• Title/Summary/Keyword: Rotor Unbalance

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An Efficient Method for the Mass Unbalance Analysis of a Rotor System Using FFT and Lissajous Diagram

  • Su, Hua;Chong, Kil-To
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.1612-1617
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    • 2004
  • Unbalance analysis is essential in the rotor system. However, some problems still remain in the aspects of computational efficiency and accuracy. In the present paper a new method is proposed for estimating the mass unbalance of a rotating shaft by using the vibration signals. This is an advanced new method for the detection of a mass unbalance and its phase position. Based on the signal processing with FFT, an estimator is designed to detect the mass of unbalance. And an improved Lissajous diagram is also introduced with statistical analysis, which make it possible to compute the phase position of the mass unbalance efficiently and arranged at a certain location of the shaft. The proposed method is demonstrated and validated through several test examples.

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Dynamic Behavior Analysis of Rotor-Bearing System Under External Forces in Swash Plate Compressor (외부 가진력을 고려한 사판식 압축기 회전축-베어링계의 동적 거동 해석)

  • 김태종
    • Tribology and Lubricants
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    • v.17 no.1
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    • pp.56-63
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    • 2001
  • The dynamic behavior of rotor-bearing system used in swash plate compressor has been investigated using the combined methodologies of finite elements and transfer matrices. The finite element is formulated including the field element for a shaft section and the point element for swash plate, disk pulley and bearings. The Houbolt method is used to consider the time march for the integration of the system equations. The transient whirl response of rotating shaft supported on roller bearings is obtained, considering compression forces and unbalance forces at swash plate and driving pulley. And, the steady state displacements of the rotor are compared with a variation in unbalance mass. Results show that the loci of rotating shaft considering unbalance forces and external compression forces are more severe in flutter motion than with only unbalance forces.

Unbalance Response Analysis of Induction Motor Rotor Considering Unbalanced Electromagnetic Forces (불평형 전자기력을 고려한 유도전동기 회전자의 불평형 응답해석)

  • 손병구
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.2
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    • pp.201-209
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    • 1999
  • This paper presents a general analytical method for analyzing mechanical unbalance response of unbalanced electromagnetic forces produced in induction motors with an eccentric rotor and a phase unbalance. The equations to be solved are a set of second order differential equations which give matrices with periodic coefficients that are a function of time due to the unbalanced electro-magnetic force. Unbalance response is processed by Newmark $\beta$ method. Two examples are given including an industrial application. The results show that the method proposed is satisfactory.

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Effects of Hydraulic Force on the Unbalance Vibration of Centrifugal Pump Rotors (원심펌프 회전축계의 불평형 응답에 미치는 유체력의 영향)

  • 양보석;최원호
    • Tribology and Lubricants
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    • v.2 no.2
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    • pp.20-26
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    • 1986
  • The paper presents an analytical investigation of the unbalance vibrations of a pump rotor. The analysis applies to rotor-bearing-seal-impeller systems which consist of rigid disks, distributed parameter rotor elements and discreate bearings, seals, and impellers. The dynamic hydraulic force of bearing, seal and impeller elements are represented by four stiffness coefficients arid four damping coefficients. Numerical results are presented for unbalance response associated with various kinds bearing, and with effects of seal and impeller forces.

A Study on Dynamic Characteristics of Synchronously Controlled Hydrodynamic Journal Bearing (동기 제어되는 동압 베어링의 동특성에 관한 연구)

  • Rho, Byoung-Hoo;Kim, Kyung-Woong
    • Proceedings of the KSME Conference
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    • 2001.06c
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    • pp.311-315
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    • 2001
  • In this paper synchronous whirl of bearing is employed as control algorithm of actively controlled hydrodynamic journal bearing to suppress the whirl instability and unbalance response of a rotor-bearing system. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than conventional analysis which uses the Reynolds condition. The stability and unbalance responses of a rotor-bearing system are investigated for various control gain and phase difference between the bearing and journal motion. It is shown that the unbalance response of a rotor-bearing system can be greatly improved by synchronous whirl of the bearing, and there is an optimum phase difference, which gives the minimum unbalance response of the system, at given operating condition. It is also found that the speed at onset of instability can be greatly increased by synchronous whirl of the bearing.

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Unbalance Response Analysis of Copper Die Casting High Speed Induction Motor (동 다이캐스팅 고속 유도전동기의 불평형 응답 해석)

  • Hong, Do-Kwan;Jung, Seung-Wook;Woo, Byung-Chul;Koo, Dae-Hyun;Ahn, Chan-Woo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.7
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    • pp.642-649
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    • 2012
  • This paper deals with a copper die casting induction motor which has several advantages of motor performance. The developed motor is used as spindle motor in machining center. The dynamic characteristic analysis of rotor is dealt with for precision machining. The critical speed of rotor considering rotation and gyroscopic effect should be above operating speed, 18,000 rpm, and have a 201 % sufficient separation margin. Also, the 3-D unbalance vibration response analysis is performed and enabled the prediction of the expected vibration amplitude by unbalance in high speed. The unbalance vibration responses of each position on the rotor are satisfied with allowable vibration displacement of API 611 standard according to balancing G grade(G 0.4, G 2.5, G 6.3). Copper die casting high speed induction motor is successfully developed and verified by experiment.

Isotropic Control of Rotor Bearing System (회전체 베어링계의 등방 제어)

  • 김철순;이종원
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1993.04a
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    • pp.101-106
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    • 1993
  • A new rotor control scheme, the isotropic control of anisotropic rotor bearing system in complex state space, is proposed, which utilizes the concepts on the eigenstructure of the isotropic rotor system. Then the control scheme is applied to an active magnetic bearing system and the control performance is investigated in relation to control energy, transient response, and unbalance response. In particular, it is shown that the proposed method is efficient for control of unbalance response.

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On-line Balancing of a Ultra-high speed Rotor with Residual Unbalance (자기베어링을 이용한 잔류질량불균형이 존재하는 초고속 회전체의 온라인 밸런싱)

  • 송상호
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.7 no.1
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    • pp.51-57
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    • 1998
  • In order to minimize vibration problems of rotating machinery rotors have been assembled through balancing machines. Since perfect balancing is impossible, residual unbalances cause serious vibration while the rotor is in high speed region. To minimize unbalance effects of magnetic bearing systems (AMB) during rotation on-line balancing methodology was studied. Unbalances were considered as disturbances of the system. The disturbance observer was used to estimate unbalance force from measurable state and input variables. Balancing inputs computed according to LQR and outputs of the observer were applied to eliminate unbalances during high speed rotation of the AMB. the effectiveness of the on-line balancing was verified through numerical simulations.

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A study on balancing performance of self-compensating liquid balancer (자기보상형 액체 평형장치의 평형잡이 성능에 관한 연구)

  • 양보석;이재무;김원철;고장권
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.1
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    • pp.35-41
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    • 1998
  • A Self-compensating liquid balancer is proposed, which consists of the vessel contains liquid available to compensate for rotor unbalance, and the vessel provides four sets of suction pipe and reservior. Under the centrifugal field the liquid moves through the pipe from the side of the unbalance mass to the reservior located on the symmetrically opposite side. The liquid balancer was confirmed experimentally to be useful for the balancing of rotor over the critical speed, and the whirling amplitude after balancing decreases to almost constant value in spite of the location and size of unbalance.

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A Coupled Unbalance Response Analysis of Geared Two-Shaft Rotor-Bearing System (2축 로터-베어링 시스템의 연성 불균형 응답해석)

  • 이안성;하진웅
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.220-226
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    • 2002
  • A general solution method is presented to obtain the unbalance response orbit from the finite element based equations of motion of a gear-coupled two-shaft rotor-bearing system. Particularly, are proposed the analytical solutions of major and minor axis radii of the orbit. The method has been applied to analyze the unbalance response of a 800 refrigeration-ton turbo-chiller rotor-bearing system, having a bull-pinion speed increasing gear. The bumps of unbalance responses have been observed at the first torsional natural frequency due to the coupling of lateral and torsional dynamics by the gear meshing. Further, the proposed analytical solutions have been validated with results obtained by a full numerical approach.

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