Cross-directional smoothness controller and method of using the same
First Claim
1. An apparatus for discharging a controlled amount of steam against a sheet surface during calendering, comprising:
- a substantially impermeable calender roll;
discharge means for discharging steam against a location of the sheet surface where the opposing sheet surface is backed by the calender roll; and
a containing means, including a surface which substantially corresponds to the curvature of the calender roll, disposed in close proximity to the calender roll for substantially containing the discharged steam between the containing means and the sheet surface.
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Accused Products
Abstract
An apparatus for controlling the cross-directional smoothness profile of the surface of a calenderable material substantially independently of the materials'"'"'s caliper profile. A plurality of adjustable nozzles selectively direct jets of steam of selected velocities against sections of the material across the material'"'"'s width and in counterflow to its movement, immediately before the material enters the last nip of a calender stack. Built-in steam control valves are provided to control the amount of steam applied to each section. Suction means may also be provided upstream of the nozzles, with reference to the movement of the calenderable material, to remove excess steam and thus prevent undesirable condensation on adjacent structures. The smoothness profile may be monitored and compared to a desired smoothness profile and the valves and nozzles may be adjusted accordingly.
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Citations
24 Claims
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1. An apparatus for discharging a controlled amount of steam against a sheet surface during calendering, comprising:
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a substantially impermeable calender roll; discharge means for discharging steam against a location of the sheet surface where the opposing sheet surface is backed by the calender roll; and a containing means, including a surface which substantially corresponds to the curvature of the calender roll, disposed in close proximity to the calender roll for substantially containing the discharged steam between the containing means and the sheet surface. - View Dependent Claims (2, 3, 7, 8)
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4. An apparatus for discharging a controlled amount of steam against a sheet surface during calendering, comprising:
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a calender roll; and discharge means for discharging steam against a location of the sheet surface where the opposing sheet surface is backed by the calender, wherein the discharge means is disposed so that the discharged steam impinges on the sheet surface substantially counter to the direction of rotation of the calender roll. - View Dependent Claims (5, 6)
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9. A system for controlling a physical characteristic of a sheet being calendered, comprising:
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a calender stack including a plurality of calender rolls, wherein the calender stack has an upstream end and a downstream end and a plurality of nips formed between adjacent rolls of the calender stack; and a physical characteristic controller disposed to discharge fluid against the sheet immediately before the sheet is pressed at one nip of the calender stack, the one nip being located downstream from the nips affecting the desired caliper of the sheet, such that a physical characteristic of the sheet may be changed without affecting the desired caliper of the sheet. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for controlling a physical characteristic of a sheet being calendered, comprising the step of:
controllably discharging a fluid against the surface of the sheet at a location substantially immediately before the sheet enters one nip of a calender stack, the one nip being located downstream from the nips of the calender stack affecting the desired caliper of the sheet, such that a physical characteristic of the sheet may be changed without affecting the desired caliper of the sheet. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
Specification