Servo motor is burning

[ESjaavik]

Do I understand you right that it is a cogged wheel driving a long toothed belt that goes from one end of the slide to the other?
The spring was too tight?? What spring?

Dhe drive. Is it one of these: http://www.nee-controls.com/dr_drivestext.html
I'll be very surprised if it does not in addition to what you mention have either settigs for motor characteristics, or simply a choice between some standard motor types.

The motor. Give the data from the label on the motor. Producer, type, etc. etc.

[Alex S.A]

ESjaavik,
You are right. It is a cogged wheel driving a long toothed rail and it is driving for all long rail. The equipement gotta two axis X and Y only. The system is one cutting machine for plasma and oxy fuel cutting process. The spring belong to the system and it works to keep the mechanical system without slack therefore keeping close the cogged wheel and the toothed rail. The motor I was wrong it is a model from CMC and it is model is: MT3528 - 450CF and the driver is from AMC but the controls I quoted above are the same.
Thanks

[Al_The_Man]

I assume you have a spring set up for maintaining the spur gear contact with the rack, normally excess gear pressure does not affect motor current that much. What is the model of the AMC amplifier, these usually have both a current limit setting, what is the dip switch set to on the amplifier? They usually have an output terminal that you can monitor current. It almost sounds like it is ok when the axis is being commanded to move, the following error is high so the command signal is such that the motor overcomes any excess loading, but if the motor is unable to reach the in position band setting then it will sit there with a constant command trying to reach the actual in-position setting. Which in my experience with these amps and motors is that you have a excess loading condition on the motor.
A way of setting the gain is to disconnect the motor gear from the rack and if you remove the +- command signal, the balance pot should be adjusted so that the motor is stopped and does not drift, next adjust the gain untill the motor growls and then back off the potentiometer 1/2 to 1 turn.
Re-conect the command signal and see if the overload occurs with the gear dis-engaged from the rack, this will see if the problem is mechanical.
Al

[ViperTX]

If the current is exceeding the limits then you have to suspect that something is causing the mechanism from moving, if the mechanism is moving slowly then it may be provinding too much torque for the servo to overcome, if you don't have any mechanical or load constraints does the servo run with a light load? Are you sure you have the servo wired correctly?

[Alex S.A]

What I could understand is: the servomotor, when I stopped it, goes on activited untill it stopped by itself. If the mechanical system is too tight, it is probably the motor will keep running, even "stopped", because it won't find the position for rest. Am I right? If so I think the problem will be solved for the system mechanical of equipament was tight beyond of normal because the spring was compressed too much. I monitoring the current of motor for all rack long while moving and the current changed in varying parts of rack.As i wrote now I am observing the equipment's behaviour.
Al,
I will get the information if the check you suggested was made by someone, I think so but I will get the assure information.

Alex S.A

[Al_The_Man]

Originally Posted by Alex S.A Hi guys is: Velocity, offset, gain and derivative gain. I did these adjustments at driver.

BTW the balance I mentioned is the same as offset.
Al

[ViperTX]

Yes, the servo is attempting to reach the location that the driver is telling it to seek, if the encoder is not moving then the motor is stalled and the driver will continue to supply current to the servo...eventually causing the problem you are encountering....one hot servo...until something fails or preset limits are reached.

[ESjaavik]

If it does not buzz, the problem is probably stiction. If it buzzes it may be slack or compliance.
If stiction, first try to find if there is a mechanical problem. Lack of lube, old gummy lube, worn parts etc. If not, try to lower your integral gain, I think that is the one you call offset. When lowered, it will be more "satisfied with" a position that is not exactly right. If increased, it will add current to try to remove the final small error. The longer the error persists, the more current it will add. This final positioning is probably not very important for your machine?

Maybe it just needs a good cleandown and relubrication?

[Al_The_Man]

Originally Posted by ESjaavik integral gain, I think that is the one you call offset.

Actually on the AMC amplifiers Offset is the zero or balance which should be adjusted for zero drift with no signal input.
Al

[Alex S.A]

The end position happens normally when I move the equipament in manual mode or when it, after execute a program, return the zero point. In these conditions it is not important. but if this adjustment influence the sheet will be cut, there will be more one problem. I will report you the behaviour of equipament. The last adjust I did were those I wrote in mechanical system.
Thanks for all help you have given to my problem. I am a new in CNC machines and I could learned much more after our chat in this site.

[Al_The_Man]

Good luck, let us know how it turns out.
Al

[Alex S.A]

hi everyone... Untill now the equipament is working fine
thanks
Alex Sandro