METHODS, PRECURSORS AND ABRASIVE BLASTING MASKS FOR MANUFACTURING NOISE ATTENUATING DEVICES
Noise attenuating devices and methods, precursors and abrasive blasting masks for manufacturing noise attenuating devices are disclosed. An exemplary method disclosed herein includes bonding a facing sheet of the noise attenuating device to a cellular core and then perforating the facing sheet. Perforating the facing sheet may be performed by abrasive blasting using a mask configured to prevent the abrasive blasting of an underlying structure.
1 . A method for manufacturing a noise-attenuating device comprising a facing sheet having an outer side and an inner side and a cellular core, the method comprising:
bonding the facing sheet to the cellular core so that the inner side of the facing sheet faces a first side of the cellular core; and
after bonding the facing sheet to the cellular core, perforating the facing sheet.
2 . The method as defined in claim 1 , further comprising bonding a backing plate to a second side of the cellular core before perforating the facing sheet, the second side being opposite to the first side.
3 . The method as defined in claim 1 , wherein bonding the facing sheet to the cellular core comprises applying an adhesive film to the inner side of the facing sheet and then joining the facing sheet and the cellular core.
4 . The method as defined in claim 3 , wherein the adhesive film uniformly covers a region of the inner side of the facing sheet where the region has an area that covers more than one cell of the cellular core.
5 . The method as defined in claim 3 , further comprising forming one or more holes through the adhesive film when perforating the facing sheet.
6 . The method as defined in claim 1 , wherein perforating the facing sheet comprises abrasive blasting the facing sheet.
7 . The method as defined in claim 6 , further comprising masking the outer side of the facing sheet at locations where the facing sheet is to remain imperforated.
8 . The method as defined in claim 6 , further comprising masking the outer side of the facing sheet at locations of the facing sheet overlapping any walls of the cellular core in order to substantially prevent the walls of the cellular core from being abrasively blasted during perforation.
9 . The method as defined in claim 6 , further comprising producing an abrasive blasting mask by:
applying a photosensitive masking material on the outer side of the facing sheet; and
selectively exposing the photosensitive masking material to light configured to activate the photosensitive masking material.
10 . The method as defined in claim 9 , wherein selectively exposing the photosensitive masking material to light comprises projecting one or more images on the photosensitive masking material, the one or more images being configured to cause the formation of one or more holes in the photosensitive masking material in a region not overlapping the structure of the cellular core and substantially avoid the formation of holes in the photosensitive masking material in a region overlapping a structure of the cellular core.
11 . The method as defined in claim 10 , further comprising using data representative of a position of at least part of the cellular core to generate data representative of the one or more images.
12 . The method as defined in claim 11 , wherein the one or more images comprise a single image incorporating both the data representative of the position of at least part of the cellular core and data representative of one or more holes desired in the facing sheet.
13 . The method as defined in claim 12 , wherein the single image defines an outline of one or more walls of the cellular core and the one or more holes desired in the facing sheet.
14 . The method as defined in claim 11 , wherein the one or more images comprise:
a first image incorporating data representative of one or more holes desired in the facing sheet; and
a second image incorporating the data representative of the position of at least part of the cellular core.
15 . The method as defined in claim 14 , further comprising projecting the first image and the second image sequentially.
16 . The method as defined in claim 11 , wherein the data representative of the position of at least part of the cellular core comprises a thermographic image of a precursor to the noise attenuating device comprising the cellular core.
17 . The method as defined claim 11 , wherein the data representative of the position of at least part of the cellular core comprises an X-ray image of a precursor to the noise attenuating device comprising the cellular core.
18 . The method as defined in claim 1 , further comprising, after perforating the facing sheet, bonding a layer of porous material to the outer side of the facing sheet.
19 . A precursor for manufacturing a noise attenuating device, the precursor comprising:
a cellular core having a first side; and
an imperforated facing sheet having an outer side and an inner side, the imperforated facing sheet being bonded to the first side of the cellular core so that the inner side of the facing sheet faces the first side of the cellular core.
20 . The precursor as defined in claim 19 , comprising a backing plate bonded to a second side of the cellular core, wherein the second side is opposite to the first side.
21 . The precursor as defined in claim 19 , further comprising an adhesive film disposed on the inner side of the facing sheet.
22 . The precursor as defined in claim 21 , wherein the adhesive film uniformly covers a region of the inner side of the facing sheet where the region has an area that covers more than one cell of the cellular core.
23 . The precursor as defined in claim 19 , further comprising a mask overlaying the outer side of the facing sheet and configured to substantially prevent abrasive blasting of the facing sheet at locations where the facing sheet is to remain imperforated.
24 . The precursor as defined in claim 19 , further comprising a mask overlaying the outer side of the facing sheet and configured to substantially prevent abrasive blasting of the facing sheet at locations of the facing sheet overlapping any walls of the cellular core.
25 . The precursor as defined in claim 19 , further comprising:
a first mask portion overlaying the outer side of the facing sheet and comprising a plurality of holes configured to permit passage of abrasive material through the mask to perforate the facing sheet; and
a second mask portion configured to block one or more of the plurality of holes in the first mask portion that overlap walls of the cellular core in order to substantially prevent the walls of the cellular core from being abrasively blasted.
26 . The precursor as defined in claim 19 , wherein the facing sheet comprises a composite laminate.
27 . A noise attenuating device comprising:
a cellular core having a first side;
a perforated facing sheet having an outer side and an inner side, the perforated facing sheet being bonded to the first side of the cellular core so that the inner side of the facing sheet faces a first side of the cellular core; and
an adhesive film disposed on the inner side of the facing sheet where one or more holes extending through the perforated sheet also extend through the adhesive film.
28 . The noise attenuating device as defined in claim 27 , further comprising a backing plate bonded to a second side of the cellular core, wherein the second side is opposite to the first side.
29 . The noise attenuating device as defined in claim 27 , wherein the adhesive film uniformly covers a region of the inner side of the facing sheet where the region has an area that covers more than one cell of the cellular core.
30 . The noise attenuating device as defined in claim 27 , wherein the facing sheet is imperforated at locations of the facing sheet overlapping any walls of the cellular core.
31 . An aircraft comprising the noise attenuating device as defined in claim 27 .
32 .- 46 . (canceled)