| 摘要 |
942,596. Laminates. SOC. APPLICAZIONI GOMMA ANTIVIBRANTI S.p.A. June 28, 1961 [Jan. 21, 1961], No. 23404/61. Heading B5N. A sound-absorbing panel includes a foraminated plate 10, one surface of which is covered with a porous layer 15 which is formed with a plurality of flared apertures 16, 17 which extend therethrough, the end of each of said apertures which is of least cross-sectional area being in register with at least one of the holes 14 in the plate 10. As shown, Fig. 1, a foraminous element 10 is stamped from aluminium sheet to form a rectangular tray having bottom wall 11, side walls 12 and numerous uniformly distributed holes 14 in bottom 11. Porous layer 15 comprising a mat of mineral wool is secured, e.g. glued, to bottom 11 to form a unitary structure with the tray. In layer 15 numerous apertures 16, 17 are provided flaring towards the upper surface of the layer, aperture 16 being centred on one of the holes 14 while aperture 17, which may be elliptical in crosssection, embraces two of the holes 14. The composite sound-absorbing panel may be suspended from a ceiling 18 at an optimum distance by means not shown. The thickness of the porous layer should not be less than 1 centimetre and is preferably 1.5 to 2 cms. The porous layer 15 may comprise a stack of elemental layers 15a, 15b, 15c, &c. (as shown in Fig. 2) which may be adhered together, e.g. with a sprayed vinyl polymer, each consisting of a mat of fibres and having cylindrical apertures 16a, 16b, 16c, &c. of increasing cross-sectional area punched therein so as to form flared apertures in the composite layer. |
