Chapter 2 Engineering Design of Servo Mechanism
23
Calculation and evaluation of effective torque
When the servomotor moves like fig. 2-10 pattern, the effective torque (T
t
) of 1 cycle is achieved by the
following equation.
T
Tt
CT
t
i
in
ii
(Nm)
(
1
2
)
However,
T
1
T
4
T
3
T
6
T
2
T
5
t
i
CT
Speed diagram
Torque diagram
Fig. 2-10 Evaluation of effective torque
(a) Evaluation of motor unit
T
t
< T
R
(Rated torque in the motor catalog) shall be formed.
Use the motor within 80% of motor rated torque because of encoder circuit thermal limit (70℃).
When the effective torque is 80% or more of motor rated torque, measure the temperature of encoder
circuit to check it is within the limit.
·············································································(3)
}····· Drive torque (T in equation (1)) (Nm)
}····· Deceleration torque (subtract friction torque from T in equation (1)) (Nm)
}····· Friction torque + particular torque (Nm)
······· Time of
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