Variable Crown Roll
02-04-2009, 06:14 AM,
#1
Question  Variable Crown Roll
I have a customer asking if there is a coating (HVOF hopefully) that could withstand the forces of a variable crown.


This roll is one long roll with hydraulic pressure inside to deflect the outer shell symmetically, with curve / crown height range from 0 - 2 mm.
PM# 1 Calender 560 mm x 4065 mm..

This calendar is swimming roll type originally steel roll without coating but due to continuous apply of liquid PVA ( Poly Vinyl Alcohol ) then the surface has chemical corrosion which cause plenty of pitting holes.

Possibly we should we consider plastic coating?
Stephen James Booth
www.ipsteknokraft.com
www.teknokraft.com
Indonesia WhatsApp +6281905603262

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02-05-2009, 03:23 PM,
#2
RE: Variable Crown Roll
Hi Stephen

Not sure on this one. I calculate a possible coating strain rate of 0.75% which does not sound much, but is high for a coating. If you are coating this roll in situ in the machine, suggest spraying with roll in expanded/pressurised condition, so coating tends towards compressive stress rather than tensile. Also, thinner coatings will be better than thicker, though not for the corrosion aspect.

If hardness is not a primary concern, then a plastic coating may be worth consideration.
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02-06-2009, 02:24 AM,
#3
RE: Variable Crown Roll
(02-05-2009, 03:23 PM)Gordon Wrote: Hi Stephen

Not sure on this one. I calculate a possible coating strain rate of 0.75% which does not sound much, but is high for a coating. If you are coating this roll in situ in the machine, suggest spraying with roll in expanded/pressurised condition, so coating tends towards compressive stress rather than tensile. Also, thinner coatings will be better than thicker, though not for the corrosion aspect.

If hardness is not a primary concern, then a plastic coating may be worth consideration.

Thank you for the input. Considering the critical aspects of the job, size, expense, down time, etc. I am going to pass on this job. Would be keen to hear from the experts like Voith, Pikko, Bender on this type application.
Stephen James Booth
www.ipsteknokraft.com
www.teknokraft.com
Indonesia WhatsApp +6281905603262

Reply




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