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IndustryArena Forum > MetalWorking Machines > Okuma > Okuma VMC Model MB56VBR
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  1. #1
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    Dec 2006
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    270

    Okuma VMC Model MB56VBR

    Dear Experts
    Hope you are all fine and safe
    We are facing tool unclamp issue, please fine below our actions and observations for your advice


    1. Toll does not get unclamped for full stroke hence unclamp input does not get ON but if we apply emergency & switch ON control after releasing Emergency then only for the first time, unclamp works perfectly alright for full stroke but later on unclamp stops almost at same place again and again - this observation is repeatative
    2. Hydraulic oil level and condition good
    3. Replaced valve with another machine - no effect
    4. Replaced complete set of Motor, Hydraulic oil tank and Solenoid valve with another running machine - no effect
    5. One more observation is that collet does get connected with drawbar with little difficulty unlike other machines
    6. Added 1.5mm spacer to improve knock out but to no avail
    7. Motor is getting heated up that means getting overloaded


    Please advice if return line of oil is getting clogged somewhere & thereby not allowing unclamp for full stroke, if yes, how do we move ahead because we have opened
    concerned pipe and checked for any clogging etc did not find anything

    Based on the above, request your feedback to ascertain reason due to which every time if we apply emergency & switch ON control after releasing Emergency then only for the first time, unclamp works perfectly alright for full stroke but later on unclamp stops almost at same place again and again - do u also suspect drawbar movement getting obstructed somewhere?

    Regards

  2. #2
    Member
    Join Date
    Aug 2009
    Posts
    525

    Re: Okuma VMC Model MB56VBR

    ...if your machine uses Belleville washers on the drawbar...possibly some may be broken
    https://en.wikipedia.org/wiki/Belleville_washer
    https://www.cnczone.com/forums/showt...0CNC%20Drawbar

    Check your parts manual maybe,
    DJ

  3. #3
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    Dec 2006
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    270

    Re: Okuma VMC Model MB56VBR

    Thanks for your response. Coiled springs (1 set = 2 numbers) being used not Belleville washers in this machine, we had checked and found both of them to be ok in terms of Spring force as checked manually by hand and also grease etc

    Now trying to check and operate cylinder externally to find out in case of any internal leakage - not very sure although

  4. #4
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    Dec 2006
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    270

    Re: Okuma VMC Model MB56VBR

    Dear Experts
    Pl refer to previous thread regarding tool unclamp issue
    1. Tool unclamp cylinder checked externally with air pressure found ok
    2. As u r aware, there are two spacers on drawbar in line with coiled springs, we found width of both spacers to be more vis a vis one more drawbar in stock
    3. Replaced new drawbar
    4. As u r aware, there is an input called "unclamp cylinder retract confirm" which should be ON during clamp - somehow we have doubt that, this input was malfunctioning & thereby unclamp stroke was getting interrupted - please revert if that is possible, because we did not find much of abnormality in the entire assembly of course except width of spacer
    5. Please let us know on how to check ladder for output for tool unclamp to see of this can get interrupted due to input called "unclamp cylinder retract confirm"

    At the moment machine is ok but under observation
    Thank you so much for all your support of members of this forum
    Regards

  5. #5
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    Join Date
    Apr 2009
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    1043

    Re: Okuma VMC Model MB56VBR

    In your maintenance manual there should be logic diagrams for the tool changer that show the sequence of events and the inputs that need to be made in each case. Before an alarm occurs, you have 3 minutes that you can look at the DIAGNOSIS page to see what the error is or what it is looking for. Based on your description, you may need a slight adjustment in either your draw bar stroke or in your proximity switch. Your not so local rep may be able to give you some pointers on Draw bar adjustments or have a procedure they can send you. It sounds like yo have already thoroughly cleaned the entire mechanism?
    Experience is what you get just after you needed it.

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