chain drive calculation

[SolidCreative]

I’m trying to calculate sprockets for a chain drive powering a belt transfer conveyor.

Things I known are:

Motor RPM 1800
Gearbox reducer ratio 1:8
Conveyor belt linear speed 100 ft/min
Conveyor belt drive pulley dia 7 inch
Horsepower (assumed) 10

One of the two sprockets will be bolted directly onto the conveyor belt drive pulley, which will drive the belt. The other sprocket will be mounted on the end of the gearbox shaft.

Is this enough information for me to make a selection for what sprocket sizes to select?

Thanks for any information you may be able to provide me

Matthew

 

[macmet]

Well you have your gearbox speed. Your conveyor sprocket diameter and speed... Sounds like you have enough to piece it together.

 

[SolidCreative]

so the conveyor sprocket diameter equals the conveyor belt drum pulley dia?

 

[macmet]

You might actually have too many fixed variables.

You know your gearbox sprocket rpms and you know your conveyor output speed (which needs to be converted to rpm). You need to use the ratio of those rpms for your sprocket sizing.

 

[dvd]

It looks to me like you ought to have a higher ratio on your gearbox. Your drive sprocket on the gearbox ought to have at least 15 teeth. If I were designing the drive I wouldn't want the driven sprocket to have a larger diameter than the conveyor pulley. You can get the horsepower charts for chain/sprocket combinations from somebody like Martin:

http://www.martinsprocket.com/2001/SecE.pdf

You might get a more reliable and maintenance free drive using Gates PolyChain belt and sprockets. Note that belt tension with a polychain drive will be higher and you need to size components accordingly.

 

[macmet]

I agree with DVD on the gearbox ratio. We would never use a ratio that low, although I'm not sure your application or why you picked it.

 

[Ross0684]

Matthew
Gearbox output speed =1800/8=225 rpm

Pulley rpm =speed/ pulley circumference
=100/(7/12 x3.14159)
=54 rpm

Sprocket ratio= 225/54=4.166:1

If you decide on say 15 tooth motor sprocket,
pulley sprocket =15 X 4.166= 63 tooth

If as you said required HP =10, sprockets will be substantial size in relationship to your pulley diameter.

Without knowing what the application is, my gut feel is that a 7" dia pulley is not large enough to handle a design requiring 10 HP, or that the motor is oversized for this task?

Ross

 

[chicopee]

Hold on Ross)0684--You are on the right track however, the belt drive head diameter will greater than the drive sprocket dia. of 7".

 

[PeterCharles]

I'm concerned that a power of 10 hp was "assumed".
Was there any basis for this assumption?

Surely a calculated estimate of the required power can be made.

 

[Ross0684]

Chicopee
No offence-
the question does specify pulley dia=7"
and
PeterCharles
I was hoping Matthew would come back with more info so we could possibly steer him in the right direction.
Ross

 

[ID2008]

Can anybody please tell me which software is best to download in calculating chain tension and slack of the chain? Is there a rule of thumbs regarding maximum the chain will slack over time?

 

[tygerdawg]

It appears to me you do not have sufficient info to properly spec these components. You did not state the anticipated loading of the belt conveyor. Startup, stopping, transient, and steady state loading are all part of this analysis. You must account for the dynamics of all translating & rotating elements.

Load analysis will determine Peak Torque applied to the conveyor shaft.

Torque is proportional to HP, so this determines HP.

Torque, HP, and output shaft speed determine the initial gearmotor specs. Your installation requirements and operating requirements determine the shape & size of the gearmotor.

Once you have Torque, HP, and speed, then this determines size & quantity of chains to handle the power transimission from gearmotor to conveyor shaft. Keep in mind that chains typically require periodic lubrication.

I certainly would not "assume" 10 HP without doing the calculations.

Many chain vendors and gearmotor vendors have Engineering Calculation Sections in their free catalogs that will guide you through this.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[TenPenny]

For belt drives and chain drives, if you want to use commercially available items, I suggest trying

http://www.emerson-ept.com

You can register, then use the 'product selection' pages, it will give you several selections, and relative prices for the various options.

I use it frequently for belt drive selections.