Mazak H-400N spindle drive removal

The spindle will not rotate at all. We can freely rotate the spindle by hand and see right rpm's. We have determined conclusively that the drive is good by swapping with another identical machine. Motor connections are good and the motor passes megger checks. Voltage is making it to the motor. We are now preparing to remove the spindle motor for diagnosis/repair/replacement.

I was looking at the drawing and noticed a "power lock" where the motor couples to the spindle shaft. This looks like it may require removing the spindle to get at the bolts to remove this power lock. Can anyone comment on spindle motor removal? There's actually a written comment on the drawing saying that all of the highlighted (most of the assembly) has to be removed to get the spindle out, so it is confusing. If most of the assembly (which includes the motor rotor!) has to be removed to get the spindle out and the spindle appears to have to be removed to uncouple the motor from the spindle shaft, I'd say this is going to be trouble.

See this pdf file for the page I'm talking about. Item 33 is a "power lock" and it looks like spindle side bolts have to be removed to get at it.

What kind of spindle drive is this?
Are you getting an alarm when you run the drive?
If there are no alarms then it sounds like the command from the NC may never get to the drive. If CNC commands the drive, and the drive tries to run the motor, but the motor does not run, then there will be an alarm.

I am thinking from looking at the drawing that you are dealing with a H400N integral spindle,the rotor of your spindle motor comes out with the spindle cartridge still attached..... Your motor windings housing then come off from the back side of the column... Hope that helps some... Kind of a PITA... the rotor is balanced as an assy with the spindle.... i am confussed as to why you are going this route... is the spindle locked up or is it turning freely???if the windings all check good and your drive op checks in another machine you might be missing a condition for the processor to actually call for spindle rotation... the bearings in the rotor assy can cause the spindle to be locked up since it more or less is a direct drive not through a headstock with other gears and a drive motor lower in the column....

I should've explained it better. The spindle spins freely by hand. When I spin it by hand, it shows rpms on the drive and on the operator screen just fine. A good hand spin gets it up to 40-50 and slowly back down til it stops. I believe this rules out the plg. Megger checks showed good on the windings to ground and phase to phase. I have an identical machine to compare with. Also, I verified that after sending a command to spin, the motor leads have voltage. I scoped the voltage and saw that it changes behavior when going from low to high (y to delta by contactor action between the drive and the rotor). I called Mitsubishi tech support and went through it with them and they agreed that the motor must be bad.

jet@w&s: i have confirmed you are right about the structure of the spindle & drive. One person I talked to said that he worked with Mazak 19 years and only ever took the stator/field out 1 time and it has to be heated to be removed and placed from the casting. Can you confirm this?

Also, I'm removing stuff from the motor side prior to pulling the spindle and rotor out and I've hit a tough spot I need help on. In the following pic, I'm trying to extract item 373 using the 2 allens shown to push it off. It has a hydraulic fitting on it (opposite side) that is for the clamp/unclamp. Did I miss a step and that is why it doesn't want to come off? If I torque anymore I believe I'll bust the allens. Right now I'm letting some lube spray soak in. Here's the pic:

http://www.4micah.net/forumstuff/item373_mazakh400n.JPG

Got everything out

When we removed the rotor/spindle assembly, we noticed radial gouge tracks on the rotor surface as if something got in there and got ground up as the rotor spun. The rotor surface looks rough to me. Also, the bottom half of the stator windings has liquid accumlation. I'm not sure what the liquid is. This unit has through spindle coolant and also has coolant lines going through the stator housing to the spindle. The visible o-rings looked good.

http://www.4micah.net/forumstuff/mazak_h400n/stator.jpg
http://www.4micah.net/forumstuff/maz...n/spindle1.jpg

I just realized I never mentioned that there was a failure. It was some number (23 maybe) that would show up on the screen and drive that indicated rpm's were >50 off from the reference. New assembly install should be finished soon.