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고속 주축베어링의 볼 접촉각 변동을 고려한 주축 설계공차
이찬홍,Lee, Chan-Hong 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.5
Angular contact ball bearings in a high speed spindles are under the extreme conditions, such as high temperature, big centrifugal force and thrust cutting forces. So, the assembly contacts between spindle shaft and inner ring bearings, bearing housing and outer ring of bearings are occasionally unstable at high speed revolution. Furthermore, the ball contact angle of a bearing, which influence stiffness and lifetime of bearings, are changed according to loads and rotational speed. To analyze internal forces of a bearing under high speed revolution, the ball contact are calculated using nonlinear equations in consideration of rotational speed, thrust loads and raceway form. Diameter increase of inner and outer ring by influence factors, such as internal forces to inner and outer ring, centrifugal force and temperature of inner and outer rings are calculated to establish stable state in bearing assembly in high speed spindle. Finally, contribution ratio of influence factor to assembly design tolerance of inner and outer rings are shown and the stable assembly design tolerance are proposed.
고속 회전시 베어링 강성강하를 고려한 주축 유니트의 최적화
이찬홍,Lee, Chan-Hong 한국생산제조학회 2010 한국생산제조학회지 Vol.26 No.1
Radial stiffness of angular contact ball bearings are decreased remarkably at high speed revolution, because the inner and outer ball contact angle with races arc changed under the ball centrifugal forces at high speed. In the past, the optimizations of spindle units were done under the assumption of unchanged bearing stiffness for the whole speed range. But the bearing stiffness is changed and the dimension of optimum spindle is also changed with speed. In the design phase, only one model of many optimum spindle models with speed should be selected. As optimization criterion, the area of transfer function at spindle nose is proposed to estimate simply and accurately improvement of dynamic characteristics in spindle units. Finally, according to many analyses of diverse spindle models with decreased bearing stiffness, the spindle with shorter bearing span is better than longer bearing span from the viewpoint of dynamic characteristics.
고속 주축베어링의 볼 접촉각 변동을 고려한 주축 설계공차
이찬홍(Chan Hong Lee) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.5
Angular contact ball bearings in a high speed spindles are under the extreme conditions, such as high temperature, big centrifugal force and thrust cutting forces. So, the assembly contacts between spindle shaft and inner ring of bearings, bearing housing and outer ring of bearings are occasionally unstable at high speed revolution. Furthermore, the ball contact angle of a bearing, which influence stiffness and lifetime of bearings, are changed according to external loads and rotational speed. To analyze internal forces of a bearing under high speed revolution, the ball contact angles are calculated using nonlinear equations in consideration of rotational speed, thrust loads and raceway form. Diameter increase of inner and outer ring by influence factors, such as internal forces to inner and outer ring, centrifugal force and temperature of inner and outer rings are calculated to establish stable state in bearing assembly in high speed spindle. Finally, contribution ratio of influence factor to assembly design tolerance of inner and outer rings are shown and the stable assembly design tolerance are proposed.
Lead Frame용 캠 프레스의 이송장치 고속화 설계
이찬홍(Chan Hong Lee),임선종(Sun Jong Lim) 한국생산제조학회 2007 한국생산제조시스템학회 학술발표대회 논문집 Vol.2007 No.10
The high speed feeding units, that are known generally weak points at the high speed semiconductor press are developed to increase feeding velocity up to 155%. The new designed feeding units has the performance, feeding velocity 170spm, positioning accuracy under 100㎛, decrease of link joint in feeding units, overload monitoring system with high sensitivity.
이찬홍(Chan Hong Lee) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4
Volumetric errors of parallel kinematic mechanism are influenced seriously by the units assembly errors and parts form errors in comparison with cartesian machine tools. But the measure of volumetric errors in PKM to analyze error source and level is a difficult task. In this paper, to get theoretical independent influence level of each feeding unit errors on volumetric errors, the 3D compliance model of PKM is configured and the motion software is used to obtain circular trajectories of tool center point in PKM. The total volumetric errors by units weight, assembly errors and structure joint stiffness can be calculated.
고속 회전시 베어링 강성강하를 고려한 주축 유니트의 최적화
이찬홍(Chan Hong Lee) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.6
Radial stiffness of angular contact ball bearings are decreased remarkably at high speed revolution, because the inner and outer ball contact angle with races are changed under the ball centrifugal forces at high speed. In the past, the optimizations of spindle units were done under the assumption of unchanged bearing stiffness for the whole speed range. But the bearing stiffness is changed and the dimension of optimum spindle is also changed with speed. In the design phase, only one model of many optimum spindle models with speed should be selected. As optimization criterion, the area of transfer function at spindle nose is proposed to estimate simply and accurately improvement of dynamic characteristics in spindle units. Finally, according to many analyses of diverse spindle models with decreased bearing stiffness, the spindle with shorter bearing span is better than longer bearing span from the viewpoint of dynamic characteristics.