Help with motor and gearing

[MrRidley]

all,

First off, thanks for reading.

I have a project converting a gravity roller conveyor to a driven one. I have been told that the linear speed is to be 0.3m/min-3.5m/min and that the final drive shiv must be 2.75" in diameter to match the roll. The motor must be 1hp with a vfd.

After some calculations using a 1hp 900rpm motor, I would have to reduce the speed down to 150 rpm with the VFD and reduce it down to 3.76 rpm with a 40:1 gear reducer and then down to 1.367 rpm with pulleys.

For the 3.5m/min which calculates to 15.95 rpm, the motor would have to be sped up to 1754rpm at 116.9Hz, which is almost a 100% increase.

Is there a better way to do this?

Someone please tell me that I am missing something.

Thanks,

Ridley

 

[dvd]

Start with an 1800 (~1750) RPM motor and reduce hertz for slow speed as a first move. I would be a little concerned with the small driven sheave, but if you can find someones belt that will transmit the power, then okay. Call up your local power transmission company ( IBT, Motion, Applied, etc.) and explain what you are trying to do. They will have somebody who understands what you need and will help you in person.

 

[Ross0684]

Hi Mr Ridley
Firstly, you need to advise the means of driving this conveyor.
I assume from your notes that the existing rollers are 2.75", but how do you intend to impose drive to these rollers(Chain, vee belt, timing belt, flat belt etc) as this will then determine the best means.

So far your calculations are correct:

Linear speed of 0.3 m/min= 1.36 RPM

3.5 m/min= 15.9 RPM

Irrespective of your answer, this is an abnormally large ratio change for a VSD motor under normal circumstances.
You would need to consider external fan type cooling for the electric motor when running at the slowest speed(approx 5 Hz).
Ross

 

[MrRidley]

I haven't decided how to link everything up yet. When I said the final drive sheave is to be 2.75", I meant to say that the 2.75" sheave will be on the roll. I don't know if I said that correctly.

Ridley

 

[Jboggs]

1. How will driving that one roll also drive the rest of them?

2. Ask for design help from your local power transimssion distributor. The people that will sell you the motor and drive components can help with the layout and calculations.

 

[MrRidley]

I am bad about leaving out details. We are going to modify the existing rolls to extend the shaft and daisy chain them.