Having a problem with my old Kitamura VMC DC spindle motor and/or drive.
1981 Kitamura Mycenter-2
Fanuc 6MB control
Approx 7 hp DC spindle motor w/ Fanuc 3 spindle drive
Running on 3 ph. rotary. conv.
Was running an easy cutting UHMW job when machine shut down.
Cycle power and come up to Not Ready screen.
Find that 2 out of 3 main fuses (35A) to spindle drive are open.
Inspect motor brushes and find a LARGE amount of carbon dust and copper
dust accumulated on brush holders. Enough copper dust to cause a short.
Replace fuses...un-hook motor leads from drive....powers up fine.
(I do not issue a spindle command )
The commutator is worn about .015"/side, slightly gouged, not burnt and not bridged across segments.
I have cleaned/inspected the brushes about 6 months ago and they were dusty with carbon dust but not out of the norm. I polished/cleaned the commutator and inspected for any bridging. I do this fairly routinely.
I just finished a mild steel cutting job that taxed the spindle motor for about 20 hours total (not continuous).
Machine sees alot of 18 hr. continuous runs cutting UHMW
I have gotten occasional spindle overcurrent alarm in the past. Usually associated with an M3 command.
I have recently been running a program that requires me to manually lock the spindle. 3 times I failed to unlock the spindle and got the overcurrent alarm when trying to orient for the tool change.
Actions so far:
Pulled the motor, disassembled and cleaned everything. Turned the armature and scraped the arm. slots. Replaced bearings while torn down.
Megged the field windings which show OK.
Pulled out the motor leads from drive to motor and inspected, seems OK.
Replaced tach-generator wires since they seemed pinched and bent in areas.
Powers up OK
Get a "Servo 401" when issuing a spindle command. Spindle makes about a 45 deg. turn and shuts down. Once got an Overcurrent LED but mostly no LEDs lit.
Kitamura tech says that the 401 error combined with the copper dust on the brushes indicates that motor will need rebuilt.
The rebuild cost is enough that it may be time to part ways with the machine.
One thing that I notice and do not recall before. The EMG relay LED is lit as soon as the power is turned on. Is this indicating that there is an emergency stop situation?? I have cycled the Estop button and made sure the toolchanger was at home positions.