06 diagnóstico de máquinas
DESCRIPTION
vibraciones: diagnostico de maquinasTRANSCRIPT
UNIDAD II
ANALISIS VIBRACIONAL
APLICACIONES EN MÁQUINAS
Espectro de Máquina
v [mm/s]
fn f
(Hz)
1. DESBALANCE
Fundamental Frecuency fn =Evaluation criteria:ISO 10816-3 ISO 1940
n (rev/min) 60
n
2. DESALINEAMIENTO
Machine spectrum:
v [mm/s]
Fn 2xFn f (Hz)
Axial :mainly Angular
Misalignment
radial :Mainly Offset
fz 2xfz 3xfz 4xfz f en Hz
Espectroa enmm/s²
fn2
z1
z2
fn1
Harmonics of fz visibleSide bands with fn
Frecuencia en Mecanismos de Engrane fz =fn1*z1
fz =fn2*z2
z1, z2: número de dientesfn1: Frecuencia Rotacional de la Rueda Conductora
3.Fallas de Frecuencia de Engrane
Side bands with fn
Side band distance fn is the
fundamental frequency of the defective gear (broken tooth)
Many side bands around fz,
gear mesh with slowly decreased amplitudes
z2
fn1
fn2
z1
Fz 2xfz 3xfz f en Hz
Espectro:a enmm/s²
4. Fisura/Rotura de Engranaje
5.Cimentación Mala
fn
fn 2xfn 3xfn 4xfn usw. f en Hz
Espectro de Maquina:v enmm/s
Harmonics of fn are visible
- fundamental freq. fn =
-Root Cause: Resonance or Instability
RPM[Rev/min] 60
s = 9
Espectro de Máquina
x=3(eg. fixture for bearing)
fn
Fn fBPF x fBPF f en Hz
v enmm/s
6.Turbulencia
Blade pass frequency fBPF high
amplitude
- blade pass frequency: fBPXF = fn s
- higher orders xfBPF = fn s x
- s:number of blades
- x:number of disturbance locations
fn
v enmm/s
a) Espectro de Máquina
fn 2xfn 3xfn 4xfn 5xfn f en Hz
7. Resonancia
Resonance step-up
Phase shift of 180°
b) Bode diagram
v enmm/s
nRes n
en °
nRes n
c) Diagrama de Cascada para diferentes RPM
Resonance step-up
v en mm/s
n en Rev/min
Frecuencia Natural f en Hz
fn 2xfn 3xfn
fn
8. Rotor en Rozamiento
v enmm/s
fn 2xfn 3xfn etc. f en Hz
Espectro de Máquina
many Harmonics of fn up to high orders
(10 times ... 20 times)
a enm/s²
t en ms
T
1 Revolución
Acceleration Time Signal
1 shock pulse per Revolution in the time domain of the acceleration signal
Period length T =
1 fn
Campo Magnético Asimétrico en el Estator (Motor Eléctrico)
fn
fNetz
fn 2xfL f en Hz (49,85 Hz) (100 Hz)
v enmm/s
Espectro de Máquina
2-times fL visible
-Line frequency fL = 50,0 Hz
- Exception: Frequency converter Drives
Shorted LaminationsRotor eccentricityasymmetric power feedasymmetric winding
v enmm/s
99,0 2xfn 2xfL 101,0 f en Hz (100 Hz)
Zoom Espectro de Máquina:
No side bands around 2xfL
2-pole machines:
2-times fundamental freq. fn
slightly below 2 fL !
fn 2xfL f en Hz (49,85 Hz) (100 Hz)
v enmm/s
Espectro de Máquina
2-times fL visible
-Line frequency fL = 50,0 Hz
- Exception: Frequency converter Drives
fline
nbar
fn
Armature field fault (Rotor Electric machines):
Bar breakage Bar fracture Bar looseness
Bar passing frequencies fBar with side
bands visible at 2 fL intervals
Bar passing frequency fBar = fn nBar
With: nBar = number of armature bars
fL = 50,0 Hz - Line frequency
fn = fundamental frequency
fn 2xfLfBar f en Hz
v enmm/s Espectro de Máquina
99,0 2xfL 101,0 f en Hz (100 Hz)
v enmm/s
Espectro de Máquina
Armature field fault (Rotor Electric machines):
Sidebands visible around 2 fL at
fslip intervals
with slip frequency fslip = - fn
with p = number of stator poles
2 fL
p
Machine vibrationdisplacementvelocity
R.bearing condition:Shock pulse valuedBm-value,dBc-valueacceleration
Cavitation:Shock pulse value dBcav-valueacceleration
Measurement locations - vibration measurement