Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF INVENTION:
Field of Invention
The present invention relates to a novel
acoustical construction panel having improved acoustical
properties and a method of making same.
Description of Prior Art i
i
Various types of acoustical panels are known for
use in the construction of walls, floors, and ceilings.
It is also known to construct complicated composite struc-
tures consisting of laminations of different product i
I
layers together with spacer strips to provide air layers
therein in order to improve the acoustical properties of
such structures. It is also known to imbed products
within wall panels to improve the acoustical properties i
thereof.
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A feature of the present invention is to provide
a new acoustical panel construction and wherein the panel
is made from natural wood fibers, paper and starch, and
absent of any chemical toxic products, and wherein the
panel has an average density in the range from about
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15-lb/ft3 to 17-lb/ft3, and further wherein cavities are
perforated on one surface of the panel to increase the I
acoustical surface properties of the panel.
Another feature of the present invention is to
provide an acoustic construction panel made from a compo-
site structure of wood pulp, recycled paper, starch and
wax, and wherein one surface of the panel is provided with
a plurality of cavities perforated therein to increase the
acoustical properties of the panel.
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Another feature of the present invention is
to provide a novel method of producing an acoustic
construction panel using natural wood fibers, paper,
starch and wax, and wherein the panel has a
predetermined density.
According to the above features, from a
broad aspect, the present invention provides an
acoustic construction panel for use with other
building surface elements in constructing composite
walls, flogs, or ceiling structures to improve
acoustical properties thereof. The panel comprises a
composition of natural expanded wood fibers, paper
and starch. The panel has a minimum thickness of
about from %-inch and an average density of about
15-lb/ft3 to 17-lb/ft3, and a plurality of cavities
perforated on one surface of the panel. The
plurality of cavities are spaced apart perforations
of constant cross-section extending entirely
throughout the said one surface. The perforations
extend into the panel to a depth of approximately
one-third the thickness of the panel to provide
improved acoustical damping of said one surface.
BRIEF DESCRIPTION OF DRAWINGS:
A preferred embodiment of the present
invention will now be described with reference to the
examples thereof, as illustrated in the accompanying
drawings, in which:
FIGURE 1 is a fragmented perspective view
of a panel section constructed in accordance with the
present invention;
FIGURE 2 is a block diagram illustrating
the process of making the acoustic panel of the
present invention;
FIGURE 3A is a Table illustrating the
compression force required to obtain a panel with a
predetermined compression characteristic;
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FIGURE 3B is a characteristic curve
illustrating the resistance to compression of the
panel;
FIGURE 4A is a Table similar to Figure 3A
but relating to a panel having a different
composition mixture;
FIGURE 4B is a characteristic curve similar
to Figure 3B but relating to a panel having a
different composite mixture;
FIGURES 5A to 5D are section views as
showing different composite wall, ceiling and
flooring structures illustrating different
utilizations of the acoustic panel of the present
invention; and
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FIGURES 6A to 6C are section views illustrating
floor and ceiling structures utilizing the acoustic
panel of the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS:
Referring now to the drawings, and more
particularly to Figures 1 and 2, there will be
described the construction of the acoustical panel 10
of the present invention. The panel 10 consists
essentially of a composite mixture of wood fibers 11
and paper 12 mixed with a predetermined quantity of
starch and wax. The panel is formed with an
approximate thickness of %-inch and the size and
density of the panel can vary depending on its intended
utility. The panel is also compressed and dried to
have an average density in the range from about 15-
lb/ft3 to 17-lb/ft3 . After the panel has been dried,
cavities 13 are perforated on one of its surfaces,
herein surface 14. As shown at 13' the cavities are of
circular cross-section and extend into the board to a
predetermined depth, herein 1/-inch deep which is one-
third of the total thickness of the panel 10. The
cavities have a diameter of approximately 11/64-inch.
With these characteristics the panel has good
structural characteristics.
The panel may also be formed by using recycled
paper products whereby to reduce the cost of the
product, and to provide a use for such paper. Such a
panel also has a thermal insulating factor of R2 . The
cavities 13 are also disposed in parallel rows and
offset from one another so that the perforations 13 of
adjacent rows are disposed intermediate the
perforations in rows on each side thereof.
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Referring now more particularly to Figure 2
there will be described the method of constructing the
panel 10 of the present invention. Firstly, wood
products, preferably but not exclusively, aspen wood
pieces 15 are fed to a wood pulp refiner 16, as is well
known in the art, to refine or pulverize the wood pieces
into wood pulp. The wood pulp is then transferred into a
holding tank 17 into which hot water is fed from a hot
water reservoir 18. This wood pulp is retained in the
holding tank for a predetermined period of time, herein 15
minutes, so that the wood fibers expand to improve the
sound absorption properties of the fibers. Recycled
paper, starch and wax is then added to the holding tank
and maintained therein to form a composite pulp mixture.
The retention time is approximately 45 minutes. A mixture
or kneader apparatus (not shown) is provided inside the
tank to mix the wood pulp with the paper, starch and wax.
For ease of illustration the paper, starch and wax have
been shown as coming from a single supply 19, but these
may, of course, be supplied independently from one another
in a manner well known in the art. After this total
residual time of 1 hour, the composite mixture is then fed
to a feed tank 20 of a former device 21, which is also
well known in the art, to discharge at its outlet a stream
or layer of this composite pulp 22.
The composite pulp layer is then fed to pressing
rolls or belts 23 and conveyed on a conveyor belt 24 over
suction boxes 25 where a predetermined quantity of water
is removed from the composite pulp. The pressing belts
compress the pulp to a predetermined density. At the
outlet of the pressing apparatus a cutter 26 may be
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positioned to sever the web exiting from the presser
into predetermined panel lengths. These panel
lengths are then fed into a dryer where they are
retained for a predetermined period of time, herein
approximately 1 hour and 50 minutes. The dryer may
consist of a very large chamber having a conveying
apparatus to convey the panels 10 throughout the
dryer so that an elapsed time of 1 hour and
50 minutes results between the inlet and output of
the dryer. At the outlet 27' of the dryer the boards
are fed through a set of perforating rollers 28 where
the cavities 13 are formed on one side of the
panels 10. Finally, the boards are channeled into a
trimmer device 29 to trim the outer edges of the
panel to form panels of precise dimensions. The
panels are then conveyed to a storage area.
For other applications, such as used
between concrete slab 60 and a hard flooring
cover 61, see Figure 5D (i.e., ceramic tiles, marble,
etc.) a high impact panel 62 consisting of about 84%
of wood pulp, 10% recycled paper, 4.5% starch, and
1.5% wax, is utilized. This mixture is compressed to
produce a panel with a density of 17-lb/ft3. Figures
3A and 3B illustrate the compression characteristics
of such a panel, and the press belts 23 are adjusted
in accordance with these characteristics to obtain
the desired product. Such a panel would absorb
impact sound generated by walking on hard surfaces.
This panel is also used in wall, floor and ceiling
structures to absorb airborne sound, such as caused
by radio, television, talking, etc., (see Figures 5A
to 5D) .
When the board is utilized in composite
floor or ceiling structures such board preferably has
a density of 15-lb/ft3 and it is constructed from a
composite mixture of about 87% wood fibers, 8%
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recycled paper, 3.5% starch and 1.5% wax. Figures 4A
and 4B illustrate some of the compression
characteristics of such a composite mixture.
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Referring now to Figures 5A to 5C, there is
shown cross-sections of various wall constructions utiliz-
ing the acoustic construction panel 10 of the present
invention. For example, as shown in Figure 5A, in the
construction of a partition wall the acoustic panel 10 may
be positioned against the studs 30 with the perforated
surface 14 of the panel 10 facing outwardly of the area or
room 31 where sound emanates. The panel is secured to the
studs 30 in the normal fashion by utilizing nails or
screws. Hard wall gypsum panels 33 are then secured over
the acoustic panel 10. On the other side of the stud wall
another hard wall panel 34 is secured. Accordingly, the
sound waves 35 emanated from the area 31 are somewhat
dampened by the hard wall layer 33, and then absorbed by
the acoustic panel 10. The residual noise traveling
through the composite inner wall structure, as shown by
arrows 36, travels through the space 37 between the studs
30 and hits the back wall 34 where it bounces off, as
illustrated by arrows 37, and back into the surface 14 of
the panel. The perforations 13 in the surface increase
the surface area thereof and provide further absorption of
the recoiled sound waves 37. Accordingly, very little
noise penetrates the composite division wall structure, as
illustrated herein.
Figure 5B illustrates a similar structure but
wherein the studs 30' are offset to a minimize the
physical connection between the composite wall formed by
the acoustic panel 10, the hard wall panels 33 and the
backing wall 34. This provides an improved sound damping
structure.
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Figure 5C shows a still further composite wall
structure to improve the acoustical properties of a
wall. As herein shown, the composite wall consists of
a hard wall or gypsum board 40 held by metal studs 41.
The space behind the metal studs 41 is a further metal
stud 42 having gypsum boards 43 and 44 on opposed sides
thereof and in between which an acoustic product 46 is
injected. A further gypsum board 47 may be positioned
over the inner board 44, and the acoustic board 10
secured thereover, but spaced from the metal studs 41
in order not to have a connection with the inner gypsum
board 40 which is vibrated by the noise emanated in the
inner space surrounded by the composite wall structure.
Figure 6A illustrates a ceiling structure wherein
the acoustic panel 10 is secured to the spacer studs
50. Gypsum board 51 is secured to the acoustic panel
10. The area above the ceiling or floor structure 52
may preferably have a carpet 53 secured thereover to
provide further sound damping. Again, the perforated
surface 14 of the acoustic panel 10 is located outside
the area where the sound wave 54 emanates to provide
maximum absorption of that sound wave when passing
through the panel and when rebounding from the upper
surface of the ceiling structure 52.
Figures 6B and 6C show other applications of the
acoustic panel 10, and as shown in Figure 6B, two of
such panels may be positioned on each side of the
spacer studs 50, and again with the perforated surface
facing away from the area where sound emanates. In
this particular application there is provided sound
damping from both areas below and above the ceiling
structure. Figure 6C shows
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another embodiment, similar to Figure 6B but wherein sound
absorption is shielded from the upper side of the compo-
site ceiling structure 52. The gypsum board 55 constitut-
ing the ceiling in the lower area may also be suspended
from the studs 50 by suspension strips 56, as is well
known in the art, in order to improve sound damping.
Many other applications and combination of
structures are possible utilizing the acoustical construc-
tion panel of the present invention. Also, as previously
described, the panel may have different sizes depending on
its intended use. To achieve its intended sound damping
properties and rigidity, it is preferably constructed with
the characteristic as above described. However, the wax
additive is not essential but is provided to give water-
proofing properties to the panels. It is within the ambit
of the present invention to cover any obvious
modifications thereof, provided such modifications fall
within the scope of the appended claims.
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