KOCHETOV SOUND ABSORBER FOR LINING MANUFACTURING FACILITIES Russian patent published in 2016 - IPC E04B1/84 

FIELD: acoustics.

SUBSTANCE: invention relates to industrial acoustics. Sound absorber for lining manufacturing facilities is made in the form of a rigid and a perforated walls, between which there is a multilayer sound-absorbing element. Multilayer sound-absorbing element is made in the form of five layers, two of which, adjacent to the walls, are sound-absorbing layers from materials of different density, while three central layers are combined, herewith the axial layer is sound-absorbing, and two symmetrically arranged, adjacent to it, layers are made from a sound-reflecting material of complex profile composed of evenly distributed hollow tetrahedrons, which enable to reflect sound waves from all directions. Each of the perforated walls has the following perforation parameters: aperture diameter 3÷7 mm, perforation percentage 10÷15 %. Apertures can be made as holes of circular, triangular, square, rectangular or rhomboid shape, herewith in case of unround holes the nominal diameter should be considered the maximum diameter of a circle inscribed in a polygon. As the sound-absorbing material plates are used from Rockwool basalt-based mineral wool, or from "URSA" mineral wool, or P-75 basalt wool, or glass wool with glass felt. Sound absorbing element over its entire surface is lined with an acoustically transparent material, for example, EZ-100 glass fabric or "poviden" type polymer. Herewith the sound-absorbing material used is a porous noise-absorbing material, for example foamed aluminium, or ceramic metal, or stone-shell limestone with the porosity degree within the range of optimal values: 30÷45 %, or metal-PU foam, or a material in the form of compacted crumbs from solid damping materials, for example, elastomer, polyurethane, or "Agat", "Antivibrit", "Schwim" elastrons. Size of fractions of crumbs is within the optimal range of values: 0.3…2.5 mm, and can also be used porous mineral piece materials, for example, pumice, vermiculite, kaolin, slags with cement or other binding, or synthetic fibres. Surface of fibrous sound absorbers is treated with special porous air-permeable paints, for example, of Acutex T type, or coated with air-permeable fabrics or nonwoven materials, for example frost cloth.

EFFECT: technical result is improved efficiency of noise suppression due to expansion of frequency range of resonant modes of operation, which is provided by Helmholtz resonators built in the multilayer sound-absorbing element.

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