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3축 마이크로 공작기계용 자기예압 공기베어링 스테이지의 정, 동적 특성
노승국,Kornel F. Ehmann,Yoon, Hyung-Suk,박종권 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-
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 mm². 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 9N/μm where Y stiffness of Z column is much smaller as 1N/μm because of the large moment generated by Y force on the column.
Error modeling for sensitivity analysis and calibration of the tri-pyramid parallel robot
Lee, Sungcheul,Zeng, Qiang,Ehmann, Kornel F. Springer-Verlag 2017 INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TE Vol.93 No.1
<P>Developments in machine tooling technology are driven by a demand for high-precision machining of various materials. However, high-precision machining using a kinematic model with nominal values is associated with inaccuracy as the machine errors are not accounted for. Therefore, it is important to precisely determine the machine error factors to produce an accurate error model. Complex models that use iterative calculation in the calibration process are time-consuming and resource-intensive. In this paper, a simplified error model was applied to a translational parallel tri-pyramid robot with three degrees of freedom (DOF). The sources of kinematic error were joint errors, kinematic parameter errors, and actuator control errors; 90 errors were identified in total. The full error model was defined using a linearized homogeneous transformation matrix (HTM) and the Denevit-Hartenberg (DH) parameters. The 27 dominant error sources affecting the accuracy of the platform position were selected by a sensitivity analysis method. After the error reduction model based on these sources was established, the calibration was performed by simulation. The calibration simulation results suggest that the model accuracy could be improved from 0.85 to 0.26 mm.</P>
A Three-axis Translation Stage Using Opposing Wedges with Error Compensation
김경호,노승국,박종권,Kornel Ehmann 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.
We describe the development of a three-axis translation stage using wedges and its motion error compensation. The threeaxis stage uses three wedges and is capable of translation in the vertical and longitudinal directions by controlling the horizontal separation of two opposing wedges. An independent linear translation stage is used to achieve displacement along the third axis. Compensation for straightness and positioning errors is achieved using the combined motion of the two opposing wedges and the motion of an independent linear stage. The straightness error in the vertical and horizontal directions through the longitudinal axis was 0.83 μm and 1.65 μm, respectively, before compensation and 0.22 μm and 0.29 μm with error compensation. The positioning error through the longitudinal axis was reduced from 8.96 μm to 0.85 μm.
3축 마이크로 공작기계용 자기예압 공기베어링 스테이지의 정, 동적 특성
노승국(Seung-Kook Ro),Kornel F. Ehmann,Hyung-Suk Yoon,박종권(Jong-Kweon Park) 한국생산제조학회 2005 한국생산제조시스템학회 학술발표대회 논문집 Vol.2005 No.5
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 200×200㎟. 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/㎛ where Y stiffness of Z column is much smaller as 1 N/㎛ because of the large moment generated by Y force on the column.
Feasibility of Using Copper(II)Oxide for Additive Manufacturing
Yunho Yang,Christopher Yarka,Jian Cao,Kornel Ehmann 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
Additive manufacturing, in spite of its ever wider application range, is still plagued by issues ranging from accuracy to surface finish. In this study, to address the latter issue, the feasibility of using Copper(II)Oxide powder with a polymer binder deposited through aFused Deposition Modeling (FDM) 3D printing technique is explored. In particular, the post processing of the green componentsthrough a newly developed furnace sintering process is investigated. The properties of the generated test samples were assessed byusing Scanning Electron Microscope (SEM), surface roughness and optical analysis methods in addition to properties of the sinteredsamples through Energy Dispersive X-Ray Spectrometry (EDS).
Retraction Note: Feasibility of Using Copper(II)Oxide for Additive Manufacturing
Yunho Yang,Christopher Yarka,Jian Cao,Kornel Ehmann 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.12
Additive manufacturing, in spite of its ever wider application range, is still plagued by issues ranging from accuracy to surface finish. In this study, to address the latter issue, the feasibility of using Copper(II)Oxide powder with a polymer binder deposited through a Fused Deposition Modeling (FDM) 3D printing technique is explored. In particular, the post processing of the green components through a newly developed furnace sintering process is investigated. The properties of the generated test samples were assessed by using Scanning Electron Microscope (SEM), surface roughness and optical analysis methods in addition to properties of the sintered samples through Energy Dispersive X-Ray Spectrometry (EDS).
A Three-axis Translation Stage Using Opposing Wedges with Error Compensation
Khim, Gyung-Ho,Ro, Seung-Kook,Park, Jong-Kweon,Ehmann, Kornel 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.3
We describe the development of a three-axis translation stage using wedges and its motion error compensation. The three-axis stage uses three wedges and is capable of translation in the vertical and longitudinal directions by controlling the horizontal separation of two opposing wedges. An independent linear translation stage is used to achieve displacement along the third axis. Compensation for straightness and positioning errors is achieved using the combined motion of the two opposing wedges and the motion of an independent linear stage. The straightness error in the vertical and horizontal directions through the longitudinal axis was 0.83 ${\mu}m$ and 1.65 ${\mu}m$, respectively, before compensation and 0.22 ${\mu}m$ and 0.29 ${\mu}m$ with error compensation. The positioning error through the longitudinal axis was reduced from 8.96 ${\mu}m$ to 0.85 ${\mu}m$.