Re: Belt Folding Problem
Hi Glenn,
Although it is difficult to give definative answers without viewing the problem as it unfolds (no pun intended), it sounds as if the belt has a momentary contact loss with the take-up pulley. This could cause it to start to fold in its troughed shape. Once this happens, the belt would fold on whichever side happened to make belt-edge contact with the pulley.
Thus, the root causes may be a take-up that has momentarily bottomed out or a take-up that is not reacting quickly enough to changeing tension requirements (i.e. sticking take-up guides). You could confirm this loss of belt contact by placing a video camera and try to view what is actually happening. Or you could expand your take-up travel length, or ensure that the take-up does not jam near the lower part, to ensure that the belt will always be in contact with the take-up pulley.
Other possibilities come to mind, such as wind effects, material build-up, insufficient belt stiffness, et cetera. However, the belt loss of contact with the take-up would be my first guess.
Regards, ■
Re: Belt Folding Problem
Why do you repeatedly need to adjust the counterweight position? Is the TUP travel insufficient for the belt type? As David said, binding of the trolley or bottoming seem to the most likely causes.
However, the root cause may be associated with repeated TUP travel adjustments. This tends to also point to three possible and maybe related problems:
a) lack of compensation of the belt's elastic and permanenet creep travel requirements.
b) trolley adjustment to maintain proper guidance, to eliiminate cribbing
c) can the method of loading the conveyor introduce an exaggerated force that causes excess permanent stretch? You say the belt profile is undulating. Can you momentary load uphill or downhill flights that excced the normal operation and palnned travel?
I would have an expert evaluate the conveyors design for TUP travel compatibility. ■
Folding
Larry, Dave,
This is a problem a customer had in NZ. I have forwarded him this link and he in no doubt enlightened and will contact you if the above cannot solve his problem. I do agree that an expert evaluation is required. (weather in NZ this time of the year is still good and those big browns and rainbows are moving upstream...tempting!) ■
Re: Belt Folding Problem
Glenn,
Could this be Waihi Gold? The original design was extremely strange in the manner of drives for the downhill and uphill.
Downhill had the drives at the head followed by the TUP and the uphill had the drive at the tail. The initial length of the downhill was about 7000 ft from memory.
It was a bugger to get the control system right. It did work.
Another specialist did an upgrade on this system. I do not know any more about it except through publications.
Larry ■
Re: Belt Folding Problem
Dear Mr. Glenn,
Your take-up arrangement mentions that counterweight is acting on four vertical segments of belt. Your information does not clarify whether both the take-up pulleys are on single moving slide frame with counter weight or these take-up pulleys are moving independently with their own sliding frame and counterweights.
I suggest both the take-up pulleys to be on single moving frame attached to single counterweight block. I have seen such arrangement in Malaysia for a yard conveyor and working satisfactorily.
I do not recommend independently moving gravity take-up pulleys for a conveyor.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
Author of Book : Belt Feeder Design and Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Email : parimul@pn2.vsnl.net.in
Tel.: 0091 (0)20 25882916 ■
Belt folding problem
I was wondering if anyone has any ideas on the following:
The conveyor is an overland conveyor system carrying coal. It’s length is approximately 1864m long with a nett fall of 9m over undulating country side typical of the area. The belt tension is applied by a gravity take-up positioned behind the drive head which is a FOX’1500’ series tandem drive head. The counter weight unit consists of a concrete block bolted to a steel pulley frame which travels in a vertical direction in guide rails that are fixed to the transfer tower structure. The return side of the belt is looped through fixed and moving bend pulleys so that the counterweight is suspended by four parts of the belt.
The problem is that on two separate occasions the belt has folded in the counter weight area, once on the North side and once on the South side causing damage to the belt. Although this only seems to happen when the counter weight is very low and can be remedied by lifting the counter weight we feel that we are treating the symptoms and not the cure. It happens very fast for no apparent reason, the belt seems to be tracking ok before hand and there is no obvious explanation. ■