• Title/Summary/Keyword: Bearing error

Search Result 284, Processing Time 0.034 seconds

Rotational Characteristics of High Precision Spindle Unit with Ball-Hydrostatic Bearing (볼-유정압 복합베어링을 갖는 고정밀 주축의 회전특성에 관한 연구)

  • 이찬홍;이후상
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2000.05a
    • /
    • pp.663-667
    • /
    • 2000
  • The spindle unit is core parts in high precision machine tools. Diverse static and dynamic charateristics of spindle unit are needed for special purpose of machine tools. Specially, high damping ability may be very useful to high precision and high speed spindle unit. But commercial bearing system has very low damping value and high stiffness. In this paper, the combined bearing system with ball-hydrostatic bearing is suggested for high damping spindle unit. The suggested bearing system has 30% damping ability more than general ball bearing's. The average rotational accuracy of spindle with combined bearing in working speed is 24% better than with ball bearing. The unbalance rotating experiment in spindle show that rotating error with combined bearing is only half value of with ball bearing.

  • PDF

Rotational Accuracy Measurement of Scroll Compressor with D-type Sectional Shaft

  • Park, Sang-Shin;Kim, Gyu-Ha;Lee, Jin-Kab
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
    • /
    • 2002.10b
    • /
    • pp.125-127
    • /
    • 2002
  • This paper presents the measurement process of the rotational accuracy and the comparison with the theoretical results in the main bearing of scroll compressor. The main bearing is cylindrical oil proceeding bearing, but there are straightly cut used for oil supply. Therefore the roundness error is not a negligible quantity compared with the rotational accuracy. For this reason, three-point method is used in the experiment. The result of three-point method coincides with the theoretical value. So if the theory in this paper is used to the bearing design of scroll compressor, the efforts for testing and designing can be reduced.

  • PDF

Runout Control of a Magnetically Suspended Grinding Spindle (자기베어링으로 지지된 연삭 스핀들의 런아웃 제어)

  • 노승국;경진호;박종권;최언돈
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2000.05a
    • /
    • pp.1011-1015
    • /
    • 2000
  • In this paper, the case studies of reducing rotational errors is theoretically done for a grinding spindle with an active magnetic bearing system. The rotational errors acting on the magnetic bearing spindle are due to mass unbalance of rotor, runout, grinding excitation and unmodeled nonlinear dynamics of electromagnets. The adaptive feedforward method based on LMS algorithm is discussed to compensate output and input disturbances, and investigated its effectiveness by numerical simulation. The feedforward control reduced external excitation and rotational error for specified frequency. The interpolation method using impulse function for cancelling the electrical 'uncut is studied. These methods show their effectiveness for the rotational accuracy of the improving magnetic bearing spindle through some simulation results of the rotational error decreased by them.

  • PDF

A Study on Improvement of the Ship's Bearing Information using GPS (GPS를 이용한 선박의 방위정보 향상에 관한 연구)

  • Ko Kwang-Soob;Choi Chang-Mook
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.9 no.3
    • /
    • pp.528-533
    • /
    • 2005
  • The purpose of the study is to develop ship's bearing sensor using GPS receiver which can play a role as a ship's secondary compass. In this research, two GPS receivers are used to determine the bearing in real time. Then we investigated the bearing accuracy associated with the error pattern of two GPS receivers. Especially, the results are as follows the investigation on the system design of GPS-Compass, the modeling to compute heading of sailing, the analysis on bearing accuracy with the error pattern, the defining possibility to play a role as a ship's secondary compass.

Prediction of Ultimate Bearing Capacity of Soft Soils Reinforced by Gravel Compaction Pile Using Multiple Regression Analysis and Artificial Neural Network (다중회귀분석 및 인공신경망을 이용한 자갈다짐말뚝 개량지반의 극한 지지력 예측)

  • Bong, Tae-Ho;Kim, Byoung-Il
    • Journal of the Korean Geotechnical Society
    • /
    • v.33 no.6
    • /
    • pp.27-36
    • /
    • 2017
  • Gravel compaction pile method has been widely used to improve the soft ground on the land or sea as one of the soft ground improvement technique. The ultimate bearing capacity of the ground reinforced by gravel compaction piles is affected by the soil strength, the replacement ratio of pile, construction conditions, and so on, and various prediction equations have been proposed to predict this. However, the prediction of the ultimate bearing capacity using the existing models has a very large error and variation, and it is not suitable for practical design. In this study, multiple regression analysis was performed using field loading test results to predict the ultimate bearing capacity of ground reinforced by gravel compaction pile, and the most efficient input variables are selected through evaluation of error by leave one out cross validation, and a multiple regression equation for the prediction of ultimate bearing capacity was proposed. In addition, the prediction error was evaluated by applying artificial neural network using the selected input variables, and the results were compared with those of the existing model.

Accuracy Simulation of Precision Rotary Motion Systems (회전운동 시스템의 정밀도 시뮬레이션 기술)

  • Hwang, Joo-Ho;Shim, Jong-Youp;Hong, Seong-Wook;Lee, Deug-Woo
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.28 no.3
    • /
    • pp.285-291
    • /
    • 2011
  • The error motion of a machine tool spindle directly affects the surface errors of machined parts. The error motions of the spindle are not desired errors in the three linear direction motions and two rotating motions. Those are usually due to the imperfect of bearings, stiffness of spindle, assembly errors, external force or unbalance of rotors. The error motions of the spindle have been needed to be decreased to desired goal of spindle's performance. The level of error motion is needed to be estimated during the design and assembly process of the spindle. In this paper, the estimation method for the five degree of freedom (5 D.O.F) error motions of the spindle is suggested. To estimate the error motions of the spindle, waviness of shaft and bearings, external force model was used as input data. And, the estimation models are considering geometric relationship and force equilibrium of the five degree of the freedom. To calculate error motions of the spindle, not only imperfection of the shaft, bearings, such as rolling element bearing, hydrostatic bearing, and aerostatic bearing, but also driving elements such as worm, pulley, and direct driving motor systems, were considered.

Experimental Investigation of the Effect of Lead Errors on Helical Gear and Bearing Vibration Transmission Characteristics

  • Park, Chan-Il;Lee, Jang-Moo
    • Journal of Mechanical Science and Technology
    • /
    • v.16 no.11
    • /
    • pp.1395-1403
    • /
    • 2002
  • The characteristics of gear meshing vibration undesgo change as the vibration is transmitted from the gear to the housing. Therefore, vibration transmission characteristics of helical gear systems must be understood before the effective methods of reducing gear noise can be found. In this work, using a helical gear with different lead errors, the gear vibration in the rotational direction and the bearing vibration are measured. The frequency characteristics of gear and bearing vibration are investigated and a comparson is also provided.

A Study on the Characteristics of an Externally Pressurized Conical Gas Bearing (외부가압 원추형 공기베어링의 특성에 관한 연구)

  • 박상신;한동철
    • Tribology and Lubricants
    • /
    • v.7 no.1
    • /
    • pp.35-39
    • /
    • 1991
  • The performance of the ultra-precision machine tools depends on the steady state characteristics of the main spindle bearings. For excluding the effect of machining error with perpendicularity, conical or spherical bearing has been used. In this paper, steady analysis of the externally pressurized conical gas bearing for ultraprecision is carried out based on the direct numerical method with assumption of point source. As a result of theoretical analysis, design parameters for optimal condition of conical gas bearing are' presented in dimensionless form.

Dynamic Characteristics of an Externally Pressurized Conical Gas Bearing (외부가압 원추형 공기 베어링의 동특성에 관한 연구)

  • 박상신;김우정;김종원;한동철
    • Tribology and Lubricants
    • /
    • v.8 no.1
    • /
    • pp.78-83
    • /
    • 1992
  • For excluding the effect of machining error such as perpendicularity, conical and spherical bearing has been used. In this paper, dynamic characteristics of the externally pressurized conical gas bearing for untraprecision main spindle is carried out based on the direct numerical method with assumption of point source. As a result of theoretical analysis, it is verified that coupled stiffness and damping exist and new design parameters for optimal condition of conical gas bearing are presented in dimensionless form.

Nonlinear Analysis of Gear Driving System due to Misalignment (정렬불량에 의한 기어구동계 비선형 해석)

  • Lee, B. H.;Park, Y. S.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2002.11a
    • /
    • pp.311.2-311
    • /
    • 2002
  • Even through the problem of misalignment is of great importance, not much work has been reported in the literature on the effect of misalignment on the vibrations of the gear-bearing systems. Therefore, the nonlinear dynamic characteristics of the gear driving system due to misalignment are investigated in this work. Transmission error for helical gear and bearing nonlinear stiffness is calculated. (omitted)

  • PDF