A simple machine for squeezing liqu

[ndems]

A simple machine for squeezing liquid out of cloth has two hollow metal rollers 1 metre long with outside diameter 200 millimetres, inside diameter 160 millimetres (see attached sketch). The top roller is mounted on two spring-loaded 50 millimetre diameter take up bearings on either side. These two bearings run on vertical slides. The bottom roller is mounted on 50 millimetre diameter pillar block bearing on either side on the machine frame. On the top roller drive side is a sprocket 300 millimetre diameter which is driven by a 100 millimetre diameter sprocket on a 50 HP electric motor which has fixed speed of 50 revolutions per minute (RPM). From ground level to top of bottom roller is 1100 metres high. The electric motor is mounted directly under the bottom roller.
Please can you calculate the force generated by the two rollers at 50 RPM and show how you calculate the force. All materials are mild steel. I have got drawing but could not attach this.

 

[3DDave]

If the top roller is spring loaded then the spring load limits the force. It is certainly within the ability of similar setups to pulverize most cloth.

My grandmother had a similar device for washing clothing - a wringer with two rollers. It could squeeze water out and break the bones in a hand if used uncautiously.

 

[ndems]

Hi 3DDave

Please can you show how to calculate the force please.

 

[MedicineEng]

Is this homework?

 

[ndems]

Absolutely not. This is definitely not home work. This was posted almost a month ago. If it was home work then time had already run out.

 

[IRstuff]

Isn't it mostly just the weight of the roller plus the force from any springs in the takeup bearing?

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[FACS]

And the thickness/malleability of the material will determine how much force to compress the springs?

 

[EdStainless]

The rolls are typically jacketed with a fairly hard rubber or urethane so that there is a little more compliance.
The springs are providing 99% of the force, the trick is estimating the contact patch area.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Turn_of_the_Screw]

Agreed that the force vertically on the cloth is just spring and weight. ndems mentions all of the motor specs, though, so maybe they are looking for tension on the cloth. I'm more concerned that the machine is 1100 meters high...

Which forces are you trying to determine and why?

Chris

 

[ndems]

Hi Chris
There's a typographical error - the height should be 1100 millimeters not 1100 meters. I am looking for the formula to calculate the force generated by the bottom roller pulling the wet blanket or wet sheet of heavy cloth.

 

[IRstuff]

(Weight + spring force) as discussed several times above

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[3DDave]

So, rolling resistance over a wet cloth? It depends on how hard it's being squeezed. Next up, how much force to extrude some amount of water from some sort of fabric - that's going to require an experiment.

 

[Turn_of_the_Screw]

Agreed. You are not going to be able to calculate this. Assuming your ultimate goal is to achieve a certain tension on the cloth, your best bet is probably to find a way to adjust the force on the top roller (maybe a couple of springs and screws, for example). Once you can adjust the force, you can increase or decrease the force on the roller, which will increase pressure on the cloth, which will increase tension on the cloth from rolling resistance. Good Luck!

Chris