U.S. patent application number 10/155222 was filed with the patent office on 2003-12-04 for reinforced mineral core for fire doors.
Invention is credited to Fortin, Andre, Juhl, Leo F., Nielsen, Bent.
Application Number | 20030221372 10/155222 |
Document ID | / |
Family ID | 29582158 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030221372 |
Kind Code |
A1 |
Fortin, Andre ; et
al. |
December 4, 2003 |
Reinforced mineral core for fire doors
Abstract
A mineral core for a door includes a substantially planar slab
having a front face, a rear face, and top, bottom and side edges; a
plurality of grooves formed in at least one of said front and rear
faces, each groove having a reinforcing strip secured therein.
Inventors: |
Fortin, Andre; (Lennoxville,
CA) ; Juhl, Leo F.; (Nykoebing Mors, DK) ;
Nielsen, Bent; (Brovst, DK) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
8th Floor
1100 North Glebe Road
Arlington
VA
22201
US
|
Family ID: |
29582158 |
Appl. No.: |
10/155222 |
Filed: |
May 28, 2002 |
Current U.S.
Class: |
49/507 |
Current CPC
Class: |
E06B 5/16 20130101; E06B
2003/7028 20130101 |
Class at
Publication: |
49/507 |
International
Class: |
E04C 002/38 |
Claims
What is claimed is:
1. A mineral core for a door comprising a substantially planar slab
having a front face, a rear face, and top, bottom and side edges;
and a plurality of grooves formed in at least one of said front and
rear faces, each groove having a reinforcing strip secured
therein.
2. The mineral core of claim 1 wherein said grooves and reinforcing
strips extend substantially parallel to said side edges and
substantially between said top and bottom edges.
3. The mineral core of claim 1 wherein each reinforcing strip is
press fit in a respective one of said grooves.
4. The mineral core of claim 3 wherein each reinforcing strip is
also adhesively secured within a respective one of said
grooves.
5. The mineral core of claim 1 wherein said reinforcing strips are
made of wood, polylaminate, MDF boards or HDF boards.
6. The mineral core of claim 1 wherein said reinforcing strips are
made of glass fiber strips, ceramic fiber strips, glass fibers,
ceramic fibers or paper in a matrix bonded by cement, magnesia
cement, colloidal silica, colloidal alumina, potassium silicate or
sodium silicate.
7. The mineral core of claim 1 wherein said grooves are formed in
both said front and rear faces of said core, with a reinforcing
strip in each groove.
8. The mineral core of claim 7 wherein said respective pairs of
grooves on said front and rear faces lie in single planes extending
through the core, parallel to said side edges.
9. The mineral core of claim 7 wherein said grooves on said front
and rear faces are laterally offset from each other.
10. The mineral core of claim 1 wherein grooves are each about 7/8
inch wide and 1/8 inch deep.
11. The mineral core of claim 4 wherein said adhesive is a
potassium or sodium silicate glue.
12. A reinforced door construction comprising: a core including a
substantially planar slab having a front face, a rear face and top,
bottom and side edges with rails along said top and bottom edges
and stiles along said side edges; a plurality of grooves formed in
at least one of said front face and said rear face; and a
reinforcing strip pressed into each of said grooves.
13. The reinforced door construction or claim 12 wherein said
reinforcing strips are adhesively secured within said grooves.
14. The reinforced door of claim 13 wherein said reinforcing strips
are made of wood, polylaminate, MDF boards or HDF boards.
15. The reinforced door of claim 14 wherein said reinforcing strips
are made of glass fiber strips, ceramic fiber strips, glass fibers,
ceramic fibers or paper in a matrix bonded by cement, magnesia
cement, colloidal silica, colloidal alumina, potassium silicate or
sodium silicate.
16. The reinforced door of claim 12 wherein said grooves are formed
in both said front and rear faces of said core, with a reinforcing
strip in each groove.
17. The reinforced door of claim 16 wherein said respective pairs
of grooves on said front and rear faces lie in single planes
extending through the core, parallel to said side edges.
18. The reinforced door of claim 16 wherein said grooves on said
front and rear faces are laterally offset from each other.
19. The reinforced door of claim 12 wherein grooves are each about
7/8 inch wide and 1/8 inch deep.
20. The reinforced door of claim 13 wherein said adhesive is a
potassium or sodium silicate glue.
21. The reinforced door of claim 12 wherein said grooves and
reinforcing strips extend into said rails.
22. The reinforced door of claim 12 wherein said grooves extend
substantially parallel to said side edges, at least between said
top and bottom edges of said core.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] This invention relates to doors of wood or timber
construction, and particularly to fire rated doors having mineral
cores.
[0002] It is well known to incorporate inorganic minerals into the
cores of fire doors of wood construction to obtain better
resistance to fire. The typical construction of a wood door
includes a mineral core with stiles and rails applied along the
side and top and bottom edges, respectively, of the mineral core.
The core is then interlocked by gluing the core between two outer
layers of, for example, plywood, MDF-boards, HDF-boards,
polylaminates or other organic cover skins. Hardwood trim and
edging or lipping are then typically applied along the edges of the
door.
[0003] One problem with lightweight timber fire door cores has been
an inability to obtain sufficient strength in the core to resist a
hose stream test, immediately following a fire test. The inner
lightweight mineral core material in particular has demonstrated
weakness, i.e., cracking, resulting in failure of the tests.
[0004] The present invention relates to the incorporation of at
least one and preferably a plurality of reinforcing strips in the
surface of the lightweight core material to substantially increase
the resistance of the core to the fire hose stream according to
UL10C and UBC7-2-97. Preferably, the reinforcing strips are
oriented parallel to the core side edges, i.e., so that the strips
run from top to bottom of the core.
[0005] To achieve resistance to the fire hose stream, especially
after 45 or more minutes, the present invention in one exemplary
embodiment secures a plurality of reinforcing strips into grooves,
via suitable adhesive, on at least one of the front and rear
surfaces of the lightweight core material. It will be appreciated,
however, that the reinforcing strips can be applied to both sides
of the core to obtain an even more rigid and stronger core. The
strips themselves may consist of rigid or reinforced material of
organic or inorganic origin.
[0006] The door core construction may be formed by press fitting
the reinforcing strips within the preformed grooves in the surface
of one or both of the rear and front surfaces or faces of the
lightweight core material. This can be done sequentially or
simultaneously on both sides. The adhesive used to secure the
strips to the core may be cement, colloidal matter, inorganic or
organic glue. The preferred fixing agent or adhesive is an
inorganic silicate glue.
[0007] Accordingly, in its broader aspects, the present invention
relates to a mineral core for a door comprising a substantially
planar slab having a front face, a rear face, and top, bottom and
side edges; and a plurality of grooves formed in at least one of
the front and rear faces, each groove having a reinforcing strip
secured therein.
[0008] In another aspect, the invention relates to a reinforced
door construction comprising a core including a substantially
planar slab having a front face, a rear face and top, bottom and
side edges with rails along the top and bottom edges and stiles
along the side edges; a plurality of grooves formed in at least one
of the front face and the rear face; and a reinforcing strip
pressed into each of the grooves.
[0009] A detailed description of the invention, utilizing reference
numerals keyed to the various figures, is provided below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a front elevation of a core construction for a
door in accordance with one exemplary embodiment of the
invention.
[0011] FIG. 2 is a cross section of the core taken through the line
2-2 in FIG. 1;
[0012] FIG. 3 is an enlarged detail taken from FIG. 2;
[0013] FIG. 4 is a cross section of the core taken through the line
4-4 in FIG. 1;
[0014] FIG. 5 is an enlarged detail taken from FIG. 4;
[0015] FIG. 6 is an exploded front elevation of a core construction
in accordance with an alternative embodiment of the invention;
and
[0016] FIG. 7 is another exploded front elevation of a core
construction in accordance with another alternative embodiment of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] With reference to FIGS. 1-5, one exemplary embodiment of the
invention includes a reinforced core construction 10 for a fire
resistant door that is made up of a lightweight mineral core 12
having a front surface or face 14 and a rear surface or face 16.
Along the sides of the core, stiles 18 are fixed to the core edges
and typically include a dense mineral stile 20 and a timber trim
strip 22 (FIG. 5). Upper and lower rails 24 include similar dense
mineral rails 26, and timber trim strips 28, similar to the stiles
18. The stiles 18 and rails 24 are preferably glued to the inner,
lightweight core. The core 12 may be made of lightweight gypsum,
low density calcium silicate slabs, vermiculite slabs, perlite
slabs, lightweight castable, micro porous slabs or glass bobble
slabs. The core 12 is formed with a plurality of longitudinally
extending grooves 30 (FIG. 3) that are parallel to the stiles 18,
and in laterally spaced relationship along the width of the core.
The grooves 30 extend from top to bottom of the core, on at least
one of the front and rear faces 14 or 16 of the core. Press fit
within the grooves are reinforcing strips 32. Each strip 32 is
preferably about 7/8 inch wide (20 mm) and 1/8 inch (3 mm) thick
and is press fit and glued into a respective groove 30 that is
formed of slightly lesser width and thickness dimensions.
[0018] The strips 32 are made, preferably, of rigid or reinforced
material of either organic or inorganic origin. Suitable materials
include wood, polylaminate, MDF boards, HDF boards or other organic
reinforced strips. Inorganic strips may include glass fiber strips,
ceramic fiber strips, ceramic paper, glass fibers, ceramic fibers
or paper in a matrix bonded by cement, magnesia cement, colloidal
silica, colloidal alumina, potassium silicate, sodium silicate or
other inorganic binders.
[0019] Preferably, an adhesive is applied either to the back of the
strip 32 or to the groove 30 in the core 12 to insure good bonding
of the strip 32 to the core. Preferred glues or adhesives are of
the potassium or sodium silicate type. One such glue is sold under
the trade name Skamol S-glue available from Skamol A/S. Other
suitable glues include #760 Adhesive available from Vimasco Corp.,
and Foster Fibrous Adhesive 81-27 available from Foster Products
Corporation. Typically, such glues or adhesives are effective at
temperatures up to 800.degree. F. or higher.
[0020] FIG. 6 illustrates another embodiment of the invention,
where the core 36 is formed with grooves and reinforcing strips 38
on both the front and rear faces of the core. Specifically, FIG. 6
illustrates reinforcing strips 38 on the front face 40 of the core
36, and similar strips 38 (in dotted line) on the rear face of the
core, with the strips 38 arranged in a laterally offset
configuration on respective opposite faces of the core. It will be
appreciated that the strips 38 on opposite faces of the core may
also be aligned on the front and rear faces, i.e., each pair lying
in a single plane extending through the door, parallel to the side
edges and stiles 42. Such an arrangement would appear as shown in
FIG. 1. FIG. 6 also illustrates the stiles 42 and rails 44 in
exploded form, showing the separate stile components 46, 48 and
rail components 50, 52.
[0021] It is also possible, but not necessarily preferred, to
extend the reinforcing grooves and reinforcing strips beyond the
core and into the upper and lower rails, as shown in FIG. 7. In
this alternative embodiment, the core slab 54 is identical to the
core slab shown in FIG. 6, but grooves for the reinforcing strips
56 have been extended into the upper and lower rails 58.
Specifically, extended groove components 60, 62 have been formed,
respectively, in the rail components 64, 66 in order to accommodate
the extended-length reinforcing strips 56 on one or both faces of
the core slab. Here again, the strips 56 on opposite faces may be
aligned or laterally offset. The stiles 68 including components 70,
72 remain as in the previously described embodiments.
[0022] It is also within the scope of this invention to orient the
reinforcing strips horizontally across the door between the side
edges, i.e., parallel to the top and bottom of the door. The strips
could also be incorporated in one or both sides of the door in
aligned or offset arrangements as described above. The strips could
also extend into the stiles along the side edges if desired.
[0023] In a typical door construction, an outer skin (not shown)
comprised of wood, metal or plastic material is applied over the
core and over the reinforcing strips.
[0024] Incorporation of the reinforcing strips 32, 38 or 56 into
the door core has been found to eliminate or minimize the problem
of core cracking during fire tests while also providing sufficient
strength to resist the hose stream test following a fire test.
[0025] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
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