Method and apparatus for calendering a web
OwnerRonald D. Agronin, Paul J. Klemmerinventors
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Abstract
The invention comprises a method and apparatus for accurately calendering a web of material, such as paper. Zone control rolls of variable geometric profile are provided for a super calender at the top and bottom nips. The upper zone control roll has its geometric profile along the nip altered as a function of web caliper. The bottom zone control roll has its geometric profile altered as a function of temperature measured at the bottom compliant roll of the super calender.
Claims16
A method of calendering a web in a calender machine having a plurality of nips formed by roll pairs, to accurately control bulk, caliper and surface properties of the web comprising the steps of:
- (a) providing an upper zone control roll and a compliant roll to form the first nip;
- (b) providing a lower zone control roll and a compliant roll to form the final nip;
- (c) controlling the geometric profile of the upper zone control roll as a function of the caliper of the web exiting the final nip;
- (d) controlling the geometric profile of the lower zone control roll as a function of the temperature profile across the lower compliant roll,
- whereby controlling the geometric profile of the upper zone control roll permits accurate control of web caliper while control of the geometric profile of the lower zone control roll maintains control of gloss, and smoothness and protects the bottom compliant roll against excessive heat.
In an apparatus for calendering a web to determine bulk, caliper and surface properties and having a plurality of nips formed by roll pairs, the improvement comprising:
- (a) an upper zone control roll and a compliant roll forming the first nip;
- (b) a lower zone control roll and a compliant roll forming the final nip;
- (c) first means for controlling the geometric profile of the upper zone control roll as a function of the caliper of the web exiting the final nip;
- (d) second means for controlling the geometric profile of the lower zone control roll as a function of the temperature profile across the bottom compliant roll,
- whereby controlling the geometric profile of the upper zone control roll permits accurate control of web caliper while control of the geometric profile of the lower zone control roll maintains control of gloss, smoothness and protects the bottom compliant roll against excessive heat.
Dependencies are inferred from the claim text.