[tanyiokhoe]

We have an unit of Citizen Cincom L16 w/o matainence and any manual, we face the uneven spindle speed during operation, is it the Fanuc 0T controller's parameter missed or some wrong value setting, we don't have any parameter list on hand, how can i solve the problem ? Thank in advance.

[CNCRim]

Is it spindle get faster as tool get closer to center? give us more detail.

[tanyiokhoe]

the spindle speed is changed suddenly, ex. 2000rpm to 3000rpm, when the tool is moving on Z-axis during OD turning

[neilw20]

Does the spindle motor use a tacho genrator for speed measurement?
As they get old brush type tacho generators need brushes replacing/serviceing.
The tacho generators are quite often directly on the end of the motor spindle.
Dismantle with care. Quite often VERY fragile internally.
Do not confuse with the shaft encoder driven from the main spindle, which is used to synchronise threading.
When the tacho is not working correctly, threading usually suffers wobbly pitch as well.

[tanyiokhoe]

thank you all for your reply. I still did not dismantle the machine yet, but addition information is the machine was made in 1998 and use Fanuc OT controller, main spindle's encoder is kuroda A86L-0027-0001 #203 (103?). Do somebody tell me whether the speed uneven's problem related to the parameter setting value or other else ? Is yes, how can i get a "true" copy or can i copy from the other exactly same type/model of machine?

[tanyiokhoe]

Hi, thank you all for your reply. How significant of the parameter value setting in relation to the spindle speed uneven problem? Before we go to dismantle the tacho and check the condition of brush, could we know more about the value setting. Actually we have 2 used unit with totally same model and type and manufacturing year, the maintenance guy told me that the machine has its specific value setting which has been optimimed by the supplier, we can simply copy the parameter from each other, is it right ?

[neilw20]

Why should the parameter have got wrong. Has it been fiddled with.
I assume the parameters are for PID constants for motor tuning.
If these have not been fiddled with they won't be the problem.
With the spndle running, at varying speeds, look at trhe tacho output with a CRO or multimeter. Is it clean and not varying?
Carefull hooking up a CRO. You must use differential input so that the CRO lead (earth) can't (possibly) damage the electronics.
Does these speed variation happen when you increase the load on the spindle?
I think the only time you can copy the parameter is if the two machines are identical in all respects at least as far as the motor and spindle are concerned.
If the machines are the SAME the parameters would be the same?
If you do change the value(s) make sure you write down the original.
Analyze the fault. Don't just try things.
Ther could be a fault in the cable shielding to the control panel speed control pot, or it is just getting old and flakey. Try different speed positions of the control.
You can overide the control with some M48, and eliminate the pot and its wiring that way. M49 Restores manual input.

[tanyiokhoe]

Dear Neilw20,
"I think the only time you can copy the parameter is if the two machines are identical in all respects at least as far as the motor and spindle are concerned.If the machines are the SAME the parameters would be the same?"

Today my guy told me that the problem machine is not exactly same in all inspects because the manufacturing year is different with the good one; and the spindle motor seem like other, too. Thank again for your value comments and i quite sure you are familiar with servo control and trouble shooting.
Beside that, the machine is bought about 2 months ago by the top management, i don't know the running condition before it shipped to the factory that until my subcontractor is going to try the machine and try to run it in their premise.
I have attached a electrical schemetic daigram for spindle motor and its control from the good machine for your reference.

[neilw20]

This looks like a variable frequency drive with no speed feedback.

I think a component in the power drive circuitry in the main spindle drive unit is possibly your problem.
TURN ALL POWER OFF AND REMOVE ISOLATE POWER BEFORE NEXT STEP

Check all internal connections on and around outputs UVW and inputs RST.
It could be a loose connection, or an intermittent power contol device.
Also check all of the wiring going to the motor for bad crimps/connections.

Look at voltage phase to phase with an AC mutltimeter on UV, VW and UW,
or easier still, some light bulbs as detailed below.
All of these three voltages measured while motor is running under load should not change noticbly.

Try putting a (3) 240v-40W light globes, on on each of UV, VW and UW.
The 3 should always be the same brightness.

If one of the lamps is different you have a problem on one of the phases,\.
If all of the lamps vary together, you have a problem on either the drive cuircuitry or power suuply side.

Keep testing...

[tanyiokhoe]

Thank again of your immediate reply, i already inform my guy to monitoring it. Have a nice weekend.

[neilw20]

Thank again of your immediate reply, i already inform my guy to monitoring it. Have a nice weekend.

U 2.:cheers: