FR2528474A1 - Cutting cellular board into acoustic absorption panels - using lateral slicing to produce two or more panels simultaneously - Google Patents

Abstract

Sound absorbant panels are cut from thick cellular plastics board by lateral cutting to separate the board into at least 2 profiles having complementary undulating or undercut profiles to produce superficial acoustic traps to suppress various frequencies. Superficial acoustic traps to suppress various frequencies. Esp. claimed for shaping panels of expanded, closed-cell, polyethylene from panels weighing e.g. about 200 g/m2. The surface profiles significantly increase acoustic absorbance efficiency compared with plain slabs which rely only on cell dimensions for their absorbance. One cutting pattern illustrated involving use of three saw blades following complementary but different square wave patterns produces 4 absorbant panels from one original slab.

Description

 The present invention relates to a method for manufacturing sound absorption panels as well as the panels obtained according to said method.

 It is known to carry out the treatment of a room by coating the walls thereof with panels generally of synthetic foam of the so-called "fire-proof" type, glued to the walls and / or to the ceiling. The floor can be mounted on an anti-vibration screed also made of cellular material. These panels are generally produced by molding or by extrusion of an expanded plastic material. Among these materials, it is preferred to use closed-cell foams which allow easy maintenance, by washing with a jet, for example.

Unfortunately, these panels are currently of a high cost price, on the one hand and, on the other hand, their quality of absorption of various noises is generally limited to a very narrow portion of the sound spectrum.
The object of the present invention is to remedy these drawbacks.

 According to the present invention, the process for manufacturing dabSorptionacoustic panels is characterized in that it consists in cutting at least two symmetrical panels in the thickness of a foam plate.

 Plastic foam sheets, in polyethylene for example, exist on the market in standardized dimensions and the cutting operation with a saw, a heating wire or by any other means is relatively inexpensive.

 Preferably, the number of panels made from the same plate is four. This is how we obtain, from a 48 mm plate. four panels 33 mm thick. thick, which allows to lower the ctut in a considerable proportion, while gaining on the quality of the insulation obtained by a judicious use of the material.

 According to another characteristic of the invention, the external surface of each of the panels is formed by the juxtaposition of regions absorbing the bass, regions absorbing the midrange and regions absorbing the treble.

 Thus, on a homogeneous support with regard to its constituent material, it is possible to obtain a practically total absorption of the sound spectrum. This absorption previously required the joint use of membranes to absorb the bass and fibrous material to absorb the treble, but it was difficult to combine the two actions, resulting in unsatisfactory compromise solutions.

Other characteristics and advantages of the invention will appear during the description which follows of particular embodiments, given solely by way of nonlimiting examples, with reference to the drawings which represent: - Fig.l a view of plate cutting lines
cellular material according to the invention; - Figs. 2 and 3, perspective views of two panels
insulators according to the invention; - Fig.4, another embodiment for a
neighboring application.

 Fig.l is a side view of a plastic foam plate 1. Inside the plate 1, the lines 2 show the saw cuts according to which the plate will be cut. These saw cuts make it possible to cut, in the same plate four panels, 3,4,5 and 6.

The panels 3 and 6 are identical, as are the panels 4 and 5. They are shown respectively in FIG. 2 and in FIG. 3.

 We see in these figures that each of the panels is constituted by a repetitive structure of flat surfaces and reliefs. As was said above, the flat surfaces are intended to dampen the bass sounds while the reliefs are intended to damp the mediums or sounds at medium frequencies and the trebles or sounds at high frequencies.

 Of course, the panels are separated from each other after sawing, possibly just before their installation, by relative translation.

 In Fig.2, there is shown a panel 3 (identical to panel 6) on which there are flat surfaces 7 separated by raised portions 8, spaced from each other at an appropriate pitch. Each raised part 8 comprises a central part 9 in the form of a mushroom, surrounded by lateral parts 10 whose external faces are inclined relative to the direction normal to the flat surfaces 7. The slots formed between the parts 9 and 10 constitute a kind of "sound trap" for the high frequencies which, after penetration into the cavities thus formed cannot emerge or, only emerge very attenuated since, taking into account the elastic nature of the foam they are reflected very badly. The medium part of the sound frequency spectrum is suitably absorbed by the reliefs 8 themselves.

The flat surfaces 7 constitute resonators which absorb the bass sounds.

 Fig.3 shows a panel of the second type which is, in a way, inverse to the previous one. There are a succession of flat parts 11 and parts in relief, these reliefs being contained in boxes 12. The two symmetrical parts 13 have a general dovetail shape and determine between them a cavity 14 which also plays the role a sound trap for high frequencies. Depending on how the panels 4 are applied to the walls or the ceiling; surfaces 11 or 12 form resonators for the bass.

 Preferably, during the installation of the first and second type panels are juxtaposed. The wall then takes on a strip-shaped structure, which proves to be much more advantageous with regard to sound absorption than large uniform surfaces, whatever the nature of the absorbent material.

 It will be noted that according to the method of the invention, there is no drop of material which makes it possible to improve the cost price.

 Of course, it is possible to use only one type of panel, depending on the problem to be treated.

If one seeks more specifically the absorption of bass sounds, the panels will preferably be glued on the upper surface of the relief 8 in the case of a panel such as that which is represented in Fig. 2 -and on the background 12 in the case shown in Fig. 3.

For a more complete absorption of the sound spectrum, bonding will be carried out on the opposite sides.

 In the case of par.nsux of polyethylene foam, the weight of each panel is approximately 200 grams per square meter. Given the structure of each of these, they are self-supporting and rigid. This characteristic allows them to find a particularly advantageous application in the production of false ceilings which are light, self-supporting, insulating from an acoustic point of view but also from a thermal point of view. This consideration is also valid for other plastic foams and more generally for all cellular materials which can be cut by any means.

 The panels according to the invention can also be glued to prefabricated elements or be included between two steel trays to constitute a roof or partitions.

Finally, although the panels depicted on the
Figs. 2 and 3 are particularly effective with regard to sound absorption, other forms of cutting are possible. It is the same with regard to the number of panels obtained from the same plate by cutting. Of course, this number however depends on the thickness of the original plate.

 Fig.4 shows another panel cutout, also four in number and designated respectively by the references 3,4,5 and6. This is a particular variant of the process intended for a different application from that of the panels described above. In this case, it is a matter of making an anti-vibration support for a floor or the like. While in the previous example iJ was to muffle sounds by absorption, the problem now is to avoid the transmission of sounds through a solid mechanical connection. Another problem specific to this apDlication arises from the fact that the panels have a mechanical force to support, which results in particular from the weight of the floor.

 Fig.4 represents like 1a Fis.1, a plate 1 of cellular material which is cut, in its thickness according to the contours indicated by the lines 2. One also obtains by three saw cuts four panels 3,4,5 and 6 whose section is simpler than the section of the panels of the previous example. The vertical parts 15 form pillars and the floor rests on the horizontal parts 16 of FIG.

 It goes without saying that many variants can be introduced, in particular by substitution of equivalent technical means1 without departing from the scope of the present invention.

Claims (4)

10 Method for manufacturing absorbent panels, in particular  acoustic, characterized in that it consists of cutting  a plate of cellular material, in the thickness  of it, at least two parts of complementary profiles.  shut up. 20 Method according to claim 1, characterized in that  at least four panels are cut simultaneously,  the panels (3,6 and 4,5) being identical two by two,  each panel presenting a succession of flat parts  (7,11,12) and raised parts (8,13) 3 Method according to claim 1, characterized in that  the cutting lines define vertical parts  (15) and horizontal (16). 40 panel obtained by the method according to claim 1,  characterized in that it has flat surfaces  (7,11,12) allowing the absorption of bass sounds  and cavities (14) allowing the absorption of high sounds  intermediate parts absorbing sounds at frequencies  medium. 5D panel according to claim 4, characterized in  that it is made of polyethylene foam with cells  closed. 60 Wall, partition or ceiling including at least one panel  as characterized above.