| 摘要 |
FIELD: acoustics.SUBSTANCE: invention relates to industrial acoustics, particularly, to broadband acoustic suppression. Sound-absorbing construction of industrial buildings include acoustic enclosures and custom-made sound absorbers. Acoustic enclosures comprise smooth and perforated walls, between which a sound-absorbing material arranged in two layers, one of which is harder, continuous and profiled, and other is soft, discontinuous in form of discontinuous sound absorbers and placed in focus of sound reflecting surfaces of first layer. Solid shaped layer of sound-absorbing material is made from material with sound reflection factor higher than that of sound absorption. Discontinuous sound absorber located in focus of solid profiled layer is made in form of solids of revolution, for example sphere, ellipsoid, cone, truncated cone, and is fixed on perforated wall by means of pins, one end of which is rigidly fixed on perforated wall, and other is pointed and is located in body of discontinuous sound absorbers. Similar single sound dampers comprise a housing made in form of lateral closed surfaces with bottom and flap cover made of perforated sheet of stainless steel or a galvanised steel sheet with thickness of 0.7 mm with a polymer protective-decorative coating such as “Pural” with thickness of 50 mcm or “Polyester” with thickness of 25 mcm, or aluminum sheet with thickness of 1.0 mm and thickness of coating of 25 mcm. Coaxial with housing, and at an equal distance from inner surfaces hollow chamber made of a perforated sheet with surfaces congruent to surfaces of housing is placed. Between walls of housing and chamber is placed a sound absorber formed as a porous noise absorbing material, such as aluminium foam or sintered metal, or metal-foam plastic, or in form of a compressed aggregate of solid vibration-damping material such as an elastomer, polyurethane, or plastic such as “Agat”, “Antivibrit”, “Shvim”. Size of crumbs fractions is within optimal range of 0.3…2.5 mm. Other single-piece absorbers are made of a metal, pressed frame, which is attached to object, and to it is attached a body made in form of an inverted cone, in apex of which there is a hole to accommodate elastic fastening element, such as a spring with a rod on end, which is fixed on top cone of fastening element. At base of cone there is a gasket made of a vibration-damping material, through which fasteners attached to frame and by means of cone base is rigidly fixed to frame by elastic fastening element. On inner surface of cone is attached absorbing non-combustible material, for example PVC foam, fibreglass, wrapped with acoustically transparent material, for example fibreglass. AIR cavity is provided inside said cone between layer of sound absorbing material. Sound absorbing structure is also equipped with spherical acoustic absorber containing active and reactive acoustic absorbers located on a rigid frame. Frame is made of two parts, lower reactive part is made in form of a structure of spherical shape with internal congruent spherical resonant cavity, formed by rigid spherical enclosure, equidistant outer perforated spherical shell connected with top active part is made in form of a rigid perforated cylindrical shell with perforated cover and solid base. Cavity of cylindrical shell is filled with sound absorbing material. Connection of top and bottom parts of sound absorber is made by resilient damping element ensuring dampening of HF oscillations. To perforated cover of perforated cylindrical shell element is pivotally connected, using it framework is secured to required facility, for example, to ceiling of production room. Spherical resonance cavity of reactive part of frame is rigidly connected at least one sleeve with axial bore that doubles as neck of Helmholtz resonator with external perforated spherical enclosure. Space between them is filled by sound absorber. At least one spiral acoustic absorbing element in form of a cylindrical coil spring enclosing shell is mounted around perforated cylindrical shell. Screw sound-absorbing element is made as a hollow screw sound-absorbing element made up by outer and inner screw surfaces forming a cavity. Space formed by outer and inner surfaces of screw is filled with sound-absorbing material having density less than that of screw sound-absorbing element.EFFECT: higher efficiency of noise absorption by expanding frequency range and secondary absorption of sound waves reflected from sound absorber.1 cl, 5 dwg |
