Re: Belt Cleaner "Chattering"
Hi Shane,
Cleaner chattering is normally caused by improper tensioning of the cleaner; by material build-up on the cleaner; by uneven sticky build-up on the belt itself; or by isolated uneveness in the belt cover.
To investigate, it is necessary to watch the cleaner in operation. Hopefully, the observer can catch when the cleaner starts to chatter and when it is stable. Once this is known, it is possible to isolate the cause.
To respond to your possible causes:
Although different cover hardnesses can cause differences in cleaner action (you get a higher drag effect with softer compounds), this is normally not a problem if the cleaner tension is sufficient. Also, the durometer difference from belt section to belt section should not be great (I'm assuming that all belt segments are from the same supplier and are the same specification).
The splice thickness should be the same as the rest of the belt. Therefore, this should not create a problem for the cleaner. If there is a difference in thickness, you can buff the surface of the belt-splice area interfaces to provide a gentle lead-in and exit for the cleaners.
As far as repair methods are concerned, this sounds like a perfect application for Eli-Flex, Rema T2, or no action. The choice depends on the severity of the cover damage. Even if you decide not to conduct spot repairs, you should buff off any damaged cover that is higher than the surrounding cover surface - this will prevent flaps from being pulled by the cleaners and prevent material from being trapped.
Regards, ■
Re: Belt Cleaner "Chattering"
Dear Mr. Shane,
It is difficult to give specific comment without knowing types of cleaners, material being handled, etc. because there are various types of cleaners.
If you are referring to the belt damage, then please check your primary cleaner which happens to be the first at discharge pulley. The positioning of this cleaning blade is tricky. It will have minimum dig-in affect when encountering the obstacle (projection on the belt), if it’s cleaning tip and pivot is right angle to the belt or if it is parallel to the belt. You cannot position it at right angle, so only position is nearly parallel to belt. Please check its angle with the belt motion. If you reduce the angle there is less dig-in and chattering for this particular cleaner.
Now a days widely spoken secondary cleaner’s cleaning tip and pivot is at right angles to belt. Please check whether it is so. If it is making acute angle with the velocity of belt, then it will tend to chatter.
Also, check the cleaning pressure. As per your assessment, you have belt damage due to cleaners, so this could be also due to higher pressure. Analyze the possibility of reducing the pressure. Somewhat less cleaning is easy to manage compared to belt damage.
Finally, you need to discuss the matter with the supplier of your belt cleaners, and what they say is final.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
Advisor / Consultant for Bulk Material Handling System & Issues.
Email : parimul@pn2.vsnl.net.in
Tel.: 0091 (0)20 25882916 ■
Re: Belt Cleaner "Chattering"
Shane - I have noticed that some types of lagging can cause belt cleaners to chatter. Primarily this is caused by the weld-on types of lagging when the strips of lagging are welded directly to the pulley surface. Any type of lagging can cause this if the strips are not butted together properly. These can be spaced so far apart that the belt will sag slightly into this gap resulting in an uneven surface for the cleaner to navigate resulting in the chatter. Make sure that the manufacturers recomendations are followed when installing lagging. ■
Re: Belt Cleaner "Chattering"
Shane
In my experince, belt cleaner chatter can sometimes be caused by the slip-stick phenmonena. When the frequency of the slip-stick phenomena gets close to the natural frequency of the belt cleaners, chatter occurs. The frequency is affected by a huge number of parameters such as distance of belt between rollers, presence of water, cover compound, belt stiffness, belt weight and the price of tea in China.
Two remedies I've successfuly used in the past are to install a pressure roller or, in the case where the belt cleaner itself was being excited, to stiffen the belt cleaner arrangement so that the harmonic is pushed beyond the range of the slip-stick.
I would take a good look at it while running and try to work out which element (cleaner or belt) is getting harmonically excited and try to change the natural harmonic of that element. ■
Re: Belt Cleaner "Chattering"
Thanks for your responses
I am a still a little lost as to why it would occur on 2 of the splices and 2 random sections of belt and not the entire belt
I think Matt may be on the right track - how do I tell if it is the belt or the cleaner being excited
For further info
They are 3 PROK p-types all in the secondary position
The cleaners appear to be adjusted fine,
There is a fair bit of material builup on the carry strand troughing frames that are in contact with the return side belt ■
Re: Belt Cleaner "Chattering"
If your belt cleaner itself is being excited it will be dancing around while the belt is only being moved by the cleaner. Vice versa for belt excitation.
The splices may be chattering because the belt is heavier or stiffer in this particular area. ■
Belt Cleaner "Chattering"
Dear all,
If a spiral rubber cleaning return roller is provided next to the Belt Cleaner, than also the belt may jump over the cleaner blades, causing the "chattering".
Regards ■
Re: Belt Cleaner "Chattering"
Hi Shane
We have seen this problem from time to time, and Matt Crokers thoughts are as close to an answer you can get from this. The other thought is the type of P type cleaner you are using. There are many copies of the original Belle Banne product, including the Prok version, however from experience many of the Prok copies have bent poles and rely on a rotary, torsion adjuster. As was mentioned earlier in this dialogue, these secondary cleaners must have tip and belt contact of 90 degrees. This then cannot be achieed long term with a rotary adjustment.
If you are after secondary cleaners with rotary adjustment, you cannor go past the U type.
If you want more detailed advice, please fell free to message me directly. You should be able to get my email address from this page somewhere. ■
Re: Belt Cleaner "Chattering"
M Meyers makes a good point. The U-type will have a very different vibration profile to the P-type copies you have and is very likely to eliminate this problem. Given that you have 3 P-types, it is possible that you might need the extra "grunt" of the U-type anyway.
Talk to the supplier about the arrangement before throwing one in. You need to get the pressure roller arrangment etc right. ■
Re: Belt Cleaner "Chattering"
Hi Shane,
I would check the adjustment angle again. Chattering usually occurs when the cleaner blade is presented at a backward angle to the running direction of the belt. The chattering can be caused by the slip-stick condition that Matt has described and also by the vibration of the belt during operation. Readjusting the blade so that it has a forward tilt (up to 5 deg. from the perpendicular) normally eliminates the problem. However, if the belt is reversible, then the angle should be set to zero. Also check on the alignment of the blade to ensure it is correctly bedded. Easiest way to do this is to shine a flashlight at the contact area and look for gaps from the other end.
On the belt repairs, I agree with Dave that you should buff off any uneveness. If too much of the covers have been taken off, then you should consider using repair patches with reinforced fabric to make up for any loss of lateral strength always ensuring that the repaired area is even or slightly lower than the surrounding cover.
Hope this has help.
Barry ■
Belt Cleaner "chattering"
I have a Steel Cord belt which has had damage occur to the carry cover because of the belt cleaners chattering/vibrating.
I am unsure what has caused the cleaners to chatter.
The configuration is 3 P - Type cleaners at the head end all after the tangent point on the pulley
Is it possible that any of the following can cause this?
- difference in duro of covers
- Thickness of splices, it has occurred on 2 of the splices, but also on 3 random sections for 4 to 5 metres
They are high speed cushions on the cleaners
The belt is a Steel Cord inclined belt that runs at 4.5 metres a sec.
Also any thought on repair methods - I can buff them out but this leaves the cover very close to the cord plane
I am thinking about not touching them - any thoughts?
Thanks
Shane ■