U.S. patent application number 11/656627 was filed with the patent office on 2007-06-07 for multi-layered fire door and method for making the same.
This patent application is currently assigned to JELD-WEN, inc.. Invention is credited to Randy Jon Clark, Gary Lee Koepke, Keith Lynn Lewallen, Brent David Olson, William Robert Transue.
Application Number | 20070125043 11/656627 |
Document ID | / |
Family ID | 32312037 |
Filed Date | 2007-06-07 |
United States Patent
Application |
20070125043 |
Kind Code |
A1 |
Clark; Randy Jon ; et
al. |
June 7, 2007 |
Multi-layered fire door and method for making the same
Abstract
A door has a core that includes a porous layer having a
thickness and two opposing major surfaces. In one construction, the
core also includes three fire-retardant layers, and two of the
fire-retardant layers are separated by the porous layer. The porous
layer and the fire-retardant layers are coupled together. Other
constructions include one or more fire-retardant layers in balanced
or unbalanced placement around the porous layer.
Inventors: |
Clark; Randy Jon; (Klamath
Falls, OR) ; Koepke; Gary Lee; (Klamath Falls,
OR) ; Lewallen; Keith Lynn; (Salado, TX) ;
Olson; Brent David; (Klamath Falls, OR) ; Transue;
William Robert; (Klamath Falls, OR) |
Correspondence
Address: |
NELSON MULLINS RILEY & SCARBOROUGH, LLP
1320 MAIN STREET, 17TH FLOOR
COLUMBIA
SC
29201
US
|
Assignee: |
JELD-WEN, inc.
|
Family ID: |
32312037 |
Appl. No.: |
11/656627 |
Filed: |
January 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10284392 |
Oct 31, 2002 |
7185468 |
|
|
11656627 |
Jan 23, 2007 |
|
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Current U.S.
Class: |
52/782.1 |
Current CPC
Class: |
B32B 5/18 20130101; B32B
2266/0228 20130101; B32B 2607/00 20130101; E06B 2003/7023 20130101;
B32B 7/02 20130101; E06B 2003/7025 20130101; B32B 27/12 20130101;
B32B 21/02 20130101; B32B 2325/00 20130101; B32B 21/08 20130101;
B32B 27/302 20130101; E06B 5/16 20130101; E06B 3/7001 20130101;
B32B 2305/026 20130101; B32B 5/22 20130101; E04B 1/942 20130101;
B32B 3/30 20130101; B32B 2307/3065 20130101; B32B 7/12
20130101 |
Class at
Publication: |
052/782.1 |
International
Class: |
E04C 2/00 20060101
E04C002/00 |
Claims
1-18. (canceled)
19. A method of making a door comprising: providing a core
comprising a porous layer having two opposing major surfaces and at
least three fire-retardant layers each comprising a fiberboard; and
coupling together the porous layer and the at least three
fire-retardant layers in an unbalanced construction, wherein a
number of the at least three fire-retardant layers disposed on one
of the two opposing major surfaces of the porous layer is greater
than a number of the at least three fire-retardant layers disposed
on another one of the two opposing major surfaces of the porous
layer.
20-21. (canceled)
22. The method of making the door according to claim 19, further
comprising: coupling a first exterior layer to one surface of the
core; and coupling a second exterior layer to another surface of
the core, wherein a door blank is formed.
23. The method of making the door according to claim 22, further
comprising applying a uniform pressure to the door blank for a
period of time.
24. The method of making the door according to claim 23, wherein
the uniform pressure is in a range between about 80 and about 110
pounds per square inch and the period of time is about 30
minutes.
25-40. (canceled)
41. The method of making the door according to claim 22, further
comprising machining a grooved first pattern having a first depth
on the first exterior layer.
42. The method of making the door according to claim 41, wherein
the first depth penetrates a thickness of the first exterior layer
and a portion of a thickness of one of the at least three fire
retardant layers.
43. The method of making the door according to claim 42, further
comprising machining a grooved second pattern having a second depth
on the second exterior layer, wherein the second depth penetrates a
thickness of the second exterior layer and a portion of a thickness
of another one of the at least three fire retardant layers.
44. The method of making the door according to claim 43, wherein
the first and second depths are about the same.
45. The method of making the door according to claim 19, wherein a
density of the porous layer is at least one pound per cubic
foot.
46. The method of making the door according to claim 19, wherein
the porous layer comprises a thermoplastic polymer.
47. The method of making the door according to claim 19, wherein
the porous layer comprises a fire-retardant material.
48. The method of making the door according to claim 19, wherein a
thickness of each of the at least three fire-retardant layers is
about the same.
49. The method of making the door according to claim 48, wherein a
thickness of the porous layer is about the same as the thickness of
each of the at least three fire-retardant layers.
50. The method of making the door according to claim 19, wherein
the fiberboard comprises a medium-density fiberboard comprising a
density of at least 42 pounds per cubic foot.
Description
NOTICE OF COPYRIGHT PROTECTION
[0001] A portion of the disclosure of this patent document and its
figures contain material subject to copyright protection. The
copyright owner has no objection to the facsimile reproduction by
anyone of the patent document, but otherwise reserves all
copyrights whatsoever.
FIELD OF THE INVENTION
[0002] This invention relates to doors in general, and more
particularly to a fire door having several fire-retardant
layers.
BACKGROUND
[0003] Fire doors are designed and installed in an attempt to
protect lives and property from fire, smoke, and heat by providing
a barrier to withstand the fire, smoke, and heat for a period of
time. To be labeled or certified as a fire door, a door must
fulfill the requirements of certain codes or standards that
regulate the construction and installation of such doors. These
codes or standards include, among others, the Uniform Building Code
(UBC), and codes promulgated by the National Fire Protection
Association (NFPA), and American Society for Testing and Materials
(ASTM).
[0004] Private testing laboratories, such as Underwriters'
Laboratories and Warnock Hersey, may test for adherence to such
codes or standards, and may test for additional attributes. The
laboratories may also certify that a fire door meets fire
protection requirements after conducting testing (such as
destructive testing) of the door. Usually, this certification is
expressed as a fire-rating offering a specific level of protection
from fire, smoke, and/or heat for a limited amount of time. For
example, a 20-minute fire-rated door should, if installed
correctly, maintain its structural integrity and provide a barrier
to fire, heat, and/or smoke for at least 20 minutes. So long as a
door meets relevant fire protection requirements, its design may
vary to fulfill other design considerations, such as weight, cost
of manufacture, and aesthetic appearance.
[0005] An interior routed medium-density fiberboard (MDF) fire door
meeting current fire protection requirements generally is
constructed of a one-and-one-half inch thick sheet of MDF having a
minimum density of approximately 42 pounds per cubic foot (pcf) and
a one-eighth of an inch hardboard skin on both sides of the MDF. A
single-swing wood fire door using MDF having this thickness and
density, and that is three feet wide by eight feet high, weighs
nearly 153 pounds. Not only is such a door extremely heavy, but
manufacturing it can be costly and difficult as well.
[0006] For example, manufacturing a molded-panel fire door that
meets current fire protection requirements generally requires using
a mold. There are several ways known to prepare molds. One common
method is to use matching castings or dies. A molded door generally
has two exterior skins, and one mold is required for each skin. To
make a custom-ordered door, a new mold must be created. While using
molds to make a paneled door is generally less costly on a
high-volume basis than machining reliefs into a door, molding
custom-ordered doors can significantly add to the manufacturing
expense--in some cases, this expense can become
cost-prohibitive.
[0007] Manufacturing paneled wood doors without molds is known in
the art. Such doors generally include two exterior skins with a
core inserted between the skins. In one such conventional door, the
core generally includes a three-eights-of-an-inch-thick layer of
MDF, a three-eights-of-an-inch-thick layer of expanded polystyrene,
and another three-eights-of-an-inch-thick layer of MDF. The layers
of the core are adhered to one another, as are the external skins
and the core. Wood side stiles and top and bottom rails are then
adhered to an outer perimeter of the door. Panels are formed by
routing a series of grooves into the external skins.
SUMMARY OF THE INVENTION
[0008] The present invention includes multi-layered fire doors and
methods for making such doors. One embodiment of the present
invention provides a fire door that includes a core. The core has a
porous layer having a thickness and two opposing major surfaces.
The core also has at least three, preferably fire-retardant,
additional layers. Each of the three fire-retardant layers has a
thickness and two opposing major surfaces. The porous layer and the
at least three fire-retardant layers are coupled together. At least
two of the at least three fire-retardant layers are separated by
the porous layer from the other fire-retardant layers. The fire
door can also include first and second exterior layers, each having
a thickness and two opposed major surfaces. A grooved first pattern
can be disposed on the first exterior layer and a grooved second
pattern can be disposed on the second exterior layer.
[0009] The fire-retardant layers may be made of any suitable
material. In one embodiment, the fire-retardant layers are made of
MDF having a density of at least 42 pcf. Likewise, the porous layer
can be made of any suitable material. One example is a
thermoplastic polymer having a density of at least 1 pcf. The
thickness of each of the fire-retardant layers is the same. The
thickness of the porous layer is approximately the same as the
thickness of each fire-retardant layer. The first and second
exterior layers can include a hardboard having a density of
approximately 52 pcf. The thicknesses of the first and second
exterior layers are approximately the same.
[0010] Another embodiment of the present invention provides a fire
door that includes a core with a porous layer having a thickness of
approximately three-eighths of an inch and two opposing major
surfaces. The core also has at least two, preferably
fire-retardant, additional layers. Each of the two fire-retardant
layers has a thickness of approximately nine-sixteenths of an inch
and two opposing major surfaces. The porous layer and the at least
two fire retardant layers are coupled together. The at least two
fire-retardant layers are separated by the porous layer.
[0011] An embodiment of the present invention further provides for
methods of making a door having a core with a porous layer and two
opposing major surfaces and fire-retardant layers, each having a
thickness and two opposing major surfaces. One embodiment of a
method according to the present invention includes coupling
together a porous layer and at least three fire-retardant layers.
At least two of the fire-retardant layers are separated by the
porous layer. The door can also include first and second exterior
layers each having a thickness and two opposed major surfaces. In
one embodiment, the method according to the present invention also
includes forming a blank by coupling the first and second exterior
layers to the core. An embodiment further includes applying a
generally uniform pressure to the blank for a period of time. A
further embodiment includes machining a grooved first pattern on
the first exterior surface and machining a grooved second pattern
on the second exterior surface.
[0012] An advantage of one embodiment of the present invention is
to provide a fire-rated door that can endure a 20-minute fire test
according to at least the following standards: UBC 7-2 (1997), Part
I NFPA 252 (1999), UL 10C (1998), ASTM E 2072 (1999), and CAN4 S113
and WH-PN-014 (1985).
[0013] Another advantage of one embodiment of the present invention
is to provide a lighter-weight fire-rated door, i.e., approximately
120 pounds (having dimensions of three feet by eight feet by
one-and-three-quarters of an inch), than is currently
available.
[0014] Yet another advantage of one embodiment of the present
invention is to reduce the complexity and cost of manufacturing
wood, paneled fire-rated doors by forming panels in the door by
machining, instead of molding.
[0015] A further advantage of one embodiment of the present
invention is to increase a fire door manufacturer's flexibility in
manufacturing customer-ordered wood, paneled fire-rated doors by
forming panels in the door by machining, rather than by
molding.
[0016] Yet a further advantage of one embodiment of the present
invention is to improve the insulative qualities, or R-value, of
fire-rated doors.
[0017] An additional advantage of one embodiment of the present
invention is to improve the sound dampening of fire-rated
doors.
[0018] Yet another additional advantage of one embodiment of the
present invention is to reduce a fire-rated door's susceptibility
to warping caused by moisture.
[0019] Additional advantages of embodiments of the invention are
set forth in the detailed description that follows and will become
more apparent to those skilled in the art upon examination of the
following.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings, which are incorporated herein and
constitute part of this specification, help to illustrate
embodiments of the invention. In the drawings, like numerals are
used to indicate like elements throughout.
[0021] FIG. 1 is a front plan view of a double door system
according to an embodiment of the invention.
[0022] FIG. 2 is a partially-exploded orthogonal view of the door
of FIG. 1 prior to machining panels.
[0023] FIG. 3 is a flow diagram of a method of making the door of
FIG. 1.
[0024] FIG. 4 is a flow diagram of a method of making a door blank
of FIG. 1.
[0025] FIG. 5 is a front plan view of a door according to another
embodiment of the invention.
[0026] FIG. 6 is a partially-exploded orthogonal view of the door
of FIG. 5.
DETAILED DESCRIPTION
[0027] The present invention includes doors, parts of doors, and
methods of making doors. One embodiment of the present invention
includes a multilayer fire door and methods of making such a
door.
[0028] FIG. 1 shows a front plan view of a door according to an
embodiment of the invention. A standard-pair wood, paneled fire
door 100 includes two separate but adjacent doors, 110 and 210. The
door 100 can also be a single-swing door (not shown). As doors 110
and 210 are identical in material respect, only door 110 will be
described in detail.
[0029] Door 110 has a major axis and a minor axis. The major axis
extends vertically and the minor axis extends horizontally. The
door 110 includes an outer peripheral frame including a bottom rail
112, a top rail 114, and a pair of side stiles 116 and 118. The top
rail 114 and the bottom rail 112 extend horizontally along the
minor axis and generally parallel to one another. The side stiles
116 and 118 extend vertically along the major axis and generally
parallel to one another. The top rail 114 and the bottom rail 112
are generally perpendicular to the side stiles 116 and 118. The top
rail 114 and the bottom rail 112 are made of MDF having a density
of at least 42 pcf. The side stiles 116 and 118 are made of pine or
fir, preferably, having a minimum specific gravity of 0.34. The
side stiles 116 and 118 can be made of another type or kind of
wood. Preferably, the specific gravity of that wood is a minimum of
0.34. Moreover, the rails 112 and 114, and the stiles 116 and 118
may be made of any suitable material.
[0030] The door 110 also includes hinges 120 to mount the door 110
to a hinge jamb 410 to allow the door 110 to swing open and closed.
As shown in FIG. 1, there are four hinges 120 mounting the door 110
to the hinge jamb 124. The number of hinges 120 can vary to
accommodate various design considerations, such as the weight of
the door 110. A handle 122 is provided on the door 110 to operate a
latch (not shown), which maintains the door 110 in a closed
position. While door 210 can be opened and closed, the door 210
preferably is maintained in a closed position. The latch on door
110 maintains the door 110 in a closed position by engaging with a
complementary recess (not shown) on door 210. A width and a height
of the doors 110 and 210 can vary but, in general, should not
exceed approximately three feet in width and eight feet in
height.
[0031] In general, the above description of the door's features
visible in FIG. 1 comprise conventional door construction. It is
included here for completeness, and to aid one of ordinary skill in
the art in constructing a door according to the present
invention.
[0032] Referring now to FIG. 2, the door 110 includes a core 130,
which is disposed between a front face 140 and a rear face 190. The
core 130 shown has several layers of material. The layers 150, 160,
170, 180 may be made of any suitable material. Preferably, at least
three of the layers 150, 160, 180 are made of fire-retardant
material. Preferably, the layers of fire-retardant material
comprises MDF. Most preferably, the layers comprise MDF having a
density of approximately 42 pcf. The core 130 includes a first
fiberboard 150, a second fiberboard 160, and a third fiberboard
180. Disposed between the second and third fiberboards 160 and 180
is a layer of porous material 170. The porous layer 170 may be made
of any suitable material. Preferably, the porous layer 170 is a
foam sheet comprised of a thermoplastic polymer, such as expanded
polystyrene, having a density of at least 1 pcf. Alternatively, the
porous layer 170 can be a fire-retardant material.
[0033] Each of the front face 140, the rear face 190, the first
fiberboard 150, the second fiberboard 160, the third fiberboard
180, and the porous layer 170 has two major surfaces and a
thickness. A height and width of each of the front face 140, the
rear face 190, the first fiberboard 150, the second fiberboard 160,
the third fiberboard 180, and the porous layer 170 correspond
generally to the height and width of the door 110.
[0034] An exemplary embodiment of such a door 110 comprises each of
the front face 140, the rear face 190, the first fiberboard 150,
the second fiberboard 160, the porous layer 170, and the third
fiberboard 180 having dimensions of three feet wide by eight feet
high. This exemplary embodiment also comprises the thickness of
both the front face 140 and the rear face 190 being
one-eighth-of-an-inch. In this exemplary embodiment the thickness
of each of the first fiberboard 150, the second fiberboard 160, the
porous layer 170, and the third fiberboard 180 is
three-eighths-of-an-inch. Alternatively, any other suitable
dimensions can be provided.
[0035] The front face 140 and the rear face 190 may be made of any
suitable material. Preferably, the front face 140 and the rear face
190 are a hardboard made of wood fibers having a density of at
least 52 pcf. The hardboard of the front face 140 and the rear face
190 can be made of any other suitable material, preferably, having
a density of at least 52 pcf. The thicknesses of the front face 140
and the rear face 190 shown can be the same. The thickness of the
front face 140 shown is one-eighth of an inch, as is the thickness
of the rear face 190. Alternatively, these thicknesses can be
approximately one-eighth of an inch or any other suitable
thickness. The two major surfaces of the front face 140 include a
front-facing surface 141 and a rear-facing surface (not shown). The
front-facing surface 141 and the rear-facing surface of the front
face 140 are disposed on opposing sides of the front face 140.
Either the front-facing surface 141 or the rear-facing surface of
the front face 140 can be disposed adjacent to one of the major
surfaces of the first fiberboard 150. In the embodiment shown in
FIG. 2, the rear-facing surface of the front face 140 is disposed
adjacent to the first fiberboard 150.
[0036] The first fiberboard 150 can be formed by disposing a
vertical splice 152 adjacent to a main sheet 154. Alternatively,
the first fiberboard 150 can be a single sheet. The vertical splice
152 can be disposed proximate the side stile 116. The width of the
vertical splice 152 can be any suitable dimension. For example, the
width of the vertical splice 152 can be six inches. The width of
both the vertical splice 152 and the main sheet 154 correspond
generally to the width of the door 110. Thus, the maximum
dimensions of the fiberboard 150 are three feet wide by eight feet
high. The height of the vertical splice 152 is preferably the same
as the height of the main sheet 154. Preferably, the dimensions of
the side stiles 116 and 118 are one-and-one-quarter inches by
one-and-one-half inches. Preferably, the dimensions of the bottom
rail 112 and the top rail 114 is one-and-one-quarter inches by
one-and-one-half inches by thirty-three-and-seven-eighths inches.
Alternatively, any other suitable dimensions can be used.
[0037] The thickness of the first fiberboard 150 shown is
three-eighths of an inch. Alternatively, the thickness can be
approximately three-eights of an inch or any other suitable
thickness. The two major surfaces of the first fiberboard 150
include a front-facing surface 151 and a rear-facing surface (not
shown). The front-facing surface 151 and the rear-facing surface of
the first fiberboard 150 are disposed on opposing sides of the
first fiberboard 150. Either the front-facing surface 151 or the
rear-facing surface of the first fiberboard 150 can be disposed
adjacent to the rear-facing surface of the front face 140.
According to the embodiment, the front-facing surface 151 of the
first fiberboard 150 is disposed adjacent to the rear-facing
surface of the front face 140. Thus, the rear-facing surface of the
first fiberboard 150 is disposed adjacent to one of the major
surfaces of the second fiberboard 160.
[0038] The second fiberboard 160 is formed by disposing a vertical
162 splice adjacent to a main sheet 164. Alternatively, the second
fiberboard 160 can be a single sheet. The vertical splice 162 is
disposed proximate the side stile 118. The width of the vertical
splice 162 can be any suitable dimension. For example, the width of
the vertical splice can be six inches. The width of both the
vertical splice 162 and the main sheet 164 corresponds to the width
of the door 110. Thus, the maximum dimensions of the fiberboard 160
are three feet wide by eight feet high. The height of the vertical
splice 162 is the same as the height of the main sheet 164.
[0039] The thickness of the second fiberboard 160 is preferably
three-eighths of an inch. It can be approximately three-eighths of
an inch or another, selected thickness. The two major surfaces of
the second fiberboard 160 include a front-facing surface 161 and a
rear-facing surface (not shown). The front-facing surface 161 and
the rear-facing surface of the second fiberboard 160 can be
disposed on opposing sides of the second fiberboard 160. Either the
front-facing surface 161 or the rear-facing surface of the second
fiberboard 160 can be disposed adjacent to the rear-facing surface
of the first fiberboard 150. According to the embodiment, the
front-facing surface 161 of the second fiberboard 160 is disposed
adjacent to the rear-facing surface of the first fiberboard 150.
Thus, the rear-facing surface of the second fiberboard 160 is
disposed adjacent to one of the major surfaces of the porous layer
170.
[0040] Preferably, the porous layer 170 is formed by disposing a
horizontal splice 172 adjacent to a main sheet 174. Alternatively,
the porous layer 170 can be a single sheet. The horizontal splice
172 is disposed proximate the top rail 114. Alternatively, the
horizontal splice 172 is disposed proximate the bottom rail 112.
The dimension of the horizontal splice 172 can be any suitable
dimension. For example, the height of the splice 172 can be 16
inches. The height of both the horizontal splice 172 and the main
sheet 174 correspond to the height of the door 110. Thus, the
maximum dimensions of the porous layer 170 are three feet wide by
eight feet high. The width of the horizontal splice 172 is the same
as the width of the main sheet 174. The thickness of the porous
layer 170 shown is three-eighths of an inch. In another embodiment,
it is approximately three-eighths of an inch or another
thickness.
[0041] The two major surfaces of the porous layer 170 include a
front-facing surface 171 and a rear-facing surface (not shown). The
front-facing surface 171 and the rear-facing surface of the porous
layer 170 are disposed on opposing sides of the porous layer 170.
Either the front-facing surface 171 or the rear-facing surface of
the porous layer 170 can be disposed adjacent to the rear-facing
surface of the second fiberboard 160. According to the embodiment,
the front-facing surface 171 of the porous layer 170 is disposed
adjacent to the second fiberboard 160. Thus, the rear-facing
surface of the porous layer 170 is disposed adjacent to one of the
major surfaces of the third fiberboard 180.
[0042] The third fiberboard 180 is formed by disposing a vertical
splice 182 adjacent to a main sheet 184. Alternatively, the third
fiberboard 180 can be a single sheet. The vertical splice 182 is
disposed proximate the side stile 116. Alternatively, the vertical
splice 182 can be disposed proximate the side stile 114. The width
of the vertical splice 182 can be any suitable dimension. For
example, the width of the vertical splice 182 can be approximately
six inches. Preferably, the width of both the vertical splice 182
and the main sheet 184 corresponds to the width of the door 110.
Thus, the maximum dimensions of the third fiberboard 180 are three
feet wide by eight feet high. The height of the vertical splice 182
is the same as the height of the main sheet 184.
[0043] The thickness of the third fiberboard 180 is preferably
three-eighths of an inch. Alternatively, the thickness can be
approximately three-eights of an inch or another suitable
thickness. The two major surfaces of the third fiberboard 180
include a front-facing surface 181 and a rear-facing surface (not
shown). The front-facing surface 181 and the rear-facing surface of
the third fiberboard 180 are disposed on opposing sides of the
third fiberboard 180. Either the front-facing surface 181 or the
rear facing surface of the third fiberboard 180 can be disposed
adjacent to the rear-facing surface of the porous layer 170.
According to the embodiment described herein, the front-facing
surface 181 of the third fiberboard 180 is disposed adjacent to the
rear-facing surface of the porous layer 170. Thus, the rear-facing
surface of the third fiberboard is disposed adjacent to one of the
major surfaces of the rear face 190.
[0044] As described above, the rear face 190 includes a hardboard
preferably having a density of at least 52 pcf and the thickness is
one-eighth of an inch. Alternatively, the thickness can be
approximately one-eighth of an inch or another suitable thickness.
The two major surfaces of the rear face 190 include a front-facing
surface 191 and a rear-facing surface (not shown). The front-facing
surface 191 and the rear-facing surface of the rear face 190 are
disposed on opposing sides of the rear face 190. Either the
front-facing surface 191 or the rear-facing surface of the rear
face 190 can be disposed adjacent to the rear-facing surface of the
third fiberboard 180. According to the embodiment, the front-facing
surface 191 of the rear face 190 is disposed adjacent to the
rear-facing surface of the third fiberboard 180.
[0045] To enhance the aesthetic appearance of the door 110, a
series of grooves 142 are disposed in the front face 140 of the
door 110 forming panels 144. Alternatively, the door 110 can be
flush and have no panels. As shown in FIG. 1, one embodiment
preferably includes twelve panels 144 formed in the front face 140
of the door 110. The number and shape of the panels 144 can vary
depending on the design desired. As will be described in more
detail below, the grooves 142 are formed by machining, such as
routing, into the door 110. In the embodiment, the depth of the
grooves 142 preferably are seven-sixteenths of an inch. Thus, the
grooves 142 penetrate the entire thicknesses of the front face 140
and nearly the entire thickness of the first fiberboard 150.
Although not shown, panels are preferably formed in the rear face
190. In general, the depth of the grooves in the panels formed in
the rear face 190 preferably are the same as that of the front face
140, but alternatively, can be different than that of the front
face. Thus, the grooves in the rear face 190 penetrate the entire
thickness of the rear face 190 and nearly the entire thickness of
the third fiberboard 180.
[0046] As described above, a conventional door made entirely of MDF
weighs approximately 153 pounds. The weight of the door 110
according to the embodiment as described above is substantially
less. Using a similarly dimensioned door, i.e., three feet wide and
eight feet high, with the thicknesses described above, the door 110
according to the embodiment should weigh approximately 120 pounds.
The weight of the door 110 is reduced further by the weight of the
material removed by machining the grooves to form the panels in the
door 110.
[0047] A method of making the door 110 according to an embodiment
will be described next with reference to FIG. 3. As described
above, the core 130 includes the first fiberboard 150, the second
fiberboard 160, the third fiberboard 180, and the porous layer 170.
The method includes coupling together the porous layer 170 and the
first fiberboard 150, the second fiberboard 160, and the third
fiberboard 180. Preferably, coupling refers to joining by adhering
surfaces together with an adhesive, such as glue or cement, as
described below. A variety of commercially-available adhesives can
be used, including, for example, Tightbond.RTM. 100 manufactured by
Franklin International, RK-3490 manufactured by H.B. Fuller Co.,
and WD-1300C0-2F manufactured by Specialty Polymers, Inc. Other
suitable methods of joining surfaces together can be used.
[0048] In the embodiment shown in FIG. 2, two of the first
fiberboard 150, the second fiberboard 160, and the third fiberboard
180 are separated by the porous layer 170. An embodiment of the
method of making the core 130 of the door 110 is described in
further detail below and in FIG. 4.
[0049] FIG. 3 is a flow chart diagram illustrating a method of
making the door 110. A door blank (not shown) is first assembled as
indicated by block 310. The rear face 190 can be placed on a flat
surface, such as a lay-up table (not shown). Either the
front-facing surface 191 or the rear-facing surface of the rear
face 190 can be placed on the flat surface. According to the
embodiment, the rear-facing surface of the rear face 190 is placed
on the flat surface.
[0050] Preferably, an adhesive (not shown) is applied to at least
one surface of each of the side stiles 116 and 118 and the bottom
rail 112 and the top rail 114. As indicated by block 311 in FIG. 4,
the side stiles 116 and 118 and the bottom rail 112 and the top
rail 114 are attached, in positions corresponding to those shown in
FIG. 2, on the door blank as thus far constructed.
[0051] Preferably, the adhesive is applied to both the front-facing
surface 181 and the rear-facing surface of the third fiberboard
180. Alternatively, the adhesive can be applied to either the
front-facing surface 181 or the rear-facing surface of the third
fiberboard 180. As indicated by block 312 in FIG. 4, either the
front-facing surface 181 or the rear-facing surface of the third
fiberboard 180 can be placed on the rear face 190. Preferably, the
rear-facing surface of the third fiberboard 180 is placed on and
adhered to the front-facing surface 191 of the rear face 190.
[0052] Preferably, the adhesive is applied to both the front-facing
surface 171 and the rear-facing surface of the porous layer 170.
Alternatively, the porous layer 170 can be placed on the third
fiberboard 180 with no adhesive applied to the porous layer 170.
Alternatively, the adhesive can be applied to either the
front-facing surface 171 or the rear-facing surface of the porous
layer 170. As indicated by block 313 in FIG. 4, either the
front-facing surface 171 or the rear-facing surface of the porous
layer 170 can be placed on the third fiberboard 180. Preferably,
the rear-facing surface of the porous layer 170 is placed on the
front-facing surface 181 of the third fiberboard 180.
[0053] Preferably, the adhesive is applied to both the front-facing
surface 161 and the rear-facing surface of the second fiberboard
160. Alternatively, the adhesive can be applied to either the
front-facing surface 161 or the rear-facing surface of the second
fiberboard 160. As indicated by block 314 in FIG. 4, either the
front-facing surface 161 or the rear-facing surface of the second
fiberboard 160 can be placed on the porous layer 170. Preferably,
the rear-facing surface of the second fiberboard 160 preferably is
placed on the front-facing surface 171 of the porous layer 170.
[0054] Preferably, the adhesive is applied to both the front-facing
surface 151 and the rear-facing surface of the first fiberboard
150. Alternatively, the adhesive can be applied to either the
front-facing surface 151 or the rear-facing surface of the first
fiberboard 150. As indicated by block 315 in FIG. 4, either the
front-facing surface 151 or the rear-facing surface of the first
fiberboard 150 can be placed on the second fiberboard 160.
Preferably, the rear-facing surface of the first fiberboard 150 is
placed on and adhered to the front-facing surface 161 of the second
fiberboard 161.
[0055] As indicated by block 316 in FIG. 4, either the front-facing
surface 141 or the rear-facing surface of the front face 140 can be
placed on the first fiberboard 150. Preferably, the rear-facing
surface of the front face 140 is placed on the front-facing surface
151 of the first fiberboard 150. The door blank of the embodiment
has thus been constructed.
[0056] As indicated by block 320 in FIG. 3, pressure is applied to
the door blank. Preferably, several door blanks are placed one atop
the other and placed in a press (not shown) at the same time.
Alternatively, only one door is placed in the press. A pressure in
a range between 80 and 110 pounds per square inch (psi) is applied
to the door blank for 30 minutes. Alternatively, the pressure can
be in a range between approximately 80 psi and approximately 110
psi. Alternatively, the time the pressure is applied can be
approximately 30 minutes. Alternatively, any other suitable
pressure and time can be used. In general, press time will be
longer when the ambient temperature is below 65 degrees F. The
pressure is removed from the door blank and the adhesive is allowed
to adhere for at least approximately eight hours. During this time,
the door blank is not manipulated. As indicated by block 330 in
FIG. 3, the door blank is cut to a desired width and height.
Preferably, the maximum width does not exceed three feet and the
maximum height does not exceed eight feet.
[0057] As indicated by block 340, a series of grooves 142 are
machined into the front face 140 to form the panels 144.
Alternatively, the front face 140 can be flush with no panels. Once
the panels 144 have been formed, the blank is turned over so that
another series of grooves are machined into the rear face 190 to
form other panels. The machining is preferably accomplished by
routing. Generally, a computer program is written to control a
computer numerical control (CNC) milling machine (not shown). The
door blank is placed into the milling machine and one side of the
door blank is milled according to the design entered into the CNC
milling machine. Hardware, such as the door handle 122 is
installed. The door 110 can thus be installed into a door frame
132.
[0058] Other variations to the embodiments described above are
possible. For example, the thickness of any of the layers forming
the door can be varied from that described above. Similarly,
varying the density of the layers forming the door in the above
embodiments is certainly within the ordinary skill in the art.
[0059] The embodiments shown in FIG. 2 are an unbalanced core
construction; that is, in the embodiments shown in FIG. 2, the
number of fire-retardant layers on one side of the porous layer is
not equal to the number of fire-retardant layers on the other side
of the porous layer. Specifically, the embodiments shown in FIG. 2
include one fire-retardant layer on one side of the porous layer
and two fire-retardant layers on the other side of the porous
layer. The number of layers on each side of the porous layer can be
varied in other embodiments. For example, there can be two layers
on one side of the porous layer and three layers on the other side.
As another example, there can be an equal number of layers on each
side of the porous layer but the thickness of the fire-retardant
layers on one side of the porous layer is different than the
thickness of the fire-retardant layers on the other side.
[0060] Furthermore, a core of the door in accordance with the
present invention can have a balanced construction. In order words,
a balanced core construction has an equal number of layers on each
side of the porous layer. For example, there can be one
fire-retardant layer on each side of the porous layer. There can be
more than one fire-retardant layer on each side of the porous
layer. Moreover, in the balanced construction, the total thickness
of fire-retardant layers on one side of the porous layer can be the
same as the total thickness of fire-retardant layers on the other
side of the porous layer even if the number of layers on each side
differs. An example of an embodiment disclosing a balanced
construction will be described below.
[0061] FIG. 5 shows a front plan view of a door according to
another embodiment of the invention. A standard-pair wood, paneled
fire door 400 includes two separate but adjacent doors, 410 and
510. The door 400 can also be a single-swing door (not shown). As
the external appearance of door 400 and door 100 are identical in
material respect--including the grooves and panels, these identical
details will not be repeated. Thus, only the core 430 will be
described in detail below. Furthermore, as doors 410 and 510 are
identical in material respect, only door 410 will be described in
detail.
[0062] Referring now to FIG. 6, the door 410 includes a core 430,
which is disposed between a front face 440 and a rear face 490. The
core 430 shown has several layers of material. The layers 450, 470,
and 480 may be made of any suitable material. Preferably, at least
two of the layers 450 and 480 are made of fire-retardant material.
Preferably, the layers of fire-retardant material comprise an MDF.
Most preferably, the layers comprise MDF having a density of
approximately 42 pcf. The core 430 includes a first fiberboard 450
and a second fiberboard 480. Disposed between the first and second
fiberboards 450 and 480 is a layer of porous material 470. The
porous layer 470 may be made of any suitable material. Preferably,
the porous layer 470 is a foam pad comprised of a thermoplastic
polymer, such as expanded polystyrene, having a density of at least
1 pcf.
[0063] Each of the first fiberboard 450, the second fiberboard 480,
and the porous layer 470 has two major surfaces and a thickness. A
height and width of each of the first fiberboard 450, the second
fiberboard 480, and the porous layer 470 correspond generally to
the height and width of the door 410.
[0064] An exemplary embodiment of a core 430 of such a door 410
comprises each of the first fiberboard 450, the second fiberboard
480, and the porous layer 470 having dimensions of three feet wide
by eight feet high. In this exemplary embodiment the thickness of
each of the first fiberboard 450 and the second fiberboard 480 is
nine-sixteenths-of-an-inch and the thickness of the porous layer
470 is three-eighths-of-an-inch. Alternatively, any other suitable
dimensions can be provided.
[0065] In the embodiment shown in FIG. 6, the first fiberboard 450
can be formed by disposing a vertical splice 452 adjacent to a main
sheet 454. Alternatively, the first fiberboard 450 can be a single
sheet. The vertical splice 452 is preferably disposed proximate the
side stile 416. The width of the vertical splice 452 can be any
suitable dimension. For example, the width of the vertical splice
can be six inches. The width of both the vertical splice 452 and
the main sheet 454 correspond generally to the width of the door
410. Thus, the maximum dimensions of the first fiberboard 450 are
three feet wide by eight feet high. The height of the vertical
splice 452 is the same as the height of the main sheet 454.
Preferably, the dimensions of side stiles 416 and 418 are
one-and-one-quarter inches by one-and-one-half inches. Preferably,
the dimensions of the bottom rail 412 and the top rail 414 are
one-and-one-quarter inches by one-and-one-half inches by
thirty-three-and-seven-eighths inches.
[0066] The thickness of the first fiberboard 450 shown is
nine-sixteenths of an inch. Alternatively, the thickness can be any
other suitable thickness. The two major surfaces of the first
fiberboard 450 include a front-facing surface 451 and a rear-facing
surface (not shown). The front-facing surface 451 and the
rear-facing surface of the first fiberboard 450 are disposed on
opposing sides of the first fiberboard 450. Either the front-facing
surface 451 or the rear-facing surface of the first fiberboard 450
can be disposed adjacent to a rear-facing surface of a front face
440. According to the embodiment, the front-facing surface 451 of
the first fiberboard 450 is disposed adjacent to the rear-facing,
surface of the front face 440. Thus, the rear-facing surface of the
first fiberboard 450 is disposed adjacent to one of the major
surfaces of the porous layer 470.
[0067] Preferably, the porous layer 470 is formed by disposing a
horizontal splice 472 adjacent to a main sheet 474. Alternatively,
the porous layer 470 can be a single sheet. The horizontal splice
472 is disposed proximate the top rail 414. Alternatively, the
horizontal splice 472 is disposed proximate the bottom rail 412.
The height of the horizontal splice 472 can be any suitable
dimension. For example, the height of the horizontal splice 472 can
be 16 inches. The height of both the horizontal splice 472 and the
main sheet 474 corresponds to the height of the door 410. Thus, the
maximum dimensions of the porous layer 470 are three feet wide by
eight feet high. The width of the horizontal splice 472 is the same
as the width of the main sheet 474. The thickness of the porous
layer 470 is three-eighths of an inch. Alternatively, the thickness
can be any other suitable thickness.
[0068] The two major surfaces of the porous layer 470 include a
front-facing surface 471 and a rear-facing surface (not shown). The
front-facing surface 471 and the rear-facing surface of the porous
layer 470 are disposed on opposing sides of the porous layer 470.
Either the front-facing surface 471 or the rear-facing surface of
the porous layer 470 can be disposed adjacent to the rear-facing
surface of the first fiberboard 450. According to this embodiment,
the front-facing surface 471 of the porous layer 470 is disposed
adjacent to the first fiberboard 450. Thus, the rear-facing surface
of the porous layer 470 is disposed adjacent to one of the major
surfaces of the second fiberboard 480.
[0069] The second fiberboard 480 is formed by disposing a vertical
splice 482 adjacent to a main sheet 484. Alternatively, the second
fiberboard 480 can be a single sheet. The vertical splice 482 is
disposed proximate the side stile 416. Alternatively, the vertical
splice 482 can be disposed proximate the side stile 414. The width
of the vertical splice 482 can be any suitable dimension. For
example, the width of the vertical splice 482 can be six inches.
Preferably, the width of both the vertical splice 482 and the main
sheet 484 corresponds to the width of the door 410. Thus, the
maximum dimensions of the second fiberboard 480 are three feet wide
by eight three high. The height of the vertical splice 482 is the
same as the height of the main sheet 484.
[0070] The thickness of the second fiberboard 480 is preferably
nine-sixteenths of an inch. Alternatively, the thickness can be any
other suitable thickness. The two major surfaces of the second
fiberboard 480 include a front-facing surface 481 and a rear-facing
surface (not shown). The front-facing surface 481 and the
rear-facing surface of the second fiberboard 480 are disposed on
opposing sides of the second fiberboard 480. Either the
front-facing surface 481 or the rear facing surface of the second
fiberboard 480 can be disposed adjacent to the rear-facing surface
of the porous layer 470. According to this embodiment, the
front-facing surface 481 of the second fiberboard 480 is disposed
adjacent to the rear-facing surface of the porous layer 470. Thus,
the rear-facing surface of the second fiberboard 480 is disposed
adjacent to one of the major surfaces of the rear face 490.
[0071] While the present invention has been disclosed with
reference to certain embodiments, numerous modifications,
alterations, and changes to the described embodiments are possible
without departing from the sphere and scope of the present
invention, as defined by the appended claims. Accordingly, it is
intended that the present invention not be limited to the described
embodiments, but that it has the full scope defined by the language
of the following claims, and equivalents thereof.
* * * * *