METHOD TO PRODUCE SOUND-PROOFING PANELS OR SURFACES FOR INTERIORS

Abstract: Method to produce sound-proofing panels or surfaces for interiors, used to line walls or ceilings or as partition elements for interiors such as study rooms, meeting rooms, work rooms, etc., the panels or surfaces including inside lengthwise through holes (11) extending for the entire length of the panel and separated transversely and defining cavities of the desired volume, at least some of the lengthwise through holes (11) communicating with the face of the panel facing towards the room (15) wherein the noise is generated by means of lengthwise slits (12) extending for at least a substantial part of the length of the panel, the sound-proofing panel or surface being obtained by coupling together several finished base elements (110, 310), which include semi-concavities (111, 211) on the respective coupling faces, the semi-concavities (111, 211) of one finished base element (110, 310) being coupled with the semi-concavities (111, 221) of the other finished base element so as to define the lengthwise through holes (11).

Description: "METHOD TO PRODUCE SOUND-PROOFING PANELS OR SURFACES FOR INTERIORS" * * * * * FIELD OF APPLICATION This invention concerns a method to produce sound-proofing panels or surfaces for interiors as set forth in the main claim. The sound-proofing panels or surfaces obtained by means of the invention are applied as a lining to walls or ceilings in rooms or premises where it is necessary to ensure a high level of acoustic insulation and/or sound-proofing, or as dividing or separating elements between rooms. The panels or surfaces obtained by means of the invention are applied particularly, but not exclusively, in meeting rooms, conference rooms, concert halls, gymnasiums, study rooms, noisy work rooms, cinemas, theatres, hotels, television studios, recording rooms, etc. STATE OF THE ART In the field of furnishing and the construction sector, the state of the art covers the use of sound-proofing elements used as an inner lining for walls and/or ceilings to reduce the noise effect in the room or premises where the elements are applied, or at least to regulate the acoustics of the room. Within this field there are various solutions which differ in the material used, the weight and size, the density of the constituent material, etc.; these parameters determine and define the coefficient of acoustic absorption of the element. For example, there are sound-proofing panels made of plaster, full section or with holes, which can be associated inside with filling and insulating material, such as glass wool, and/or lined with covering layers, for example made of plywood or other similar material. There are also sound-proofing panels known to the art which are made of wood, either solid wood or made of adjacent layers of fibres and/or compressed composite material. One particular solution known to the state of the art and particularly appreciated by users provides to make sound- proofing panels including an inner core of composite material with a wood base, such as for example hardboard or MDF, lined at least on the visible face by a layer of covering and/or enhancing material. In this solution, the inner core of panels has a plurality of lengthwise holes of a substantially circular section, advantageously separated at an equal distance, which extend for the entire length or height of the panel. These through holes, which define cavities of the appropriate volume inside the panel, communicate with the face of the panel which faces towards the room where the noise is generated by means of a plurality of slits which extend for a substantial part of the length of the panel. These cavities therefore act as resonators and are able to dissipate any acoustic energy in the region of the respective frequency of resonance; therefore, the noise absorption has a very sharp peak centred on this frequency, and the noise absorption is much less on other frequencies. The frequency of resonance depends on the volume of the cavity and the area of section of the slits which connect the cavity inside the space wherein the noise is generated. The frequency of the slits, or number per unit of width of the panel, which may coincide with the frequency of the inner through holes or be an submultiple thereof, determines the level of sound-proofing of the panel. The higher the frequency of the slits, the greater the sound-proofing level of the panel. The sound-proofing capacity of this type of panel derives intrinsically from its structural configuration. In fact, the sound waves generated in the room are conveyed by these lengthwise slits towards the inner holes and remain trapped there, thus preventing the noise from propagating towards the outside and generating a sound- proofing effect through the successive reverberations of the sound waves inside the holes . In the state of the art, these panels are produced by means of an extrusion method which forms the finished panel with the inner lengthwise through holes already made therein. The lengthwise slits are made during a subsequent step, with a variable frequency so as to achieve panels which are sub-divided into categories, each of which is characterised by a standardised value of sound-proofing. This method of obtaining the sound-proofing panels - by means of extrusion - is extremely complex, and the final cost of the product is very high. Moreover, according to the type of application and/or specific requirements, the final panel thus obtained has to be associated, in a subsequent step, to coverings and/or linings in such a way as to make it fire-proof and/or water- proof, which involves a further increase both in production times and also in the final cost. The extrusion method itself causes an arrangement of the fibres of the core in a vertical direction which is not suitable to intercept the propagation of the sound waves efficiently . Another disadvantage which limits the sound-proofing capacity of the panel thus formed is that the density of the inner core of the panel is substantially uni form for the whole transverse extension of the panel and therefore there are no variations in density to accentuate the sound- proofing capacity of the panel. Another disadvantage caused by the extrusion method is that the panel thus obtained is not very versatile or adaptable to specific and particular requirements which may arise according to the different fields of use. In fact, every variation in size and/or structure of the panel involves a reconfiguration of the extrusion assembly, which requires a long time to re-adapt and causes additional costs. A further disadvantage is that it is impossible for these panels to achieve an efficient sound-proofing for the whole range of frequencies to be abated because of the substantially standardised form of the lengthwise holes and the fixed length of the slits which connect them to the room wherein the noise is generated. GB-A-2JD27.255 describes a sound-proofing panel equipped with cavities of different volume, each of which is pre- determined to absorb prevalently a specific sound frequency. This solution is very complex in construction, since it requires a complex molding procedure and the introduction into the mold of insertions, of variable size, suitable to form the cavities of different volume. Moreover, this solution is not very efficient as far as noise absorption is concerned either, inasmuch as it causes the formation of areas of different levels of absorption which are distributed in a non-uniform manner over the space wherein the noise is generated. The production costs of the panels according to GB'255 are therefore extremely high. WO 85/06240 describes a sound-proofing panel consisting of two wall elements, an inner and an outer element, between which there is a means able to allow the sound waves to propagate, such as air, for example. Inside this means there are acoustic resonators, substantially spherical in shape, each of which is tuned to a specific and characteristic frequency. The resonators can be an integral part of one of the wall elements, or they can be suspended between the wall elements and buried in insulating material. The resonators are connected to relative throats which can be glued or welded in situ. This sound-proofing panel is very complex and expensive to make, and therefore it is applied only in very specific cases where a particular standard of performance is required; it cannot be used to cover extensive surfaces such as walls and ceilings of rooms. Moreover, this panel requires extremely complex assembly operations which lead to even greater costs. Furthermore, the panel requires expensive finishing operations in order to be applied in the room to which it is intended. The present applicant has designed, tested and embodied this invention in order to overcome the shortcomings of the state of the art which have prevented a wider use of these panels because of their high final cost and their lack of versatility and adaptability to specific requirements of the users, and also to achieve further advantages. DISCLOSURE OF THE INVENTION The invention is set forth and characterised in the main claim, while the dependent claims describe variants of the idea of the main embodiment. The purpose of the invention is to obtain a method to produce sound-proofing panels, surfaces or elements for interiors in general which will make it possible to obtain a higher level of sound-proofing at a much more limited cost than that obtainable with methods known to the state of the art. A further purpose of the invention is to obtain a method which will considerably reduce production times and obtain finished elements with the desired and variable characteristics, both in terms of sound-proofing and in terms of size, fire-proofing, water-proofing, insulation, and with every other type of personalisation which will meet the users' specific requirements. The invention provides that, in the finished state and when installed in the room for which it is applied, the sound-proofing panel or surface has the structure described above, that is to say, with inner lengthwise through holes along the whole length, or height, and with lengthwise slits of the desired frequency opening onto the front surface and connecting the holes with the room wherein the noise is generated. According to the invention, the inner lengthwise holes are obtained by matching two semi-holes or semi-concavities. In a first embodiment of the invention, the panel is obtained by coupling two panels together at the front, each one of which having a plurality of open concavities on the front of its face which are substantially semi-circular and separated transversely. The faces of the panels thus worked are then joined together by their front parts, making the semi-circular concavities coincide, so as to obtain a panel with lengthwise circular through holes which extend along the whole length of the panel. According to another embodiment of the invention, the sound-proofing panel or surface is obtained by lateral coupling of substantially vertical sections or strips which have the semi-circular concavities on their opposite side faces. By joining a plurality of such sections or strips at the sides, making the respective side faces coincide in correspondence with the semi-circular concavities, we obtain a sound-proofing panel or surface of the desired size, using substantially the same method of formation as for a matchboard. The sound-proofing panel according to the invention is thus achieved during the assembly step in situ, which considerably facilitates the installation operations for the workers, and thus reduces the overall costs. By using this method no specific working is necessary to form the slits since they can be obtained directly by the conformation of the base sections or strips when joined together laterally. The possibility of using reciprocal male-female joints simplifies and accelerates the coupling operations of the individual base elements, and also causes the automatic coupling of the semi-circular concavities. Moreover, the method makes it possible to obtain either a finished panel or a series of elements which are assembled on site to make the finished element . The semi-circular concavities, whether they are made on the half panels coupled frontally or the vertical sections/strips coupled laterally, are obtained by means of a mechanical process to remove material, for example, by milling. According to a variant, the concavities are obtained by moulding, either hot or cold. According to another variant, the concavities are obtained by means of rolling. According to a further variant, in particular cases and with particular materials, the concavities are obtained b y bending . In one embodiment of the invention, the half panels, or the sections or strips, are glued together. According to a variant, the coupling is achieved by arranging the elements which are to be coupled in an adjacent position during the assembly step, and associated by clamping means, for example, by a vice. According to a further variant, the elements to be coupled are constrained together by means such as screws, nails or similar. The method described above to obtain the sound-proof ing panels or surfaces has many advantages over methods known to the art. In the first place, the use of simple processes, whether they be mechanical or moulding or any other type which are easy and quick to perform, on elements which are already finished in themselves and therefore readily available on the market or which in any case can be achieved inexpensively brings down the costs of pro d uction considerably. Moreover, the invention makes it possible to adapt the sound-proofing panel to the specific and contingent requirements of the user, whether they be functional or aesthetic. It should be noted that the coupling and possible gluing of two half panels, or of the sections/strips, is performed on surfaces which are in themselves smooth and therefore no operational problem is posed. Moreover, the resulting single face of the panel which is visible can be enhanced, lacquered or covered in some other manner in such a way as to meet any specific requirement of the users. If the vertical strips which form the panel are enhanced and covered when they are still in their unassembled state, but after the cavities and slits have been formed, in this case the covering obtained is of a high quality finishing, inasmuch as the visible edges of the slits are also covered, which is not possible with panels made in a single piece at the end of an extrusion or molding process . The base elements in themselves may also have fire-proof, water-proof, insulating or other characteristics, and therefore the panel requires no other subsequent processing or finishing, but is already in its finished state when it leaves the structural processing. The sound-proofing characteristics can be set and personalised according to specific requirements, and also according to the frequency of the lengthwise slits as happens in the state of the art, also by acting on the size and/or conformation of the through holes which need not even be circular, or by varying the material and/or the density of the base elements . One peculiarity of the embodiment wherein the vertical strips or sections are laterally coupled is that it is possible to modify at will the size and/or shape of at least one of the two concavities which form the lengthwise hole in order to obtain a desired and specific sound-proofing effect. Since it is possible to obtain a continuous variation, possibly of a harmonic type, of the shape and size of the semi-circular concavity on the length of the individual section or strip, an efficient sound-proofing effect is obtained for a wide range of frequencies which can cover, for example, the entire spectrum of the voice in a uniform manner. Another advantage of the invention is that the fibres of the inner core are arranged horizontally to the panel; this causes a further sound-proofing effect of the noise generated in the room. A further advantage is that the base elements, obtained by means of moulding, have a greater fibre density near the outer surfaces and a lesser density inside. For this reason, the sound-proofing panel or surface in their finished state has a greater density on the transverse section in the proximity of the outer surfaces and the coupling zone, and a lesser density in correspondence with the bottom of the inner through holes. This alternation of density further accentuates the overall sound-proofing effect of the final panel obtained. According to a variant, the outer face of the panel is associated with a covering layer made of insulating material, possibly maintaining an air gap between the covering layer and the said outer face. According to another variant, in order to further accentuate the insulating effect, particularly for the lower frequencies, lengthwise slits of a variable frequency are made on the outer face of the panel, in correspondence with the lengthwise through holes. ILLUSTRATION OF THE DRAWINGS The attached Figures are given as a non-restrictive example, and show some preferred embodiments of the invention as follows: Figs, la-lc show a side view of the sequence of production of the ' sound-proofing panels according to a first embodiment of the invention; Fig. 2 shows a variant of Fig. lc; Fig. 3 shows another variant of Fig. lc; Fig. 4 shows a section of a finished sound-proofing panel made according to the method as in Figs, la-lc; Fig. 5 shows an application of the panels made according to the embodiment as in Figs, la-lc to a segment of wall in a room; Fig. 6 shows, with a variant on Fig. 5, a segment of wall made with the second embodiment according to the invention; Fig. 7 shows, with a variant on Fig. lc, the embodiment as per Fig. 6; Fig. 8 shows the base element of the wall shown in Fig. 6; Fig. 9 shows a variant of Fig. 8; Fig. 10 shows a variant of Fig. 9; Fig. 11 shows a panel made with a plurality of base elements as in Fig. 9. DESCRIPTION OF THE DRAWINGS The finished sound-proofing panel 10 shown in Fig. lc is made, in the first embodiment, from two half panels 110, themselves finished and identical, one of which is shown in Fig. la. On the outer face 110a of each of the half panels 110, a plurality of lengthwise through concavities 111 are made, for example by means of the mechanical removal of material; the concavities 111 are transversely separated and, in this case, semi-circular in shape. According to variants which are not shown here, in order to obtain a different sound-proofing capacity of the finished panel 10, the concavities 11 may be semi-oval, semi-rhomboid or any other desired shape. The two panels 110 are then coupled, making the respective concavities 111 coincide, so as to obtain a half-worked panel 210 (Fig. lb) which has through holes 11, in this case circular in section, which extend along the whole length of the half-worked panel 210. The next step provides for lengthwise slits 12 to be made on the face 10a of the panel 10 facing towards the room 15 (Fig. 5) wherein the noise is generated; the slits 12 are made in correspondence with the holes 11. In the case shown in Fig. lc, the frequency of the slits 12 coincides with the frequency of the holes 11, that is to say there is a slit 12 for every hole 11. Moreover, in this case the slits 12 are located offset with respect to the centre of the circular hole 11, which further accentuates the sound-proofing capacity of the panel 10. Fig. 2 shows a variant wherein the frequency of the slits 12 is half the frequency of the holes 11. According to other variants which are not shown here, the frequency of the slits 12 can be equal to a desired submultiple of the frequency of the holes 11 so as to obtain a different sound-proofing effect which can be standardised. According to the variant shown in Fig. 3, the outer face 10b of the panel 10 is associated with a panel 13 made of insulating material, there also being included an air gap 14 between the outer face 10b and the insulating layer 13. In this case, to accentuate the insulating effect, slits 112 are also made on the outer face 10b of the panel 10 which connect the outer face 10b with the lengthwise through holes 11. The frequency of the slits 112, in this case, is less than that of the slits 12. In the embodiment shown in Figs. 6-11 the panel 10 is obtained by coupling a plurality of sections or strips 310 at the sides, each of which has semi-circular concavities 211 on the side faces. The semi-circular concavities 211 have a different shape so that, at the moment of lateral coupling, the lengthwise hole 11 is obtained with a substantially circular shape (Fig. 7) . Each section or strip 310 has its side faces appropriately shaped so as to achieve a male-female connection with the side faces of the contiguous sections/strips 310, and also so as to define the slit 12 directly, should it be required, without needing any further processing. To this end, an upper extension 310a cooperates with a limited upper segment 310b of a contiguous section/strip 310, while the lengthened lower extension 310c cooperates with a flattened lower segment 310d of a contiguous section/strip 310 so as to achieve the slit 12. According to the variant shown in Figs. 10 and 11, the sections/strips 310 include, in opposite positions, respective attachment elements, male 16 and female 17, which during the assembly step are coupled respectively with the mating attachment elements, female 17 and male 16, of the adjacent sections/strips 310 (Fig. 11) . This solution facilitates and accelerates assembly operations, and also achieves the automatic coupling of the respective concavities 211 so as to define the substantially circular holes 11. The mating conformation of the sections/strips 310 makes it possible to achieve sound-proofing panels or surfaces of a desired extension quickly and with easy assembly operations, starting from elements which are already finished in themselves, and which can even be assembled on site so as to form the necessary wall. This kind of coupling also makes it possible to easily obtain concavities 211 of a variable size and shape so as to obtain efficient sound-proofing effects for a wide spectrum of frequencies. The embodiment shown in Fig. 9 achieves concavities 211a of a variable size and shape on the length of the relative section/strip 310, achieving in this case a sinusoidal development in such a way as to obtain a high sound-proofing effect for a wide range of frequencies, for example for the whole spectrum of the human voice. In order to further extend the variability of the sound- proofing effect, it is possible to insert mating filling elements of variable size inside the concavities 211. The finished panel 10, since it is formed by the coupling of half panels 110 or sections/strips 310 which in themselves are already finished, intrinsically includes the desired characteristics, for example, fire-proofing, water- proofing, insulation or other, which the base elements already have. Therefore, it does not need any further linings and/or processing and/or finishing and leaves the structural processes already finished. It is also possible to choose at will the material which constitutes the half panels 110 or the sections/strips 310 which are the base elements; apart from composite, wood- based material, also plastic, light metal, expanded or synthetic material, etc., can be used. A further characteristic of the finished panel 10 (Fig. 4) , if wood-based composite material is used, is that the fibres are arranged horizontally to the extension of the panel; moreover, the fibres have a density which is greater in proximity to the inner 10a and outer 10b faces and the coupling zone 10c, and lesser in the intermediate zones. This characteristic derives intrinsically from the fact that the method used to obtain the basic half panels 110 or the sections/strips 310 - that is to say, moulding - gives a greater density of the fibres in proximity with the outer faces and a lesser density in the central area. The alternation of the density of the fibres causes a further accentuation of the sound-proofing effect of the finished panel 10.

Claims: -1b- CLAIMS 1 - Method to produce sound-proofing panels or surfaces for interiors, used to line walls or ceilings or as partition elements for interiors such as study rooms, meeting rooms, work rooms, etc., the panels or surfaces including inside lengthwise through holes (11) extending for the entire length of the panel and separated transversely and defining cavities of the desired volume, at least some of the lengthwise through holes (11) communicating with the face of the panel facing towards the room (15) wherein the noise is generated by means of lengthwise slits (12) extending for at least a substantial part of the length of the panel, the method being characterised in that the sound-proofing panel or surface is obtained by coupling together several finished base elements (110,310), which include semi-concavities (111,211) on the respective coupling faces, the semi- concavities (111,211) of one finished base element (110,310) being coupled with the semi-concavities (111,221) of the other finished base element so as to define the lengthwise through holes (11). 2 - Method as in Claim 1, in which the panels or surfaces (10) are obtained by means of the frontal coupling of two base half panels (110) already finished in themselves, there being made on one face (110a) of each of these half panels (110) a plurality of concavities (111) , substantially se i- circular in section, separated transversely, opening towards the outside and extending over the entire length of the relative half panel (110), the respective worked faces (110a) of the half panels (110) being associated by making the respective concavities (111) coincide so as to define the lengthwise through holes (11) , then, in a subsequent step, the lengthwise slits (12) being made by means of the removal of material, the lengthwise slits (12) connecting the lengthwise through holes (11) with the face (10a) of the panel (10) facing towards the room (15) wherein the noise is generated. 3 - Method as in Claim 1, in which the panels or surfaces (10) are obtained by means of the lateral coupling of a plurality of base sections/strips (310) which are already finished in themselves, on the two side faces of each of the profiles/strips (310) there being a respective concavity (211) , substantially semi-circular in section, open towards the outside and extending over the entire length of the relative section/strip (310), the side faces of the sections/strips (310) being associated by making the respective concavities (211) coincide so as to define the lengthwise through holes (11), the sections/strips (310) including at the sides at least an extension (310c) defining, together with a mating segment (310d) of the adjacent section/strip (310), the relative lengthwise slit (12) to connect the lengthwise through holes (11) with the face (10a) of the panel (10) facing towards the room (15) wherein the noise is generated. 4 - Method as in Claim 3, in which on each section/strip (310) respective segments (310a, 310b) are made for coupling with the adjacent section/strip (310) . 5 - Method as in Claim 3 or 4 , in which on the lateral coupling faces of each section/strip (310) mating male- female (16, 17) elements are made to reciprocally join together the section/strips (310) with a groove-and-tongue j oint . 6 - Method as in any c laim hereinbefore , in which the concavit ies ( 211 ) are made at the side of the relative section/ strip ( 310 ) with a variable shape and size so as to achieve a sound-proof ing ef fect which covers a wide spectrum of frequencies . 7 - Method as in Claim 6, in which the concavities (211) have a sinusoidal development along the longitudinal extension of the lateral face of the section/strip (310) . 8 - Method as in any claim hereinbefore, in which the concavities (111,211) on the half panels (110) or on the sections/strips (310) are obtained by the mechanical removal of material, for example by milling. 9 - Method as in any claim from 1 to 7 inclusive, in which the concavities (111,211) on the half panels (110) or on the sections/strips (310) are obtained by moulding. 10 - Method as in any claim from 1 to 7 inclusive, in which the concavities (111,211) on the half panels (110) or on the sections/strips (310) are obtained by rolling. 11 - Method as in any claim hereinbefore, which includes the use of half panels (110) or sections/strips (310) which themselves have fire-proof and/or water-proof and/or insulating characteristics. 12 - Method as in any claim hereinbefore, which includes the use of half panels (110) or sections/strips (310) made of wood-based composite material, such as hardboard or MDF, lined and/or enhanced at least on the face facing towards the room (15) . 13 - Method as in any claim from 1 to 11 inclusive, which includes the use of half panels (110) or sections/strips (310) made of plastic material or light metal. 14 - Method as in any claim from 1 to 11 inclusive, which includes the use of half panels (110) or sections/strips (310) made of expanded or synthetic material. 15 - Method as in any claim hereinbefore, which provides to associate the outer face (10b) of the finished panel (10) to at least an insulating panel (13), there being an air gap between the face (10b) and the insulating panel (13) . 16 - Method as in any claim hereinbefore, which provides to achieve connection slits (112) between the outer face (10b) of the finished panel (10) and the lengthwise through holes (11).

Inventors: AVIAN OSCAR, AVIAN, OSCAR
Applicants: AVIAN OSCAR, AVIAN, OSCAR
Application year: 1998
Main classification: G10K11
IPC codes: E04B1, G10K11