Torque Calculatons During Constant Load

[ddelaiarro]

I have the following set-up:

A brushless motor (w/gearhead) is attached to a pinion. The pinon is mated with a gear (they are normal spur gears). The gear is attached to a shaft with a 20-lb disk (pallet) on top of it that spins at a constant velocity.

The pallet goes through the following cycles:
- accelerates from 0rpm to 30 rpm in 5s
- runs at a speed of 30 rpm for 10min
- decelerates from 30rpm to 0rpm in 5s
- sits idle for 5min
- repeat process 24 hrs/day, 365 days/yr

The uptime on this tool is estimated at 85%. I know the torque that is needed to initiate rotation based on mass moment of interia of the moving parts and drag torques provided by such things as a ferrofluidic feedthrough, water union, etc.

I'm trying to figure out some durability/lifetime information for the gears based on a minimum of a two year life. What I really need to know is the torque required from the motor during the continuous stage (30rpm for 10min). As I mentioned, I know the torque during accel/decel, but the continuous stage is a big tricky.

Any help anyone can lend would be most appreciated.

 

[dimjim]

I assume you can measure the current that
is drawn during the 10 minute cycle to give
you some idea of the torque that is required.

 

[ddelaiarro]

This system is not physical yet, it's still in the developmental stage. I'm working on designing a gear set that will not fail once we've manufactured the system.

 

[dimjim]

Dumb question but can you balance the shaft
by adding a counterwieght opposite the pallet?
Going to be hard on the motor bearings as
designed with that much excentricity.

 

[ddelaiarro]

I'm not sure I understand what you mean? The shaft is in the vertical position with the pallet (a roughly 12" diameter, 2" thick disk) on top of it. The whole assembly looks like a large T.

 

[dimjim]

OK, different story. I assumed a horizontal shaft.

 

[ddelaiarro]

Yeah, I suppose I wasn't very clear on that fact. I forget that people haven't been staring at it as long as I have.