Chapter 5 Adjustment
5-11
5-3-2 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 "5-2-2 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.
No. Abbrev. Parameter name Explanation Setting range
SV005 VGN1 Speed loop gain
Set according to the load inertia size.
If machine resonance occurs, adjust by lowering the value by 20 to 30%
at a time. The final setting value should be 70 to 80% of the maximum
value where resonance does not occur.
1 ~ 999
POINT
Suppress the vibration using the vibration suppression functions, and maintain
the speed loop gain (SV005: VGN1) as high as possible.
(1) Notch filter 1
The resonance elimination filter will function at the set frequency. Use the D/A output function to
output the current feedback and measure the resonance frequency. Note that the resonance
frequency that can be measured is 0 to 500 Hz. For resonance exceeding 500 Hz, directly
measure the phase current with a current probe, etc.
When the notch filter is set, vibration may occur at a separate resonance frequency that existed
latently at first. In this case, the servo control is stabilized when the notch filter depth is adjusted
and the filter is adjusted so as not to operate more than required.
<Setting method>
1. Set the resonance frequency in the notch filter frequency 1 (SV038: FHz1).
2. If the machine starts to vibrate at another frequency, raise (make shallower) the notch 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 (jitter compensation, adaptive filter) in combination with the notch filter.
No. Abbrev. Parameter name Explanation Setting range
SV038 FHz1 Notch filter frequency 1
Set the resonance frequency to be suppressed. (Valid at 72 or
more).
Set 0 when the filter is not to be used.
0 ~ 3000
SV033 SSF2 Servo function selection 2 The notch filter 1 depth compensation is set with the following parameters.
F E D C B A 9 8 7 6 5 4 3 2 1 0
afs fhz2 nfd
bit Descriptions
0~3 nfd
Set the filter depth for the notch filter.
Deeper ← → Shallower
Setting value 0 2 4 6 8 A C E
Depth (dB) ∞ −18.1 −12.0 −8.5 −6.0 −4.1 −2.5 −1.2
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