• Title/Summary/Keyword: Machined error

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A Study on the Virtual Machining CAM System : Prediction and Experimental Verification of Machined Surface (실 가공형 CAM 시스템 연구: 가공형상의 예측 및 실험 검증)

  • 김형우;서석환;신창호
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.961-964
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    • 1995
  • For geometric accuracy in the net shape machining, the problem of tool deflection should be resolved in some fashion. In particular, this is crucial in finish cut operation where slim tools are used. The purpose of this paper is to verify the validity and effectiveness of the prediction model of the machined surface. Experimental results are presented for the cut of steel material with HSS endmill of diameter 6mm on machining center. The results shows that 1) the machining error due totool deflection is serious even in the low cutting load, 2) by using the mechanistic simulation model with experimental coefficients, the machining error was predicted with maximum prediction error of 10% which was significantly reduced to the desired level by the path modification method.

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A Study on the Effect of Tip Radius of Diamond Stylus Machined by Ion Sputter in Surface Roughness Measurement (이온스파터 가공한 다이아몬드 촉침의 선단반경이 표면거칠기 측정에 미치는 영향)

  • Han, Eung-Gyo;No, Byeong-Ok;Yu, Yeong-Deok
    • Journal of the Korean Society for Precision Engineering
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    • v.7 no.3
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    • pp.37-47
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    • 1990
  • In accordance with the high precision of mechanical elements, it has been required to high precision in surface roughness measurement and, therefore, stylus tip radius is manufa- ctured less than 2 .mu. m through ion sputter machining. In this experiment, by suing ion sputter machined stylus pf fine tip, radius and lapping machined stylus, surface roughness of standard specimens, silicon wafer were measured and then Rmax, Ra, RMS value were investi- gatedaccording to the variation of tip radius of stylus. As a result, measuring error due to the variation of stylus tip radius in surface roughness measurement was decreased by using ion sputter machined stylus and also the measuring accuracy was improved. And the measuring variation of Ra, RMS calculated from correlation coefficient lager than 0.9 on the wave of short period and amplitude using ion sputter machined stylus of fine tip radius.

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A Study on Detection of Runout Eccentric Error Using CCS Sensor at CNC Lathe (CNC선반에서 주축변위센서를 이용한 가공편심오차의 검출에 관한 연구)

  • 양재생;맹희영
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2002.10a
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    • pp.468-473
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    • 2002
  • This paper presents the methodology for measuring eccentricity of the cylindricaliy machined part using CCS(Cylindrical Capacity Spindle Sensor) signal in the CNC turning process. In order to investigate the relationships between CCS orbits and eccentricities, the initial conditions for various eccentricity state and machining process is applied to the experimental strategy. AS a result, it is considered the linearities of CCS signal and magnitude of eccentricity of machined cylindrical surfaces based on the possibility as a automatic detection apparatus for the CNC lathe.

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Prediction of Cutting Force and Machinig Error in the Ball-end Milling Process (공구변형을 고려한 볼엔드밀의 절삭력과 가공오차 예측)

  • 조필주;김규만;주종남
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.1003-1008
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    • 1997
  • In this paper, the prediction of cutting force and tool deflection in the ball-end milling process are studied. Identifying various cutting region using Z-map, cutting force in the ball-end milling process can be predicted. Cutting force deflects the tool and the tool deflection changes the cutting force. Tool deflection is included in the cutting force prediction. Tool deflecition also causes machining error of the machined surface. A series of experiments were performed to verify the simulated cutting force and machining error.

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Geometric Accuracy Measurement of Machined Surface Using the OMM (On the Machine Measurement) System

  • Kim, Sun-Ho;Lee, Seung-Woo;Kim, Dong-Hoon;Lee, An-Sung;Lim, Sun-Jong;Park, Kyoung-Taik
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.4
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    • pp.57-63
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    • 2003
  • Machining information such as form accuracy and surface roughness is an important factor for manufacturing precise parts. To this regard, OMM (On the Machine Measurement) has been researched for last several decades to alternate CMM (Coordinate Measurement Machine) process. In this research, the OMM system with a laser displacement sensor was developed for measuring form accuracy and surface roughness of the machined workpiece on the machine tool. The surface roughness was estimated comparing the sensory signal with the reference data measured from master specimen. Also, form accuracy was determined from the moving averaged raw data. In addition, the geometric error map constructed beforehand using the geometric errors of the machine tool was used to compensate the obtained form accuracy. The overall performance was compared with CMM result, and verified the feasibility of the measurement system.

Development of a Surface Roughness Measurement Method Using Reflected Laser Beam Image and Its Application (레이저광 반사 화상을 이용한 표면 거칠기 측정법의 개발과 적용)

  • Yun, Yun-Feng-Shen;Kim, haa-young;An, jung-hwan;Chi, ei-jon
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.11
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    • pp.51-57
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    • 2001
  • A light beam reflected from a machined surface generally containes information concerning about its surface roughness. This study examines and proposes a surface roughness measurement technique for on-machine measurement of machined surfaces. The technique is based on the measurement of a reflected laser beam pattern and the statistical analysis of its light intensity distribution. The surface roughness was found to be closely related to the standard deviation of the light intensity on the primary axis of the reflected pattern. An image acquisition device is made up of a laser diode, a half mirror, a screen, and a CCD camera. The exact image with the primary and secondary axes of a reflected laser beam pattern is calculated through such image processing algorithm as thresholding, edge detection, image rotation, segmentation, etc. A median filter and a surrounding light correction algorithm are improve the image quality and reduce the measuring error. Using the developed measuring device the effect of screen materials and workpiece and workpiece materials was investigated. Experimental results regarding to relatively high-quality surfaces machined by grinding, polishing, lapping processes have shown the measurement error is within 10% in the range of $0.1{mu}m~0.8{\mu}m R_q.$Therefore, the proposed method is thought to be effectively used when quick measurements is needed with workpieces fixed on the machine.

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Machined Surface Inspection Based on Surface Fairing on the Machine Tool (곡면평활화를 고려한 공작기계상에서의 가공곡면 검사)

  • Lee, Se-Bok;Kim, Gyeong-Don;Jeong, Seong-Jong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.4 s.175
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    • pp.937-945
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    • 2000
  • The assessment of machined surface is difficult because the freeform surface must be evaluated by surface fairness as well as dimensional accuracy. In this study, the machined freeform surface is modeled by interpolating the data measured on the machine tool into the mathematical continuous surface, and then the surface model is improved with the parameterization to minimize surface fairness. The accuracy reliability of the measured data is confirmed through compensation of volumetric errors of the machine tool and of probing errors. Non-uniform B-spline surface interpolation method is adopted to guarantee the continuity of surface model. Surface fairness is evaluated with the consideration of normal curvature on the interpolated surface. The validity and usefulness of the proposed method is examined through computer simulation and experiment on the machine tool.

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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