Mitsubishi MELDAS MDS-C1

5. Spindle Adjustment
5 - 16
5-3-2 Adjusting the acceleration/deceleration operation
(1) Calculating the theoretical acceleration/deceleration time
The theoretical acceleration/deceleration time is calculated
for each output range based on the spindle motor output
characteristics as shown on the right. Note that the load
torque (mainly frictional torque) is assumed to be 0 in this
theoretical expression, so the time tends to be shorter than
the acceleration time with the actual machine.
1) Maximum motor output during
acceleration/deceleration: Po
During acceleration/deceleration, the motor can output at
120% of the short-time rating. Thus, the motor output Po
in the output range during acceleration/deceleration
follows the expression below.
Po = (Short-time rated output) × 1.2 [W]
2) Total load GD
2
: GD
2
GD
2
of the total load which is accelerated and decelerated follows the expression below.
GD
2
= (Motor GD
2
) + (motor shaft conversion load GD
2
) [kg•m
2
]
The acceleration/deceleration time for each output range is calculated as shown below, using
the values obtained in 1) and 2).
3) Acceleration/deceleration time for constant torque range: t1
t1 =
1.03
×
GD
2
× N1
2
375 × Po
[s]
4) Acceleration/deceleration time for constant output range: t2
t2 =
1.03
×
GD
2
× (N2
2
- N1
2
)
2 × 375 × Po
[s]
5) Acceleration/deceleration time in deceleration output range: t3
t3 =
1.03
×
GD
2
× (N3
3
- N2
3
)
3 × 375 × Po × N2
[s]
Based on the above expressions, the acceleration/deceleration time: t from 0 to N3 [r/min] is:
t = t1 + t2 + t3 [s]
[Calculation example]
Calculate the acceleration/deceleration time from 0 to 10000[r/min] for an SJ-V5.5-01 motor having
the output characteristics shown on the right, when the motor shaft conversion load GD
2
is
0.2[kg
•m
2
].
Po = (Short-time rated output) × 1.2 = 5500 × 1.2 = 6600 [W]
GD
2
= (Motor GD
2
) + (load GD
2
) = 0.059 + 0.2 = 0.259 [kg•m
2
]
t1 =
1.03
×
GD
2
×
N1
2
375
×
Po
=
1.03
×
0.259
2
×
1500
2
375
×
6600
= 0.063[s]
t2 =
1.03
×
GD
2
×
(N2
2
- N1
2
)
2
×
375
×
Po
=
1.03
×
0.259
2
×
(6000
2
- 1500
2
)
2
×
375
×
6600
= 0.471[s]
t3 =
1.03
×
GD
2
×
(N3
3
- N2
3
)
3
×
375
×
Po
×
N2
=
1.03
×
0.259
2
×
(10000
3
- 6000
3
)
3
×
375
×
6600
×
6000
= 1.216[s]
Thus,
t = t1 + t2 + t3 = 0.063 + 0.471 + 1.216 = 1.75 [s]
0
N1
N2
0
Output [W]
N3
Po
Rotation speed [r/min]
Output characteristics for
acceleration/deceleration
Short-time rating
×
1.2
Constant
output range
Constant out
p
ut ran
g
e
Deceleration
range
0
1500
6000
0
2.0
6.0
8.0
4.0
Output [kW]
10000
15-minute
ratin
g
3.7
5.5
4.1
Continuous
rating
Rotation speed [r/min]
SJ-
V
5.5-01 out
p
ut characteristics
2.8