Circumferentially variable surface temperature roller

Abstract

A casting roller having a variable temperature surfaces comprises a rotatable cylindrical shell ( 12 ). Axially aligned heating electric elements ( 14 ) are equally spaced and internal to an outer surface of the rotatable cylindrical shell. A brush assembly ( 16 ) is in electrical contact with the heating elements during a portion of the rotatable cylindrical shell rotation about an axis. A stationary core ( 26 ) is internal to the rotatable cylindrical shell. An annular space is between the stationary core and the rotatable cylindrical shell. A cooling fluid fills ( 22 ) at least a portion of the annular space.

1 . A casting roller having a variable temperature surface comprising: 
 a rotatable cylindrical shell;    axially aligned heating electric elements equally spaced and internal to an outer surface of said rotatable cylindrical shell;    a brush assembly in electrical contact with said heating elements during a portion of said rotatable cylindrical shell rotation about an axis;    a stationary core internal to said rotatable cylindrical shell;    an annular space between said stationary core and said rotatable cylindrical shell; and    a cooling fluid filling at least a portion of said annular space.    
     
     
         2 . A casting roller as in  claim 1  wherein a baffle confines said cooling fluid to a portion of said annular space.  
     
     
         3 . A casting roller as in  claim 1  wherein said cooling fluid is selected from a group comprising organic synthetic media that has an operating temperature range of 60 C to 350 C (140 F-662 F).  
     
     
         4 . A casting roller as in  claim 3  wherein the viscosity of the fluid varies from 8.2 centipoise to 0.26 centipoise.  
     
     
         5 . A casting roller as in  claim 3  wherein specific heat of said media varies from 1.62 kJ/kg*K at 60 C to 2.82 kJ/kg*K at 360 C.  
     
     
         6 . A casting roller as in  claim 3  wherein thermal conductivity varies from 0.125 W/m*K at 60 C to 0.086 W/m*K at 360 C.  
     
     
         7 . A casting roller as in  claim 3  wherein density of said media varies from 1016 kg/m3 at 60 C to 801 kg/m3 at 360 C.  
     
     
         8 . A casting roller as in  claim 1  wherein said heating elements are cartridge heaters.  
     
     
         9 . A casting roller as in  claim 8  wherein said heaters are 0.25 inch diameter with a heat flux output of approximately 60 W/in2.  
     
     
         10 . A casting roller having a variable surface temperature comprising: 
 a rotatable cylindrical shell;    a stationary core internal to said rotatable cylindrical shell;    an annular space between said stationary core and said rotatable cylindrical shell;    baffles creating a first and second region in said annular space;    a first fluid at a first temperature circulating in said first annular space; and    a second fluid at a second temperature circulating in said second annular space.    
     
     
         11 . A casting roller as in  claim 10  wherein said first fluid is a cooling fluid and is selected from a group comprising organic synthetic fluid has an operating temperature range of 60 C to 350 C (140 F-662 F).  
     
     
         12 . A casting roller as in  claim 11  wherein a viscosity of the fluid varies from 8.2 centipoise to 0.26 centipoise.  
     
     
         13 . A casting roller as in  claim 11  wherein a specific heat of said fluid varies from 1.62 kJ/kg*K at 60 C to 2.82 kJ/kg*K at 360 C.  
     
     
         14 . A casting roller as in  claim 11  wherein thermal conductivity of said fluid varies from 0.125 W/m*K at 60 C to 0.086 W/m*K at 360 C.  
     
     
         15 . A casting roller as in  claim 11  wherein a density of said fluid varies from 1016 kg/m3 at 60 C to of 801 kg/m3 at 360 C.  
     
     
         16 . A casting roller as in  claim 10  wherein said first annular space covers one third of the circumference of the shell at a time.  
     
     
         17 . A casting roller as in  claim 10  wherein said second annular space covers two thirds of said cylindrical shell at a time.  
     
     
         18 . A casting roller as in  claim 10  wherein: 
 said rotatable cylindrical shell is thin; and    a shoe supports said rotatable cylindrical shell at a nip.    
     
     
         19 . A method of casting a web of material comprising: 
 contacting said web within a heating zone of said roller;    raising said web to a casting temperature;    forming an impression on said web;    maintaining said web in contact with said roller through at least a portion of a cooling zone on said roller; and    stripping said web from said roller after said web has cooled.    
     
     
         20 . A method as in  claim 19  wherein said roller surface temperature is increased 30 degrees centigrade to 60 degrees centigrade greater than a web glass transition temperature.  
     
     
         21 . A method as in  claim 19  wherein said roller surface temperature is decreased to 3 degrees centigrade to 5 degrees centigrade less than a web glass transition temperature.  
     
     
         22 . A casting roller having a variable surface temperature comprising: 
 a rotatable cylindrical shell;    a stationary core internal to said rotatable cylindrical shell;    an annular space between said stationary core and said rotatable cylindrical shell;    baffles creating a first and second region in said annular space;    a first fluid at a first temperature circulating in said first annular space;    a second fluid at a second temperature circulating in said second annular space;    wherein said rotatable cylindrical shell is thin; and    a shoe which supports said rotatable cylindrical shell at a nip.    
     
     
         23 . A casting roller as in  claim 22  wherein: 
 a third region is created by said buffer surrounding said shoe; and    a third fluid at a third temperature is in said third region.    
     
     
         24 . A casting roller as in  claim 23  wherein said third fluid lubricates said shoe.