• Design & Manufacturing
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• v.11 no.1
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• pp.1-6
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• 2017

In these days, due to generalization of using smart mobile phone and wearable device such as smart watch, demand of Cover-glass and touch screen panel for protecting display increases. With increasing the demand of Cover-glass, slimming technique is promising for weight lightening, zero bezel. Cover-glass produced by this technique is required to decreasing thickness with increase strength. In the Cover-glass manufacturing process, mechanical processing and chemical processing has improve in the strength. Generally, Diamond electrodeposition wheel is used in mechanical process. Reinforced glass with the characteristics of the brittle and high hardness was manufactured by using a diamond electrodeposition wheel. At this time, Because of surface of the tool present non-uniform distribution of diamond particle, it has generate Loading of wheel and it has been decrease life of grinding tool, efficiency of grinding, quality and shape accuracy of workpiece. Thus Research is needed to controling particle distribution of diamond electrodeposition wheel uniformly. And it is necessary to study micro hole machining such as proximity senser hole, speaker hole positioned Cover-glass. Reinforced glass with the characteristics of the brittle and high hardness is difficult to machining. Processing of reinforced glass have generated wear of tool, micro cracks. Also, it is decreasing shape accuracy. In this paper, We conducted a study on how to control particle distribution uniformly about the diamond tool manufactured using elecetodeposition processing. It analyzed the factors that affect the arrangement of the particles in the electrodeposition process by design of experiment. And There is produced the grinding tool, which derives an optimum deposition conditions, for processing Cover-glass edge and the machinability was evaluated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2172-2178
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• 1997

Development of diamond wheel with fine grains and multi-pore structures were newely attempted. Wheels, that are employed for ultra precision and high performance grinding of difficult-to materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond grains were bonded firmly by a melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work surfaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are suggested, and the grinding characteristics of wheels are also illustrated.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.694-700
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• 2011

Since polycrystalline diamond (PCD) has high hardness like diamond, it has been used as tool material for lathe and milling of non-ferrite material. A micro tool fabricated from PCD material can be used for micro machining of hard material such as tungsten carbide, glass, and ceramics. In this paper, micro PCD tools were fabricated by micro EDM (electrical discharge machining) and used for micro grinding of glass. Craters generated on the tool surface by EDM spark work as like grits in grinding process. The effects of tool shapes, tool roughness and PCD grain size were investigated. Also studied was a hybrid process combining electrochemical discharge machining (ECDM) and micro grinding for micro-structuring of glass.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.19-24
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• 1998

This paper aims to clarify the effects of grinding conditions on the ground surface and bending strength in surface grinding of various ferrites with diamond wheel. The main conclusions obtained were as follows. The surface roughness becomes better at lower wheel speed in the case of v/V=1$\times$10-3, and the condition of v/V=1$\times$10-4shows the best performance for the finish grinding. When the relative contact temperature becomes lower at a constant value of v/V, the ground surface exhibits lower roughness. The ground surface shows that the fracture process during grinding becomes more brittle at the higher value of v/V. The damage depth which affect the bending strength is below 10$\mu$m in the grinding condition of S=10㎣/mm.s with the diamond tool after dressing & truing, however, the depth increases with increasing removal rate(S). When the strength degradation due to grinding is larger, the removal depth for the recovery of strength requires a larger size.

• 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.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.8-14
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• 2003

The characteristics of grinding and wear behavior of diamond wheel for grinding ceramic materials was investigated in this study. In case of $Si_3N_4$, the wear of wheel was large, the finding force was relatively stable and the fluctuation of surface roughness n small. On the other hand in case of $Al_2O_3$ and $ZrO_2$, the wear of wheel and surface roughness were decreasing, the grinding force was increasing. During grinding with vitrified bond wheel, $Si_3N_4$ shows renewal of cutting edge while $Al_2O_3$ and $ZrO_2$ show glazing phenomenon of cutting grains. We have found that it possible to observe the behavior of grinding wheel by grinding ratio, grinding resistance, surface roughness and cutting edge ratio. Through the grinding experiments, it was found that grinding life of diamond wheel is 20 times for $Si_3N_4$, and 40 times fir $Al_2O_3$ and $ZrO_2$.

• 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.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.465-470
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• 2000

This paper is concerned with the surface roughness and the bending strength of ground workpiece in ZrO2 ceramic grinding. Surface roughness was measured with surface tracer and bending strength value was obtained by three-point bending test on machining center using tool dynamometer. Grinding experiments were carried out to examine the effects of grinding conditions including diamond mesh size, table speed, and depth of cut on ground surface roughness. The correlation between surface roughness and bending strength was also inspected. The experimental results indicate that the rougher surface was produced as the mesh size of diamond wheel is reduced and table speed is increased, but surface roughness is not affected by depth of cut. The values of bending strength decrease as the values of Ra, Rmax and Ku increase.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.26-26
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• 2003

During fabrication process for the large space optical surfaces, the traditional bound abrasive grinding with bronze bond cupped diamond wheel tools leaves the machine marks and the subsurface damage to be removed by subsequent loose abrasive lapping. We explored a new grinding technique for efficient quantitative control of precision CNC grinding for space optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and a range of resin bond diamond tools. The machining parameters such as grit number, tool rotation speed, work-piece rotation speed, depth of cut 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 methods. The effectiveness of the grinding prediction model 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 details, the results and implications are presented.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.4
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• pp.75-81
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• 2002

In this study, experiments were carried out to investigate the characteristics of grinding and wear process of diamond wheel during grinding ceramic materials. Normal component of grinding resistance was decreasing while increase of spindle speed. The resistance of vitrified bond wheel was less then that of resinoid bond wheel because of imbedded large holes on the surface of cutting edge. Surface roughness was decreasing while increase of spindle speed. The surface roughness using vitrified bond wheel was less than that of resinoid bond wheel because of small elastic deformation. After continuous finding of ceramics, cutting edge ratio of resinoid bond wheel decreased. For the case of vitrified bond wheel, cutting edge ratio did not change.