bnp-b2365(eng)b.pdf - 第226页
4. Servo Adjustment 4 - 27 (5) Setting and adjusting LMC compen sation type 3 LCM comp ensation type 3 can be used to ac commodate quadrant proj ection changes that accompany feed rate and circular radius ch anges which …
4. Servo Adjustment
4 - 26
(4) Adjusting for feed forward control
In LMC compensation, a model position considering the position loop gain is calculated based on
the position command sent from the CNC, and compensation is carried out when the feed changes
to that direction. When the CNC carries out feed forward (fwd) control, overshooting equivalent to
the operation fraction unit occurs in the position commands, and the timing of the model position
direction change may be mistaken. As a result, the LMC compensation timing may deviate, or
compensation may be carried out twice or more.
If feed forward control is carried out and the compensation does not operate correctly, adjust with
the non-sensitive band (SV040 (LMCT)) during feed forward control. In this non-sensitive band
control, the overshooting set with LMCT is ignored during feed forward control. Instead the model
position direction change point is correctly recognized to correctly compensate LMC.
This parameter is meaningless when feed forward control is not being carried out.
<Adjustment method>
If the compensation timing deviates during feed forward control, increase the LMCT setting by 1µm
at a time.
Note that 2µm are set even when the LMCT is set to 0.
No. Abbrev. Parameter name Explanation Setting range
SV040 LMCT
Lost motion
compensation
non-sensitive band
Set the non-sensitive band of the lost motion compensation in the feed
forward control.
When "0" is set, the actual value that is set is 2µm. Adjust by increasing by
1µm at a time.
0 to 100
(µm)
4. Servo Adjustment
4 - 27
(5) Setting and adjusting LMC compensation type 3
LCM compensation type 3 can be used to accommodate quadrant projection changes that
accompany feed rate and circular radius changes which could not be accommodated by LCM
compensation type 2. In this case, on a machine model where the travel direction is reversed, the
viscosity component is also considered in addition to the friction, with compensation occurring in
accordance with the changes in the cutting conditions.
Adjust Compensation parameter (SV016, SV041), a basis of compensation, while measuring
roundness at low speed. Then adjust viscous coefficient (SV086) while measuring roundness at
high speed.
LMC compensation type 3 parameter adjustments should be made while performing a machine
end roundness measurement such as a DDB measurement, etc.
<Adjustment method>
[1] Set the bit1=1 to servo function selection 5 (SV082). (The LMC compensation type 3 will start).
[2] Set a value double the friction torque to the lost motion compensation 1 (SV016). The SV016 setting
value will be used for compensation in the positive and negative directions when the lost motion
compensation 2 (SV041) is 0.
[3] Set the initial value, 1000 to the lost motion compensation viscous coefficient (SV086).
[4] Perform a roundness measurement at such speed as radius R=100mm and feedrate F=1000mm/min
and adjust SV016 value.
[5] Set SV041, when changing the compensation amount in the direction for compensation. The setting
of the compensation direction is shown below with the setting of CW/CCW in the NC parameter. If
compensating only one direction, set –1 to the side not to be compensated.
Compensation
point
CW CCW
A X axis: SV041 X axis: SV016
B Y axis: SV016 Y axis: SV041
C X axis: SV016 X axis: SV041
D Y axis: SV041 Y axis: SV016
[6] Perform a roundness measurement at such speed as radius, R=100mm and feedrate,
F=5000mm/min. (Select a condition to be used for the actual cutting according to the machine's
specification.) Adjust viscous coefficient (SV086) by reducing it gradually to have minimum quadrant
protrusion.
[7] After adjusting SV086, verify its accuracy by performing roundness measurement at low speed again.
POINT
1. As the acceleration of circular feed increases, the quadrant protrusion tends to
get larger. Therefore, the quadrant protrusion gets larger as the circular feedrate
increases for the same radius and as radius gets smaller for the same feedrate.
2. Torque offset (SV032) does not work for LMC compensation type 3.
3. Always set 0 to the lost motion compensation timing (SV039:LMCD).
+Y
-Y
+X
-X
A
The X axis command direction
chan
g
es from + to -.
D
The Y axis command direction
changes from + to -.
B
The Y axis command direction
changes from - to +.
C
The X axis command direction
changes from - to +.
4. Servo Adjustment
4 - 28
No. Abbrev. Parameter name Explanation Setting range
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
bit Meaning when "0" is set Meaning when "1" is set
8 Set the compensation amount with SV016 (LMC1) and SV041 (LMC2).
9
lmc
00: Lost motion compensation stop 10: Lost motion compensation type 2
01: Lost motion compensation type 1 11: Setting prohibited
SV027 SSF1
Servo function
selection 1
SV016 LMC1
Lost motion
compensation 1
Set the compensation amount based on the stall (rated) current of the motor.
The standard setting is double of the friction torque. Setting to "0" means the
compensation amount is zero.
-1 to 200
(Stall [rated]
current %)
SV041 LMC2 Lost motion
compensation 2
Set this with SV016 (LMC1) only when you wish to set the lost motion
compensation amount to be different depending on the command directions.
Set to "0" as a standard.
-1 to 200
(Stall [rated]
current %)
F E D C B A 9 8 7 6 5 4 3 2 1 0
obshj lmc3 lmct
bit Meaning when "0" is set Meaning when "1" is set
1
lmc3
Lost motion compensation 3 stop Lost motion compensation 3 start
SV082
SSF5 Servo function
selection5
SV086 LMCc Lost motion
compensation
viscous coefficient
Set the machine system's viscous coefficient when using lost motion
compensation type 3.
0 to 32767