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  1. tjwalker11

    Condution in low pressure vacuum

    To clarify, I'm asking about two surfaces in contact and the conduction heat transfer. Specifically heating a foil or film wrapping a heated roller. Is there a difference in the coefficient of thermal conductivity if this is done in atmosphere vs. in vacuum. I'm not talking about two surfaces...
  2. tjwalker11

    Condution in low pressure vacuum

    Does the conductivity coefficient between surfaces change is the conduction takes place in a low pressure vacuum? Does the lack of atmosphere significantly change conduction? I can imagine if two surfaces had 100% contact, that the atmosphere would have no effect, but most surfaces have some...
  3. tjwalker11

    Buckling in Curve Plate

    SparWeb (Steven), Thanks for your input. I've ordered a Roark's (didn't have one, but should of). As to your Qs: 1. Product can be coated on either side, but one-sided is the concern here. 2. Yes, you can do this, but the difficult goal is turning the web contact-sensitive side in, which you...
  4. tjwalker11

    Buckling in Curve Plate

    This "bow tie" shaped roller is commonly used as a anti-wrinkle design. However, when I design the geometry for anti-wrinkle, I try not to shift so much stress and strain to the edges that the middle goes to zero. What I'm interested in now is moving beyond this limitation to...
  5. tjwalker11

    Buckling in Curve Plate

    Steven, Happy to feed your curiosity... What percentage of the sheet is supported vs. unsupported middle? (This would usually be a low percent, say 0.25-1" on either side of a 8-14" wide web, but I'm wondering what the limits are...one of the reasons to find a model for this.) Is...
  6. tjwalker11

    Buckling in Curve Plate

    arto, can you tell me where I can get a copy of Benson's ASME paper...what conference / journal / year was this from? tjw
  7. tjwalker11

    Anti-Slip Tread for >450F, Corrosive Environment

    Thanks. That's a good idea. We had talked about sand-blasting (or as you've suggested grit-waterjet abrasion). We may have to revisit this option. This also addresses the need for "how to clean?" these rollers, besides emory cloth and steel brushes. Do you have any leads on who...
  8. tjwalker11

    Anti-Slip Tread for >450F, Corrosive Environment

    Yes, both "plasma" coatings (like a tungsten-polymer blend) and ceramic-polymer coatings MAY meet this requirement. Each of these options is likely $500+ per cylinder (which I have a number of), so I'm looking for a lower cost option. Machining the steel cylinders with a groove or...
  9. tjwalker11

    Anti-Slip Tread for >450F, Corrosive Environment

    I have an application that needs to bond a rough surface (Ra 300-2000) to a 5" radius cylindrical mild steel part. The challenge is the part is used in a >450F continuous and HCl vapor environment. Any suggestions for both the rough surface and bonding technique? I'd love to find a...
  10. tjwalker11

    Buckling in Curve Plate

    insideman, your thought isn't so wild. There are standard designs to float a tensioned web over a positively pressurized perforated cylinder, however, for this application, that is more complicated than we would like to use. I'm seeking the limits of undercut roller use, to know when more...
  11. tjwalker11

    Buckling in Curve Plate

    OK. Polyester films are coated for many applications, running in long continuous strips, 0.005" thick, 12" wide, 1000s ft long (give or take an order of magnitude on each). The film is run through a series of "rollers", with the wrap angle on a given roller of 10 to 180...
  12. tjwalker11

    Buckling in Curve Plate

    What would be the appropriate model for the buckling of a curved plate? I'm looking to understand buckling in thin films (0.005" thick polyester) when it is in a curved shape, like a half cylinder. This for printing press style handling systems, where the product is wrapped around a...

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