Tool changer quit working

[acrodave]

I have a Mighty Comet with a 520AM control ......

The toolchanger suddenly quit working, and all it does is to retract the Z axis to 0.0000, and then it stops ........ same thing in a program, or in MDI ...... No error message ....... it indicates that the operation is running, but nothing is happening......

I seem to remember the same thing happening once before, and I was able to get it working, but I'll be darned if I remember what I did to get it going...

Any Ideas out there??

Thanks

Dave

[girishdk]

Hi,

Is it stopping at Zaxis 1st Ref. or 2nd Ref.?

If 2nd Ref., then some machines have a Limit Switch to interlock the Z-axis 2nd Ref. position, so this limit switch may not be working.

Some machines also have a Position Switch (s/w CAM) as interlock for this position, if 2nd ref par. value is changed, it is also required to change in this PSW.

Regards,

Girish

[acrodave]

I'm not, exactly, sure what you mean by 1sr ref, and 2nd ref, but I suspect you might be referring to the z position where the tool changer is aligned with the tool flange (1st ref), and the position where the tool changer is above the pull stud on the tool (2nd ref). If this is the case, it moves to the 1st ref spot, and stops.

The 1st ref spot above is where the machine zero is established on this machine. , and I do not believe there are any real travel limit switches on the machine.

IF there IS another switch, which stops the machine at the 2nd ref above, I suppose it's possible that switch is stuck, although I would think that would result in the tool changer crashing.....

This has got to be something pretty simple...... but what it is has evaded me.

Thanks for your input

Dave

[acrodave]

OOps ..... I re-read my reply, and got the description of what I think is 2nd ref wrong..... corrected here



I'm not, exactly, sure what you mean by 1st ref, and 2nd ref, but I suspect you might be referring to the z position where the tool changer is aligned with the tool flange (1st ref), and the position where the Z AXIS is above the pull stud on the tool (2nd ref). If this is the case, it moves to the 1st ref spot, and stops.

The 1st ref spot above is where the machine zero is established on this machine. , and I do not believe there are any real travel limit switches on the machine.

IF there IS another switch, which stops the machine at the 2nd ref above, I suppose it's possible that switch is stuck, although I would think that would result in the tool changer crashing.....

This has got to be something pretty simple...... but what it is has evaded me.

Thanks for your input

Dave

[onthebumper]

What kind of tool changer do you have on this machine, umbrella style, magazine...? If it is a magazine, does the magazine rotate when you call a T command? Does the spindle orient when Z goes home? Can you orient the spindle manually?

Tool change issues are tough to trouble shoot and often times require digging into the PLC to see where it is getting stuck.

Look in your manual for the machine and see if there are individual M-codes for stepping through a tool change. This will make things a little easier to see if certain moves can be done individually.

[acrodave]

It's an umbrella type tool changer, and the spindle does not orient ......

Hmmn ...... Perhaps the real problem is just that ...... if the spindle doesn't orient, the thing would just sit there waiting for that to happen.....

I'll look at that..

Thanks

Dave

[acrodave]

Well, I got it working......

I first tried to, manually turn the spindle when the tool change process stopped, thinking that, perhaps it would show me if the spindle orient was the problem ...... nothing ...... but I did notice the spindle turned really easily ..... obviously it was in neutral.

Then, for reasons I can't even say, I tried to run the spindle ...... it happened that I picked 800 rpm, which is in low range ....... I heard the "clunk" of the gearbox, and the spindle ran ...... then I tried the tool change, and, voila, it worked ....... Hmmmmn

Then I tried running the spindle at 1000 rpm (high range for the gearbox), it ran, and the tool changer worked ..... Hmmmmn

The machine worked fine for the rest of the day...... I figured it was something intermittent. Remember that I had said that this happened once before, but I couldn't remember how I fixed it.....

Sitting here at home, it has just dawned on me what I think is causing this problem ........ When this machine shuts down, the spindle transmission shifts into neutral. It doesn't shift into high, or low range until it a speed is commanded. I was trying to do a tool change, right after I turned the machine on, without having run the spindle ....... therefore, the spindle was in neutral, and thus would not orient, which stopped the tool change process!!!

That is the theory ...... I'll do some experimenting tomorrow to see if it proves to be the case.....

Ain't CNC machines fun!!!!

Thanks to those who tried to help...... the question asked of me about whether the spindle was orienting, by On the bumper, was the spark it took to send me on the right path..... sometimes just being able to "think aloud", and hear other peoples ideas and questions can be invaluable...

Dave

[acrodave]

My suspicions were correct ...... it won't do a tool change unless the spindle has been issued an "S" command. Some experimentation shows that it is not necessary to start the spindle, but simply issuing an "S" command puts the spindle in gear, so that it will orient, and then continue with the tool change.

This is wierd, and, obviously, it isn't too often that I have tried to change a tool, immediately after turning the machine on, and zeroing it with a G28 XYZ.

Hopefully, my experience will help someone else who gets into this situation....

Thanks to those who helped with their comments.

Dave