MHT258a (Engl.)11-7
If the actual torque surpasses the rated torque, the following items should be reviewed.
・Slightly reduce the frequency of acceleration and deceleration.
・Review decel. method or decel. ratio, etc. and set feed speed appropriately.
・If motor torque is generated even during stop, a mechanical equipment system should be selected so as to minimize the necessity for
torque at stop.
・To maintain motor response at a satisfactory level, it is recommended to restrict the moment of inertia load within the twofold value of
moment of inertia of motor rotor. If higher frequent operation is absolutely required, the moment of inertia of load should be further reduced.
(g) Regenerative brakign power
(i) Horizontally moving, deceleration
P
1
= 0.105 × T
DC
× N
10
× ( 1 / 2 ) [W]
Where,
T
DC
= Decel. torque [ N・m]
N
10
= Speed at decel. duration [ r/min ]
(ii) Vertically, lowering
P
2
= 0.105 × T
L0
× N
20
[W]
Where,
T
L0
= Load torque at lowering [ N・m]
N
20
= Speed at lowering [ r/min ]
(iii) Mean braking power per cycle
Where,
t
1
, t
2
: Decel. time during P
1
/P
2
operation
(3) Examples of calculation for model type selection
Selection of the output of the motor used for driving the table (horizontally moving body) shown below is exemplified here.
= 20 x 10 x 500
Mass : 20kg
For capacity selection, calculation is required in the following selection procedure.
(i) Moment of inertia of load via conversion into motor shaft
a) Movable part (table) (J
L1
)
()
J
L
W
BP
GL kg m
1
3
2
2
3
2
2
32
1
2
10
20
1
2
10
10
11 005 10=×
ì
í
î
ü
ý
þ
×= ×
ì
í
î
ü
ý
þ
×=×
−
ππ
・/. [ ]
Where, W : Mass (weight) of table
b) Ball-screw (J
L2
)
()
J
L
BL BD
GL kg m
2
33
4
2
3
33
4
2
32
32
10 10
785 10
32
500
10
20
10
11 006 10=××
ì
í
î
ü
ý
þ
×=
××
××
ì
í
î
ü
ý
þ
×=×
−
ππ
・
ρ
.
/. [ ]
Where, ρ : Density of ball-screw (assumed as 7850 [kg/m
3
])
thus, J
L
= J
L1
+ J
L2
= 0.11 × 10
-3
[kg・m
2
]
P
1
× t
1
+ P
2
× t
2
[W]
t
CYC
P =
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