• Title/Summary/Keyword: Roundness error

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A Study on the Modeling and Prediction of Machined Profile in Round Shape Machining (동근형상가공의 형상모델링과 예측에 관한 연구)

  • 윤문철
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.04a
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    • pp.659-664
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    • 2000
  • In this paper, We have discussed on the modeling of machined outer geometry which was established for the case of round shape machining, also the effects of externally machined profile are analyzed and its modeling realiability was verified by the experiments of roundness testing, especially in lathe operation. In this study, we established harmonic geometric model with the parameter harmonic function. In general, we can calculate the theoretical roundness profile with arbitrary multilobe parameter. But in real experiments, only 2-5 lobe profile was frequently measured. the most frequently ones are 3 and 5 lobe profile in experiments. With this results, we can predict that these results may be applies to round shape machining such as turning, drilling, boring, ball screw and cylindrical grinding operation in bearing and shaft making operation with the same method. In this study, simulation and experimental work were performed to show the profile behaviors. we can apply these new modeling method in real process for the prediction of part profile behaviors machined such as in round shape machining operation.

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A study on the characteristics of the convex surface machining in CNC milling (CNC 밀링에 의한 볼록곡면 가공시의 가공특성에 관한 연구)

  • Han, Heung-Sam;Lee, Dong-Ju
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.11
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    • pp.45-51
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    • 1995
  • In order to suggest the proper cutting conditons of the CNC milling machining for the free-form surface, some experments were carried out. In the experiments, the influence of cutting conditions on a inclined spherical surface were examined by geometrical analysis. In this study, the roundness and cutting force were measured to know the effect of several cutting conditions on the machined surface and the cutting characteristics were carefully investigated. The results obtained in this study are aw follows. 1) If the tool ha s enough rigidity, we can get better dimensional accuracy in up-ward cutting than down- ward cutting. 2) A great roundness error is appeared on the surface declined under 30 degress to the horizontal plane in circular machining by a bal end mill. 3) If the thrust force is increased, the stability of tool is decreased. And the phenomenon is apperared in great in down-ward cutting than up-ward cutting.

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Development of Online Realtime Positioning Error Compensation System for CNC Machine Tools (CNC 공작기계용 온라인 실시간 위치오차 보정시스템의 개발)

  • Chung, Chae-Il;Kim, Jong-Won;Nam, Weon-Woo;Lee, Sang-Jo
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.10
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    • pp.45-52
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    • 1999
  • The online realtime positioning error compensation system 'SKY-PACS' is developed to correct geometric errors, thermal errors and tool deflection errors induced by cutting forces on the vertical machining center. 'SKY-PACS' communicates position commands and position compensation signals with the CNC controller at 100Hz, which is CNC control frequency. So the compensation procedure can be applied during axis movement. Using 'SKY-PACS', Maximum 1 axis positioning accuracy was corrected from 5{\mu}m$ to 2{\mu}m$and the squareness error of X-Y table was corrected from 51{\mu}m$/m to below 4{\mu}m$/m. The error compensation under the cutting condition is carried out by ISO10791-7. And the measurement of test-pieces shows that the roundness is corrected rom 8{\mu}m$ to below 5{\mu}m$.

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Effect of Tool Approaching Path on He Shape of Cylindrically Milled Parts (공구 접근 경로가 원통형상의 밀링가공물에 미치는 영향)

  • Kim, Kang
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.3
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    • pp.45-51
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    • 2003
  • Milling process has beer used in aircraft, auto-component and mold industries widely. They need more accurate and precise parts to improve the performance and quality of their products. So, the geometrical form accuracy of the workpiece surface generated by this process is getting more and more important. Generally, the form accuracy is affected by machine conditions, cutting conditions, tool geometry, tool deflection by cutting force and tool path md so on. Even though they are controlled as perfect conditions, it is easily found that there is a line along the axis of a cylindrically milled part. It is presumed that the tool approaching causes this error on milled surface. Thus, the study for investigating the effect of the tool approaching path on the cylindrical surface geometry of the end-milled part is carried out.

Prediction of Form Accuracy during Traverse Grinding of Slender Workpiece Using the Cylindrical Prunge Grinding Data (원통연삭 실험자료를 이용한 트래버스 연삭공정중의 형상예측)

  • 박철우;이상조
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.3
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    • pp.174-183
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    • 2000
  • Non-Parallelism the axial direction occurs during grinding process of long slender shafts. The reason for the axial error is due to elastic deformation of the components, accumulation phenomenon of the grinding and wheel wear during the grinding process. The accumulation phenomenon, the size generation mechanism and the wheel wear process during traverse grinding result in complicated process at each step on the wheel surface. The grinding system stiffness obtained from the stiffness of the center on the tailstock and the workpiece varing according to the relative position of the wheel and the workpiece. Further more, the value of wheel wear increases as the grinding process advances. The above mentioned issues make the shape generation process during traverse grinding quite complicated. This research analyzes the shape generation process in the direction of the work spindle. First, the formulation of the grinding system stiffness was conducted and the simulation analysis method of the traverse grinding was established. Also, a measuring system for assessing the dimensinal accuracy of the workpiece has been developed.

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A Useful Technique for Measuring the 3-dimensional Positioning of a Rotating Object (회전체의 효과적인 3차원 위치오차 측정방법)

  • Lee, Eung-Seok;Wi, Hyeon-Gon;Jeong, Ju-No
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.6
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    • pp.918-924
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    • 1997
  • A method for measuring the accuracy of rotating objects was studied. Rotating axis errors are significant; such as the spindle error of a manufacturing machine which results in the surface roughness of machined work pieces. Three capacitance type displacement sensors were used to measure the rotating master ball position. The sensors were mounted to the three orthogonal points on the spindle axis. The measurement data were analyzed and shown for rotating spindle accuracy, not only for average roundness error but also for spindle volumetric positional error during the revolutions. This method is simple and economical for industrial field use with regular inspection of rotating machines using portable equipment. Measuring and analyzing time using this method takes only a couple of hours. This method can also measure microscopic amplitude and 3-dimensional direction of vibrating objects.

A Study on Tooth Micro-geometry Optimization of Planetary Gear for 5MW Wind Turbine Pitch Drive (5MW 풍력용 피치드라이브의 유성기어 Micro-geometry 최적화에 관한 연구)

  • Lee, In-Bum;Kim, Dong-Young;Xu, Zhe-Zhu;Lee, Do-Young;Lyu, Sung-Ki
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.13 no.1
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    • pp.85-91
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    • 2014
  • The rotation of a spindle unit must be accurate for high-quality machining and to improve the quality of the machine tools. Therefore, the proper measurement of the rotation accuracy and ensuring a proper analysis are very important. Separate processes are necessary because spindle errors and roundness errors associated with the test balls can both factor into the measured rotation error values. We used three methods to discern test ball errors and analyzed which could be deemed as the most proper technique in a test of the rotation accuracy of the main spindle of a machine tool.

The analysis of EDM characteristics for Cu-electrode using LIGA process (LIGA 공정을 이용한 Cu전극의 방전가공 특성 분석)

  • Lee, S.H.;Jung, T.S.;Chang, S.S.;Kim, J.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.383-386
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    • 2007
  • In this study, the analysis was carried out for Electrical Discharge Machining (EDM) characteristics of the Cu electrodes by LIGA process. The shape of electrodes has 324 pins for the cavity of BGA(Ball Grid Array) type test socket mold. BGA test sockets are used in the inspection process of the semi-conductor I.C chip manufacturing. In the work, the machining performance for EDM of the electrodes was analyzed on dimensional accuracy and wear rate. The dimensional accuracy was measured for dimension of the pins, pitch size between the pins and the roundness of corner edge using optical measuring machine.

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Analyses and Measurements of Rotational Accuracy for Journal Shaft in a Scroll Compressor (스크롤 압축기 저어널 회전축의 궤적 계산 및 측정)

  • Park, Sang-Shin;Kim, Gyu-Ha;Lee, Jin-Kab
    • Tribology and Lubricants
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    • v.23 no.3
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    • pp.83-88
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    • 2007
  • This paper presents measurement processes of rotational accuracy and comparison of theoretical values in the main bearing of scroll compressor. The main bearing is a type of oil journal bearing, but it has an axial or helical groove. The generalized coordinate system method, which can handle this groove, is applied to calculate the pressure profile in the journal bearing. The orbits of journal shaft are calculated corresponding to the compressed gas forces and bearing reaction forces. Then, the orbits are measured using three-point method. The results are compared to that from analyses.

Bearing Lobe Profile and Cutting Force Modeling (베어링의 로브형상과 절삭력 모델링)

  • 윤문철;조현덕;김성근
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1998.10a
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    • pp.343-349
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    • 1998
  • A modeling of machined geometry and cutting force was proposed for the case of round shape machining, and the effects of internally machined profile are analyzed and its realiability was verified by the experiments of roundness tester, especially in boring operation in lathe. Also, harmonic cutting force model was proposed with the parameter of specific cutting force, chip width and chip thickness, and in this study, we can see that bored workpiece profile was also mapped into cutting force signal with this model. In general, we can calculated the theoretical lobe profile with arbitrary multilobe. But in real experiments, the most frequently measured numbers are 3 and 5 lobe profile in experiments. With this results, we can predict that these results may be applied to round shape machining such as drilling, boring, ball screw and internal grinding operation with the same method.

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