Arrow1000 Z Axis grid failure


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Thread: Arrow1000 Z Axis grid failure

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    Default Arrow1000 Z Axis grid failure

    We have an Arrow1000 with A2100 control and kollmorgan drives/ motors; at startup we have a z axis grid failure when trying to home the machine. All axes move after powered up; all register movement on the display screen. When homing, we get the z- axis grid failure. We checked the TPA and Limit switch on z through programware and visually, all ok. Checked continuity on wiring from the drive to the A2100 board, all ok. Slowed the feedrate down as suggested on other posts, no help. Any ideas?

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    I've given detailed descriptions of how the align sequence works before so won't retype it here, but not enough information from you to give you a solid answer.

    If it was the align switch failing, it would normally keep moving until it overtravels (direction depends on whether signal failed open or closed).

    What does (or doesn't) the axis do? Have you recently changed anything (like the motor or coupling)? Have you changed the hard drive or has anyone modified settings? Does the machine have the optional scale feedback on the Z-axis?

    If you've changed anything on the axis recently, could just need a longer seek move.

    If scale feedback, likely in the scale or reader head, but have seen the cables fail too.

    If the hard drive was changed, several settings can cause an align failure if they are not correct.



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    Default Re: Arrow1000 Z Axis grid failure

    Ok, sorry for the lack of info.

    No scale feedback, all motor

    Z axis TPA switches on and off when looking at it in programware; when it tries to align, it hits the switch 3 times before getting the fault.

    The axis will jog up and down as normal after powering it up. When I go to align the machine, Z moves up and hits the TPA switch, lowers a little, moves back up to the switch, then lowers more than before, goes up, hits it and stops with the fault.

    Have not changed anything on the machine. I do have a spare hard drive and put that in to see what happens, same thing; switched it back. No settings changed except for a small toolchanger position adjustment a few weeks ago. We had a power outage last week while it was on; no part running at the time, but ready to run. This happened after that outage; we got this fault once, they reset it and it ran parts. I come back after shift to run it that night and the fault won't clear. I did get a note that any tool they set with the tool probe that day were set lower. I checked all the parameters for the tool probe and they are the same as usual.



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    Default Re: Arrow1000 Z Axis grid failure

    it does look like the fault appears slightly before the switch makes up



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    Default Re: Arrow1000 Z Axis grid failure

    Quote Originally Posted by kccrusher View Post
    No settings changed except for a small toolchanger position adjustment a few weeks ago. I did get a note that any tool they set with the tool probe that day were set lower. I checked all the parameters for the tool probe and they are the same as usual.
    I think you should be looking into why the Probing is lower now. The TC position has changed something sounds like.

    DJ



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    Quote Originally Posted by machinehop5 View Post
    I think you should be looking into why the Probing is lower now. The TC position has changed something sounds like.

    DJ
    It’s just the tool probe, the part probe functions normally. The tool probe set tools correctly until after the z axis grid failure. All parameters on the tool probe page are the same as they always have been. I don’t think that the tool change position changes anything pertaining to the tool probe. I believe the change in height was around .150”.

    I checked the condition of the ballscrew and it “looks” fine. I tried to move the complete z to see if a bad bearing or ??? Prying up with a 6’ 2x4 produced nothing. I would assume that would lift it unless I underestimate the weight of the spindle. We had a bad annular bearing on another machine’s x axis and it would miss alignment at times until we changed it out.



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    Default Re: Arrow1000 Z Axis grid failure

    The fact that it moves to the switch, then off and back towards it indicates the switch is opening and closing. However, these switches are prone to sticking over time, which alters the timing of the alignment and your comment about "then lowers more than before" makes it sound like this is a possibility. This is why the sequence doesn't just look for the switch and align when it sees it, it hits the switch, moves off and back to confirm the position before completing the alignment. If everything is set up correctly, you shouldn't be able to "jump a grid" and align in the wrong position which sounds like may have happened since your position appeared to have changed. Unfortunately, as these machines get older I see many of them with settings that have been tweaked or hard drives from other machines installed so aligning in the wrong position becomes possible. I'd start by physically examining the switch (not just looking in PWare) and see if the plunger feels like it is sticking at all. Even if it seems OK, I've seen the contacts take longer to open/close so isn't a guarantee the switch isn't causing the failures.

    As you mentioned, bad bearings can cause alignment issues, but with the Z-axis, gravity keeps the axis down, so you won't really see the effects of backlash during the alignment. If the bearings are bad enough to have allowed the axis to drop a significant amount (they would need to be extremely bad for this though), it could cause an alignment failures or an alignment on the next grid. A more likely possibility would be a damaged coupling. I don't know what type of couplings were used on your machine (they changed with different models/years), but have seen all types fail so it is worth checking the coupling to see if it is damaged.

    Another possibility is if the align switch or dog are loose and are out of position, could cause issues during alignment as well (although your description doesn't sound like this is the case).

    The only other thing that comes to mind because you mentioned it started after a power outage is the possibility the encoder/resolver in the motor was damaged so the reference pulse isn't there (or the wiring for the reference pulse is bad).



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    Default Re: Arrow1000 Z Axis grid failure

    I checked the bearings, I get about .008" of movement; the movement is in the annular bearings. Coupling looks good, it's the vee groove type. Switches look aligned and those and the dogs are tight. I sprayed WD40 on the plunger and it felt ok, but it's in a tight spot; will check it again. The switch is an easy change, might try that, as it is the original switch.

    Is the reference pulse separate from the signal the control gets to keep track of the axis movement? I did not check continuity of the wiring from the encoder to the BDS4, as we had thought it was ok, as it had movement and kept the position reading on the display.



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    Default Re: Arrow1000 Z Axis grid failure

    maver1ck,

    I went back and pulled the align switch off to give it a good cleaning and check; I did it in place before. It seems to be smooth; put it back on, made sure it was lined up with the dog, powered it up and went through alignment without a problem. Looks like a late night for me to try to plow through some of the backlog.

    thank you for your help, it's appreciated.



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Arrow1000 Z Axis grid failure

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Arrow1000 Z Axis grid failure