Problem- brother tc-211 servo error

[Nksa]

hi guys!

I have a problem with my brother cnc tapping center-211. When I try to bring it to the machine zero point it starts (normally) by moving in Z+ direction, BUT, when it comes to its up most position I get the alarm SPINDLE SERVO ERROR!
I don't get it. This operation has nothing to do with the spindle servo?!

Nevertheless. I checked the manual to find that this alarm is classified under the "Serious troubles" and it says the reason for it is ABNORMAL RISE IN TEMPERATURE OF MOTOR REGENERATIVE BRAKING RESISTANCE FOR SPINDLE. The real abnormality is actually: how can there possibly be a rise in the temperature when the machine hadn't been turned on for at least two days before I got this problem!

Please help
Serious trouble
Niksa
replies can also be sent at: nikola@metalkej.com.mk

[Larken]

how can there possibly be a rise in the temperature when the machine hadn't been turned on for at least two days before I got this problem!

It could be a faulty temp sensor, telling the controller the temp is high when it really isn't.

[laserted]

Niksa - perhaps it could really be a spindle error? Not necessarily the cutting drive, but the "spindle as a whole".

Is this also the only error, or is it just the "last displayed one". Some controls hide a long list of errors, displaying only the last one on screen; you have to then look at a diagnostics screen for the complete picture.

I'm not a TC-specific guy, so what follows is a rather "generic" description - but it is something I experienced on one of my own machine tools....

Can you recall (prior to failure) if the spindle oriented itself for your toolholder pickup around that moment? I'm not sure how the TC spindles are set up (if they are a drive motor + index motor + clutch + encoder stack) - but most error messages are pretty generic, anyway. If it is trying to orient and fails, I would expect a machine tool builder to classify that as a "Spindle Error" for the operator's simplicity.
You may not have been able to see the orient move due to the location of the tool carousel, but it may have been an audible sound.
The reason I mention this is because I had just that happen on our Mazak; a "cleaner-helper" was doing his best to wipe down the machine, and "unintentionally" loosened the encoder cable for the spindle.

How to check it without tearing down the electronics could be a challenge, however. Machine tool builders don't typically provide that level of diagnostic support in the user-side of the control. (Now if you had retrofitted this machine to EMC or similar, I could probably help you out there...)

Does the DRO-view (Position view) provide a display for spindle angle? (Perhaps defined as the "C" axis, if you don't have a rotary on the table) If it can be spun by hand (careful here, OSHA is watching) and updates, at least you know the encoder feedback is operational.

The regen description is an interesting clue - in that if you have a failed servo or drive (for orientation), and that motor is not performing as expected (ie. commanded position does not match real position, resulting in a following error), and the drive tries to compensate....an overcurrent alarm could be thrown. Again, machine tool builders tend to "simplify" alarm codes and descriptions for the operator's convenience. (Which sucks for diagnostics by a competent individual!)

It may be a stretch, but if your spindle is not free to rotate (not going to suggest how), and a smaller servo motor is used to orient the spindle, when the "orient spindle to home position" command is issued (again, likely part of the z-home sequence) - the motor would not be able to move; the drive would spike power to it to try and get it to move, perhaps reach an overcurrent trip and disable. That energy (again it's a stretch) has to go somewhere, and depending on the servo type, may dump back into a regen or braking resistor. If the conditions were just right, perhaps it could then throw an overtemp alarm.

This is all generic speculation - however it is meant to assist in that just because the generally commanded sequence (z-home) doesn't initially appear to involve the symptom (spindle error), doesn't mean it isn't the root cause of the fault. The machine is trying to tell you something, before writing it off, I'd look into what it's saying.

Perhaps someone tried to help and was "cleaning" for you!

Cheers,

Ted.