• Korean Chemical Engineering Research
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• 제56권2호
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• pp.191-203
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• 2018

이 연구는 각각 크기와 재질이 다른 3 가지 종류의 분쇄 매체를 이용하여 회전속도와 밀링 시간의 따른 구리 (Cu) 분말의 형상변화의 과정에 미치는 영향을 관찰하고, 볼 움직임의 DEM시뮬레이션을 행하였다. 전동볼밀에서 볼 움직임의 3차원 시뮬레이션을 통해 분쇄 메커니즘을 규명하기 위하여 분쇄매체의 힘, 운동에너지, 매체 운동속도 등을 계산하였다. 시뮬레이션에서는 회전속도, 볼 재질, 운동속도, 마찰계수 등을 실제 실험조건과 동일하게 조건을 맞추어 투입되는 에너지의 변화량도 계산하였다. 주사전자현미경 결과를 살펴보면 볼 직경이 작을 때 입자형상이 불규칙한 형태에서 구형 형태로 변화하는 것을 알 수 있었다.

• 한국공작기계학회논문집
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• 제15권5호
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• pp.79-84
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• 2006

In modem manufacturing, many products that have geometrically complicated features, including three-dimensional sculptured surfaces, are designed and produced. In the production of these complex-shaped mechanical components, e.g. automobile dies, molds, and various engineering applications, the ball-end milling process is one of the most widely used NC machining processes that consists of roughing, semi-finishing and finishing. In semi-finishing, cusps remained after roughing according to the used tools that have two patterns of stairs and wave shapes. These cusp shapes have air-cut in cutting and instability caused by high cutting speed that affects the cutting characteristics such as cutting force and tool wear. Cutting characteristics are measured and analyzed through cutting force, FFT analysis of cutting force and tool wear along cutting length according to low tool paths with same metal removal rate. As a results of the experiments, this study suggests the optimal conditions of tool path and cutting direction. This approach for the cutting characteristics of semi-finishing provides a useful aid for the productivity and efficiency improvements of NC machining processes.

• 산업공학
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• 제18권3호
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• pp.247-252
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• 2005

In the automated production environment in the present days, the minimization of manual operation becomes a very important factor in increasing the efficiency of the production system. The exit burr produced through the milling operation on the edge of workpiece usually requires manual deburring process to enhance the level of precision of the resulting product. So far, researchers have developed various methods to understand the formation of exit burr in cutting process. One method to analytically identify the formation of exit burr was to use the geometrical information of CAD and CAM data used in automated machining. This method, in turn, generated the information resulting from the analysis such as burr type, cutting region, and exit angle. Up to now, the geometrical data were restricted to the single feature and single path. In this paper, a method to deal with the complicated geometric features such as line segment, arc, hole, and spline will be presented and validated using the field data. This method also deals with the complex workpiece shape which is a combination of multiple features. As for the cutting path, multiple tool path is analyzed in order to simulate the real cutting process. All this analysis is combined into a Windows based software and real data are used to validate the program in the conclusion.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.336-337
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• 2005

This study shows the effect of addition of $LiCoO_2$, with different milling time ranging from 0, 30, 200 hours, to the activated carbon electrode. Test cells consisting of activated carbon (100-X%) and $LiCoO_2$ (X%)were made (where X=10, 20, and 40). Test cells with varying concentrations of $LiCoO_2$ which differ in the milling time showed improved specific capacity compare with the cells fabricated using activated carbon alone. The enhanced capacity may be caused due to the addition of $LiCoO_2$ powders at varying concentration. An improved ESR value obtained may be caused by the smaller particle size of $LiCoO_2$. It was concluded that finer the particle size higher will be the efficiency.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.1044-1048
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• 1997

Wire-cut EDM is used in Die manufacturing as the part of non-traditional cutting process, But,the determination of it's cutting condition with high efficiency and precision is difficult due to the influence of cutting environment and cutting mechanism. In this study, we examine the cutting performance of the SKD11 and Brass in wire-cut EDM and make the neural network which have the configuration of 5-12-2 and back-propagation learning rule. Through the neural network, we can appraise the cutting performance before working and determine the optimal cutting condition. By introducing this method to the W-cut EDM, we can enhance the cutting efficiency.

• 한국공작기계학회논문집
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• 제10권5호
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• pp.17-24
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• 2001

Recently, the requirements for high precision and efficiency machining are gradually increased to raise international competitiveness at the industrial fields of die and molds. This trend had made effects on the industrial fields in Korea and which needs fur studying of high precision and efficiency machining. This study is to investigate the effects of the non-out of end mill in the external cylindrical machining operated by solid carbide end mills with Al-alloy in high speed machining center relating to high spindle revolution and frost fred per minute on the dimensional precision, roundness of workpiece. From the results of experimentations followings are obtained; when Al-alloy is processed by the external cylindrical cutting of end milling through the high speed revolution, if the spindle revolution is higher relating to radial depth of cut, feed per tooth in very lower situation, finally, productivity can be raised because high precision and quality products are machined high efficiently.

• 한국CDE학회논문집
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• 제11권6호
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• pp.422-428
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• 2006

In this paper, an NC data optimization approach for enhancing 5-axis machining speed is presented. It is usual to use expensive commercial CAD/CAM programs for NC data of 5-axis machining, since it needs very large calculations for optimal tool positioning and orientation, tool path planning, and collision-free tool path generation. Since commercial CAD/CAM systems have similar functions and efficiency based on common algorithms of reliable theories, they do not have their own unique features for machining speed and efficiency. In other words, most commercial CAD/CAM systems consider only the characteristics of part geometry to be machined, which means that they generate almost the same NC data if the part to be machined is the same, even though different machines are used for the pin. A new approach is proposed for optimizing NC data of 5-axis machining, which is based on the characteristics of the machine to be operated. As a result, the speed of 5-axis machining can increase without losing machining accuracy and surface quality.

• 한국세라믹학회지
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• 제40권7호
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• pp.696-701
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• 2003

교반형 볼 밀에서 실리카 분말의 열처리에 따른 분쇄효율을 분쇄에 따른 에너지 소비량을 측정함으로써 조사하였다. 열처리를 행한 것과 행하지 않은 시료를 비교해 보면, 600~90$0^{\circ}C$에서 열처리 후 실온에서 냉각된 시료를 건식 분쇄하였을 경우 약 40~50% 정도, 열처리 후 물속에서 급속 냉각한 경우 약 52～62% 정도의 에너지의 감소 효과가 있었다. 또한 열처리한 실리카 분말을 습식 분쇄를 할 경우 건식 분쇄에 비하여 약 40% 정도의 분쇄에너지가 적게 소모되고 있음을 알 수 있었다. 또한 실리카 분말을 열처리 한 후, 급속 냉각할 경우 발생하는 열충격은 입도에 대한 영향을 거의 받지 않으며 분쇄효과를 향상시킴을 알 수 있었다.

• 한국정밀공학회지
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• 제13권6호
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• pp.59-65
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• 1996

There are many difficulties in automatic polishing for die & mold surfaces. Even though the process has been studied in the past 15 years, it has not been achieved yet, but by the process of actual hand work of well-skilled workers. A new magentic assisted polishing process, which is one of the potential methods for automation of surface finishing has been studied in the past 10 years by colleagues. The process has many merits, but on the other hand also has demerits, one being low efficiency of grindability by comparision with wheel polish. Therefore, some attempts were tried to improve the grindability by adopting electropolishing, ultra-high speed milling, 5-axis controlled machine etc... most recently by colleagues. This paper also aims to improve the efficiency of polishing by introducing the easily-polished shape surface cutting method equalizing the tool feed per revolution to the pick feed. This cutting method was experimentally confirmed to have sufficient grindability to polish milled surface (with $10{{\mu}m}$Rmax surface roughness) into mirror surface (with $0.4{{\mu}m}$Rmax surface roughness).

• Journal of Biosystems Engineering
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• 제20권1호
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• pp.47-57
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• 1995

Rice Processing Complex(RPC) have being constructed with a rice mill plant and a facility of drying and storage to overcome problems caused by UR and to produce good quality of rice. An optimal design of a rice mill plant was required to successfully construct and operate it. The development of a simulation model was essential to the design of a rice mill plant. So, all the objectives of this study were to develop a simulation model for the design of a rice mill plant and to develop and evaluate the rice mill system. In this study the simulation model was developed to design a rice mill plant using SLAMSYSTEM, one of simulation languages. The results of this study were as followings. 1. A simulation model was developed with SLAMSYSTEM to represent the processes of a rice mill plant. The simulation model was used to design a rice mill pilot plant with the capacity of 0.5 ton per hour. The rice mill pilot plant was analyzed by the model with alternatives. 2. In the simulation the rice mill system was much influenced by the separating efficiency of a brown rice separator. Especially, the bottleneck of grain flow occurred at the buffer tank for brown rica. separator under 50% separating efficiency of brown rice separator. Hence, as the alternative simulation was conducted under 60% , 70% separating efficiency of brown rice separator, the bottleneck of the system could be minimized at the 60% separating efficiency of brown rice separator. 3. In the alternative simulation the bottleneck of the system was minimized under the hulling capacity of 1 t/h and 60% separating efficiency of brown rice separator with the capacity of 1 t/h. Under such a condition the max. weight of waiting entities at buffer tanks was less 250kg. So, the capacities of the buffer tanks were determined in the basis of simulation results. 4. The milled rice recovery and head rice recovery of the milling system were 74% and 92% in the simulation, respectively. These results of simulation almost corresponded to those of actual rice mill plants. The developed simulation model could be well applied to design a rice mill plant.