• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.2
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• pp.143-148
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• 2016

A micro end mill is one of the precise tools used in machining ultra-precision products such as microchannel and micropatterned mold. To achieve the required precision of these products, several studies investigated the cutting force, burr formation, and burr generation mechanism of micro end mills; however, there are few studies on the alignment of micro tools, which is the foundation of machining. Hence, in this investigation, relation expressions were derived to determine the relation between the misalignment parameters and the machining accuracy. At the same time, the effect of the machining parameters was analyzed using a multiple linear regression analysis and the analysis of variance. The results indicate that the tilting angle of a micro tool has more influence on the machining accuracy than other parameters.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.59-64
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• 2002

Recently the applications of high speed machining are increasing due to the need for high performance and high accuracy machining and machining for difficult-to-cut material. However, the high speed machining also accompanies some problems: the product quality can be degraded due to the tool wear and the product cast can go up due to frequent tool replacements. Therefore, it is necessary to develop a technique of quantitative tool wear measurement to determine the precise timing for tool replacement. In this respect, this study suggests a reliable technique far the reduction of error components by developing a system using a CCD camera and an exclusive jig to be able to precisely measure the size of tool wear in flat end mill for high speed machining.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.2
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• pp.116-116
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• 1999

In this study we propose a novel approach with which design engineers can define and design free-from surface more easily. Free-from surface is defined as a parameterics shape which consists of a set of contr ol points. Parametric shape which not only has the advantage of allowing users to perform design changes efficiently, but also provides designers with a natural design environment in which they can do their work more naturally and creatively. The objective of this study is to develop a PC level freeform surface modelling system which explicitly represents information of part geometry. In this study, freeform surface modeling system consist of three modules : freeform surface modeler, input/output modules and interface with Database. In recent year there are increasing demands for the 5-axis machining of a complicated shape. This study is the development of a CAM software system (or NC module) for the 5-axis machining of a general shape with a flat-end mill, a round-end mill, a ball-end mill.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.6
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• pp.1-7
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• 2003

The experimental research was conducted to find an end mill with an ideal helix angle, which has a superior anti-vibration effect and a low machining tolerance. A conventional endmill which all low blades are $30^{\circ}$ helix angles and a different helix angle endmill which the opposite two blades are $30^{\circ}$ and the other opposites are different helix angles were studied. The cutting farce, machining tolerance and surface roughness were obtained. The AE signals appeared to have low values in up-milling rather than in down-milling. These are also appeared to have low values at low spindle revolutions rates. The cutting force values of Fxy and Fxyz were found to be increased according to the value of helix angle. In up-milling, it was difficult to find a definite tendency in machining tolerance, but in down-milling machining tolerance of the different helix angle end mill was found to be lower than that of the convention end mill. There is a definite tendency that the surface roughness gets better as the RPM increases. In down-milling, Type A($25^{\circ}$＋$30^{\circ}$) appeared to bring the most satisfactory result.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.196-201
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• 2003

The experimental research was conducted to find an end mill with an ideal helix angle, which has a superior anti-vibration effect and a low machining-tolerance. A conventional endmill which all four blades are $30^\circ$ helix angles and a different helix angle endmill which the opposite two blades are $30^\circ$ and the other opposites are different helix angles were studied. The cutting force, machining tolerance and surface roughness were obtained. The AE signals appeared to have low values in up-milling rather than in down-milling. These are also appeared to have low values at low spindle revolutions rates. The cutting force values of Fxy and Fxyz were found to be increased according to the value of helix angle. In up-milling, it was difficult to find a definite tendency in machining tolerance, but in down-milling, machining tolerance of the different helix angle end mill was found to be lower than that of the convention end mill. There is a definite tendency that the surface roughness gets better as the RPM increases. In down-milling, Type $A(25^\circ+30^\circ)$ appeared to bring the most satisfactory result.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.4
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• pp.440-451
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• 1985

This study is concerned with the analysis of cutting force system acting on ball-nose end mill in three-dimensional surface machining process. Conical tipped circular cutting edge element model and free surface machining process types are proposed to apply oblique cutting theory, and then derived equations are used for numerical approach of cutting force curves by matrix method. This approach has a good agreement with experimental results both in magnitude and shape within the range of 15 percent, which was conformed on 6061-T6 aluminum workpiece having twofold curvatured surface. From the cutting load variation to edge location, it is confirmed that circular cutting edge shapes has a better cutting ability than that of straight and both have a singularity near a tool point. It is also verified that what kind of machining condition is recommendable for three-dimensional machining process in connection with deflection of the cutter to workpiece and tool point wearing or system stability.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.3
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• pp.63-70
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• 2020

Two rotational motions of the 5-axis machine tool maximize the degree of freedom of the tool axis vector, which improves tool accessibility; however, this lowers feed speed and rigidity, which impairs machining stability. In addition, cutting efficiency is lowered when compared with a flat end mill because typically, the ball-end mill is used when machining by rotational motion. This study increased cutting efficiency by using a corner radius flat end mill during impeller roughing. Furthermore, we proposed a fixed controlled machining of the rotary motion using geometric shape information to improve the feed speed and machining stability. Finally, we proposed a finishing tool path generation method using a vector net to increase the convenience and practicality of tool path generation. To verify its effectiveness, we compared the machining time, shape accuracy, and surface quality of the proposed method and an existing dedicated module.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.1-8
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• 2007

The ultra-fine tungsten carbide(WC) powders have been actively used in the cemented carbides industry, because they have excellent mechanical properties such as high hardness, strength, and toughness. In this study, ultra-fine WC-Co alloys powders have been fabricated by thermochemical and thermomechanical process such as spray conversion process or high energy ball milling. The non-coated end-mill which is made of ultra-fine tungsten carbide is investigated by measuring cutting force, tool wear, tool life, and surface roughness profile according to cutting length. The machining test was conducted with high hardened workpiece and their performances are investigated in high speed cutting conditions. Also, the relationship between the machining characteristics and the Co contents are investigated under various high speed cutting conditions.

• Transactions of Materials Processing
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• v.28 no.4
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• pp.183-189
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• 2019

Cylindrical worm reducers are generally used in various fields and forms throughout the industry, and demand is increasing due to their role as an integral part of the industry. Market trends require high-load, high-precision components, and small-sized reducers with large loads. When using a cylindrical worm reducer, a reducer designed with a reduced center distance while maintaining the same output torque results in gear wear. To overcome this difficulty, an enveloping worm gear reducer is introduced and studied. In this paper, three types of end mill tools are used to evaluate the tooth profile accuracy for each tool shape during machining of the tooth profile for a non-developed surface worm thread. The effect of the endmill shape on the accuracy of the tooth profile was analyzed by performing 3D modeling of the surrounding worm tooth profile based on the Hindley method. In this study, we analyzed tooth profile accuracy, tooth surface roughness, and tooth surface machining time, etc. Through the study, efficient machining conditions for the enveloping worm gears and the influence of parameters on the process were presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.11
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• pp.47-56
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• 2013

Rolling speed, roll gap, and cooling pattern in hot strip finishing mill process should be determined before inserting strip into roll. Such parameters are initially calculated by a mathematical set-up model. The technique to find adequate roll speed via a mathematical model has inherently limit because required working conditions are various and rolling process is nonlinear. To improve the accuracy of initial rolling speed for a finishing mill, this paper suggests a correction technology for initial rolling speed. The proposed method was implemented in hot strip mill process. As the results, the magnitude of width error in strip head-end part caused by excessive strip tension was decreased remarkably.