Re: Conveyor Take-Up
This has nothing to do with the belt, it is a system design issue but there needs to be a great deal more detail before anyone can help
Cheers
Col Benjamin ■
Like For Like.
As Colin mentioned there needs to be plenty more layout information. The belt supply situation should not affect the take up fluctuations much: always assuming the belts are reasonably identical. We often encounter belt salesmen who state their cheaper belts are absolutely equivalent to European varieties and when it comes down to detail they are lost for words. How 'same' are the specifications?
Looking forward to more detail in the Happy New Year. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
On The One
Dear Mr. Zhu,
in addition to above:
specifically to be checked should be the load cell(s) = force measurement appliances, from device side (response limits, sensitivity) vs. the facual force readouts as input from the conveyor system side.
Pls. forgive my ignorance, but could you explain your meaning at "we use the differ PVG belt from two manufactures but same specification"? This is one conveyor with one endless belt we are talking about? One belt of two pieces from different manufacturers?
Then, "3 drives as tripper", and the location of the winch --> a sketch / drwg is needed. I take it that the winch is inactive during any operational moves --> op. mode description is needed.
However, pls. consider to give more in-detail information from your own considerations about your issue.
Regards
R. ■
Re: Conveyor Take-Up
Hello,
It seems your conveyor is equipped with active automatic winch. The winch unit will be operating as per automation logic and various sensors input going into the automation unit (operation control unit for the winch). Accordingly, winch take-up operation only depends upon the automation logic and the sensors input.
It cannot be influenced by belt of two makes, etc., unless they are influencing the sensors.
Type of operational logic and degree of automation is different issue (these depend upon conveyor design and the designer).
Ishwar G. Mulani
Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 2012)
Author of Book : Belt Feeder Design And Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India.
Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com ■
More Infromation
getlemen:
thanks of your comments and experience.
the belt is from differ manufactures but same specification of PVG 1800S.
the conveyor speed is 4.5m/s, total length of conveyor is 4km, that means the conveyor will take about 30 minutes for one cycle, during one cycle, the winch will be very stable in 20 minutes but alwasy active to adjust the tesnion in another 10 minutes, if it si sensor or laodcell problems, the winch will active always in 30 minutes i think.
we use same control software as last old one conveyor, becase this new one conveyor has same data as old one just be differ of length.
our winch is automatic one and the tension is setting at 55kn(+/-10km), that means if the tension is below 45 or above 65, the winch will response to payout or pull in the carrige in belt storage.
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Request To Consideration / Checks
Dear Mr. Zhu,
thank you for elaborating the information. Pls. check for following:
1) It is the "LOW" limit that makes the winch to respond if the tripper is near head, whereas it is the "HIGH" limit when the tripper is far of the head end?!
2) The factual op time of the winch in relation to belt length also depends from the position of the tripper?!
The factual readout of the loadcell should be seen: Imo (for the extreme positions of the tripper, but perhaps not only there) the measured force should be quite near the limit settings?! Then again i'd like to request you to check the sensitivity of your load cells. Imexp. good devices have an implicit sensitivity deviation of +/- 2 kN, whereas there's appliances with +/- 5 kN and even more. This would, if everything would come out on the bad side, already eat up half of your setting diapason of +/- 10 kN. And (other forum colleagues to comment, pls.) imo to regulate / control your specific system at +/- 5 kN remaining control diapason might be considered difficult.
Remains the point of a belt of uniform properties showing such effect. Pls. comment: The winch is also needed to make up for belt length differing in relation to tripper position. Is there a specific portion of the belt which could be attributed to the issue and if yes does the portion of the belt that causes the issue have any specific properties as a higher number of splices, a splice of lower quality, the related delivery lengths before splicing being manufactured earlier / later / elsewhere o.e.? Does this portion show any effects as mistracking? Does mistracking occur at all? Is there wear on chute sealings attributable to belt mistracking?
I hope you can limit the number of possible influences and finally find the root cause. I wish you best success!
Regards
R.
P.S. I'd be most grateful to learn what you could find out. Thank you in advance for sharing your practical experience. ■
Send For The Red Baron.
By tripper drives I take it you mean booster drives. As shown, material cannot reach the discharge points suggested and if it could the dirty side would be driven.
Can you please indicate what is actually moving during the take up activity and give some dimensions so that the design can be realistically considered? ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
More Information
gentlmen:
i had set up the winch tension as 50kn(+/-15kn), now the system looks fine with load on the belt after the starting peroid. but we have a new problem that during start the conveyor, the belt storage will loosing suddenly even the winch are pulling the take up pulley carriage. we also ignore the tension input from booster compare to last time commission. ■
Pons Asinorum
I cannot understand how material negotiates the booster drive stations and therefore must bow out as a redundant practitioner. Most replies assume that the conveyor shown will allow the material to pass through the first drive pulley before circulating round the underside of the downstream non driven pulley. It didn't happen in my working life so maybe I should pack it in, submit to advanced oriental cunning and concentrate on improving the higher notes of my saxophone. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Pulley Arrangement
i am so sorry that pulley arrangment is wrong and will upload a right one asap. ■
Dear John
Have a Good Year 2014, and please find some time still for the Forum when chasing those high notes. My harmonica is easy compared with a Sax., so the rehearsals must take you quite some time getting the pitch (?). Wish you great success!
Concerning that systems diagram, i took it that regardless of the dimensional relations of that sketch, material can only be transported from somewhere after the two booster drive / wrap pulley arrangements (left side / middle) towards the up head = discharge pulley (right side). But it seems now that that is not correct.
On a lighter note, where does Mr. Richthofen come into this?
Best regards
R. ■
Re: Conveyor Take-Up
Dear Zhu John,
Without doing a re-design for you there is one major mistake you have made and that is to assume that the loop take-up should operate the same once you extend by 2 KM, simply does not happen. You have to completely re-do your design logic as the dynamic stretch of the belt and the need to keep sufficient face tension on the tripper drive so it works as an effective slave to the primary drive are keys. My guess is you need a lot more tension and possibly a bigger loop take-up drive but this is for you to re-analyse
Cheers
Colin Benjamin
Gulf Conveyor Systems Pty Ltd
www.conveyorsystemstechnology.com ■
Fly Past
I thought Baron Von Richthofen might be able to remain seated at the controls while looping around the beltline. Few others would be able.
Happy New Year. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Unstable Control
Your diagram does not include all necessary control functions. The take-up motion is a manifestation of sloppy control. Having drives separated by large distances leaves a question of latency (shockwave response between drives). You need an expert in conveyor dynamics to sort out the problem.
In part, the mid-drive needs a control algorithm which differs from the tail or head. It seems, from your sketch, you are putting a great deal of belt force at the tail. By necessity, this places high tension around 3/4 of the belt loop. The tail drive pulls high tension over the return and half the carry strand. Not good. How does the system know how to accelerate the mid-drive and the tail? Without getting into too much detail, the drives need different logic to control booster and tail as though they were independent. The take-up is responding to an instability someone has designed into your system.
We recently had to modify a carry and return booster drive system logic, implemented by a well known motor and control supplier. The installation is the Essroc Cement operation in Pennsylvania. The work was published by Mr Andrew Jennings, at Conveyor Dynamics, Inc. (CDI), as a SME article. I believe he may also published it in BSH. In any case, it shows some problems in controlling booster drives, which may be of interest in your quest to control instability.
We cannot email copies, since it is SME copyright protected. We can give more detailed references and assist in this area, if the need arises. ■
Conveyor Take-up
Gentlemen:
now we are commissioning a new maingate conveyor with 5KM long and 3 drives as tripper, another 3 drives located at headend, also we installed a automatic winch for take up but the winch adjust the tension frequently during some fixed stage after conveyor running, we use the differ PVG belt from two manufactures but same specification, we just confused why the winch response at the fixed peroid? is that casued by differ belt supplier? ■