Pulling Rolls for Making Sheet Glass and Methods of Making and Using

Abstract

A pulling roll for glass manufacture made from a millboard material fired to minimize or eliminate weight loss during operation. Methods for preparing and using such a pulling roll are also disclosed.

1 . A pulling roll comprising a plurality of millboard pieces, wherein the plurality of millboard pieces have been fired at a predetermined temperature and time such that the pulling roll does not undergo a weight loss from thermal perturbations of more than 5% upon exposure to operating temperatures. 
     
     
         2 . The pulling roll of  claim 1 , wherein the plurality of millboard pieces have been fired prior to assembly of the pulling roll. 
     
     
         3 . The pulling roll of  claim 1 , wherein the predetermined temperature and time are such that the pulling roll does not undergo a weight loss from thermal perturbations of more than 3% upon exposure to operating temperatures. 
     
     
         4 . The pulling roll of  claim 1 , wherein the predetermined temperature and time are such that the pulling roll does not undergo a weight loss from thermal perturbations of more than 1% upon exposure to operating temperatures. 
     
     
         5 . The pulling roll of  claim 1 , wherein the temperature and time are determined from a thermal profile of at least a portion of the plurality of millboard pieces. 
     
     
         6 . The pulling roll of  claim 1 , wherein the plurality of millboard pieces have been fired at a temperature of at least about 750° C. for a period of at least about 4 hours. 
     
     
         7 . The pulling roll of  claim 1 , wherein the plurality of millboard pieces have been fired at a temperature of at least about 900° C. 
     
     
         8 . A method for manufacturing sheet glass, the method comprising forming a ribbon of glass using a fusion process including contacting at least a portion of the ribbon of glass with the pulling roll of  claim 1 , and then separating a sheet of glass from the ribbon of glass. 
     
     
         9 . A method for preparing a pulling roll, the method comprising:
 a. firing a plurality of millboard disks at a predetermined temperature and time, and   b. assembling the plurality of millboard disks on a pulling roll shaft to form a pulling roll,   
       wherein the predetermined temperature and time are such that the pulling roll does not undergo a weight loss from thermal perturbations of more than 5% upon exposure to operating temperatures. 
     
     
         10 . The method of  claim 9 , wherein the plurality of millboard disks are fired prior to assembly on a pulling roll shaft. 
     
     
         11 . The method of  claim 9 , wherein the predetermined temperature and time are such that the pulling roll does not undergo a weight loss from thermal perturbations of more than 3% upon exposure to operating temperatures. 
     
     
         12 . The method of  claim 9 , wherein the predetermined temperature and time are such that the pulling roll does not undergo a weight loss from thermal perturbations of more than 1% upon exposure to operating temperatures. 
     
     
         13 . The method of  claim 9 , wherein comprises heating at a temperature of at least about 750° C. 
     
     
         14 . The method of  claim 9 , wherein firing comprises heating at a first temperature and holding for a period of time, and then heating at a second temperature, wherein the second temperature is greater than the first. 
     
     
         15 . The method of  claim 9 , comprising prior to step a, determining the thermal profile of the millboard disks over an intended operational temperature range of the pulling roll. 
     
     
         16 . The method of  claim 9 , wherein the temperature is a temperature at which the plurality of millboard disks no longer lose weight from thermal perturbations upon exposure to the operational temperature range of the puling roll. 
     
     
         17 . A method for determining a heating program for a millboard material, the method comprising:
 a. monitoring the weight of a portion of the millboard material while heating at a furnace temperature of from about ambient to at least about a pulling roll operating temperature, and then   b. determining the temperature and time at which the millboard material should be fired such that a pulling roll formed from the millboard material does not undergo a weight loss from thermal perturbations of more than 5% upon exposure to the operating temperature.   
     
     
         18 . The method of  claim 17 , wherein step b comprises determining the temperature and time at which the millboard material should be fired such that a pulling roll formed from the millboard material does not undergo a weight loss from thermal perturbations of more than 3% upon exposure to the operating temperature. 
     
     
         19 . The method of  claim 17 , wherein step b comprises determining the temperature and time at which the millboard material should be fired such that a pulling roll formed from the millboard material does not undergo a weight loss from thermal perturbations of more than 1% upon exposure to the operating temperature. 
     
     
         20 . The method of  claim 17 , further comprising firing a plurality of millboard pieces at the determined temperature and time. 
     
     
         21 . The method of  claim 20 , further comprising assembling the plurality of millboard pieces, after firing, to form a pulling roll. 
     
     
         22 . The method of  claim 17 , further comprising assembling the plurality of millboard pieces, prior to firing, to form a pulling roll and then firing the pulling roll at the temperature and for the time.