Re: Impact Beds & Impact Idlers
Shane:
Why are impact beds in vogue? They can provide two essential services for some installations:
1. Minimize transverse or width-wise rubber stress between steel cords during large lump impacts. Lack of tranverse suport allows large local deflections from high impact. This is sometimes controlled by a transverse fabric.
2. Sealing of skirtboard by not allowing belt dilation between idlers that create gaps that material and fugitive dust can escape, and can allow material to become trapped under the skirt thereby degrading skirt and gouging belt cover.
They also can create excessive belt cover wear, impact bar wear, associated maintenance, drag and heat which exacerbates wear.
Attempts have been made to produce a happy medium between the two by having skirts sealed with longitudinal wear bars only under the skirt rubber and impact bars between idlers. Idlers keep the belt just above the impact bars minimizing drag and abrasion, and only become of value when there is heavy impact belt deflection.
I am sure others have points of importance yet to be said.
Lawrence Nordell
Conveyor Dynamics, Inc.
www.conveyor-dynamics.com ■
Re: Impact Beds & Impact Idlers
I agree with Larry.
It is a mix between load support/impact and skirt sealing.
Load bars running along the skirt line and fully setup to under the belt at this point is best to reduce skirt spillage.
If the belt is weaving/mistracking at the load zone, U can peel off the outer rubber discs on impact idlers.
Load beds are better where the belt is short and U have a screw take up - where the belt tension is not guaranteed to prevent excessive sag.
If U see star type damage to your belt, esp. in the middle, then U know that U have an impact issue on your belt and need to consider doing something.
Cheers
James ■
Re: Impact Beds & Impact Idlers
Hello Mr. Shane,
Impact table will have certain advantages on particular points in certain type of applications. Impact idlers have its own area of application where the same will be optimum.
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: Impact Beds & Impact Idlers
There is a misconception about belt support systems I would like to clarify. It is not a matter of one or the other when it comes to impact idlers and impact beds. It is a matter of selecting the right solution for the application.
There are several choices when it comes to belt support systems in the loading zone of the conveyor belt. Two goals should be met, protecting the belt and preventing spillage as much as possible. The choices available are standard idlers, impact idlers, impact beds, and seal support cradles. The best technology is usually a combination of the above.
The selected equipment is based on the maximum lump size of the conveyed material, the homogenius flow of the conveyed material, and the length of drop of both. A recent Cema standard has been introduced to help clarify this (CEMA 575-2000)
As stated previously, belt support systems perfom two functions, protecting the belt from impact damage, and preventing entrapment point damage to the belt due to belt sag under the sealing area due to deflection.
The best impact bed design will prevent belt sag in the outer sealing area, and is actually below the belt line in the center loaded area of the impact zone. This must be designed into the impact bed. The impact bed should also contain a slick top cover to minimize belt drag, and an absorbing layer to reduce impact damage.
Impact beds should always be installed in conjunction supporting idlers before, between, and after the inpact beds.
When loads are lighter, a simpler seal support system can be used to prevent belt sag in the load zones. Again these are assisted with standard idlers.
For further explanation of belt supports systems please refer to Foundations III, chapter 6, page 60 by Martin Engineering. ■
Go Dynamic
Hi Shane,
Coming in a bit late on this one but my thoughs as below:
The ultimate solution to load zone impact damage is to go dynamic.
For a heavy duty solution you should check out Leverlink Dynamic Impact Beds.
Utilizing innovative low maintenance torsion spring technology in the design these beds help dissipated the kinetic energy imparted onto the belt by the product. They also have the added advantage of dampening vibration to the main support structure.
Leverlink Dynamic Impact Beds are designed application specific and are modular in that they consist of a number of units end to end to cover the load zone. Being modular means that they work individually as well as collectively in the load zone. It’s a bit like having a Sherman Tank suspension system working upside down. On a tank every drive track wheel has independent suspension and modulates with the terrain. Likewise the Leverlink Dynamic Impact Bed modulates with the changes in the load zone, each module as an individual unit can react quicker to changes in its area of the load zone and work together collectively to fully support the belt.
The simple equation to longer belt life is energy transfer, with static beds a lot of energy is being transferred through the belt and into the bed and support structure. The Leverlink design does not reduce the amount of energy transfer, it can’t change the laws of physics. Instead it understands them and works with them by absorbing and dissipating the energy transfer. The Leverlink unit bears the brunt of the load and cushions the impact to the belt resulting in extended life and reduced costs.
As for spillage, that's a seperate problem that well designed side skirts, edge support and load deflectors can help with.
See this site and links for more info.
www.forceintech.com
Follow the link for Leverlink Dynamic Impact Beds.
Regards
Tony Watermann ■
Re: Impact Beds & Impact Idlers
impact beds have a few benefits but need to be set up correctly and with some careful consideration in the following aspects:
inter-spaced idlers:
for higher speed belts it is generally necessary that the belt remains clear of the slide surface in the unloaded condition.
The belt contact to the slider bar should only be occasional - if the product flow is steady state continuous the friction and pressure may generate a lot of heat, damaging the under side covers and the slider bars.
the belt tension & belt mass:
a lot of work that is considered to be done by the impact bed is actually done by the belt tension and the belt mass. The belt mass inertia opposes the impact force; similarly - the belt tension (particularly with high tension belts) requires that the particle energy is dissipate to deflect the belt.
Ideally, the impact bed will just cope with instantaeous (extreme) impacts from lump products ■
Re: Impact Beds & Impact Idlers
Impact beds are a total waste of time in my opinion.
They dramatically increase impact damage to the belt, and I have replaced too many to count, with proper loading arrangements.
They are like toy spanners...fantastic until you try and use them.
I would not buy an impact bed even if Meg Ryan had slept in it!
Cheers
LSL Tekpro ■
Meg Should Keep Better Company
If Meg knew you where going to try and sleep over just to impact her bed, the boy anti-spanner would become her weapon of choice.
Shame on you for suggesting such drivel. I can say that properly designed impact beds provide great relief, comfort and long life.
Properly designed impact beds do not offend the belt. Quite the contrary, they protect its complexion, giving a bright and cheerful appearance.
The moral of this opinion, don't believe in fantastic stories of use and abuse due from some engineers at the expense of others with more impeccable skills.
I will let Meg know you are carousing her neiborhood.
Viva la tinto ■
Re: Impact Beds & Impact Idlers
Dear Larry..
I am very glad that once again you whole-heartedly agree with me.
Cheers
LSL Tekpro ■
Impact Beds & Impact Idlers
I am curious to people's opinions on impact beds & impact idlers.
What are the advatages and disadvantages with each. To me impact beds present too hard a surface under the belt.
Aren't impact beds a bit like placing a hard board under a belt, if you try to hit a nail through a belt it would go through a lot easier with a hard surface underneath.
My feelings are that it increases the likelihood of impact damage.
I'd love to know of other peoples thoughts and experiences with both.
Shane ■