Work table moving with out it being called.

    currently we have one cell that has been causing some issues. for no reason the table begins to rotate either at the operators side or at the welding area.


    equipment

    NX100

    ArcWorld IV-6200M

    HP20 (X4)


    This cell might run for over 6 months without any issues and for no reason it will flip a table when it shouldn't, this happens once and up to three times with in a few days and then goes away for a a few months.


    when the table flips is always after an arc out, shock sensor, collision detect ,weld edit or any other robot stop ( programed or not). S1 has never rotated only S2 and S3 at either side (operator or weld side). when this happens at operators side the safety kicks in and stops it but not after it has move a few degrees, this is our main concern as it might injury an operator. when it flips at the robots well, it rips the torches out of some robots causing major down time.


    Servo card, amplifier, IO card and CPU has been replaced without success. when S1 or 2 moves there is no program calling that rotation, i have paged through the programs and there isn't one calling it. once everything gets homed it runs like nothing had happen.


    we never lose the position of the table, it doesn't cause a minor/major fault and we clear the fault by pressing reset.


    Please let me know any suggestions even if I have already done them, also what you think it might be the problem as it can give me ideas on how to fix it.


    thanks in advance.


    PS. when I say ROTATE it rotates with full speed and full power and if i don't home and master the entire cell and just click restart it will continue to rotate.

    This is a programming issue. The table turning is controlled by the robot. If the instruction to turn the table is executed, the table will turn.


    Seeing is how this is a safety issue, call your local Yaskawa service center to get a service tech to look at it.

    Robodoc

    We have look into that and there is no line in any of the programs that calls for the table to turn (while welding) and if that was the case wouldn't do it every time the robot loads that program? that program is called on every cycle. its like if out of nowhere the cell went into synchronous mode were robot and spanner try to get to one place moving both at the same time. we do not use that function on any of the programs and not even sure if it is enabled. we had it last night and this time we decided to replace the CMOS as we already tried all or most of the hardware. lets see if this takes care of the issue.

    At one point we had Motoman here and he recomended to replace CPU and positioner card, the problem was that it didn't fault when he was here (2 days) and it took several months before it faulted again.

    for the safety we had PLC add extra checks like install a light curtain and disable the robot start unless the roll down curtain is down for the protection of the operators.


    thanks for the reply and i will look again into the programs just to see if i missed something.

    What is the group set of the jobs? R1, R1+S2, R1+S3, S2, S3, etc. Sounds like you are not moving the station while welding or anywhere during the process, correct? Based on the first post it sounds like this only happens after someone has intervened during a cycle. If so, I would check under SETUP, TEACHING CONDITIONS, the setting for BWD OPERATION in NON GROUP jobs. This should be set to PROHIBIT. If set to PERMIT as someone is recovering if they press the BWD key the cursor will move backwards in the master task. This could cause on a restart either a parallel start alarm, if the jobs are PSTARTED, or hardware to start moving.


    Are the station jobs CALLed or are they PSTARTed?


    Generally, towards the top of the master job the positioner will not move unless the robot is inside a cube.

    I know a thing or two, because I’ve seen a thing or two. Don't even ask about a third thing. I won't know it.

    What is the group set of the jobs? R1, R1+S2, R1+S3, S2, S3, etc.



    Group sets are independent meaning that robot 1 is set to one and two to two, this is for the weld jobs.



    Sounds like you are not moving the station while welding or anywhere during the process, correct?


    Yes this is correct S2 or 3 does not move when in auto, only AFTER it has human interaction like weld edit, arc out or any other fault that we take care of. AND yes if set to play start it will continue to rotate the table while robots are welding.


    Based on the first post it sounds like this only happens after someone has intervened during a cycle.


    correct


    If so, I would check under SETUP, TEACHING CONDITIONS, the setting for BWD OPERATION in NON GROUP jobs. This should be set to PROHIBIT. If set to PERMIT as someone is recovering if they press the BWD key the cursor will move backwards in the master task. This could cause on a restart either a parallel start alarm, if the jobs are PSTARTED, or hardware to start moving.


    Its set to prohibit, BUT my twin coordinate is valid. On the first post I didn’t know if that setting was or if it was enabeled on this cell. You think this might be the issue?



    Are the station jobs CALLed or are they PSTARTed?



    We call them and pstart them depending on the situation. If the positioner is sweeping we pstart them so we can have robots go to cleaning and we call them to rotate the station to procede to weld on top.



    Generally, towards the top of the master job the positioner will not move unless the robot is inside a cube.


    This is correct but or positioner (S1) hasn’t move on us only stations 2 and 3 at load side or weld side.

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