Caliper control system and method

Claim 2

In a system for treating a web of material: a rotating calender roll which presses against the web and varies in diameter with changes in temperature, an axially elongated cylindrical curved faceplate positioned coaxially of the roll with the front surface of the faceplate in close facing proxmity to the outer surface of the roll, a plurality of discharge openings spaced axially along the faceplate, plenum means in fluid communication with the discharge openings, and including said faceplate as a portion thereof, blower means for delivering room temperature air under pressure to said plenum means, a sensor for monitoring the caliper of the web after it is pressed by the roll, and means responsive to the sensor for selectively controlling along a plurality of axial zones the temperature of the air passing through the discharge openings to selectively heat or cool portions of the roll to control the caliper of the web including a plurality of individually controlled electrical heating elements associated with respective zones positioned behind the faceplate for selectively heating the air passing throgh proximate discharge openings to provide air in adjacent zones having a significant temperature differential.

Claim 3

The system of claim 1 wherein said blower means provides a continuous flow of said room temperature air along all of said zones whereby selectively heated air is confined to one said zone.

Claim 4

The system of claim 1 wherein the discharge openings comprise elongated slotted openings oriented with their long dimensions generally parallel to the axis of the roll.

Claim 5

The system of claim 1 including a plurality of axially extending baffle bars projecting from the outer surface of the faceplate.

Claim 6

The system of claim 1 wherein the discharge openings are oriented to direct the air into the region between the faceplate and the roll with a component of velocity in the direction in which the surface of the rotating roll travels past the discharge openings.

Claim 7

In a system for treating a web of material: a rotating roll which presses against the web and varies in diameter with changes in temperature, an axially elongated cylindrically curved faceplate positioned coaxially of the roll with the front surface of the faceplate in close proximity to the outer surface of the roll, a plurality of discharge openings arranged in two circumferentially spaced axially extending rows, one of said rows being positioned near one edge of the faceplate and the other of said rows being positioned centrally between the edges of the faceplate, means for delivering air through the discharge openings at high velocity into the region between the faceplate and the roll, a sensor for monitoring the caliper of the web after it is pressed by the roll, and means responsive to the sensor for controlling the temperature of the air passing through the discharge openings to selectively heat or cool portions of the roll to control the caliper of the web including a plurality of individually controlled heating elements positioned behind the faceplate for selectively heating the air passing through different discharge openings.

Claim 8

In a system for treating a web of material: a rotating roll which presses against the web and varies in diameter with changes in temperature, an axially elongated cylindrically curved faceplate positioned coaxially of the roll with the front surface of the faceplate in close proximity to the outer surface of the roll, a plurality of discharge openings arranged in two circumferentially spaced axially extending rows, one of said rows being positioned near one edge of the faceplate and the other of said rows being positioned centrally between the edges of the faceplate, means for delivering air through the discharge openings at high velocity into the region between the faceplate and the roll, a sensor for monitoring the caliper of the web after it is pressed by the roll, and means responsive to the sensor for controlling the temperature of the air passing through the discharge openings to selectively heat or cool portions of the roll to control the caliper of the web including a plurality of individually controlled heating elements positioned behind the faceplate for selectively heating the air passing through different discharge openings.

Claim 9

In a system for treating a web of material: a rotating roll which presses against the web and varies in diameter with changes in temperature, an axially elongated cylindrically curved faceplate positioned coaxially of the roll with the front surface of the faceplate in close facing proximity to the outer surface of the roll, a plurality of discharge openings comprising a plurality of circular apertures arranged in a plurality of circumferentially spaced axially extending rows along the faceplate, said faceplate including a plurality of circumferential grooves extending substantially between edges of the faceplate and axially-spaced along the faceplate, means for delivering air through the discharge openings at high velocity into the region between the faceplate and the roll, a sensor for monitoring the caliper of web after it is pressed by the roll, and means responsive to the sensor for controlling the temperature of the air passing through the discharge openings to selectively heat or cool portions of the roll to control the caliper of the web including a plurality of individually controlled heating elements positioned behind the faceplate for selectively heating the air passing through different discharge openings.

Claim 10

In a system for treating a web of material: a rotating roll which presses against the web and varies in diameter with changes in temperature, an axially elongated cylindrically curved faceplate positioned coaxially of the roll with the front surface of the faceplate in close facing proximity to the outer surface of the roll, a plurality of discharge openings comprising a plurality of circular apertures arranged in a plurality of circumferentially spaced axially extending rows along the faceplate, said faceplate including a plurality of circumferential grooves extending substantially between edges of the faceplate and axially-spaced along the faceplate, means for delivering air through the discharge openings at high velocity into the region between the faceplate and the roll, a sensor for monitoring the caliper of web after it is pressed by the roll, and means responsive to the sensor for controlling the temperature of the air passing through the discharge openings to selectively heat or cool portions of the roll to control the caliper of the web including a plurality of individually controlled heating elements positioned behind the faceplate for selectively heating the air passing through different discharge openings.

Claim 11

The system of claim 1 wherein said faceplate includes a plurality of axial V-shaped grooves in which said discharge openings are placed.

Claim 12

The system as in claim 8 wherein said discharge openings are oriented to direct the air into the region between the faceplate and the roll with a component of velocity opposite the direction in which the surface of the rotating roll travels past the discharge openings.

Claim 13

In a method of treating a web of material with a rotating calender pressure roll which varies in diameter with changes in temperature where such diameter is varied by directing air at said roll through a plurality of axially spaced openings, arranged along a plurality of zones in the axial direction in an axially elongated cylindrically curved face plate in close facing proximity to the surface of the roll and where electrical heating elements are positioned behind said faceplate in each of said zones the steps of: providing from a single source at room temperature a continuous flow of air through said openings into the region between said faceplate and the roll; and selectively heating in a region proximate to said faceplate by activation of said heating elements said room temperature air before it exits through the proximate opening to provide air in adjacent zones having a significant temperature differential, said continuous flow of air exiting from adjacent zones preventing spreading to confine said heated air to one said zone.

Claim 14

In a method of treating a web of material with a rotating calender pressure roll which varies in diameter with changes in temperature where such diameter is varied by directing air at said roll through a plurality of axially spaced openings, arranged along a plurality of zones in the axial direction in an axially elongated cylindrically curved face plate in close facing proximity to the surface of the roll and where electrical heating elements are positioned behind said faceplate in each of said zones the steps of: providing from a single source at room temperature a continuous flow of air through said openings into the region between said faceplate and the roll; and selectively heating in a region proximate to said faceplate by activation of said heating elements said room temperature air before it exits through the proximate opening to provide air in adjacent zones having a significant temperature differential, said continuous flow of air exiting from adjacent zones preventing spreading to confine said heated air to one said zone.

Claim 15

A method as in claim 10 where said continuous air flow baths the surface of said faceplate in room temperature air absent said selective heating.

Claim 16

A method of claim 10 including the additional steps of monitoring the caliper of the web and controlling the heating of the air to adjust the diameter of the roll to produce a desired caliper.

Claim 17

The method of claim 10 wherein the air is directed through the openings at high velocity and in a direction such that the air bounces back and forth between the surfaces of the faceplate and the roll as it passes through the region between the faceplate and the roll.

Claim 18

The method of claim 10 wherein the air is maintained in a turbulent condition between the faceplate and the roll.

Claim 19

The method of claim 10 wherein air at room temperature is introduced under pressure into a plenum chamber in communication with the discharge openings.

Claim 20

A method as in claim 10 including the step of providing a plurality of axially spaced low pressure circumferential channels for exhausting air from the region between the faceplate and the roll.

Claim 21

A method as in claim 10 including the step of corrugating said faceplate to alter air flow direction for increasing relative arriving velocity to the roll surface.