Help on Drive Motor Horsepower

Posted in: , on 9. May. 2010 - 10:53

Hello everyone. I am an electrical engineering student designing an automatic color sorting belt-pulley conveyor system. I found the CEMA resource for determining the needed horsepower found here: http://cemanet.org/beltbook/BB5thEdChapter%206.pdf

I went through the calculations and I would very much appreciate someone to look over my result to offer some verification before I purchase my drive motor. Here are my calculations following directly from the reference above:

http://img406.imageshack.us/img406/3...orhpsizing.jpg

(you may need to right-click and save image in order to zoom in to a viewable size)

It is also attached to this message.

The belt I plan to use for the Wb value is here:

http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT

And the Idlers I plan to use for the Ai value is here:

http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT

Thank you very much for any assistance you may offer!

Attachments

drive_motor_hp_sizing (JPG)

Re: Help On Drive Motor Horsepower

Posted on 9. May. 2010 - 03:23

If nobody wishes to look at my calculations and see if they seem reasonable, I would still appreciate it if you could please answer this simple question:

Does 0.002 hp seem like a reasonable number for a 2 foot long conveyor belt, conveying one pound items at a rate of 1 pound per 3 seconds? I am pretty unfamiliar with horsepower ratings and would like to know if 0.002 is a ridiculous number or not.

Thanks for either looking over the calculations or for answering my simpler question!

Re: Help On Drive Motor Horsepower

Posted on 9. May. 2010 - 07:11

Those asking for assistance should have patience!

Re: Help On Drive Motor Horsepower

Posted on 9. May. 2010 - 08:47

As a student you need to THINK about what you want to do and seek references applicable to your problem. So think about this -

You have found a formula in a publication

1) is the publication relevant to your application? The CEMA publication basically relates to TROUGHED belt conveyors. Is your belt conveyor troughed or flat?

2) is the formula relevant to your application? Look at example 1 on page 127, the conveyor length is 300 ft, and the capacity is 500 te/hr. Is this anywhere near the length and capacity of your conveyor?

As I read you application, your conveyor is very short and of low capacity so maybe the formula you have found is not actually relevant to your application.

It should, however, point you in the way of calculating YOUR power requirement but you need to work from first principles to establish a suitable method of power calculation NOT slavishly put numbers into a formula from a book.

Just go through the conveyor and note down all the elements that will absorb work as conveyor operates. Then derive calculation methods for them, finally adding them all together to get the answer.

But do not expect to be able to look up all the information you need. Some of it may need to be established experimentally so there will be another challenge for you to design a suitable experiment(s) to get the information you need.

As an engineering student this is part of your training and you will be a better engineer for it

Re: Help On Drive Motor Horsepower

Posted on 10. May. 2010 - 04:18

Try again.

Me thinks the power will be much higher, even though I have no idea of the tonnage rate. Me thinks the material acceleration and skirt drag will dominate.

This will likely be many times the rolling losses over a set of idlers that have no shape.

Lawrence Nordell Conveyor Dynamics, Inc. website, email & phone contacts: www.conveyor-dynamics.com nordell@conveyor-dynamics.com phone: USA 360-671-2200 fax: USA 360-671-8450

Re: Help On Drive Motor Horsepower

Posted on 10. May. 2010 - 04:20

You must also add pulley and scraper drag values.

Lawrence Nordell Conveyor Dynamics, Inc. website, email & phone contacts: www.conveyor-dynamics.com nordell@conveyor-dynamics.com phone: USA 360-671-2200 fax: USA 360-671-8450

Re: Help On Drive Motor Horsepower

Posted on 11. May. 2010 - 07:06

Thanks for the replies.

nordell, the tonnage rate is 0.6 tons/hour.

I'm in the process of trying derive the power needed from a physics problem viewpoint. Although I'm not very good at mechanical physics at all since all my classes focused on electrical aspects.

I may just be reduced to buying a motor and seeing if it works, which is pretty bad.

A motor like this will do it for sure:

http://cgi.ebay.com/Electric-Gear-Mo...item335795e7e6

It's rated for 0.081 hp.