Fagor APS-24, Hardware Manual

Page: 216 / 386

   Selection criteria
232
5.
S
E
LECT
ING CRI
T
ERIA
Asyn
ch
ronou
s
sp
indl
e mo
to
r an
d se
rvo
d
rive selectio
n
216
DDS
HARDWARE
Ref.1310
Calculation of acceleration and braking time
After selecting the mechanical characteristics and the power of the drive,
the acceleration and braking time is calculated as follows:
Calculation of power with intermittent load
Forming the drive to the right dimensions has to be done with the great-
est care when the application involves a periodical starting and stopping
operation, frequently repeated as in the case of threading with a miller.
For a cycle like the one shown in the figure F. H5/11 which includes accel-
eration and stopping, the equivalent effective torque T
R
of equation must
be within the S1 dimension given for the drive torque.
Calculations:
1.
With speed between 0 and 1500 rpm.
2. With speed between 0 and 6000 rpm.
PN
2

60
-------
2
JM NM
2

1000t
---------------------- kW
 

2

60
-------
2
0.13 1500
2

1000 0.5

--------------------------------

6.41 kW
 
1
 
= = =
PN
2

60
-------
2
JM NM
2
NB
2
+
 
2000t
-------------------------------------- kW
 

2

60
-------
2
0.13 6000
2
1500
2
+
 
2000 2.5

-------------------------------------------------------

10.89 kW
 
2
 
= = =
Constant torque
area:
(0 < N
M
< N
B
)
Constant power
area:
(N
B
< N
M
< N
max
)
Constant torque &
power area:
(N
B
< N
M
< N
max
)
J
M
Inertia of the load in kg·m² as viewed from the motor shaft
T
M
Rated torque at base speed in N·m
Nmax
Maximum motor speed in rpm.
N
B
Motor base speed in rpm.
N
M
Motor speed reached after a time period t in rev/min
F. H5/11
Periodic start-stop operation
t
1
2

J

M
N
M

60 T
M

------------------------------- s
 
=
t
2
2

J

M
N
M
2
N
B
2
–
  
120 T
M
N
B
 
----------------------------------------------------- s
 
=
t
3
t
1
t
2
+
 
2

J
M
N
M
2
N
B
2
+
   
120 T
M
N
B
 
--------------------------------------------------- s
 
= =
0
speed
0
torque
Tc
time
Nm
TL
Tp
-Tp
Tr Tf Ts
time
T
R
T
P
2
t
r
t
f
+
  
T
L
2
t
s

+
t
c
-------------------------------------------------------
Nm
 
=