Glass manufacturing – Processes of manufacturing fibers – filaments – or preforms – With coating
Reexamination Certificate
1999-04-14
2001-03-13
Hoffmann, John (Department: 1731)
Glass manufacturing
Processes of manufacturing fibers, filaments, or preforms
With coating
C065S500000, C065S535000, C065S536000
Reexamination Certificate
active
06199406
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The instant invention relates to a gathering shoe arrangement for a continuous glass fiber forming operation.
2. Technical Considerations and Prior Art
Glass fibers are commonly formed by attenuating molten glass through orifices in a bushing. The fibers are then drawn across an applicator, which coats at least a portion of the fiber surface with a sizing composition. The coated fibers are then gathered into one or more discrete strands by gathering shoes and wound on a winding machine into a forming package. As a result of the glass fibers being drawn across the gathering shoes to form the strands, and in particular the friction developed between the fibers and the gathering shoes as the fibers contact the shoe, tension is added to the fibers. This additional tension in the fibers can result in degradation of the glass fibers as well as increased fiber breakage during the fiber forming and winding operation. Conversely, if tension can be reduced, the quality of the glass fiber product will improve.
The following patents disclose modified gathering shoe configurations.
U.S. Pat. No. 3,999,970 discloses a gathering shoe configured to reduce the wear of the shoe. The gathering shoe is formed from porous material, such as graphite. A gaseous fluid is introduced into a central cavity within the shoe and forced through slots in the porous material to the surface of the shoe such that the glass fiber strands formed by the shoe ride on a gaseous fluid cushion.
U.S. Pat. No. 4,526,598 discloses a gathering shoe which reduces the wrapping of fibers and/or strands around the shoe. The gathering shoe has an annular groove about its periphery. The groove includes plurality of holes radiating from the groove surface inward toward the center of the shoe.
It would be advantageous to reduce the tension in the fibers so as to improve the quality of the glass fiber strands.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for forming fiber strands comprising a fiber forming device, a gathering shoe device and a winder device, the improvement comprising a gathering shoe device which includes at least one gathering shoe having an annular groove for receiving the fibers from the fiber forming device, the gathering shoe having a generally circular cross section at the annular groove and a diameter at the annular groove ranging from about 2.54 to about 6.35 mm.
Another aspect of the present invention is an apparatus for forming fiber strands comprising a fiber forming device, a gathering shoe device and a winder device, the improvement comprising at least one gathering shoe having an annular groove for receiving the fibers from the fiber forming device, wherein the gathering shoe is sized such that there is a line of contact between the fibers within the annular groove and the gathering shoe ranges from about 0.0661 to about 1.661 mm.
Yet, another aspect of the present invention is a gathering shoe comprising a rod member having a longitudinal axis; and a groove extending circumferentially about the rod member, wherein the rod member has a diameter at the groove in the range of about 2.54 to about 6.35 mm.
Still, another aspect of the present invention is a method of forming fiber strands comprising the steps of attenuating fibers, gathering the fibers into at least one strand on a gathering shoe, and winding the strand, wherein the strand forming imparts a tension in the fibers, the improvement comprising the step of gathering the fibers on a gathering shoe having an annular groove for receiving the fibers, a generally circular cross section at the annular groove and a diameter at the annular groove ranging from about 2.54 to about 6.35 mm to reduce the strand tension.
Another aspect of the present invention is a method of forming fiber strands comprising the steps of attenuating fibers, gathering the fibers into at least one strand on a gathering shoe, and winding the strand, wherein the strand forming imparts a tension in the fibers, the improvement comprising the step of providing a line of contact between the fibers and the gathering shoe ranging from about 0.0661 to about 1.661 mm.
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The Manufacturing Technology of Glass Fibres, by K. L. Loewenstein (3rd Ed 1993) pp. 237-291.
The Manufacturing Technology of Glass Fibres, by K. L. Loewenstein (3rd Ed 1993) pp. 85-107 and 115-235.
The Manufacturing Technology of Glass Fibres, by K. L. Loewenstein (3rd Ed 1993) pp. 30-44, 47-60, 115-122 and 126-135.
The Manufacturing Technology of Glass Fibres, by K. L. Loewenstein (3rd Ed 1993) p. 25.
Hoffmann John
PPG Industries Ohio Inc.
Siminerio Andrew C.
LandOfFree
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