Filter
Top Products
13 - 4
13. CHARACTERISTICS
13.3 Dynamic brake characteristics
13.3.1 Dynamic brake operation
(1) Calculation of coasting distance
Fig. 13.3 shows the pattern in which the servo motor comes to a stop when the dynamic brake is
operated. Use Equation 13.2 to calculate an approximate coasting distance to a stop. The dynamic
brake time constant
varies with the servo motor and machine operation speeds. (Refer to (2) of this
section.)
V
0
Time constant
Forced stop (EMG)
OFF
ON
Machine speed
t
e
Time
Fig. 13.3 Dynamic brake operation diagram
Lmax
60
V
0
JL
JM
t
e
1
....................................................................................................................... (13.2)
L
max : Maximum coasting distance .................................................................................................[mm][in]
V
0
: Machine rapid feed rate ........................................................................................ [mm/min][in/min]
J
M
: Servo motor inertial moment................................................................................. [kg cm
2
][oz in
2
]
J
L
: Load inertia moment converted into equivalent value on servo motor shaft..... [kg cm
2
][oz in
2
]
: Brake time constant ........................................................................................................................ [s]
t
e : Delay time of control section........................................................................................................... [s]
(There is internal relay delay time of about 30ms.)
(2) Dynamic brake time constant
The following shows necessary dynamic brake time constant for the equations (13.2).
0
14
16
2
4
8
10
6
12
0 500 1000 1500 2000 2500 3000
13
73
23
43
053
Speed [r/min]
Time constant [ms]
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.02
0 500 1000 1500 2000 2500 3000
73
23
43
053
13
Speed [r/min]
Time constant [s]
a. HC-KFS series b. HC-MFS series