bnp-b2365(eng)b.pdf - 第213页

4. Servo Adjustment 4 - 14 (4) Variable speed loop gain control If vibration occurs when the motor is rotating at a high speed, su ch during rapid traverse, or if disturbing noise occurs, the state can be improv ed by lo…

4. Servo Adjustment

4 - 13

(2) Jitter compensation (Vibration control when motor is stopped.)

The load inertia becomes much smaller than usual if the motor position enters the machine

backlash when the motor is stopped. Because this means that an extremely large VGN1 is set for

the load inertia, vibration may occur.

Jitter compensation can suppress the vibration that occurs at the motor stop by ignoring the

backlash amount of speed feedback pulses when the speed feedback polarity changes.

Increase the number of ignored pulses by one pulse at a time, and set a value at which the

vibration can be suppressed. (Because the position feedback is controlled normally, there is no

worry of positional deviation.)

When jitter compensation is set to an axis that is not vibrating is set, vibration could be induced, so

take care.

(3) Adaptive filter

The servo drive unit detects the machine resonance point and automatically sets the filter constant.

Even if the ball screw and table position relation changes causing the resonance point to change,

the filter will track these changes. If the sensitivity to detect the vibration is insufficient and the

effect of the filter is not apparent, increase the sensitivity (SV027/bitC, D). The filter coefficient is

recalculated when the power is turned ON again, so vibration may occur temporarily.

Notch filter 4 and notch filter 5 cannot be used together.

No. Abbrev. Parameter name Explanation

SV027 SSF1

Servo function

selection 1

F E D C B A 9 8 7 6 5 4 3 2 1 0

aflt zrn2 afse ovs lmc omr zrn3 vfct upc vcnt

<Jitter compensation> Removal of vibration when motor is stopped

bit Explanation

4 Set the number of compensation pulses of the jitter compensation.

vfct

00: Jitter compensation invalid 10: Jitter compensation 2 pulses

01: Jitter compensation 1 pulse 11: Jitter compensation 3 pulses

bit Meaning when "0" is set Meaning when "1" is set

C 00: Adaptive filter sensitivity standard

afse

11: Adaptive filter sensitivity increase (Set 2bits at a time)

E zrn2 Set to "1".

F aflt Adaptive filter stop Adaptive filter start

POINT

Jitter compensation vibration suppression is only effective when the motor is

stopped.

4. Servo Adjustment

4 - 14

(4) Variable speed loop gain control

If vibration occurs when the motor is rotating at a high speed, such during rapid traverse, or if

disturbing noise occurs, the state can be improved by lowering the speed loop gain during

high-speed rotation. The low-speed region speed loop gain used for cutting feed (G1 feed), etc., is

maintained at a high level, so the vibration can be improved without dropping the machining

accuracy.

No. Abbrev. Parameter name Explanation Setting range

SV005 VGN1 Speed loop gain 1 Set the speed loop gain.

Set this according to the load inertia size.

The higher the setting value is, the more accurate the control will be,

however, vibration tends to occur.

If vibration occurs, adjust by lowering by 20 to 30%.

The value should be determined to be 70 to 80% of the value at the

time when the vibration stops.

1 to 999

VGN1

VGN2

VCS VLMT

SV006 VGN2 Speed loop gain 2 If the noise is bothersome at high

speed during rapid traverse, etc, lower

the speed loop gain.

As in the right figure, set the speed

loop gain of the speed 1.2 times as

fast as the motor’s rated speed, and

use this with SV029 (VCS).

When not using, set to "0".

(Rated speed × 1.2)

-1000 to 1000

SV029 VCS Speed at the change

of speed loop gain

If the noise is bothersome at high speed during rapid traverse, etc,

lower the speed loop gain.

Set the speed at which the speed loop gain changes, and use this with

SV006 (VGN2). (Refer to SV006.)

When not using, set to "0".

0 to 9999

(r/min)

4. Servo Adjustment

4 - 15

4-3-3 Improving the cutting surface precision

If the cutting surface precision or roundness is poor,

these can be improved by increasing the speed

loop gain (VGN1, VIA) or by using the disturbance

observer function.

• The surface precision in the 45° direction of a

taper or arc is poor.

• The load fluctuation during cutting is large,

causing vibration or surface precision defects

to occur.

POINT

Adjust by raising the speed loop gain equivalently to improve cutting surface

precision, even if the measures differ. In this case, it is important how much the

machine resonance can be controlled, so adjust making sufficient use of

vibration suppression functions.

(1) Adjusting the speed loop gain (VGN1)

If the speed loop gain is increased, the cutting surface precision will be improved but the machine

will resonate easily.

The final VGN1 setting should be approx. 70 to 80% of the maximum value where resonance does

not occur. (Refer to "4-2-2 (1) Setting the speed loop gain")

(2) Adjusting the speed loop leading compensa tion (VIA)

The VIA has a large influence on the position trackability, particularly during high-speed cutting

(generally F1000 or more). Raising the setting value improves the position trackability, and the

contour precision during high-speed cutting can be improved. For high-speed high-precision

cutting machines, adjust so that a value equal to or higher than the standard value can be set.

When VIA is set lower than the standard value and set to a value differing between interpolation

axes, the roundness may worsen (the circle may distort). This is due to differences occurring in the

position trackability between interpolation axes. The distortion can be improved by matching the

VIA with the smaller of the values. Note that because the position trackability is not improved, the

surface precision will not be improved.

(Refer to "4-2-2 (2) Setting the speed loop leading compensation")

No. Abbrev. Parameter name Explanation Setting range

SV005 VGN1 Speed loop gain 1

Set the speed loop gain.

Set this according to the load inertia size.

The higher the setting value is, the more accurate the control will be,

however, vibration tends to occur.

If vibration occurs, adjust by lowering by 20 to 30%.

The value should be determined to be 70 to 80% of the value at the time

when the vibration stops.

1 to 999

SV008 VIA Speed loop lead

compensation

Set the gain of the speed loop integration control.

The standard setting is "1364". During the SHG control, the standard

setting is "1900". Adjust the value by increasing/decreasing it by about

100 at a time.

Raise this value to improve contour tracking precision in high-speed

cutting. Lower this value when the position droop vibrates (10 to

20Hz).

1 to 9999