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View Full Version : Need Help! FANUC 0i-TB on KIA SKT21LMS- 410 Servo Alarm B Axis Excess Error



npolanosky
09-06-2018, 03:30 AM
Gents, I have a tough one for you (or maybe not, I might get lucky).


I'm getting a 410 Servo Alarm (B Axis Excess Error) on my KIA lathe with a FANUC 0i-TB.
I picked it up used about a year ago knowing it had some issues and it's only in the past month or so I've been able to get it into a shop with 3ph to power it. The subspindle axis driver and the B motor were out of the machine when I got it, so they had obviously run into this before.


Here's what happens:
Power up lathe.
Press Standby to enable servos and zero-return all axes.
Hydraulic pump comes on, servos get powered on, all is well.
B axis (subspindle linear axis) attempts to home.
B axis jerks + or - an inch or so and throws the 410 alarm.
No alarms on any of the servo amps themselves.


If I disable B by setting it's axis number to -128, I can jog the other axes (X/Z/C) but it will NOT run normally (can't run a program, turn on spindle, etc) presumably because it wants B at home for safety.


What I have observed:


B axis servo amp had missing solder on the main power bus bars inside. I repaired this, but it may indicate a problem with the driver. The subspindle servo does move though, so if it is damages it's (a) not throwing an alarm and (b) still moving the servo a fair bit.


The encoder reads position just fine, and after doing the P-CAN procedure and resetting zero with Param #1815 the home location and soft overtravels are in (at least the ballpark of, +/- 1/4") the right place.


The motor appears to move just fine and the tech I had out (who was also stumped by this) checked the motor and agreed it seemed ok. Resistance on all phases was the same, no ground issues.


I checked all of the parameters (yes, ALL of them. Took forever) and aside from a couple of minor discrepancies (backlash, machine on time, stuff like that) it all matched up.


Here's a video of the problem too, as well as a few minutes of me rambling about the aforementioned stuff:


https://www.youtube.com/watch?v=WCqKJaD2GZ4


So my question is, what do you folks think is the problem? Should I throw a B axis drive at it and hope that's all it is? Is it a software issue I can fix by changing parameters or resetting positions of something? Know how to fully disable the B axis so I can go about my regular turning and come back to this later? Have I stumped you as well?


Let me know, and thanks in advance. I'm happy to provide more info if I missed anything.

OkumaWiz
09-06-2018, 04:55 PM
Are you able to move the B-axis with the Paul handle? Or jog it? It also appears to be moving quite rapidly for a zero move if you slow the rapid rate down does it still want to jump like that? If you can move it with the Pulse handle or jog it the the axis should be ok. If not, you still have drive work to do. If they can move OK then you probably have a parameter issue.