U.S. patent number 3,697,633 [Application Number 05/056,832] was granted by the patent office on 1972-10-10 for structural core.
Invention is credited to Howard M. Edgar.
United States Patent |
3,697,633 |
Edgar |
October 10, 1972 |
STRUCTURAL CORE
Abstract
A structural core is formed by filling a rigid frame with an
expanded synthetic polymer composition which may include fillers
and which is adhesively secured to the frame. The resultant foam
filled frame is then sliced to form panel cores. Finished panels
are made by laminating panel faces to one or both sides of the
core, or by painting, or otherwise treating the panel core. In one
embodiment, the frame may be built up of a plurality of frame
members with removable spacers to permit sawing of the foamed
material without sawing the frame. The cores and panels thus
constructed are useful in doors, walls, floors, roofs, etc. in
buildings and in furniture and other structures outside the
building industry. Reinforcing, electrical conductors, plumbing,
etc. may also be built into the cores.
Inventors: |
Edgar; Howard M. (Tustin,
CA) |
Family
ID: |
22006825 |
Appl.
No.: |
05/056,832 |
Filed: |
July 21, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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600897 |
Dec 12, 1966 |
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Current U.S.
Class: |
264/45.3; 156/78;
156/245; 156/264; 264/45.4; 264/46.5; 264/158; 428/317.5; 52/220.2;
52/309.4; 156/79; 156/254; 264/DIG.32; 264/51; 428/157 |
Current CPC
Class: |
B29C
44/5654 (20130101); B29C 44/1271 (20130101); B29C
44/58 (20130101); B29L 2031/10 (20130101); Y10T
156/1075 (20150115); Y10T 428/24488 (20150115); Y10S
264/32 (20130101); Y10T 428/249984 (20150401); Y10T
156/1059 (20150115) |
Current International
Class: |
B29C
44/58 (20060101); B29C 44/02 (20060101); B29C
44/12 (20060101); B29C 44/34 (20060101); B29C
44/56 (20060101); B29d 027/04 (); B29h 007/20 ();
B32b 031/18 () |
Field of
Search: |
;156/39,43,77,78,242,245,254,264,79 ;264/41,45,58,51,158,272 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Burnett; Robert F.
Assistant Examiner: Moxon, II; George W.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of my Pat. application Ser. No.
600,897, filed Dec. 12, 1966, entitled STRUCTURAL CORE AND METHOD
OF MANUFACTURE, allowed Apr. 22, 1970, now abandoned.
Claims
I claim:
1. The process of producing a structural core, said process
comprising the steps of:
providing a rigid frame having connected sides located in a pattern
corresponding to the outline of the completed structural core, said
frame having a height substantially greater than the thickness of a
to-be-completed structural core and an open interior;
filling the interior of the frame with a lightweight expanded
polymer composition material capable of adhesively attaching to the
interior of said frame by injecting an expandable polymer
composition into said frame and
allowing said composition to expand and set to a final, rigid
condition; and
slicing the resultant unitary structure into a plurality of
structural cores by cutting it in parallel planes so that each core
includes a border of part of said frame and a quantity of material
adhesively bonded to said part of said frame;
said rigid frame being so constructed that the surface area of the
frame in contact with the resin in a structural core is small
compared with the surface area of the foam when the filled frame is
so cut.
2. The process of claim 1 further including the preliminary step of
assembling the frame from a plurality of frame members, each of
which frame members defines the exterior configuration of the
desired resultant structural core.
3. The process of claim 2 further including the placement of
spacers between the frame members so that the frame members are
spaced from each other during the filling step and including the
removal of the spacers after the filling step and prior to the
slicing step.
4. The process of claim 1 wherein said frame is composed of unitary
panels, each of which defines a side of said frame and said panels
are cut during said slicing.
5. A process for manufacturing structural cores comprising the
steps of:
providing a rigid frame having an external configuration
corresponding to the external configuration of the desired
structural cores, a height equal to at least a plurality of
thicknesses of the desired structural cores and a substantially
open interior;
filling the open interior of the frame with a lightweight expanded
polymer composition by injecting an expandable polymer composition
into said frame which when set will be adhesive bonded to the
interior surface of the frame and
allowing the polymer composition to expand and set to a rigid
condition; and
slicing the expanded polymer filled frame into a plurality of
structural cores by cutting the expanded polymer filled frame into
a plurality of panel-like units having a rigid border which is that
part of the frame cut from the frame surrounding the expanded, set
polymer composition in the interior;
said polymer composition being adhesively bonded to the interior of
said rigid borders and said rigid frame being so constructed that
the surface area of the frame in contact with the resin in a
structural core is small compared with the surface area of the foam
when the filled frame is so cut.
6. The process as defined in claim 5 wherein the expanded polymer
composition contains at least one material selected from the group
consisting of dye, pigment, filler, fire retardent material,
reinforcing fibers and nucleating particles.
7. The process as defined in claim 5 wherein the frame includes
means defining at least one opening which is not filled with
expanded polymer for forming passageways through the structural
cores sliced from an expanded polymer composition.
8. The process as defined in claim 7 further comprising the step of
positioning electrical conductors in said frame, said conductors
being so constructed and arranged as to be substantially surrounded
by the expanded polymer composition and to form at least a pair of
individual electrical conductors in the structural cores sliced
from the expanded polymer filled frame.
9. The process as defined in claim 7 further comprising the step of
positioning a plurality of plumbing elements in said frame such
that when the expanded polymer filled frame is sliced the
structural cores formed thereby include at least one plumbing
element adapted for use in connection with a plumbing fixture.
10. The process as defined in claim 5 further comprising the step
of positioning electrical conductors in said frame, said conductors
being so constructed and arranged as to be substantially surrounded
by the expanded polymer composition and to form at least a pair of
individual electrical conductors in the structural cores sliced
from the expanded polymer filled frame.
11. The process as defined in claim 5 further comprising the step
of positioning a plurality of plumbing elements in said frame such
that when the expanded polymer filled frame is sliced the
structural cores formed thereby include at least one plumbing
element adapted for use in connection with a plumbing fixture.
12. The process as defined in claim 5 further comprising the step
of positioning at least one reinforcing member in said frame, said
member being so constructed and arranged as to be substantially
surrounded by said expanded polymer composition and to form a
reinforcing member in the structural cores sliced from the expanded
polymer filled frame.
Description
The technology of foamed or expanded plastics is well developed.
Most thermoplastic or thermosetting resins can be expanded in
volume to create cellular structures which resemble fine honeycombs
or masses of tiny hollow spheres fused together. Foaming is
conventionally accomplished by mechanical frothing, dissolving a
gas or low boiling point liquid in the resin, or by incorporating a
foaming or blowing agent which will release an inert gas in the
resin when the temperature is increased. Many adaptations and
variations of these techniques are known.
The inclusion of a great variety of fillers, pigments, reinforcing
materials, and other solid materials in foamed resins is also well
developed. By the use of appropriate fillers, pigments, etc. a
great variety of foamed plastics having many desirable structural,
physical and aesthetic characteristics can be obtained.
Among the more common foamed plastics are the foamed urethanes.
Urethane foams are cellular plastics formed by an isocyanate and a
polyol reacted in the presence of catalysts and usually in the
presence of several control agents and boiling agents. By varying
the ratio of raw materials for the foaming conditions, a broad
spectrum of end properties may be produced. Polyols useful in
urethane foam production are polyethers such as the propylene oxide
adducts of sorbitol, sucrose, diamines, pentaerythritol and methyl
glucoside. Blowing agents such as carbon dioxide produced by the
reaction of water with isocyanate, fluorocarbon-11, and methylene
chloride are commonly used. Widely used catalysts include tertiary
amines in combination with stannous salts. Additives such as fire
retardant agents, extenders, dyes, colorants, nucleating agents
such as talc or carbon black and special purpose additives are
commonly used.
Polystyrene foams and foamed vinyl resins, foamed polyethylene and
polypropylene, phenolic foams, epoxy foams, foamed silicones and
cellular cellulose materials are also well known.
There are many patents and publications available which discuss
foamed systems of this type. The following publications are
incorporated by reference as exemplary of sources of additional
information regarding the above and other foam systems: MODERN
PLASTICS ENCYCLOPEDIA, 1967, published September 1966, Volume 44,
No. 1A, McGraw Hill, New York; "A New Look in Plastics in
Building," MODERN PLASTICS, 42, 108, March, 1965; "Chemistry and
Flame Retardancy of Rigid Urethane Foam," MODERN PLASTICS, 42, 197,
January, 1965; "Formation of Cellular Plastics," BRITISH PLASTICS,
38, 552 (September, 1965); and Flory, PRINCIPLES OF POLYMER
CHEMISTRY, George Banta Company, Menasha, Wisconsin, 1953 (5th
printing, 1966).
The filling of interior voids with foam synthetic polymer
compositions is also well known in the prior art. This technique
provides a very satisfactory structural member. Relatively thin
walled structures can be made firm and rigid while maintaining
lightness and thermal insulating qualities. However, the previously
taught individual foaming of structural members has many
disadvantages. In relatively thin structural cores, a large
unsupported side area is provided. Foaming produces large pressures
and very rigid support must be provided if the sides are to be
undistorted.
Furthermore, if foaming is completed after the sides are in place,
as is conventional in the prior art, each of the structural members
must be individually handled. Also, one end must be closed after
foaming is complete.
Among the more serious problems of the prior art are those problems
resulting from the incomplete or improper filling of a form or mold
in which the surface area of the form is very high compared with
the volume of foam produced. There is a distinct tendency for the
foam either to leave large voids adjacent the surfaces of the form
or to adhere to portions of the surface thus causing distortion of
the foam and unequal filling of the foam or mold.
These and other serious problems are overcome by the present
invention.
According to this invention, structural cores are produced by
filling a rigid frame made up of members forming sides positioned
in a pattern corresponding to the outline of the desired completed
structural core. The frame has a height substantially greater than
the thickness of the structural core or cores to be formed and has
an open interior. The interior of the frame is filled with a
lightweight expanded polymer composition material, which may
include fillers, coloring materials, additives, etc., as previously
alluded to, which adhesively attaches to the interior of the frame.
The polymer composition or foam material is allowed to set or cure
to a rigid condition.
The entire foam filled frame structure is then sliced into a
plurality of cores. This usually is done by cutting the foam filled
frame bun along relatively parallel planes so that each core
includes a border of the frame and a quantity of foam filament
material adhesively bonded to the frame. Of course, asymmetrical
panels may be formed by cutting the foam filled frame bun along
relatively nonparallel planes but in a manner in which the core
thus formed includes a border of the frame to which the foam is
adhesively bonded.
In this process, the expansion of the foam is toward the upper side
of the structural frame, which is usually open. The frame is so
constructed that the surface area in contact with the resin in any
core formed from the frame is small compared with the surface area
of the foam core when cut.
The edges of the frame which form the borders of the core are
normally of a relatively heavy material such as wood, metal, high
density resin, etc., so as to provide a degree of structural
strength along the borders of the core. The faces of the core are
preferably then covered by laminating a thin side panel to one or
both sides of the core to form a finished structural member.
Lamination is not always required since the core may be used as a
structural member without further treatment or with only painting,
varnishing, dying, or other treatment.
One of the significant advantages and very important commercial
advantage of the present invention is that the foaming can be
accomplished in a very large frame which, when sliced, results in a
multiplicity of finished structural cores. The time and labor in
handling the materials is very greatly reduced as compared with the
construction of similar cores using the techniques of the prior
art.
One of the features of this invention is that a plurality of
structural cores can be produced according to the method of this
invention more rapidly and more economically than is possible using
conventional techniques. These cores may be used for a large
variety of applications. Among the more obvious applications and
uses of the structural cores of the invention are the use of such
cores in doors, movable partitions and panels, furniture tops,
sides, etc., and in other applications where structurally strong
but lightweight panels are desirable.
According to one of the important features of the invention, the
frame is so constructed and arranged that when the foam filled
frame bun is sliced each slice constitutes the core of a major
element of a building. Such major elements include walls, ceilings,
roofs, floors, permanent and temporary partitions, or portions
thereof. These structural units may be preformed with interior
reinforcing elements, doors, windows, plumbing, electrical
conduits, etc. so as to permit the production of finished or
semi-finished structural units from an appropriately constructed
foam filled frame simply by slicing the frame. The substantial
savings in time, material and labor costs which may be accomplished
through the inventive process are apparent.
Pressures resulting from the expansion of the foam in the frame are
largely released through the expansion of the foam upwardly from a
relatively large interior portion of the frame. This eliminates or
reduces the need for heavy bracing to overcome foaming pressure.
Where very large and deep foam filled frame buns are formed, some
bracing is usually required but the cost of the bracing is
substantially less expensive than is required in prior art
techniques.
Several other features and advantages of the structural cores of
the invention and the inventive process will be apparent from the
specification and claims which follow and from the drawings to
which reference is made.
FIG. 1 is an isometric view showing a step in the process of
forming a structural core according to this invention; the step
illustrated being the filling of the frame with a foaming synthetic
polymer composition.
FIG. 2 is an isometric view, with certain portions broken away,
showing an alternative embodiment of the invention wherein a
plurality of individual frame or border members are built up into a
frame into which the polymer composition is foamed.
FIG. 3 is an isometric view, with certain surface parts broken
away, of a finished panel structural member which is made up by
laminating sides on a core made according to the processes
illustrated in FIG. 1 or FIG. 2.
FIG. 4 is an enlarged transverse section of a plurality of frame or
border members, such as are shown in FIG. 2, showing the manner in
which they are stacked and spaced prior to being filled with foamed
polymer composition as, for example, illustrated in FIG. 1.
FIG. 5 is an enlarged partial vertical section showing two adjacent
frame members and a spacer of the type illustrated in FIG. 4.
FIG. 6 is an isometric view of a foam filled frame bun showing
interior reinforcing elements and an opening which forms a window
opening in a finished wall; the frame bun being particularly
adapted to being sliced into walls or wall units.
FIG. 7 is a cross sectional view of a panel formed from the foam
filled frame bun of FIG. 6, including laminated skins on both sides
of the core.
FIG. 8 is a plan view of a wall unit formed according to this
invention and the process described herein including an opening for
a door and door framing and electrical conduit suitable for forming
a portion of a building electrical circuitry system.
FIG. 9 is a cross section in enlarged scale of a portion of the
panel shown in FIG. 8 illustrating a simplified method for
attaching electric wiring to the conduitry built into the core.
FIG. 10 is a cross sectional view of a portion of a core of the
type shown in FIG. 8 illustrating one method for connecting a
switch box to the conduitry formed into the core.
FIG. 11 is a partial vertical section of a foam filled frame bun
according to this invention including built in plumbing elements,
the dashed lines indicating the planes along which the bun is to be
sliced.
FIG. 12 is a partial elevational view of a core cut from the foam
filled frame bun shown in FIG. 11 illustrating the relative
placement of the plumbing elements therein.
FIG. 13 is a plan view of a structural core member cut from a foam
filled bun for use in the manufacture of a curved roof panel.
FIG. 14 is a perspective view of the panel illustrated in FIG. 13
shown formed in a hyperperabolic configuration, the dashed lines
indicating a rectangular space partially occupied by the curved
structural core.
The structure and process of the invention is most easily described
with reference to the drawings. In the embodiment of FIG. 1, a
frame 10 comprising a top 12, bottom 14, left side 16, and right
side 18, is provided. The rectangular configuration of the frame 10
is illustrative and, of course, results in the desired
configuration of structural core which is rectangular in external
configuration. Should a different shape of core be desired, the
frame 10 is arranged in such a manner as to define the lateral
limits of the finished structural core. Furthermore, while butt
corner joints are shown, it is equally clear that any conventional
type of structural corner joint can be applied.
In an exemplary process, flush door cores are preferably produced
from the structural frame 10, and thus the interrelationship of the
rails is that which is conventional for flush doors.
The frame 10 is open at the top and is closed at the bottom. The
bottom closure may comprise merely the placing of the frame 10 upon
a flat surface, or may comprise securing, temporarily or
permanently, a bottom to the frame. The bottom may be a rigid sheet
or panel member or it may simply be a paper or fabric for temporary
use. The bottom may be formed of any convenient, inexpensive
material and may desirably be of a nature as to prevent the
sticking of the foamed or expanded polymer composition to the
supporting base.
The height of the frame 10, as illustrated in FIG. 1, is at least
as thick as a plurality of thicknesses of the structural cores
which will be produced therefrom by slicing the foam filled frame
bun formed according to the process. After the frame 10 is produced
and closed, if desired, and placed on a supporting surface, the
interior of the frame is filled. The step of filling comprises
inserting by spraying, injecting, pouring, or by other means, any
convenient foamable or expandable synthetic polymer composition
which is suitable in physical characteristics for the purpose to
which the structural core will be put.
In an illustrative embodiment, a conventional foam depositing
nozzle 20 is illustrated as depositing lightweight material 22
through the open top of the frame 10 to fill the entire interior of
the frame.
The synthetic polymer composition can be an expandable
thermosetting or thermoplastic synthetic polymer composition such
as, for example, urethane, polyester, polystyrene (which may be in
the form of expandable beads) or any other expandable resinous
material. Foamed plastics as described hereinbefore and those
equivalent to such materials are generally suitable for use in this
invention.
The expanded polymer composition, when cured, preferably has a
density of from about one lb. per cubic foot to about 20 lbs. per
cubic foot for most structures. If extremely high strength and/or
high density cores are required, the density of the expanded
polymer composition may be as high as 40 or 50 lbs. per cubic foot
but for most structural purposes a density of 1.25 to 5 lbs. per
cubic foot gives adequate strength, rigidity, and desirable
structural characteristics.
Expansion of the polymer material may be induced by catalysts, heat
probes, steam, or other techniques, some of which have been
described hereinbefore.
Suitable lightweight materials, fillers, binders, reinforcing
materials, dyes, pigments, and special additives may also be
included in the expanded polymer composition. Lightweight
aggregates mixed with binders, such as polyester, epoxy and other
binders, may also be included in the polymer composition to give
the desired physical and aesthetic characteristics. The particular
material used is not critical, provided that it has a reasonable
amount of rigidity and preferably that it adhesively attaches to
the interior of the frame.
Adhesive attachment is particularly important in terms of high
strength, rigidity, and economy in manufacture. Core structures of
the prior art have been made using the "cut-and-fit" technique in
which one of a plurality of pieces of foam are carefully cut to
very precise dimensions and fitted into a carefully dimensioned
frame. Resins and bonding materials are provided to secure the
expanded polymer pieces together and to the frame. This technique
obviously requires a great deal of time, is expensive in terms of
labor, and the results are not entirely satisfactory because of the
high criticality required in cutting and positioning.
The necessary bonding between the expanded polymer in the interior
of the frame, in the present invention, is usually and is most
conveniently accomplished simply by using a polymer composition
which forms a structurally sound bond with the frame. The same
result can be accomplished, less conveniently however, by coating
the interior of the frame with an adhesive or other bonding
material or a material which when in contact with or reacted with
the expanded polymer forms an adhesive bond between the expanded
polymer and the frame. For example, the interior of the frame may
be coated with an epoxy, which forms an excellent bond with the
expanded polymer. When the expanded polymer is curing, a
comparatively high quantity of exothermic heat is generated which,
in a properly designed system, is sufficient not only to result in
the final curing of the expanded polymer but to cure the epoxy and
thus form a high strength structurally sound adhesive bond between
the expanded polymer and the frame. In most instances, however, it
is unnecessary to provide special adhesive agents on the frame
surface although preparation of the frame in the conventional
manner to form a strong bond may be recommended.
After the frame is filled with lightweight material, such as filled
or unfilled expanded polymer, the polymer is then cured. The cured
foam filled frame is then sliced into individual structural cores.
Preferably, this slicing comprises the slicing of a plurality of
relatively thin structural cores from the frame and foam material
structure. These slices are preferably planar, and are preferably
of uniform thickness for most uses. In certain wall constructions
and where particular aesthetic effects are desired, however, the
planes may be of nonuniform thickness and the slices may be cut
along relatively nonparallel planes. Thus, the cores may be wall
panel cores and may, if desired, be thicker at the bottom than at
the top. In any event, each slice forms a structural core which
contains a portion of the frame which encloses the expanded polymer
to form an edge border of the desired configuration.
The individual structural cores may be, of course, cut in any
desired thickness. Moreover, a plurality of structural cores may be
cut from a single foam filled frame bun in differing thicknesses
and in differing configurations. In most instances, the structural
cores would be cut in planes perpendicular to the axis of the frame
but this is not required and pleasing aesthetic effect and, in
certain instances, desired structural elements may be obtained by
slicing the frame at an angle with respect to the axis thereof.
Many thicknesses and styles of structural cores may be cut from a
single expanded polymer composition filled frame.
It will be also be recognized that the foam filled frame buns also
constitute an article of commerce. Thus, the expanded polymer
composition filled frame bun may be prepared at one location and
sold commercially to fabricators, manufacturers, and others for
subsequent slicing into structural cores.
One structural core of uniform thickness formed by slicing the foam
filled frame bun along parallel planes is illustrated in FIG. 3 at
24. A plurality of the structural cores 24 are produced from a
single foam filled frame bun comprising the frame 10 and the foam
material 22. Slicing is accomplished by means of a conventional
band saw, when the frame is made of wood or by using hardened tooth
band saws adapted to cut the particular material of which the frame
is constructed.
After the individual structural cores, such as illustrated at 24,
are produced, they may be covered with a suitable cover sheet or
panel. In the case of the structural core 24, FIG. 3, door skins 26
and 28 are laminated on the surfaces of the core. Depending on the
configuration and thickness, the structural cores can be used for
the mass manufacture of lightweight panels for many uses. The
panels may be used as table tops, counter tops, furniture panels,
and any other items which have laminations of expanded polymer
composition with veneers, metal plates, sheets, or other coverings
including shaped or flat panels. The structural member 30, which is
specifically a door, falls within this class of structures. The
door skins or other structural core coverings can be secured by any
convenient means. Adhesive bonding is preferred, however. In the
example of the structural member 30, since it is flat rather than
contoured, a plurality of such structural members can be placed
together and the door skin secured thereto in stacked multiple
relationship, to further save labor and press time. It will be
understood that the structural member 30 merely exemplifies the
invention and that the core need not be of uniform thickness, or
rectangular configuration. Curved sawing and a curved frame will,
of course, produce a core having at least one curved exterior
surface. Curved or flexible panels can be laminated to such
surfaces using conventional techniques.
FIGS. 2, 4 and 5 illustrate an alternative embodiment of the
invention. In this embodiment a frame, generally indicated at 32
and corresponding to the frame 10 of FIG. 1, is made up of a
plurality of frame or border members. The border members making up
the frame 32 are indicated at 34, 36, 38, 40, 42, 44, 46 and 48.
Each of the border member 34-48 has an appropriate external
structure configuration defining edge or means.
In the structure shown, top, bottom and side border elements are
provided so as to create a structural core of suitable nature and
of desired configuration so as to be usable as the core of a flush
door. Other outlines and configurations than the rectangular
configuration illustrated can be provided, depending upon the needs
and requirements of the finished panel or core.
In the frame 32 the structural cores are necessarily planar, as
compared to the curves or otherwise nonplanar structural cores
which can be cut from the frame 10. An appropriate number of border
members are used in accordance with the process requirements, the
size of the equipment available, the number of units required, and
other economic and technical considerations. By appropriate
technique, any reasonable number can be used.
In order to maintain the frame or border members 34-38 in properly
aligned stacked relationship, combined guide and spacer means 50
are provided. The combined guide and spacer means comprise a
structure of T-shaped cross section with head 52 arranged to
embrace the exterior of adjacent frame members. For example, in
FIG. 5 the head 52 embraces frame members 42 and 44 so as to
maintain them in vertical alignment. Guide and spacer means 50
extend all the way around the frame 32. The combined guide and
spacer means are preferably of unitary structure so as to maintain
the frame members in appropriate stacked position. However,
individual strips can be used so long as the frame assembled from
the frame members and combined guide and spacer means is properly
and evenly stacked or held in stacked relationship. The upright 54
of the T's, one of which is shown at 50, extends inwardly between
the rails of the adjacent frame members. In FIG. 5 it extends
inwardly between the rails of frame members 42 and 44. The amount
of spacing produced by the uprights 54 is preferably equal to the
kerf produced by the slicing means when the frame is sliced into
individual structural cores.
As is illustrated in FIG. 4, a combined guide and spacer means 50
is positioned between each adjacent pair of frame members. The
resultant structure, as shown in FIGS. 2 and 4, is quite similar to
the frame 10. After this frame is assembled, it is filled with
foamed polymer composition in the same manner as previously
described. After the foam material is set or cured so as to be
relatively rigid, although complete curing is not always required,
the combined guide and spacer means 50 is removed. In the case of
individual strips, they are simply pulled out of place. In the case
of a complete rigid structure, the structure is disconnected so
that the combined guide and spacer means can be removed.
The foam filled frame bun, in which the frame is made up of a
plurality of border elements forming the frame member 32 is then
sliced into individual structural cores. Slicing is accomplished by
sawing between the frame members so that each frame member defines
the border or outline of the desired core member. After slicing,
each of the frame members comprises an individual structural core
identical in all essential elements to the structural core 24 and
may be employed in the same way.
Through the use of the frame 32, as compared with the frame 10,
smaller pieces of material can be used, rather than employing the
large side, top and bottom structures used in the frame 10.
Furthermore, materials which are difficult to cut can be used. For
example, metal rails can be used as the border elements to form the
outline of the structural core. Since slicing occurs only between
the individual frame or border members, it is not necessary to
provide a saw capable of cutting the metal. This latter technique
has the disadvantage in that more handling is required but in
certain instances this handling may economically and technically be
justified or required. This additional handling is in the
assembling of the frame 32 and the removal of the combined guide
and spacer means 50 and, by the use of appropriate jigs and
assembling devices, can be accomplished rather efficiently,
although more time and expense is usually involved than is involved
in the preparation of structural cores using frames of the type
illustrated in FIG. 1.
FIGS. 6 and 7 illustrate the application of the process and
techniques of this invention to the construction of whole or
partial walls or wall units. According to this embodiment of the
invention, a frame generally indicated at 60 is constructed of ends
62 and 64, a bottom 66 and a top 68. The frame may be constructed
of several unitary pieces of wood, as shown, of high strength
laminated board, of metal, or of a plurality of border pieces, as
illustrated in FIG. 2. Interiorly of the frame, a plurality of
reinforcing members 70, 72 and 74 are provided to give added
strength to the core structures when finally finished. Between
reinforcing elements 72 and 74 lateral interior structural elements
76 and 78 define the top and bottom of an opening which, in the
finished core, will comprise a window opening. The structural
elements 76 and 78 along with the appropriate portions of the
reinforcing members 72 and 74 comprise means for defining an
opening in the interior of the frame which is not filled with the
expanded polymer composition.
While only one opening is illustrated in FIG. 6, it will be
understood that a plurality of such openings may be constructed.
The openings may be constructed in conjunction with the reinforcing
members 72 and 74, or other types of reinforcing members. The
openings may, however, also be constructed using simply structural
elements, in the form of boards or panels, or metal sheets or
plastic sheets, etc., analogous to elements 76 and 78 of FIG. 6
which provide no reinforcing for the overall core structure.
Likewise, the openings may be useful as windows, doors, or for
other passageways useful or necessary in residential, commercial or
industrial buildings, or for other purposes.
FIG. 7 illustrates in cross section a panel completed using a core
cut, as described previously, from the foam filled frame bun
illustrated in FIG. 6. The panel comprises a core having portions
formed from the synthetic polymer composition filled areas 80, 82,
84, 86 and 88 of the foam filled frame bun of FIG. 6. The faces of
the core are covered with skins 90 and 92. These skins may be of a
decorative panel, a structural material, or an unfinished material
suitable for being finished in a building. In certain instances, it
may be desirable to leave one or both faces of the core unsheathed
by skins and in certain instances it may be only necessary or
desirable to paint or otherwise decorate the surfaces of the core.
In the ordinary instance, however, substantially greater structural
strength is accomplished by adhesively laminating, or otherwise
securing, skins to the surfaces of the core and the skins can be
selected greatly to enhance the aesthetic value of the finished
panel.
FIGS. 8, 9 and 10 illustrate a panel and portions thereof equipped
with electrical conductors and fixtures. According to this
embodiment of the invention, cores are formed using the methods and
techniques and materials as previously described. In addition,
however, conductive strips are formed into the foam filled frame
bun and appear in the finished core. These conductive strips or
conductive elements are then suitable for use in distributing
electricity throughout a building constructed from cores and panels
so formed.
FIG. 8, which is an elevational view of such a panel, designated
generally at 100, includes a bottom 102, a top 104, and ends 106
and 108. A doorway is defined by structural members, which in the
panel constitute a door frame 110 and 112 at the respective sides
and 114 as a header.
In addition, two sets of electrical conductors are formed into the
panel for use in distributing electricity to outlets, switches,
etc. in the panel. One set of conductors 116 and 118 is so arranged
as to provide a convenient source of electricity for electrical
outlets. One conductor 120 is so arranged as to provide a
convenient means for switching. In the other set, conduits 122 and
124 are conveniently positioned to permit the mounting of
electrical outlets in the panel while the conductor 124 is
conveniently located to permit switching.
These electrical conductors may be in the form of sheets of
conducting material, such as copper, vertically positioned in the
frame and about which the foam flows so as entirely to encompass
the conductors. In this case, it is desirable to perforate the
sheets with numerous openings of suitable size to permit the
expanded polymer material to flow freely through and about the
conductors. In this embodiment of the invention, the expanded
polymer composition should be electrically insulating. This will
result, of course, in the requirement that certain classes of
fillers, which are highly electrically conductive, be omitted. The
electrical conductors may, however, constitute simply wires,
insulated or uninsulated, appropriately positioned and spaced in
the frame around which the expanded polymer composition flows. If
insulated wires or other conductors are used, the expanded polymer
composition need not be electrically insulating, although this may
be a desirable characteristic. Simply for purposes of illustration,
the conductors are shown as sheets of conductive material.
These sheets of conductive material may be connected to the
remainder of the building or house circuitry as illustrated in FIG.
9 in which a plurality of wires 128, 130 and 132 extend through a
border element, such as top 104, and are secured to the conductors,
for example conductors 116, 118 and 120, respectively. The
connection between the wires and the conductors may be made by any
conventional or desired means, bolts 134, 136 and 138 being
illustrated simply for convenience. The connection can be made by
simply augering or cutting out the polymer material from around the
ends of the respective conductors. The connections may be potted
using conventional polymeric resins following completion of the
connections, if desired. Foamed or expanded polymer potting
compositions may likewise be utilized.
Fixtures, such as switch 140, may be connected in any desired
manner, the embodiment of FIG. 10 being merely illustrative of one
simple method of connecting such fixtures. In this embodiment, a
portion of the expanded polymer composition is dug or augered out
of the core, as illustrated at 142. The switch box is provided with
sharp teeth 144 and 146 on one side and 148 and 150 on the other
side which extend outwardly and engage the conductors 118 and 120
to form electrical connections therewith. These teeth are then
connected to the switch elements and provide for making and
breaking an electrical circuit between the conductor 118 and the
conductor 120, for example. The core may desirably be sheathed with
skins 152 and 154 in the conventional manner.
Of course, many conventional methods of making electrical
connection and many methods especially designed to make electrical
connection with the conductors may be used without departing from
the scope of this particular facet of the invention. What is
significant in this invention is that the conductors are factory
built into walls or wall units. Since this can be done on a mass
production basis and using highly specialized jigs and other
machinery, there is an enormous saving of time and effort, as
compared with field installation of wiring. Moreover, by
appropriate design, all essential electrical wiring can be built
into cores and panels formed from the cores so that only nominal
hookup is required in the field. Where the panels and cores are
used for floors, ceilings, roofs, and for exterior walls, for
example, outlets for lights, appliances, heating, and other
electrical using devices may be built into the panel, depending
upon the particular needs, simply by positioning electrical
conductors in the frame at desired intervals and in desired
configurations prior to the filling of the frame with the expanded
polymer composition.
FIGS. 11 and 12 illustrate another advantageous feature of this
invention which may be used alone or in conjunction with the
feature illustrated in FIGS. 8, 9 and 10. In this embodiment of the
invention, roughed in plumbing elements are built into panel cores
and panels. FIG. 11 illustrates a foam filled frame bun prepared
for slicing along the dashed lines. When so sliced, four cores are
formed from this particular frame. As illustrated, each of the
cores will include hot and cold water piping and drain piping. As
illustrated in FIG. 11, for example, one portion of a frame 160 is
shown. The frame is filled with a foam of the type described
illustrated at 162. Positioned in the frame, with or without
positioning brackets not shown, are four sets of cold water pipes
illustrated at 164, 166, 168 and 170. Also shown, in dashed line,
are four sets of hot water pipes 172, 174, 176 and 178 and eight
sets of drain pipes identified as 180 and 182 in the top core
portion, 184 and 186 in the second core portion, 188 and 190 in the
next core portion, and 192 and 194 in the bottom core portion. A
portion of a core corresponding to the top core portion is
illustrated in FIG. 12. Such a core would result from the slicing
of the foam filled frame 160 along the top dashed line.
As illustrated, this core has a border 160 including a top 160' and
a bottom 160" and is filled with an expanded polymer material 162
as in FIG. 11. The cold water pipe 164 has a capped outlet 196
facing outwardly from the sheet and another capped outlet 198 which
would open to the other side of the core. In like manner, the hot
water pipe 172 has a capped outlet 200 on the side of the core
shown with another capped outlet 202 opening to the other side of
the core. Drain pipe 180 opens to the front side of the core while
a similar drain 182 has an outlet opening to the other side of the
core. The core may, of course, be sheathed with a skin or otherwise
coated or treated as previously described. In the illustrated
embodiment, the water pipes are offset vertically with respect to
each other. By incorporating somewhat more complex plumbing into
the frame and using appropriate positioning supports, etc., any
desired arrangement of plumbing outlet can be achieved. When the
desired plumbing arrangement is achieved in the frame, then the
foam filled frame bun is sliced along predetermined planes. Where
necessary, the foam is augered out to expose the plumbing, the caps
are removed, and connections are made in the usual manner or by
using special fittings.
By careful design and placement, all or a substantial portion of
the electrical conductors and plumbing may be prebuilt into wall
panels at the factory. This, of course, results in very substantial
savings in cost as well as in higher quality walls, greater
precision in placement of fixtures and plumbing outlets, higher
dependability in production and the avoidance of expensive and
inefficient field labor. Another advantage will be apparent with
respect to the inclusion of plumbing in the expanded polymer. Water
hammer is reduced, since the plumbing is secured at all points in
the wall and, even where water hammering is not avoided, the sound
and vibration commonly resulting from this undesirable phenomena
are greatly reduced and attenuated.
It will be apparent from the preceding discussion that the
structural core members formed according to the process of this
invention may be manufactured in an enormous variety of sizes,
shapes and configurations and that the expanded polymer composition
may be of any of a great variety of densities, textures, colors,
etc. and may have physical properties of many types, according to
individual desires or requirements. For walls intended to bear very
heavy loads, it may be desirable to slice frames filled with high
density, high crush strength reinforced polymer composition to form
structural cores. These cores may then be used alone or with one or
both surfaces covered with skins. The structural cores may be
stressed or covered with skins to provide additional strength,
covered with high density building board for high acoustical
attenuation, with high quality paneling for specialized
construction needs, or with low cost paneling for construction
where economy is the dominating factor. The skins may be fastened
to the structural cores in any desired manner but preferably are
adhesively secured thereto.
In addition, structural cores cut from frames filled with selected
expanded polymer compositions may be curved, twisted or otherwise
formed after the slicing operation. One exemplary embodiment of
such a technique is illustrated in FIGS. 13 and 14. The structural
core, identified at 204, is manufactured in the usual way and
includes border elements 206 and 208 on opposing sides and end
elements 210 and 212 on one end and 214 and 216 on the other end.
The end border elements 214 and 216 are joined at one end with the
respective sides 206 and 208 and converge inwardly toward the
center of the structural core and are joined end to end on the
longitudinal center line of the structural core. End elements 210
and 212 are likewise joined end to end along the longitudinal
center line of the structural core and at the opposite ends to the
respective sides 206 and 208.
As illustrated in FIG. 14, diagonally opposite corners, formed by
the junction of border elements 206 and 214 and by border elements
208 and 212, respectively, are raised or supported and when the
remaining opposite diagonal corners are permitted to sag or are
depressed so that the structural core occupies a portion of a
rectangle indicated in dashed lines in FIG. 14, four corners of
which are defined by the corners of the panel. The panel is then
curved in a generally hyperbolic fashion. Thus, while the
structural core forms a polygon with two parallel sides but with
nonparallel end elements, the hyperbolically curved structural
core, in outline, defines a rectangle. The structural core may be
fixed in the hyperbolically curved configuration by covering it
with appropriately curved skins or by covering it with skins which
are flexible but which set to a rigid condition. For example, a
structural core was constructed according to the techniques
described, formed into the hyperbolic configuration illustrated in
FIG. 14, and both sides of the structural core were skinned with a
glass fiber reinforced polyester.
Since the structural cores of this invention may be made in almost
any size, it is possible and convenient to form the roof of an
entire building or a portion of a building by constructing a frame
of appropriate size, slicing the foam filled frame to form the
structural cores and configuring the structural cores in the from
illustrated in FIG. 14. The hyperbolically configured roof panel
may be preformed and transported to the building site or the
structural core, in the flat configuration illustrated in FIG. 13,
may be transported to the building site and then formed into the
hyperbolically curved panel as illustrated in FIG. 14.
Many other configurations are also possible, the illustrated
configuration being merely exemplary of the flexibility allowed to
a designer or architect through the use of the structural cores and
panels formed therefrom.
While the principles and procedures used in the process of this
invention and the advantages of the structures and the process of
the invention are clearly described in the preceding discussion,
the following example indicates the specific application of these
principles to the formation of particular structures.
A two pound per cubic foot density cured expanded polymer
composition filled frame bun was prepared according to the
following technique and using the materials indicated. A
commercially available polyol, produced by Reichhold Chemicals,
Inc., consisting essentially of a propylene oxide-water adduct
having a molecular weight of about 400-500 and containing a
fluorinated hydrocarbon as a foaming agent and a tertiary aliphatic
amine as the catalyst was mixed with a commercially available
isocyanate also produced by Reichhold Chemicals, Inc. in a ratio of
45 parts of polyol to 55 parts of isocyanate. The mixing time was
40 seconds, the cream time was 1 minute, 40 seconds, the string gel
time was 5 to 6 minutes, the full rise time was eleven minutes and
the tack free time was eleven to twelve minutes.
This composition filled a frame which had been constructed of 3/4
inch thick plywood. The expanded resin composition formed an
adhesive bond with the plywood which was of equal or greater
strength than the body of the expanded polymer. A large number of
expanded polymer filled buns in a great variety of shapes and sizes
were made in this general manner.
After the polymer had cured, usually by setting at least overnight,
the expanded polymer composition filled frame was sliced on a band
saw to form structural cores in which a portion of the frame formed
a border extending around the polymer filled interior. These
structural cores were, in most cases, sheathed on both sides with
1/4 to 3/4 inch thick plywood.
The structural cores varied in thickness from less than one inch to
five or six inches, or more. Structural cores four to six feet in
width and up to twelve feet in length were formed from foam filled
frames of like dimension. Where desired, a plurality of structural
cores were adhesively bonded together using conventional
techniques. A skin of plywood was then adhesively bonded on both
sides of the combined structural core assembly to form panels of
any desired shape and configuration.
Where the quantity of production contemplated justifies, the buns
may be formed with any exterior configuration and in virtually any
size so as to avoid the necessity for handling and adhesively
bonding the individual structural cores. The only contraint on the
size in which the structural cores can be constructed appears to be
the constraint imposed by the size of the saw available. In the
foregoing examples, a band saw was used for slicing the buns. The
band saw available was a pilot plant type saw and foam filled frame
buns having a width of greater than about six feet could not be
sliced. Using a larger band saw, however, the slicing of expanded
polymer composition filled frame buns of 12 feet in width and 60
feet or more in width is planned.
Panels constructed by sheathing both sides of the structural cores
or both sides of assemblies containing a plurality of structural
cores formed as described have been used in the construction of
buildings. It is thus possible to slice an entire building wall out
of a single expanded polymer composition filled frame bun. The
wall, moreover, may include not only windows and doors where
required but reinforcing and, if desired, electrical and plumbing
elements. The advantages of the inventive process and the
structures of the invention in the mass production of buildings
will be apparent. Of course, smaller panels, such as for doors,
movable partitions, etc., are very easily fabricated using the
inventive techniques.
Where high strength is required, higher density expanded polymer is
used to fill the frame. Conversely, where only low strength is
required, low density expanded polymer compositions are quite
suitable. In general practice, it has been found that expanded
polymer compositions which, when cured, have densities from 1.25 to
about 5 lbs. per cubic feet are quite suitable for most building
structural uses. Where screws, nails or other frictional fasteners
are used, rather than epoxy, polyester, or other conventional
adhesives, densities of 5 to 10 lbs. per cubic foot may be desired,
although it is doubtful that the advantages resulting from these
higher densities justify the added weight and cost.
It will be clearly apparent from the foregoing discussion that
there are a great many variations and adaptations of the process of
the invention and of the structures of the invention which can be
made and which would obviously be made by one skilled in the art
without departing from the spirit and the scope of the invention as
defined in the claims which follow.
* * * * *