3-25
3-5-7 Torque Limit Function
H
Function
•
This function limits the Servomotor’s output torque.
•
This function can be used to protect the Servomotor and machine system by preventing excessive
force or torque on the machine system when the machine (moving part) pushes against the work-
piece with a steady force, such as in a bending machine.
•
There are two methods for limiting the torque:
1. Limit the steady force applied during normal operation with user parameters Cn-08 (forward torque
limit) and Cn-09 (reverse torque limit).
2. Limit operation with external signals connected to pins CN1-11 (PCL: forward current limit input)
and CN1-12 (NCL: reverse current limit input). Set user parameters Cn-18 (
forward rotation external
current limit
) and Cn-19 (reverse
rotation external current limit
).
H
Parameter Settings
D
Method 1: Limiting the Force Applied During Operation
•
User Parameter Settings
PRM
No.
Parameter name
Factory
setting
Unit
Setting range
Explanation
Cn-08 Forward torque limit
Maximum
torque
%
0 to maximum
torque
This parameter sets the output torque
limit for the forward direction (as a
percentage of the rated torque).
Cn-09 Reverse torque limit
Maximum
torque
%
0 to maximum
torque
This parameter sets the output torque
limit for the reverse direction (as a
percentage of the rated torque).
Note Set these parameters to the maximum torque (the factory setting) when the torque limit function
isn’t being used.
D
Method 2: Limiting Operation with External Signals
•
Setup Parameter Settings (Bit 2 of Cn-02 = 0)
Set bit 2 of Cn-02 (the input command mode) to “0.” When bit 2 is “0,” control input terminal CN1-11
will be PCL (forward current limit input), CN1-12 will be NCL (reverse current limit input), and it will
be possible to use the external current limit function.
•
User Parameter Settings
PRM
No.
Parameter name
Factory
setting
Unit
Setting range
Explanation
Cn-18 Forward rotation
external current limit
100
%
0 to maximum
torque
This parameter sets the output torque
limit (as a percentage of the rated
torque) when the forward rotation cur-
rent limit is input.
Cn-19 Reverse rotation
external current limit
100
%
0 to maximum
torque
This parameter sets the output torque
limit (as a percentage of the rated
torque) when the reverse rotation cur-
rent limit is input.
Operation
Chapter 3