How to Calculate Roller Pitch for Chain Driven Live Roller Conveyors
Chain driven live roller conveyors are used to move the products such as carton boxes, plastic crates, totes etc at a controlled speeds higher or lower whatever it may be.
Chain driven live roller conveyors are beneficial because there is positive engagement between chain and chain teeth and gives excellent power transmission for heavy duty loads also.
It is often a complaint that chain driven roller conveyors have more noise. But the noise comes from improper engagement of chain and sprocket. This results because of mis-calculations of roller pitch.
So lets understand it.
Most of us have done chain tensioning to the cycle in their childhood.
We do it, when the chain gets removed from the sprocket frequently, or their is chain noise.
When you adjust the chain tensioning of the bicycle chain, you are actually managing the distance between the chain teeth, so that it engages properly. We do that by reducing the distance between two sprockets or by increasing the distance between two sprockets. This needs to be done periodically because the bolts gets loosened or chain elongates after long working.
Now lets get to some basics.
Any chain have pitch. If a chain is 4" chain, it means that when a sprocket moves by 1 teeth, the chain will move by 4".
By the way 4" = 4inch = 4x25.4 = 101.6mm
Below are the sprocket pitches which are generally used for conveyor rollers.
3/8" = 3/8 inch = 3/8 x 25.4 = 9.52mm
1/2" = 1/2 inch = 1/2 x 25.4 = 12.7mm
5/8" = 5/8 inch = 5/8 x 25.4 = 15.87mm
For Roller Conveyors, chain is transferred from one roller to other. So there is no scope for tensioning as it will disturb other pair. So how we do that.
The Best way is to maintain the optimum distance while design only and there is no need to tensioning.
Lets consider an example. You have to carry a carton box of 400mm length, width 350mm and weight 50kg.
For any product to be stable, there has to be 4 rollers below the product any time. So 400mm / 4nos = 100mm. The pitch should be 100mm.
Considering pitch 100mm, the load on each roller will be 50kg / 4nos = 12.5kg
The load capacity of each roller should be 12.5kg
Check the roller capacity chart.
Here we take roller dia 50.8 which comes with 1/2" x 14z sprocket.
The pitch of roller is 1/2inch i.e. = 12.7mm
Now 12.7 x 8 = 101.6mm
So ideally the pitch should be 101.6mm
If we keep that pitch 101.6mm, it will become difficult to put chain lock and join the chain.
Hence to ease out the efforts, you can reduce the roller pitch and keep as 101.3 or 101
All chains come with Half Lock and full lock. so if we use half lock, we can also use odd pitches. e.g. 12.7 x 7.5 = 95.25mm.
Please refer below video where a conveyor is running at 50meters/min