U.S. patent application number 10/460342 was filed with the patent office on 2003-11-20 for drywall finishing trim having fiber covering fabricated with strengthening compound.
Invention is credited to Harel, Kenneth N..
Application Number | 20030213196 10/460342 |
Document ID | / |
Family ID | 25244874 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030213196 |
Kind Code |
A1 |
Harel, Kenneth N. |
November 20, 2003 |
Drywall finishing trim having fiber covering fabricated with
strengthening compound
Abstract
A drywall trim device incorporating a core covered on the
exterior by a cover strip fabricated from fibers mixed with a
strengthening compound to fill the interstices formed between the
fibers. The method of the invention may involve mixing the
strengthening compound with the fibers in a beating process,
rolling the fiber and compound into a film or layer to fill the
interstices between the fibers.
Inventors: |
Harel, Kenneth N.; (Anaheim,
CA) |
Correspondence
Address: |
FULWIDER PATTON LEE & UTECHT, LLP
200 OCEANGATE, SUITE 1550
LONG BEACH
CA
90802
US
|
Family ID: |
25244874 |
Appl. No.: |
10/460342 |
Filed: |
June 11, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10460342 |
Jun 11, 2003 |
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09825766 |
Apr 3, 2001 |
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Current U.S.
Class: |
52/287.1 ;
162/141; 52/717.04 |
Current CPC
Class: |
Y10T 428/24628 20150115;
B32B 15/14 20130101; E04F 13/068 20130101; B32B 2607/00 20130101;
E04F 13/06 20130101; E04F 2013/063 20130101 |
Class at
Publication: |
52/287.1 ;
52/717.04; 162/141 |
International
Class: |
E04B 002/00 |
Claims
What is claimed is:
1. A drywall trim device for drywall construction, comprising: an
elongated core having an outwardly facing bonding surface; a
covering strip including a plurality of flexible fibers formed with
interstices therebetween and a strengthening compound intermingled
with the fibers during the manufacturing of the strip to
substantially occupy the interstices; and a bond bonding the
covering strip to the bonding surface.
2. The drywall trim device of claim 1 wherein: the strengthening
compound also encapsulates the fibers during the manufacturing of
the strip.
3. The drywall trim device of claim 1 wherein: the fibers are
cellulose.
4. The drywall trim device of claim 1 wherein: the fibers are
synthetic.
5. The drywall trim device of claim 1 wherein: the covering strip
includes a plurality of layers.
6. The drywall trim device of claim 1 wherein: the covering strip
includes three layers.
7. The drywall trim device of claim 1 wherein: the covering strip
is formed with a predetermined thickness; and the strengthening
compound substantially occupies the interstices to a substantially
uniform concentration throughout the thickness.
8. The drywall trim device of claim 7 wherein: the strengthening
compound also encapsulates the fibers to a substantially uniform
concentration throughout the thickness.
9. The drywall trim device of claim 1 wherein: the core is
metal.
10. The drywall trim device of claim 9 wherein: the metal is
galvanized steel.
11. The drywall trim device of claim 1 wherein: the strengthening
compound is latex.
12. The drywall trim device of claim 1 wherein: the bond is
glue.
13. The drywall trim device of claim 1 wherein: the bond is defined
by a self-adhesive surface that is integral to the strip.
14. A drywall trim comprising: an elongated core having an outer
surface; a covering strip fabricated by mixing fibers during the
manufacturing process with means for inhibiting the contraction of
such strip at elevated temperatures; and a bond bonding the strip
to the outer surface.
15. The drywall trim of claim 14 wherein: the strip is formed with
the fibers forming interstices therebetween, and includes filler
means for substantially occupying the interstices.
16. A drywall trim comprising: a core having an outer surface; a
covering strip including bonded fiber segments formed with
interstices therebetween, the covering strip being fabricated by
mixing the fiber segments during the manufacturing process with a
filler means for inhibiting the concentration of moisture in the
interstices; and a bonding means for bonding the covering strip to
the outer surface.
17. The drywall trim of claim 14 wherein: the filler means further
inhibits the contraction of the strip relative to the core upon
exposure to a reduced humidity environment.
18. The drywall trim of claim 14 wherein: the filler means further
inhibits the contraction of the strip relative to the core upon
exposure to an increased temperature environment.
19. The drywall trim of claim 18 wherein: the fiber segments are
mixed during the manufacturing process with an encapsulating means
for encapsulating the fiber segments.
20. A method of making a drywall trim for use in drywall
construction, including: selecting a metallic core having an outer
surface; manufacturing a material layer that includes fibers formed
with interstices therebetween by mixing the fibers with a
strengthening compound that substantially occupies the interstices;
making a covering strip from the material layer; and adhering the
strip to the outer surface to provide a cover to the core.
21. The method of claim 20 that further includes: mixing the fibers
with a strengthening compound that encapsulates the fibers.
22. The method of claim 20 that further includes: manufacturing
multiple material laminations of said fibers mixed with said
strengthening compound; and combining such laminations to form said
layer.
23. A drywall trim device for dry wall construction prepared by a
process, including the following steps: selecting a metallic core
having an outer surface; manufacturing a material that includes a
strengthening compound and bonded cellulose fibers formed with
interstices therebetween by mixing the strengthening compound with
the fibers to substantially occupy the interstices; making a
covering strip from the material; and adhering the strip to the
outer surface.
24. The drywall trim device of claim 23 wherein: the strengthening
compound is mixed with the fibers to encapsulate the fibers.
25. A method of manufacturing a covering strip to cover a
predetermined surface area of a drywall trim core, including:
selecting cellulose fibers; selecting a strengthening compound;
mixing the fibers together to form interstices therebetween and
with the strengthening compound to form a mixture with the
strengthening compound substantially filling the interstices;
forming the mixture into a sheet; and cutting the covering strip
from the sheet to a size to cover the predetermined area.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation-in-part of my co-pending patent
application Ser. No. 09/825,766, filed Apr. 3, 2001, now U.S. Pat.
No. ______, which is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to drywall finish trim devices
typically utilized in finishing a drywall installation at a corner
or terminus.
[0004] 2. Description of Related Art
[0005] Drywall, sometimes also referred to as wallboard, is a
staple in the construction industry as an economical alternative to
plaster for forming the interior walls and ceilings of rooms in
residential, commercial, and industrial buildings. The materials
used in drywall construction include gypsum board, plywood,
fibre-and-pulp boards, and asbestos-cement boards. The large, rigid
sheets are fastened directly to the frame of a building with nails,
screws, or adhesives, or are mounted on furring (strips of wood
nailed over the studs, joists, rafters, or masonry, which allow
free circulation of air behind the interior wall). A significant
advantage afforded by drywall construction is that it allows a
builder to avoid delays because the interior walls do not have to
dry before other work can be started or to obtain specific
finishes. Wallboard is manufactured in both finished and unfinished
forms, and finished wallboards may be faced with vinyl or other
materials in a variety of permanent colors and textures so that
they do not need to be painted when installed.
[0006] When employing drywall in construction, builders can easily
cut the panels to any desired shape and size. However, workmen face
a challenge in finishing drywall panels at an edge or corner. It is
very difficult, if not impossible, to cut the edges of such panels
with the precision, straightness, and smoothness that is required
to abut the edges of adjoining panels to form a straight corner
that will afford an aesthetic finish. Additionally, cutting of the
drywall panels exposes the soft, raw cores thereof, thus requiring
some sort of covering to afford a finished appearance.
[0007] As a result, to protect the drywall panel edges and enhance
their aesthetic appearance, several devices and techniques may be
employed in an effort to produce a structurally sound corner that
will exhibit a smooth and seamless intersection. Devices proposed
to achieve this result include drywall tape, trim and corner beads.
When conventional drywall tape is used, it is applied to the joints
and edges of abutting panels and is covered with wet joint compound
that is feathered and smoothed to cover the newly created seams.
When the joint compound has dried, the tape and drywall can be
sanded, painted, covered, or otherwise finished in whatever manner
is desired. A great deal of skill is required, however, to apply
and form the joint compound to create a sufficiently straight
intersection that will exhibit, when taped and sanded to a finish,
no evidence of scuffing and tearing in the tape.
[0008] In light of the limitations of drywall tape, trim strips or
corner beads are often utilized in effort to produce a seamless and
aesthetically pleasing edge trim or intersection at the corners of
drywall panels.
[0009] Such trim may take many different forms and are typically in
the form of an angle corner bead having diverging flanges or may
be, for instance, a J strip to cap the edge of a dry wall panel.
For the purposes of this invention, the particular configuration is
not critical but use in conjunction with numerous different
configurations is contemplated. For instance, the trim may be flat
or configured with any one of a number of well known
configurations, including corner trim with perpendicular flanges,
corner trim with a rib formed at the juncture of the flanges
defining a bead, flanges angled at 135.degree. to one another,
those configured with somewhat of a Z shape, those with soft line
corners, and those with offsets or other configurations
traditionally used in the trade and known to those skilled in the
art.
[0010] To enhance the finished appearance of finished drywall made
with such trim, efforts have been made to provide such trim with an
exterior covering of paper or paper-like material to facilitate a
finishing strip. It is recognized that by covering a metal core
with paper, the paper surface may be covered during the finishing
process with a joint compound which is then sanded off and
feathered in effort to provide a smooth and continuous surface.
[0011] A disadvantage arising from the use of such paper covered
trim cores is that, during the sanding process, the workman might
sand through such compound and sand into the paper layer. This
sanding tends to scuff up the fiber in the paper layer leaving
somewhat of a scuffed or abraded surface, oftentimes with frayed
fiber ends. This results in a discontinuous and unattractive
surface. When finished, as by paint or the like, a somewhat fuzzy
and porous appearance may result with the exposed fibers and fiber
ends presenting an aesthetically unpleasing finish.
[0012] Efforts to solve this problem have led to the development of
various different trims and corner beads. One such corner bead
available in the market is a corner flange having a hard core
covered on the exterior with kraft paper, which is then coated with
latex. This product has proven somewhat unsatisfactory in the
marketplace. First, the latex coating is oftentimes without
uniformity in thickness and is often ineffective to provide
protection against penetration and fraying by the roughened surface
of a finish tool, such as sandpaper. Frequently, the workman will
in certain areas sand through the latex coating, thus raising the
fibers from the underlying paper and resulting in a dissatisfactory
final appearance. A corner bead of this type is shown in U.S. Pat.
No. 5,131,198 to Ritchie.
[0013] In recognition of the shortcomings of such surface coated
paper covering the core of drywall trim, other efforts have been
made to provide a more acceptable paper coating for trim core.
Corner beads have been proposed that are constructed of a core
covered by a wood fiber kraft paper impregnated with latex. Efforts
have been made to impregnate such stock paper to a uniform
thickness. A device of this type is shown in U.S. Pat. No.
5,613,335 to Rennich. While suitable for its specifically intended
purpose, such a bead suffers a shortcoming in that efforts to
penetrate paper stock with latex have proven relatively ineffective
to provide satisfactory scuff resistant characteristics throughout
the thickness of the paper covering.
[0014] Other shortcomings of prior drywall trims covered with paper
or paper-like covering are evident to those skilled in the art. The
paper covering of such drywall trims is generally formed with
fibers that are mixed together, dried and matted into a finished
strip. These fibers, generally being cellulose, will absorb water
both in the fibers and in the interstices formed between the
fibers. Then, when subjected to a low moisture environment, the
strip may tend to shrink as the moisture held in the fibers, or in
the interstices therebetween, evaporates. This is especially true
when they are subjected to high temperatures above about
100.degree. F., as may be encountered in high temperature
environments, low moisture climates or during storage in storage
sheds or in transportation thereof. In such instances, as the paper
covering shrinks, it will often bubble up on the core or will pull
away from the core, particularly in the area of any irregularity in
the core surface as in the case of any shoulder or rib formed in
such core. This bubbling and separation of the paper covering is
often detected only at the construction site after the product has
been transported and stored for preparation of the drywall phase of
the construction project. The onsite workman must often reject and
discard any strips of such deteriorated trim, or replace beads
where the defect becomes evident after installation, thus leading
to significant waste.
[0015] Consequently, there exists a need for a drywall trim that
will resist scuffing. It would also be beneficial if such a trim
would resist separation of the cover from the core of the trim to
thus minimize waste while enhancing the ultimate aesthetics of the
finished product.
SUMMARY OF THE INVENTION
[0016] The drywall trim device of the present invention is
characterized by a metal core covered on at least a portion of the
exterior side by a cover bonded thereto. The cover is fabricated by
mixing a mixture of fibers with a strengthening compound during the
manufacturing process to encapsulate the fibers and fill the
interstices formed therebetween with such strengthening compound.
This mixture is then formed into a strip that forms the cover.
[0017] The strengthening compound preferably acts as a filler in
the interstices formed between the network of fibers in order to
cooperate with the encapsulation of the fibers to minimize any
shrinkage or expansion of the covering material relative to the
core as a result of a variety of conditions such as high
temperatures or low humidity that may be present in the ambient
environment during use, transportation or storage.
[0018] The trim may be manufactured by fabricating a metal core
which can be formed to any desired configuration as dictated by the
end use thereof. Strengthening compounds, such as latex, may be
mixed with the fiber material in a beater mixing process typically
utilized in the manufacture of paper used for book covers and the
like. The exemplary fiber and latex mix may be formed in a thin
film, and multiple films may be combined together to form a
covering strip. The individual films or combined layers thereof may
then be pressed to the desired thickness and to enhance the
smoothness of the surface.
[0019] Other objects and features of the invention will become
apparent from consideration of the following description taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a diagrammatic view of the fibers of the pulp
being mixed with water to make a cover strip used in the drywall
finish trim device of the present invention.
[0021] FIG. 2 is a diagrammatic view of a latex being added to the
pulp mixture to encapsulate the individual cellulose fibers;
[0022] FIG. 3 is a perspective view depicting the pulp mixture
being deposited on a fabric web for drying;
[0023] FIG. 4 is a perspective view of a fibrous layer as it dries
on the fabric web;
[0024] FIG. 5 is a perspective view, similar to FIG. 4, but showing
the fibrous layer as it is removed from the web;
[0025] FIG. 6 is a diagrammatic view of paper layers fed from three
rollers to be combined and bonded into a covering strip;
[0026] FIG. 7 is a cross sectional view in enlarged scale taken
from the circle designated 7 in FIG. 6;
[0027] FIG. 8 is a transverse cross sectional view in enlarged
scale of a core covered by the covering strip shown in FIG. 6;
[0028] FIG. 9 is a cross sectional view in enlarged scale taken
from the circle designated 9 in FIG. 8 depicting the three layered
covering strip adhered to the core element;
[0029] FIG. 10 is an end view of a hard-line corner bead made in
accordance with the present invention, and with the thickness of
the core and covering strip being exaggerated for the purposes of
illustration;
[0030] FIG. 11 is an detailed sectional view in enlarged scale
taken from the circle designated 11 in FIG. 10.
[0031] FIG. 12 is a side view of a soft-line corner bead made in
accordance with the present invention, and with the thickness of
the elements being exaggerated for the purposes of
illustration;
[0032] FIG. 13 is an enlarged detailed sectional view taken from
the circle designated 13 in FIG. 12.
[0033] FIG. 14 is a cross sectional view taken from the circle
designated 14 in FIG. 11, depicting the three layered covering
strip adhered to the core element;
[0034] FIG. 15 is a cross sectional view taken from the circle
designated 15 in FIG. 13, depicting the three layered covering
strip adhered to the core element;
[0035] FIG. 16 is an end view of a third embodiment of the drywall
trim device of the present invention;
[0036] FIG. 17 is an end view of a fourth embodiment of the drywall
trim device of the present invention; and
[0037] FIG. 18 is a diagrammatic view depicting fiber segments and
strengthening compound incorporated in a protective cover on the
drywall trim device of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] As shown in the drawings and for purposes of illustration,
the present invention provides for an improved drywall trim having
a cover that is resistant to scuffing and abrasion. The cover is
also manufactured to be resistant to separation from the core,
which may result from a variety of environmental conditions or
after prolonged use.
[0039] The core may be formed in many different shapes, such as
with orthogonal flanges for a perpendicular corner, a J shape for
edge capping, a 135.degree. splay to accommodate obtuse corners or
any other shape now in existence or which may be developed in the
future for facilitating the finish of drywall construction.
[0040] Referring to FIGS. 10-17, the drywall finish device of the
present invention may take the form of a corner finish angle,
sometimes referred to in the trade as a corner bead. Examples of
such corner beads are the hard line and soft corner beads 25 and
27, shown in FIGS. 10 and 11 respectively, and the conventional
corner bead 29 shown in FIG. 16. As noted above, other trim shapes
are well known to those skilled in the art and are contemplated to
be within the scope of this invention.
[0041] The respective trim devices 25, 27, 29 and 31 of the present
invention are all covered on at least one flange with a cover,
generally designated 35, fabricated by mixing fibers 37 (FIG. 18)
with a strengthening compound 39 during the manufacturing process
to encapsulate such fibers 37 with the compound. In this process,
the fibers begin to bond together and the strengthening compound is
intermixed to fill interstices 41 formed between the various fibers
37. Thus, with the strengthening compound 39 encapsulating the
fibers and filling the interstices 41 formed therebetween, the
finished cover 35 will resist expansion and shrinking that may
occur due to exposure to a cycle of absorption and subsequent
evaporation of excess moisture, and as a result, will be less
likely to warp, bubble, crack or otherwise separate from the core
26, 28, 32 or 34 (FIGS. 10-12 and 16-17).
[0042] The covering strip 35 is generally manufactured from a pulp
consisting of cellulose or synthetic fibers, water, and other
additives. These additives may enhance the strength, water
resistance, resistance to abrasions and weathering, and internal
fiber bonding of the covering strip material, which are
particularly desirable characteristics for a material used to cover
the various beads that may be utilized in drywall construction.
[0043] For example, to address the problems of scuffing and damage
to conventional paper strips used to cover metal or plastic cores
in paper beads, recent developments in the art have incorporated
more durable and resilient paper or other fiber based coverings to
protect the paper bead core. There are many manufacturing and
treatment methods for making such covering strips more durable and
resilient. Modem paper manufacturing techniques generally use the
cellulose fibers in wood pulp in combination with pulps from waste
paper or, for finer grades of paper, with fibers from cotton rags
or virgin, chemically pulped fiber. Chemical pulp that is made by
boiling a mixture of wood chips with either soda, sulfite, or
sulfate, may also be used in the process.
[0044] I have discovered that a hard finish, commercially available
paper, typically utilized in book covering will provide high
resistance to scuffing and abrasion and, when adhered properly,
will provide a reliable drywall trim. Such product is available
under the trade designation 88 Pound Bristol Flex From FiberMark of
Fitchburg, Mass. It is understood, for the purpose of my invention,
that I intend to include any type of covering which is made by
mixing fiber segments with any form of strengthening material
available to add resistance to abrasion, scuffing and moisture
absorption, including fiber and strengthening materials now in
existence or which might become available in the future.
[0045] To manufacture the covering strip 35, a beater 45 (FIGS. 1
and 2) may first be used to split and mash the fibers 37. This
mechanical squeezing and pounding of the fibers permits water to
penetrate their structure, causing swelling of the fibers and
making them more flexible. When the pulp 49 and water are combined
by the beater 45, the beaten fibers are also cut smaller, and bond
together more readily as the water is removed or drained away, thus
producing a more dense paper of higher tensile strength and lower
porosity. As an alternative to beaters, a continuous refiner known
as a pulper may be used to separate the pulp fibers. Blades in the
pulper transform the pulp or wastepaper into a smooth liquid or
paste mixture by emphasizing fiber brushing rather than cutting. It
is believed that by pre-mixing the fiber 37 and strengthening
compound 39 during the beating process, the body of the fibers are
compacted somewhat in the process and the latex serves to
encapsulate the bodies of such fibers to cause them to exhibit less
of a frayed or straggly configuration. This then results in the
fibers being less susceptible to the absorption of water or
expansion and contraction under variations in water content.
Additionally, as shown in FIG. 18, even in material compositions
formed with highly compacted fibers 37, there still remains
interstices 41 formed between such fibers. However, pre-remixing of
the strengthening compound 39 with the fibers 37 during the beating
process will cause the strengthening compound to fill the
interstices 41 between the fibers. When the mixture is formed into
the cover 35, the strengthening compound that fills the interstices
will further resist moisture absorption and result in the cover
being less susceptible to expansion and contraction due to
variations in moisture content.
[0046] The pulp may then be poured onto a wire screen, conveyors,
or a fabric web, where the water is drained away and the fibers
form a thin mat by bonding to one another. In the next step of the
manufacturing process, the matted fibers 37 forming the paper are
passed through a series of rollers to dry, press, and smooth the
paper. It is believed that this process may serve to press the
fiber bodies into an even more compacted state and to compress the
size of the interstices 41 to create a structure which is resistant
to water absorption and the consequent expansion or contraction
with the subsequent removal of water in a high temperature
environment. With the strengthening compound filing these
compressed in size interstices 41, the resistance of the paper to
moisture will be further enhanced. The paper may then be sized and
may be further treated with a variety of substances to further
prevent aqueous solutions from soaking into it or to add strength
and stiffness to the paper.
[0047] To transform the rolled paper into a final, usable state, it
must then be finished or converted. During conversion, the paper
may be coated, impregnated, or laminated with various additional
applied materials to improve its properties for special purposes.
The final overall strength of the paper is determined by the
following factors in combination: (1) the strength of the
individual fibers of the stock; (2) the average length of the
fiber; (3) the inter-fiber bonding ability of the fibers, which is
enhanced by the beating and refining action described above; (4)
the strengthening compound added to the fibrous mix during the
beating process and its ability to encapsulate the fibers and fill
the interstices therebetween; and (5) the structure and formation
of the sheet to include materials that may be added to the forming
paper during manufacturing or surface treatments applied after the
paper is formed.
[0048] For the present invention, it is also important to note
that, because paper or other fibrous materials formed by the above
described process are composed of randomly matted layers of fiber,
the structure has a varying degree of porosity. Thus, the ability
of fluids, both liquid and gas, to penetrate the structure is a
property that is highly significant depending on the intended
application of the paper, and is capable of being adapted to the
intended application by varying the conditions of manufacture. For
example, the porosity of a covering strip 35 may be reduced by
beating an easily hydrated pulp to extremely fine sizes to produce
a relatively dense sheet with very little void space. Also, in a
preferred embodiment, the addition of strengthening compound 39
during the beating process encapsulates the fibers 37 and/or
substantially occupies the interstices 41 therebetween in a
substantially uniform concentration throughout the area of the
finished covering strip 35, which further reduces its porosity and
increases its resistance to moisture absorption. In the
alternative, the resistance of the covering strip to the
penetration of water can be increased by treatment of the fiber
with materials that lack affinity for water, with little effect on
the sheet porosity. This can be achieved during the processing of
the pulp or by treating or sizing the paper after it is formed into
sheets. For example, the covering strip may be treated with a
coating material comprising a fine particle size, acrylic,
water-based synthetic resin emulsion that may be applied with a
brush, roller, or sprayer. When the coating dries, the surface of
the covering strip will be coated with a protective acrylic film
layer.
[0049] In effort to develop paper beads with a paper covering strip
of increased durability and resistance to scuffing and other
abrasive damage, prior work has focused on post manufacturing
techniques, i.e. coating or impregnating stock paper or a synthetic
fiber product with latex or another strengthening compound. Various
commercial cross-linked latex lattices have been proposed in an
attempt to penetrate the stock paper fiber layers. This
impregnation has been proposed to increase the paper's strength and
reduce its resistance to scuffing and abrasion throughout its
thickness. However, impregnation or other post-manufacturing
surface treatment methods may not be available to a large segment
of the industry, and may be cost prohibitive. They may also be
inadequate to sufficiently improve the strength and durability of
the paper to provide a desired level of resistance to scuffing and
water absorption. While impregnation may aspire to uniformly
penetrate the fiber layers, post-manufacturing treatments may not
adequately impregnate all layers throughout, and may leave the
internal or lower layers susceptible to weathering, moisture
absorption, abrasion, or scuffing. Additionally, when the bead
covered by the paper is exposed to high temperatures or dry
conditions during storage or use, the paper may dehydrate, shrink
and form ruptures in its fiber layers or bubble up and begin to
separate from the core, thereby defeating the benefits afforded by
paper beads.
[0050] In an effort to develop a corner bead with a suitable
covering strip capable of uniformly resisting abrasion and scuffing
throughout its thickness, which would also reliably adhere to a
metallic core without rupturing or bubbling up at elevated
temperatures and after exposure to weathering, I discovered that a
commercially available fibrous material was suitable for the
present invention. Such a material is commonly used for book covers
and is pressed during the manufacturing process to a thickness of
about 0.008 inches thick, though many other thicknesses will
suffice as it is only important that the cover be sufficiently
thick to afford the desired finish benefits.
[0051] Accordingly, as shown in FIGS. 1-2 and 18, the covering
strip 35 of the present invention consists of a cellulose or
synthetic fiber based pulp 49 that is combined in a beater mixing
process with a strengthening compound 39 that encapsulates the
fibers 37 and fills the interstices 41 formed therebetween to a
substantially uniform concentration throughout the mix. The mixture
is then applied to a fiber mat or other such drying device so that
the material may dry and form a laminate 50, as shown in FIGS. 3-5.
At the conclusion of or during the drying cycle, the layers 50 are
formed in rolls 53 (FIG. 6).
[0052] The laminate 50 may then, at some point during the curing
cycle, be rolled from the rolls 53 (FIG. 6) to be married together
in a covering web, generally designated 57, and then passed through
compression rollers 59 which apply the desired pressure to three
laminations of the layer 50. The pressure on the rollers 59 may be
adjusted to achieve the desired thickness, as about 0.008 inches
thick. By compressing the lamination layers 50 to a greater degree,
it is believed that the matting formed by the fibers 37 is likewise
compressed as the fibers themselves are further compressed to
minimize the bulk thereof while maintaining the strength and
resistance to scuffing and moisture absorption afforded by such
fibers.
[0053] The web 57 (FIGS. 6 and 7) may then be fully cured and cut
into strips, for instance 3 or 4 inches wide, and stored on rolls.
Then, the cores and covering strips may be married together.
[0054] To this end, cores 26, 28, 32 or 34 may be formed from
strips of metal fed off a roll and through rollers as is well known
in the art. For the preferred method, the strips for the respective
cores are selected of a width corresponding with the ultimate width
of the trim or bead to be formed. To facilitate bonding of a hot
glue, the metal strip and covering strips may be heated as they are
drawn off their rolls to prevent premature cooling of the hot glue
61. As shown in FIG. 9, the hot melt glue 61 can be applied to the
interface of the core and inside lamination 50 of the strip 35. The
cover strip 35 may then be perforated with perforation holes spaced
throughout as is common in the art. Then the respective core, with
the cover strip married thereto, can be run through forming rollers
to form the trim to the desired cross sectional configuration, as
for instance the configuration for one of the beads 25, 27, 29 or
31 (FIGS. 10, 12, 16 and 17). The formed trimming strip may then be
cut to the desired length, stacked and stored for subsequent
shipping.
[0055] It will be appreciated that, while being stored or during
shipment to the construction site, or even during normal use in
certain environments, the drywall trim of the present invention can
be subjected to significant variations in atmospheric conditions,
including temperature and humidity. Experience with trim and
drywall beads of the prior art has been that, during such
variations in temperature, the cover material on a core may dry out
at high temperatures and shrink relative to the core causing it to
pull away from the underlying core, thus creating gaps in the
coverage and resulting in loss of the value of the trim. I have
tested the trim made by the present invention by subjecting it to
temperatures for extended periods of time at 158.degree. to
168.degree. and up to 200.degree. F. Except for some minor
instances where the bonding process was improperly conducted, the
drywall trim has proven to withstand such high dry temperatures
without experiencing any significant degree of deterioration and
without separating, pulling away or bubbling up on the core. It is
believed that this results from the fact that there is relatively
minimal shrinkage of the cover strip as it is subjected to higher
temperatures and lower humidity, thus minimizing the separation
problem. By encapsulating the fibers 37 and filling the interstices
41 therebetween with the strengthening compound 39, the covering
material will be less porous and more resistant to moisture
absorption, which in turn may serve to inhibit the undesirable
expansion of the covering material and its tendency to warp or
separate from the core.
[0056] In comparing the structure of the fibers 37 mixed with a
latex strengthening compound 41 (FIG. 18) of the present invention
with those of the prior art under a microscope, I have confirmed
that, in the cover strip 35 of the present invention, the fibers 37
appear to be more compressed and less frayed than those in the
prior art construction. Furthermore, the interstices 41 between
overlapping and interwoven fibers appear to be more filled with the
strengthening compound 39, thus minimizing the porosity which might
otherwise draw humidity.
[0057] When a workman selects a trim fabricated by the method of
the present invention for installation, he or she can place that
trim along the edge of a drywall panel, or in or over a corner or
other joint in a drywall construction, to finish the drywall
assembly in a manner known to those skilled in the art. The workman
can attach, for instance, any one of the corner beads 25, 27, 29 or
31, for example, and apply joint compound thereover to the cover
strip 35. The desired number of layers will be applied and, once
cured, the sanding and smoothing operation may proceed.
[0058] Should a workman's finishing effort result in sanding
through the joint compound layer and into one or more laminates 50
of the cover 35, it will be appreciated that the exterior surface
thereof will be penetrated. In practice, I have discovered that
such penetration will result in only minimal scuffing and that any
fibers 37 severed or penetrated tend to experience relatively
little fraying and roughening due to their encapsulation with
strengthening compound 39, thus minimizing the scuffed appearance
of the end surface. This then serves to provide minimum
discontinuity in surface texture and appearance between the joint
material and cover strip surface. Consequently, any finish applied
will tend to have a relatively uniform appearance and will exhibit
only minimal discontinuity.
[0059] From the foregoing, it will be appreciated that the method
and apparatus of the present invention provides an economical and
convenient method of manufacturing a drywall trim which is highly
durable in practice and provides for an attractive finish to the
drywall project. The drywall trim is susceptible to many different
applications and is highly resistant to a wide degree of
atmospheric conditions without significant deterioration.
[0060] Various modifications and changes may be made with regard to
the foregoing detailed description without departing from the
spirit of the invention.
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