UA64980C2 - Method for repair of acoustic cellular panel - Google Patents

Abstract

A method for repair of acoustic cellular panel with at least setting and duct-formation perforated linings connected to the cellular filling with detachment of those linings from the cellular filler is in the fact that the detachment of the linings is removed by tightening and fixing the last ones in the panel by means of fixation part. The fixation part is made of a section of wire, first one put it into U-like shape, and the free ends of the U-like fixation part are placed to the openings of the lining at the place of detachment through the panel with fixation with tension relative to the panel.

Description

of the fastening part, the following improvements were made.

The fastening part is made from a piece of wire, having previously given it a U-shaped shape, and the free ends of the obtained U-shaped fastening part are inserted into the holes of the cladding at the place of peeling through the panel and fixed with tension relative to the panel. With reliable fastening, this ensures a minimal increase in the mass of the panel after repair, as well as a less dangerous effect on the nodes of the tract in case of destruction of the fastening structure.

The mentioned free ends of the U-shaped fastening part for greater reliability of fastening are performed, as an option, together with the flat base perpendicular to the latter, and the free ends are made flat. Holes are made in the flat base of the U-shaped fastening part to prevent this base from covering the perforation holes of the cladding, which ensures a minimal reduction in the noise-absorbing characteristics of the acoustic panel due to the preservation of the perforation area.

The fastening part can be fixed by twisting the free ends or bending the latter into the body of the panel.

Through the holes of the cladding in the panel, holes are additionally drilled for each of the mentioned free ends of the fastening part. This ensures a more technological introduction of the ends of the fastening part into the body of the panel without chipping the cellular aggregate.

Before inserting the free ends of the U-shaped fastening part into the drilled holes and fixing them in the panel, glue is injected for additional fixation, which additionally increases the reliability of the structure, in the places where the cladding peels off from the cellular aggregate.

A thrust plate is additionally installed on the landing panel, in which holes are drilled for the free ends of the fastening part, coaxially aligned with the previously drilled holes in the panel. The support plate is fixed with glue to the landing panel, which also increases the reliability of the structure.

If there is insufficient space for repairs between the landing skin and the engine body, recesses are made in the cellular aggregate at the place of installation of the mentioned thrust plate. A substrate is additionally installed in the made depression. The mentioned substrate is fixed with glue to the cellular aggregate.

All this together provides the aforementioned technical results of the proposed solution.

The essence of the claimed technical solution is explained by the drawings, where:

Fig. 1 shows a longitudinal section of an acoustic honeycomb panel with delaminations;

Fig. 2 shows a three-dimensional view of an acoustic honeycomb panel with a U-shaped fastening part and a thrust plate;

Fig. 3 shows a three-dimensional view of an acoustic cellular panel with a U-shaped fastening part, a thrust plate and a lining under the latter;

Fig. 4 shows a longitudinal section of an acoustic honeycomb panel, repaired according to the technical solution that is claimed, in the presence of a gap between the engine body and when fixing the free ends of the U-shaped fastening part with a bend;

Fig. 5 shows a longitudinal section of an acoustic cellular panel, repaired according to the technical solution that is claimed, when making a recess in the cellular aggregate and when fixing the free ends of the U-shaped fastening part with a bend;

Fig. 6 shows an enlarged fragment of the longitudinal section of the repaired acoustic honeycomb panel when fixing the free ends of the U-shaped fastening part with a twist;

Fig. 7 shows an enlarged fragment of the longitudinal section of the repaired acoustic cellular panel when making a recess in the cellular filler while fixing the free ends of the U-shaped fastening part with a twist;

Fig. 8 shows an enlarged view A (see Fig. 4) of the repaired acoustic honeycomb panel when the free ends of the U-shaped fastening part are fixed with a bend;

Fig. 9 shows an enlarged view of A' (see Fig. b) of the repaired acoustic honeycomb panel when fixing the free ends of the U-shaped fastening part with a twist;

Fig. 10 presents a three-dimensional image of a U-shaped fastening part with a flat base with holes and flat free ends;

Fig. 11 shows a blank for obtaining a U-shaped fastening part with a flat base with holes and flat free ends (see Fig. 10);

Fig. 12 shows an enlarged view B (see Fig. 4) of the repaired acoustic honeycomb panel when using a U-shaped fastening part;

Fig. 13 presents an enlarged view B (see Fig. 4) of the repaired acoustic honeycomb panel using a U-shaped fastening part with a flat base and holes in it.

The method of repairing an acoustic cellular panel is implemented as follows.

The acoustic cellular panel, which is sent for repair, consists of a landing skin 1 (see Fig. 1), which is located at a distance "1" from the engine body 2, and a tract forming skin C, between which are fixed layers of cellular aggregate 4, which in its the row is divided by intermediate cladding 5.

The above-mentioned tract-forming cladding C has a uniform perforation 6 over its entire area and has a separation 7 of the amount "b" from the cellular aggregate 4.

The repair consists in removing delamination 7 mechanically, if the amount of delamination "b" allows it.

After cleaning the exfoliation site 7 from dirt and drying the panel, holes 8 are drilled through the four perforation holes 6 of the tract forming skin C through the intermediate skin 5 and the landing skin 1 (see Fig. 2).

Then glue that hardens at room temperature is injected into the place of peeling 7.

On the side of the landing skin 1, in order to create uniform pressure on this skin, a thrust plate 9 (see Fig. 2) with four holes 10 is installed so that the holes 10 of the plate 9 coincide with the holes 8 previously drilled in the landing skin 1. At the place of contact of the plate 9 and the landing panel 1 is also preliminarily applied with glue that hardens at room temperature for better fixation of the specified plate 9.

On the side of the tractive skin C through the through holes 8 in the skins 5 and 1, holes 6 in the skin C and holes 10 in the plate 9, the free ends 11 of the fastening part 12 (see Fig. 2) are introduced in pairs and fixed with tension.

The above-mentioned fastening part 12 is made from a pre-calculated length of a piece of metal wire in the following way.

The ends of the wire segment of the measured length are bent twice at a right angle on both sides of the base 13 to form a U-shaped part. Thus, the fastening part 12 will have a base 13 and free ends 11 (see Fig. 2).

The fastening part 12 is fixed after inserting the ends 11 into the panel or by bending the free ends 14 protruding beyond the stop plate 9 from the side of the landing panel 1 into the body of the landing panel 1 (see Figs. 4 and 5) or by twisting its ends 14 (see Fig. b and 7).

In this way, the exfoliated tract-forming cladding C is attracted by the fastening part 12 to the cellular aggregate 4 and also additionally fixed with adhesive clamps 15 (see Fig. 4), obtained from the previously introduced glue in the place of exfoliation 7.

The number of fasteners 12 used depends on the peeling area 7 (see Fig. 2).

In the event that the gap "I" between the landing panel 1 and the body 2 is absent or insufficient for repair (see Fig. 1), before the introduction of the fastening part 12, perform the following operations.

In the cellular aggregate 4, on the side of the landing paneling 1, a recess 16 (see Fig. 3) with a depth of "H" is made, where, instead of a part of the removed landing paneling 1, a lining 17 is installed on the glue that hardens at room temperature. The latter is made with the dimensions (diameter or linear), sufficient to install the thrust plate 9. Moreover, the holes 18 in the substrate 17 and the holes 10 in the thrust plate 9 connect coaxially.

Thus, the free ends 11 of the fastening part 12 are inserted through the holes 6 in the tractive skin 3, the holes 18 of the substrate 17 and the holes 10 of the thrust plate 9 (see Fig. 3) and the protruding ends 14 of the fastening part 12 (see Figs. 5 and 7 ) are fixed by the methods described earlier.

By performing the above operations, a gap between the landing skin 1 and the body 2 is provided (see

Fig. 5 and 7).

The repaired panel in its longitudinal section will have the appearance shown in Fig. 4 or 5 (6 or 7), and on

Fig. 8 or 9 - views from above and Fig. 12 - a view from below.

If it is necessary to eliminate peeling of a larger area, instead of the U-shaped fastening part 12 from the wire segment, it is suggested to use the U-shaped fastening part 19 with a flat base (see Fig. 10), which at the same time can be used in any cases to fix the peeling , but it is a little more complex in design.

The above-mentioned fastening part 19 with a flat base is made in the following way.

A part is cut from the sheet blank, the configuration of which is shown in Fig. 11, as a result of which the fastening part 19 will have a flat base 20 (see Fig. 10), which has drilled holes 21, and free ends 22 that bend at right angles to the base 20 along lines "11" and "2" (see Fig. 11).

The number of free ends 22 and holes 21 corresponds to the peeling area 7 and the number of perforation holes b (see Fig. 2).

The mentioned holes 21 are made to prevent the flat base 20 from overlapping the perforation holes 6 in the tract-forming cladding C (see Fig. 13) when installing the fastening element 19, for which the axes of the holes 21 are aligned with the axes of the holes 6.

The free ends 22 of the fastening part 19, intended for insertion into the panel, can be made in the form of plates, as shown in Fig. 10, or in the form similar to the free ends 11 of the fastening part 12 from a wire segment (see Fig. 2), with the same sizes.

In the case of using the fastening part 19 instead of the fastening part 12, the repair operations and their sequence do not change.

The repaired panel in its longitudinal section when using the fastening part 20 will have the view shown in Fig. 4 or 5 (6 or 7), and in Fig. 8 or 9 - views from above and Fig. 13 - a view from below.

In this way, the proposed technical solution is implemented.

The applicability of the proposed repair method is confirmed by the positive results of tests of experimental samples of acoustic honeycomb panels, repaired according to the proposed technical solution, which were installed on engines of ZMKB "Progress" of the D18T family, in flight modes on airplanes

An-124 "Ruslan" and An-225 "Mriya", and after 6,000 hours of operation, they retained their performance.

At this time, the described technical solution is intended for use in production.

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