Mitsubishi MELDAS HS Series Specifications And Instruction Manual page 88

(2) Unbalance torque compensation
If the load torque differs in the positive and negative directions such as with a vertical axis or
slant axis, the torque offset (TOF) is set to carry out accurate lost motion compensation.
<Setting method>
Measure the unbalance torque. Carry out reciprocation operation (approx. F1000) with the axis to
be compensated and measure the load current % when fed at a constant speed on the CNC
servo monitor screen. The unbalance torque at this time is expressed with the following
expression.
Unbalance torque =
The unbalance torque value above is set for the torque offset (TOF).
If there is a difference in the protrusion amount according to the direction, make an adjustment
with LMC2. Do not adjust with TOF.
(Example)
Assume that the load current % was −40% in the + direction and −20% in the –
direction when JOG feed was carried out at approx. F1000. The unbalance torque is
as shown below, so −30% is set for TOF.
No. Abbrev. Parameter name
SV032 TOF Torque offset
POINT
(3) Adjusting the lost motion compensation timing
If the speed loop gain has been lowered from the standard setting value because the machine
rigidity is low or because machine resonance occurs easily, or when cutting at high speeds, the
quadrant protrusion may appear later than the quadrant changeover point on the servo control. In
this case, suppress the quadrant protrusion by setting the lost motion compensation timing
(SV039: LMCD) to delay the LMC compensation.
<Adjustment method>
If a delay occurs in the quadrant protrusion in the circle or arc cutting as shown below in respect
to the cutting direction when CNC sampling measurement (DDB measurement) or actual cutting
is carried out, and the compensation appears before the protrusion position, set the lost motion
compensation timing (SV039:LMCD).
While measuring the arc path, increase LMCD by 10 msec at a time, to find the timing that the
protrusion and compensation position match.
Before timing delay compensation
Chapter 8 Adjustment
(+ feed load current %) – (– feed load current %)
−40 + (−20)
= − 30%
2
Unit
Set this when carrying out lost motion compensation.
Stall % (rated
current %) Set the unbalance torque amount.
Even when TOF is set, the torque output characteristics of the motor and load
current display of the CNC servo monitor will not change. Both the LMC
compensation and collision detection function are affected.
Cutting
direction
2
Explanation
After
compensation
After timing delay compensation
8–21
Setting range
–100 to 100