QUICK-TURN 15 Turret index won't index

[E-Stop]

One of our QT-15 Lathes stopped indexing tools. The turret will unclamp and just sit there until it gets a "Time Exceeded" alarm. Mazak told us the hydraulic Index Motor was probably bad and should be replaced.

We pulled the motor and sent it out to be rebuilt and was told that all of the internal components were badly worn but nothing broken. They completely rebuilt it ($3,000)!

We put the hydraulic motor back in and get the same problem. We've checked all of the corresponding X data bits and all of the Y inputs and outputs and everything is reading what it should. The relays are working fine. We suspected a bad solenoid so we swapped them with one of the other lathes. The solenoids work fine on the other lathe but we still have the same problem with the 'bad' lathe.

We've pulled the solenoids off (one for clamp/unclamp and one for cw/ccw rotation) and when air (90psi) is blown thru the manifold, the turret clamps/unclamps and the turret spins freely like a pinwheel on a windy day.

We've pulled the motor back off and set it on a table with the hydraulics hooked up and if the solenoid is manually energized the motor turns just fine in both directions.

So I think we have eliminated the possibility of a mechanical bind. And we have traced all of the electrical components from the control to the solenoids and everything is working as it should.

We have talked to tech support at Mazak and they have guided us thru most of the above procedures. But now they, too, are stumped. We have a company that does maintenance on our Mazaks when it is beyond our capabilities and we have called them and they suggested many of the same things and they are stumped too.

So now I am pleading my case to the real experts. Have any of you had this type of problem or have any thoughts on what to try next? The machine has been down for almost a month now and it's going to get us in trouble real soon.

 

[wippin' boy]

you should be able to unclamp from the control page
and then force rotation by jabing the hydraulic valve that directs flow to hyd. motor
if you can do this unclamp confirmation is my first thought
encoder half a station off is next
had all kinds of trouble with a qt15 one time
did all the same things(including the 3 grand)
ended up being a polluted hydraulic system
the thing would work a bit then quit again
little pieces of black crap(disintegrated o-ring i suppose)were getting the valve that directs rotation
put a filter inline hanging just in front turret hoses
working smoothly 2 years later
probly just jinxed the piece of crap

 

[wippin' boy]

after reading your post again
i wonder about some kind of interlock
are you geting the cc or ccw signal?
are you getting voltage to coil?
voltage or no voltage AT THE COIL is critical to figuring this out

 

[E-Stop]

Yes, I can unclamp the turret from the control but when I jab the valve the turret does not move. That's why we took the motor back out and bench tested it. On the bench we can make the motor turn both directions by jabbing the valves. This made us believe there was a mechanical bind. So we removed the valve and blew air into the ports and the turret spins. That eliminates the mechanical bind theory.

And Yes, we are getting the cw and ccw signals thru the inputs. We have watched the inputs in the ladders and everything seems to be working correctly. We measure about 6 to 8 volts at the coil when at rest and about 100 volts when the button is pressed, so that seems OK.

And we aligned the encoder per Mazak procedures:
1) Set the turret to the number 1 position.
2) With the encoder removed, rotate until the red LED lights up.
3) Re-install the encoder.

Still something just isn't working.

 

[cnctoolcat]

We have watched the inputs in the ladders and everything seems to be working correctly.

You must verify positively every related input and output. The electrical manual has the ladder diagram. Use the ladder and the bit monitor on your screen to find the problem.
If nothing electrical/control related, then it must be mechanical.
From what you are describing, the hydraulic motor works on the bench, but not in the machine.
Sounds like maybe the motor/gearing are getting bound when installed?
Or, maybe your hyraulic clamp piston has seized to the turret shaft, preventing the turret shaft from rotating?
Gotta get more proof for the encoder. Just because it lights up on Tool 1, doesn't mean it's good. Again, bit monitor can help here.
Good luck.
Keep us posted!

 

[E-Stop]

You must verify positively every related input and output. The electrical manual has the ladder diagram. Use the ladder and the bit monitor on your screen to find the problem.

We have verified every related input/output using the ladder diagram and the bit monitor. I'm not real good with ladders but my partner is pretty well versed. And he verified his conclusions with Mazak.

The clamp/unclamp is working fine and as I said, if we remove the solenoid valve and blow air into the manifold, the turret spins. We have voltage when and where it is supposed to be and no voltage when not. All appears to be working properly, mechanically and electrically but something is still out of kelter.

Oh, and the encoder. While we had the motor out on the bench, we manually rotated the turret and watched the bit monitor and the encoder was reading each tool position correctly.

 

[dcrace]

Try swapping the supply and return lines either at the back of the turret or the pump side... we recently had to rebuild the pump and motor on our QT-8, when we put it back together it did the same thing! Once we swapped the lines it worked fine.

 

[E-Stop]

Yeah, we thought that too, even though the hoses were clearly marked (color-coded). So we swapped them and then the turret would stay unclamped all of the time and it still wouldn't rotate. So we swapped 'em back.

 

[cnctoolcat]

Maybe it's a weak hydraulic motor? Strong enough to turn over on the workbench, but too weak to rotate turret...
I "rebuilt" a QT15 turret motor once. For $10. 2 small ball bearings had failed.
At the time, Mazak quoted $6K for new motor.
The solenoid valve has to send fluid to motor when you force the valve. If pressue goes to the motor, and the motor doesn't rotate, IMO, it's got to be the motor.
Or a binding condition when installed.
You should be able to take apart the hydraulic motor...and reassemble. A good visual inspection of the motor's inerds will reveal if you have a problem with the motor.

 

[E-Stop]

We just spent $3000 on getting the motor rebuilt and we've talked to the guy that did it and he assured us that he tested it under a greater load than the turret would be. He is more than willing to re-test it if we send it back. However, if we open it up the warranty is void.

So, since we have been everywhere else with no success, the boss has a theory. He figures that since every time that we have rotated the turret, either by hand or by blowing air thru the manifold, that there really was no outward force applied when the turret was unclamped. His theory is that when the hydraulics are used to unclamp the turret, it is then that something binds. Kinda makes sense.

Enough sense that the guys started removing the turret this afternoon to see what there is to see.

 

[cnctoolcat]

Yeah, the unclamping is by hydraulic force just like the clamping is. The pressurized unclamping of the turret could be binding the turret shaft, preventing turret rotation.
The turret shaft rotates inside the hydraulic piston. The piston bore is grooved helically. These spiral grooves are pockets for holding grease.
A good cleaning and greasing here could help.
There is the possibility the turret shaft, and/or the piston are worn excessively. The fit should be fairly precise, to maintain the necessary thin grease film that allows the turret shaft to rotate within the piston.
Also, excessive play between turret shaft and piston lets the turret drop, or sag, when uclamped.
I made a cylinder, gland, and piston for a '85 QT10N. Took maybe 12 hours and $100 material.
Mazak wanted like $5K for the set.

 

[RyanV]

I may not know mazatrol but one thing I know is hydraulics. I wonder what type of hydraulic motor it is. Maybe if it is a piston type you will have a case drain. Meaning 2 hoses going in for rotation and another for draining the case pressure. Check to see if you have this extra hose and remove it to see if your getting alot of oil out of it. This would mean the case or seals have problems. The other thing would be on this type is a distributor that the 2 hoses go to. If this is taken apart and not put back together you will have big time nightmares. Most will have a disk inside the spins and you have to get it perfect or your up a creek. Like someone else said flip the 2 hoses for rotation to see if that helps.. that would mean mostlikely a distributor problem. Hope that helps. What brand of motor is it?

 

[Steve@Reliance]

On our QT-10, there is a plunger and a little lever inside the turret that makes the prox switch when the turret unclamps. If the turret coupling get knocked out far enough, the plunger binds up and won't make the switch. The turret unclamps but the control dosen't get the signal to index.

 

[E-Stop]

RyanV-
I don't think it's that kind of hydraulic motor. There isn't any drain hose. There are two hoses attached to a manifold. One is for supply, the other for return. A solenoid valve controls the direction of flow and thus the direction of rotation. Swapping the hoses doesn't help.

Steve-
Not getting a signal to rotate is kinda where I was looking when this all began. Watching the bit monitor and the ladders, it seems that all of the switches are being made and all of the signals are getting sent. And when we had the motor out to bench test it, the motor would turn when commanded by the control. But there again, the turret was not being unclamped by hydraulics.

 

[cnctoolcat]

Hey E-stop-
The turret shaft also rides in at least 1 large bearing, located behind the clamp cylinder. This bearing may be bad, not letting the turret shaft rotate.
Pull the turret, pull the hydraulic cylinder. Dismantle the cylinder and check for unusual wear.
Be careful when installing the hydraulic cylinder back into the turret housing. There is 2 little o-rings that seals the fluid passages between the back of the cylinder and the turret housing. Make sure these o-rings stay in place (use some super glue if necessary), and make sure the cylinder is installed in the correct orientation to line the port holes up.
You should replace all o-rings upon reassembly.
With the cylinder out of the turret housing, you should be able to freely rotate the large bearing(s) that the turret shaft rotates in.
The hydraulic motor is very powerful. Thus, if something is binding up, it has to be a heck of a bind.
Let us know what you find.

 

[E-Stop]

We disassembled the turret, cylinder, piston and all that stuff yesterday. Really didn't find anything that looked bad. All parts were in surprisingly good condition. We've cleaned it all up, re-greased it, put all new o-rings in and are going to put it all back together this morning.

Since we don't feel as though we "fixed" anything, I think we are going to have the same problem when we get her back together. But maybe not.

 

[RyanV]

I just read your post again about the price of the motor. 6K? Is the shaft and gears gold plated? Solid platinum? Whats Mazaks parts return policy if you bought this and it didnt work?

 

[cnctoolcat]

The hydraulic index motor for Mazak cnc lathes is a special design. The motor istelf has internal porting to control the clamp/unclamp and rotation sequence. These are very tightly syncronized, as the clamp/unclamp and rotate occur in about .2 (yes, that's point 2 tenths) second for a 1-station index.

A Japanese company makes these for Mazak, and will not sell direct. The motor has a "toroid" style power mechanism.

If you need a new motor from Mazak, then $6K is what you pay. That's why the rebuild cost is $3K.

 

[RyanV]

Ok I think ive decieded to sell my 510CII just for parts. I need beer money. Toroid or do you mean hemmoroid?

 

[wippin' boy]

did you find anything ??