Mitsubishi Electric HG-AK, Instruction Manual

Page: 366 / 392

APPENDIX
App. - 19
(4) Continuous effective load torque
If the torque required for the servo motor changes with time, the continuous effective load torque should
be lower than the rated torque of the servo motor. There may be a servo motor torque delay at the start
of acceleration or deceleration due to a delay in the control system. To simplify the calculation, however,
it is assumed that constant acceleration and deceleration torques are applied during t
psa
and t
psd
.
The following equation is used to calculate the continuous effective load torque in the following operation
pattern. T
LH
indicates the torque applied during a servo motor stop. A large torque may be applied
especially during a stop in vertical motion applications, and this must be fully taken into consideration.
During vertical drive, the unbalanced torque T
U
will become T
LH
.
0
Servo motor speed N [r/min]
t
psd
Time
Time
T
L
T
a
T
d
T
Md
t
psa
t
c
t
f
(1 cycle)
tl
0
T
Ma
T
LH
Serv
o motor torque
T
rms
=
t
f
T
Ma
2
• t
psa
+ T
L
2
• t
c
+ T
Md
2
• t
psd
+ T
LH
2
• tl
································································· (5.14)