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9. Adjustment
9 - 12
9-3-2 Vibration suppression measures
If vibration (machine resonance) occurs, it can be suppressed by lowering the speed loop gain (VGN1).
However, cutting precision and cycle time will be sacrificed. (Refer to "9-2-2 Speed loop gain".) Thus, try
to maintain the VGN1 as high as possible, and suppress the vibration using the vibration suppression
functions.
If the VGN1 is lowered and adjusted because vibration cannot be sufficiently suppressed with the
vibration suppression functions, adjust the entire gain (including the position loop gain) again.
<Examples of vibration occurrence>
• A fine vibration is felt when the machine is touched, or a groaning sound is heard.
• Vibration or noise occurs during rapid traverse.
POINT
Suppress the vibration using the vibration suppression functions, and maintain
the speed loop gain (SV005 (VGN1)) as high as possible.
(1) Notch filter
The notch filter operates at the set frequency. Measure the resonance frequency with the current
feedback analog output function, and set that frequency in SV038 or SV046.
If the notch filter is set to a particularly low frequency, vibration may occur initially due to another
resonance frequency that existed latently. If the notch filter's depth compensation (SV033 (nfd1,
nfd2)) is adjusted so that the filter does not operate unless necessary, the servo control will
stabilize.
Notch filter 3 (SV033 (bit4)) is a filter with frequency fixed to 1125Hz, and has no depth compensation.
<Setting method>
1. Set the resonance frequency in the machine resonance suppression filter frequency (SV038
(FHz1), SV046 (FHz2)).
2. If the machine starts to vibrate at another frequency, raise (make shallower) the machine
resonance suppression filter depth compensation value (SV033 (SSF2.nfd)), and adjust to the
optimum value at which the resonance can be eliminated.
3. If the vibration cannot be removed completely, use another vibration suppression control (notch
filter 3, jitter compensation).
No. Abbrev. Parameter name Explanation Setting range
SV038 FHz1 Notch filter frequency
1
Set the vibration frequency to suppress if machine vibration occurs.
(Valid at 36 or more) When not using, set to "0".
0 to 4500
(Hz)
SV046 FHz2 Notch filter frequency
2
Set the vibration frequency to suppress if machine vibration occurs.
(Valid at 36 or more) When not using, set to "0".
0 to 4500
(Hz)
SV033 SSF2 Servo function
selection 2
F E D C B A 9 8 7 6 5 4 3 2 1 0
zup dis nfd2 nf3 nfd1
bit
Meaning when "0" is set Meaning when "1" is set
1 Set the filter depth for Notch filter 1 (SV038).
2 nfd1
Value
Deep
000 001 010 011 100 101 110 111 Shallow
3 Depth (dB) -
∞
-18.1 -12.0 -8.5 -6.0 -4.1 -2.5 -1.2
4 nf3 Notch filter 3 stop Notch filter 3 start (1125Hz)
5 Set the operation frequency of Notch filter 2 (SV046).
6 nfd2
Value
Deep
000 001 010 011 100 101 110 111 Shallow
7 Depth (dB) -
∞
-18.1 -12.0 -8.5 -6.0 -4.1 -2.5 -1.2