Draw furnace sealing assembly and method

Abstract

An apparatus and method for sealing the top of an optical waveguide draw furnace is disclosed. The apparatus includes an assembly constructed and arranged to removably cover the top of the draw furnace while mating with the downfeed handle. The apparatus includes an elongated sleeve having a base and a sealing mechanism positioned on the sleeve at a location remote from the base. The sleeve defines a chamber for receiving the downfeed handle, and the sealing mechanism is arranged with respect to the sleeve to mate with the downfeed handle received in the chamber. In one aspect of the invention, the apparatus further includes an inert gas purge for providing an inert atmosphere within the chamber. A method of sealing the top of an optical waveguide draw furnace is also disclosed.

What is claimed is:  
     
         1 . An apparatus for cooperating with a downfeed handle to seal the top of an optical waveguide draw furnace, said apparatus comprising: 
 an assembly constructed and arranged to removably cover the top of the draw furnace and mate with the downfeed handle, said assembly comprising an elongated sleeve having a base and defining a chamber for slidably receiving the downfeed handle therein; and    an inert gas supply communicating with said assembly to selectively deliver inert gas into the chamber.    
     
     
         2 . The apparatus of  claim 1  wherein said assembly further comprises a sealing mechanism supported by the elongated sleeve to mate with the downfeed handle.  
     
     
         3 . The apparatus of  claim 3  wherein said sealing mechanism comprises a circumferential gasket remote from the base, the gasket being positioned with respect to the sleeve such that the gasket conforms to the periphery of the downfeed handle.  
     
     
         4 . The apparatus of  claim 3  wherein said assembly further comprises a spring interposed between said sealing mechanism and the gasket to bias the gasket against the handle.  
     
     
         5 . The apparatus of  claim 1  wherein said inert gas supply comprises a gas selected from the group consisting of nitrogen, helium, or argon.  
     
     
         6 . The apparatus of  claim 1  wherein said inert gas supply comprises argon, and wherein said inert gas supply is adapted to selectively deliver the argon into the chamber between the gasket and the base.  
     
     
         7 . The apparatus of  claim 1  wherein said assembly further comprises a bottom plate for cooperating with the top of the draw furnace to prevent air from entering the draw furnace.  
     
     
         8 . An apparatus for cooperating with a downfeed handle to seal the top of an optical waveguide draw furnace, said apparatus comprising: 
 an elongated sleeve having a top and a base, said sleeve defining a chamber for receiving the downfeed handle; and    a sealing mechanism positioned on said sleeve at a location remote from the base, said sealing mechanism being arranged with respect to said sleeve to mate with the downfeed handle received in the chamber.    
     
     
         9 . The apparatus as claimed in  claim 8  wherein said sleeve further defines at least one port positioned between said sealing mechanism and the base to permit purging of the chamber.  
     
     
         10 . The apparatus as claimed in  claim 8  wherein said sealing mechanism comprises an annular gasket sized and shaped to conform to the shape of the downfeed handle.  
     
     
         11 . The apparatus as claimed in  claim 10  wherein said sealing mechanism further comprises at least one spring positioned with respect to the gasket to bias the gasket against the downfeed handle.  
     
     
         12 . The apparatus as claimed in  claim 8  wherein the base includes a bottom plate for cooperating with the top of the draw furnace to inhibit entry of non-selected gases into the draw furnace while permitting movement of said apparatus with respect to the draw furnace.  
     
     
         13 . A method of sealing the top of an optical waveguide draw furnace, said method comprising the steps of: 
 sliding an assembly onto a downfeed handle such that said assembly is supported on the downfeed handle, said assembly defining a chamber for receiving the downfeed handle, and comprising a base and a sealing mechanism remote from the base, said sealing mechanism cooperating with the downfeed handle to close one end of the chamber;    purging the chamber with a first inert gas; and    lowering the downfeed handle into the optical waveguide draw furnace to position the base of said assembly atop the draw furnace.    
     
     
         14 . The method of  claim 13  wherein said sealing mechanism comprises an annular gasket sized to conform to the periphery of the downfeed handle, and wherein the method further comprises the step of biasing the annular gasket against the downfeed handle.  
     
     
         15 . The method of  claim 13  further comprising the step of discharging a second inert gas between the base and the top of the draw furnace to suspend said assembly in close proximity with the top of the draw furnace.  
     
     
         16 . The method of  claim 13  wherein the step of purging includes the step of delivering argon into the chamber through a purge port entering the chamber between the sealing mechanism and the base.