Mitsubishi Electric MDS-D-SPJ3 Specification Manual page 195

MITSUBISHI CNC
7 Selection
(2) For servo unbalance axis
The regenerative energy differs in the upward stop and downward stop for an unbalance axis. A
constant regeneration state results during downward movement if the unbalance torque is the same as
or larger than the friction torque.
A regenerative state only occurs when deceleration torque (downward torque) is generat-
E 5.24× 10
RU
ed.
Upward
stop
A regenerative state occurs even during constant rate feed when the upward torque Ts during drop-
ping is generated. Calculate so that Ts = 0 when Ts is down-
E
RD
ward.
Down-
ward
stop
The regenerative energy per cycle (E
E = E + E (J)
R RU RD
(Example)
Using a machine tool vertical axis driven by an HF154 motor, reciprocation is carried out with F30000 at
an acceleration/deceleration time constant of 100ms for a distance of 200mm. Obtain the regenerative
energy per reciprocation operation in this case.
Where:
Servo drive unit
Travel per motor rotation
Upward stop deceleration torque
Downward stop deceleration torque
Upward torque during downward movement
Using expression (7-14), the upward stop regenerative energy E
E = 5.24×10
RU
The acceleration/deceleration distance required to accelerate at the 100ms acceleration/deceleration
time constant to 30000mm/min. is as follows:
3
2 × 60 ×1000
Therefore, the constant speed travel is 150mm.
The downward stop regenerative energy E
E
RD
Thus, the regenerative energy per reciprocation operation E
E = 227.2 + 601.2 = 828.4 (J)
R
7 - 16
Regenerative energy
-5
T N t Ec
･ ･
du d
η
T N
du
t Ec
d
2 T L
･ ･ s
- 5
5.24 × 10
Δ S
η
Ts
L
ΔS
T N
dd
t Ec
d
) is obtained using expression (7-16) using one reciprocation as one cycle.
R
-5
×0.85×20×3000×100 - 40 =227.2 (J)
× 100
25 mm
2 × 0.85 × 3 × 150
5.24 × 10
10
J
:Motor reverse efficiency
:Upward stop deceleration torque
:Motor speed
:Deceleration time (time constant)
:Unit charging energy
･ ･ T N t Ec J
dd d
:Motor reverse efficiency
:Upward torque during dropping
:Constant speed travel
:Travel per motor rotation
:Downward stop deceleration torque
:Motor speed
:Deceleration time (time constant)
:Unit charging energy (J)
: MDS-D-SVJ3-20NA
: 10 mm
: 20 N•m
: 30 N•m
: 3 N•m
is as follows:
RU
is obtained using the following expression (7-15).
RD
- 5
× 0.85 × 30 × 3000 ×100
is as follows:
R
••• (7-14)
(N•m)
(r/min)
(ms)
(J)
••• (7-15)
(N•m)
(mm)
(mm)
(N•m)
(r/min)
(ms)
(J)
••• (7-16)
40 601. 2 J