12 - 27
MELSEC-A
12 CONTROL AUXILIARY FUNCTIONS
12.4.2 Torque limit function
The "torque limit function" limits the generated torque to a value within the "torque limit
value" setting range when the torque generated in the servomotor exceeds the "torque
limit value".
The "torque limit function" protects the deceleration function, limits the power of the
operation pressing against the stopper, etc. It controls the operation so that
unnecessary force is not applied to the load and machine.
The details shown below explain about the "torque limit function".
(1) Relation between the torque limit function and various controls
(2) Control details
(3) Precautions during control
(4) Setting the torque limit function
(1) Relation between the torque limit function and various controls
The following table shows the relation of the "torque limit function" and various
controls.
Control type
Torque limit
function
Torque limit value *
1
Machine zero point return control
Cd.101
Torque output setting
value*
2,
*
3
Zero point
return
control
High-speed zero pint return control
1-axis linear control
2-axis linear interpolation
control
1-axis fixed-dimension
feed control
2-axis fixed-dimension
feed control (interpolation)
Position
control
2-axis circular interpolation
control
Speed control
Speed/position changeover control
Cd.101
Torque output setting
value*
2
Current value change –
Main
positioning
control
Other
control
JUMP command –
–
JOG operation
Manual
control
Manual pulse generator operation
Cd.101
Torque output setting
value*
2
: Set when required (Set to " – " when not used.)
– : Setting not required (Setting value is invalid. Use the initial values or setting values
within a range where no error occurs.)
*1: Indicates the torque limit value to be transferred to the servo amplifier at a start of
the corresponding control when the "
Cd.30
New torque value" is "0".
*2: When the "
Cd.101
Torque output setting value" is "0" or greater than the "
Pr.18
Torque
limit setting value", the torque is limited at the "
Pr.18
Torque limit setting value".
*3: After the "
Pr.49 Creep speed" is reached, the torque is limited at the "
Pr.56
Zero
point return torque limit value".
At a start of the corresponding control, the "
Cd.101
Torque output setting value" is
referred to, and its value is transferred to the servo amplifier. However, if the "
Cd.101
Torque output setting value" is "0" or greater than the "
Pr.18
Torque limit setting value",
the "
Pr.18
Torque limit setting value" is transferred to the servo amplifier.