• Title/Summary/Keyword: tool position

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Error Synthesis Modeling and Compensation Algorithm of a 5-Axis CNC Machine Tool (5축 CNC 공작기계의 오차합성모델링 및 보정 알고리즘)

  • Yang, Seung-Han;Lee, Chul-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.8
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    • pp.122-129
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    • 1999
  • A 5-axis CNC machine tool is more useful compared with a 3-axis machine tool, because the position and the orientation of a tool tip can be controlled simultaneously. Unlike the 3-axis machine tool, the 5-axis machine tool has the volumetric position error and volumetric orientation error due to the quasi-static error of each machine tool joint which is a major source of machined part error. So, the generalized error synthesis model of the 5-axis CNC machine tool was developed to predict and to compensate for the volumetric position error and the volumetric orientation error. It was proposed that a compensation algorithm to correct simultaneously the volumetric position error and the volumetric orientation error of the 5-axis CNC machine by error inverse kinematic.

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Tool Deflection and Geometric Accuracy to the Change of Inclination Position Angle during Machining Sculptured Surface (곡면가공시 경사위치각 변화에 따른 공구변형과 형상정밀도)

  • 왕덕현;박희철
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.4
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    • pp.55-64
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    • 2001
  • In this study, hemisphere and cylindrical shapes were machined for different tool paths and machining conditions with ball endmill cutters. Tool deflection, cutting forces and shape accuracy were measured according to the inclination position of the sculptured surface. As the decreasing of inclination position angle, the tool deflection was increased due to the decreased cutting speed when the cutting edge is approaching toward the center. Tool deflection when upward cutting is obtained less than that of downward cutting and down-milling in upward cutting showed the least tool deflection for the sculptured surface. Roundness values were found in least roundness error when down-milling in upward cutting. It is obtained the very little difference between 90。and 45。 of inclination position angle. The best surface roughness value was obtained in upward up-milling and showed different tendency with tool deflection and cutting force. For down-milling, the cutting resistance of the side wall direction is larger than that of feed direction. Therefore, this phenomenon which is received over cutting resistance can be caused of chatter.

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Statistical Analysis of the Position Errors of a Machine Tool Using Ball Bar Test (볼바 측정을 통한 공작기계 위치오차의 통계적 분석)

  • 류순도;양승한
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.501-504
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    • 2001
  • The use of error compensation techniques has been recognized as an effective way in the improvement of the accuracy of a machine tool. The laser measurement method for identifying position errors of machine tool has the disadvantages such as high cost, long calibration time and usage of volumetric error synthesis model. Accordingly, this paper deals with analysis of the position errors of a machine tool using ball bar test without using complicated error synthesis model. Statistical analysis method was adopted in this paper for deriving position errors using hemispherical helix ball bar test.

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Position Control of Ultra-Precision Machine Tool Postusing Piezoelectric Material) (압전재료를 이용한 초정밀 가공기용 공구위치제어)

  • 김태형
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1996.10a
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    • pp.28-33
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    • 1996
  • This paper presents a position control of ultra-precision machine tool post using piezoelectric material. A stack-type piezoelectric actuator is employed in a hinge-type tool holder. An assumed linear transfer function of the practical nonlinear plant is established through the comparison of transfer functions and step responses in the experiments and the simulations. Several types of feedforward/feedback controllers are designed via computer simulations using the assumed linear transfer function, The position tracking control experiments are undertaken to show the control efficiency of each controller.

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Machining Characteristics of Hemisphere Shape by Ball Endmilling (볼엔드밀가공에 의한 구면형상의 가공특성)

  • Wang, Duck Hyun;Kim, Won Il;Lee, Yun Kyeong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.1 no.1
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    • pp.5-14
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    • 2002
  • Hemisphere shapes were machined for different tool paths and machining conditions with ball endmill cutters. It was also found out how feedrate affect the precision of the machining and also tried to study the most suitable feedrate in specific cutting condition. Tool deflection, cutting forces and shape accuracy were measured according to the inclination position of the sculptured surface. As the decreasing of inclination position angle, the tool deflection was increased due to the decreased cutting speed when the cutting edge is approaching toward the center. Tool deflection when upward cutting IS obtained less than that of downward cutting and down-milling in upward cutting showed the least tool deflection for the sculptured surface. For down-milling, the cutting resistance of the side wall direction is larger than that of feed direction. It was found that the tool deflection is getting better as tool path is going to far from the center for convex surface.

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Development of a Vision-based Position Estimation System for the Inspection and Maintenance Manipulator of Steam Generator Tubes a in Nuclear Power Plant

  • Jeong, Kyung-Min;Cho, Jae-Wan;Kim, Seung-Ho;Kim, Seung-Ho;Jung, Seung-Ho;Shin, Ho-Chul;Choi, Chang-Whan;Seo, Yong-Chil
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.772-777
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    • 2003
  • A vision-based tool position estimation system for the inspection and maintenance manipulator working inside the steam generator bowl of nuclear power plants can help human operators ensure that the inspection probe or plug are inserted to the targeted tube. Some previous research proposed a simplified tube position verification system that counts the tubes passed through during the motion and displays only the position of the tool. In this paper, by using a general camera calibration approach, tool orientation is also estimated. In order to reduce the computation time and avoid the parameter bias problem in an ellipse fitting, a small number of edge points are collected around the large section of the ellipse boundary. Experiment results show that the camera calibration parameters, detected ellipses, and estimated tool position are appropriate.

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Control Method for the Tool Path in Aspherical Surface Grinding and Polishing

  • Kim, Hyung-Tae;Yang, Hae-Jeong;Kim, Sung-Chul
    • International Journal of Precision Engineering and Manufacturing
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    • v.7 no.4
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    • pp.51-56
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    • 2006
  • This paper proposes a control algorithm, which is verified experimentally, for aspherical surface grinding and polishing. The algorithm provides simultaneous control of the position and interpolation of an aspheric curve. The nonlinear formula for the tool position was derived from the aspheric equation and the shape of the tool. The function was partitioned at specific intervals and the control parameters were calculated at each control section. The position, acceleration, and velocity at each interval were updated during the process. A position error feedback was introduced using a rotary encoder. The feedback algorithm corrected the position error by increasing or decreasing the feed speed. In the experimental verification, a two-axis machine was controlled to track an aspherical surface using the proposed algorithm. The effects of the control and process parameters were monitored. The results demonstrated that the maximum tracking error with tuned parameters was at the submicron level for concave and convex surfaces.

Five-axis CL Data Generation by Considering Tool Swept Surface Model in Face Milling of Sculptured Surface (공구이동궤적 모델을 이용한 5축 페이스밀링 가공데이터 생성)

  • 이정근;박정환
    • Korean Journal of Computational Design and Engineering
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    • v.9 no.1
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    • pp.35-43
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    • 2004
  • It is well known that the five-axis machining has advantages of tool accessibility and machined surface quality when compared with conventional three-axis machining. Traditional researches on the five-axis tool-path generation have addressed interferences such as cutter gouging, collision, machine kinematics and optimization of a CL(cutter location) or a cutter position. In the paper it is presented that optimal CL data for a face-milling cutter moving on a tool-path are obtained by incorporating TSS(tool swept surface) model. The TSS model from current CL position to the next CL position is constructed based on machine kinematics as well as cutter geometry, with which the deviation from the design surface can be computed. Then the next CC(cutter-contact) point should be adjusted such that the deviation conforms to given machining tolerance value. The proposed algorithm was implemented and applied to a marine propeller machining, which proved effective from a quantitative point of view. In addition, the algorithm using the TSS can also be applied to avoid cutter convex interferences in general three-axis NC machining.

Position Control of Ultra-Precision Machine Tool Post using Piezoelectric Material(1) (압전 재료를 이용한 초정밀 가공기용 공구 위치 제어(1))

  • 김승한;송하성;송재욱;김의중
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.162-166
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    • 1996
  • This paper presents a position control of ultra-precision machine tool post using piezoelectric material. A stack-type piezoelectric actuator Is employed in a hinge-type tool holder. An assumed linear transfer function of the practical nonlinear plant is established through the comparison of transfer functions and step responses in the experiments and the simulations. Several types of feedforward/feedback controllers are designed via computer simulations using the assumed linear transfer function. The position tracking control experiments are undertaken to show the control efficiency of each controller.

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Evaluation of Effectiveness of Anatomical Rotation Change Image by Aid Tool in Shoulder MRArthrography (Shoulder MRArthography 검사 시 보조기구를 이용한 해부학적 회전 변화 영상에 대한 유용성 평가)

  • Kim, Hyeong-Gyun;Jung, Jae-Eun;Jung, Hong-Moon
    • Journal of the Korean Society of Radiology
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    • v.6 no.4
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    • pp.299-303
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    • 2012
  • Shoulder MRArthrography was performed to get an accurate diagnosis about complex anatomical structure in shoulder joint. We carried out how the changes of anatomical rotations in shoulder joint could bring certain diagnosis effects on MRI images for various shoulder humerus positions; Neutral position, Internal rotation position and External rotation position. In addition, we prepared an aid tool in oder to maintain the right posture of a patient. This aid tool was made by adapting Modeling Design Program. By virtue of this aid, we obtained the following result. Shoulder MR Arthrography by the External rotation position for anatomical structure diagnosis was the most suitable in diagnostic evaluations of important anatomical structures in shoulder joint such as Biceps tendon, Supera-spiatus tendon, Sub-scapularis tendon, Labrum and Sub-acromial space.