The Servo Motor Vibrates; Poor Speed Accuracy (Unstable Speed Of Servo Motor) - Mitsubishi Electric Melservo-J5 MR-J5 Series User Manual

The servo motor vibrates

• The servo motor vibrates.
Possible cause
1.
The servo gain is high. Or the response of the
auto tuning is high.
2.
The machine is vibrating (resonating).
3.
The load side is vibrating.
4.
Noise entered the encoder cable, causing the
miscount of the feedback pulses.
5.
There is a backlash between the servo motor
and machine (such as a gear and coupling).
6.
The rigidity of the servo motor mounting part is
low.
7.
The connection of the servo motor is incorrect.
8.
An unbalanced torque of the machine is large.
9.
The eccentricity due to a core gap is large.
10.
A load for the shaft of the servo motor is large.
11.
An external vibration propagated to the servo
motor.

Poor speed accuracy (Unstable speed of servo motor)

• The speed accuracy is poor. (The servo motor speed is unstable)
Possible cause
1.
The servo gain is low. Or the response of the
auto tuning is low.
2.
The servo gain is high. Or the response of the
auto tuning is high.
3.
The torque is insufficient for the large load.
4.
An unintended torque limit has been enabled.
5.
The setting value for the torque limit is
incorrect.
6.
For a servo motor with an electromagnetic
brake, the brake has not been released.
7.
The command from the controller is unstable.
8.
The power supply voltage is lower than
specifications.
1 SERVO AMPLIFIER TROUBLESHOOTING
104
1.4 Trouble which does not trigger an alarm/warning
Check/action method
Decrease the servo gain, and then check if the trouble is solved. Or, decrease
the value of [Pr. PA09 Auto tuning response].
Perform one-touch tuning or adaptive tuning. Or, set the machine resonance
suppression filter.
Perform vibration suppression control tuning. Or, set the vibration suppression
control.
On the status display ([A]) or MR Configurator2, check if numerical values of
the cumulative feedback pulses are skipped. Take countermeasures against
noise, such as laying the encoder cable apart from the power cables.
If the coupling and the machine are nearly broken, or there is a backlash,
perform an inspection and maintenance.
Increase the rigidity of the mounting part by increasing the board thickness,
reinforcing the part with ribs, or other means.
Check the U/V/W wiring.
Refer to "Connection example of power supply circuit" in the following manual.
MR-J5 User's Manual (Hardware)
As the servo motor speed changes, check if the vibration also changes. Adjust
the balance of the machine.
Check the mounting accuracy of the servo motor and machine.
Make the load for the shaft of the servo motor equal to or less than the
permissible load of the servo motor.
Refer to "Standard specification list" in the following manual.
Rotary Servo Motor User's Manual (HK series)
Prevent the vibration from the external vibration source.
Check/action method
Increase the servo gain. Or, increase the value of [Pr. PA09 Auto tuning
response].
Decrease the servo gain, and then check if the trouble is solved. Or, decrease
the value of [Pr. PA09].
Check the instantaneous torque on the status display ([A]) or with MR
Configurator2. If the torque reaches the maximum torque or the torque limit
value, reduce the load or replace the servo motor with a larger-capacity servo
motor.
On the status display or MR Configurator2, check if TLC (Limiting torque) is
turned on. Cancel the torque limit.
Refer to "Torque limit" in the following manual.
MR-J5 User's Manual (Function)
Increase the torque limit value.
Refer to "Torque limit" in the following manual.
MR-J5 User's Manual (Function)
Turn on the electromagnetic brake power.
Review the command from the controller.
Or, check for disconnection or other failure in the Ethernet cable.
Adjust the power supply voltage within the range of specifications.
Model
[A]
[G]
[WG]
Model
[A]
[G]
[WG]