Fanuc Robodrill

[Wolfenstien]

Good evening all,

I wondered if any of you had experience with a fanuc robodrill. I bought one last year that had been partially retrofitted to Centroid. It has a centroid oak in it and DMM servos.

The spindle a direct drive servo motor and was replaced as part of the build. I really haven't used it much, but it appears to be a functional 3 axis machine at this point.

One thing that wasn't completed as part of the retrofit was the tool changer. The owner didn't know how to integrate the existing tool changer mechanism. I'm told that for a short time he installed 4th servo and used it to move the carousel as an attempt to regain and ATC. When I had purchased it he had removed the carousel and been hand loading tools.

I'm really not well versed on how the drill tap machines work, but my understanding is as follows.

There is a guide track on the side of the Z azis and a cam roller is located in this guide track.
The ATC carousel sits at an angle holding the tools away from the z azis.
When the Z axis moves up to the tool change position the cam roller moves up along the guide track and which has an angled section built into it. At the appropriate height that this track swings the ATC into line with the spindle. The drawbar disengages as the same time to the ATC arms encapsulate the tool.
The Z axis continues upwards leaving the tool in the ATC and the spindle up out of the way.
There is a metal gear that is part of the spindle assembly that sticks proud of the spindle casting in the front. When the spindle is at top of travel this gear meshes with a gear on the ATC. Tool changes occur by the spindle rotating. Each rotation of the spindle spins the ATC at the ratio of the spindle gear to ATC gear. Presumably 1 rotation of the spindle equals 1 tool position movement. (Must be some even multiple because the drive tangs have clock requirements.).

My understanding is that there are two things missing.
1) As of right now when in the tool change position there is no logic that causes the spindle to rotate causing a tool change.
2) There is no logic telling the control what tool is in position.

I've not seen an example of this type of tool changer. PLC As far as I can tell its 100% mechanical and has no prox sensors to determine tool location. Would you essentially need to tell the control which spindle was in the spindle each time you powered up? And from there it would rely on accurate spindle indexing to track tool number?

Does anyone have an example of a tool changer PLC program that works in a similar fashion?

I'll see if I can upload some photos when I get home. That might help solidify the concept for some folks. I've found surprisingly few posts online on how these tool changers work and how to repair them. (First task for me is to re-install the tool changer).

TIA

[cncsnw]

So it sounds like you need a spindle motor that is capable of servo-like positioning, so that it can rotate exactly the right amount to index the carousel from one tool to another.

What kind of drive and motor do you currently have running the spindle? You said that the original spindle servo had been replaced, but I did not see where you said what it has been replaced with.

Keeping track of the last-known carousel position, and using that as the basis for the move to the next tool, is not especially difficult. It just takes some attention to the programming details, to ensure that the variable(s) that track carousel position always, and only, get updated when the carousel moves. There also needs to be some type of operator-controlled error recovery procedure, for when a stall or fault occurs while the carousel is in transit (leading to a loss of position).

[cncsnw]

From your description, is sounds conceptually very similar to the Emco VMC described here:
viewtopic.php?f=64&t=6015

[Wolfenstien]

So it sounds like you need a spindle motor that is capable of servo-like positioning, so that it can rotate exactly the right amount to index the carousel from one tool to another.

What kind of drive and motor do you currently have running the spindle? You said that the original spindle servo had been replaced, but I did not see where you said what it has been replaced with.

Keeping track of the last-known carousel position, and using that as the basis for the move to the next tool, is not especially difficult. It just takes some attention to the programming details, to ensure that the variable(s) that track carousel position always, and only, get updated when the carousel moves. There also needs to be some type of operator-controlled error recovery procedure, for when a stall or fault occurs while the carousel is in transit (leading to a loss of position).

Thanks for the response Marc. I believe you are exactly correct in that I believe the original fanuc spindle did achieve atc control by servolike control of the spindle. Whether you call that a C axis etc. But yes I believe this will only work if the new spindle motor also has this ability.

Regarding what is on the machine now my understanding is that its supposed to be a drop in knock off of the original. (Doesn't mean thats actually what it is however its a chinese version of the original japanese motor).

The attached photo is the part numbers from the prior owners order from when he bought the replacement motor.

This link takes you to the website of the new motor specifically the 3.7 kw version of this motor which is what was ordered. My specific motor was speced to provide up to 12K rpm max which is over what is speced as the standard (8K). Just reading through the description this unit is supposedly capable of C axis like positioning.

https://www.szghauto.com/product/115.html (Motor)

https://www.szghauto.com/product/96.html (Drive)

The seller said he can send me data sheets and the manuals sometime this coming week. I've also reached out to the manufactuerer directly to see if I can get the most recent manuals.

So can this new motor and drive do the necessary positional control. (Maybe.....)

[Wolfenstien]

This is the manual for the motor/drive combo I have.

http://www.automationtechnologiesinc.co ... oad/21040/



Same spindle setup different website. Specs are the same so presumably different face for same company.

https://www.automationtechnologiesinc.c ... xygMemNOvB

[Wolfenstien]

Turns out the engineering group at SZGH is readily accessible through whatsapp.

Looks like these spindle drives are controllable through step/dir input. The engineer I was able to reach explained which wires accept the +/- pulse and +/- dir inputs as well as the parameters to change to run in pulse/dir mode.

I assume I would ultimately configure this as an additional axis and not just as a VFD with +/-10v control?

[Wolfenstien]

I've been chatting back and forth with the engineer which has been pretty handy. It appears there is an input L4 on the drive that will switch the drive high speed mode to position mode. So I believe I can basically use the spindle as both a high speed machine spindle as well as a positional controlled servo by turning that input on and off.

Going to take a little doing as I'm slightly out of my depth, but at least sounds plausible.

[cncsnw]

I was about to ask that question, so it is good you have already found out that you can make the drive switch modes (between pulse-train position mode and analog velocity mode) on the fly, in response to a digital input.

That would be part of the battle. The other part would be figuring out how to get the Centroid Mill software to deal with an axis that comes and goes: that sometimes is available for positioning, and other times will just spin for no reason apparent to the motion controller. The Lathe software has such support, for a C axis. I don't know of a comparable feature in the Mill software.

It would almost seem like you could just remove power from the axis servo (e.g. with "M93/C"), and that then CNC12 would not care that it was spinning away while the PLC ran the drive as a spindle. Unfortunately, CNC12 currently re-enables all axes at the start of every job, and possibly in some additional circumstances. Trying to run the drive as a spindle while CNC12 thinks it is enabled will result in a "410 ... position error". Nonetheless, that might be an avenue to pursue, if you can get some help from Centroid.

The way Oscar solved his Emco VMC was to program the spindle drive with a series of positioning profiles, managed by the drive, and commanded with a set of digital inputs. E.g. multiple inputs would select one of "move minus 4 places", "move minus 3 places", ..., "move plus three places", then another input would send the "start" signal, and the drive would turn the motor the requisite number of turns. That allowed the carousel positioning to be commanded entirely from the PLC.

If your drive has enough digital inputs, and has the ability to store and perform positioning moves of various distances, then you might be able to use that solution as well.

[Wolfenstien]

That would be part of the battle. The other part would be figuring out how to get the Centroid Mill software to deal with an axis that comes and goes: that sometimes is available for positioning, and other times will just spin for no reason apparent to the motion controller. The Lathe software has such support, for a C axis. I don't know of a comparable feature in the Mill software.

It would almost seem like you could just remove power from the axis servo (e.g. with "M93/C"), and that then CNC12 would not care that it was spinning away while the PLC ran the drive as a spindle. Unfortunately, CNC12 currently re-enables all axes at the start of every job, and possibly in some additional circumstances. Trying to run the drive as a spindle while CNC12 thinks it is enabled will result in a "410 ... position error". Nonetheless, that might be an avenue to pursue, if you can get some help from Centroid.

cnckeith,

Can you address Marks comments above regarding the ability of the mill software to utilize a single servo for both high speed spindle work and C axis work within the mill profile? If not a current function is this something that could get added into an upcoming update?

[Wolfenstien]

Engineering responded to my question regarding internal positioning profiles which are available on some drives. In this case it appears no there isn't an option for that. They do allow up to 4 "home" positions so you can clock the spindle in up to 4 discrete positions, but there doesn't appear to be a motion profile you can save. I did watch a youtube video on a KEB drive that allowed up to 34 discrete programmable options which must be similar to the delta drive you mention from the EMCO thread. A neat option I'd not heard of before, but not a solution for my spindle motor/drive combo.

Hoping the Centroid team can comment on Mark's remarks above regarding the possibility of switching back and forth between a high speed spindle and a positional axis in the milling software.