U.S. patent application number 13/920854 was filed with the patent office on 2013-10-31 for method of making molded fiberboard panels and products fabricated from the panels.
The applicant listed for this patent is Noble Environmental Technologies Corp.. Invention is credited to Robert Noble.
Application Number | 20130284357 13/920854 |
Document ID | / |
Family ID | 41114798 |
Filed Date | 2013-10-31 |
United States Patent
Application |
20130284357 |
Kind Code |
A1 |
Noble; Robert |
October 31, 2013 |
METHOD OF MAKING MOLDED FIBERBOARD PANELS AND PRODUCTS FABRICATED
FROM THE PANELS
Abstract
A honeycomb-shaped panel is formed from a plurality of generally
sinusoidally shaped strips of molded fiberboard material each
having spaced, oppositely directed flat peaks, the peaks of
adjacent strips being secured together to form a plurality of
hexagonally shaped cells extending perpendicular to the surfaces of
the sheet. The strips may be cut from a single sheet of corrugated
fiberboard sheet material and then secured together to form the
honeycomb panel, or a plurality of such panels may be secured
together face to face with their ribs aligned to form a stack, and
selected cuts may be made through the secured, stacked panels to
form a plurality of honeycomb panels of desired surface shape and
height dimensions.
Inventors: |
Noble; Robert; (Encinitas,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Noble Environmental Technologies Corp. |
San Diego |
CA |
US |
|
|
Family ID: |
41114798 |
Appl. No.: |
13/920854 |
Filed: |
June 18, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12412780 |
Mar 27, 2009 |
8475894 |
|
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13920854 |
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61040596 |
Mar 28, 2008 |
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Current U.S.
Class: |
156/256 ;
156/250 |
Current CPC
Class: |
B32B 21/02 20130101;
B32B 2307/72 20130101; B32B 2307/50 20130101; B32B 2307/718
20130101; B32B 5/022 20130101; D21J 1/16 20130101; Y10T 156/1052
20150115; Y10T 428/24314 20150115; B32B 3/00 20130101; B32B 21/13
20130101; Y10T 428/24149 20150115; Y10T 428/1348 20150115; B32B
2307/546 20130101; Y10T 156/1075 20150115; B32B 21/10 20130101;
B32B 2262/062 20130101; E04C 2/322 20130101; E04F 2203/04 20130101;
E04C 2/3405 20130101; Y10T 428/236 20150115; A47C 5/005 20130101;
B32B 3/10 20130101; B32B 2262/14 20130101; E04F 13/16 20130101;
B32B 3/12 20130101; D21J 1/04 20130101; E04F 2203/08 20130101; Y10T
156/1062 20150115; B27H 1/00 20130101; B32B 7/05 20190101; E04C
2/16 20130101; Y10T 428/1303 20150115; Y10T 428/24083 20150115;
B32B 38/0004 20130101; E04C 2002/3455 20130101; Y10T 428/24694
20150115; B32B 3/28 20130101; B27F 1/00 20130101; E04C 2/365
20130101; B32B 2419/00 20130101; B32B 5/22 20130101; Y10T 428/24165
20150115; B32B 5/26 20130101; B27N 5/00 20130101 |
Class at
Publication: |
156/256 ;
156/250 |
International
Class: |
B32B 3/12 20060101
B32B003/12; B32B 38/00 20060101 B32B038/00 |
Goverment Interests
GOVERNMENT LICENSE RIGHTS
[0002] The U.S. Government has a paid-up, royalty-free,
nonexclusive, nontransferable, irrevocable license in this
invention and the right in limited circumstances to require the
patent owner to license others on reasonable terms due to joint
ownership of the invention and as provided for by the terms of
CRADA (Cooperative Research and Development Agreement) No.
07-RD-11111124-027 awarded by the USDA, Forest Service.
Claims
1. A method of forming a fiberboard panel, comprising the steps of:
making a series of spaced cuts at least one sheet of molded,
corrugated fiberboard material having a plurality of alternating
ribs and grooves, the cuts extending transversely across the sheet
to form a plurality of wave-shaped strips having opposite cut edges
and alternating flat peaks on opposite faces connected by inclined
webs; positioning the strips side-by-side with the flat peaks of
adjacent strips aligned face-to-face and oriented parallel to one
another, whereby the strips together form a generally honeycomb
shaped array; and adhering the opposing flat peaks of the adjacent
cells together to form a honeycomb-shaped sheet having a plurality
of hexagonal cells.
2. The method of claim 1, wherein at least one cut edge of each
strip is cut in a direction non-parallel to the opposite cut edge
of the strip, whereby the sheet formed from the strips has at least
one non-flat face.
3. The method of claim 2, wherein the strip edges are cut such that
the sheet has one curved face.
4. The method of claim 2, wherein the strip edges are cut such that
the sheet has opposite curved faces.
5. The method of claim 1, wherein the strip edges are cut such that
the sheet has one faceted face.
6. The method of claim 1, wherein the strip edges are cut such that
the sheet has one angled face and is generally triangular in
cross-section.
7. The method of claim 1, further comprising securing first and
second outer layers of flexible flat fiberboard sheet material over
the first and second faces of the sheet.
8. A method of forming a fiberboard panel, comprising the steps of:
positioning a plurality of molded corrugated fiberboard sheets face
to face to form a stack of sheets, each sheet having opposite faces
each having a plurality of alternating, longitudinally extending
ribs and grooves extending along the length of the sheet, the ribs
on the first face each having a first peak and the ribs on the
second face each having a second peak facing in the opposite
direction to the first peaks; aligning the peaks on opposing faces
of each pair of adjacent sheets in the stack; adhering the aligned
peaks of each pair of adjacent sheets together to form a plurality
of generally hexagonal cells extending along the length of the
stacked sheets; and cutting generally transversely through the
stack at a plurality of selected spaced locations along the length
of the stack to form a plurality of separate, honeycomb shaped
panels.
9. The method of claim 8, wherein the cuts through the stack are
parallel to one another.
10. The method of claim 8, wherein at least one cut through the
stack is in a non-straight direction, whereby the panel face formed
by said one cut is a non flat face.
11. The method of claim 10 wherein said one cut is curved and the
non-flat panel face is curved.
12. The method of claim 10, wherein at least two adjacent cuts
through the stack are curved and the panel formed between the
adjacent curved cuts has opposing curved faces.
13. The method of claim 8, wherein said one cut forms a faceted
panel face.
14. The method of claim 8, wherein said one cut is at an angle to
the longitudinal direction of the stack and an adjacent cut is
perpendicular to the longitudinal direction, whereby a panel formed
by said adjacent cuts has a first flat face and a second angled
face.
15. The method of claim 8, further comprising securing first and
second outer layers of flexible flat fiberboard sheet material over
opposite faces of the honeycomb-shaped panel.
Description
RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. patent
application Ser. No. 12/412,780 filed on Mar. 27, 2009, which
claims the benefit of co-pending U.S. provisional patent
application No. 61/040,596 filed Mar. 28, 2008, and the contents of
each of the aforementioned applications are incorporated herein by
reference in their entirety.
BACKGROUND
[0003] 1. Field of the Invention
[0004] This invention relates generally to engineered,
pressure-molded fiberboard panels with applications in
manufacturing, building construction, packaging, and other fields,
and is particularly concerned with methods of making such
panels.
[0005] 2. Related Art
[0006] "Dry-process" wood-product panels such as medium density
fiberboard (MDF), particleboard (PB), and oriented strandboard
(OSB) are known in the construction field. These products are
largely manufactured by combining wood cellulose with
formaldehyde-based resins and other bonding materials to form rigid
panels. These panels are generally relatively heavy and not
particularly flexible, and they are prone to toxic off-gassing
caused by the resins used in manufacturing.
[0007] "Wet-process" panels are also known in the field. A
"wet-process" panel is made by wet forming, i.e. panel materials
and water are processed to form a slurry which is then poured over
a form, and water is then removed by vacuum or the like. Known
"wet-process" panels include mostly low-density cardboards,
composite panel products, and agricultural fiberboards.
SUMMARY
[0008] In one embodiment, a method of forming a fiberboard panel
comprises the steps of: positioning a plurality of molded
corrugated fiberboard sheets face to face to form a stack of
sheets, each sheet having opposite faces each having a plurality of
alternating, longitudinally extending ribs and grooves extending
along the length of the sheet, the ribs on the first face each
having a first peak and the ribs on the second face each having a
second peak facing in the opposite direction to the first peaks;
aligning the peaks on opposing faces of each pair of adjacent
sheets in the stack; adhering the aligned peaks of each pair of
adjacent sheets together to form a plurality of generally hexagonal
cells extending along the length of the stacked sheets; and cutting
generally transversely through the stack at a plurality of selected
spaced locations along the length of the stack to form a plurality
of separate, honeycomb shaped panels.
[0009] The cuts through the stack may be parallel to one another,
or one cut may be non-parallel to the other cut, for example at an
angle. In other embodiments, one or both cuts may be curved or one
cut may be faceted. Outer layers of fiberboard sheet material may
be secured over opposite faces of the honeycomb shaped panel.
[0010] The corrugated sheet and flat sheets (if used) for forming
the panel may be made from cellulose fibers such as bovine
processed fiber (BPF), recycled fiber such as old corrugated
cardboard (OCC) and old newsprint (ONP), wood fiber, agro-fiber, or
combinations thereof, using wet processing. Through continuous
hot-pressing of lignocellulosic fiber between mold elements, flat
and three-dimensional panels can be molded into a specially
engineered form. Continuous hot-pressing produces strong
inter-fiber bonds, even using relatively low-quality fiber. Panels
can be pressed flat, or a corrugated mold can be used to create
longitudinal ridges. When a honeycomb structural core is bonded to
flat-panel exterior skins, a lightweight, three-dimensional
stressed-skin panel is formed that exhibits a high level of
strength and stiffness.
[0011] The panel material may made from a wide range of cellulose
fiber sources, including wood and plant fibers, agricultural
biomass, and recycled fiber many fiber types may be used to
manufacture the panels. In one embodiment, bovine processed fiber
(BPF) is used for the panel material. BPF is bovine waste (i.e.,
agricultural fiber that has been consumed and digested by cows)
that has been further processed using simple anaerobic digester
technology commonly found at many cattle and dairy farms. BPF may
be used by itself to make the panel, while in other embodiments it
is used in combination with other fiber sources such as old
corrugated cardboard (OCC) or old newspaper (ONP).
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The details of the present invention, both as to its
structure and operation, may be gleaned in part by study of the
accompanying drawings, in which like reference numerals refer to
like parts, and in which:
[0013] FIG. 1 is a perspective view of a corrugated fiberboard
panel according to a first embodiment;
[0014] FIG. 2 is a cross sectional view of the panel of FIG. 1;
[0015] FIG. 2A is an enlarged view of the circled area of the panel
of FIG. 2;
[0016] FIGS. 3A, 3B and 3C are views similar to FIG. 2A of a set of
corrugated panels having dimensions which increase incrementally
from one panel to the next;
[0017] FIG. 4 is a perspective view of a laminated, stressed skin
panel in which the corrugated panel of FIG. 1 is laminated between
two flat fiberboard panels;
[0018] FIG. 5 is an end view of part of a modified laminated panel
with two layers of corrugated panel as the core;
[0019] FIG. 6 is a perspective view of another embodiment of a
multi-layer panel using multiple flat sheets and corrugated
sheets;
[0020] FIG. 7 is a cross-sectional view illustrating the opposing
platens of a cold or hot press used in manufacturing the corrugated
fiberboard sheet of FIG. 1;
[0021] FIG. 8 is a cross-sectional view illustrating a cold or hot
press similar to FIG. 7 but with a modified upper platen;
[0022] FIG. 9 is a perspective view of one embodiment of a
honeycomb-shaped fiberboard panel manufactured from a corrugated
sheet as illustrated in FIG. 1;
[0023] FIG. 10 is a perspective view of two lengths of corrugated
sheet material turned through ninety degrees and placed face to
face with their ribs aligned;
[0024] FIG. 11 is a perspective view of a laminated, stressed skin
panel in which the honeycomb panel of FIG. 9 is laminated between
two flat fiberboard panels;
[0025] FIG. 12A is a perspective view of another embodiment of a
honeycomb panel with an upper curved surface;
[0026] FIG. 12B is a side elevation view of the honeycomb panel of
FIG. 12A;
[0027] FIG. 12C is an end elevation view of the honeycomb panel of
FIG. 12B;
[0028] FIG. 13A is a perspective view of another embodiment of a
honeycomb panel with an upper faceted face;
[0029] FIG. 13B is a side elevation view of the honeycomb panel of
FIG. 13A;
[0030] FIG. 13C is an end elevation view of the honeycomb panel of
FIG. 13B;
[0031] FIG. 14A is a perspective view of another embodiment of a
honeycomb panel having opposing curved faces;
[0032] FIG. 14B is a perspective view of a stressed skin panel with
the honeycomb panel of FIG. 14A as the core;
[0033] FIG. 14C is a side elevation view of the panel of FIG.
14A;
[0034] FIG. 15A is a perspective view of another embodiment of a
honeycomb sheet having an angled face with the flat face adhered to
a lower flat sheet;
[0035] FIG. 15B is a perspective view of a multi-ply panel in which
an upper flat sheet is secured over the upper angled face of the
honeycomb sheet of FIG. 15A;
[0036] FIG. 15C is a side elevation view of the panel of FIG.
15B;
[0037] FIG. 15D is an end elevation view of the panel of FIG.
15B;
[0038] FIG. 16 is a perspective view of a slotted panel formed with
spaced slotted portions of parallel slits;
[0039] FIG. 17 is a perspective view of another slotted panel
formed with slits at varying spacings;
[0040] FIG. 18 is a perspective view of another embodiment of a
slotted panel formed with diagonal slits;
[0041] FIG. 19 is a perspective view of another embodiment of a
corrugated panel formed with a radial slit configuration;
[0042] FIG. 20 is a perspective view of another embodiment of a
slotted panel with an alternating radial slit configuration;
[0043] FIG. 21 is a perspective view of part of a slotted panel
curved to form bends at the slotted portions;
[0044] FIG. 22 is a perspective view illustrating a panel with
alternating radial slits as in FIG. 20 with a bend formed at the
one of the radial slit locations;
[0045] FIG. 23 is a perspective view of a lower flat sheet and core
of another embodiment of a multi-layer fiberboard panel;
[0046] FIG. 24 is a perspective view of one embodiment of a curved
stressed skin panel using a corrugated sheet as the core;
[0047] FIG. 24A to 24D illustrate some alternative curved, stressed
skin panel shapes;
[0048] FIG. 25 is a perspective view of a second embodiment of a
curved stressed skin panel using a slotted corrugated sheet as the
core;
[0049] FIG. 26 is a side elevation view of the panel of FIG.
25;
[0050] FIG. 27 is a front perspective view of one embodiment of a
chair manufactured using a multi-radius curved panel;
[0051] FIG. 28A is a perspective view of one embodiment of a
tubular member formed from a corrugated sheet with slits to provide
increased flexibility;
[0052] FIG. 28B is a side elevation view of the tubular member of
FIG. 28A;
[0053] FIG. 28C is an end elevation view of the tubular member of
FIG. 28A and 28B; and
[0054] FIG. 28D is a perspective end view of the tubular member of
FIGS. 28A to 28C.
DETAILED DESCRIPTION
[0055] Certain embodiments as disclosed herein provide for
engineered molded fiberboard panels of various shapes and
configurations, as well as methods and apparatus for making such
panels, and products fabricated from such panels.
[0056] After reading this description it will become apparent to
one skilled in the art how to implement the invention in various
alternative embodiments and alternative applications. However,
although various embodiments of the present invention will be
described herein, it is understood that these embodiments are
presented by way of example only, and not limitation.
[0057] FIGS. 1 and 2 illustrate a corrugated fiberboard panel or
sheet 10 with alternating ribs 12, 14 on its opposite faces. The
panel is of molded fiber material and may be produced from a
variety of materials and raw material mixes (matrices) including
wood fiber, agro-fiber, including plant fibers and bovine processed
fiber (BPF), and post-consumer waste such as old corrugated
cardboard (OCC) and old newsprint (ONP). The panel may be
manufactured using a modified "wet-process", as described in more
detail below in connection with FIGS. 7 and 8. This process is
similar to the process used for making paper and traditional
fiberboard products, but without the addition of toxic resins or
binders commonly found in many competitive panel products,
especially those manufactured with older "dry-process" methods.
This is possible because, with carefully controlled heat and
pressure, the cellulose contained in a matrix of refined fibers
(e.g., 50% OCC & 50% BPF) will react to form a natural
thermosetting adhesive that gives strength and integrity to the
finished fiber panel. In one example, the panel was made from
around 50% BPF and 50% ONP. These materials are inexpensive but
were found to combine in forming a relatively high strength,
flexible panel or sheet. In some cases, depending on the
application, the panel may be treated with fire retardant or other
additives.
[0058] As illustrated in FIGS. 2 and 2A, each rib 12, 14 has a flat
outer flange or peak 15, and adjacent, oppositely directed peaks
are connected by inclined webs 16. It has been found that an angle
of around 45 degrees for the webs 16 makes it easier to standardize
different panel dimensions for combinations of panels with each
other and with other building materials, although other angles may
be used in alternative embodiments. Additionally, a constant
rib-to-rib center spacing for different dimension panels makes it
easier to laminate or combine different panels to produce different
three dimensional panel arrangements and to make the panels
compatible with other standard construction material dimensions. In
one embodiment, a four inch center to center spacing between
adjacent peaks or flanges 15 is provided. If such a panel is
arranged vertically in a wall behind a wall board or the like, the
outermost rib flanges are at a four-inch spacing and can be easily
located for attachment of fasteners or the like. The flanges 15 are
positioned at the opposing, outer faces of the panel 10 and provide
a planar area to adhere or fasten to facing material, such as the
skin of a stressed skin panel 20 as illustrated in FIG. 4. The
flanges perform a similar function to the flange of a wide flange
"I" cross section structural member. The 45 degree angle of the
webs 16 allows for consistency in joining two such panels together
as a "mitre" to accomplish a ninety degree change in direction, for
example as illustrated in the panel described below in connection
with FIG. 5.
[0059] The panel 10 may be made in a variety of different
cross-sectional dimensions, panel thicknesses, flange dimensions,
web dimensions, and rib cross section shapes. In one embodiment,
the different panels are all calibrated to increments of 1/4 inch,
1/2 inch, 3/4 inch, 1 inch, or the like. This facilitates
compatibility with building industry standards and makes measuring
and locating internal flanges easier and faster for fastening.
Also, for a basic 1.5'' high panel, with 1/2'' flanges, the flanges
are exactly 4'' on center (oc) which facilitates compatibility as
above. FIGS. 2 and 2A illustrate a corrugated or ribbed cross
section panel 10 which has a height of about one inch, a peak width
of around 0.5 to 0.6 inches, a web angle of 45 degrees, and a panel
thickness of around 0.1 inches. The peak center to center spacing
may be in the range from 3 inches to 6 inches. This spacing may be
made constant for at least some different panel dimensions and rib
cross sections, to facilitate combinations of different dimension
panels.
[0060] FIGS. 3A, 3B and 3C illustrate a set of three panels 20, 22,
and 24 of incrementally increasing height (0.75 inches, 1.5 inches,
3 inches). The web angles of panels 20 and 22 are both 45 degrees,
like panel 10 of FIGS. 1 and 2. In one embodiment, panel 20 has a
repeated pattern design of 3/4 inch height, 3 inch center to center
width, 96 inch length and 45 degree angle, with a thickness of 0.1
inch. Panel 22 has a repeated pattern design of 1.5 inch height, 6
inch center to center width, 45 degree angle of webs, thickness of
0.1 inch, and 96 inch length. Panel 24 has a repeated pattern
design of 3 inch height, 6 inch center to center width, a 60 degree
web angle, 0.1 inch thickness, and 96 inch length. The panels have
peaks 15A, 15B and 15C, respectively, and angled flanges 16A, 16B,
and 16C, respectively, extending between each pair of oppositely
directed peaks. Dimensions and angles may be determined for product
performance when used in furniture, construction and other
applications.
[0061] FIG. 4 illustrates one embodiment of a composite,
stressed-skin panel 30 which is made by sandwiching a corrugated,
ribbed panel such as panel 10 between two flat panels or skins 32
which are made from the same fiber material as panel 10 using the
same manufacturing process. This creates a stressed-skin panel with
a very high strength to weight ratio. The corrugated and flat
panels 10, 32 are flexible prior to being adhered together, but
once laminated they form lightweight stressed-skin panels or
structural panels with high strength, while still exhibiting some
flexibility.
[0062] FIG. 5 illustrates a second embodiment of a composite
stressed-skin panel 40. Panel 40 comprises a pair of corrugated
panels 10 which are stacked one on top of the other with the inner
rib peaks 15 aligned and adhered together, and which are then
sandwiched between two flat panels or skins 32. The outer flat
panels 32 are suitably adhered to the outermost flat peaks 15 of
the respective panels 10. This creates a very strong and rigid
panel. Since the angled webs 16 of the two corrugated panels 10 are
each at 45 degrees, this creates a 90 degree change in direction
(see Angle "a" in FIG. 5, for example). It also creates channels
42, 44 of different sizes which can be used for air distribution
and as a pathway for conduit, pipes, building wiring, or the like
through the panel.
[0063] FIG. 6 illustrates a third embodiment of a multi-layer,
stressed-skin panel 45. This panel uses the three layer panel 40 of
FIG. 5 as the core. A first outer corrugated sheet 10A is adhered
to one of the outer panels 32 of core 40 with its ribs extending
perpendicular to the ribs of the two central ribbed sheets 10 of
the core. A second outer corrugated sheet 10B is adhered to the
other outer panel 32 of core 40. Finally, two outer flat sheets or
skins 47 are adhered to the outer faces of corrugated sheets 10A
and 10B. The multi-layer panel thus has four core layers of
corrugated sheet material, with the ribs of the two central layers
extending in a first direction and the ribs of the two outer
corrugated layers 10A and 10B extending transverse to the first
direction. In one embodiment, the ribs of the central layers are
arranged to be oriented horizontally if the panel 45 is used as a
vertical construction or wall panel, with the ribs of the outer
corrugated layers extending vertically.
[0064] The multi-layer panel 45 has plural passageways 49 extending
through the center section in a first direction, as well as plural
passageways 51 which extend transverse to passageways 49 in each
outer section. This arrangement allows for horizontal distribution
of air or conduit, pipes, wiring and the like along each panel and
continuing through to the next panel. It provides an integral mini
duct/conduit guide configuration. Some of the horizontal
passageways can be used for air distribution, with others used as a
pathway for wiring pipes, cables, and/or conduit. The vertical
outside channels or passageways 51 allow for insulation and/or
reinforcing material to be cast into the outer layers of the panel.
Reinforcing materials such as concrete with metal or fiberglass
tension resistant components may be used for this purpose,
producing a highly efficient configuration placing the high
strength materials out along the face away from the central axis,
oriented vertically for improved buckling, uplift and compression
resistance of the wall assembly.
[0065] Panel 45 is of low cost due to use of simple corrugated
components with alternating orientation providing a high strength,
low weight basic configuration. Additional weight such as
additional layers may be added for strength if needed. The panel is
of simple construction and allows for various attachment
methods.
[0066] The corrugated fiberboard sheets and composite panels of
FIGS. 1 to 6 have improved structural integrity and may be up to 4
times stronger than other panels of similar weight such as foam
boards or paper honeycomb products. At the same time, the panels
are lightweight, and may be as little as 25% of the weight of
conventional panels engineered to the same bending strength, such
as particleboard, plywood, medium density fiberboard (MDF) or
oriented strand board (OSB). The panels are all light and durable
panels, and are therefore easy to lift and transport. The light
weight of the panels also results in reduced shipping and
installation costs, and reduced injury and liability exposure in
factory locations and on construction sites. The absence of
chemicals and toxins in production process also makes the panels
safer and gives rise to fewer regulatory issues due to non-toxic
production process. The panels can be self supporting soffets and
valances without the need for an elaborate secondary structural
frame
[0067] In one embodiment, the ribbed panels and flat panels
described above are made by a process which involves:
[0068] 1. Mechanical, chemical or other digestion of selected fiber
or fibers into a "furnish."
[0069] 2. Hydro pulping of the digested furnish (introducing into a
water solution and mixing to separate all fibers into a
"pulp").
[0070] 3. Introduction of the pulp into the former (or deckle) box
which has the perforated "mold screen" at its bottom. The mold
screen has a cross section almost identical with the desired cross
section of the finished panel, i.e., a ribbed or corrugated section
when making the panels of FIGS. 1 to 3, or a flat section when
making flat panels or skins 32.
[0071] 4. Most of the water is removed through the perforated mold
screen by a vacuum pulled from below. The remaining fiber mat has
significantly even distribution of fibers with respect to thickness
and fiber direction.
[0072] 5. The walls of the former box are lifted, like a sleeve, up
from the perimeter edge of the mold screen, which is sitting on the
bottom structure of the former box.
[0073] 6. The mold screen with the wet fiber mat is then
transferred longitudinally into a cold press between the press's
top and bottom platens which have cross sections virtually
identical to the mold screen.
[0074] 7. The cold press opening is then closed and pressurized to
squeeze the water out of the wet mat on the mold screen. This water
removal assists in reducing the time and energy requirements in the
next step of hot pressing.
[0075] 8. After the platens are separated, the mold screen with wet
mat is then transferred into a hot press with top and bottom
platens similar in cross section to the cold press. The hot platens
then close on the cold-pressed wet mat on the mold screen.
Additional de-watering occurs by squeezing and by vaporization,
along with cellulose bonding.
[0076] 9. When the mat has been densified due to heat and pressure
and is virtually moisture free, the platens are separated and the
mold screen and finished panel is transferred out of the press.
[0077] 10. The finished panel is then separated from the mold
screen, and the mold screen is returned to the former box for the
next cycle.
[0078] 11. The finished panel may then be sent to post-production,
for cutting, adhering, laminating, or the like.
[0079] Both cold and hot press design may include a top perforated
screen attached to the top platen, or, a top screen may be placed
on the wet mat prior to entry into the cold press. The top screen
fixed to the upper platen of the cold press opening simplifies
production. In addition, an elastic, non porous material may be
used to increase dewatering and densification of the mat in the
cold press and hot press.
[0080] In the case that the top screen is not fixed to the top
platens, the top screen is transferred through both the cold and
hot press and be removed after hot pressing to be returned to the
former box exit transfer area to be placed on a wet mat on mold
screen exiting the former box.
[0081] The first stage of panel manufacturing (steps 1 and 2 above)
is a wet-forming process whereby cellulose fibers and water are
hydropulped to form slurry that is then poured over a form (step
3). In step 4, vacuum suction is applied to the bottom of the mold,
thus pulling the water through the mold, but leaving the fiber to
form into a flat or three-dimensional mat. When all the "free"
water is pulled through the mat, the residual moisture content is
about 80%. Additional cold pressing in steps 6 and 7 removes more
"free" water, leaving only a minimal amount of "free" water and the
saturated fibers. The formed mats are then placed in a hot press
until dry (step 8). In one embodiment, the hot press conditions
were 370 oF with continuous 200 psi pressure. The pressure profile
slowly increases from 0 psi until it reaches 200 psi. The final
target panel thickness is nominally 0.1 inch with a specific
gravity of 0.9 to 1.0.
[0082] FIG. 7 illustrates one arrangement of opposing upper and
lower platens 45, 46 in the cold and hot presses used in the
process described above to make a corrugated or ribbed panel. The
lower platen 46 comprises a bottom, perforated plate or mold 48 of
stainless steel or the like which has a corrugated shape
corresponding to the desired panel shape and dimensions, and a
perforated mold screen 50 of matching shape positioned on top of
plate 48. Screen 50 is used to carry the wet fiber mat 52 from the
former box into the cold press, and also to carry the mat 52 after
cold pressing from the lower plate of the cold press onto the lower
plate of the hot press, as described above. The upper platen 45 in
this embodiment comprises a single platen of non-perforated or
non-porous elastomeric material having a lower surface shaped to
substantially match the shape of the lower platen and the desired
panel. The material of top platen 45 may be silicone based. Use of
an elastomeric or rubber material for the top platen has been found
to increase compression in the hot and cold press, increasing
dewatering and densification of the mat. It also creates a smoother
top surface in the panel.
[0083] FIG. 8 illustrates an alternative arrangement of the hot or
cold press, in which the lower platen is identical to that of FIG.
7, but the elastomeric upper platen 45 is replaced with a rigid,
perforated upper platen or press plate 55 of the desired shape, and
a perforated top mold screen 56 fixed to the platen 55. In
alternative arrangements, the top mold screen 56 is not fixed to
the top platen in the hot or cold press. In this case, the top
screen is transferred from the cold press to the hot press and is
removed from the panel after hot pressing is complete to be
returned to the former box exit area for placing on a wet mat
carried on the lower mold screen when exiting the former box.
[0084] Using stainless steel molds, the above process may be used
to create corrugated, three-dimensional panels and flat sheets with
a nominal material thickness of 0.03''-0.33''. Corrugated panels
may have cross-sectional depth of from 0.5'' to 1.5'' and greater.
These products may be laminated together to create exceptionally
strong yet lightweight "stressed-skin" panels in various sizes and
dimensions, for example the panels illustrated in FIGS. 4 and 5
above. When laminated together, one corrugated panel sandwiched
between two flat panels forms a stressed-skin panel with a
3-dimensional geometric core that provides lateral stiffness and
support to the two exterior faces. The resulting panels are
lightweight and have high strength characteristics and design
flexibility. This strength-to-weight characteristic is a result of
the geometry of stressed-skin panels that, like an airplane wing,
depend not upon a solid core of material for bending integrity, but
upon the strength of the faces and integral ribs.
[0085] The wet forming process as described above for manufacturing
fiberboard panels may use almost any type of fiber, extracting and
incorporating cellulose from a host of organic and post-consumer
waste materials, including urban sources of post-consumer fiber
waste such as OCC and ONP, and rural sources of underutilized
agricultural fiber such as BPF and crop residues. These highly
sustainable fiber sources are much more widely distributed and more
readily available than virgin wood, or even waste wood fibers, and
can be utilized at much lower cost. This means that the panels may
be manufactured in many regions, using many fiber sources, under a
variety of conditions. In urban areas, the panels can utilize waste
paper, cardboard, newsprint and other post-consumer waste materials
that are plentiful in all cities and towns. In rural areas, an
abundance of agricultural fibers, including raw plant fibers and
bovine processed fiber (BPF) may be used as raw materials for the
panels. The panels may be made using unused cereal crop residues
such as wheat straw and rice straw, dedicated fiber crops (e.g.,
hemp, flax, kenaf). On cattle ranches and dairy farms, bovine waste
(manure) is greatly underutilized, except as fertilizer and
bedding. But with natural and mechanical digestion (via anaerobic
digester technology already in use at many farms), this natural
source of cellulose fiber may be used as a primary fiber source for
the panels described above. As an added benefit, the methane
produced as a natural byproduct of bovine fiber processing can be
used to generate heat and electricity to run the production line.
Water, another bi-product of dairy farm anaerobic digesters, can be
used for the wet production process as well, with most of the water
being reclaimed and recycled. These production enhancements may be
achieved with only slight modifications to existing technology. In
forested areas, the forest products industry has established
long-standing centers for building product raw material sourcing
and manufacturing. Many virgin fiber, as well as pre- and
post-consumer fiber sources of raw materials, are available in
forested areas in the northwest and southeast U.S., and elsewhere,
and such materials may also be used in panel manufacture.
[0086] In or near parks and managed forest lands, panels may be
manufactured from wood "waste" and undergrowth currently identified
as "fire hazard" material by USDA in its National Fire Plan (NFP)
for the reduction of fire hazards in the National, State, and
private forests. According to the USDA, many forest stands in the
Unites States are overcrowded and need to be thinned as part of
good forest management. In the view of the traditional forest
products industry, however, thinned forest materials are considered
economically non-viable--i.e., too small and/or containing too many
defects for structural lumber, and/or too costly to transport out
of the forest for most commercial purposes. As a result, these
underutilized wood fiber materials are often left on the forest
floor. In seasonally dry environments typical of the western U.S.,
this wood-waste buildup can become a significant wildfire hazard,
as recent history has shown, threatening not only old-growth trees
and virgin timber, but also commercial and residential structures
in the vicinity. The manufacturing process described above may
provide an economically viable means to utilize this potentially
dangerous forest material on a commercial scale while supporting
public policy initiatives to reduce forest fire hazards and improve
forest management.
[0087] In tropical and other regions (with or without crops, farms,
or forests), prairie, tropical and other grasses, along with other
waste or underutilized fibers, may be used to manufacture the
panels. Prairie, tropical and other grasses are abundant throughout
the world, and they are known to contain excellent cellulose fiber
for wet process engineered molded fiber panel production. Although
not yet utilized to the extent of wood-based fiber sources,
sufficient research has shown the viability of these raw materials
from all over the world. The ubiquity and diversity of possible raw
material sources allows for potential panel production sites in the
vicinity of each fiber source, potentially cutting down
transportation and delivery distances to market, thereby reducing
costs for bringing the panels and products made from the panels
from factory to end-user. In addition, panel production near end
users results in lower fuel consumptions and less pollution related
to the transport/distribution process. Reduced weight of the final
product (as low as 25% of traditional wood-fiber panels and
materials) also significantly reduces the cost of shipping and
delivery. In sum, the energy and labor efficiencies (along with the
attendant environmental benefits) of producing lighter,
significantly less toxic, easier to handle products nearer to the
final market are abundant.
[0088] Although various different fiber sources for manufacturing
the panels of FIGS. 1 to 6 have been described above, some improved
panel properties have been found when combinations of two different
fiber types with different properties are used. In one embodiment,
a mixture of approximately 50% BPF and 50% ONP was found to have
improved cellulose bonding and strength properties and result in
more uniform densification due to the different fiber types.
[0089] FIG. 9 illustrates one embodiment of a honeycomb-shaped
panel 100 of molded fiberboard, the panel comprising a plurality of
repeating, hexagonal cells 112 with webs 114 which are generally
perpendicular to the plane of the panel. In one embodiment, the
panel is of molded fiber material and may be produced from a
variety of materials and raw material mixes (matrices) including
wood fiber, agro-fiber, including plant fibers and bovine processed
fiber (BPF), and post-consumer waste such as old corrugated
cardboard (OCC) and old newsprint (ONP). Although the webs 114 are
perpendicular to the plane of the panel in FIG. 1, they may be at
other angles relative to the plane of panel 100 in alternative
embodiments.
[0090] The panel 100 may be manufactured from corrugated sheets 10
of molded fiberboard material as illustrated in FIG. 1 which have
alternating ribs and grooves forming the corrugated shape. In order
to make a honeycomb-shaped panel, two such sheets, or two cut
lengths or strips of sheet 10, are turned through 90 degrees from
the position of FIG. 1 and placed face to face with their ribs
aligned as in FIG. 10, and the abutting flat peaks or flanges 15 of
the ribs are secured together with a suitable adhesive. This
process is then repeated with additional lengths or strips of the
corrugated sheet, or additional sheets 10, until the desired panel
length is achieved. When plural corrugated sheets are secured
together in the manner illustrated in FIG. 10, the assembled panel
can be cut to a desired height, for example along dotted line 126
of FIG. 10. If one or both panel faces are to be non-straight, the
assembled panel structure can be cut along a suitably shaped line,
such as curved line 127 of FIG. 10, to provide the desired surface
contour to the honeycomb panel. In an alternative method, a
corrugated sheet 10 as in FIG. 1 is cut into a plurality of short
strips of height corresponding to the desired panel height, for
example along dotted lines 128 of FIG. 1, and the strips are then
turned into the orientation of FIG. 10 and placed face to face with
their opposing rib peaks 15 abutting and adhered together.
Versatility of shape, thickness and strength of the honeycomb panel
100 may be achieved by suitable variation of the strip width and
shape. The thickness and cross-sectional dimensions of the
corrugated panel 10 used to form the honeycomb panel 100 may also
be varied according to the desired panel performance and design
parameters. Variable finished honeycomb panel depth, shape, and
other characteristics may be achieved by varying the parameters of
the source corrugated panel 10, by changing the width or shape of
the cut strips forming the panel, or by shaping the panel after the
strips or lengths of panel are adhered, as indicated in FIG.
10.
[0091] The honeycomb panel 100 of FIG. 9 is significantly more
rigid in a direction perpendicular to the panel than a
corresponding cardboard, accordion-like honeycomb sheet. Cardboard
honeycomb is also collapsible inwardly into a flat configuration.
In contrast, the webs forming the cells of panel 100 are relatively
rigid and cannot be collapsed inwardly. Thus, panel 100 tends to
hold its formed peripheral shape. However, depending on the
selected panel thickness or height, the panel 100 may be flexed or
curved to form different curved shapes, for example when forming a
curved, multi-ply panel as described below in connection with FIGS.
24 to 26, or any of the products described below in connection with
FIGS. 27 and 28. Alternatively, the panel 100 can be cut into any
desired shape before laminating between opposing skins or flat
sheets, as described below in connection with FIGS. 11 to 15.
[0092] FIG. 11 illustrates one embodiment of a composite,
stressed-skin panel 130 which is made by sandwiching a honeycomb
panel such as panel 100 of FIG. 9 between two flat panels or skins
132 which are made from the same fiber material as panel 100, using
a modified wet-forming process as discussed above. This creates a
stressed-skin panel with a very high strength to weight ratio. The
honeycomb and flat panels 100, 132 are flexible prior to being
adhered together, but once laminated they form lightweight
stressed-skin panels or structural panels with high strength, while
still exhibiting some flexibility.
[0093] FIGS. 12A to 12C illustrate a modified honeycomb panel 140
with a curved upper surface 142. The panel 140 may be laminated
between two flexible panels or skins 144 as illustrated in the
upper part of the drawing, or may be a stand-alone honeycomb panel
or core. Panel 140 may be formed as described above, for example by
adhering together several lengths of corrugated sheet fiberboard
material in the orientation of FIG. 10 and then cutting across the
assembled sheets to form the desired opposing panel surfaces. In
this case, one surface of the panel is flat and the other is
curved, but opposing curved surfaces may be formed if desired, and
other curved surface shapes with multiple curves, variable radius
curves, compound curves or the like may also be formed.
[0094] Honeycomb panels may also be formed with one or both
surfaces being angled, faceted surfaces, by appropriate cutting of
upright strips or lengths of corrugated sheet material which have
been adhered together at the abutting rib peaks. FIGS. 13A to 13C
illustrate one embodiment of a honeycomb panel 145 with a faceted
upper face 146. The lower part of FIG. 13A illustrates the
honeycomb panel alone with a cut upper faceted face 146, while the
upper part of FIG. 13A and FIGS. 13B and 13C illustrate a flexible
panel or skin 148 laminated on the upper face. A lower flexible
panel or skin may also be laminated on the lower face of panel
145.
[0095] FIG. 14A illustrates another embodiment of a honeycomb panel
150 which has curved upper and lower faces 152, while FIG. 14B
illustrates a multi-layer panel comprising the panel or sheet 150
laminated inside an outer flexible panel or skin 153 or two
flexible flat panels or skins which flex to adopt the desired
curvatures.
[0096] FIG. 15A illustrates another embodiment of a honeycomb sheet
154 which has a flat lower face 155 and an angled upper face 156.
FIG. 15A illustrates the lower flat face of sheet 154 adhered to a
flexible flat panel or sheet 157. Panel 154 may be laminated
between two flexible flat panels or sheets 157 to form a
multi-layer panel 159, as illustrated in FIGS. 15B to 15D.
[0097] The corrugated or ribbed sheets of FIG. 1 may be cut with a
number of slits across the ribs of the corrugated panel in various
ways, allowing the panel to be bent into a curve for use as a
stand-alone product or as a core component of a sandwich stressed
skin panel. Some alternative slit configurations are illustrated in
FIGS. 16 to 21, while FIGS. 22 and 23 illustrate how curves or
bends may be formed at the slotted panel regions. The slits are cut
across the ribs from one face of the panel, terminating short of
the peaks or flanges of the ribs on the opposing face, or may be
cut alternately from one face and the opposite face in some cases.
The slits may extend across the entire width or only part of the
panel width. The panel 60 in FIG. 16 has a plurality of spaced
slotted regions 62 each having a series of spaced slits 64
extending perpendicular to the rib direction. Slits 64 extend
through the uppermost webs 15 and side webs 16 in the illustrated
orientation, but terminate short of the lowermost webs 15. Instead
of spaced slotted regions as in FIG. 16, slits may be provided
along the entire length of the panel. Slotted regions may also be
provided alternately on opposite faces of the panel, for example
regions 62 as in FIG. 16 cut through the uppermost ribs as seen in
this drawing, with opposing slotted regions in the gaps between
regions 62 cut through the lowermost ribs and terminating short of
the peaks of the uppermost ribs. FIG. 17 illustrates another
embodiment of a slotted panel 65 which has slits 66 extending
perpendicular to the ribs and are arranged at variable spacings,
with alternating regions of closely spaced slits and widely spaced
slits.
[0098] The panel 68 of FIG. 18 has slits 69 extending diagonal to
the rib direction. Alternative versions of the panel 68 may have
staggered groups of diagonal slits, alternating diagonal slits on
opposite faces of the panel, or diagonal slits at variable
spacings, as in FIG. 17. The panel 70 of FIG. 19 has slits 72
extending radially. In FIG. 20, a panel 74 is provided with
alternating groups 75, 76 of radial slits 78, centered alternately
on opposite sides of the panel. FIG. 22 illustrates the panel 74 of
FIG. 20 with a bend or twist 90 formed at the location of the
radial slits, generally at the junction between the two groups 76
of radial slits.
[0099] In one embodiment, slits are cut using a saw across the ribs
of the corrugated panel from one face, not penetrating into the
flanges along the opposite outer face of the panel, allowing the
flanges along that outside plane to be continuous through the
resultant curve. The panel may then be curved with the slits on the
inside or the outside face of the curved panel. FIG. 21 illustrates
one embodiment in which a slotted panel 80 has spaced slotted
regions 82 and 84 which each have a series of perpendicular slits
85 and 86, respectively. The slits 85 are cut in the lower face as
viewed in FIG. 21, extending through the lowermost ribs and
terminating short of the peaks 15 of the uppermost ribs. The slits
86 are cut in the upper face and extend through the uppermost ribs,
terminating short of the peaks of the lowermost ribs. The panel 80
is bent or curved in opposite directions at the slotted regions 82
and 84 to form first bend 88 and second bend 89. In each case, the
slits 85 and 86 are positioned on the inside or concave part of the
curve. It is helpful to position the slits on the inside of the
curve due to the resultant limit when the slits close in towards
each other as the panel is curved. A mathematical formula with rib
height, slit width, on-center dimensions between slits determines
the resultant inside and outside radius "stop" of the curves. The
basic formula allows easy design to fabrication methods.
[0100] One version includes fixing the resultant curve with
adhesive when the corrugated panel with slits is bent/curved to its
automatic stop. The adhesive is applied between the slits at the
inside of the curve where the slit closes due to the curving.
Another version utilizes an additional strip of flat material with
a width similar to that of the flange which has been slitted. The
strip is adhered to the inside or outside face of the slitted
flange, fixing the curve.
[0101] Slits can be designed in a variety of configurations, some
of which are illustrated in FIGS. 16 to 22. These include
perpendicular continuous, perpendicular with variable spacing (FIG.
17), perpendicular staggered (FIG. 16), perpendicular alternating,
perpendicular alternating and staggered (FIG. 21), diagonal (FIG.
18), diagonal staggered, diagonal alternating, radial (FIG. 19),
radial alternating to opposite sides of the panel (FIGS. 20 and
22), radial alternating on opposite faces of the panel, radial
staggered, compound radial, variable on center slits to produce
compound, variable radius curves, and so on.
[0102] Panels with slits as in FIGS. 16 to 22 can be used as
stand-alone elements for interior design, containers, partitions
and screens, ceiling tiles, and formwork for plaster, concrete and
the like.
[0103] There are some benefits to making panels with curves using
slits to make the curved sections more flexible. First, there is
little or no "spring back" or "memory." Many methods of creating
curves include bending of veneers or sheets or panels into a shape
and fixing while setting. Such products typically spring back
somewhat in the direction of the original shape. Curved panels made
using slits as described above are stable in the finished shape
since they contain little or no residual memory stress when in the
set curved form. Curved, slotted rib panels may be stand alone or
may have curved flat panels or skins adhered to their outer faces.
This technique may be used to fabricate curves of multiple desired
radii, including custom and compound curves.
[0104] FIG. 23 illustrates a lower flat panel or sheet 200 and core
202 of another embodiment of a stressed skin panel. In this
embodiment, plural internal independent ribs are placed to provide
structural and strength to weight performance. An upper flat panel
or sheet (not illustrated) is placed over the upper surface of the
core and secured to the upper rib edges 204 in order to complete
the panel assembly.
[0105] In this embodiment, the ribbed or corrugated panel 100 of
FIG. 1 is cut into wave-like strips 205 of varying lengths and the
strips are placed or adhered in varying positions on the inside
face of the stressed skin panel 200 before adhering those strips to
the inner face of an upper stressed skin panel. The ribs are
generally perpendicular to the plane of the panel, although the
webs may be placed at an angle with respect to the plane of the
panel in alternative embodiments. Significant versatility of shape,
thickness and strength can be achieved by variation of strip width
and shape. In addition, by changing corrugated panel thickness and
material cross section dimension, the completed panel with the rib
core can achieve performance and design variations.
[0106] Since the ribs have a wave shape, they are stable and
resistant to collapse when placed freestanding on the first face of
the stressed skin panel, unlike a simple straight planar rib.
Variable finished product depth, shape and other characteristics
can be achieved by the using corrugated sheets 100 of varying
dimensions and cross-sectional shapes to make the ribs or strips
205, and by varying the width and shape of the strips. This
arrangement allows for flexibility in layout of the ribs, with a
greater number of ribs placed closer together in regions of the
panel requiring reinforcement to increase strength in those
regions. For example, in the arrangement of FIG. 23, a greater rib
density is provided in the edge regions 206 of the panel, with
fewer ribs in the central region. Different arrangements may be
provided to reinforce the panel at junctions. If the panel is
intended for use as a raised support surface on legs, additional
ribs are placed above the legs for added support.
[0107] Advantages of this new method of creating stressed skin
panels over other methods include: flexibility of layout, control
of position and structural design, applying material only where
needed, to provide improved strength to weight characteristics.
Such a panel can not be replicated by using paper or cardboard
honeycomb as ribs made from those materials are not structurally
adequate to provide the core strength, nor are they able to stand
on their own since they do not have a wave geometry. Uses of a
panel manufactured as indicated in FIG. 23 include furniture
finished product or core elements, packaging, containers, pallets
and the like, as well as interior partitions or screens, decorative
wall panels, core materials for planar stressed-skin panels or
complex forms and shapes used in furniture, art and construction
products or sub assemblies. Lounges, chairs, tables and other
furnishing may also utilize such panels, in addition to aerospace,
marine, rail and other transportation applications.
[0108] Panels made using a core as illustrated in FIG. 23 have
advantages over other light weight stressed skin panels in that
material can be placed easily only where needed to provide the
strength required, unlike honeycomb and other core materials which
are continuous and do not vary in strength along the length and
breadth of the core. This provides design flexibility to add
material only where it is needed thereby reducing weight for a
specified structural performance.
[0109] FIG. 24 illustrates one embodiment of a curved stressed skin
panel 210. Panel 210 comprises an inner core 212 of corrugated
sheet material 100 arranged with the ridges or ribs 15 running
perpendicular to the direction of curvature, and outer flexible
skins or sheets 214 laminated on opposite sides of the inner core
212. FIGS. 24A to 24D illustrate some examples of different curved
panel shapes and multi-ply panels which may be formed in a similar
manner. FIG. 24A illustrates a panel 211 having a simple curve.
FIG. 24B illustrates a panel 213 having a compound curve. FIG. 24C
illustrates a panel 217 having multiple plies or alternating layers
of flat flexible sheets and corrugated sheets. FIG. 24D illustrates
a curved panel 219 with alternating curves.
[0110] In an alternative embodiment, as illustrated in FIGS. 25 and
26, a curved stress skin panel 215 comprises a corrugated core
sheet 216 with slits 217 extending transversely across the ribs,
similar to the embodiments described above in connection with FIGS.
16 and 17, positioned between two outer flexible skins or sheets
218 and oriented with ridges 15 running parallel to the direction
of curvature. Using the corrugated panel, the material is sawed
down to the flange (or vice-versa from the flange outward) without
cutting all the way through. This cutting technique allows for both
concave and convex curves. Sheet 216 is oriented so that the slits
217 face inwardly into the curve (i.e. the sheet 216 is positioned
with its slotted face facing inward or on the convex side of the
curve), and tend to close at their inner ends 219, as best
illustrated in FIG. 25B. Using corrugated core to make curved
panels allows for more precision and the curves can be made on a
diagonal/radial/angular basis. This allows for much easier
adaptation for design requirements.
[0111] A curved, uniform thickness stressed skin panel may also be
made using a honeycomb core 100 as in FIG. 9 which is either bent
or trimmed/cut to the desired curved shape, with one or two skins
which may be pre-curved or made of bendable flat material. The
curves of any of the curved stressed skin panels may be single
radius, variable radius, or alternating radius. In alternative
embodiments, the curves may be multi-ply with two or more core
layers in the cross section.
[0112] Using the above techniques to make a curved panel means that
much less material is cut in order to make the curve. This process
is much easier to use since the core material, the corrugated or
honeycomb panel, is much lighter and easier to handle while
fabricating. The disadvantage of using other materials to curve
(particleboard, traditional MDF, plywood) is that the system used
to curve those panels ("kerfing") uses very heavy and thick
materials. Cutting these heavy and thick materials results in much
less precise cuts and flexibility while fabricating.
[0113] The curved panels of FIGS. 24 to 26 can be used in a large
variety of furniture, interior design, artistic wall panels, trade
show booths, stage sets, and other applications. This provides a
range of design capabilities for architects, interior designers,
furniture makers, and the like.
[0114] FIG. 27 illustrates a chair 240 formed from a length of
curved, three ply panel having a core of corrugated sheet 10,
honeycomb sheet 100, or slotted sheet with perpendicular slits
(FIG. 16 or 21). The chair 240 is formed over a rigid form or mold
in a shape matching that of the finished chair shape. A first layer
242 of flexible, flat fiberboard sheet is laid over the form and is
suitably cut and curved to follow the shape of the chair front legs
244, rear legs 245, back 246, and seat 248. A layer 250 of a
suitable core material is cut to shape and then curved over and
adhered to the upper surface of the first layer. Any of the panels
or cores described above in connection with FIGS. 1 to 5 and 9 to
22 may be used for the layer 250. If the core layer 250 is of
corrugated sheet material 10 of FIG. 1, it is laid with the ribs
running transverse to the chair curvature so that it can bend to
adopt the curved shape. If core layer 250 is a slotted sheet as
described above in connection with FIGS. 16 to 22, it is laid to
run along the length of the chair from back to seat to legs. In
this case, the slits may be cut appropriately at the locations of
curves 252, 254, and 255 so as to face inwardly relative to each
curve. In other words, in the region of curve 252 between the back
and seat portion of the chair, slits are formed through the upper
ribs of the sheet, while slits are formed through the lower ribs of
the sheet in the region of curve or bend 254. The core layer may
also be a layer of the honeycomb sheet 100. After the core layer
250 is adhered to the lower layer, an upper layer 256 of flat
fiberboard sheet is curved over and adhered to core layer 250.
[0115] Chair 240 is thus manufactured in a multi-radius curve from
one continuous piece of curved panel. The chairs 240 are readily
stackable for storage purposes. This method of making a chair from
a three ply cut and curved panel uses a minimal amount of material,
since only one 3 Ply panel is needed to make each chair, and this
technique provides many lightweight, artistic furniture options.
The material is also extremely lightweight, versatile for curving,
and strong. The chair may be formed with arms if desired, by
cutting additional strips at the outer edges to form the arms, for
example. Other curved chair designs may be made in a similar
manner, along with other types of furniture such as loungers,
benches, tables, and the like. The curved panel material is made
from three panels or sheets which are individually flexible so that
they can be bent readily to adopt any desired shape, but which are
fixed and rigid when assembled and adhered together, providing a
strong yet lightweight piece of furniture. The curved panel chair
of FIG. 27 has no spring back memory, unlike such shapes formed
from existing wood panel materials that tend to have some spring
back tendency after forming.
[0116] FIGS. 28A to 28D illustrate a cylindrical tube 260 formed
from corrugated, slotted fiberboard sheet cut with a plurality of
spaced, perpendicular slits 261 across the ribs, the slits
extending from one face (the innermost face of the formed bin)
towards the opposite face, terminating short of the flat flanges
262 which are on the outside of the formed bin. The slits are
evenly spaced along the length of the sheet in this case (i.e. as
in regions 62 of FIG. 16 but extending along the entire length of
the sheet with no interruptions). The slotted sheet is bent into a
cylinder with the slits 261 oriented vertically and facing into the
inside of the bin, so that they tend to close at their inner ends
263 on the inner flat flanges 264. The curved shape may be fixed
with adhesive between the inner ends of the slits. Additionally,
the abutting ends of the sheet may be secured together with a
suitable adhesive. Bands or strips of flat material (not
illustrated) with a width similar to that of the flat flanges or
ends 264 of the ribs may adhered around the outside face of each of
the outer grooves in the bin, i.e. over the flanges 264. The tube
has opposite open ends 265.
[0117] The cylindrical tube 260 may be used in many different
applications, such as formwork for spiraling columns; decorative
elements; an esthetic tubular lighting element; wall sconce;
concrete forms; and the like. In one embodiment, one open end of
the tube may be closed by a circular piece of flat panel material,
such as the rigid three ply panel of FIG. 4 or 11. The resultant
structure may be used as a waste bin or storage bin. Although the
tube 260 is cylindrical in the illustrated embodiment, it may be
made in many other possible shapes, such as triangular, circular
segment, and hexagonal shapes. Tubes may also be made in
rectangular or square shapes in a similar manner. For any angled
shapes, slits may be provided in the corrugated sheet just in the
regions where the angled bends are to be formed, rather than along
the entire sheet as in FIGS. 28A to 28D. Tube 260 may alternatively
be made from corrugated sheet without slits as in FIG. 1, with the
ribs running vertically along the tube, in any desired
cross-sectional shape. Tubes may also be made from the curved
panels of FIGS. 24 to 26 in alternative embodiments.
[0118] A tube may alternatively be made from a corrugated sheet 68
as in FIG. 18 with diagonal slits 69 at a 45 degree angle to the
rib direction. The diagonally slotted sheet is folded or bended
longitudinally to form a closed curve, with the edges suitably
secured together with adhesive, creating a long spiraling tube. The
sheet 68 may be wound spirally to form a tube in which the ribs
spiral along the length of the tube to create a decorative effect.
Adhesive may also be applied between the slits for added support.
Such a tube may also be used as formwork for spiraling columns;
decorative elements; an esthetic tubular lighting element; wall
sconce; concrete forms; and the like.
[0119] The sliced core sheet material makes it much easier to
create a consistent, complex geometrical shape for either esthetic
or functional uses. Currently existing panel materials do not lend
themselves to shaping and curving in this manner and have to be
combined with other materials to achieve such a shape. The tube 260
is an extremely lightweight, decorative and functional instrument.
Other options are simply too heavy, too thick, or too dense to
allow for such versatile applications
[0120] The engineered molded fiber panels described above provide a
family of high strength-to-weight, versatile component panel
products which may be combined in a range of light weight
structural panels with desirable surface features, consistency,
shape, pliability, versatility, strength and other performance
characteristics. Corrugated and honeycomb core panels can be used
by product manufacturers to create highly engineered and crafted
end products which require a relatively low level of embedded
material for required structural performance and thus are
relatively light weight. The panels may be nestled in a small
volume for shipping and storage, utilizing as little as 10% of the
volume required to ship and store commodity panel products.
Standard wood fabrication tools and techniques may be used in most
cases. Since conventional wood splintering does not occur with a
molded fiberboard panel, no gloves are required. The panel edges
may be fastened, edged, laminated and veneered as desired,
providing significant design fabrication and application
versatility. The corrugated or honeycomb shaped sheets and flat
panels or skins described above are flexible prior to being adhered
together. Once laminated they form lightweight stressed-skin panels
with relatively high strength, while maintaining some flexibility
characteristics. The panels may be formed into self supporting
soffets and valances without the need for an elaborate secondary
structural frame.
[0121] The panels described above are made from recovered resources
including waste paper and cardboard, wood residue, waste and
under-utilized agricultural fiber, thus turning low cost raw
materials into high quality panels. There is little or no toxic
off-gassing during fabrication or after installation as often found
in other panel materials. The manufacturing process is
environmentally friendly with the ability to utilize local recycled
and/or agricultural resources, creating the opportunity to site a
manufacturing plant virtually anywhere in the world. This process
also provides an alternative to virgin forest products, potentially
lessening the impact of global deforestation, preserving habitat,
encouraging sustainable business practices, and providing increased
markets for post-consumer fiber waste. Little or no pollution is
generated in the manufacturing process. The panel system is a very
flexible three-dimensional engineer-able system that has many
attractive performance characteristics. For example, the above
panels may be engineered to have the same approximate bending
stiffness as commercial grade particleboard (PB), but at
approximately 1/4 the weight.
[0122] The panel materials described above may be modified and
coatings may be applied to enhance the water resistant properties.
The panels also may be fire-retardant treated if used in
applications requiring high classification in building fire
performance.
[0123] To summarize, some of products' other unique features
include light weight, providing reduced shipping and handling
costs, decreased risk of workplace injuries and workers
compensation claims, and increased consumer mobility. The panels
utilize fiber selection, fiber processing, and 3D design to provide
an engineered system that reduces weight per performance needs. The
panels are also of high strength, providing increased product life,
decreased damage in shipping and handling, and versatility in a
number of product applications. They are also readily curvable, as
described above, providing quick, cost-effective structural curves
in custom and even compound radii, giving designers and
manufacturers tremendous fabrication flexibility and a broader
scope of possible market applications. The panels are relatively
easy and inexpensive to fabricate, providing the ability to cut,
fasten, laminate and edge using standard woodworking equipment and
industrial techniques. Products made with the panels are
eco-friendly, providing products with high recycled content, as
well as reduced or minimum off-gassing and toxicity. The panels can
be engineered from fibers to 3D geometry to final panel system to
provide high performance while significantly reducing or minimizing
total environmental impact. The panels can be made without resin,
or with formaldehyde-free resins.
[0124] The above description of the disclosed embodiments is
provided to enable any person skilled in the art to make or use the
invention. Various modifications to these embodiments will be
readily apparent to those skilled in the art, and the generic
principles described herein can be applied to other embodiments
without departing from the spirit or scope of the invention. Thus,
it is to be understood that the description and drawings presented
herein represent a presently preferred embodiment of the invention
and are therefore representative of the subject matter which is
broadly contemplated by the present invention. It is further
understood that the scope of the present invention fully
encompasses other embodiments that may become obvious to those
skilled in the art and that the scope of the present invention is
accordingly limited by nothing other than the appended claims.
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