Method and apparatus for acoustic perforation of core sandwich panels
An acoustic perforation method and assembly for forming holes or perforations into a face sheet of a sandwich panel without damaging a honeycomb core thereof. The method may include photographing or otherwise scanning the face sheet bonded to the honeycomb core after cure, then detecting locations of cell walls of the honeycomb core via image processing or analysis of scan data obtained. For example, discolorations on the face sheet or coatings applied thereto may indicate locations of the cell walls of the honeycomb core. A perforation pattern may then be generated or altered based on the detected locations of the cell walls, and a perforation device may be commanded to perforate the face sheet in accordance with the perforation pattern at locations where the cell walls are not located.
1. A method for perforating a sandwich panel including a face sheet having an outer surface and an inner surface, the inner surface being bonded to a core having a plurality of cell walls, the method comprising:
receiving data representative of the outer surface of the face sheet from an imaging device, wherein the data is a digital image from the imaging device, wherein the face sheet has a surfacer coating applied thereto, wherein variations due to pressure by the honeycomb core during curing of the sandwich panel causes a visible pattern in the surfacer coating corresponding to locations of the cell walls,
detecting locations of the cell walls of the core based on at least one of color, hue, or brightness in the digital image, and
commanding a perforation device to perforate the face sheet in locations where the cell walls are not located, based on the detecting step.
2. The method of claim 1 , further comprising a step of a processor generating or altering a perforation pattern to be applied to the face sheet based on detected locations of the cell walls, such that any perforations of the perforation pattern corresponding in location with the cell walls is omitted from the generated or altered perforation pattern, wherein the commanding step is performed by the processor in accordance to the generated or altered perforation pattern.
3. The method of claim 2 , wherein the perforation device comprises a cutting tool and one or more actuators for positioning the cutting tool relative to the face sheet, wherein the step of commanding the perforation device to perforate the face sheet includes commanding the actuators to relocate the cutting tool to a next position on the face sheet to be perforated according to the generated or altered perforation pattern and commanding the cutting tool to form the perforation at the next position on the face sheet.
4. The method of claim 1 , further comprising a step of a processor generating a repeating perforation pattern to be applied to the face sheet based on detecting locations of the cell walls, wherein the repeating perforation pattern includes a predetermined number of perforations placed within each of a plurality of cells determined by the locations of the cell walls, wherein the commanding step is performed by the processor in accordance with the generated repeating perforation pattern.
5. The method of claim 1 , wherein the perforation device comprises a cutting tool and one or more actuators configured for positioning the cutting tool relative to the face sheet, wherein the imaging device is physically coupled to the cutting tool and is positionable therewith via the actuators, further comprising repeating the detecting and commanding steps for a plurality of pre-determined perforation locations, wherein the step of commanding the perforation device to perforate the face sheet in locations where the cell walls are not located includes:
determining if any of the cell walls coincides with a current position of the cutting tool based on at least one of color, hue, or brightness in the digital image from the imaging device,
moving to a next position of the plurality of pre-determined perforation locations if the current position does coincide with any of the cell walls, and
instructing the cutting device to create the perforation at the current position if the current position does not coincide with any of the cell walls.
6. A method for manufacturing a sandwich panel, the method comprising the steps of:
placing or attaching at least one face sheet against edges of cell walls of a honeycomb core, with the face sheet sandwiched between the honeycomb core and a surfacer coating applied to the face sheet;
curing the face sheet, the honeycomb core, and the surfacer coating so that variations due to pressure by the honeycomb core causes a visible pattern in the surfacer coating corresponding to locations of the cell walls;
transmitting to a processor an image, from an imaging device comprising a camera or an X-ray device, of the surfacer after curing thereof;
detecting, with the processor, locations of the cell walls of the honeycomb core based on at least one of color, hue, or brightness in the image;
generating or altering, with the processor, a perforation pattern to be applied to the face sheet based on the detected locations of the cell walls, such that any perforations of the perforation pattern corresponding in location with the cell walls is omitted from or relocated within the generated or altered perforation pattern; and
commanding a perforation device to perforate the face sheet in locations where the cell walls are not located, based on the generated or altered perforation pattern.
7. The method of claim 6 , wherein the perforation device comprises a cutting tool and one or more actuators for positioning the cutting tool relative to the face sheet, wherein the step of commanding the perforation device to perforate the face sheet includes commanding the actuators to relocate the cutting tool to a next position on the face sheet to be perforated according to the generated or altered perforation pattern and commanding the cutting tool to form the perforation at the next position on the face sheet.
8. The method of claim 6 , wherein the generating or altering step comprises generating the perforation pattern as a repeating perforation pattern including a predetermined number of perforations placed within each of a plurality of cells determined by the locations of the cell walls.
9. The method of claim 1 , wherein the outer surface of the face sheet is opaque.
10. The method of claim 1 , wherein the face sheet comprises carbon composite material.
11. The method of claim 1 , further comprising perforating the face sheet at the locations where the cell walls are not located.
12. The method of claim 1 , further comprising positioning the perforation device over the face sheet with the imaging device attached to the perforation device, and repositioning the perforation device if a position of the perforation device is above one of the cell walls of the core.