Belt conveyor, twisted type 2

[IMAGINEERGREG]

We manufacture sawmill equipment. I have some conveyor experience but far from extensive. We’ve had a request from a customer to discharge boards from a conveyor by “twisting” the head shaft in relation to the tail shaft. The conveyor is to be 52' long and 24" wide. Speed and live load are yet to be determined but there is the possibility (we’re trying to avoid it) that we may need to run as fast as 900ft/min. At this time I’m assuming <1000lb total live load.. There is no change in elevation.
Apparently this style of belt is used in the lumber industry but none of us here have seen one. This flies in the face of conveyor convention and I’m quite intimidated by the concept.
Can anyone refer me to some resources or links that will help me with the design?

Thank you and regards,
Greg Johnson,

 

[CanuckMiner]

It seems to me that 52 feet is far too short of a flight in which to introduce a horizontal curve (if I understand your "twist" correctly). Horizontal curves are more commonly seen on very long overland conveyor routes.

There are some formulae for horizontal curves in "Belt Conveyors for Bulk Materials" by CEMA

http://www.cemanet.org/

If you don't get any responses here, you may also try posting a question at one of the forums at

http://www.bulk-online.com/index.php

Good Luck and Cheers,
CanuckMiner

 

[jimzpe]

The "twist" sounds to me like a "Belt Turnover" - which leads to a whole list of "huh? and how?" questions if it is. Again, this feature is frequently used on long overland conveyors. Also, as stated by CanuckMiner, not enuf distance (52 feet) to achieve.

 

[mloew]

Are you talking about a mobius strip type conveyor?

Best regards,

Matthew Ian Loew


Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[IMAGINEERGREG]

I have thought I may need to use a Mobius band configuration to make this work. I’m talking about the tail pulley being horizontal, zero degrees, and the head pulley laying at 11 degrees. 36’ of flat bed the twist in the last 18’. Apparently these exist but it’s beginning to feel like an “urban legend” Nobody I know has actually seen one. Did I mention this was our salesman’s idea? (wink)

 

[CanuckMiner]

I agree with jimzpe...it sounds more like an incomplete belt turnover than a horizontal curve as I had originally pictured. Belt turnovers are usually used on the return run to reduce the amount of fines buildup on idlers and pulleys. There are some formulae for determining proper belt turnover geometry contained in Goodyear's Conveyor Handbook. However, trying to achieve this in such a short run sounds iffy.

I do not know your configuration, but a reinforced steel deflector plate/hood may be more practical.

Cheers,
CanuckMiner