U.S. patent application number 09/728647 was filed with the patent office on 2004-01-29 for construction material containing expanded flexible material.
Invention is credited to Alhamad, Shaikh Ghaleb Mohammad Yassin.
Application Number | 20040018340 09/728647 |
Document ID | / |
Family ID | 46202814 |
Filed Date | 2004-01-29 |
United States Patent
Application |
20040018340 |
Kind Code |
A1 |
Alhamad, Shaikh Ghaleb Mohammad
Yassin |
January 29, 2004 |
Construction material containing expanded flexible material
Abstract
A construction material such as an insulating roofing material
is prepared by slitting a sheet of flexible material, such as
cardboard, plastic, or metal foil, to provide discontinuous slits
in spaced apart parallel lines, and then stretching the slitted
sheet to produce a three-dimensional cellular configuration. The
cells thereof are then filled with melted tar and aggregate, such
as sand, and then cooled to provide a layer of construction
material.
Inventors: |
Alhamad, Shaikh Ghaleb Mohammad
Yassin; (Riyadh, SA) |
Correspondence
Address: |
Charles E. Cates
Cates & Holloway
P.O. BOX 1532
Scottsdale
AZ
85252-1532
US
|
Family ID: |
46202814 |
Appl. No.: |
09/728647 |
Filed: |
December 1, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09728647 |
Dec 1, 2000 |
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09658595 |
Sep 11, 2000 |
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09658595 |
Sep 11, 2000 |
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08561293 |
Nov 21, 1995 |
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6117062 |
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08561293 |
Nov 21, 1995 |
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08414106 |
Mar 31, 1995 |
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08414106 |
Mar 31, 1995 |
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07806901 |
Dec 12, 1991 |
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5402852 |
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07806901 |
Dec 12, 1991 |
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07674277 |
Mar 19, 1991 |
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5097907 |
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07674277 |
Mar 19, 1991 |
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07417696 |
Oct 5, 1989 |
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5001017 |
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07417696 |
Oct 5, 1989 |
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07280317 |
Dec 6, 1988 |
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Current U.S.
Class: |
428/136 |
Current CPC
Class: |
Y10S 493/967 20130101;
Y10T 428/24314 20150115; B31D 2205/0023 20130101; B31D 1/0031
20130101; A62C 3/06 20130101; B31D 2205/0082 20130101; B21D 31/04
20130101; B65D 81/02 20130101; B21D 31/046 20130101; B31D 3/04
20130101; Y10T 83/4798 20150401; B31D 5/0065 20130101; A62C 3/0257
20130101; Y10T 83/483 20150401 |
Class at
Publication: |
428/136 |
International
Class: |
B32B 003/10 |
Claims
What is claimed is:
1. A construction sheet material comprising (a) a cellular expanded
sheet of material formed by longitudinally stretching a sheet of
flexible material having discontinuous slits in spaced apart
parallel lines, and (b) a filler material comprising aggregate and
tar filled in the cells of said cellular expanded sheet.
2. The construction sheet material of claim 1 wherein said flexible
material is cardboard.
3. The construction sheet material of claim 1 wherein said flexible
material is plastic.
4. The construction sheet material of claim 1 wherein said flexible
material is metal foil.
5. The construction sheet material of claim 1 wherein said
aggregate is sand.
6. A method of producing a construction material comprising the
steps of slitting a sheet of flexible material to provide
discontinuous slits in spaced apart lines parallel to each other,
stretching said slitted sheet to produce a three-dimensional
cellular configuration, filling the cells thereof with a mixture of
melted tar and aggregate, and subsequently cooling said material to
produce a hardened layer of construction material.
7. The method of claim 6 wherein said flexible material is
cardboard.
8. The method of claim 6 wherein said flexible material is
plastic.
9. The method of claim 6 wherein said flexible material is metal
foil.
10. The method of claim 6 wherein said aggregate is sand.
11. A method of providing a construction material comprising the
steps of producing a compact roll of a continuous sheet of
unexpanded flexible material having discontinuous slits in spaced
apart lines parallel to each other; transporting said roll in
compact, unexpanded form to a site of usage; unrolling and
stretching said continuous sheet to provide a three-dimensional
cellular material; and filling the cells of said cellular material
with a mixture of melted tar and aggregate.
Description
[0001] This application is a continuation of U.S. application Ser.
No. 09/658,595, filed Sep. 11, 2000, which is a continuation of
U.S. application Ser. No. 561,293, filed Nov. 21, 1995, which is a
continuation of U.S. application Ser. No. 414,106, filed Mar. 31,
1995, which is a continuation-in-part of Ser. No. 806,901, filed
Dec. 31, 1991, now U.S. Pat. No. 5,402,852, which is a division of
U.S. application Ser. No. 674,277, filed Mar. 19, 1991, now U.S.
Pat. No. 5,097,907, which is a division of U.S. application Ser.
No. 417,696, filed Oct. 5, 1989, now U.S. Pat. No. 5,001,017, which
is a division of U.S. application Ser. No. 280,317, filed Dec. 6,
1988.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a unique form of expandable
metal foil and to expanded metal nets made therefrom. The invention
also relates to methods and apparatus for producing the said
products, and to uses thereof, particularly in the extinguishing of
fires and the prevention of explosions.
[0003] Surface fires, such as grassland and forest fires, as well
as fires on the surface of water and on the surface of fuels in
fuel tanks, are a continuing threat to life and property throughout
the world. Over the years, numerous methods for combating such
fires have been developed. The use of water, foams, chemicals and
other quenching materials are well known.
[0004] It is also known to use blankets, mats, nets and other
sheet-like materials to smother surface fires. However, these are
heavy, bulky materials, and their use in widespread surface fires
extending over thousands of acres of land or water, are subject to
obvious limitations. Firefighting methods today are still limited
to the steps of containing the fire as much as possible until it
burns out or until changing weather conditions no longer support
the burning. There is a need for a more efficient, inexpensive
means for extinguishing fires which extend over wide surface
areas.
[0005] There is also a need for more effective ways of preventing
explosions in containers for fuels or other explosive substances.
Containers such as fuel depots, liquid petroleum gas tanks,
airplanes, ships, transport tankers, pipelines, and the like, are
at risk from explosion caused by overheating, static electricity
build up, mechanical impacts, etc. In addition to precautionary
measures such as avoiding the above causes, a more recent approach
to the problem has involved placing in the container a quantity of
filling material in the form of a honeycomb shaped metal
net--either in sheets or crumpled into balls. The theory of such
approach is that the metal net promotes heat conduction and avoids
static electricity build up, and thus reduces the risk of
explosion. Although the approach has merit, there is nevertheless a
substantial need for improvement, mainly because of deficiencies in
the physical characteristics of the metal nets and balls, and also
because of inefficiencies in the methods and apparatuses for
producing such materials.
[0006] It is an object of the present invention to provide a
product which is substantially more effective than known products,
not only in the extinguishing of surface fires but also in the
prevention of explosions in fuel tanks and the like.
[0007] It is a further object of the invention to provide a fire
extinguishing product which can be transported to the site of a
surface fire in compact, semi-manufactured form and then stretched
to its fully manufactured form as it is applied to the surface of
the fire over an extended area.
[0008] It is another object of the invention to provide a product
for filling into containers for fuel and other explosive materials
to provide a highly superior anti-explosive protection.
[0009] It is a still further object of the invention to provide
unique methods and apparatus for production of the said new
product.
[0010] Other objects and advantages will become apparent as the
specification proceeds.
SUMMARY OF THE INVENTION
[0011] This invention is based on the development of a new form of
an expandable slit metal foil which may be stretched into a
three-dimensional metal net having unique properties. The expanded
metal net is useful in extinguishing surface fires and also in the
prevention of explosions in fuel containers and the like. It is
also useful for other purposes, which will be explained
hereinafter.
[0012] In one of its forms, the product of the invention is an
expandable metal product comprising a continuous sheet of metal
foil having discontinuous slits in spaced apart lines parallel to
each other but transverse to the longitudinal dimension of said
sheet. When said continuous sheet is stretched longitudinally, it
is transformed into a three-dimensional metal net, and when said
net is laid over a surface fire the fire is smothered and thus
extinguished.
[0013] The fire extinguishing capability of the metal net is based
on the phenomenon that flame at the surface of a burning material
cannot pass upwardly through the pores or eyes of the metal net. In
a normal fire, the heat of the burning causes material at the
surface of the fuel to vaporize and mix with the oxygen in the
atmosphere above it to produce a flammable mixture. If the metal
net of the present invention is interposed between the surface of
the burning material and the atmosphere, the heat conductivity of
the metal net reduces the heat of the fire and thus reduces the
amount of vapor being produced. The net also prevents the flame at
the surface of the burning material from reaching the flammable
mixture of vapor and atmosphere above the fire, and for these two
reasons the conditions for continued burning are removed and the
fire is extinguished.
[0014] The expandable metal product of the present invention
provides a significant advantage in the fighting of fires covering
a large surface area. In producing the expandable product, rolls of
continuous metal foil are passed through banks of slitting knives
to provide lines of discontinuous slits which are parallel to each
other but transverse to the longitudinal dimension of the
continuous sheet. The slitted sheet is then, in the same process,
and without stretching, collected on a roll, ready for
transportation to the site of a fire. In their unstretched form,
the rolls are very compact, and large numbers of them can be
transported by aircraft or other means to the location of a fire.
At the fire, the metal foil is unrolled and stretched as it is
applied to the surface of the fire. The stretching of the
expandable product increases the surface area by approximately a
tenfold factor. For example, if a roll of this material in its
unstretched form is 44 cm wide and 500 m long, it will cover 220
square meters in its unstretched form, but this will be increased
to 2,000 square meters in its stretched form. It will thus be seen
that a substantial advantage is gained in terms of transporting the
raw material in compact lightweight form and then transforming it
by stretching to cover large areas of burning surface at the site
of the fire.
[0015] In a specific embodiment of the invention, the rolls of
slitted foil in the unstretched form can be carried in airplanes or
helicopters over a burning area, and weights can be applied to the
ends of the sheets, such that, as the weights fall toward the
burning area, the foil unrolls and is stretched as it unrolls, thus
covering the greatly expanded area of the stretched metal net.
[0016] It is a feature of the invention that, in the manufacture of
the expandable metal foil, the transverse slit lines are made to
extend to the longitudinal edges of the foil sheets, thus
eliminating unslit longitudinal margins which might resist
longitudinal stretching of the slit sheet when subjected to
longitudinal tension. This feature enables the rolls of expandable
metal foil to be stretched into metal nets as they are unrolled at
the sites of fires, thus providing the very substantial gain in
area of coverage, as described above.
[0017] In another of its forms, the metal net of the present
invention is formed into small ellipsoid shapes which, by
themselves or in combination with large sheets of expanded metal
net, are useful not only for extinguishing surface fires but also
for filling containers of fuel to prevent explosions therein. If
the ellipsoids are to be used on the surface of water or other
liquid, they are provided with floatable cores. In the practice of
one embodiment of the invention, such ellipsoids are placed on the
surface of the liquid fuel in a fuel tank and provide a floating
surface layer on said liquid. The ellipsoid shape enables the units
to nestle together on the surface, eliminating vacant spaces
between them, thus providing a continuous surface cover with no
gaps through which flame from the liquid can upwardly escape. In
another embodiment, the ellipsoids are used to completely fill
large or small containers of fuel, for the purpose of preventing
explosion of the fuel; and in this arrangement also, the ability of
the ellipsoids to nestle together provides a superior gap-free
configuration. In this respect, the ellipsoidal units of the
present invention are superior to metal nets which are crunched
into the shape of spheres, since a layer of floating spheres
inevitably leaves gaps or spaces between the spheres, through which
flame or heat from the liquid fuel can escape upwardly.
[0018] In the practice of another embodiment of the invention, the
above-described ellipsoids with floatable cores are distributed
over a fire burning on the surface of water, and then sheets of the
expanded metal net of the present invention are laid in place on
top of the floatable ellipsoids, thus preventing the sheets of
expanded metal net from sinking below the surface. In the practice
of a further embodiment, the above-described ellipsoids are
distributed in large numbers on the surface of land fires, and the
ability of the ellipsoids to nestle together with each other
provides a continuous layer of metal net for smothering the fires,
similar to the manner in which the sheets of expanded metal net
operate.
[0019] The present invention also relates to apparatus for
producing an expandable metal product comprising a pair of opposing
rotatable cylinders, means for rotating said cylinders at
substantially the same speed, and means for passing a continuous
sheet of metal foil between said cylinders, the first of said
cylinders having spaced apart discontinuous knives attached to its
outer surface in lines transverse to the longitudinal dimension of
said continuous metal sheet, and the second of said cylinders
having corresponding base members cooperating with said knives to
produce lines of discontinuous slits in said continuous sheet of
metal foil. In a variation of said apparatus, the slitting knives
are replaced by spaced punches for the production of perforated
sheets of metal foil.
[0020] A further embodiment of the invention relates to apparatus
for forming sections of expanded metal foil into ellipsoidal shapes
and for inserting floatable balls or other materials on the
interior of said ellipsoids during the manufacture thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The objects, features and advantages of the invention will
be apparent to those skilled in the art from the following detailed
description, taken together with the accompanying drawings, in
which:
[0022] FIG. 1 is a top view of a sheet of expandable metal foil
made in accordance with prior art procedures, showing the pattern
of longitudinal slits, as well as the margins along the edges of
the sheet.
[0023] FIG. 2 is a top view of the expandable metal foil of the
present invention, showing the pattern of transverse slits and the
absence of margins.
[0024] FIGS. 3A through 3E are top views of the expandable metal
product of the present invention, showing the change in
configuration as the slitted sheet is pulled to open up the
expanded metal net product.
[0025] FIG. 4 is a perspective view showing the ellipsoid form made
from the expanded metal net of the present invention.
[0026] FIG. 5 is a perspective view of a hollow floatable ball
which may be inserted on the interior of the ellipsoid form.
[0027] FIG. 6 is a perspective view of the apparatus for producing
the slitted, expandable metal foil product of the present
invention.
[0028] FIG. 7 is a top plan view of the same apparatus.
[0029] FIG. 8 is a side view of the same apparatus.
[0030] FIG. 9 is an elevational view showing the opposing cutting
cylinders, together with some of the discontinuous spaced apart
knives for cutting slits in the sheet of metal foil passed between
said cylinders.
[0031] FIGS. 10A and 10B are perspective views of elongated keys of
the present invention, holding double and single-edged knives which
are attached to the surface of the cutting cylinder.
[0032] FIG. 11 is a perspective view of the first cutting cylinder,
showing multiple spaced apart keyways on the surface of the
cylinder and running the length thereof. Also shown inserted in one
of said keyways is one of the elongated keys carrying a line of
spaced apart slitting knives.
[0033] FIG. 12 is a perspective view of one of the elongated keys
carrying 4 lines of spaced apart discontinuous slitting knives.
[0034] FIG. 13 is a perspective view of another of the elongated
keys carrying 2 lines of spaced apart discontinuous slitting
knives.
[0035] FIG. 14 is an end view of the first cutting cylinder,
showing how the elongated knife keys fit in the keyways on the
surface of the cylinder.
[0036] FIG. 15 is a perspective view of the first cutting cylinder,
showing the circular end plate which is used to lock the keys in
the keyways on the cylinder, as well as a portion of the driving
mechanism for the cylinder.
[0037] FIG. 16 is a perspective view of the second cylinder,
carrying spaced apart keyways which cooperate with the slitting
knife keys on the first cylinder to cut slits in the metal foil
sheet.
[0038] FIG. 17 is a perspective view of the first cutting cylinder,
wherein the elongated keys which are inserted in the keyways carry
rows of cylindrical punches for cutting round holes or perforations
in the metal foil sheet.
[0039] FIG. 18 is a perspective view of two of the cylindrical
punches designed for use in the arrangement shown in FIG. 17.
[0040] FIG. 19 is an end view of the first cutting cylinder,
showing how the elongated keys carrying the punches are fitted into
the keyways in the surface of the cylinder.
[0041] FIG. 20 is a perspective view of the first cutting cylinder
fitted with a modified arrangement for punching holes or
perforations in the metal foil sheet.
[0042] FIG. 21 is a perspective detail view of one of the rings
carrying the cylindrical punches, under the arrangement shown in
FIG. 20.
[0043] FIG. 22 is a perspective detail view of one of the spacer
rings used in the arrangement shown in FIG. 20.
[0044] FIG. 23 is a perspective detail view of the threaded
cylindrical punches used in the arrangement shown in FIG. 20.
[0045] FIG. 24 is a perspective view of another arrangement for a
cylinder carrying threaded punches for cutting perforations in a
metal foil sheet.
[0046] FIG. 25 is a perspective view of the machine for converting
the expandable metal foil product of the present invention into the
form of an ellipsoid.
[0047] FIG. 26 is a top plan view showing multiple work stations
located on the frame of the ellipsoid machine.
[0048] FIG. 27 is a side view showing the male molding pistons and
their casings and the female molding pistons and their casings, in
place at each of the work stations on said ellipsoid forming
machine.
[0049] FIG. 28 is a detail view showing the shape of the male and
female molding pistons and the closing piston.
[0050] FIG. 29 is another side view showing the work stations and
the second frame carrying the cut-off knives and the male molding
pistons, as well as the third frame carrying the female moldings
pistons.
[0051] FIG. 30 is a perspective fragmented view of one of the work
stations, showing the cut-off knives and the guide plate for the
opposing molding pistons.
[0052] FIGS. 31A and 31B are side and top views showing details of
one of the guide plates for the molding pistons.
DETAILED DESCRIPTION OF THE INVENTION
[0053] The Product and Its Uses
[0054] Referring to the drawings, the expandable metal product of
the present invention is exemplified by the continuous sheet of
metal foil 10 shown in FIG. 2. As shown, the sheet of metal foil 10
is a small segment of a much longer sheet which normally is
gathered in rolls containing a single sheet as long as 500 meters,
or more. The width of the sheet 10 may be chosen from any number of
practical dimensions. Widths in the range from 11 to 55 cm are
preferred.
[0055] As noted, sheet 10 is provided with discontinuous slits 11
in spaced apart lines which are parallel to each other but
transverse to the longitudinal dimension of the sheet 10. The slits
11 in each line are separated by unslit segments or gaps 12, and it
will be noted that the slits 11 in each line are offset from the
slits 11 in adjacent lines. Similarly, the gaps 12 in each line are
offset from the gaps 12 in adjacent lines. The apparatus and method
for producing the slitted metal foil 10 of the present invention
are described in detail in the later section of this specification
entitled "The Slitting Machine".
[0056] It is a feature of the invention that the slits 11 extend to
and intercept the longitudinal edges 13 of sheet 10, so that there
are no unslit margins in the product. Although normally the slits
in each line will intercept the edges 13, an arrangement in which
only alternate lines of slits intercept the edges is also within
the purview of the invention.
[0057] For the firefighting uses of the expandable metal product it
is desired that the metal foil be very thin and that the slits in
each line and the spaces between lines of slits be very small.
Thus, the thickness of the foil used to produce the product should
be in the range between 0.028 and 1.0 mm, and the preferred
thickness is between 0.028 and 0.1 mm.
[0058] The length of each slit 11 is in the range between 1 and 2.5
cm, and the unslit sections or gaps 12 between each slit are in the
range between 2 to 6 mm long. It is preferred that in any sheet,
the dimensions of all the slits be uniform, as well as the
dimensions of all the gaps, although practical variations of this
are also within the spirit of the invention. As a specific example,
a sheet having gaps 2 mm long between slits 15 mm long would be a
useful combination. Other examples include sheets with gaps 2 mm
long between slits 17 mm long; gaps 3 mm long between slits 17 mm
long; gaps 3 mm long between slits 20 mm long; gaps 4 mm long
between slits 20 mm long; and so on. The distance 14 separating
lines of slits may be varied, depending on the thickness desired
for the resulting expanded metal net. The distance 14 is ordinarily
in the range between 1 and 4 mm, with either 1 mm or 2 mm being
preferred.
[0059] For many of the uses contemplated for the product of the
present invention, the kind of metal used in the metal foil may be
selected from a wide number of metals or alloys which may be
produced in the form of a thin foil. However, for firefighting
purposes, a significant part of the invention is based on the
discovery that expanded metal nets made from alloys of magnesium
with certain other compatible substances have the unique ability to
extinguish burning fires as well as prevent the burning or
explosion of combustible materials. More specifically, in this
embodiment of the invention, it is especially useful to use an
alloy of magnesium with substances such as aluminum, copper,
zirconium, zinc, strontium, Rn(electron), silicon, titanium, iron,
manganese, chromium, and combinations thereof. Alloys such as the
above have the valuable characteristics of not only being
lightweight, strong, elastic, heat-conductive, etc., but also the
important characteristic of being nonflammable. A particularly
useful combination is the alloy of magnesium with aluminum and
copper. Another preferred combination is the alloy of magnesium
with zirconium and strontium. To a somewhat lesser degree, alloys
in which aluminum is substituted for the magnesium, are useful in
the practice of the invention. The invention is illustrated in a
specific example by an alloy comprising 0.25% Si, 0.3% Fe, 0.01%
Cu, 0.01% Mn, 10% Al, 0.1% Zn, 0.08-0.1% Ti, and the remainder Mg.
Such a product possesses tensile strength of 300 N/mm , proof
stress of 200 n/mm , elongation of 10%, and Brinell hardness of
(5/250-30). The magnesium alloy used in the invention should
contain at least 3.0% by weight of magnesium.
[0060] For certain uses, the product of the present invention may
be combined with other materials. For example, if the expandable
metal foil is coated with an alkaline bichromate, the resulting
expanded metal net acts as a corrosion inhibitor, since the
bichromate acts to remove water from fuels and their containers.
Further, if the metal foil is combined with oleates or similar
compounds, the fire extinguishing capability of the expanded metal
net is enhanced, since the oleate emits a dense vapor which covers
the burning material and assists in the smothering of the
flame.
[0061] When the expandable metal foil product of the present
invention, as shown in FIG. 2, is stretched by subjecting it to
longitudinal tension, it is converted into an expanded metal
prismatic net. In the stretching procedure, the horizontal surfaces
of foil are raised to a vertical position, taking on a
honeycomb-like structure. This conversion is shown in FIGS. 3A
through 3E of the drawings. The expandable metal product 10 is
shown in FIG. 3A prior to stretching. When longitudinal tension is
applied in the direction of the arrow 15, the slits 11 begin to
open, and the product assumes the appearance shown in FIG. 3B. The
application of more tension causes a greater opening of the slits,
and the product expands into the honeycomb-like, prismatic form
shown in FIG. 3C. When even further tension is applied, the
configuration becomes as in FIG. 3D, and finally when the greatest
pulling force is applied, the expanded metal net appears as in FIG.
3E.
[0062] It will be noted that, as the tension increases from stage
to stage, the slitted metal foil increases in area. The slits 11
are converted into eyes 16, and the sizes of the eyes 16 reach
their maximum when stretched to the square configuration shown in
FIG. 3C. Correspondingly, the area of the expanded metal net
reaches its maximum at this point. Further stretching begins to
reduce the size of the eyes, and FIG. 3E illustrates the return to
eyes of the smallest dimensions. Thus, by controlling the extent of
stretching, it is possible to produce an expanded metal prismatic
net structure having the desired shape and size of eyes, and the
desired expansion in area, depending on the use intended. The
conversion illustrated in FIGS. 3A through 3E is also accompanied
by an increase in thickness of the product, since the spaces 14
between slit lines assume a thickness dimension as the eyes
open.
[0063] The increase in area when a slitted metal foil is stretched
into an expanded foil prismatic net can be controlled not only by
the extent to which the metal foil is stretched but also by the
dimensions of the slits 11, the gaps 12 between slits, and the
spaces 14 between lines of slits. For example, if a 250 cm sheet of
foil is provided with transverse slits 2 cm in length with gaps of
2 mm between each slit, and a space of 1 mm between each line of
slits, the foil sheet can be stretched to an average area of 2,272
square centimeters, with the thickness of the net being 2 mm (i.e.,
twice the value of the space 14 between each line of slits). If the
spaces 14 between each line of slits are increased to 2 mm, the
foil sheet can be stretched to an average area of only 1,136 square
centimeters, but with a thickness of 4 mm. Thus, if the objective
is to produce an expanded metal net having the maximum in area (as
is desired in extinguishing surface fires), the preferred procedure
is to keep the distance between lines of slits as small as possible
while at the same time controlling the stretching of the sheet to
produce the maximum size eyes, as in FIG. 3C. If greater thickness
of the net is preferred, and area is not as important, as in the
case of producing formed ellipsoids from the net or in
manufacturing some of the construction or insulation materials to
be described hereinafter, then the distance 14 between lines of
slits may be substantially increased. The formula for calculating
the increase in area as described above is:
Area=Unstretched Area.times.[(a-b)/2c].times.[(a+b)/4]
[0064] Where: a=length of slit 11
[0065] b=length of gap 12
[0066] c=distance 14 between lines of slits
[0067] By controlling the extent of stretching, as well as the
dimensions of the slits 11, the gaps 12 between slits, and the
spaces 14 between lines of slits, it is possible to take advantage
of the strength, hardness and other properties of the alloy foil to
produce expanded nets which may be formed into products having
exceptionally high specific internal surface areas (e.g., in the
range of 250 to 325 ft.sup.2 per ft.sup.3) and above; exceptionally
high porosity (e.g., in the range of 80 to 99%); and a volume
resistivity of <50 ohm-m. These characteristics make the
expanded metal net particularly useful in the production of flame
arresters and anti-explosion units. In order to provide expanded
nets with the high specific internal surface area and high porosity
referred to above, it is important to use an alloy foil containing
at least 3.0% magnesium, and preferably the magnesium content of
the alloy should be above 50%. It is also preferred that the space
between lines of slits be in the higher range of 2-6 mm; that the
length of the slits be within the range of 1-2.5 centimeters; and
that the thickness of the foil be between 0.05 and 1.0 mm.
[0068] It is a feature of the invention that the lines of slits in
the expandable metal foil are cut transverse to the longitudinal
dimension of the long continuous sheet of foil. It is also a
feature that the transverse slit lines extend to the longitudinal
edges of the foil sheet, thus eliminating any unslit longitudinal
margins. In the combination of these two features, the expandable
metal foil of the present invention is different from expandable
foil products which have been favored in the recent past. These
distinctions can be understood by comparing the structures shown in
FIGS. 1 and 2. FIG. 1 illustrates the configuration of slits in
expandable metal foils as produced by prior art methods. It will be
noted that the lines of slits 11A run parallel to the longitudinal
edges 13A of the sheet of metal foil. It will also be noted, as
shown in Schrenk U.S. Pat. No. 4,621,397, that substantial
longitudinal margins 17 are left unslit. This is contrasted with
the arrangement of the present invention, as shown in FIG. 2,
wherein the lines of slits 11 run perpendicular to the longitudinal
edges 13 of the continuous sheet, and the lines of slits 11
intercept the edges 13 so that there are no unslit margins.
[0069] The prior art product shown in FIG. 1 is made by slitting
with banks of disc knives mounted at small intervals on a cylinder,
with e.g., 2 mm between discs. The use of disc knives permits the
slits 11A to be made only parallel to the longitudinal edges 13A of
the continuous sheet. That is, the disc knife cylinder must have a
horizontal axle which is mounted transverse to the longitudinal
dimension of the continuous sheet being fed into the knives, and
thus the knives produce slits which are parallel to the
longitudinal dimension. It has been found that disc knives provide
a less than satisfactory means for producing slits in rolls of
metal foil, since it is difficult to prevent left and right
slippage of the foil as it passes under the knives, especially if
dust or metal pits are present. As a result, the slitting is
imperfect, and expansion into appropriate metal nets is hampered.
For this reason, it has not been possible to process sheets of foil
more than about 15 cm in width.
[0070] A further disadvantage of the prior art procedure is that,
since the slits 11A run parallel to the longitudinal edges 13A, the
only way to stretch the foil into expanded form is to grasp the
foil along the entire lengths of both longitudinal edges 13A and
pull in a direction transverse to the longitudinal dimension of the
sheet of foil. This has required that substantial unslit margins 17
be left along both longitudinal edges of the entire length of the
sheet, so that the jaws of the longitudinal tensioning members have
unslit sections of the sheet to grasp at each edge. The unslit
margins 17 have generally been from 1 to 1.5 cm wide, and since the
slit foil sheets which can be produced with disc knives can be no
wider than about 15 cm, it will be understood that as much as 20%
of the foil remains in unslit form. For all practical purposes,
this is wastage, since the unslit portions cannot be used to expand
the area of the resulting expanded net, and in fact the margins
contribute only to an undesired addition of weight in the resulting
net.
[0071] Further, continuous rolls of slit foil in which the slits
run parallel to the longitudinal dimension of the foil sheet, as in
the prior art illustrated in FIG. 1, cannot be stretched by pulling
longitudinally. Thus, they are not capable of one of the important
functions of the present invention--namely, transforming them into
their expanded form while allowing them to unroll from an aircraft
positioned above a fire. In the present invention, large area
surface fires can be extinguished by a procedure which is enabled
for the first time by the unique structure of the expandable metal
foil product of the present invention. In this procedure, multiple
rolls of the expandable metal foil are transported in an aircraft
to a position above the fire. The expandable metal foil at this
stage is in a semi-manufactured condition, in that the foil has
been provided with slits but then rolled back up before stretching
to the expanded form. In this semi-manufactured stage, the rolls of
foil are very compact and occupy a minimum of space in the
aircraft. As the next step, weights are attached to the free ends
of the slitted foil on the rolls, and the weights are dropped out
of the aircraft toward the surface fire. As the weights move
downward, the effect of gravity unrolls the continuous sheets of
slitted foil from the rolls while at the same time pulling and
stretching the slitted foil to transform it into expanded metal
nets of maximum area. In this manner, metal nets hundreds of meters
long cover the fire immediately, causing the fire to be
extinguished. The unique construction of the expandable metal net
of the present invention, therefore, makes it possible to carry
extremely compact rolls of the material to the scene of the fire
and then, in a single step, apply it to the surface of the fire
over an area ten times greater than the original area of the sheet.
Prior art products, with slits running in the opposite direction,
and with unslit longitudinal margins, were incapable of this.
[0072] In another embodiment of the invention, the expanded metal
net of the invention is cut into small segments which are then
formed into small ellipsoid shapes which in themselves are useful
in extinguishing or preventing fires or explosions, or may be used
in combination with larger sheets of the expanded metal net for
such purposes. The ellipsoids generally have a short diameter in
the range of 20 to 45 mm, and a long diameter in the range of 30 to
60 mm, with the distance between focal points measuring
approximately two-thirds of the long diameter of the ellipsoid. In
the preferred embodiment, the ellipsoids have a specific internal
surface area in the range from about 250 to about 325 ft.sup.2 per
ft.sup.3, with particular usefulness in the range from about 300 to
325 ft.sup.2 per ft.sup.3. The ellipsoids also are characterized as
exhibiting and maintaining a porosity in the range of about 80 to
99%.
[0073] For certain purposes, it is desired to include in the
ellipsoid a floatable core made of hollow balls or other floatable,
non-flammable material. FIG. 4 shows the ellipsoid made from the
expanded metal net of the present invention. In the embodiment
shown, the ellipsoid 18 carries a floatable core 19 on its
interior. FIG. 5 shows one form of a floatable ball useful as the
core 19. The apparatus and method for producing these ellipsoids
are described in detail in the later section of this specification
entitled "The Machine for Producing Metal Net in Ellipsoid
Form".
[0074] The ellipsoids of the present invention have a number of
uses. Thus, in their floatable form, they may be distributed on the
surface of flammable or explosive liquids, such as in fuel tanks,
and in such configuration they provide a substantially improved
anti-explosive or fire extinguishing function. Their ellipsoid
shape causes them to nestle closely together, so that complete
surface coverage is obtained, with no gaps through which flame from
the liquid can upwardly escape.
[0075] In another application, the ellipsoids (without floating
cores) may be used for filling of containers of fuel, for the
purpose of preventing the explosion of such materials. In this
respect, they are superior to prior art spheres which, because of
their spherical shape, could not nestle together and therefore had
gaps between them through which flame could escape. If containers,
large or small, are completely filled with the ellipsoids, a large
amount of fuel can still be added to the container, to occupy the
interstices in the metal nets from which the ellipsoids are made;
and in such an arrangement the container is rendered
explosion-proof for all practical purposes. With such an
arrangement, if a spark occurs anywhere on the interior of the
tank, the ellipsoid material immediately dissipates the heat of
such spark and thus prevents detonation. To explain with more
particularity, it is known that, in order for an explosion to
occur, it is necessary that three elements must be present--namely,
pressure, proper mixture of fuel vapor and oxygen, and ignition. In
many fuel tanks, particularly those which are only partially full,
the mixture of fuel vapor and oxygen, and the potential for
pressure, are normally present, and therefore an accidental spark,
or even the overheating of the walls of the tank, may supply the
ignition which sets off an explosion. However, when the tank is
filled with the metal net ellipsoids of the present invention, the
possibility of ignition is eliminated because the metal net,
because of its high electrical conductivity (volume resistivity of
<50 ohm-m), immediately conducts the heat of the spark away from
the fuel vapor/oxygen mixture.
[0076] The very small size of the ellipsoids of the present
invention, and their special ellipsoid shape, make them uniquely
useful for filling tanks, especially those having small inlet
openings. Comparable anti-explosive results may be achieved if the
tank is filled with the expanded metal net of the present
invention, in sheet form rather than ellipsoid, but usually such
application requires installation of the sheets during construction
of the tank. In either case, it is important that the ratio of the
volume of the metal net (ellipsoid or sheet) to the volume of the
tank be kept within certain ranges. Generally, if too little metal
net is used, the anti-explosive function will not be achieved,
whereas if the metal net is filled in the tank too densely, the
amount of remaining space for the fuel will be unduly limited. It
is a feature of the invention that the tank be completely filled
with the expanded metal net material but at the same time the
volume of the actual metal itself must be in the range of about 0.4
to 1.1% of the volume of the tank. That is, when the tank is filled
with the expanded metal net, the tank still will have a remaining
capacity of 98.9 to 99.6% for fuel.
[0077] Although this "passive inerting" of fuel tanks has been
tested with other materials, such as reticulated plastic foam or
aluminum net balls or batts, the ellipsoids of the present
invention, because of their high specific internal area and
porosity and because of their ellipsoid shape, provide an
exceptionally effective fuel tank filler, which excels in terms of
properties such as flame arresting, electrical conductivity,
hydrolytic and thermal stability, protection against hydraulic
ramming, the reduction of over-pressure, protection against
corrosion and contamination, and resistance to compacting.
[0078] In another application, the ellipsoids with cores are a
useful adjunct for use in combination with large sheets of the
expanded metal net of the present invention in extinguishing fires
on the surface of water. Thus, if the expanded metal net alone is
laid on the surface of such a fire, its tendency would be to sink
below the surface and thus lose its effectiveness. However, if
prior to laying down the net, sufficient numbers of the floatable
ellipsoids are spread at intervals on the surface, and the expanded
net is then spread over the fire, the ellipsoids will assist in
keeping the expanded net afloat in the position where it will be
most effective in fighting the fire.
[0079] Finally, the ellipsoids without floatable cores can be used
to extinguish land surface fires by covering the fire with large
numbers of the ellipsoids. This may be accomplished by dropping
burlap bags containing the ellipsoids into the surface fire and
allowing the bags to burn and thus release the ellipsoids. The
advantage of the ellipsoids in this configuration is that, by
nestling together because of their shape, they tend to stay in one
place rather than rolling downhill or across flat surfaces, as is
the case with spheres.
[0080] The Slitting Machine
[0081] The machine which is used to produce the slits in the
expandable metal foil product of the present invention is shown in
FIGS. 7 through 16. Referring to FIG. 6, a perspective view of the
machine is shown in which the movement of the metal foil sheet is
generally in the direction indicated by the arrow 89. The machine
has a frame 30 supported by legs 30A and 30B (as well as matching
legs, not shown). The frame includes a pair of laterally spaced,
longitudinally extending rails 31 and 32, designed to accept
transverse supporting members 33, placed at appropriate intervals.
These members have associated locking wheels 33A for adjusting and
locking the members at the desired positions along the rails 31 and
32. Mounted at the input end of the machine is an input feed roller
34 for holding a roll of the continuous sheet of metal foil being
supplied to the machine. The feed roller 34 has an axle 35, one end
of which is secured in the rail 31, and the other end of which is
held by a socket 36 adjustably held by an upright member 37. The
adjusting wheel 38 is adapted to raise or lower the socket 36 to
maintain the axle 35 in a generally horizontal position. An
adjusting wheel 39 controls the left or right movement of the feed
roller 34 on the axle 35, to provide proper alignment of the foil
sheet as it is fed into the machine. Rings 40 and 41 are compaction
members which are designed to prevent slippage of the foil on the
feed roller. The pad assembly 42 contains a brake lining (not
shown) to adjust the rotation speed of the axle 35.
[0082] Mounted on the frame 30 approximately midway along the
length of the machine are a pair of opposing rotatable cylinders 43
and 44 which perform the function of slitting the metal foil sheet
as it passes between them. Cylinder 43 carries on its surface
spaced apart discontinuous knives in lines running along the length
of the cylinder and transverse to the longitudinal dimension of the
metal foil sheet passing under it. Cylinder 44 carries on its
surface base members which cooperate with the knives on cylinder 43
to produce lines of discontinuous slits in the continuous metal
foil sheet passing between the cylinders. Cylinders 43 and 44 are
adapted to rotate on axles 45 and 46 respectively, which are
journaled in upright members 47 and 48. Adjusting screws 49 and 50
work to raise or lower the height of cylinder 43, and adjusting
screws 51 and 52 likewise raise or lower the height of cylinder 44,
thus providing a means of adjusting the distance between the two
cooperating cylinders 43 and 44.
[0083] Mounted at the takeoff end of the machine is a takeup roller
53 for rolling up the continuous sheet of metal foil which has just
been slit by the slitting rollers 43 and 44. The takeup roller 53
has an axle 54, one end of which is secured in the rail 31, and the
other end of which is held by a socket 55 adjustably held by an
upright member 56. The adjusting wheel 57 is adapted to raise or
lower the socket 55 to maintain the axle 54 in a generally
horizontal position. An adjusting wheel 58 controls the left or
right movement of the takeup roller 53 on the axle 54, to provide
proper alignment of the foil sheet as it is rolled up on the
roller. Rings 59 and 60 are compaction members which are designed
to prevent slippage of the foil on the feed roller. The pad
assembly 61 contains a brake lining (not shown) to adjust the
rotation speed of the axle 54.
[0084] The takeup roller 53 and the cutting cylinders 43 and 44 are
all driven by a single source of power (not shown) through chains
62 and 63 (see FIGS. 9 and 15 for detail). The rollers 53, 43 and
44 may be driven at the same speed or, if desired, the takeup
roller 53 may be driven at an increased speed by adjustment of the
ring 61, depending on whether or not it is desired to stretch the
slitted foil before gathering it on the takeup roller.
[0085] At appropriate intervals along the length of the machine,
pairs of horizontal stabilizing rollers 64 are mounted on
transverse supporting members 33 to guide and support the sheet of
metal foil as it is fed from the feed roll 34 through the cutting
cylinders 43 and 44 and finally wound up on the takeup roller 53.
Likewise, at appropriate intervals, pairs of vertical stabilizing
rollers 65 are mounted on the transverse supporting members 33 to
prevent unwanted right or left shifting of the sheet of metal foil
as it passes through the machine. The stabilizing rollers 65 have
associated adjusting wheels 65A for locking them in the desired
positions.
[0086] In the operation of the machine, referring to FIG. 6, as
well as to FIGS. 7 and 8, the leading edge of a continuous sheet of
metal foil 66 (see FIGS. 7 and 8) is taken from feed roll 34,
passed between horizontal stabilizing rollers 64 and vertical
stabilizing rollers 65, then between knife rollers 43 and 44, and
then between additional horizontal and vertical stabilizing rollers
64 and 65, and finally gathered on takeup roller 53. After a
section of foil 66 leaves the knife rollers 43 and 44, it has been
provided with transverse lines of discontinuous slits and is ready,
if desired, to be stretched into a honeycomb-like expanded metal
prismatic net. This stretching can be accomplished immediately
after slitting by causing the takeup roller 53 to rotate at a
faster speed than the knife rollers 43 and 44, so that the slitted
foil sheet is stretched as it travels from the knife rollers and is
wound up on the takeoff roller as an expanded prismatic net.
Otherwise, and for most applications involving the present
invention, it is desirable that the takeup roller 53 rotate at
substantially the same speed as the knife rollers 43 and 44, so
that no stretching of the slitted metal foil takes place. In this
manner, the metal foil is gathered into a compact roll in
unexpanded form and thus occupies substantially the same volume as
the roll of metal foil before slitting. This is the compact form of
the product which is useful to transport in aircraft to a location
above a surface fire, where the roll can be dropped toward the
surface and stretched by the force of gravity as it drops to cover
a greatly expanded area.
[0087] An important feature of the invention is the manner in which
the cutting knives are mounted on the surface of the cylinder 43.
The details of such mounting are shown in FIGS. 9 through 16. As
best shown in FIG. 11, the surface of the cylinder 43 is provided
with a series of parallel keyways extending lengthwise of the
cylinder from end to end. The keyways 67 are trapezoidal in
cross-section, with the narrower dimension at the surface of the
cylinder and the larger dimension located inwardly. Slidably
mounted in these keyways are elongated keys 68 carrying one or more
lines of cutting edges or knives 69. The keyways or grooves 67 are
provided over the entire circumference of the cylinder 43, and when
the elongated keys 68 are inserted in all of these keyways, the
cylinder 43 presents a continuous surface of parallel lines of
knives running transverse to the line of travel of the metal foil
sheet 66.
[0088] It will be noted that the knives 69 are discontinuous. That
is, their cutting edges are interrupted at regular intervals by
neutral sections 70, which are necessary to provide the gaps 12 in
the slits 11 in the expandable metal foil product (See FIG. 2). The
neutral sections 70 are offset from the neutral sections in
adjacent lines, so that the slits in the metal foil will be
staggered, in order to produce the expanded metal net. It will also
be noted that each elongated key 68 may carry only a single cutting
edge 69, as illustrated in FIG. 10B, or double cutting edges 69, as
in FIGS. 10A and 13, or as many as four cutting edges 69, as in
FIGS. 12 and 14. Since it is desirable for many purposes in the
practice of the present invention to produce lines of slits which
are very close together (e.g., 1 mm apart), the double or quadruple
cutting edge arrangement shown in FIGS. 12 and 14 has been found to
be extremely effective.
[0089] As best shown in FIG. 15, the elongated keys 68 are locked
in place in the keyways 67 by an end plate 71, which in turn is
secured by locking nut 72 screwed on axle 45. A corresponding end
plate and nut (not shown) perform the same function at the other
end of cylinder 43. The chain 63 and sprocket 63A used to drive the
cylinder 43 are shown in detail in FIGS. 9 and 15.
[0090] Cooperating with the knife cylinder 43 is the opposing base
cylinder 44. The surface of cylinder 44 may be, if desired, a plain
hard plastic to provide a base against which the knives on cylinder
43 can press to produce the desired slits. A plain plastic surface
is particularly useful in the case where the knives on cylinder 43
have a single edge, as shown in FIG. 10B. However, in the case
where the elongated keys 68 on cylinder 43 carry multiple lines of
cutting edges, separated by grooves, it has been found useful to
provide the surface of cylinder with elongated raised base members
73 (see FIG. 16) which register with the said grooves between
cutting edges of the elongated keys 68 on cylinder 43. It will be
seen that, as the cylinders 43 and 44 rotate, the grooves between
cutting edges on cylinder 43 register with the edges of matching
raised base members 73 on cylinder 44, thus providing a slitting
action on the metal foil which is between the two cylinders. If
desired, the elongated raised base members 73 may be in the form of
elongated keys which fit in elongated keyways on the surface of
cylinder 44, similar to the manner in which the elongated keys 68
are inserted in matching keyways 67 on cylinder 43. Thus, when a
particular set of knife keys are installed in the keyways on
cylinder 43, a matching set of base keys may be installed at the
same time in the keyways on cylinder 44.
[0091] In another embodiment of the invention, the slitting machine
may be modified to cause perforation, rather than slitting, of the
continuous metal foil passing between the cutting cylinders. The
resulting metal foil thus contains multiple small perforations,
rather than slits; and, while the perforated foil is not expandable
to produce an expanded metal net in prismatic form, it is useful in
certain circumstances for spreading over a burning fire to
extinguish the same.
[0092] The modification to provide perforations instead of slits is
illustrated in FIGS. 17 through 19 and involves the use of
elongated keys carrying rows of small hollow punches, instead of
rows of slit-cutting edges as in the previous embodiment. In this
embodiment, the cylinder 43 is provided with the same keyways 67,
but the elongated keys inserted in these keyways are provided with
hollow punches, as shown in FIGS. 17 through 19. The keys 74 have
rows of spaced apart hollow cutting punches 75 which may be
permanently installed on the elongated keys, or removably installed
by the use of threads, friction or other means. The punches 75 are
hollow, with a circular cutting edge 76 at one end, a side outlet
hole 77 which is exposed above the key 74 when installed, and a
bottom outlet opening 78. It is a feature of this embodiment that
keys 74 do not completely occupy the keyways 67, so that a space 79
is left between the bottom 80 of the key 74 and the bottom 81 of
the keyway. Thus, the loose pieces of foil which are punched out of
the foil sheet may be removed by passing out through the side
outlet opening 77 or the bottom opening 78. When exiting through
the bottom opening 78, the loose pieces fall into the elongated
space 79 in each keyway and may then be blown out of the cylinder
by any suitable air jet means (not shown). In this embodiment, it
is preferred that the bottom cylinder 44 be provided with a
continuous hard plastic surface, against which the punches 75 may
bear to cut the perforations.
[0093] A still further embodiment for using the said machine for
perforating metal foil is shown in FIGS. 20 through 23. In this
embodiment, multiple rings 82 whose inside diameter matches the
outside diameter of cylinder 43 are installed on the cylinder 43,
as shown in FIG. 20. The rings carry hollow punches 83, which may
be permanently installed in the rings or threadably inserted in the
holes 84 thereof. The rings 82 may be placed on the cylinder 43 in
contact with each other, or they may be spaced apart by use of
spacer rings 85, depending on how densely the foil sheet is to be
perforated. As shown in FIG. 20, the rings 82 may be locked into
place on the cylinder 43 by use of lock nuts 86 which register with
keyways 87 in the surface of cylinder 43. FIG. 24 shows another
modification in which the hollow punches 83 are screwed directly
into holes 88 in the surface of cylinder 43.
[0094] The Machine for Producing Metal Net in Ellipsoid Form
[0095] The machine for producing the ellipsoid form of the metal
net of the present invention is shown in FIGS. 25 through 31B.
Referring to FIG. 25, a perspective view of the machine is shown,
in which the movement of the slitted metal foil sheet is generally
in the direction indicated by the arrow 90. The machine has a frame
91 supported by legs 92 and 93 (as well as matching legs, not
shown). The frame includes a pair of laterally spaced,
longitudinally extending rails 94 and 95, as well as upright
members 96, 97, 98 and 99 positioned generally at the four corners
of the frame. The frame also includes a pair of laterally extending
rails 94A and 95A (95A is hidden from view in FIG. 25) which
support a lateral horizontal extension 125.
[0096] In the embodiment shown in the drawings, the frame 91
carries four work stations A, B, C, and D, each of which includes a
generally rectangular guide plate 100 having a centrally located
hole 101, best shown in FIGS. 29, 30, 31A and 31B.
[0097] Mounted at the proximal, input end of the machine is an
input feed roller 102 for holding a roll of the continuous sheet of
slitted metal foil being supplied to the machine. The feed roller
102 has an axle 103, one end of which is secured in the rail 94,
and the other end of which is held by a socket 104 adjustably held
by an upright member 105. The adjusting wheel 106 is adapted to
raise or lower the socket 104 to maintain the axle 103 in a
generally horizontal position. The pad assembly 107 is used to
adjust the rotation speed of the axle 103.
[0098] At the proximal end of the machine, slightly downstream from
the feed roll 102, a transverse grasping member 108 is mounted with
its ends riding in the tracks provided by rails 94 and 95. The
grasping member is fitted with spaced clips or hooks 109 which are
designed to engage the leading edge of the continuous sheet of
slitted metal foil on feed roll 102. Means are provided for moving
grasping member 108 from its beginning position shown in FIG. 25 to
the distal end of the machine, thereby pulling the metal foil sheet
down the length of said frame 91 into position above the work
stations A, B, C and D. The means for moving the grasping member
108 is synchronized with the speed adjustment means 107 on feed
roll 102 so that the movement of the continuous sheet of foil
leaving the feed roll is slowed to a rate of travel less than that
of the grasping member 108, whereby the difference in rates of
movement cause the section of slitted metal foil between the feed
roll and the grasping means to be stretched into an expanded metal
net.
[0099] Mounted above first frame 91 is a second frame 110, which
has a rectangular shape generally conforming to the shape of frame
91. Frame 110 is adapted to be reciprocated vertically toward and
away from frame 91 by the action of synchronized power cylinders
111, 112 and 113 (and an additional power cylinder, not shown)
mounted on upright members 97, 99, 98 and 96, respectively.
Attached to the longitudinal rails of the frame 110 are five
transverse cutting knife members 114, 115, 116, 117 and 118.
Cutting knife member 114 is located between the feed roll 102 and
station A; knife members 115, 116 and 117 are located between
stations A, B, C and D respectively; and knife member 118 is
located downstream from station D. Mounted on frame 91, between
each of the guide plates 100, and beneath each of said transverse
knife members is a base member 119 against which the knife members
bear to perform the cutting action. Thus, when the frame 110 is
reciprocated toward frame 91, the transverse knife members make
contact with the base members 119 and cut the metal foil sheet
between said members to provide a generally rectangular individual
sheet of expanded metal net positioned above each of work stations
A, B, C and D. Also mounted between rails 94 and 95 of frame 91 are
a pair of transverse rollers 120, through which the continuous
sheet of metal foil is threaded, and which serve to hold the
leading edge of said continuous sheet after the knife 114 has
severed the rectangular section of metal foil covering station
A.
[0100] Vertically mounted on second frame 110 are four casings 121,
122, 123 and 124 holding four male molding pistons 121A, 122A, 123A
and 124A respectively, said pistons being adapted to reciprocate up
and down within said casings, driven by power means, not shown.
(See FIGS. 27 and 28.) Said pistons are aligned generally with the
central holes 101 in the guide plates 100 at each of work stations
A, B, C, and D, so that when frame 110 has been reciprocated
downwardly toward frame 91, the male molding pistons are caused to
enter said holes, thus intercepting the plane of the expanded metal
foil sheet positioned above said guide plate 100, and causing the
foil to be pushed downwardly through said hole 101. As shown in
FIGS. 27 and 28, the leading edges of said male molding pistons
121A, 122A, 123A and 124A have the shape of a semi-ellipsoid.
[0101] Located underneath frame 91 is a third frame 126 which has a
rectangular shape generally conforming to the shape of frame 91.
Frame 126 is adapted to be reciprocated laterally back and forth
from a position underneath the work stations A, B, C and D on frame
91 to a position underneath lateral extension 125, by the action of
power cylinder 127. Extensions such as member 128 ride in the
tracks of rails 94A and 95A to guide frame 126 in its horizontal
reciprocal movement as described above.
[0102] Third frame 126 has four holes 129, 130, 131 and 132 which
register with the holes 101 in guide plates 100 at each of work
stations A, B, C and D when frame 126 is in place under frame 91.
Mounted on the underside of frame 126 are four open top casings
133, 134, 135 and 136, whose open tops register with the four holes
129, 130, 131 and 132 respectively. Said casings hold four female
molding pistons 133A, 134A, 135A and 136A, said pistons being
adapted to reciprocate up and down within said casings, driven by
power means, not shown. The molding surfaces of said female molding
pistons have the shape of a semi-ellipsoid.
[0103] The lateral horizontal extension 125 of frame 91 has four
holes 137, 138, 139 and 140 which register with holes 129, 130, 131
and 132 respectively when third frame is in position underneath
extension 125. Mounted on the topside of extension 125 are four
open bottom casings 141, 142, 143 and 144, whose open bottoms
register with the four holes 137, 138, 139 and 140 respectively.
The casings hold four female closing pistons 141A, 142A, 143A and
144A respectively, said closing pistons being adapted to
reciprocate up and down within said casings, driven by power means
not shown. The molding surfaces of said closing pistons have the
shape of a semi-ellipsoid.
[0104] In the operation of the machine, a roll of slitted metal
foil (unstretched) is placed on feed roll 102, and power cylinder
127 is activated to move third frame 126 in position under first
frame 91. The leading edge of the slitted metal foil sheet on feed
roll 102 is threaded through horizontal rollers 120 and then
engaged by the clips 109 on transverse grasping member 108. The
power means for moving member 108 is activated so that member 108
is moved down the length of frame 91 to the distal end thereof,
thereby unrolling the slitted metal sheet from feed roll 102 and
pulling the same across the four work stations A, B, C and D. Since
the rate of movement of the grasping member 108 is greater than the
rate of movement of the slitted metal sheet leaving feed roll 102,
there is a resulting stretching of the metal foil, such that by the
time the grasping member reaches the distal end of frame 91, the
slitted metal sheet has been transformed into an expanded metal net
in prismatic or honeycomb form.
[0105] At this point, power means 111, 112 and 113 are activated to
move reciprocating second frame 110 downwardly toward frame 91. As
frame 110 makes contact with frame 91, the horizontal knives 114,
115, 116, 117 and 118 mounted on frame 110 bear against
corresponding base members 119 which are mounted on frame 91 to
thus sever the sheet of expanded metal net into four separate,
generally rectangular sheets, one of said sheets being positioned
above each of stations A, B, C and D. The end of the slitted metal
net which is severed by knife 114 becomes the leading edge for
operation of the next cycle of the machine and is held between
rollers 120 awaiting the beginning of said cycle.
[0106] While second frame 110 is still in its down position, as
described above, the power source for male molding pistons 121A,
122A, 123A and 124A is activated, thus driving said pistons
downwardly toward and through the plane of the metal net sheet
positioned above each of stations A, B, C and D. Simultaneously,
the power source for female molding pistons 133A, 134A, 135A and
136A (mounted on the underside of third frame 126) is activated,
thus driving said pistons upwardly to register with their
corresponding male molding pistons. As a result of such molding
action, the separate sheets of metal net at each station are formed
into hollow semi-ellipsoid shapes having an open top, such
semi-ellipsoids being retained in the casings 133, 134, 135 and 136
which are mounted on the bottom side of third frame 126.
[0107] Following this, the power cylinders 111, 112 and 113 are
activated to move second frame 110 upwardly away from first frame
91, and the male molding pistons are also reciprocated upwardly. At
the same time, power cylinder 127 is activated to move third frame
126 laterally into position below lateral extension 125. In this
position, the casings 133, 134, 135 and 135, each holding a hollow,
open-top semi-ellipsoid of metal net, are positioned below the
casings 141, 142, 143 and 144 mounted on the topside of lateral
extension 125. The power means for the female closing pistons 141A,
142A, 143A and 144A is then activated, and said closing pistons
move downwardly to close off the hollow semi-ellipsoid forms into
finished metal net ellipsoids.
[0108] Finally, the closing pistons are reciprocated upwardly, the
metal net ellipsoids are ejected from their casings, and power
cylinder 127 is activated to move third frame 126 back to its
original position under first frame 91, ready for start of the next
cycle.
[0109] In an embodiment of the invention wherein floatable balls or
other materials are inserted on the interior of the metal net
ellipsoids, a floatable ball reservoir 145 is mounted above lateral
extension 125, at a point intermediate between the stations A, B. C
and D and the point where the closing pistons operate. Thus, when
third frame 126 is being moved from its position under first frame
91 toward its final position under the closing pistons on lateral
extension 125, it is possible to cause frame 126 to pause under
floatable ball reservoir 145, so that a ball may be dropped through
bottom holes 146, 147, 148 and 149 into the open tops of the hollow
semi-ellipsoids resting in casings 133, 134, 135 and 136
respectively. The movement of third frame 126 is then continued to
the final position where the hollow semi-ellipsoids containing the
floatable balls are closed into completed ellipsoid form.
[0110] It will be understood that the entire operation as described
above may be performed on a roll of metal foil which has already
been expanded into the prismatic net form. The only difference in
the operation under such circumstances is that the speed of
movement of the grasping member 108 would be synchronized with the
speed of rotation of feed roll 102, such that no further stretching
of the metal net would take place.
[0111] Other Uses for the Product of the Present Invention
[0112] By substituting other materials for the metal foil in
producing an expandable product, it is possible to use the product
in a number of different industries or applications, such as the
packaging, insulation, or construction industries or as decorative
items.
[0113] For example, if cardboard or strong kraft paper is used as
the material, and if the placement of the knives on the slitting
machine is adjusted for wider spaces between lines of slits, an
improved packing or insulation material can be made for use in
place of materials such as corrugated cardboard or air bubble
insulation. The difficulty with present insulation materials is
that they must be manufactured in finished form at the insulation
plant and then transported in their bulky finished form to the
different sites where they will be used. By use of the present
invention, however, slitted cardboard or plastic sheets can be
produced at the manufacturing site and then, prior to stretching
into the net form, they can be transported in their compact,
unstretched form to the place of use, where they can be stretched
into final net or honeycomb form for use in producing boxes,
spacers or other insulating items similar to the corrugated
cardboard presently used. Thus, transportation and storage of large
bulky items can be avoided.
[0114] In the roofing industry, the product of the present
invention can be used as an improved replacement for the layers of
tar-saturated cardboard covered with sand presently used for
protecting and insulating roofs against water and heat or cold. The
current procedure being used in the industry involves laying down a
layer of tar saturated cardboard and then covering with a layer of
sand, then another layer of tar or pitch, and a further layer of
sand, and so on until the desired thickness for insulation has been
accomplished. In the practice of the present invention, a single
effective layer can be produced by adding an intermediate stage to
the operation of the slitting machine. Thus, cardboard is used as
the sheet material being fed to the machine, and the pulling speed
of the takeoff device is adjusted to stretch the slitted sheet as
it issues from between the slitting rollers. At this stage, before
the sheet is removed from the machine, it passes over a work
station where a mixture of melted tar and sand is distributed in
the cells or eyes of the expanded net and a final layer of thin
sand particles is distributed on the surface prior to hardening.
The product is then hardened by a blast of cold air and then
collected in rolls or sheets on the takeoff device. The resulting
product can be used as a single layer for the insulation of roofs,
in place of the labor-consuming multiple layers currently used. In
another embodiment, rolls of slitted cardboard in unstretched,
compact form can be transported to the construction site, where the
material can be stretched into expanded net form, laid in place,
and filled with tar and sand in situ.
[0115] In the construction industry, the metal nets of the present
invention may be used to produce improved construction materials
such as briquettes, tiles, wall board, ceiling tiles, and the like.
For example, if the metal net is made from thin, strong, elastic
material such as the aluminum or magnesium alloys described
hereinbefore, it can be used as a reinforcing web on the interior
of bricks to keep pieces from falling away if for any reason the
brick is broken. Even further, by designing the thickness of the
metal net to varying dimension, the net can be used as the interior
structure for the other construction materials mentioned above. For
example, a tile can be made by first producing an expanded metal
net having the general thickness and shape of the tile to be made,
filling the cells or eyes of the net with the clay, perlite, or
other tile forming material, finishing the surfaces and edges, and
then curing to complete the product. The same procedure can be used
for wall boards and even thicker products such as construction
briquettes made of perlite. Keeping in mind that the thickness and
other dimensions of the expanded metal net can be controlled not
only by adjusting the distance between lines of slits but also the
extent to which the metal is stretched when it is pulled, the
construction materials such as tiles, wallboards, bricks, etc. can
be made in any desired shape or dimension. A special feature of
construction materials produced in this manner is that the presence
of the non-flammable metal net on the interior of the product
prevents the spread of fires by keeping fire from passing through
the net, as described in greater detail hereinbefore. Thus the
construction materials of the present invention are improved not
only from the standpoint of strength and elasticity, but also
provide a previously unavailable feature--namely, fireproofing.
[0116] In the field of decorative arts, the metal nets of the
present invention provide a number of useful innovations. Thus,
when magnesium alloys are used as the raw material, and especially
when combined with alkaline bichromate, the resulting net is an
active, conductive, anticorrosive, rust-repellant, bright, easy to
process, and formable material. For example, because it is bright,
polychrome and stainless, the expanded net can be used as a
flame-retaining decorative screen in front of fireplaces and
stoves, as well as a decoration for windows. As a further example,
if colored foils 0,03-0.08 mm thick are slitted and opened slightly
to make matlike nets, they can be covered with single or double
coats of facing materials and shaped as bracelets to be worn on the
human body as jewelry to reduce static electricity.
[0117] Although preferred embodiments of the invention have been
described herein in detail, it will be understood by those skilled
in the art that variations may be made thereto without departing
from the spirit of the invention.
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