US2924857A - Sound absorbing structure - Google Patents

Description

Feb. 16, 1960 GRUBER ETAL 2,924,857

SOUND ABSORBING STRUCTURE Filed Jan. 15, 1957 INVENTORS JOSEPH J. GRUBER y JOSEPH J.DeFALGO ll My? ATT NEYS United States Patent SOUND ABSORBING STRUCTURE Joseph J. Gruber, Depew, and Joseph J. De Falco, Buffalo, N.Y., assignors to Fenestra, Incorporated, Detroit, Mich., a corporation of Michigan Application January 15, 1957, Serial No. 634,273

Claims. (Cl. 204) The present invention relates to sound absorbing structure.

It is an object of the present invention to provide sound absorbing structure comprising a hollow building panel having one perforated wall, a sound absorbing member within said panel having a concave surface at the side thereof adjacent said perforated wall, said surface being transversely concave for substantially the full Width of said member and extending for the full length thereof, said member having a longitudinally extending stifiening rib integrally formed therewith.

It is a further object of the present invention to provide sound absorbing structure comprising a hollow building panel having a perforated front wall and a rear wall provided with a flange extending toward said perforated front wall, a sound absorbing member within said panel having its edge portions formed to extend toward the side thereof adjacent said perforated wall to space the surface of said member from the perforations in said wall, said member having a longitudinally extending stiffening rib provided therein formed by compacting a central zone of said member to provide a flange receiving groove at the rear thereof.

It is a further object of the present invention to provide sound absorbing material for use with a metal ceiling, the material being of a molded construction having two outstanding legs along each lateral edge for spacing the material away from the apertures in the panels, and having a groove along the length of the material intermediate the outstanding legs to reinforce and strengthen the material.

It is a further object of the present invention to provide a sound absorbing material in the form of a molded batt, for use with metal ceiling panels, of a construction that is compact in form and not having any loose materials on the surface to fall through the apertures in the metal panel with the material being compressed along the length of the batt to form a reinforcing groove in the batt.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing illustrating a preferred embodiment of the invention, wherein:

Figure 1 is a perspective view of a batt of the sound absorbing material.

Figure 2 is a perspective view of the batt in place in a metal ceiling panel.

Figure 3 is an end view slightly enlarged of the batt of sound absorbing material.

Figure 4 is a fragmentary perspective view of a modified batt.

In the past sound absorbing walls and ceiiings have been produced by assembling together hollow building panels having the front or exposed wall thereof provided with a mutiplicity of relatively small perforations. Sound absorbing material has been provided within the hollow interior of the panels to absorb the energy of sound en tering the interior of the panels through the perforations.

In accordance with the present invention the sound absorbing'members located within the hollow interior of the building panels are formed of loosely aggregated fibers formed into a predetermined shape and containing suflicient binder material to render the members adequately form-sustaining.

Conveniently, the fibrous material may be glass fibers and the binder material may be a suitable resin such for example as a phenolic resin. In producing the sound absorbing members or pads, they are fabricated from a fleecy resilient superfine mass of glass fibers having distributed throughout a small quantity of the binder. The binder is preferably a thermal setting resin and the pad is formed by a molding process of thermally setting and curing the binder while the fibrous pad is confined to the desired shape.

Referring now to the drawings, a batt of sound absorbing material is generally indicated at 10. The batt is in a molded form of generally rectangular cross-sectional shape. Each lateral edge is rounded as at 12 with the edge terminating in a continuous foot-like portion 14. The surface 16 extends upwardly and inwardly to join the bottom surface 18 spaced from the top surfaces 20 and 22.

Intermediate the portions 14 the surface 20 is rounded as at 24 and extends downwardly and inwardly as at 26 to 2 8 and then parallel to surface 18 as at 30 to 32. Surface 34 extends upwardly and outwardly to where it is rounded at 36 to join surface 22.

The foregoing construction eliminates the necessity of providing separate supporting means within the panel for supporting the fibrous sound absorbing material in the proper position. In the past wire chairs have been required to support the padding material and to retain it in properly spaced condition rearwardly of the perforated panel.

The batt can be fabricated from any suitable sound absorbing material, but glass fibre has excellent sound absorbing properties and when lightly impregnated witha suitable binder such as a phenolic resin, readily molds to the desired form. The diameter of the fibers can vary but fibers having a diameter of .00011 of an inch have been found to give very satisfactory results.

In fabricating the batt the fibers are laid up in parallel layers so that they have a horizontal orientation as indicated by the lines 40 in Figure 3. The uni-directional properties of the fibers give the batt resiliency and strength to resist forces in a direction perpendicular to the horizontal lay-up of the fibers.

The strength of the batt varies with the density of the fibers, the higher the density of the fibers the stronger the batt. To increase the strength of the batt the groove formed by surfaces 26, 30 and 34 is provided. The groove is molded in the batt by compressing the fibers with the density of the fibers increasing from the point 24 to 28 and reaching their maximum density along surface 30. The distance between the surfaces 18 and 30 is approxi' mately one-third that of between 18 and 20 with the fibers being approximately three times as dense between 18 and 30 as those between 18 and 20. The increased density of the fibers along the groove increases the strength of the batt at the groove. The molding process sets the fibers so that the groove retains its form.

It will be understood that the shape and location of the groove and the amount the fibers are compressed can be varied to suit the strength requirements needed in the batt.

In Figure 2 the batt 10 is shown received in an acoustical treated metal ceiling panel 50 which is comprised of a hat-shaped portion 52 which is attached to a flat plate 54 as by spot welding at 56 along the strips 58. A plurality of apertures 60 perforate the plate and allow sound waves to enter chamber 62 of the panel. To increase the strength of the panel 50 the rib 64 is formed in the Patented Feb. 16, 1960 3 portion 52. The batt is inserted through the open end into the chamber 62 with the legs br'fe'et 14 resting on the inner surface of the plate 54.

It will be observed that the foot portion 14 spaces the surface 18 of the 'b'att away from the inner surface of the plate to prevent blocking bf the apertures 60 to allow sound waves to strike the batt and be absorbed and the groove in the batt provides clearance for the rib 64.

In a typical example the finished pad may be produced from one pound density fiber glass pad originally about one and one-half inches thick, molded to approximately one inch thickand having its edge portions tapered to provide legs having an included angle of approximately 30 degrees and provided to extend at'an inclination such that the surface 16 makes an angle of approximately 30 degrees with a plane parallel to the plane of the pad. The legs are located such that the fiat portion of the concave surface of the pad is spaced rearwardly approximately one-half inch from the plane containing the points of contacts of the legs with the perforated plate 54. Since the batt from which the pad is produced has an initial density of approximately one pound per cubic foot, its compression to a thickness of one inch from an initial thickness of one and onehalf inches of course produces an average density of approximately one and one-half pounds per cubic foot. Similarly, the compression of the intermediate zone to form the stiffening rib to a thickness of about one-third that of the pad produces a density in the stiffening rib of approximately four and one-half pounds per cubic foot. The stiffening rib 38 is approximately one inch wide. In compacting fibrous material of this type having a tacky binder distributed throughout, the form-sustaining properties of the completed article-are increased very substantially by a small amount of compression or compacting. It has been found that the compacting of the fibers along the central zone of the pad to a thickness of somewhat less than half the thickness of the balance of the pad produces a strengthening and reinforcing effect much greater than would be expected. The tapered edges are progressively degser toward the edge and at the extreme edge are quite sti In addition to the stiffness imparted by the strongly compressed and bonded together edge portions as well as the intermediate stiffening rib 38 located between the surfaces 18 and 30, it may in some cases be desirable to provide transversely extending stiffening ribs which will interconnect the stiffened edge portions and the longitudinally extending stiffening rib. In Figure 4 such a batt is indicated generally at 70. This batt is provided with the tapered forwardly or downwardly extending edge portions 72 providing the outwardly or downwardly concave front surface indicated generally at 74, as well as the longitudinally extending intermediate compressed stiffening rib 76. In this case however, transversely extending stiffening ribs indicated generally at 78 are provided formed by compressing the material of the fibrous pad in transversely extending elongated areas to a thickness of approximately one-third the thickness of the uncompressed material. These transversely extending thickening ribs provide in effect a grid work of stiffening ribs which renders the whole structure strongly self-support- It will of course be appreciated that if the sound ab- 'sorbing batts are required to be of a relatively greater width than illustrated in the figures, two or more evenly spaced longitudinally extending stiffening ribs may be provided.

The drawings and the foregoing specification constitute a description of the improved sound absorbing structure in such full, clear, concise and exact terms 'as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What we claim as our inventionis:

1. Acoustical structure comprising an elongated hollow panel of rectangular cross-section having one perforated -wall provided with a multiplicity of openings, an elonentire surface of said body adjacent said perforated wall 7 to be spaced therefrom, said body having a stiffening rib extending longitudinally thereof formed of a zone in which said fibers are strongly compressed and bonded together into relatively solid condition, the stiffening rib being formed by fibers compressed from the side of said body opposite said concave side and forming a narrow groove thereat, said panel having a flange extending into its interior from the panel wall opposite said perforated wall and received in said groove.

2. A sound absorbing member for use in a hollow panel having a perforated lower wall, said member being a unitary one-piece elongated body composed in its entirety of loosely aggregated fibers lightly bonded together to render said body form-sustaining, the edge portions of said body being compressed and shaped to extend downwardly from the intermediate portion of said body to form a longitudinally extending downwardly open channel, said compressed edge portions constituting supporting portions eflfective to support the intermediate body portion elevated above the perforated lower wall, a stiffening rib extending longitudinally of said body between its edge portions and in the intermediate elevated portion thereof, the fibers in said rib being compressed and bonded together to substantially higher density than in the remainder of the intermediate portion of said body.

3. A sound absorbing member for use in a hollow panel having a perforated lower wall, said member being a unitary one-piece elongated body composed in its entirety of loosely aggregated fibers lightly bonded together to render said body form-sustaining, the edge portions of said body being compressed and shaped to extend downwardly from the intermediate portion of said body to form a longitudinally extending downwardly open channel, said compressed edge portions constituting supporting portions effective to support the intermediate body portion elevated above the perforated lower wall, said body having a longitudinally extending inwardly depressed surface forming a groove intermediate said edge portions and in the elevated intermediate portion thereof, the fibers inwardly of said depressed surface being compressed and bonded together to substantially higher density than in the remainder of the intermediate portion of said body to form a stiffening rib.

4. A member as defined in claim 3 in which said groove is formed downwardly in the top surface of said body.

5. A member as defined in claim 3 in which the portion of said sound absorbing member outside of said stiffening rib has a density of about one and one-half pounds per cubic foot and in which the compressed material of the stiffening rib has a maximum density of approximately four and'one-half pounds per cubic foot.

References Cited in the file of this patent UNITED STATES PATENTS 1,825,770 Barnett y Oct. 6, 1931 1,874,659 Upson Aug. 30, 1932 1,957,822 Denning May 8, 1934 2,073,036 Voight e Mar. 9, 1937 2,077,889 Mazer Apr. 20,1937 2,187,335 Wagner Jan. 16, 1940 2,357,560 Taforo Sept. 5, 1944 2,450,911 Parket al. Oct. 12, 1948 2,576,698 vRussum Nov. 27, 1951

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