Heat transfer times ? 2

[tollie]

The problem
:To get .005 thick nickel cylinder 12.75 dia.X 80" long on a Steel cylinder .625 thick ,O.D.being.005-.008 bigger than the I.D. of the Nickel cylinder. Steel cylinder has been cooled with dry ice.Constant heat being applied to the nickle sleeve.
What is the possible time span to slide the nickel on? Can it be done?

Tollie

 

[sreid]

I think that chilling the cylinder will have a problem with ice build up from humidity in the air.

I would heat the screen in a heated tube (hundreds of degrees). The tube ID would be the size you want the expanded screen diameter to be. Then have a track with a carriage that aligns the cylinder and screen. Then slide them together quickly (seconds).

 

[tollie]

Sreid
Yes,On a hot humid day,lots of frost builds up.We have wrapped the shell in shrink wrap to prevent this build up.Removing the wrap just before the attempting to install the screen.
Your plan of using a tube to support the screen and heat it is a good one. This idea maybe of some help.
But I come back to the calulations.People can spend lots of time and money on ideas that fail.Where if it was thought about mathematicaly failure would have been evident.Money would have been saved and my life not so tormented. I like calulations that support ideas and theories. It gives an inspiration of hope that something can be achieved.
tollie

 

[ko99]

I hear you - even rough calculations could shed some light on the possibility of success. Someone on this forum may prove me wrong but I think your problem is beyond the scope of a set of formulas.

A transient CFD analysis can determine the rate of temperature change of the sheet and tube in some of the scenarios we discussed, at least if they are at fixed positions. It's much harder to add the effects of moving the sheet over the tube.

ko (

http://www.ecooling.biz)

 

[panduru]

If timbones could think out of the box, may I have the previlege of kinda thinking "inside the cylinder" please?

Is everyone's presumption that the inner steel cylinder is a solid cylinder and not a hollow cylinder, correct, in the first place?

If it is, is it really necessary? Would it not be possible to use a thin (just thick enough for the purpose) hollow inner cylinder?

My initial thinking was that, if at all necessary, this thin hollow cylinder could have threads inside and a solid cylinder could be threaded into it after the sleeve has been shrink-fit.

.

 

[ralph56]

Nice idea, pandura, tho it seems like the inner cylinder isn't the real problem. I figured it was a hollow thick-walled tube that could have dry ice inside it during the whole process but that was probably wishful thinking...

I like ko99's idea of clamping a heater around the screen.

 

[IRstuff]

Still seems like a more complicated process than necessary. The screen is supposedly etched and is supposedly used for printing.

So why can't the nickel be plated on the cylinder and etched in place using the inverse of the printing process?

TTFN

 

[panduru]

@IRstuff:
Because, I suppose, the etching process is flat, not rotary.

 

[tollie]

The product is a vacuum roll. The nickel screen would be a cover on the roll. The in side tube would be a 5/8 wall tube 12.75 dia.This has many holes drilled around the O,D, that the vacuum is pulled thru. The tube is bored ,honed and O.D. ground.The roll controls web tenison on converting machinery for the paper,film and foil industry.The screen provides micro holes that will not deform a coating or the very thin materail being coated.It also has a provides a fine finish 16rms maybe.
The operation to install the screen will be somewhat complex. If it was easy ,it would have already be done by now .This is what brings me here to maybe find brains better than ours.
Tollie

 

[IRstuff]

How big are the holes in the cylinder and the sheath?

TTFN

 

[IRstuff]

So how are competing products fabricated?

Is this process sufficiently cost effective, even it if worked? This sounds both labor and capital intensive and is not readily amenable to batch processing.

TTFN

 

[tollie]

I'm not sure of the size of the holes but they might be .005 .Screens are made on a mandral then the holes are etched into the screen.This is a bought item for us. The holes in the shell the screen goes on, there maybe 10's of thousands .093 holes depending on the size of the roll.
There is one roll maunfacture that has been sucessful in doing this .How they do it ?? We do'nt know
The converting machinery is somewhat custom.Vacuum rolls are used to control tension between operations.As coatings and the substrates get thinner and machines go faster.The rolls have to be able to handle the materails without destorting the products.This cover or screen would be highly desired for thin flim coating.

 

[IRstuff]

OK... I get the idea.

My personal druthers would be to start with the cylinder with its holes, use something like the wax for a lost wax process to temporarily fill in the holes. Deposit the nickel. Etch the nickel. Lose the wax.

TTFN