Fanuc 0T - Tool Turret Wrong Position - Takang TNC-25-S Lathe

[VincePlasma05]

Hi Guys,

I hope you can help me out or point me in the right direction. We have a Takang TNC-25-S lathe with an old Fanuc 0T. The tool turret is a Duplomatic BSV-N (electronic, not hydraulic) with absolute encoder. Our problem is as follows :

* When doing a tool change (JOG mode), the turret indexes to a tool position, 2 positions from the selected position, if we select T0101 then the turret moves to T0303, for any combination - always 2 positions out of sync.

* I've tested all electrical connections to the tool turret and it's encoder as per Duplomatic's data sheet, all are correct. The proximity sensors, solenoid indexer and motor brake all function correctly.

* I have located the machine builders diagnostic setting numbers that reflect the encoder's position "D0460" (corresponding to the correct position values as stated in Duplomatic's data sheet for the tool turret), the selected tool number "D0461" (I can see the value change as I select different tool positions on the operators panel)

* Once I select a tool position on the operators panel and press tool start, the turret indexes, on the diagnostic screen, the encoders value (diagnostic # D0460) is that of 2 tool positions onward and not the selected tool position.

* I've tried to reset the turret by turning it to the correct tool position by hand, when disengaging the turret motor's brake and indexing solenoid. I watch the diagnostic setting D0460 as it changes to the correct tool position value corresponding to the selected tool position as on the operators panel. I reboot the control, zero the Z and X axis and try to manually change the tool position in JOG mode - but the problem remains, the tool turret indexes and goes to a tool position 2 places from the selected tool position.

* I've also tried to change the value of the tool selected diagnostic to match that of the encoders, without any success.

Is there a counter parameter or diagnostic setting which I can search for and change to force the tool turret to only increment/decrement the necessary amount of times to fix this indexing issue ? I've tried to contact the machine tool builder but unfortunately the machine is too old for their records/personal to be able to assist.

I can upload photos/parameters/diagnostic settings if any of it will help. I can access the ladder as well on the machine and take some photos ?

I will appreciate any advise - everything else on the machine seems to be working perfectly, this is the last unfortunate problem that's got me stuck. It would be a shame to let the machine go just because of this.

Thank you.

[VincePlasma05]

Here are 2 photos of the Duplomatic BSV-N tool turret's wiring diagram and the cycle of tool changes. I will be uploading some photos later of the diagnostic screen and the operators panel.

Thank you.

Attachment 437593

[Jim Dawson]

In the OT control there is a way to home and reset the turret. I'll see if I can find my old Hardinge book. Or you can do what I did, just rip everything out that says Fanuc on it, and upgrade to modern controls. I can now reset the turret with a mouse click.

[drdos]

Because you have absolute encoder on the turret motor, we can change the zero position fairly easily. The servo which is driving this has a parameter that you can change and reset your home position. Rotate the turret until tool one is at the # 1 position. In MDI mode and PWE (Parameter Write Enable) on you can toggle parameter 0022 bit #3 xxxx0xxx. DOT NOT CHANGE THE VAULES OF x’s. So if parameter 0022 looks like 00001011, the type in 00000011, this will alarm out requiring to cycle power. Cycle power and release EMG. Now change parameter 0022 back to its original values 00001011. Assuming that the 4th axis is the turret.

[Jim Dawson]

If what drdos does not work, here are the turret reset instructions from the Hardinge OT manual


''1.1 Ensure that the turret is at a safe location
2.1 Press Reset, Press Estop
3.1 Release Estop, Press Estop Reset
4.1 Press & Hold Zero Return button, Press Turret Index

Note: turret should index to station 1''

Best of luck

[VincePlasma05]

Thank you drdos and Jim Dawson. I've tried both options this morning, I've tried Jim's turret reset instructions first with no success - maybe the machine builder (Takang) had a different reset sequence.

With drdos method I was able to find the parameters in the manual as well, the bit values were not correct as per the manual on the controller, looked like they were changed/wiped to 00000000. One of the bit's is defining an absolute or incremental encoder. I changed it to absolute. I followed drdos instructions, but the no success.

Unfortunately, I'm still stuck with the same problem. Once I select any tool, it indexes and moves to a tool position that is 2 positions higher or lower than the selected tool position. I'm able to take photos of the ladder and post them here if that might help ?

Bit numbers increasing from right to left :

Parameter 0021, bit#2 0: Incremental pulse coder is used for 3rd axis
Parameter 0021, bit#2 1: Absolute pulse coder is used for 3rd axis

When equipping absolute pulse coder :
Parameter 0021, bit#6 0: There is no coordinate running without axes motion at initial power-up
Parameter 0021, bit#6 1: There is coordinate running without axes motion at initial power-up

Not sure what bit#6 does ?

Parameter 0022, bit#2 0:Reference point of absolute pulse coder for for 3rd axis is not fixed
Parameter 0022, bit#2 1:Reference point of absolute pulse coder for for 3rd axis is fixed.

I'm assuming the turret is seen as the 3rd axis on the Fanuc 0T ?

Thank you guys for all your help thus far.

[Jim Dawson]

Sorry that didn't work. Any further comment by me on the OT controller would be pure speculation.

The only other things I can suggest is to check the turret home and in-position switches/prox for proper operation, and if equipped with a turret drive belt, make sure it's not slipping.

[VincePlasma05]

Hi Jim,

Thank you very much for your help - I appreciate it. It's a strange fault that we have - I've tried a few combinations, but still no success. The Duplomatic turret does not have a drive belt, but rather a 3 phase motor with an internal brake, also 2 proximity switches : one for the indexing solenoid and one for the absolute encoder as a locking switch when it locks into a tool position.

Unfortunately there is no home switch for the turret, which would have been great. I'll add a photo of the diagram from Duplomatic. The strangest thing is that when I initially select a tool on the operators panel's tool selector, for example, tool #1 and press the tool start/index button, the turret rotates and locks into position. But when I look at the diagnostic screen the encoder's value is that of tool position 3 or 11 (12 station tool turret), depending on which way the turret rotated, clockwise or counter-clockwise. If I then change the tool selector switch on the operator panel, to tool #2, the solenoid does not unlock and the turret won't rotate. If I then select Tool #3 after Tool#2, the solenoid unlocks and the diagnostic screen shows that the encoder's value is the same as the tool selector switch's value. This happens before I push the index button. This sequence of 2 tool positions out of sync, happens for every tool number on the tool selector. If I select Tool#5 the encoder's value is that of Tool#3 or 7 (depending on rotation direction again).

Everything else on the machine works perfectly - it would be a big shame if I can't get it fixed. I've taken a look into Centroid's DIY retrofit kits, if I can't get this fixed - this may be an option, any suggestions Jim ?

Thank you for your time.

[VincePlasma05]

Here is a few photos of the Duplomatic's data sheet regarding the Cycle procedure and the internals of the turret :



- - - Updated - - -

[Jim Dawson]

It sounds like your controller is really confused. This problem is similar to what we had with our turret, and quite frankly is what prompted us to rip out the Fanuc controls. We did get back into sync by starting a tool change so the turret unlocked then hitting E-stop and power off and rotating the turret with a 2x4. By that time we've had enough of a 30 year old Fanuc controller. I don't know if this would work on your system. I don't exactly know how ours worked, but it did have a servo motor driving it.

I wrote my own controller software, but Centroid and DMM Technologies servos would be a good choice for your application. The only thing left in my lathe that says Fanuc on it is the spindle motor. Everything else was replaced. I used four DMM 1.8KW servos, to replace the original Fanuc servos. X, Z, Live tooling, and Turret. I'm very happy with the result, the machine holds +/- 0.0002 all day long. I'm going to add another 1.8KW DMM servo to drive the C axis so I can take full advantage of the live tooling for mill turn applications. This is a whole project in itself.

I do have to say that a lathe is a lot more complex than a mill to do a controls upgrade on, a lot more going on. It took me about 10 hours to do the upgrade on my mill, but more like 3 weeks to do the lathe, but part of that was software debug time.

EDIT: After looking at the drawing and the operating description, the one thing that hasn't been mentioned is the encoder. It could have a problem.

[Chrisptm]

Please don’t laugh but does the turret have a centre plate with the position numbers on it
If so has the turret had maintenance
On a Miyano it’s possible to put the turret centre plate back in the wrong place ( indicated number on the turret centre plate to tool position on turret )
So no matter what ever number you call up it will always be wrong regarding the tool number
On the centre plate
Sorry if this sounds rubbish but sometimes this crazy **** happens

[drdos]

If parameter 21 are all 0’s then you do NOT have absolute encoders. So my procedure won’t work in your case. (Leave them all zeros) I believe the D0460 area holds the key. As you rotate the turret one of these D-numbers must have a value of where the turret thinks it is. You might be able to change one of them to reflect where it really is on the screen. MDI mode and PWE on.

[VincePlasma05]

@ Chrisptm - thank you for the advice. Haha sorry for laughing, but that was one of the first things that we checked.

Unfortunately the diagnostic screen on Fanuc 0T indicates that there is a difference between the selected tool number and the encoder's actual position value. The encoder's position value, which should correspond (when indexing has finished) to the tool selectors value, are different values.

For example, what should happen is, let's say when Tool 1 is selected on the operators panel, the diagnostic setting (first 4 bits) for the tool selector should change to 0001, which it does. The problem comes when you press the Tool Start Index button, the turret rotates, the value of the encoder's diagnostic setting changes as it rotates, but the tool turret locks into a tool position Tool 3 or Tool 11 depending on rotation direction, 2 tools from the selected tool, which was Tool 1. Now the encoder's diagnostic setting value is 0011 (thinking it's Tool 3) instead of the selected Tool 1's value of 0001. The funny thing is, it's always 2 tools out of sync.. The machine is a used machine that we bought at auction, I have no history to go on unfortunately. I have seen indications of tampering/attempted repairs by the previous owners - I don't want to think to what extent they tried to do repairs on the machine... they did etch over the old number plates, new tool numbers - but they are irrelevant. The diagnostic screen holds the key. Thanks again.

@ drdos - I agree with you that we might be able to change one of the diagnostic settings - I will give it a try today and post any success. I've double checked the manufacturers data sheet, it definitely is an absolute encoder (they refer to it as a Angular Position Transmitter (Absolute)) - I hope the previous owners/operators didn't change any of the parameters/diagnostic settings for whatever reason.

* Can the tool turret be the 3rd axis that the parameter manual mentions - if so, how can I display the axis letter on the Position page to see if there is any movement, there should be a parameter to view the axis on the CRT ?

* Is there any way that someone could see on the ladder which parameters/diagnostic settings are being used for the turret's operation and the stored/current tool position value, that would give an indication to why the turret is moving to 2 tools out of sync ?

Thank you guys for the ongoing help - I appreciate it - I'll post again if there is any change in the turret's behavior.

[Jim Dawson]

Another thought just occurred to me. Is it possible to rotate the encoder shaft relative to the turret drive to bring it back into sync?

[machinehop5]

[B] The funny thing is, it's always 2 tools out of sync.. The machine is a used machine that we bought at auction, I have no history to go on

...totally a wild guess here. does the Fanuc control have a parameter for the Number of Tools the Duplomat has? sounds like the Fanuc thinks it has 14 stations .

DJ

[Edwin Murch]

Can someone give me the X axis AC motor number can't read mine !
Does anybody got one for sale ? I do have DC motors for CHNC II If needed .
CHNC I
wiring diagram A13B-0139-8540
GEF OTB
CN-3085-T