ACOUSTIC SCREEN FOR SAFE OPERATION OF OPERATOR Russian patent published in 2016 - IPC E04B1/82 E01F8/00 

FIELD: acoustics.

SUBSTANCE: invention relates to industrial acoustics, particularly to broadband soundproofing. Acoustic screen contains a frame with slants of metal sheets and located in it sections of acoustic panels, which are made both as noise reflecting and translucent, and opaque and noise absorbing. Their arrangement in the acoustic screen can be in any combination of vertical and horizontal rows. Each of opaque noise absorbing acoustic panels is made in form of smooth and perforated surfaces, between which multilayer sound absorbing structure is located, which consists of three layers of sound-absorbing material. First layer is more rigid, solid and profiled and is fixed on the smooth surface. Second layer, which is a softer one than the first layer is discontinuous and located in focus of sound reflecting surfaces of the first layer. Third layer of sound-absorbing structure is made from foamed sound absorbing material, for example, construction sealing foam, and is located between first more rigid layer and perforated surface of acoustic panel. Perforated surface has following perforation parameters: hole diameter of 3÷7 mm, perforation percentage of 10÷15 %. As for the shape the holes can be circular, triangular, square, rectangular or diamond-shaped. In case of non-circular holes, it is necessary to consider as the nominal diameter the maximum diameter of the circle inscribed in the polygon. As sound-absorbing material opaque noise absorbing acoustic panels are used plate from mineral wool on basalt base “Rockwool” or “URSA” mineral wool or P-75 basalt wool or glass wool lined with glass felt, porous noise absorbing material, for example foam aluminium or steel, or metal foam, or material in form of compacted crumb hard porous material, for example foam aluminium or steel, or stone-shell limestone with degree of porosity in range of optimal values: 30÷45%, or chips from solid damping material, for example, elastomer, polyurethane or elastrons “Agat”, “Antivibrat”, “Schwim”. Size of fractions of crumbs is within optimal range of values: 0.3…2.5 mm. Discontinuous sound-absorbing layer located in focus of solid profiled layer is made in form of solids of revolution, for example in the form of balls, ellipsoids of revolution, and is attached by means of rods parallel smooth and perforated surfaces, which are rigidly connected with smooth surface by vertical, perpendicular to it, fasteners, for example in form of plates, one end of which is rigidly fixed on smooth surface, and other is made in form of clamp enclosing rod and tightening its screw. Solid shaped layer of sound-absorbing element is made of more rigid sound-absorbing material, in which sound reflection factor higher than that of sound absorption, wherein sections are formed by spherical surfaces, connected to each other so that in each profile creates solid dome profile, focusing reflected sound on same soft discontinuous sound absorbing layer.

EFFECT: invention allows to improve efficiency of noise suppression.

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