ACOUSTIC SCREEN FOR SAFE ACTIVITY OF MAN-OPERATOR Russian patent published in 2018 - IPC E04B1/84 

FIELD: machine engineering.

SUBSTANCE: acoustic screen for safe activity of the man-operator has a framework with slopes made of metal sheets with sections of acoustic panels located therein, which are made both of noise-reflecting translucent and non-transparent noise-absorbing. Their arrangement in the acoustic screen can be in any combination of vertical and horizontal rows. The layers of sound reflecting material are made from heat insulation material capable to maintain the pre-set microclimate in a premise, and as a sound-proof material the plates from basalt-based mineral wool like "Rockwool", or "URSA" mineral wool, or basalt cotton wool P-75, or glass-wool with a woven glass liner are used. The sound absorbing element over the full surface is lined with the acoustic transparent material, for example, glass fabric EZ-100 or polymer "poviden", and the perforated wall has the following perforation parameters: diameter of holes -3÷7 mm, percentage of perforation 10%÷15%. According to the shape the holes can be made as the holes, having round, triangular, square, rectangular or diamond profile. In case of unround holes the nominal diameter shall be maximum diameter of circle inscribed in the polygon. As a sound-absorbing material of non-transparent noise acoustic panels, a porous noise-absorbing material is used, such as aluminium foam or metal ceramics, or metal-porous material, or material in the form of pressed crumbs of solid vibration-damping materials, such as polyurethane elastomer, or compound of "Agat", "Antivibrit", "Shvim" types. The size of the crumb fractions lies in the optimum range of values: 0.3…2.5 mm, or as sound-absorbing material of non-transparent noise-absorbing acoustic panels, a rigid porous material is used, such as aluminium or metal ceramics or a shell stone with a degree of porosity which lies in the optimum range of values: 30÷45%. Each of the non-transparent noise-absorbing acoustic panels is in the form of rigid and perforated walls, between which the layers of sound-reflecting and sound-absorbing materials of different density, which are placed in two layers, are located. The layers of sound-reflecting material are made of a complex profile consisting of uniformly distributed hollow tetrahedrons which allow to reflect sound waves incident in all directions, and arranged respectively at the rigid and perforated walls or each of the non-transparent noise-absorbing acoustic panels comprising a combined sound-absorbing layer of complex shape which is an alternation of solid sections and hollow sections, which frame is made of a rigid sound-absorbing material, the hollow sections are formed by prismatic surfaces having a parallelogram shape in a cross-section parallel to the plane of the drawing, whose inner surfaces have a tooth structure. The vertices of the teeth are directed inside the prismatic surfaces, and the ribs of the prismatic surfaces are respectively fixed on smooth and perforated surfaces. The cavities formed by smooth and perforated surfaces, between which the combined sound-absorbing layer of complex shape is arranged, are filled with soft sound-absorbing material, the cavities of the hollow sections formed by the prismatic surfaces are filled with foamed polymer, for example, polyethylene or polypropylene. Cavities of hollow sections formed by the prismatic surfaces are connected by resonance holes to cavities formed by smooth and perforated surfaces, between which a combined sound-absorbing layer of complex shape is arranged.

EFFECT: increased noise damping efficiency due to introduction of elements of resonance type.

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