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Thread: Conveyor Belt Degradation

  1. #1
    Join Date
    Aug 03
    Posts
    15

    Belt creasing in idler gaps - carry idlers & v-returns



    Has anyone got experience, information, solutions or suggestions on the problem of belt degredation (excessive local wear, creasing, longitudinal cracking, bend memory, becoming brittle etc.) due to the belt being 'pulled' into the gap between idlers - particularly on 45 degree carry sides and V-return idlers. We have suspended 45 degree idlers on 1800 belts at 4,000 to 6,000 tph. My concern is that we are getting premature belt degredation in that local area of the idler v's, causing belt cracks & holes and requiring replacement of belts when the rest of the belt is fine.
    DECTECAU

  2. Dear Dale Coward,

    From the description of your problem there are only three possibilities which can cause the problem.

    1) The gap between central roller and side roller is more than permitted limit, i.e. link connection is not of proper design / arrangement. I can give you suggestion if you inform about this connection.

    2) Belt is not stiff enough, i.e. belt fabric and thickness are not of adequate lateral stiffness. This you should take care when you are replacing the belt ( as and when arises).

    3) Idlers vertical alignment has too much of misalignment, i.e. consecutive idlers in vertical plane are not at proper level. This results into excessive pressing of belt on central roller where the idler is up relative to neighbouring idlers and it can cause pinching. This may be ocurring at many points along conveyor length.

    Possibly the main reason could be as per serial no. 1 and 2. However serial number 3 needs to be also examines at your end.

    Regards,
    Ishwar G Mulani.
    Author of Book : Engineering Science and Application Design for Belt Conveyor.
    Email : parimul@pn2.vsnl.net.in
    Tel.: 0091 (0)20 5882916

  3. Dale,

    Suggest that you contact Bruce Baker to take a look at your system. He has a wealth of experience with belt related problems such as you dscribed and I believe he lives in your area.

    Bruce can be contacted via e-mail at minesite@mining-services.com.

    The three probabilities that Dr. Mulani suggested are the most likely -- but there are other possibilities. A site visit could solve your problem.

    Best of luck!
    Dave Miller
    ADM Consulting
    10668 Newbury Ave., N.W.,
    Uniontown, Ohio 44685 USA
    Tel: 001 330 265 5881
    FAX: 001 330 494 1704
    E-mail: admconsulting@cs.com

  4. #4
    Lawrence K. Nordell

    Lawrence K. Nordell

    President and CEO

    Conveyor Dynamics Inc. [eDir]

    Conveyor Dynamics Inc.

    Professional Experience 58 Years / 8 Month Lawrence K. Nordell has 58 Years and 8 Month professional experience

    Discussions 2608 Lawrence K. Nordell acceded to 2608 discussions, Articles 0 Lawrence K. Nordell wrote 0 articles, Publications 0 Lawrence K. Nordell Nordell released 0 publications

    Searching nothing specified

    Know-How Design (1521) Lawrence K. Nordell used this tag 1521 times, Pipe Conveyor (238) Lawrence K. Nordell used this tag 238 times, Chutes (119) Lawrence K. Nordell used this tag 119 times

    Dear Mr. Coward,

    Your question and observations suggests an improper design. To the above response I add the following.

    There may be a simple solution to some of the problem causes, or the solution may require a more costly correction depending on the existing design and its fix.

    CDI has experience with belts that can fail due to idler junction stress/strain failure. For long spaced idlers, high trough angles, large widths and tonnage, convex curves, idler transiton zones, existing alignment dimensions, high ore density in combinations with the above, the belt's structural integrity, such as transverse stiffness and worn belt profile, the junction strength may be insufficient to provide infinite or long life at the junction point.

    Belt degradation can occur as you suggest with working the joint area. This can produce many of the characteristics you note from rubber strain work hardening.

    This problem is more pronounced on some equipment such as trippers, stackers, and reclaimers. Here, long belt free spans and deep trough idlers can more frequently work the joint to failure more. In case of these junction conditions, the fix may only require the addition of adding idlers in the junction areas cutting the sharp angle and improvng the belt's support. This type of equipment normally has strucurally stiff belts to overcome this type of problem. However, the belt wears in the center region altering the structural capacity.

    Belt cycle time may increase the failure rate.

    Some load station impact zone designs can cause premature failure.

    We make it a habit to analyze the idler junction for new and worn belts for large and log overlands. We have developed special in-house procedures for this analysis and limiting criteria.

    Giving more information on the belt's construction would allow a more meaningful response such as:

    1. fabric or steel construction (if fabric give details on plies, matl.)
    2. top and bottom cover thickness
    3. strength rating
    4. speed
    5. idler spacing and specified installation accuracy; setttlements
    6. roll diameters
    7. idler transitions and vertical convex curve details
    8. material density
    9. rock size
    10. load impact zone configuration
    11. other apropriate information as suggested from above comments.

    Lawrence Nordell
    Conveyor Dynamics, Inc.
    website: www.conveyor-dynamics.com
    email: nordell@conveyor-dynamics.com

  5. #5
    Lawrence K. Nordell

    Lawrence K. Nordell

    President and CEO

    Conveyor Dynamics Inc. [eDir]

    Conveyor Dynamics Inc.

    Professional Experience 58 Years / 8 Month Lawrence K. Nordell has 58 Years and 8 Month professional experience

    Discussions 2608 Lawrence K. Nordell acceded to 2608 discussions, Articles 0 Lawrence K. Nordell wrote 0 articles, Publications 0 Lawrence K. Nordell Nordell released 0 publications

    Searching nothing specified

    Know-How Design (1521) Lawrence K. Nordell used this tag 1521 times, Pipe Conveyor (238) Lawrence K. Nordell used this tag 238 times, Chutes (119) Lawrence K. Nordell used this tag 119 times

    Another comment:

    The idler roll configuration can contribute to the junction failure as suggested above from an excessive gap and, excessive offset distance between wing and center rolls.

    Some designers have used two rolls Vees on the carry side after the stacker/reclaimer travel limit. The junction force becomes excessive as the belt transitions to the head pulley in some cases.

    This caused a recent belt failure, on a high strength steel cord belt with six years of service.

    LKN

  6. #6
    Join Date
    Jan 01
    Posts
    20

    Avoiding belt degradation

    DIRT WHACKER Solution

    Sirs,

    After reading your post, I allow myself to submit and introduce our DIRT WHACKER Belt scrapers. A belt degradation can be provoqued by a bad cleaning of the belt. Why ? If you have scraping blades with their angle attacking the belt, you damage the belt. If you have scraping blade positionned in the other position/angle, you only push the blade against the belt. This "pushing" effect will leave carry-over between the belt and the blade. Result of this carry-over in between is damaging the belt. That's why we are innovating with our DIRT WHACKER always attacking the belt perpendicularly with a constant angle of 90. No more carry-over as the pressure inflate in the rubber hose is brought by a foot-pump (that we supply). This pressure bring the blades 90 in the belt with a 8-12 kg/cm on the blade which penetrate the belt only 2. Results is a 100% clean belt WITHOUT wearing OR damaging the belt. Another point is due to the fact that if a belt is not cleaned perfectly, you will always have carry over. This carry over will damage the belt, but also the rollers, and all installations.
    ***********************
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    *************************************
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    GERALD COENEN
    General Manager
    Email : info@matam.be
    Fax : 003223530021
    Tel.: 003223546734
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    GERALD COENEN
    Sales Department
    Address
    32, Dreve des Pins
    B-1420 Braine l'Alleud
    Belgium
    Tl.: 00-32-2-354-67-34
    Fax : 00-32-2-353-00-21
    Email : info@matam.be
    Web site : www.matam.be

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