• Title/Summary/Keyword: Air Bearing Stage

Search Result 47, Processing Time 0.034 seconds

Static and Dynamic Characteristics of Magnetically Preloaded Air Bearing Stage for a 3-Axis Micro-Machine Tool (3축 마이크로 공작기계용 자기예압 공기베어링 스테이지의 정, 동적 특성)

  • Ro Seung-Kook;Ehmann Kornel F.;Yoon Hyung-Suk;Park Jong-Kweon
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
    • /
    • 2005.05a
    • /
    • pp.468-472
    • /
    • 2005
  • In this paper, the static and dynamic stiffness of the air bearing stage for micro-micro machine tool are examined experimentally. For stiffness and precision concerns, air bearing stages are adapted for 3-axis micro-milling machine which is size of $200x200\;mm^2$. The air bearings in the stage are preloaded by permanent magnets to achieve desired bearing clearance and stiffness for vertical direction. As the stiffness of the air bearing is primary interests, static stiffness test were performed on XY stage in Z direction and Z column in Y direction. Dynamic test were performed on XY stage and Z column, respectively. Both static and dynamic tests were performed in different air pressure conditions. The vertical stiffness of XY stage is about 9 N/ pm where Y stiffness of Z column is much smaller as $1\;N/{\mu}m$ because of the large moment generated by Y force on the column.

  • PDF

Effect of the Pocket Depth on the Hammering Behavior of an Air Bearing Stage (포켓의 깊이가 공기 베어링 스테이지의 햄머링 현상에 미치는 영향)

  • Lee, Chun Moo;Kim, Gyu Ha;Park, Sang Joon;Hwang, Gyu-Jin;Park, Sang-Shin
    • Tribology and Lubricants
    • /
    • v.37 no.4
    • /
    • pp.129-135
    • /
    • 2021
  • An air-bearing stage uses externally pressurized air as the lubricant between the stage and the rail. The supporting force generated by the supplied air makes the stage rise and move smoothly with extremely low friction. Mechanical contacts rarely happen, the bearing surfaces do not produce wear particles, and dust is not generated. It also has the advantage of having low energy loss and high precision. Because of its advantages, an air-bearing stage is used in several types of machines that require high precision. In this article, the effect of the pocket depth on the hammering phenomena of the air bearing is studied. An analysis program is developed to calculate the dynamic behavior of the stage by solving the Reynolds equation between the stage and the guideway and the equations of motion on the stage. The acceleration, constant movement, and deceleration are applied to the stage. The stage is modeled as a five-degree-of-freedom system. In the course of the dynamic behavior, the hammering phenomena occur under some special conditions. The deeper the pocket, the more unstable the behavior of the stage, and air hammering occurs when it exceeds a certain depth. In addition, the higher the supply pressure, the more unstable the behavior of the stage. However, hammering occurs even with a shallow pocket depth. Other conditions that affect the hammering phenomena are calculated and discussed.

A Miniature Air-Bearing Positioning Stage with a Magnet-Moving Linear Motor (영구자석 이동형 선형 모터를 가진 초소형 공기베어링 스테이지)

  • Ro, Seung-Kook;Park, Jong-Kweon
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.24 no.8 s.197
    • /
    • pp.89-96
    • /
    • 2007
  • In this paper, a new air bearing stage with magnetic preload and a linear motor has been developed for the small precision machine systems. The new air bearing stage is unique in the sense that permanent magnets attached bottom of the iron core of table are used not only for preloading air bearings in vertical direction but also for generating thrust force by current of the coil at base. The characteristics of air bearings using porous pads were analyzed with numerical method, and the magnetic circuit model was derived for linear motor for calculating required preload force and thrust force. A prototype of single axis miniature stage with size of $120(W){\times}120(L){\times}50(H)\;mm^3$ was designed and fabricated and examined its performances, vertical stiffness, load capacity, thrust force and positioning resolution.

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
    • /
    • v.26 no.8
    • /
    • pp.112-118
    • /
    • 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.

Development of a Miniature Air-bearing Stage with a Moving-magnet Linear Motor

  • Ro, Seung-Kook;Park, Jong-Kweon
    • International Journal of Precision Engineering and Manufacturing
    • /
    • v.9 no.1
    • /
    • pp.19-24
    • /
    • 2008
  • We propose a new miniature air-bearing stage with a moving-magnet slotless linear motor. This stage was developed to achieve the precise positioning required for submicron-level machining and miniaturization by introducing air bearings and a linear motor sufficient for mesoscale precision machine tools. The linear motor contained two permanent magnets and was designed to generate a preload force for the vertical air bearings and a thrust force for the stage movement. The characteristics of the air bearings, which used porous pads, were analyzed with numerical methods, and a magnetic circuit model was derived for the linear motor to calculate the required preload and thrust forces. A prototype of a single-axis miniature stage with dimensions of $120\;(W)\;{\times}\;120\;(L)\;{\times}\;50\;(H)\;mm$ was designed and fabricated, and its performance was examined, including its vertical stiffness, load capacity, thrust force, and positioning resolution.

Leakage Analysis of Air Bearing for Vacuum Environment (진공환경용 공기베어링의 Leakage 해석)

  • 김경호;박천홍;이후상;김승우
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2004.10a
    • /
    • pp.912-915
    • /
    • 2004
  • A vacuum environment is very important for NGL(Next Generation Lithography) apparatuses such as EUVL(Extreme Ultra Violet Lithography) or EPL(Electron Projection Lithography) and so on. The performance of these systems is dominated by vacuum level of processing and positioning accuracy of a stage. So, ultra-precision stage usable in a high vacuum level is needed for the improved performance of these devices. In contrast to atmospheric condition, a special attention must be paid to guide bearing, actuator and other elements. In this paper, air bearing is adopted because of its very high motional accuracy. So, air bearing is designed to be vacuum compatible using differential exhaust method, which prevents air from entering into vacuum chamber. For this, leakage analysis is performed theoretically and verified from experiment.

  • PDF

Effect of Shape Error of an Air Stage on Motion Precision (공기 스테이지의 형상 오차가 운동정밀도에 미치는 영향)

  • Ryu, Daewon;Lee, Jae Hyeok;Park, Sang-Shin;Kim, Gyu Ha
    • Tribology and Lubricants
    • /
    • v.36 no.2
    • /
    • pp.68-74
    • /
    • 2020
  • In this study, the effect of the shape error of a guideway on the movement of a stage that uses an air bearing is analyzed. The shape error of moving parts supported by the air bearing is known not to affect the vibrations of moving parts as much as the magnitude of the shape error. This is called the "averaging effect." In this study, the effect of shape error on a guideway, as well as the averaging effect of an air-bearing system, is analyzed theoretically using a dynamic-analysis program. The dynamic-analysis program applies a commercially available code in COMSOL and solves the Reynolds equation between the stage and the guideway, along with the equation of motion of the stage. The stage is modeled as a two-degree-of-freedom system. The shape error is applied to the film thickness function in the form of a sine wave. The stage movement is analyzed using the fast Fourier transform process. The eccentricity and tilting are found to be proportional to the amplitude of the shape error of the guideway. Stage vibrations are less than 10% of the amplitude of the shape error on the guideway. This means that the averaging effect of the air bearing is verified quantitatively. Moreover, if the air supply position matches the shape error in the guideway, there is a notable change in eccentricity and tilting.

Study on the Linear Air Bearing Stage with Actively Controllable Magnetic Preload (초정밀 스테이지를 위한 능동형 자기예압 공기베어링에 관한 연구)

  • Ro S.K.;Park C.H.;Kim S.H.;Kwak Y.K.
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2006.05a
    • /
    • pp.135-136
    • /
    • 2006
  • A precise linear motion stage supported by magnetically preloaded air bearings is introduced where preloading magnetic actuators are combined with permanent magnets and coils to adjust air bearing clearance by controlling magnetic force actively. Each of the magnetic actuators has a permanent magnet generating nominal magnetic flux for required preload and a coil to perturb the magnetic force 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 nominal preload and variation of force due to current. A 1-axis linear stage motorized with a coreless linear motor and a linear encoder is built for verifying this design concept. 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, and the result shows very good linearity.

  • PDF

Effect of the Acceleration and Deceleration on the Dynamic Characteristics of an Air Stage (에어 스테이지의 동적 특성에 미치는 가속도 및 감속도의 영향)

  • Park, Sang Joon;Lee, Jae Hyeok;Park, Sang-Shin;Kim, Gyu Ha
    • Tribology and Lubricants
    • /
    • v.36 no.1
    • /
    • pp.39-46
    • /
    • 2020
  • Air stages are usually applied to precision engineering in sectors such as the semiconductor industry owing to their excellent performance and extremely low friction. Since the productivity of a semiconductor depends on the acceleration and deceleration performance of the air stage, many attempts have been made to improve the speed of the stage. Even during sudden start or stop sequences, the stage should maintain an air film to avoid direct contact between pad and the rail. The purpose of this study is to quantitatively predict the dynamic behavior of the air stage when acceleration and deceleration occur. The air stage is composed of two parts; the stage and the guide-way. The stage transports objects to the guideway, which is supported by an externally pressurized gas bearing. In this study, we use COMSOL Multiphysics to calculate the pressure of the air film between the stage and the guide-way and solve the two-degree-of-freedom equations of motion of the stage. Based on the specified velocity conditions such as the acceleration time and the maximum velocity of stage, we calculate the eccentricity and tilting angle of the stage. The result shows that the stiffness and damping of the gas bearing have non-linear characteristics. Hence, we should consider the operating conditions in the design process of an air stage system because the dynamic behavior of the stage becomes unstable depending on the maximum velocity and the acceleration time.

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
    • /
    • v.25 no.6
    • /
    • pp.134-142
    • /
    • 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.