project help power screw calculations

eamonhonda

or my project i have to design a cardboard box compressor without using hydraulics etc. So i am using a power screw method. Two power screws with a motor a worm and spur gears. The only figures I am given for the project are that this thing must output 5000kg of compressed material an hour. Does anyone have any idea what kinda calculations i have to do so i know what size motor etc i need to get and what sizes i need to design everything at.
edit: power screw is same as lead screw if im confusing anyone

Turbulent Bill

Check out 'Shigley's Mechanical Engineering Design' by Budynas and Nisbett, it has a good section on lead screw design and use, torque for applied loads etc.

The project description is pretty vague, so I'd get the typical density of cardboard and work out the required volume for 5000kg (plus a bit extra as the compression isn't perfect). Size your compressor to this and the number of cycles per hour you'd expect.

eamonhonda

Turbulent Bill wrote: »

Check out 'Shigley's Mechanical Engineering Design' by Budynas and Nisbett, it has a good section on lead screw design and use, torque for applied loads etc.

The project description is pretty vague, so I'd get the typical density of cardboard and work out the required volume for 5000kg (plus a bit extra as the compression isn't perfect). Size your compressor to this and the number of cycles per hour you'd expect.

ya this is what i was thinking alright. Its the 'bit extra' and a few other things that have me stuck. I have the shigleys book it is a help

eamonhonda

any idea how i could work out a value for the 'bit extra'

FarmerGreen

30%, no make it 40. 5 metric tonnes an hour?
Of air. Its gonna be a biggy isnt it.
Made out of cardboard.
Its getting complicated now.
The lead screw thing is Kind of counter intuitive, because it going to leak like a sieve.
The Chinese make a nice set of bellows with square boxes and chicken feathers as a labyrinth seal. . . . .
How can I put this, say you have cylinder of compressed gas and you open the tap a bit.
Theres a hissing noise, but it doesnt all instantly leap out.
I think its a speed of sound thing, the same reason that gas turbine engines are so huge,
gas wont go through a hole quicker than mach 1.
Thats the seals sorted, now the cardboard thing.
No make it 900%.
We need a bit more of a project definition chico.
One solution would be to leave a big stack of boxes in a field and let the wind blow through them.
But its not April 1st yet.
Tell me exactly what you want it to do (and dont change it), how much will it cost, how much time do we have.
Its really not worth starting until you've nailed the problems nuts to the table.
Then the fun starts! Thats the scarey part.
Next.

Turbulent Bill

eamonhonda wrote: »

any idea how i could work out a value for the 'bit extra'

It depends on how the boxes are received, e.g., fully-assembled or partially broken up. Obviously the volume of raw material you have to handle will vary hugely based on this, and therefore the size of the compressor.

I'm guessing this is a school/college project, so ask whoever set the project for clarification. From my own experience these projects often have deliberately vague constraints to get students thinking and asking questions, the same thing you find in industry.

Turbulent Bill

FarmerGreen wrote: »

30%, no make it 40. 5 metric tonnes an hour?
Of air. Its gonna be a biggy isnt it.
Made out of cardboard.
Its getting complicated now.
The lead screw thing is Kind of counter intuitive, because it going to leak like a sieve.
The Chinese make a nice set of bellows with square boxes and chicken feathers as a labyrinth seal. . . . .
How can I put this, say you have cylinder of compressed gas and you open the tap a bit.
Theres a hissing noise, but it doesnt all instantly leap out.
I think its a speed of sound thing, the same reason that gas turbine engines are so huge,
gas wont go through a hole quicker than mach 1.
Thats the seals sorted, now the cardboard thing.
No make it 900%.
We need a bit more of a project definition chico.
One solution would be to leave a big stack of boxes in a field and let the wind blow through them.
But its not April 1st yet.
Tell me exactly what you want it to do (and dont change it), how much will it cost, how much time do we have.
Its really not worth starting until you've nailed the problems nuts to the table.
Then the fun starts! Thats the scarey part.
Next.