• Proceedings of the KSME Conference
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• 2000.11b
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• pp.651-655
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• 2000

The objective of present work is to investigate experimentally the characteristics of heat transfer. A fluidized bed combustion has advantages of pollution control, fuel flexibility and excellent heat transfer. The present study investigates fundamental phenomena of bed-to-surface heat transfer in high temperature fluidized beds to improve design of immersed tube surface. The tested operating variables are bed temperature, supeficial velocity, mean size of bed material, and the rake angle of fin. Generally, heat transfer rates between the fluidized bed and immersed finned-tube are much higher than those of a smooth tube. A life time of finned-tube is generally longer than that of smooth tube.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.346-351
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• 2001

The technique of high speed machining is widely studied in machining field. Because the high efficiency and accuracy in machining can be obtained in high speed machining. Unfortunately the development of tool for high speed machining is not close behind that of machining tool. So in this study, we made 4 types flat end mill for obtaining data according to tool shape. Especially, we concentrated in helix angle and number of cutting edge. First we confirmed cutting condition by several experiments and measuring cutting force, tool life, tool wear and chip shape according to cutting length. In results, we acquired the fact that 45 degree helix angle and six cutting edge tool is suitable for high speed machining.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.104-116
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• 1998

This paper provides a review of the performance for SM45C using the CNC lathe. Under the constant cutting area, the tool wear for large feed rate is more than the small feed rate, and the progress goes more rapidly as the cutting speed is increased. This is caused by the friction between the workpiece and the bite. The average cutting force increases as the feedrate increases, and decreases as the cutting speed increases. This is because the effective rake/shear angle becomes smaller as the feedrate becomes larger. The higher is the cutting speed and the aspect ratio (the ratio for depth of cut to feedrate), the lower is the cutting force and the surface roughness. Also, for the optimal selection of the cutting conditions, many experimental graphical data were obtained. That is, the cutting force, the tool life, and the surface roughness were measured and investigated as the depth of cut and the feedrate changed. And the size effect was examined as the depth of the cut varied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1042-1047
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• 2001

A mechanistic model is developed to predict the thrust force and cutting torque of drilling process including wear. A mechanistic oblique cutting force model is used to develop the drilling force model. The cutting lips are divided into small elements and elemental forces are calculated by multiplying the specific cutting pressure with the elemental chip area. The specific cutting pressure is a function of chip thickness, cutting velocity, rake angle and wear. The total forces are then computed by summing the elemental forces. Measured cutting forces are in good agreement with the simulated cutting forces.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.810-813
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• 2000

Burr makes trobles on manufacturing process due to deburring cost, quality of products and productivity. This paper described the results of experimental study on the influence of the cutting parameters on the formation of exit burrs in face milling. The cutting parameters were investigated changing exit angle, rake nagle , lead angle in tool geometry as well as feed per tooth. Also we carried out experimets on several materials. Using the result of experimental study, burr types are classified according to appearance and formation mechanism in exit burr and we are considered the burr formation in each type of burr.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.604-607
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• 2003

This study investigates the micro-cutting of cemented carbides using PCD(polycrystalline diamond) and PCBN(polycrystalline cubic boron nitride) cutting tools are performed with SEM direct observation method. The purpose of this study is to make clear the cutting mechanism of cemented carbides and the fracture of WC particles at the plastic deformation zone in orthogonal micro-cutting. And also to achieve systematic understanding, the effect of machining parameter on chip formation and machined surface was investigated, including cutting speed. depth of cut and various tool rake angle.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.141-147
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• 1998

A plastically deformed layer in the precision machined surface affects in various forms the physical properties of machined components such as the fatigue strength, the dimensional instability, microcracks and the stress corrosion cracking. These physical properties, so called surface integrity, are very important for designing highly stressed and critically loaded components. Typical plastic strains in the precision machined surface are very difficult to measure, since they are located within a very short distance from the surface and they change very rapidly. A new way is suggested to determine the residual strain in plastically deformed materials by analyzing the plastically deformed layer after a subsequent recrystallization process. This investigation is to explore a new technique for measuring plastic strain in machining applications, and in particular, to and the effect of cutting parameters(rake angle, depth of cut, specific cutting energy), on the plastic strains and strain energy.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.3
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• pp.53-60
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• 1992

This paper deals with developing an Expert system for tool selection using knowledge base system approach, and its application. For the sake of building of knowledge base, the information from process through sensor, tool handbook and interview with expert are referrenced and managed. The system developed shows good application flexibility in providing the actual cutting process with the selection of tool(insert, holder) and cutting conditions(feed, speed, rake type, and so on), is found as a useful system for real-time machining process. The Expert system for tool selection is written in TURBO PROLOG ver. 2.0 for inference engine capability, and can be run in interactive mode for user friendliness. In order to apply the system developed in actual cutting process, more parameters should be considered and scrutinized, and the system should be further extended in modular basis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.577-580
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• 2003

Stress state of chip formation zone is one of the main problems in metal cutting mechanics. In two-dimensional case this process is usually considered as consistent shears of work material along single of several shear surfaces. separating chip from workpiece. These shear planes are assumed to be trajectories of maximum shear stress forming corresponding slip-line field. This paper suggests new approach to the constriction of slip-line field, which Implies uniform compression in chip formation zone. On the base of given model it has been found that imaginary shear line in orthogonal cutting is close to the trajectory of maximum normal stress and the problem about its determination have been considered. It has been shown that there is a second central slip-line field inside chip, which corresponds well to experimental data about stress distribution on tool rake face and tool-chip contact length. The suggested model could be useful in solution of various problems of machining.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.50-55
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• 2008

In this paper, we propose a new shape compensation scheme to make up for the difference in groove radius between the formed tools and the machined bearing raceways, which inherently takes place during machining the ball bearing raceways by the turning process using conventional formed tools. The associated conventional methods of the formed tool design and its modification such as a simple depth compensation method and a graphical compensation method are introduced and the latter, which has been known to be the better of the two, is experimentally investigated in detail to reveal its drawback. The algorithm is given and it is applied to develop a formed tool design program. The program developed by the presented approach is successfully applied to design the formed turning tool for the bearing raceways.