• 한국정밀공학회지
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• 제26권1호
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• pp.82-88
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• 2009

Ultra-precision turning is highly needed to manufacture molds for precision lens. In this study, micro-turning combined with elliptical vibration cutting (EVC), which is known to enhance micro- machining quality, was investigated by installing a rotary stage into the micro-grooving machine. From machining experiments involving materials of copper, brass, and aluminum and single and poly crystalline diamond tools, it was found that EVC produced thinner and curlier chips and that better surface finish could be achieved, compared with conventional turning, owing to prohibition of formation of burrs and built-up edges. Therefore, we found EVC micro turning could be readily utilized to manufacture precision mold.

• 한국공작기계학회논문집
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• 제10권1호
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• pp.78-87
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• 2001

This paper deals with the study on the cutting characteristics in ball-end milling process. First of all, the effects of the geometric cutting conditions such as the cutting speed, feedrates and the path interval on the surface integrity were evaluat-ed by the analytical and the experimental approaches. Secondly, the cutting mechanism model was developed to predict the cutting force accurately. It is possible for the proposed model to predict the shape error, estimate system stability and build the reliable adaptive control system. A large amount of experimental set are performed to show the validities of the proposed theories and to investigate the effect of cutting geometry such as rubbing effects, burr effects and etc.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.725-729
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• 2000

This paper presented a new model of NC verification in ball end milling. The model verifies the over cut the under cut and the surface roughness using NC file generated from CAM and cutting condition. The model uses Z-map model to verify workpiece. In this paper, the model used the velocities of x, y and z direction and obtained a center point of a ball end mill for modeling Z-map of workpiece. To investigate the performance of the model simulation study was carried out. As the results, the model gave geometry accuracy of workpiece, the surface roughness and the chip loads in finish cutting that can predict tool chipping.

• 한국정밀공학회지
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• 제17권5호
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• pp.186-194
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• 2000

The purpose of this study is to investigate the difference in cutting characteristics of cermet, carbide and coated carbide tools in the similar application range via turning test of various conditions. The cermet and carbide tools in the range of ISO P10 grade were developed using optimum compositions with a view to obtaining a high toughness and hardness by PM process. First mechanical properties were characterized on these tools. Experimental results of wear behaviour and resistance to fracturing were presented and discussed in the turning of gray cast iron and alloy steels by cermet, carbide and coated carbide tools. The coated carbide tool shows similar cutting performance compared to the cermet, while the cermet has better combination of wear resistance and toughness of high speed (V=500m/min) cutting in comparison with carbide and coated carbide tools, and also shows a potentiality for cast iron cutting. Fe adhesive behaviour on the tools and surface roughness of workpieces were explained by chemical affinity between tools and workpieces.

• 콘크리트학회지
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• 제14권6호
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• pp.22-31
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• 2002

콘크리트 블록에는 속빈 콘크리트 블록, 치장 콘크리트 블록, 형틀 콘크리트 블록, 콘크리트 적층 블록 등이 있고, 콘크리트 적층 블록을 제외하면 모두 건축용으로 널리 쓰이는 재료이다. (1) 속빈 콘크리트 블록 속빈 콘크리트 블록이란 보강근을 삽입하는 속빈 부분을 갖고, 블록 벽체로 외력을 부담하는 것을 말한다. 속빈 콘크리트 블록은 건물의 경량화와 시공 기간의 단축이 가능하기 때문에 (그림 1)과 같이 벽체용으로 사용되거나 또는 칸막이용 등으로 많이 사용되는 대표적인 조적재이다 (2) 치장 콘크리트 블록 치장 콘크리트 블록은 철근으로 보강할 수 있는 공동이 있고, 미리 표면에 연마, 절삭, 씻어 내기, 쪼아 내기. 스플릿, 슬럼프, 리브붙임 등의 치장 마무리가 되어 있는 블록을 말한다. 도장 또는 착색만에 의한 치장 블록은 포함하지 않고 있다. 치장 블록은 주로 (그림 2)와 같이 담장에 많이 사용되고 있다. (3) 형틀 콘크리트 블록 형틀 콘크리트 블록은 형틀 콘크리트 블록조에 사용되는 것을 형틀 콘크리트 블록조란 형틀 블록을 조합하여 형틀로 하고, 그 중공부에 철근을 배치하고 콘크리트를 타설하여 내력벽을 형성하는 건축구조를 말한다. 형틀 블록을 조적한 후 외부에 나타나는 면에는 스플릿, 연마, 절삭, 씻어 내기, 쪼아 내기 등의 치장을 하기도 한다.(중략)

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.258-263
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• 2000

Under the optimal cutting conditions, determined the machinability difference of cutting tools are by two major factors. One is the geometric shape of the cutting tool, and the other is the tool materials or heat treatment or coating of the cutting tool. In this research, we evaluated the machinability of cutting tools with conventional HSS and P/M(powder metallurgy) which was made from the different of materials and manufacture processes. Tool wear, surface roughness, cutting force and squareness of machined workpiece were evaluated.

• 한국기계가공학회지
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• 제11권4호
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• pp.20-24
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• 2012

The objective of this study is to investigate proper cutting conditions of cellulose acetate(CA) for eyewear frames. Various cutting experiments with variation of spindle speeds and feed rates are conducted to evaluate the machinability of CA. The machinability of CA materials were discussed in terms of the cutting forces, surface roughnesses and chip formations. The cutting conditions of high spindle speeds and the feed per tooth of less than 0.05mm are recommended considering the surface roughnesses and chip formations. Also, the correlation between the surface roughness and the chip formation is investigated. These results are able to be applied to design the high-speed machine tool of CA frame.

• 한국기계가공학회지
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• 제11권4호
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• pp.31-38
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• 2012

In this paper, we selected primary cutting parameters that influence on surface roughness of cut bottom surface in end-milling for SM25C material. Those are overhang, depth of cut, feed rate and spindle speed. And then performed orthogonal array experiment and ANOVA by Taguchi method to determine that improved level combination of cutting parameters for betterment of working efficiency and surface roughness one of quality characteristics. And we verified a advisability of prediction model by verification test about level combination. From the results, main cutting parameter influences on surface roughness is spindle speed and the next is feed rate.

• 한국기계가공학회지
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• 제8권4호
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• pp.48-53
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• 2009

Inconel 718 alloy, widely used as material of aircraft engine, has a good mechanical property in high temperature, strong anti-oxidation characteristics in oxidated current over $900^{\circ}C$, and also is not easily digested in the air containing sulfur, therefore, its usage as mechanical component is expanding rapidly. Even though Inconel alloy 718 is difficult to machine, it requires highly precise processing/machining to sustain its component quality of high accuracy. In this paper, general turning operation conditions are tested to select the best cutting process condition by measuring surface roughness through implementing experiments with orthogonal array of cutting speed, feeding speed and cutting depth as processing parameters based on the Taguchi method. Optimal turning operation conditions are extracted from the proposed experimental models.

• 한국정밀공학회지
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• 제15권8호
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• pp.81-87
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• 1998

High-speed machining is one of the most effective technologies to improve productivity. Because of the high speed and high feedrate, high-speed machining can give great advantages for the machining of dies and molds. In this paper, high-speed machining for HP-4 die material was carried out with a coated tungsten carbide ball endmill. In the high-speed machining, the cutting force and surface roughness of workpiece show various characteristics in different cutting conditions. Especially, the surface roughness of the workpiece depends largely on pick feed and feed-per-revolution of the ball endmill. In the condition where pick feed and feed-per-revolution are equal, better surface roughness is measured. By obtaining good surface roughness at high speed, efficiency of machining can be increased.