AC servo motor not stationary in idle state

Hi

I am using a Chinese servo motor DORNA 130DNMA2-01D5CKAM (1.5kW, 2000rpm, 7.16Nm) with its compatible EPS-B1 series drive to feed metallic strip into a press machine. The servo is coupled thru a spider coupler to a set of metallic rollers which feed a predefined length.

The servo works fine except that after POSITIONing movement, sometimes the motor does not come to halt. The shaft would move 1 step clockwise and then 1 step anti-clockwise (repeatedly). This wrong positioning (+/- 1-2 millimeters) is disturbing further processing.

After some serious googling, I learnt that I need PID tuning for my system. I need some guidance how to do it.
 
Check page 127 of this manual all faults diagnosis are explained for a good and smooth troubleshooting...

Would do that If I was you !
Check if limit switch working properly if there is one installed...



Cheers
 
Looks like you wrote on another forum:

I would like to report you guys that the issue has been resolved.

After trying different options, I discovered that the issue was not with the servo or the drive. In fact, it was the roller set (directly coupled with the servo) which feeds the strip to desired length. Whenever the TENSION screws are over-tightened, the problem starts.

I could not diagnose it earlier because, I never faced such issue in another identical machine.

I would like to thank all the friends who participated in this discussion.


Can you explain if it is the case if yes why are you still writing same thread about this issue?

Cheers
James
 
Check page 127 of this manual all faults diagnosis are explained for a good and smooth troubleshooting...

Would do that If I was you !
Check if limit switch working properly if there is one installed...



Cheers
Thank you for your time.

I had already gone thru those faults but they all are described against a particular alarm code. And in my case, no alarm code is displayed on the drive.

Further, there is no limit switch involved in the system. The number of pulses required to achieve the predefined rotation (or length of the strip) is calculated on the basis of the diameter of the roller.
 
Looks like you wrote on another forum:

I would like to report you guys that the issue has been resolved.

After trying different options, I discovered that the issue was not with the servo or the drive. In fact, it was the roller set (directly coupled with the servo) which feeds the strip to desired length. Whenever the TENSION screws are over-tightened, the problem starts.

I could not diagnose it earlier because, I never faced such issue in another identical machine.

I would like to thank all the friends who participated in this discussion.


Can you explain if it is the case if yes why are you still writing same thread about this issue?

Cheers
James
Yes, it is the same case.
The issue was resolved temporarily. But after a few weeks, the problem reappeared. Since then I have been tweaking with roller to keep myself going. But sometime, it would not do any good only increase frustration. Even, I replaced the roller set. Presently, I am having same issue. I have done my best to set the tension of the roller but all in vain. That's why I joined this forum to seek help for PID tuning.
 
Yes, it is product manufacturing. You may watch a clip for the same when running in perfect order.
https://www.dropbox.com/s/ttseur3ou5aj98w/Press.mp4?dl=0

I have searched the user manual. It is a general manual which is usable for all DORNA EPS-B1 series of drives and compatible servos. There is no indication for the type/model of encoder for a specific motor. However, on page 66 they have described a procedure to display the type of encoder on the drive.

Right now, I am on leave and will resume on 11th. Then I will be able to check the drive and respond you.
 
From the procedure mentioned on page 66, I could only get the information that it is "Line-saving Incremental Encoder". However, I removed the encoder cover and found the maker WINMO.

IMG-20220810-WA0003.jpgIMG-20220810-WA0002.jpg
 
What is encoder feedback?


Simply put, an encoder is a sensing device that provides feedback. Encoders convert motion to an electrical signal that can be read by some type of control device in a motion control system, such as a counter or PLC. The encoder sends a feedback signal that can be used to determine position, count, speed, or direction.
 
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