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Tip Wear

  • Hi Friends,
    I was facing one issue in Kawasaki robot with spot welding application.
    I made the tip dress program as per Kawasaki standard but when in auto mode robot goes for tip dress and after that it does touch to tip and touch to plate.
    But after this current tip wear for fixed any movable tip is not getting updated properly.


    anyone face this issue please help me.


    Br/Neel

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  • Not too sure what you mean by:

    Quote

    I made the tip dress program as per Kawasaki standard


    - Can you be more specific about 'the Kawasaki Standard' - maybe list settings, program or further details.


    And also:

    Quote

    current tip wear for fixed any movable tip is not getting updated properly.


    - are you saying tip wear for fixed AND moving tip is not updating?


    Are you using Servo Spot weld or pneumatic?

  • Some additional details would be helpful:
    - Like the 'Kawasaki Standard' you mentioned.
    - I would expect also that Obara supply various servo weld guns which would require the parameters entering in the robot controller, so have you done this.
    - I would also expect you to have gone through some force measurements/calibration, have you done this.
    - So details of what procedures did you apply.......may be someone can assist you.

  • Below is the procedure what I followed..
    1. Do the tip dressing - I'm doing tip dressing in such a way that both the tip should cut equally.
    2. Then it goes for touch to Tip - which will equally distribute the tip wear among the the 2 tips.
    3. Then it goes for touch to plate - in touch to plate movable tip only should touch the calibration plate where as fixed tip should be 5~10mm away from the plate.
    4. Then Takes air spot.


    Issue: during point 3 some times wear value goes negative.

  • I think I would be better having a look at a full file save really, can you attach one?
    It could be a variety of things like - zeroing, upper/lower limits setting/clearance values, have you properly disconnected/reconnected the gun and setup the gun parameters correctly (ie the encoder resolution etc)?

  • Nothing really jumps off the page to me.
    I would certainly double check the actual values for your gun setup.
    - resolution.
    - actual distances that the servo gun is travelling.
    - pressure values and posture - wear measurement force
    - speeds.
    - AUX 1029/1030/1031 parameters

  • I think you required this, SGCHIP as command returns the wear vale of the movable as well as fixed tips in mm, u can use this.



    Command is like this: SGCHIP(Gun no.,Movable or Fixed)


    0 is for moving tip 1 is for fixed


    example: tip_wear=SGCHIP(1,0)

    Thanks regards<br />Vipin..

    Edited once, last by vipinpunneri ().

  • Both your K and P force values should be equal for tip closure(K) and touch plate(P).


    The main issues with tip wear come from incorrect parameters for:
    1. Tip base data - tip not properly fitted/compressed before obtaining tip base data.
    - Recommended to always try and make sure tips are fully compressed before - cycle gun at full force etc.


    2. Movement on the plate you reference your tip base data to - make sure it is substantial to withstand the force applied during the measurement.


    3. Resolution values are correct and that when the gun closes with new tips, the axis data for JT7 is as close to 0 as at all possible.
    - The more accurate you set the resolution.....the more accurate the stroke distance will be.


    4. Force Calibration parameters are correct:
    - This will relate to the correct current applied to the motor for the requested force.
    - This is normally done via 1 of 5 postures above/below/yoke up/yoke down/level.
    - Then compensation values would need to be set (as percentage) based on the posture you used to obtain the original force calibration parameters.
    - This will assist in any lateral gravity influences.


    5. Deflection is commonly applied to the spot weld itself - to reduce scuffing - so should not influence tip wear measurement.


    My recommendation is to get a test program together for the K and P process and some tips which include new, known wear dimensions and requires to be executed in Repeat Mode.
    - Start with new tips.
    - Cycle the gun a couple of times to ensure full compression.
    - Place a tick in Aux 1030 - Execute Tip Base Data Change (this will automatically reset to 'No' after completion in Repeat Mode).
    - Carry out your K and P process.
    - Then check Aux 1031 - This is the base data for moving and fixed tip (when carry out further measurement the measured locations is subtracted from these to produce current wear values.
    - Cycle K and P Process for a no. of cycles and view current wear values using monitor screen......current wear values will fluctuate slightly but should be minimal deviation.
    - Then replace either the moving or fixed tip with a known worn one.
    - Carry out the K and P process again for many cycles.....you should see different wear value relative to the to the replaced tip.
    - Swap tip over to other arm of Servo Gun and repeat.
    - If during this the values are substantially different, then I would look at the above calibration values......


    Can be a very tedious exercise, but setting up a servo gun takes some patience and if the calibration/parameters are accurate, then the results should be relatively repeatable......hope this helps....

  • Good day Neel,

    After following these procedures did you manage to resolve this problem? We are encountering exactly the same issue. Please advise.

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