Glass manufacturing – Fiber making apparatus – With specified bushing – tip – or feeder structure
Reexamination Certificate
1999-07-06
2001-08-14
Colaianni, Michael P. (Department: 1731)
Glass manufacturing
Fiber making apparatus
With specified bushing, tip, or feeder structure
C065S134100, C065S134900, C065S135200, C065S471000, C065S474000, C373S028000
Reexamination Certificate
active
06272887
ABSTRACT:
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION
This invention relates generally to an apparatus for and method of producing continuous glass filaments, and in particular, to a bushing tip plate support assembly for a bushing in a filament forming apparatus. The invention is useful in the production of continuous glass filaments.
BACKGROUND OF THE INVENTION
In the manufacture of continuous glass filaments, glass is melted in a glass furnace and flows through a forehearth to one or more bushings in a filament forming apparatus. Each bushing has several nozzles or tips through which streams of molten glass flow. The quenched glass streams are mechanically pulled from the nozzles by a winding apparatus to form continuous glass filaments.
Conventional bushings may be either a remelt bushing or a direct-melt bushing. A remelt bushing melts cold glass in the form of marbles or other shapes in its upper section and then conditions the glass and passes it through the bushing nozzles from which the molten glass is attenuated. A direct-melt bushing is supplied with liquid glass at the desired temperature from a continuous supply flowing above the bushing in a channel called a forehearth. The direct-melt bushing only needs to condition the molten glass to a uniform temperature before it is attenuated.
A conventional filament forming apparatus
5
with a bushing is shown in FIG.
1
and is disclosed in U.S. Pat. No. 3,920,430 to Carey (Carey), the disclosure of which is expressly incorporated herein by reference. Filaments
20
are drawn from a plurality of nozzles
12
depending from a bottom plate
14
of the bushing
10
and are gathered into a strand
22
by a roller
42
. Size is applied to coat the filaments by a size applicator
40
. A reciprocating device
32
guides strand
22
, which is wound around a rotating collet
34
in a winding apparatus
30
to build a cylindrical package
24
.
The electrically heated bushing
10
is located below and in communication with a forehearth
50
which receives refined, heat-softened or molten glass from a melting furnace
52
. The bushing
10
is mounted in communication with an opening in the bottom of the forehearth
50
.
Conventional bushings include side walls, end walls, and a bottom plate defining a bushing body therebetween. The bottom plate may include more than 4,000 nozzles, preferably all at or close to a uniform temperature. The bottom plate may be referred to as a nozzle plate or tip plate as well.
Bushings condition the molten glass to a uniform temperature so the filaments are attenuated with uniform diameters. The temperature of the molten glass must be high enough to maintain the glass in a liquid state. Accordingly, bushings are subjected to high temperatures over their operating life.
As they lose heat to the ambient, the filaments are attenuated from the bushing nozzles by a winding apparatus that winds one or more packages simultaneously. In order to supply a sufficient amount of filaments to a winding apparatus, bushings have increased in size.
Larger bushings encounter several problems due to their size. It is difficult to maintain the nozzle plate of a large bushing at a uniform temperature and achieve uniform diameter filaments. Also, it is difficult to minimize and control the distortion of the nozzle plate due to high operating temperatures and the weight of the molten glass in the bushing above the plate. Larger bottom plates are subjected to a greater overall load and tend to sag or creep sooner than smaller bottom plates. Hotter operating temperatures in the current state of the art processes also accelerate the high temperature creep of the tip plate alloys.
These problems result in creep and distortion of the bottom plate, which limit the useful life of a bushing. Creep is the deformation of the nozzle plate under a load and is a function of temperature and the stress on the plate. Distortion results when an insufficient allowance is made for the thermal expansion of the plate when the temperature in the bushing increases.
Several attempts have been made to solve these problems. One proposed solution involves the particular material of the bushing. Platinum materials may be used because they are resistant to oxidation and to corrosion by the glass and as a result, do not contaminate the glass. Platinum alloys are resistant to creep at elevated temperatures as well. However, pure platinum is soft and quickly distorts at high temperatures. While the addition to the platinum of an alloying material such as rhodium has proved beneficial, the particular material of the bushing alone is insufficient to eliminate the creep and distortion in the bushing bottom plate.
Another solution is to use various structures to support the bushing bottom plate. The supports used in a conventional precious metal fiberglass bushing include three principal components: a center support, an external support system, and an internal gusset system. Each of these components addresses sag, or high temperature creep, of the precious metal alloy for different areas of the bushing. Each component individually supports a different part of the bushing and it is preferable to have all three components to achieve the maximum service life for a bushing.
A conventional bushing with each of these support components is shown in FIG.
3
. The bushing
10
has a center support
70
and an external support system including external support straps
60
and external support brackets
62
. The bushing also has an internal support system that includes tip plate gussets
44
. The bushing shown in
FIG. 3
includes a frame
11
, side walls
16
,
18
, flanges
17
,
19
, and a V screen
15
through which molten glass flows. Filaments of molten glass are attenuated from nozzles
12
on bottom plate
14
.
The center support
70
is a flattened, water cooled nickel or stainless steel tube that is mounted beneath the tip section and external to the bushing tip plate. An example of a center support is described in detail in U.S. Pat. No. 4,055,406 to Slonaker et al. (Slonaker), which is expressly incorporated by reference herein. The function of the center support is to provide support between the two tip plates for a double bottom plate bushing configuration. For a single bottom plate bushing, the center support is the only one of the three components that is not required to support the bushing bottom plate.
The center support extends the entire length of the tip plates and is isolated from the bushing by an intermediate ceramic insulator. The relationship of the center support to a double bottom tip plate is shown in FIG.
3
.
Slonaker discloses a center support that includes a tubular body disposed lengthwise of and beneath the floor section of the bushing. Cooling fluid is circulated through the tubular member to minimize or reduce distortion or sagging of both the center support and the bottom plate of the bushing.
Turning to the external support system, the external support system shifts the mechanical support of the outer perimeter of a bushing from the castable refractory, which surrounds and insulates the bushing, to a bushing frame which is a more dimensionally rigid component. An example of the external support system is shown in
FIG. 3
as well.
The external support system consists of stirrups that are attached to each lower bushing side wall, ceramic insulating wafers, and stainless steel support straps
60
that extend from the stirrups to the lower surface of the bushing frame
11
. The external support system is intended to maintain the dimensional stability of the tip section along the perimeter of the bushing.
The center support and the external support system are external systems that support the bushing along the perimeters of each bottom plate. Support must be provided along the interior of the bottom plate as well.
The interior portion of the bottom plate is equipped with tip orifices for metering glass flow. Some conventional bushing are used with external cooling fin blades that are located between the nozzles to insure the re
Brown Kenny Alan
Emerson Jack Leonard
Purnode Bruno Andre
Smith Kevin Dewayne
Streicher William LaVerle
Colaianni Michael P.
Eckert Inger H.
Owens Corning Fiberglas Technology Inc.
LandOfFree
Bushing tip plate support assembly for a bushing in a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bushing tip plate support assembly for a bushing in a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bushing tip plate support assembly for a bushing in a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2537969