Vibration Diagnosis

  • View
    125

  • Download
    9

Embed Size (px)

Transcript

Khun Sommai TongphasookPage 126/Sep/03 Vibration Diagnosis Mass Unbalance A) Force Unbalance First Rotor Critical ( 3 9 ) 1X RPM . . OB & IB 0,, Bearing 90 (30) B) Couple Unbalance 180 . 1X RPM . First Rotor Critical Speed. . 2 . OB & IB 180. , Bearing 90 (30) . Khun Sommai TongphasookPage 226/Sep/03 C) Dynamic Unbalance Force Couple Unbalance. 1X RPM 2 OB & IB 0 180o. , OB & IB ( 30 o)., 90 o ( 40 o) D) Overhung Rotor Unbalance 1X RPM . . , ( 30 o). Overhung Rotor Force Couple Unbalance, . 2 Force Unbalance. Khun Sommai TongphasookPage 326/Sep/03 Eccentric Rotor Pulley, Gear, Bearing, Motor armature . 1X RPM . 0o 180 o (). ( ) Bent Shaft 180 o 1X , 2X ( .) Dial Indicator Misalignment A) Angular Misalignment, 180o . 1X 2X RPM. , 1X, 2X 3X. . Harmonics 1X RPM . Mechanical loosness C, Harmonics Noise Floor Spectrum. Khun Sommai TongphasookPage 426/Sep/03 B) Offset Misalignment , 180o . 2X 1X . , Harmonic (4X 8X), Harmonic Mechanical Looseness. Spectrum . Noise Floor . C) Misalign Bearing Cocked on Shaft. Bearing (CockedBearing) . 180 o / Bearing . . Bearing . Mechanical Looseness VibrationSpectrum A , B C Khun Sommai TongphasookPage 526/Sep/03 A. / Feet, Baseplate Foundation ; Grouting, Hold Down Bolts ; ( Soft foot) 90 o- 180 o Bolt, Machine Foot, Base Plate Base B. Bolt Pillowblock, Bearing C. Harmonics Nonlinear Response. (Truncation) Time Wave Form Noise Floor Spectrum. Bearing , Bearing , Sleeve Rolling Elemant Bearing, Impeller . , Start . (Highly directional) Khun Sommai TongphasookPage 626/Sep/03 30 o Bearing Housing. Subharmonic 1/2 1/3 X RPM (0.5X, 1.5X, 2.5X,) 4. Rolling Element Bearing Failure Stages. Stage 1: Ultrasonic Frequency 250 350 KHz;, , 20 60 KHz (1,200 - 3,600 kCPM) SpikeBnergy (gSE), HFD(g) ShockPulse (dB). Spike Energy 0.25 gSE 1 ( ). Enveloped Spectra 1 . Stage 2: (fn) 30 120 K CPM. Resonance . (Sideband Frequeneics) 2 . Overall Spike energy (, 0.25 0.5 gSE) Khun Sommai TongphasookPage 726/Sep/03 Stage 3: Bearing . , Side Bands , Bearing Bearing . Overall Spike Energy (, 0.5 1 gSE). Bearing, Side bands Bearing . High Frequency Demodulated (HFD) Enveloped Spectra 3. Bearing ! ( Bearing Sprectrum) Stage 4:, 1X RPM . , Harmonics. Bearing Bearing Nosie Floor High Frequemey Noise Floor Spike Energy ;, Spike Energy HFD Khun Sommai TongphasookPage 826/Sep/03 Resonance , , , . (Support Frame), (Foundation), (Gear box) (Drive belts). , ( 90 , 180 ). . ( Plain Bearing (Over hung) Rotor Rub Spectrum . . , . Subharmonics (1/2 , 1/3 , , 1/5 , -----1/n), . ( ). (Bearing Babbit). Khun Sommai TongphasookPage 926/Sep/03 (.) Journal Bearing A) Wear / Clearance Problems Harmonics( 10 20 ). , 1X RPM. / Bearing . B) Oil Whirl Instability 0.40 0.48 X RPM . 40 % Eearing Clearance. ( ) Bearing. ( ). . . , Khun Sommai TongphasookPage 1026/Sep/03 B) Oil Whip Instability 2 . 2 , . . . . C) Hydraulic and Aerodynamic Forces A) Blade Pass & Vane Pass (BPF) = X RPM. Pump, Fans Compressor, . BPF ( Harmonics) Pump Vanes Diffusers. BPF ( Harmonics) . BPF Impeller Wear Ring diffuser Vanes .BPF , , Damper Pump Fan Housing . Khun Sommai TongphasookPage 1126/Sep/03 B) Flow Turbulence . , 50 2,000 CPM. Compressor, . . C) Cavitation Cavitation , Harmonics BPF. (Starvation). Cavitation Pump . (Erode) . Cavitation, Pump. Cavitation . , ( ) Gears A) Normal Spectrum Gears & Pinion (GMF) GMF Harmonics. GMF Harmonics Sidebands . Peak Gear . Fmax 3.25 X GMF ( ) . , Fmax 200X RPM . Khun Sommai TongphasookPage 1226/Sep/03 B) Tooth Wear Sidebands . Sidebands . GMF . Sidebands GMF. 2X GMF 3X GMF ( 3X GMF) GMF . C) Tooth Load Gear Mesh Load. GMF , Sideband Gear . . D) Gear Eccentricity and Backlash. Sidebands GMF Harmomies Gear Eccentricity, Backlash Non- Parallel Shafts Gear Modulate GMF . Gear Sideband. 1X RPM Eccentric, Gear Gear . Backlash GMF Harmonics Gear, Sideband 1X RPM. GMF Load Back lash . Khun Sommai TongphasookPage 1326/Sep/03 E) GearMisalignment Harmonics 2X GMF Sideband . 1X GMF, 2X 3X GMF. Fmax 3 GMF Harmonics. Sideband 2X GMF 2X RPM . Sideband GMF GMF Harmonics . . F) Cracked / Broken Tooth Gear 1X RPM Gear Time Waveform , Sideband 1X RPM. Time Waveform (Spike) . ( ) 1/RPM Gear. Impact Spike Time Waveform 1X RPM FFT 10 20 ! Khun Sommai TongphasookPage 1426/Sep/03 G) GearAssemblyPhaseProblems; GearAssemblyPhase Freq.(GAPF)GMF/NA( NA > 1).TG/ NA GearTP/ NAPinion NA , ... Gear Pinion(NA = AssemblyPhaseFactor).GAPF (Harmonics) . (Spectrum) , Gear H) HuntingToothProblems.HuntingTooth (FHT) GearPinion,. 600 cpm , .Gear . FaultyPinionFaultyGear. ( , 10 20, FHT) TGEARTPINIONGearPinion.NA AssemblyPhaseFactor ModulateGMFGearRPM. Khun Sommai TongphasookPage 1526/Sep/03 I) LooseBearingFit.BearigGears Harmonics, GMF,2GMF/3GMF.GMF Bearing.Bearing Bearing Journal., Gear AC.InductionMotors A)StatorEccentricity, ShortedLaminationsOrLooseIron.Stator 2X(2FL). StatorRotor stator . 5%10% (Synchronus).SoftFoot (WarpBases) Stator. (LooseIron)Stator. StatorLaminations . (Thermally inducedvibration) StatorDistortionStaticairgap. Khun Sommai TongphasookPage 1626/Sep/03 B) EccentricRotor (VariableAirGap.) Rotor RotorStator ( 2FL HarmonicRunningSpeed ). Spectrum 2FL Harmonic RunningSpeed.RunningSpeed 2FLPolePassFrequency(FP) FP RunningSpeed.FP (PolePassFrequency = SlipFrequency X # Poles). FP 20 120CPM, (0.3 2.0 Hz). SoftFoot. (Misalignment) (; ) C) RotorProblems RotorBarShortingRing;RotorBarShortingRing; RotorLamination 1XRunningSpeedPolePassFrequency (Fp). FP HarmonicsRunningSpeed2X,3X,4X5X.Rotorbar2 FL RotorBarPassFrequency (RBPF)/Harmonic (RBPF = BarX RPM).2XRBPF, 1XRBPF Arc RotorBarsEndRings 2XRBPF( 2 FL ); 1XRBPF. Khun Sommai TongphasookPage 1726/Sep/03 D) PhasingProblemConmectorsVibration 2 (2FL) Sidebands 1/3 (1/3 FL) FL 2 FL 1.0 in/sec .Connector . Connectors . ACSynchronous Motors LooseStatorCoilsSynchronousMotor VibrationCoilPassFrequency (CPF) StatorCoils X RPM (#StatorCoils = #Poles X #Coils/Pole).CoilPassFrequencysidebands1X RPM.SynchromousMotorAmplitude 60,000 90,000CPM, Sidebands 2 FL . Spectrum 90,000 CPMBearingMotor. DC Motors And Controls Khun Sommai TongphasookPage 1826/Sep/03 A) NormalSpectrumDCMotorVibration.Full waveRectified(6 SCRS) 6 (6 FL = 360 HZ = 21,600 CPM);Half waveRectified(3 SCRS) 3 . (3FL = 10,800 HZCPM). SCRFiringFrequencySpectrumDCMotor, Amplitude. Peaks FL B)Broken Armature Windings, Grounding Problems or Faulty System Tuning DCMotorSCR2XSCR,BrokenMotorWinding . SCR 2X SCR . 0.1 in/scepeak 1XSCR0.4in/sce 2XSCRFiringFrequency. C)FaultyfiringCardorBlownFuseFiringCard 1/3 , 1/32/3X SCR (1/3 X SCRFreq. = 1 X FL DCmotor Halt WaveRectified, 2XFL DCMotor Full WaveRectifiedSCR) :Card / SCR Motor.(#SCR s, #FiringCards, etc.) Khun Sommai TongphasookPage 1926/Sep/03 C)Faulty SCR, Shorted Control Card, Loose Connectionsand/orBlownfuse.Vibration (FL)SCRFiring. , SCR 1 FL/5 FL 6 SCR. FL, 2FL, 4FL, 5FL Spectrum DC Motor D)FaultyComparitorCard.Hunting. .Sidebands FFT.Sidebands . F)ElectricalCurrentPassThruDCMotorBearing.Fluting BearingOuterraces(BPFO) , FlutingOuter Innerraces. 100,000 150,000CPM. SpectrumFmax 180 K CPM1600 OutBoardInboardBearingDCMotor Khun Sommai TongphasookPage 2026/Sep/03 BeltDriveProblems. BeltFreq.=3.142xPulleyRPMxPitchDiam BeltLength TimingBeltFreq.=BeltFreq. x # BeltTeeth =PulleyRPMx#PulleyTeeth. A) Worn, Loose or Mismatch Belts.MotorDrivenMachine.,, 34.2., . TimingBelt, PulleyTimingBelt. ChainPass FrequencySprocketxRPM. B) Belt/Pulley Misalignment1X RPM. . MassFrameStiffness.Pulley, MotorFan .PhasePhasefilterPulleyPhase Rotor . Khun Sommai TongphasookPage 2126/Sep/03 C) EccentricPulleys1XRPMPulley. Bearing. BalancePulley WasherTaper-lockBolts. ,Balance, (FatigueStress).Pulley (PhaseAnalysis) 0 180 D) BeltResonance, Motor. , .BeltResonance PulleysBearing., , . Khun Sommai TongphasookPage 2226/Sep/03 Beatvibration, BeatFrequency2 . (WidebandSpectrum) . 2 . 2 (F2 F1) BeatFrequency.BeatFrequency , 5 100CPM. TimeWaveform (F1) TimeWaveform (F2).Waveforms180