• Title, Summary, Keyword: 하향절삭

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Effects of Cutting Speed and Feed Rate on Axial Shape in Side Walls Generated by Flat End-milling Process (평엔드밀링 공정에서 절삭속도 및 이송속도가 측벽의 축방향 형상에 미치는 영향)

  • Kim, Kang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.5
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    • pp.391-399
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    • 2017
  • This paper presents the effects of the cutting speed and feed rate on the axial shape of flat end-milled down cut side walls. Experiments were performed using the cutting speed, tool diameter, and feed per tooth as variables, and the thrust force and axial shape were measured as the experimental results. The results of this study confirmed that a smaller feed per tooth, which is proportional to the value obtained by dividing the feed rate by the cutting speed, results in a higher axial shape accuracy. In addition, the axial shape can be simplified to a form in which two straight lines having different slopes meet at a singular point. Therefore, it was concluded that the shape accuracy could easily be estimated during the operation and improved by adjusting the feed per tooth.

A Study on the Improvement of Surface Waviness by Cutting Force Control (밀링머신의 절삭력 제어를 통한 표면굴곡도 향상에 관한 연구)

  • 오준호;정충영
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.2
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    • pp.206-214
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    • 1988
  • To improve the surface waviness in the peripheral milling, the feedrate is controlled so that the cutting force measured in the normal direction to the workpiece is constant. A discrete time first order model between the feedrate and the tool deflection is derived for the control. It has been shown by the analysis that the tool deflection is directly related to the feedrate and largely affects the surface waviness during cutting. The experimental results shown that the surface waviness is drastically improved by the proposed methods.

A study on the Analysis and Evaluation of Cutting forces for High Speed Machining by a Ball-end mill (볼엔드밀의 고속가공에서 절삭력 분석 및 평가에 관한 연구)

  • Lee Choon Man;Ryu Seung Pyo;Ko Tae Jo;Jung Jong Yun;Chung Won Jee
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.5
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    • pp.167-174
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    • 2005
  • High-speed machining is one of the most effective technologies to improve productivity Because of the high speed and high feed rate, high-speed machining can give great advantages for the machining of dies and molds. This paper describes on the analysis and evaluation of cutting force in high-speed machining. Cutter rotation directions, slope directions, spindle revolution and depth of cut are control factors for cutting force. The effect of the control factors on cutting force is investigated for the high speed machining of STD11.

Improvement of the Accuracy in Machining Deep Pocket by Up Milling (상향절삭에 의한 깊은 홈 가공시 정밀도 향상에 대한 연구)

  • Lee, Sang-Kyu;Ko, Sung-Lim
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.4
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    • pp.220-228
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    • 1999
  • The machining accuracy has been improved with the development of NC machine tools and cutting tools. However, it is difficult to obtain a high degree of accuracy when machining deep pocket with long end mill, since machining accuracy is mainly dependant on the stiffness of the cutting tool. To improve surface accuracy in machining deep pocket using end mill, the performance by down cut and up cut is compared theoretically and experimentally. To verify usefulness of up milling, various experiments were carried out. As a result, it is found that up milling produce more accurate surface than down milling in machining deep pocket. For effective application of up milling, various values in helix angle, number of teeth, radial depth of cut and axial depth of cut are applied in experiment.

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Prediction of Cutting Force in Down End Milling (엔드밀의 하향절삭시 절삭력 예측)

  • 이영문;이선호;태원익
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.907-911
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    • 2000
  • In this study, a modified model for prediction of cutting force components in down end milling process is presented. Using this cutting force components of 4-tooth endmills with various helix angles have been predicted. Predicted values of cutting force components are well coincide with the measured ones. As helix angle increases overlapping effects of the active cutting edges increase and as a result the amplitudes of cutting force components decrease.

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A Study on the Cutting Force and Machining Error on the Inclined Plane in Ball-end Milling (볼엔드밀에 의한 경사면 가공시 절삭력 및 가공 오차에 관한 연구)

  • Doo, Seung;Hong, Joo-Won;Suh, Nam-Sub
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.7
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    • pp.112-119
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    • 2001
  • In modern manufacturing, many products that have geometrically complicated features, including three-dimensional sculptured surfaces, are being designed and produced to meet various sophisticated functional specifications. The cutting force is required not only for the design of machine and cutting tools, but also for the determination of the cutting conditions for the various machining operations. The ball-end mill is deflected by the cutting force and, the tool deflection is one of the main reasons of the machining errors on a free-form surface. Hence, The cutting force generated in the ball-end milling is the most important property of the machining. The purpose of this study is to find the characteristics of the cutting force in inclined plane and the resultant machining errors in the ball-end milling process. Although the depth of cut is constant in the inclined plane, the cutting force area varies due to the hemisphere of the ball-end mill.

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Effects of Cutting Area on Straightness Characteristics in Side Walls Caused by Form Generation Mechanism in End-Milling Process (엔드밀링 공정의 형상창성기구에 의하여 절삭면적이 측벽 진직도 특성에 미치는 영향)

  • Kim, Kang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.10
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    • pp.1269-1278
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    • 2013
  • The cutting area changes periodically in the end-milling process because of its form generation mechanism. In this study, the effects of the cutting area on end-milled side walls are studied by developing a cutting area model that simulates the area formed by engagement between a workpiece and a cutting edge of the end mill. To do this, the straightness profile of the side wall in the axial direction is investigated. Models for estimating the cutting area and the transition point, where the slope of the straightness profile changes suddenly, are verified from real end-milling experiments under various radial and axial depth of cut conditions. Through this study, it is confirmed that the final end-milled side wall is generated in the regions where cutting areas are constant and decreasing in the down-cut. Similarly, in stable up-cut, it is also generated in the regions where cutting areas are increasing and constant. It is found that the transition point appears when the region changes.

Cutting Characteristics in Down-End Milling with Different Helix Angles (하향엔드밀링시 헬릭스각에 따른 절삭특성변화)

  • 이영문;장승일;서민교
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.77-82
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    • 2003
  • In end milling process, undeformed chip thickness and cutting force vary periodically with phase change of the tool. Recently, a model has been proposed to simulate the shear and friction characteristics of an up-end milling process in terms of the equivalent oblique cutting to this. In the current study, the varying undeformed chip thickness and the cutting forces in a down-end milling process have been replaced with the equivalent ones of oblique cutting. And, the down-end milling characteristics of SM45C has been compared with that of the up-end milling previously presented with different helix angles.

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Relationship Between Flat End-mill Shape and Geometrical Characteristics in Side Walls Generated by End-milling Process (엔드밀링 공정에 의하여 생성된 측벽의 기하학적 특성과 평엔드밀 형상 사이의 관계)

  • Kim, Kang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.1
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    • pp.95-103
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    • 2015
  • This paper presents the effects of the tool shape on the geometrical characteristics of flat end-milled side walls. A tool shape is characterized by such parameters as helix angle, number of cutting edges, and diameter. The geometrical characteristics of the side walls are represented by the surface profiles in the feed and axial directions, which are orthogonal to each other. The geometrical defects in each direction are estimated based on the instantaneous apparent cutting areas, which are represented by the interference area between the tool and workpiece and that between the cutting edge and workpiece. It is confirmed that a geometrical defect in the feed direction is formed when the tool leaves the workpiece and the curvature of the tool path changes. Defects in the axial direction are also found in the side walls, except for the defect zone in the feed direction. An up-cut using an end-mill with a steeper helix angle, a greater number of cutting edges, and a smaller diameter are thus found to improve the geometrical accuracy of end-milled side walls.

Shear and Friction Characteristics in Down-End Milling with Different Helix Angles (하향엔드밀링시 헬릭스각에 따른 전단 및 마찰특성변화)

  • 이영문;장승일;서민교;손정우
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.2
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    • pp.17-24
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    • 2004
  • In end milling process, undeformed chip thickness and cutting forces vary periodically with phase change of the tool. Recently, a model has been proposed to simulate the shear and friction characteristics of an up-end milling process in terms of the equivalent oblique cutting to this. In the current study, a down-end milling process has been replaced with the equivalent oblique cutting process. And shear and tool-chip friction characteristics variation of SM45C steel has been studied using the end-mills of different helix angles. The specific shear and friction energy consumed with helix angle of $50^{\circ}$ is somewhat larger than those of$30^{\circ}$ and $40^{\circ}$. The specific shear energy consumed is about 76-77% of the specific cutting energy regardless the helix angles.