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RISS 인기검색어
- 검색키워드
- 저자 : 박천홍(Chun-Hong Park) (검색결과 112 건)
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박천홍(Chun Hong Park),황주호(Joo Ho Hwang),조순주(Soon Joo Cho),조창래(Chang Rae Cho) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.11
Design and performance evaluation of a spindle system which was composed of a grinding spindle and a regulating spindle for the centerless grinding of ferrule were performed in this paper. Layout and details of spindle system were designed and hydrostatic bearings for spindles were also designed. Prototype of spindle system was developed and its availabilities to machine the ferrule were discussed using the experimental results on the spindle stiffness of each spindle, loop stiffness, rotational accuracy and thermal characteristics. Loop stiffness of the spindle system was 130 N/㎛, which was enough to machine the ferrule. Rotational accuracies of each spindle were about 0.2 urn at the primary speed of 2,300 rpm(grinding spindle) and 300 rpm (regulating spindle). Temperature rises at the same speed were about 4.4 ~ 4.7 ℃ in the case of grinding spindle and 1.8 ℃ in the case of regulating spindle, which agreed well with the designed value. From these results, it was estimated that the prototype of spindle system had enough performances for the centerless grinding machine to machine the ferrule.
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박천홍(Chun Hong Park),이찬홍(Chan Hong Lee),이후상(Husang Lee) Korean Society for Precision Engineering 2002 한국정밀공학회지 Vol.19 No.6
For improving the motion accuracy of hydrostatic table, corrective machining algorithm is proposed in this paper. The algorithm consists of three main processes. Reverse analysis is performed firstly to estimate rail profile from measured linear and angular motion error, in the algorithm. For the next step, corrective machining information is decided as referring to the estimating rail profile. Finally, motion errors on correctively machined rail are analized by using motion error analysis method proposed in the previous paper. These processes can be iterated until the analized motion errors are satisfied with target accuracy. In order to verify the validity of the algorithm theoretically, motion errors by the estimated rail, after corrective machining, are compared with motion errors by true rail assumed as the measured value. Estimated motion errors show good agreement with assumed values, and it is confirmed that the algorithm is effective to acquire the corrective machining information to improve the accuracy of hydrostatic table.
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전달함수를 이용한 유정압테이블 운동정밀도 해석법의 제안 및 이론적 검증
박천홍(Chun Hong Park),오윤진(Yoon Jin Oh),이찬홍(Chan Hong Lee),홍준희(Joon Hee Hong) Korean Society for Precision Engineering 2002 한국정밀공학회지 Vol.19 No.5
A new model utilizing a transfer function is introduced in the present paper for analyzing motion errors of hydrostatic tables. Relationship between film reaction force in a single hydrostatic pad and form error of a guide rail is derived at various spatial frequencies by finite element analysis, and it is expressed as a transfer function. This transfer function clarifies so-called averaging effect of the oil film quantitatively. For example, it is found that the amplitude of the film reaction force is reduced as the spatial frequency increases or relative width of the pocket is reduced. Motion errors of a multiple pad table is estimated from transfer function, geometric relationship between each pads and form errors of a guide rail, which is named as Transfer Function Method(TFM). Calculated motion errors by TFM show good agreement with motion errors calculated by Multi Pad Method, which is considered entire table as an analysis object. From the results, it is confirmed that the proposed TFM is very effective to analyze the motion errors of hydrostatic tables.
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박천홍(Chun Hong Park),오윤진(Yoon Jin Oh),황주호(Joo Ho Hwang),이득우(Deug Woo Lee) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.6
In order to discuss the availability of hydrostatic guideways driven by the core less linear motor to ultra precision machine tools, a prototype of guideway is designed and tested in this research. A coreless linear DC motor with the continuous force of 156 N and a laser scale with the resulution of 0.01 ㎛ are used as the feeding system. The experiments are performed on the static stiffness, motion accuracy, positioning accuracy, micro step response and variation of velocity. The guideway has the infinite axial stiffness within 50 N of applied load, and by the motion error compensation method using the Active Controlled Capillary, 0.08 ㎛ of linear motion error and 0.1 arcsec of angular motion error are acquired. The guideway also has 0.21 ㎛ of positioning error and 0.09 ㎛ of repeatability, and it shows the stable response against the 0.01 ㎛ resolution step command. The velocity variation of feeding system is less than 0.6%. From these results, it is confirmed that the hydrostatic guideway driven by the coreless linear motor is very useful for the ultra precision machine tools.
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전달함수를 이용한 다공질 공기베어링 스테이지의 운동오차해석
박천홍(Chun Hong Park),이후상(Husang Lee) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.7
In order to analyze the motion errors of the aerostatic stage, it is necessary to consider the influence of the moment variation occurred inside the pads. In this paper, a motion error anaysis method utilizing the transfer functions on the reaction force and moment is proposed, and general characteristics of the transfer functions are discussed. Calculated motion errors by the proposed method show good agreement with the ones calculated by Multi Pad Method, which is considered the entire table as an analysis object. Also, by the introduction of the transfer function of motion errors, which represent the relationship between the spatial frequency components of the rail form error and motion errors, motional characteristics of the porous aerostatic stage can be generalized. In detail, the influence of the spatial frequencies is analyzed quantatively, and the patterns of the insensitive frequencies which almost do not affect the linear motion error or angular motion error according to the rail length ratio and the number of the pad are verified. The relationship between the moment variation occurred inside the pads and the motion errors is also verified together.
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