Kollmorgen Cartridge DDR motor running off AB PowerFlex 755

[DSCNT_dblCheck]

Im trying to diagnose a loud vibrating/humming noise coming from my companies Kollmorgen Cartride Direct-Drive Rotary motor.

The motor is being used to drive a spindle for the purposes of running balancing tests on wheels.

being ran using an allen-bradley powerflex 755.

Any suggestions/theories as to what i may be experiencing or how to troubleshoot. I've tried numerous things already.

The noise did go away for about a day, ALL ON ITS OWN, but upon cycling power to the machine the noise resurfaced. Any help is very appreciated. THank you,

-DSCNT

 

[kamenges]

Is this a system that has worked before and now it doesn't or is this a new application?
If working before, has anything mechanical changed on the system?
How "pure" is the vibration? Does is sound more like a harsh growl or is it more like a 60Hz hum from a speaker?

Keith

 

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Yes it worked when we were doing testing and buy-offs, now that the machine has been transported and installed at the customer, we are experiencing this issue.


It ranges from a loud knocking noise, to a very veryvloud humming/rubbing/skipping. Much more louder than a 60Hz hum from a speaker.

The noise eventually went away about 3 days ago while troubleshooting, but after cycling power to the machine the noise came back.

 

[kamenges]

Is this the motion variant of the PF755 or is it stand-alone? If the motion variant, are you operating as a position or velocity axis?

If I were in your shoes I would confirm that nothing went wrong with the rotor to shaft coupling. If that and other mechanical aspects look good and it is the motion variant of the PF755 I would perform an autotune through the axis properties dialog. Assuming everything is tight mechanically it sounds to me like the axis is tuned VERY close to instability and the system lost a little natural damping after operating for some time.

My comment about the speaker hum has less to do with volume and more to do with purity. I guess think more in terms of the sound a VERY large tuning fork would make. A softer, purer sound than a harsh growl. I'm not sure a PF755 is even capable of setting up a "controlled" (non-saturated) sinusoidal oscillation between the motor and the load. The loop closure bandwidth may not be high enough. Direct drive motors with the rotor coupled directly to the load shaft and no other power transmission components have been known to do that if the load shaft is a bit spongy for the available motor torque/load inertia combination.

Keith

 

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Well, noise is gone

Master calibration
Accuracy & linearity
Tool comp
And repeatability

Is passing with flying colors.

I'm done and over it moving on to my next job. Thanks everyone for your replies. Hopefully I never have to return to this thread again ��