TCP precision trouble, fanuc welding robot

  • Hello everyone, I'm new to the forum.


    I'm working with two fanuc robot for welding task. Model 120ic and controler R-30ia. The TCP was never great on either one, it move around at least 5mm. It wasn't a problem since we could weld pretty straight anyway. They have runned like that for at least 5 years.


    But now we need to have them certified by the Canadian Welding Bureau. The certification process include to "configurate and adjust the TCP".


    I didn't find any method to define the tool that worked, so we figured out it must be the Masering. We tried to redo it, but we got two problem; we don't find the align mark on the 5th and 6th axis and I don't think using that method alone is precise enough? Surely there is a more precise way to do it no?


    So to resume;


    1: Anybody has certified fanuc robot with CWB?


    2: Where are the mark on the 5th and 6th axis?


    3: Are there any method more precise than to align the mark?


    Oh and before I forget; english isn't my first language and 95% of my knowledge is self-learned. Although I explored these robot far and wide for five years, I know I can be considered a rookie and I'm more than happy to learn new/real technique/procedure.

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  • I'll look for that, meanwhile is there a way to adjust the 5th and 6th axis without it? I'm not sure we can get the jig in time. The test is 16 march.


    For the 5th I tried to rotate both the 4th and 6th axis by 180, I belive the tip of tge tool should stay at the same place?

  • That stands to reason, and good thinking.

    I tried it, it worked great. I also made something similar with the 4th and 6th axis.


    For the 4th, I put robot it that position:


    J1:0

    J2:30

    J3:-75

    J4:90

    J5:-90

    J6:0


    I mesured from a fixed part of the tool to a centered machined part at the base of the robot. Rotated J4 by 180° until both mesure were the same.


    For the 6th I put the robot in that position:


    J1:0

    J2:45

    J3:0

    J4:180

    J5:-90

    J6:90


    Then again I mesured from a fixed part of the tool to a centered machined part between the 3rd and 4th axis. Rotated J6 by 180° until both mesure were the same.


    One robot went from +/- 8mm to +/-4mm and the other from +/-5mm to +/-2mm


    The difference is barely visible when looking at the mark. I'm currently working on a similar process for the 3 first joint, but I'm not sure I will find something.

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