sizing a motor 2

[SR71-110]

Hi All,
I have to size a motor for a rotary device (a drum). The drum has a normal force applied to it. What would be the best way to size a motor for such a system?

Thank you.

 

[dvd]

Evaluate all of the various torque needs -

acceleration torque - what is the mass moment of inertia of the system and how fast does the system need to get up to steady-state speed?

operating torque - how far off of normal is the force application, will this create a torque need? How is the force applied to the drum - with a roller? What sort of interface forces are created tangentially? Deformation torque - will the applied force deform the drum? Bearing frictional torque, including seals. Misalignment torque.

 

[Gr8blu]

Second what dvd mentioned. Look at the torque required to operate the device in a steady-state (or at least minimally transient) condition. Then look at the acceleration time/torque requirement. Then look at whether the application requires constant or variable speed - and how does the required load torque change with that speed?

Constant torque applications will (usually) require a somewhat higher nameplate power rating compared to variable torque designs to provide sufficient mass to handle the thermal issues inherent to the operation.

Converting energy to motion for more than half a century

 

[SR71-110]

Hi,
I tried finding the torque for the motor, just want to make sure if this makes sense.

The wheel is being pushed to the drum with a force, the drum is 3-4 times bigger in diameter compared to the wheel.

I did T= F*perpendicular distance.

I am using the radius of the drum, because the wheel is pushing on the drum, does this make sense.

 

[MintJulep]

In another post you linked to this video:

https://www.youtube.com/watch?v=Iuya2buTQKE

As dvd correctly stated, Evaluate all of the various torque needs.

Here are the torque needs:

 

[dvd]

The attached may help or it may sidetrack you.