U.S. patent application number 09/967320 was filed with the patent office on 2002-06-20 for paper bead.
Invention is credited to Kunz, Roland, Rantilla, Roy R..
Application Number | 20020073638 09/967320 |
Document ID | / |
Family ID | 24290335 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020073638 |
Kind Code |
A1 |
Kunz, Roland ; et
al. |
June 20, 2002 |
Paper bead
Abstract
A corner bead is of the tape-on type, having an elongated metal
core strip with a longitudinal arcuate nose and a pair of flanges
extending outwardly from the nose at approximately a right angle. A
cover strip of paper is bonded to the exterior surface of the core
strip, and includes wings which project outwardly beyond the extent
of the flanges. The cover strip is formed of a stock paper having
high abrasion resistance, tensile strength, and which is
dimensionally stable on contact with wet joint compound.
Inventors: |
Kunz, Roland; (Omaha,
NE) ; Rantilla, Roy R.; (Niles, OH) |
Correspondence
Address: |
MARK D. FREDERIKSEN
P.O. Box 938
Council Bluffs
IA
51502-0938
US
|
Family ID: |
24290335 |
Appl. No.: |
09/967320 |
Filed: |
September 28, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09967320 |
Sep 28, 2001 |
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09573022 |
May 17, 2000 |
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Current U.S.
Class: |
52/255 ;
52/256 |
Current CPC
Class: |
E04F 2013/063 20130101;
E04F 13/06 20130101; E04F 13/068 20130101 |
Class at
Publication: |
52/255 ;
52/256 |
International
Class: |
E04B 001/00 |
Claims
We claim:
1. A method for manufacturing a tape-on corner bead, comprising the
steps of: providing a strip of a paper of a type having high pick
resistance, high tensile strength, and dimensionally stable on
contact with wet joint compound; and bonding the paper strip to an
outward face of an elongated core with wings extending outwardly
beyond the extent of the core.
2. The method of claim 1, further comprising the step of forming a
plurality of spaced apart apertures through at least a portion of
said strip.
3. The method of claim 2, wherein the bonding step includes the
steps of: applying a continuous stripe of adhesive to one of said
paper strip and the core; and applying pressure to the core and
paper strip.
4. The method of claim 3, wherein the bonding step further includes
the step of heating the paper to a predetermined temperature prior
to the step of applying the adhesive stripe.
5. The method of claim 4, further comprising the steps of: roll
forming the core to a preformed shape with a cross-sectional shape
that begins to conform to the desired finished cross-sectional
shape, prior to the bonding step; and wherein the step of applying
pressure includes passing the core and paper strip through a series
of contoured forming rolls to form the core and attached strip into
the desired finished cross-sectional shape.
6. The method of claim 1, wherein the core is metal.
7. A tape-on corner bead for drywall construction, comprising: an
elongated core strip having a longitudinal arcuate channel forming
a nose, and a pair of flanges extending outwardly from each side of
the nose; a cover strip affixed to an outward face of the core
strip, with wings extending beyond the extent of the flanges; and
said cover strip formed of a paper with high pick resistance and
high tensile strength, and which is dimensionally stable when in
contact with wet joint cement.
8. The corner bead of claim 7, wherein said cover strip is a
non-latex-bearing paper.
9. The corner bead of claim 7, wherein said cover strip is neither
impregnated, nor coated with a strengthening compound.
10. The corner bead of claim 7, wherein the wings are perforated
with a plurality of apertures having diameters of approximately
0.005 to 0.020 inches.
11. The corner bead of claim 7, wherein the core strip is
metal.
12. The corner bead of claim 11, wherein the metal is galvanized
steel.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This is a continuation of Ser. No. 09/573,022, filed May 17,
2000, entitled "Corner Bead Drywall Trim and Method of
Manufacture".
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED
RESEARCH AND DEVELOPMENT
[0002] (Not applicable)
BACKGROUND OF THE INVENTION
[0003] (1) Field of the Invention
[0004] The present invention relates generally to drywall
construction, and more particularly to an improved corner bead
strip with paper wings.
[0005] (2) Background Information
[0006] Current building construction utilizes sheets of drywall,
commonly referred to as "wallboard", to form the surfaces of
interior walls of buildings. Drywall, or wallboard, is formed of
sheets of plaster which are sheathed in an outer wrapping of heavy
construction paper.
[0007] In wallboard construction, the joint between adjacent sheets
of wallboard is usually covered by a paper tape extending
lengthwise along the joint. The conventional drywall tape is
provided in narrow elongated strips of porous paper wound into
rolls. The drywall tape is applied to the joints, and then covered
with wet plaster or "mud". The plaster is feathered and smoothed
along the edges of the tape to conceal the tape edges and form a
smooth unmarred surface where the wallboard adjoins.
[0008] It is often necessary to cut the wallboard to form a corner,
which thereby exposes the plaster contained between the heavy paper
sheets. This exposed plaster tends to crumble unless these edges
are protected. To finish exterior corners in wallboard
construction, metal corner beads are typically installed. Such
corner beads are conventionally formed by roll-forming from an
elongated strip of sheet metal, and provide a rounded nose with two
mounting flanges extending at substantially right angles from the
opposing sides of the nose. These mounting flanges are often
knurled or embossed to provide a rough surface so that the joint
compound will adhere when the corner is finished.
[0009] The corner bead is installed by securing the mounting
flanges along the surface of the drywall panels adjacent to the
corner by nails or the like. Wet plaster is then smoothed into
place to cover the metal flanges, and edges of the plaster are
smoothed and feathered to cover and conceal the metal edges.
[0010] A second type of corner bead is referred to as a "tape-on"
bead. Tape-on corner beads utilize paper wings to secure a metal
corner angle in position, rather than using nails or other
fasteners. Wet plaster or joint cement for finishing the corner
will normally adhere significantly better to the paper cover strip
of tape-on beads, than to the exposed metal of conventional nail-on
beads. Nail-on beads are also typically more susceptible to
developing crack lines along the outer edges of the flanges, than
are tape-on beads. In addition, tape-on beads are more tolerant of
dimensional and geometric changes in the underlying construction
framing than are nail-on beads with their rigid mechanical
attachment to the construction framing.
[0011] One of the main problems with prior art tape-on bead is the
use of standard joint/drywall tape-on the bead. Such drywall tape
is very fibrous, which is good for bond strength, but poor for
appearance. During the application of joint cement over the tape,
to adhere the corner bead to the drywall, fibers will project and
protrude with only minimal contact by the application tools. These
fibers will ball up during the course of sanding of the joint
cement for the final finish, thereby detracting from the finished
appearance of the corner.
[0012] One method for improving protection against adverse abrasion
of this paper strip is disclosed in U.S. Pat. Nos. 5,613,335 and
5,836,122, both to Rennich et al. These patents disclose a paper
bead (tape-on bead) utilizing a paper layer which is uniformly
impregnated throughout its thickness with latex or similar
strengthening compound with a high wet strength so as to make the
paper strip resistant to scuffing and abrasion throughout its
thickness. This impregnated stock paper would have a high pick
resistance or surface fiber bond, and would effectively inhibit the
separation of surface fibers during application on wallboard,
thereby providing a good finished appearance in installation.
However, the applicants herein have found that paper of this type,
which has been impregnated with latex or the like, exhibits poor
joint compound bonding properties. Bond Strength Test ASTM C 474 is
required by specifications ASTM C 475 and ASTM C 1047 for wallboard
accessories manufactured from steel and paper in combination. This
ASTM test observes the result of peeling the paper away from a
joint compound bond made under controlled conditions.
BRIEF SUMMARY OF THE INVENTION
[0013] It is therefore a general object of the present invention to
provide an improved tape-on corner bead with paper wings which
exhibits high bond strength.
[0014] Yet another object is to provide an improved tape-on corner
bead which will firmly bond to the drywall construction, the
supporting metal corner angle, as well as the joint cement applied
over the top thereof.
[0015] A further object of the present invention is to provide a
method for constructing tape-on corner bead which permits secure
attachment of the corner bead to wallboard.
[0016] These and other objects will be apparent to those skilled in
the art.
[0017] The corner bead of the present invention is of the tape-on
type, having an elongated metal core strip with a longitudinal
arcuate nose and a pair of flanges extending outwardly from the
nose. A cover strip of paper is bonded to the exterior surface of
the core strip, and includes wings which project outwardly beyond
the extent of the flanges. The cover strip is formed of a
non-latex-bearing stock paper having high abrasion resistance,
tensile strength, and which is dimensionally stable on contact with
wet joint compound.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0018] The preferred embodiment of the invention is illustrated in
the accompanying drawings, in which similar or corresponding parts
are identified with the same reference numeral throughout the
several views, and in which:
[0019] FIG. 1 is a perspective view of the corner bead of the
present invention exploded away from an exterior corner of
wallboard construction;
[0020] FIG. 2 is a perspective view of a corner of wallboard
construction with the corner bead of the present invention thereon,
and covered with joint cement for a finished surface; and
[0021] FIG. 3 is an enlarged top view of the corner bead mounted on
a corner of wallboard construction.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Referring now to the drawings, a corner bead of the present
invention is designated generally at 10 and includes an elongated
metal core strip 12 formed with a central arcuate longitudinal
channel forming a nose 14, with flanges 16 and 18 extending
outwardly from each edge of the channel of nose 14 at an
approximate right angle.
[0023] Core strip 12 is preferably a galvanized steel strip having
a thickness of approximately 0.014 inches which has been
roll-formed. In the preferred embodiment, the flanges are 3/4 of an
inch in length, measured from nose 14. The typical core strip nose
will have an outside radius of up to about 1.5 inches, and project
outwardly from the plane of the flanges approximately 0.033 inches,
to provide space to receive joint cement, to cover and "dress" the
corner.
[0024] In the method of assembly of the corner bead, a continuous
steel strip first passes through a preforming roll forming section.
The preforming section, by means of progressive contoured rolls,
forms the steel core strip 12 into a cross-section that begins to
conform to the desired finished shape of the corner bead. This
preformed steel strip then progresses into an assembly section.
[0025] A continuous length of paper strip enters a paper
conditioning section, wherein mechanical abrasion breaks some of
the surface bond of the paper fibers and simultaneously, by means
of a roller die, pierces a plurality of small apertures through
designated regions of the paper. In an alternative embodiment, the
surface of the paper is not abraded, but a plurality of apertures
are pierced through designated regions of the paper. The perforated
paper strip then progresses to the assembly section for attachment
to the preform core.
[0026] In the assembly section, the conditioned paper strip is
guided through a preheating section that brings the paper to a
suitable elevated temperature to improve the subsequent adhesive
bonding. It then passes against a slot type hot melt adhesive
applicator head, which applies a stripe of adhesive to the paper.
The design of the slot head, along with control over the relative
travel speed of the paper strip and the rate of flow of adhesive,
regulate the location, width and thickness of the adhesive stripe.
The heated paper strip with adhesive thereon is then guided into
contact with the steel core preform. The assembly of steel core
preform, adhesive and paper strip then progresses into a finish
forming section.
[0027] In the finish forming section, the assembly passes through a
second series of contoured forming rolls. These rolls form the
assembly into the desired finished cross-section shape of the
corner bead, and simultaneously provides the necessary pressure to
achieve the bond between the paper strip 20 and steel core strip
12. The bonded and formed corner bead then progresses to a cut off
section where the corner bead 10 is sheared into the desired
finished length.
[0028] The selection of the paper of paper strip 20 is critical to
the invention. Conventional joint tape paper has low pick
resistance, which results in good bond strength with joint
compound, but produces a product that is difficult to finish. The
scraping and sanding that occur in drywall finishing will separate
the surface fibers of the paper, resulting in balling and/or
protruding fibers and a resulting poor finished appearance.
[0029] A stock paper impregnated with latex, or other strengthening
compound, to a relatively uniform concentration through its
thickness would have a high pick resistance or surface fiber bond.
Thus, the impregnated paper would effectively inhibit the
separation of surface fibers during drywall application, and would
provide a good finished appearance in installation. This type of
paper is described in U.S. Pat. Nos. 5,613,335 and 5,836,122,
described above. However, the inventors' own tests on such paper
have found that the paper did not have the desired performance in
resisting peeling.
[0030] Another particular type of paper which was tested was
wallpaper stock (or hanging stock). This type of paper is
impregnated from one side with a polymer intended to make the paper
printable and scuff resistant, while the opposite side of the paper
remains highly bondable. While these are highly desirable
properties, the wallpaper stock is not suitable because of a lack
of dimensional stability. The paper expands considerably on
exposure to moisture, which causes a buckled appearance when
imbedded in joint compound.
[0031] The preferred paper stock therefore must have a high pick
resistance, high tensile strength, and be dimensionally stable on
contact with wet joint compound. The inventors herein have found
that a paper produced by E. B. Eddy's (Domtar) brand code 5520/150
GSM Sand Back meets all of these requirements. This paper is
produced without the impregnation or coating of latex or other
strengthening compound, and was designed for use as a sandpaper
backing stock. Tests have been conducted both with plain white
paper, as well as colored samples, utilizing the method of assembly
as described above. Thus, the use of a non-impregnated, non-coated
paper on a corner bead can produce a corner bead with a higher peel
bond strength when installed on wallboard.
[0032] As shown in the drawings, the preferred embodiment of the
invention utilizes a paper cover strip 20 with wings 22 and 24
affixed to flanges 16 and 18 respectively, and extending beyond
flanges 16 and 18. The paper preferably has a thickness of
approximately 0.007 inches and will project beyond flanges 16 and
18 approximately 5/8 of an inch. A plurality of very small diameter
holes, preferably 0.005 to 0.02 inches in diameter are punched
through the cover strip to assist in adhering the paper strip to
the wallboard 26, the core strip 12, and joint cement 28 applied to
the exterior surface thereof. The inventors have found that paper
with an off-white tint is preferable, so as to match the color of
the drywall facing paper and joint cement. In this way, if a
portion of the joint cement is sanded away to reveal the paper
strip, the color of the paper strip will closely match the color of
the wallboard and will not reveal any stark contrasts.
[0033] The corner bead 10 is applied in the conventional manner for
tape-on beads. Once the joint cement covering the cover strip 20
from nose 14 outwardly over wings 22 and 24, has dried, the joint
cement is sanded.
[0034] Whereas the invention has been shown and described in
connection with the preferred embodiment thereof, many
modifications, substitutions and additions may be made which are
within the intended broad scope of the appended claims. More
specifically, this invention may be applied to all varieties of
drywall accessory or trim, including those types described in ASTM
C 1047.
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