[nixwake2snow]

This has been an ongoing issue we have been having. Very frequently when the turret rotates and clamps we get this alarm. And basically the only way to really get rid of it is to change one of the parameters for the turret clamp position angle. Have to change the degree by .05 all the way to 1.5 sometimes. This works for maybe 10-15 tool changes and then have to adjust it again. Does anyone have any ideas on where to start looking. If it is just a limit switch adjustment for turret clamp, or if it is the encoder, or something in control. Thanks

[fordav11]

the fact that it rotates means the servo etc is ok. as each tool is called the turret angle parameter will re-set itself so setting it manually doesn't do much to solve the problem.
on my machine inside the front turret housing there's a limit switch and a pin with an angle on one end that runs up and down and touches the limit switch. the pin is sprung and touches the turret as it rotates. they can get sticky with coolant and oil. we had similar errors and we pulled it apart and cleaned and adjusted the pin/switch stroke and the problem hasn't come back. my machine is not an LB but yours may be similar in build. If you have the parts book take a look for the break-down of the parts.

[underthetire]

The fact that the only thing that clears it is changing angle parameters leads me to believe something is going on with the curvit (sp?) coupling. Either debris build up, or inner coupling bolts broken.

[nixwake2snow]

I checked the clamp/unclamp switch. On my machine i have 2 proximity switches for it. Actually was fairly clean underneath the cover. Also the switches and trip dogs were clean to. Rotated the turret numerous times and it seemed to clamp and unclamp just fine. I did notice that after it rotates, when it is clamping the turret will rotate a little either CW or CCW, depending on the tool pocket. I checked and tools 1-4 all rotate a little CCW, tool 5 CW, tool 6 and 7 CCW, tool 8 CW, tool 9 didn't rotate at all, tool 10 CW, tool 11 didn't rotate at all, tool 12 CW. Now that I am thinking about it I think these could all be so different because the turret clamp position parameter is different for each pocket. I'm not sure if getting all the tools to clamp without rotating would help or if something is going on like what underthetire said with the curvik coupling, or bolts broke. In a way I am leaning that way. Any thoughts let me know if I should pull the turret off. Thanks again for your input.

[cncts11]

I see that slight rotation all the time...exactly as you described...it is almost always caused by a tool imbalance. Let's say you have heavy tools in pockets 1, 2, and 3; normal tools in pockets 4-9 and nothing in 10-12 (this is extreme, but just to explain my point). When tools 1-3 are coming up towards the top and you clamp while they are moving up, the weight of these tools will cause the turret to be slightly behind, so when it clamps, the curvic coupling pulls it up a bit as the bevel surfaces mate together. When tools 1-3 are either at the top or bottom, the weight doesn't affect the rotation, so the turret clamps pretty straight. When those same tools are going down, it causes the turret to rotate ahead a bit (aided by gravity), so when it clamps, the curvic coupling pulls the turret back a bit as the bevel surfaces mate. If you want, you can check the turret rotational speed as it rotates around, just hold the index button and watch the turret speed (check data), you will notice it actually speed up and slow down depending on where the position of the heavy tools are while it is rotating. Now, it is possible that you aren't that unbalanced, but if you have wear in the drive components, that will amplify the situation. If you take all the tools out, you will notice that it probably rotates and clamps pretty evenly all the time. Balance the tool weight as evenly as possible, that will help; however, you probably already have some wear so if it eventually becomes too much, you will need to replace the worn components.

[fordav11]

I don't think unbalancing is an issue with such a large turret and servo drive. if it's not physical wear on the curvic coupling more likely the servo needs to be zero'd out. there's a special procedure to re-calibrate the turret if the servo or encoder has been replaced (or in your case if it gets out of position for some reason).
re-zeroing the servo may help.
otherwise you need to get your hands dirty and pull off the turret and see whats going on there.

[cncts11]

The size of the turret or the servo has nothing to do with it; if you have lost motion in the drive mechanism, you have lost motion - that simple. The zeroing procedure will get you station one. You perform multiple indexings to "teach" the system the other stations (technically, they are calculated, but multiple indexing "fine tunes" the positions). If the zero is off, it almost always results in all the stations being off in the same direction. As long as it isn't off by too much, the bevel surfaces will pull the curvic together. The fact that he is seeing the turret overshoot one way and undershoot the other way signifies that it isn't a unidirectional problem. Setting the zero position is used to re-established station 1 - it has nothing to do with the other stations; those are calculated and established by the system from zero - if he is seeing deviation between stations and can consistently see it happening, you can re-establish the zero until the end of time and it won't fix it. As I said before, check the turret speed while it is rotating continuously (to see if there is any deviation in the rotation with your current tool setup). Then, remove the tools and see if you get the same results (overshoot/undershoot) you saw with your stations when there are no tools on it.

[Algirdas]

re-zeroing, of course - the final accord of turret adjustment. Don't understand, why degradation of part accuracy is not mentioned. Turret is misaligned mechanically in my opinion. The turret center is in distance of indexing center, and maybe more issues also.
Turret needs mechanical alignment, first. Check centers of all tools, draft the sketch and - finally - automatic re-zeroing in case, if alignment is acceptable

[fordav11]

a slight mis-alignment is fine. my machine does that always and I have no alarms. I accept the misalignment simply because it is an Okuma ;-)
exactly how much mis-alignment do you have? if it's more than 1-2mm you need to re-zero the encoder. if that does not help you must inspect the turret mechanical parts for wear/damage.

[nixwake2snow]

Thanks everyone. I will try and take a closer look at how much misalignment I have and may pull the turret off this week sometime. Thanks again and will update when I have more information.

[nixwake2snow]

Sorry it took so long to get back. But I think I figured it out. For some reason there was a .5 in the backlash comp. I changed that to zero. And then went through a turret zero offset procedure and it has been working great for 2 days without any issues. Thanks everyone for you input.