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Fatigue Life Analysis for Angular Contact Ball Bearing with Angular Misalignment
배규현(Gyu-Hyun Bae),통반칸(Van-Canh Tong),홍성욱(Seong-Wook Hong) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.1
Angular misalignment has a significant effect on the characteristics of angular contact ball bearings (ACBBs). This paper presents an analysis of fatigue life for ACBBs subjected to angular misalignment. A simulation model is developed with de Mul’s bearing model and the ISO basic reference rating life model. Simulation is performed to calculate the life of the ACBBs subjected to angular misalignment. The numerical results show that angular misalignment influences the load distribution significantly, thus reducing the bearing rating life. The fatigue life of ACBBs is decreased by angular misalignment regardless of axial preload, external radial load and rotational speed. The results show that angular misalignment should be maintained at less than 1mrad for ACBBs.
각접촉 볼베어링으로 지지된 스핀들의 정렬오차에 의한 동특성 변화 해석
배규현(Gyu-Hyun Bae),홍성욱(Seong-Wook Hong),윤영석(Young-Seok Yoon) 한국생산제조학회 2014 한국생산제조학회지 Vol.23 No.4
This paper presents the dynamic modeling and analysis results for a spindle supported by angular contact ball bearings (ACBBs) subjected to angular misalignment. Although ACBBs are widely used in spindle systems, their characteristics in regard to angular misalignment have rarely been investigated. A simulation program was developed to calculate the dynamic characteristics of a simple spindle model that is supported by angular contact ball bearings subjected to angular misalignment. Angular misalignment is shown to introduce anisotropy into the angular contact ball bearings and then split the natural frequencies in spindles. Simulations were also performed to show the possibility of evaluating bearing misalignment using natural frequency measurements.
압전구동기 히스테리시스를 고려한 마이크로스테이지 모델링 및 특성 개선
배규현(Gyu-Hyun Bae),최수창(Soo-Chang Choi),이득우(Deng-Woo Lee),홍성욱(Seong-Wook Hong) 한국생산제조학회 2009 한국공작기계학회 추계학술대회논문집 Vol.2009 No.-
Precise stages often employ piezoactuators of which inherent hysteretic characteristics cause a nonlinear behavior to the stages. This paper presents a dynamic model for a micro-stage with a displacement magnification mechanism which includes the hysterisis model for the piezoactuators. The previous study reveals that the proposed micro-stage provides large displacement but it is subjected to severe residual vibration because of little damping engaged in the displacement magnification mechanism. Although the input shaping method is useful for reducing such residual vibration, it proves to be ineffective when a large input is applied to the system. The present paper investigates the dynamic characteristics of the system of which piezoactuator characteristics are included. The simulation results show that the actuator hysterisis can change the dynamic characteristics of the system and the employment of robust input shapers is able to compensate the performance deterioration of input shaping due to the hysterisis.
크레인의 정밀한 정지와 잔류진동 억제를 위한 개선된 입력 성형기법
배규현(Gyu-Hyun Bae),홍성욱(Seong-Wook Hong) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.7
Industrial cranes are indispensable equipment in heavy industry. However, unwanted vibrations in cranes often cause accidents. Input shaping is widely accepted as a useful tool for removing residual vibration in cranes. A unity magnitude zero vibration (UMZV) input shaper is often used for cranes driven by on?off-type motors. However, although a UMZV input shaper minimizes residual vibration, the input shaper cannot prevent the crane from moving slightly further than expected from the original command. This paper describes an improved method of input shaping that can compensate for position inaccuracies, as well as remove the residual vibration of cranes. Experiments were performed to validate the proposed input-shaping method, illustrated through numerical simulations.
회전속도에 따른 고속 스핀들의 돌출량 예측에 관한 연구
배규현(Gyu-Hyun Bae),이찬홍(Chan-Hong Lee),황주호(Jooho Hwang),홍성욱(Seong-Wook Hong) Korean Society for Precision Engineering 2012 한국정밀공학회지 Vol.29 No.6
This paper presents an estimation procedure for axial displacement in spindle equipped with angular contact ball bearings due to rotational speed. High-speed spindle-bearing system experiences axial displacement due to thermal expansion and rotational speed-dependent characteristics of angular contact ball bearings. This paper deals with the axial displacement caused by the rotational speed-dependent effects such as centrifugal force and gyroscopic moments. To this end, a bearing dynamic model is established that includes all the static and dynamic properties of angular contact ball bearing. An analytical formula to calculate the axial displacement based on contact angles between ball and races is derived to discuss the physics regarding the axial displacement in spindle. The proposed dynamic model is compared with a reference and a commercial program. Numerical examples are presented to show the effects of centrifugal force and gyroscopic moment on the axial displacement. The proposed model is also validated with an experimental result.
탄성 회전체 베어링 계의 불균형 응답 저감을 위한 동흡진기 개발
유태규(Tae-Gyu Yu),배규현(Gyu-Hyun Bae),김길환(Kil-Hwan Kim),홍성욱(Seong-Wook Hong) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.1
This paper presents a novel dynamic vibration absorber (DVA) to suppress the unbalance response of flexible rotor-bearing systems. The DVA unit consists of two DVAs, an adapter to place the DVAs and an adapter frame to locate the adapter. The essential feature of the proposed DVA unit is to place itself on any desirable location of the shaft without disassembling the rotor-bearing system under consideration. A simulation with a 3D element based commercial rotor dynamic software is made to test the possibility of the proposed DVA on the suppression of unbalance response in rotor-bearing systems. Experiments are performed to validate the proposed DVA unit. The simulation and experiments show that the proposed DVA unit is very effective to suppress the unbalance response in rotor-bearing system at designated rotational speeds of interest.
중력에 의해 진동하는 2단 축방향 전개 보의 유한요소 모델링
윤원상(Won-Sang Yun),배규현(Gyu-Hyun Bae),범희락(Hee-Rak Beom),홍성욱(Seong-Wook Hong) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.2
Multi-stage deploying beams are useful for transporting parts or products handling in production lines. However, such multi-stage beams are often exposed to unwanted vibration due to the presence of their flexibility and time-varying properties. This paper is concerned with dynamic modeling and analysis of 2-stage axially deploying beams under gravity by using the finite element method. A variable domain finite element method is employed to develop the dynamic model. A rigorous method to account for engagement of two-stage beams during the deploying procedure is introduced by breaking the entire domain into three variable domains. Several deploying strategies are tested to analyze the residual vibrations. Several examples are illustrated to investigate the self-induced damping and the effects of deploying strategy on the vibrations.
Dynamic Analysis of Spindle Supported by Multiple Bearings of Different Types
Van-Canh Tong(통반칸),Gyu-Hyun Bae(배규현),Seong-Wook Hong(홍성욱) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.2
This paper presents a dynamic modeling method for the indeterminate spindle-bearing system supported by multiple bearings of different types. A spindle-bearing system supported by ball and cylindrical roller bearings is considered. The de Mul’s bearing model is extended for calculating ball and cylindrical roller bearing stiffness matrices with inclusion of centrifugal force and gyroscopic moment. The dependence between spindle shaft reaction forces and bearing stiffness is effectively resolved using an iterative approach. The spindle rotor dynamics is established with the Timoshenko beam theory based finite elements. The spindle reaction forces, bearings stiffness and spindle natural frequencies are obtained with taking into account spindle radial load, ball bearing axial preload and rotational speed effects. The developed method is verified by comparing the simulation results with those from a commercial program.
단거리 이동을 반복하는 위치결정장치를 위한 효율적인 진동저감 방법
홍성욱(Seong-Wook Hong),배규현(Gyu-Hyun Bae) 한국생산제조학회 2013 한국생산제조학회지 Vol.22 No.3
The current vibration reduction methods for positioning systems lead to either complicated motion or the need for additional hardware when the positioning systems carry out frequent short-distance movements. This paper proposes a simple yet efficient vibration reduction method for positioning systems subjected to frequent short-distance movements. The essence of the proposed method is the trapezoidal or triangular velocity profiles, whose acceleration/deceleration rates are designed to be related to the natural frequency of concern. The combined use of the proposed method and the input shaping method is also proposed for the possible application to multimode systems. Experiments are performed to validate the proposed method. The simulation and experiments prove that the proposed method is of great use for residual vibration reduction in positioning systems subjected to frequent short-distance movement.