• 기술사
• /
• 제30권6호
• /
• pp.144-152
• /
• 1997

Development of diamond wheel with fine grains and multi-pore structures were newely attempted to be studied in this paper. Wheels, that are employed for the smooth and mirrow finishing of die 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 abrasive grains were bonded firmly by a melamine 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 sufaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are explained.

• 한국정밀공학회지
• /
• 제15권6호
• /
• pp.153-158
• /
• 1998

In this paper, a theoretical analysis is presented on the mechanics of the grinding by hemispheric type electroplated CBN wheel. The grinding forces acting on a single grain were calculated from its geometry by assuming the abrasive grain is spherical. Then. the total grinding forces were obtained by estimating the number of acting abrasive grains and the area of contact. The model includes the grinding variables such as wheel speed. feed speed. depth of cut, and grinding wheel positions. Experiments were also carried out to compare with the analytical results. The experimental results were found to be in good agreement with the analytical ones.

• 한국생산제조학회지
• /
• 제7권6호
• /
• pp.97-101
• /
• 1998

In this study, The ultra-precision finishing system is applicable to all kind of the cylnderical workpiece products fast and easy. This system was applied to chrome coated steel to investigate the characteristic of grinding; (1) 3$mu extrm{m}$ of abrasive film is not use for grinding performance. (2) Grinding condition of coated chrome steel would set up differently, in 30~12${\mu}{\textrm}{m}$, in 9~5${\mu}{\textrm}{m}$. (3) The surface roughness of chrome coated steel was about Ra 0.0009${\mu}{\textrm}{m}$ in abrasive grain size 5${\mu}{\textrm}{m}$.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 춘계학술대회 논문집
• /
• pp.599-602
• /
• 2000

A new dressing technique with utilizes electrolytic phenomenon for realizing effective mirror surface grindings with metal bonded super-abrasive wheels is called “Electrolytic In-process Dressing Grinding”. This technique enabled metal bonded micro-grain wheels, such as micro-grain cast iron fiber bonded wheels, to be used for mirror surface finish processes effectively. But this technique requires a lot of knowledge and experience to perform. And the condition of dressing is variable according to the time. Therefore adaptation of Monitoring and Control technique is needed.

• Journal of Biosystems Engineering
• /
• 제12권1호
• /
• pp.20-30
• /
• 1987

Major rice grain losses both in quality and in quantity are incurred in the whitening process which is indispensable in the milling process. Rice whitening it performed by two different whitening actions known as abrasive and frictional. In Korea, abrasive-type whiteners equipped with a emery-stone roller have been adopted in the whitening system in large scale milling plants, but not in customary small scale. However, researches on this type whitener have rarely been conducted in Korea. This study was attempted to establish design criteria or a modified abrasive-type whitener which is aerated with blower. The factors considered in this study were three levels of feedscrew pitch (20, 27, 34 mm) and three levels of clearance(11, 13, 15 mm) between surfaces or emery-stone roller and screen and two levels of moisture content (14.5%, 15.7%, w.b.) of brown rice. Also, the effect of aeration on whitening performance was examined, and a system performance consisting of one pass in the aerated abrasive-type and two passes in the existing friction type was compared with the performance of the existing whitening system consisting of three passes in friction type only. The latter system is prevailed in customery small milling plants. The results of this study are summarized as follows. 1. The interactions between feed-screw pitch and chamber clearance of the aerated abrasive-type whitener had great effect on the performance of the machine. When the value of a nondimensional parameter, $C^2/(P{\cdot}d_p)$, expressing the relations between feed-screw pitch, P, and chamber clearance, C, ranged from 0.40 to 0.45, the performance of the aerated abrasive-type whitener was the best. 2. Aeration to the abrasive-type whitener gave positive effect on milled and head rice recoveries. 3. The whitening system involving the aerated abrasive-type whitener, which has appropriate feed-screw pitch and chamber clearance as described in item 1 above, produced more milled and head rice recoveries by about 1.5% and 2.0%, respectively, than the existing frictional whitening system. The former also consumed less electricity by about 10% (0.9KwH/1000kg).

• 한국정밀공학회지
• /
• 제22권10호
• /
• pp.39-48
• /
• 2005

As the industrial development is accelerated, a new machining process and system are keenly required to achieve super precision surface finish. Especially to get ground surface finish fer complicated and narrow inner shape of molds, it is impossible with the existing methods so that a new method is being required to be developed. A new material, called Magic(MAGnetic Intelligent Compounds), is finally made and it is called Magic machining that uses this material. There is a way to make a material as follows, the mixture of magnetic particles, bonding material and particles of abrasive grain should be melt down by proper heat, and then this mixture put in a mold and cool down in magnetic field which has a uniform direction. This new polishing method is spotlighted as an excellent solution to the existing problems. However it hasn't reported any study about the influence of the machining conditions of polishing velocity, amplitude and polishing pressure to the surface roughness yet. This study would examine closely the influence of polishing conditions of the Magic polishing tool to the surface finish to decide the optimum polishing condition and to standardize the Magic polishing work.

• 한국생산제조학회지
• /
• 제19권4호
• /
• pp.491-497
• /
• 2010

The magnetic polishing is the useful method to finish some machinery fabrications by using magnetic power. This method is one of the precision techniques and has an aim for clean technology in the clean pipes. The magnetic abrasive polishing method is not so common in the field of machine that it is not known to widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. This paper deals with mediocritizing magnetic polishing device into regular lathe and this experiment was conducted in order to get the best surface roughness at low cost. This paper contains the result of experiment to acquire the best surface roughness, not using the high-cost polishing material in processing. In this paper, We could have investigated into the changes of the movement of magnetic abrasive grain. In reference to this result, we could have made the experiment which is set under the condition of the magnetic flux density, polishing velocity according to the form of magnetic brush.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
• /
• pp.355-359
• /
• 2001

In this study, experiments were carried out to investigate the characteristics of grinding and wear process of diamond wheel grinding ceramic materials. Normal component of grinding resistance of $AI_2O_3$ was less then that of $Si_3N_4$ and $ZrO_2$. It is because the resistance for grain shedding is less then that for layer formation. For the case of $Si_3N_4$ and $ZrO_2$, as the grain mesh number of wheel increases, the surface roughness decreases. For the case of $AI_2O_3$, the surface roughness does not decreases. For the case of $Si_3N_4$ and $ZrO_2$, grinding is carried out by abrasive wear processes. For the case of $AI_2O_3$, grinding is carried out by grain shedding process.

• 한국공작기계학회논문집
• /
• 제15권1호
• /
• pp.119-126
• /
• 2006

The finishing process of die requires the processing technique of a height efficiency and precision. Because the precision of die gives the quality of goods the influence directly. The hydro-static polishing device employs the hydro-static axis and is able to polish the structure of complex picture under the constant pressure and is got constant surface roughness at all polished plane. Therefore, In order to polish precision sculptured surface, it was used the hydro-static polishing device. Polishing device's polishing characteristic is estimated by polishing conditions which are size of abrasive, material of tools. And, because the surface quality of workpiece depends on polishing pattern which relates to motion of abrasive grain. The polishing characteristic according to polishing pattern was evaluated.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1994년도 추계학술대회 논문집
• /
• pp.113-118
• /
• 1994

An experimental investigation on the wear of alumina grinding wheel is presented. The experiments consist of the measurements of fracture strength of the abrasive grains, grinding forces, and the area of wear flats of grinding wheels. Microscopic examinations of abrasive grains were also carried out to observe the progress of wheel wear. the results show that the 32A grain, which has relatively lower fracture strength, wears out faster than 5SS and 5SG. The wheel wear occurs much faster in wet grinding than in dry grinding. It has also been found that the grinding forces increase logarithmically with increasing wear flats.