4th axis problems II

[little bubba]

I posted previously about my 4th axis problems a few posts down, it finally was working, then it wasn't, then it was, then it wasn't, anyway, finally found the problem, a badly freyed(sp?) wire in the harness going from the fourth axis.

Now however, we seem to be having another problem, an axis overheat problem. We usually don't shut it down at night, we've found that it won't repeat consistantly on a CS. We used to at least hit the E-stop, but then found that that didn't consistantly repeat(95% good). So now in the morning, flip the monitor on and error #17 on the A axis, overheat condition. Hmmm, shut it down for a few hours (I can only set up so many machines at once). Fire it back up, no probs, except its consistantly showing a following error of 2, all the other axis are at zero. I'm guessing that the non stop following error is causing the overheat, but what could be causing the constant error. This is driving me nuts, we've got a lot of 4th axis jobs coming up in the next weeks, any ideas?

[Al_The_Man]

I am not familiar with the Fadal rotary axis, but I know from experience in designing some that many have a clamping device once in position, if the motor is left enabled and there is a following error at the time of clamping, the motor is trying to position but unable to because of the clamp condition and overheating can occur, it is common on these types to disable the motor and re-enable when actuating a move. I am not sure wether yours allows this, but this is could be the reason.
Al.

[alloyspec]

Little Bubba,
I know what yiu are talking about when you say the cold start won't repeat consistantly. We use an SMW indexer and I do not like to machine the same part that I started yesterday because of slight rotational movements on CS. We turn off our machines every night. The following error you are referring to are the numbers to the right of the axis display? If so, that has to do with the loop gain for that axis. I noticed mine stays at 4 all the time it is not moving. The maintenece manuals tell you how to adjust the pots on the boards to adjust that out. We have never tried it, my bosses don't think it is a problem. I have the best luck luck before shut-down using the menu/home position/return for shut down option. A technician told me it using this instead of HO resets the CS pulse at that point each time. I don't know if this is true or not, the manual doesn't say anything about it. I also use A fixture offsets and leave the indexer on ther CS pulse so I don't have to deal with the return to home position question. I feel it is another place for errors to accumulate. In other words I do not use SetA. If you use fixtures a lot allways mill a flat up close to the chuck so you can quickly indicate in your fixture. Good luck, I hope this helps.

Alan

[gaswiz69]

More then likely your overtemp problem is to a bind of some sort within the rotary. Check motor temp when error 17 is active. If motor is hot to the touch, then it is binding either because the fixture is resting against a hard stop, or the brake is being applied while the axis is trying to move. Unplug the air line for the brake and see if after several minutes of stand still if the brake applies. There is a setting in setp on the last page for auto brake. I always set this to no. If it is not a brake issue, put a current probe on your motor lead with no load and write a program to rotate 360 degrees at a feed of 250 to 500. With no load you should see between 2 to 4 amps for the 360 degree rotation.
Hope this helps,

[Neal]

If you move the rotary to a given position and do not apply the brake if you are going to stay at that position for any length of time, the motor will keep servoing to hold the position. This will cause over heating. There is aparamtert in SETP called AUTO BRAKE. If this is answered YES then after 75 seconds of inactivity the brake will be applied automatically.

Neal

[little bubba]

Thanx for the info, at the time this was happening, there were no fixtures on the 4th, swapping from a 3jaw to a collet, so that probably wasn't the problem. We've been e-stopping it at night, and its been repeating, though on occasion in the past it has not. If I apply the brake at night and shut off the compressor, will the brake still stay applied, a 5C lathe I ran would hold tight overnight with no air pressure, I'm wondering if this will happen with the 4th, I guess I could try and find out.

[ctate2000]

The axis will stay locked as long as there is air pressure. I do not remember the m-code that locks the rotary table but when activated it will stop servo from trying to hold position. The servo has no way of knowing the air pressure has dissipated terefore if pressure is lost and brake disengages the servo will remain off. Go to manual mode and enter it before you leave. You may have backlash problem. The FADAL machines are very good but the rotary tables are not the best. You can manually adjust backlash by moving worm closer to gear but you have to remove table disassemble. This may explain the reason it will not repeat. When programming these tables I have found it best to treat them like a conventional machine and remove backlash by moving in same direction to position. Sometimes it necessary to over-rotate and come back to desired position.

[little bubba]

I've tried applying the brake, but I'm still showing a following error. By not repeating, I mean the machine itself, the 4th is fine, nice and tight. By e-stopping at night, we've only had one overheat on the A-axis in 4 months, and on the last couple of coldstarts, the machine has repeated. The only problem with the E-stop is that I've had the Z move up to .010 over night, though that might have something to do with being right next to the railroad tracks.

Is there a parameter in there that will turn off the servo on the A when I hit the brake, because it definitely is not turning off.

[Neal]

Little Bubba--
When the brake is applied the axis inhibit circuit should cut the power to the rotary motor. Two possible scenarios here. One is that the machine is an older vintage before the inhibit circuit came to be or that the inhibit is not working.

Neal

[DareBee]

Either my machine does not have an inhibter or it does not work.
I know that in parameters I don't have the option of autobrake.
How do I check for sure and what would it take to add an inhibiter.

[dango]

email me your email and I will send you the
drawing for doing that
than when you will make M60 it will
inhibit the amplifier
please send me the type of machine cause there is two
type of amplifier
you can olso purches by Fadal a card that doing the same thing
my email dango2@walla.co.il