Chapter 11 Selection
11-17
(6) Selecting the appropriate motor from the continuous characteristics
Generally, the expressions (11-3) and (11-4) are calculated following the typical operation pattern,
and the motor is judged from the continuous characteristics. Because the Z axis is the vertical
axis here, the motor will be judged by the torque during an upward stop.
The unbalance axis torque during a stop is 60% or less of the stall torque (rated torque in
general-purpose motors). As shown in the following table, the only motor that satisfies this
reference is the HC153B. From the judgment in steps (4) to (6) it is the motor with the appropriate
Z axis.
Motor
type
Stall torque
(N·m)
Torque during stop
TU+TF (kg·cm
2
)
Load rate
(%)
Judgment Explanation
HC53B 2.94 4.39 149.1
×
An overload alarm occurs from just holding.
HC103B 5.88 4.39 74.6
×
There is no allowance for an acceleration/
deceleration operation.
HC153B 8.82 4.39 49.8
○
The torque during a stop is 60% or less.
11-5-2 Regenerative resistor selection calculation
Calculation is carried out in order with the Z axis as an example.
(1) Obtaining the generated torque
The deceleration torque required to calculate the regeneration energy is obtained.
• Upward stop deceleration torque: T
du
The amount of deceleration torque (=amount of acceleration torque) is first calculated using
expression (11-5).
T
a =
(J
L
+ J
M
) × N
95.5 × ta
=
(18.5 + 22.0) × 3000
95.5 × 120
= 10.6 (N·m)
The upward stop deceleration torque is obtained from the amount of deceleration torque,
unbalance torque and friction torque.
T
du = Ta − TU − TF = 10.6 − 4.3 − 0.09 = 6.2 (N·m)
• Downward stop deceleration torque: T
dd
The downward stop deceleration torque is obtained from the amount of deceleration torque,
unbalance torque and friction torque.
T
dd = Ta − TU − TF = 10.6 − 4.3 − 0.09 = 14.8 (N·m)
• Upward torque during dropping: T
s
The upward torque during dropping is obtained from the unbalance torque and friction torque.
T
s = TU − TF = 4.3 − 0.09 = 4.2 (N·m)
• Constant rate travel: L
Because the constant rate travel is not clearly described in the specifications, the axis stroke, etc.,
is considered, and the value used here is L=200mm.
(2) Obtaining the regeneration energy
Because the Z axis is the vertical axis, the regenerative energy is calculated separately for an
upward stop and downward stop.
• Upward stop regeneration energy: E
RU
This is obtained from expression (11-8).
E
RU = 5.24 × 10
−
5
· η · Tdu · N · td − Ec = 5.24 × 10
−
5
× 0.85 × 6.2 × 3000 × 120 − 40 = 59.4 (J)
• Downward stop regeneration energy: E
RU
This is obtained from expression (11-9).
E
RD =
2π · η · Ts · L
ΔS
+ 5.24 × 10
−
5
· η · Tdd · N · td − Ec
=
2π × 0.85 × 4.2 × 200 × 3
10 × 2
+ 5.24 × 10
−
5
× 0.85 × 14.8 × 3000 × 120 − 40
= 672.9 + 237.3 − 40 = 870.2 (J)
• Stop regeneration energy per cycle: E
R
This is obtained from expression (11-10).
E
R = 59.4 + 870.2 = 929.6 (J)
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