Glass manufacturing – Processes of manufacturing fibers – filaments – or preforms – Process of manufacturing optical fibers – waveguides – or...
Reexamination Certificate
1999-06-21
2001-07-17
Hoffmann, John (Department: 1731)
Glass manufacturing
Processes of manufacturing fibers, filaments, or preforms
Process of manufacturing optical fibers, waveguides, or...
C065S409000, C065S435000
Reexamination Certificate
active
06260389
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of making an optical fiber, more particularly to a method of prethreading a fiber through the apparatus employed to draw said fiber in a fiber draw process.
BACKGROUND OF THE INVENTION
Optical fiber is commonly made in a manufacturing process in which fiber is drawn from a glass preform into a thin strand of fiber many kilometers long. In most, if not all of these processes, this process begins with lowering a fiber preform into a furnace and heating it to a temperature sufficient to make the lower end of the preform sag into a gob. As the temperature of the lower end of the preform increases, this gob continues to narrow in diameter until it is sufficiently thin, and the viscosity of the glass is sufficiently low, to enable a strand of fiber to be continuously pulled from the preform.
The beginning of this process thus commonly involves threading the leading end of the fiber through the various apparatus employed in the fiber draw process, e.g., a fiber coating system for applying a protective coating onto the fiber, a fiber cooling system if one is employed, and various diameter measurement devices. The fiber is then attached to a device known as a tractor which continuously pulls the fiber through the draw apparatus, after which it is wound onto spools.
One way of accomplishing the initial task of threading the lead end of the fiber through the draw apparatus is to have the fiber manually thinned by a worker and then manually threaded down the draw tower and through the fiber cooling and coating systems, etc. During this process, the fiber often must be broken multiple times to maintain the proper diameter. In addition, the fiber often breaks by accident. In either case, the process of threading the fiber can become quite tedious and time consuming. In addition, stray fiber from this breakage often ends up in the cooling and/or coating systems, and can become a source of abrasions during the manufacturing process. If this occurs, it is often not detectable until after all of the fiber is drawn, in which case an entire spool of fiber may have to be scrapped. The difficulty with this process is magnified by the fact that these apparatus often occur on different floors of the manufacturing facility, and thus require more than one manual worker to thread the fiber through the apparatus. It is also magnified by the inconsistency from worker to worker in how the glass is thinned and the appropriate fiber diameter is determined prior to beginning the threading process. Adequately judging the proper fiber diameter can be crucial to the successful threading of the beginning of the draw process. Because of all the difficulties in manually threading the fiber by hand through the process, this process can sometimes take as long as 30 minutes or more to complete.
It would therefore be desirable to design an alternative method for feeding the leading edge of a fiber through the various apparatus of the draw process.
SUMMARY OF THE INVENTION
One aspect of the present invention relates to a method of threading a fiber in an optical fiber draw process, wherein a prethread filament is fed through the fiber draw process, the fiber is attached to the prethread filament, and the fiber is pulled through the process using the prethread filament. This method thus involves prethreading the filament through at least one component of the fiber draw process.
In one embodiment, one end of the prethread filament is fed through the component, and the other end of the prethread filament is fed into a coupling sleeve. The other end of the coupling sleeve is then used to capture the lead end of the fiber to be drawn from the preform. The lead end of the fiber can then be fed through the system simply by pulling the prethread filament back through the system.
There are a variety of materials that could be employed as the coupling sleeve. For example, conventional shrink tubing materials could be employed, as could adhesives or glues. Traditional glass splicing techniques (e.g., glass butt splicing techniques) could be employed if the prethread material is glass (e.g. glass fiber). Alternatively, a thin walled metal tube could be employed by crimping both ends of the metal tube about the lead end of the fiber and the trailing end of the prethread material. Alternatively, non-shrink tubes (e.g. tubes made of polyimide or polyester) could be employed, in which case the ends of the fiber and prethread could be attached therewith using glues to couple both ends inside the non-shrink tubes. In all of these embodiments, the outside diameter of the coupling sleeve is preferably narrow enough to fit through the various components of the fiber draw process, especially the coating applicator devices.
There are a variety of materials that could be employed as the filament. For example, metal wire, polyester filament, glass fiber (e.g. fiber optic filament), plastic materials, nylon and other materials could be employed successfully.
Coupling of the fiber to the prethread filament by the coupling sleeve can be achieved in a variety of methods, for example, melting or shrinking the coupling sleeve, melting both the sleeve and the filament, or melting only the filament. If desired, a glue or adhesive can be employed inside the coupling sleeve to join the ends of the prethread filament to the fiber.
Using the method of the present invention, threading of the lead end of the fiber in a draw process has been greatly facilitated. The time required for threading of the lead end of the fiber is greatly reduced, from a time which used to sometimes take as long as one half hour or longer, to a process which now takes minutes or less, once the proper diameter fiber is achieved. In addition, the quality of the resultant fiber is greatly improved, because the amount of broken fiber, which can, and often does end up in a location which could scratch the fiber, does not occur.
REFERENCES:
patent: 4486212 (1984-12-01), Berkey
patent: 4932740 (1990-06-01), Berkey et al.
patent: 5131735 (1992-07-01), Berkey et al.
patent: 5134470 (1992-07-01), Ravetti
patent: 5249246 (1993-09-01), Szanto
patent: 5674306 (1997-10-01), Hoshino et al.
patent: 5745626 (1998-04-01), Duck et al.
patent: 58-211709 (1983-12-01), None
Kelmer Kenneth J.
McElheny Douglas E.
Carlson Robert L.
Corning Incorporated
Hoffmann John
Wayland Randall S.
LandOfFree
Method of prethreading a fiber draw process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of prethreading a fiber draw process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of prethreading a fiber draw process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2457847