4. Servo Adjustment
4 - 11
4-3-2 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 "4-2-2 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 be
stabilized.
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. When the vibration cannot be completely eliminated, use another vibration suppression control
(notch filter 3, jitter compensation) in combination with the machine resonance suppression
filter.
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 9000
(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 9000
(Hz)
FEDCBA98765 4 3 2 10
dos hvx svx nfd2 nf3 nfd1 zck
bit Meaning when "0" is set Meaning when "1" is set
1 Set the filter depth for Notch filter 1 (SV038).
2 nfd1 Value 000 001 010 011 100 101 110 111
3
Depth (dB)
Deep
Å
Infntly
deep
-18.1 -12.0 -8.5 -6.0 -4.1 -2.5 -1.2
Shallow
Æ
4 nf3 Notch filter 3 stop Notch filter 3 start (1125Hz)
5 Set the operation frequency of Notch filter 2 (SV046).
6 nfd2 Value 000 001 010 011 100 101 110 111
SV033 SSF2 Servo function
selection 2
7
Depth (dB)
Deep
Å
Infntly
deep
-18.1 -12.0 -8.5 -6.0 -4.1 -2.5 -1.2
Shallow
Æ
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