• pp.9-16
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• 2013

The comparisons of performance characteristics between the super-mirror face grinding machine using variable air pressure developed in this laboratory to grind precisely the sliding face of a surface hardened workpiece with thermal spray and the conventional one are investigated by measuring the surface roughness and hardness for a SCM440. To process variously workpiece according to shape, size and materials, the rotating and contacting forces of the developed grinding machine can be changed by air pressure. The surface roughness of processed workpiece can be also attained to state of mirror face by grinding precisely the sliding face with changing the rotating speed of diamond wheel. It is possible to be attached to the various machine tools because the super-mirror face grinding machine using variable air pressure is a small size. The grinding efficiency is elevated because it can be worked by two or more grinding machines attached to concurrently a machine tool for the large workpiece. In this study, results show that the cusp height of the super-mirror face grinding machine for the particle size of 100 and $1500No./mm^2$ is lower than that of the conventional one because the vibration is reduced by rotating very fast the diamond wheel with a pressed air and it can be processed by rotating the diamond wheel with a constantly varied air pressure perpendicular to workpiece surface, and that the workpiece in the super-mirror face grinding machine for the particle size of $3000No./mm^2$ can be processed to state of mirror face that is rarely seen by the cusp height. It is also found that the surface hardness of both the conventional and the super-mirror face grinding machines are increased as the particle size of diamond wheel is reduced, and the surface hardness of the super-mirror face grinding machine is HRC 1.1 ~ 1.8 higher than that of the conventional one.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.127-132
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• 2000

A highly efficient mirror surface grinding technology has been developed for hard and brittle materials various metal materials, by employing the ELID (electrolytic in-process dressing) grinding method using metal bonded grinding wheels. In this research, some typical applications of ELID-grinding for cylindrical grinding are introduced and the mirror grinding characteristics are investigated. Good results are obtained in the grinding of ceramics and tungsten carbide.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1109-1112
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• 2001

In the grinding process, the edge of shape is very important to evaluate the surface roughness and the precision of dimension. To keep precision of product, parameters with respect to the amount of wheel wear have to limit by grinding condition. In this paper, we measured variation of grinding force to seek the grinding characteristics by the amount of wheel wear in surface grinding. Also, we find out that how these condition give influence to wheel life.