• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.441-446
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• 2000

Although the net-shape molding of composites is generally recommended, molded composites 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 grinding area 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 grinding point during surface grinding of carbon fiber epoxy composite was measured. The grinding temperature and surface roughness were also measured to investigate the surface grinding characteristics of the composited. The experiments were performed both under dry and wet grinding conditions with respect to cutting speed, feed speed, depth of cut and stacking angle. From the experimental investigation, the optimal conditions for the composite plain grinding were suggested.

• 한국정밀공학회지
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• 제13권12호
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• pp.38-45
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• 1996

A new grinding wheel was developed for the high performance grinding of difficult-to-grinding materials. The grinding performance of the newly developed wheel including grinding forces, grinding ratio, and surface roughness of ground surface was evaluated through experiments. Experimental results show that the performance of the newly developed wheel is superior to the conventional alumina wheel and comparable to the Sol-gel wheel. An experimental investigation on the wear of alumina grinding wheel was also carried out. The experiments consist of the measurements of fracture strength of the abrasive grains, grinding force, and the area of wear flats of grinding wheels. Microscopic examination of abrasive grains was executed to observe the progress of wheel wear. The results indicate 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.

• 한국재료학회지
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• 제23권2호
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• pp.89-97
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• 2013

The study of grinding behavior characteristics on aluminum powders and carbon nano tubes (CNTs) has recently gained scientific interest due to their useful effect in enhancing advanced nano materials and components, which significantly improves the property of new mechatronics integrated materials and components. We performed a series of dry grinding experiments using a planetary ball mill to systematically investigate the grinding behavior during Al/CNTs nano composite fabrication. This study focused on a comparative study of the various experimental conditions at several variations of rotation speeds, grinding time and with and without CNTs. The results were monitored for the particle size distribution, median diameter, crystal structure from XRD pattern and particle morphology at a given grinding time. It was observed that pure aluminum powders agglomerated with low rotation speed and completely enhanced powder agglomeration. However, Al/CNTs composites were achieved at maximum experiment conditions (350 rpm, 60 min.) of this study by a mechanical alloy process for Al/CNTs mixed powders because the grinding behavior of Al/CNTs composite powder was affected by addition of CNTs. Indeed, the powder morphology and crystal size of the composite powders changed more by an increase of grinding time and rotation speed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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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.

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

• 한국재료학회지
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• 제25권6호
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• pp.305-316
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• 2015

The study of grinding behavior characteristics on the metal powders has recently gained scientific interest due to their useful applications to enhance advanced nano materials and components. This could significantly improve the property of new mechatronics integrated materials and components. So, a new evaluation method for standardizing grinding equipment and a comparative study for the grinding experiment during the grinding process with various grinding mills were investigated. The series of grinding experiments were carried out by a traditional ball mill, stirred ball mill, and planetary ball mill with various experimental conditions. The relationship between the standardization of equipment and experimental results showed very significant conclusions. Furthermore, the comparative study on the grinding experiment, which investigated changes in particle size, particle morphology, and crystal structure of materials with changes in experimental conditions for grinding equipment, found that the value of particle size distribution is related to the various experimental conditions as a revolution speed of grinding mill and media size.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.793-797
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• 2000

The environmental problems by using coolant demanded the new cooling methods. As one of them the studies on the dry grinding with compressed cold air have been done. The cooling method using compressed cold air was effdve thmugh going down the temperature of compressed air supplied below $-25^{\circ}C$ and inneasing the amount of mmpresd cold air, but had not enough cooling effect due to the low performance of lubrication. Therefore, the cooling methods using MQL(Minimum Quantity Lubrication) or mist newly were suggested. These two methods can satisfy both cooling effect and lubrication with only small amount of coolant, also has the benefit in the point of decreasing the envimnmental pollution. This paper focused on analyzing the grindmg characteristics of the cooling method using mid. The generated heat and grinding force of the cooling method using mist were compared with them of coolant and compressed cold air. And them grinding test according to the temperature of compressed cold air, mist spray amount and mist supply direction were done.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.469-471
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• 2001

Dry grinding of a mixture of CaCO$_3$ and Ca(H$_2$PO$_4$)$_2$.$H_2O$ was conducted using a planetary ball mill in order to investigate solid state reaction for a synthesis of hydroxyapatite(Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$, HAp) through mechanochemical treatment method. The raw materials, which are composed of waste oyster and calcium biphosphate Ca(H$_2$PO$_4$)$_2$.$H_2O$, were mixed and then treated mechanochemically. The synthesis of hydroxyapatite(Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$, HAp) from the mixture was almost completed by about 60 minute grinding. The formation of HAp monophase in the ground mixture was characterized through X-ray diffraction (XRD) analysis. Moreover, the formation of HAp monophase depending on the grinding time was improved by increasing the grinding time.ime.ime.

• 한국식품영양과학회지
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• 제41권11호
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• pp.1596-1602
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• 2012

국내에서 육종된 8가지 품종의 쌀을 습식과 건식제분하여 제분 방법에 따른 쌀가루의 품질변화를 품종별로 분석하고 이를 바탕으로 제분 방법에 비교적 민감하지 않고 일정한 품질의 가루를 생산할 수 있는 국내산 쌀 품종을 찾고자 하였다. 건식제분은 예상한 바와 같이 낟알의 경도가 높은 품종이 전분 손상도가 높았으나 습식제분에서는 Chenmaai와 같이 불린 쌀의 경도가 높더라도 전분의 손상도는 상대적으로 낮았다. 건식제분에 따른 손상 전분 함량의 증가는 쌀가루의 수분 흡수력을 급격히 증가시켰으며 습식제분은 낟알의 경도보다는 아밀로오스 함량에 따라서 수분 흡수력에 차이를 나타내었다. 가루의 수분 흡수력과 반비례하여 반죽의 질척한 정도가 나타나지만 고 아밀로오스 함량의 Suweon 517과 Milyang261은 제분 방법에 관계없이 수분 흡수력이 매우 높아서 빵이나 국수 등의 제품을 생산할 때 반죽에 더 많은 양의 물을 첨가해야 할 것으로 생각된다. 또한 건식제분된 가루가 습식제분된 가루에 비하여 수분 흡수력이 크기 때문에 반죽 과정에서 수분 첨가량을 증가시켜야 할 것이다. 건식제분은 품종 모두에서 최고 점도에 이르는 시간이 짧아지고 점도 붕괴가 증가하므로 습식 가루에 비하여 조리시간을 단축하고 호화 후 점도 조절이 필요하다. Hanareumbyeo, Manmibyeo, J insumi, Goamibyeo 등은 건식제분과 습식제분에 따른 호화 특성의 변화가 다른 품종에 비하여 크며, Suweon517과 Milyang261은 건식제분하면 setback 값이 증가하는 것으로 미루어 건식제분된 가루를 이용한 제품의 노화가 더 클 것으로 예측된다. 이상의 결과에 따라서 Chenmaai는 건식과 습식제분 모두에서 손상 전분의 함량이 낮고, 건식제분에 따른 수분 흡수율 증가가 적으며 제분에 따른 호화 점도 특성의 변화가 상대적으로 적어서 제분에 유리한 품종이다. 반면 Seolgaeng와 Suweon517은 낟알의 경도가 부드러운 분상질일지라도 건식과 습식제분 모두에서 손상전분 함량이 높고 수분 흡수력과 호화 점도의 특성 변화가 심하여 쌀가루로 분쇄하는 제분 적성이 좋지 않았다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.950-955
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• 2003

Recently, emerging as major tasks are grobal warming prevention, and earth environment conservation and preservation, and the resolution of environmental issues is crucial in the 21st century and needs to jointly be tackled by all nations in cooperation with each other. This research developed dry cold air grinding system, and this ensured cold effects of machine tools and dressing effects against loading phenomenon of grinding wheel, thus extending the tool life of grinding wheel.