• Title/Summary/Keyword: 직선베어링

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Analysis of the Motion Accuracy in Linear Motion Bearing Guide (직선베어링 이송계의 운동정밀도 해석)

  • 김경호;이후상;박천홍;김승우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.179-183
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    • 2000
  • This paper is concerned with achieving the high motion accuracy of linear motion bearing guide according to estimate accuracy average effect of bearing. Accuracy average effect can be obtained b analysis the relationship between motion error of the table and spatial frequency of the rail form error. And influences of ball diameter, ball number, and clock length on block motion error and block number on the table motion error are analyzed theoretically. In addition to, a simple experiment is performed in order to verify theoretical result.

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Analysis of the Motion Errors in Linear Motion Guide (직선베어링 안내면의 운동오차 해석)

  • Kim, Kyung-Ho;Park, Chun-Hong;Lee, Hu-Sang;Kim, Seung-Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.5
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    • pp.139-148
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    • 2002
  • Motion errors of linear motion guideway are analyzed theoretically in this paper. For the analysis, an new algorithm predicting motion errors of bearing and guideway is proposed using the Hertz's elastic deformation theory. Accuracy averaging effect can be calculated quantitatively by analyzing relationship between motion errors of guideway and spatial frequency of rail form error. Influences of design parameters on the motion errors including the number of balls, preload, ball diameter, bearing length and the number of bearings are analyzed. As it is difficult to measure the rail form error, experimental results are compared with results analyzed by the equivalent analysis method which evaluate the motion errors of guideway using the measured errors of bearing. From the experimental results, it is confirmed that the proposed analysis method it effective lo analyze the motion errors of linear motion bearing and guideway.

Improvement of Motion Accuracy Using Transfer Function in Linear Motion Bearing Guide (전달함수를 이용한 직선베어링 안내면의 운동정밀도 향상)

  • Kim, Kyung-Ho;Park, Chun-Hong;Lee, Hu-Sang;Kim, Seung-Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.6
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    • pp.77-85
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    • 2002
  • An analysis method which calculates corrective machining information for improving the motion accuracy of linear motion guide Is proposed in this paper. The method is composed of two algorithms. One is the algorithm fur prediction of the motion errors from rail form error. The other is the algorithm for prediction of rail form error from the motion errors of table. Transfer function is utilized in each algorithm, which represents the ratio of bearing reaction force variation to unit magnitude of spatial frequencies of raid from error. As the corrective machining information is acquired from the measured motion errors of table, the method has a merit not to measure rail form error directly. Validity of the method is verified both theoretically and experimentally. By applying the method, linear motion error of test equipment is reduced from 5.97$\mu$m to 0.58$\mu$m, and reduced from 32.78arcsec to 6.21 arcsec in case of angular motion error. From the results, it is confirmed that the method is very effective to improve the motion accuracy of linear motion guide.

A Study on the Fatigue Test and Performance Evaluation for Linear Motion Rolling Bearing (직선운동베어링 성능평가방법의 표준화 및 내구성 시험에 관한 연구)

  • 김태범;김동길;이상조;김익수;이위로;이동규
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1270-1274
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    • 2003
  • The objective of this paper is to introduce the standard of evaluation methods and fatigue test for linear motion rolling bearing. In particular, attention well be given to the list of evaluation and fatigue results in this paper. The life of a linear motion rolling bearing is given by the length of distance covered between the connection parts before the first evidence of fatigue develops in the material of one of the raceways of rolling elements. The main factors that contribute to fatigue failures include: Number of load cycles experienced; Range of stress experienced in each load cycle; Mean stress experienced in each toad cycle; Presence of local stress concentrations.

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Vibration Analysis and Its Application of a Linear Motion Guide Supported by Rolling Ball Bearings (볼 베어링을 이용하는 직선 운동 가이드의 진동 해석 및 응용)

  • Choi Jae Seok;Yi Yong-sub;Kim Yoon Young;Lee Dong Jin;Lee Sung Jin;Yoo Jeonghoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.7 s.238
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    • pp.955-963
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    • 2005
  • This research investigates dynamic characteristics of a linear motion (LM) guide through a experimental result and theoretical analysis. The stiffness in the LM guide is determined by the preloading due to the minus clearance between the ball bearing and the contact surface and it can be derived by Hertzian contact theory and the nonlinear motion of equation. The vibration analysis is performed using Lagrange equations and its result agrees with the experiment result. Using the sensitivity analysis on design parameters such as the contact angles of ball bearings and the eccentricity of mass center, the variation of the natural frequencies can be predicted.

Analysis on the Pressure Rise Characteristics Caused by Movement of Linear and Rotary Stages using Air Bearings in High Vacuum Environment (고진공 환경용 공기베어링이 적용된 직선, 회전스테이지의 구동에 의한 압력증가 특성분석)

  • Kim, Gyung-Ho;Park, Chun-Hong
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.8
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    • pp.112-118
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    • 2009
  • A pressure rise is generated while air bearing stages are moving in high vacuum environment. This study analyzed this pressure rise phenomenon theoretically and verified it experimentally using two different kinds of stages - linear and rotary air bearing stages. Results indicate that the pressure rise was caused by additional leakage resulting from stage velocity, along with adsorption and outgassing of gas molecules from the guide rail surface. Though tilting of the stage due to acceleration and deceleration reached several micrometers, it had a negligible effect on pressure rise because the tilting time was very short. Therefore, a rotary air bearing stage showed much less pressure rise than a linear stage because the rotary stage theoretically has nothing to do with the above causes. Additional leakage caused by stage velocity was inevitable if the stage had movements, but pressure rise caused by adsorption and outgassing could be suppressed by improving the surface quality to reduce real surface area, and by coating the guide rail surface with titanium nitride (TiN) which has less adhesion probability of gas molecules. The results also indicate that the pressure rise increased when the air bearing stage operated under high vacuum conditions.

Micropositioning of a Linear Motion Table with Magnetic Bearing Suspension (자기 베어링으로 지지 되는 직선운동 테이블의 초정밀 위치제어에 관한 연구)

  • 김의석;안형준;장인배;한동철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.466-469
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    • 1995
  • This paper presents a design and performance of the 6 D.O.F linear motion table with a magnetic bearing suspension. The linear positioning of the table with a 150mm stroke is driven by a brushless DC Linear motor and the other attitudes of the stage are controlled by the analog PD controller with magnetic bearing actuators. Each magnetic bearing unit which consists of 3 electromagnets, 3 capacitance probes and 3 backup bearings affords controlled forces by detecting the air gap between the probes and guideways. An integral type capacitance probe amplifier is equipped on the upper plate of the table so that the probe line to the probe amplifier can be shorter therefore the problems due to the stray capacitance and noise can be reduced. Form the pitch-yaw errormeasured by the autocollimator, the vertical and horizont straightness errors of the table are derived that they are maintained below 1.mu. m over 100mm stroke. The positioning accuracy of the linear motion is maintained below 2 .mu. m and the repeatability error is below 1 .mu. m

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A Study on the Deflection of Rail by Bolt Tightening (볼트 체결에 의한 직선운동베어링 레일 변형에 관한 연구)

  • 김태범;이상조;김익수;이위로
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.794-797
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    • 2001
  • The basic design of today s rolling linear guides with rails is outlined in a French patent from 1932, it was not until the early 1970s that linear guides were commercialized. Progress with the numerical control of machine tools led to higher speed and accuracy of machines that exposed limitations of conventional sliding guides in terms of durability and response capability. As a result, rolling guides, having better high-speed performance and greater compatibility with electronics, began to be used widely. This paper examined theoretically and experimentally the influence of rail bolt tightening on the motion accuracy of linear guides. The rail of a linear guide is tightened and fixed to the base component by bolts. Naturally, the rail is an elastic body and the compression force generated by tightening the volts causes its deflection. Compromising motion accuracy, the rail deforms wavily in a longitudinal direction corresponding to the bolt pitch. The relation between rail position and deflection(sinking) amount caused by bolt tightening was analyzed through FEM analysis in this paper.

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The Accuracy Design of LM Guide System in Machine Tools (공작기계 직선 베어링 안내면의 정도 설계에 관한 연구)

  • 김경호;박천홍;송창규;이후상;김승우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.692-695
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    • 2000
  • This paper is concerned with Accuracy Design of LM Guide System in Machine Tools. Elastic deformation of bearing is calculated by Hertz contact theory and motion error of LM block is analyzed. A new algorithm using block stiffness is proposed fur the analysis of motion accuracy of the table. The best advantage of this algorithm is fast analysis speed because it isn't necessary iteration processes for satisfying equilibrium equation of the table. Motion errors of the table analyzed under artificial form error of rail theoretically and experimentally. Only one of two rails is bent by putting a thickness gauge into horizontal direction. This form error of rail is measured by gap sensor against the other rail. Then, motion errors of the table are predicted by proposed new algorithm theoretically and measured by laser interferometer. Measurements are carried out by changing the preload and thickness. The results show that the table motion errors are reduced from 1/2 to 1/60 times than form error of rail according to its height and width. And the effect of preloading is almost negligible.

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Study on the Air Bearings with Actively Controllable Magnetic Preloads for an Ultra-precision Linear Stage (초정밀 직선 이송계용 능동 자기예압 공기베어링에 관한 연구)

  • Ro, Seung-Kook;Kim, Soo-Hyun;Kwak, Yoon-Keun;Park, Chun-Hong
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.6
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    • pp.134-142
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    • 2008
  • In this paper, we propose a precise linear motion stage supported by magnetically preloaded air bearings. The eight aerostatic bearings with rectangular carbon porous pads were located only one side of vertical direction under the platen where four bearings are in both sides of horizontal direction as wrap-around-design, and this gives simpler configuration than which constrained by air bearings for all direction. Each of the magnetic actuators has a permanent magnet generating static magnetic flux far required preload and a coil to perturb the magnetic farce resulting adjustment of air- bearing clearance. The characteristics of porous aerostatic bearing are analyzed by numerical analysis, and analytic magnetic circuit model is driven for magnetic actuator to calculate preload and variation of force due to current. A 1-axis linear stage motorized with a coreless linear motor and a linear encoder was designed and built to verify this design concept. The load capacity, stiffness and preload force were examined and compared with analysis. With the active magnetic preloading actuators controlled with DSP board and PWM power amplifiers, the active on-line adjusting tests about the vertical, pitching and rolling motion were performed. It was shown that motion control far three DOF motions were linear and independent after calibration of the control gains.