RU2723868C1 - Method of repairing articles from polymer composite materials with one-side access to repair area - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to the technology of repairing articles from polymer composite materials. Technical result is achieved by a method of repairing monolithic articles from polymer composite materials, wherein boundaries of the damage area are determined, and the damaged area is cut to form a through hole. At that, in preparation of repair zone, stepped recess is made at installation of patch layers along edge of through hole. Base contour consisting of fabric impregnated with glue to ensure tightness of bottom part of damage is laid along contour of stepped recess. In middle part of fabric there is an adhesive lens made of a mixture of glue and separate fibres of fabric, and fabric impregnated with glue, which is the first layer of compensating patch, laid over glue lens, by means of which the surface of the compensating patch layer is levelled, for subsequent, after hardening of the base layer, grinding of the conical cavity, in which layers of compensating patch are laid, which are hardened under the vacuum bag.EFFECT: technical result is possibility of repair of said articles from polymer materials without their dismantling.1 cl, 9 dwg

Description

The invention relates to a technology for repairing polymer structures, mainly large-thickness sheets or monolithic panels of polymer composite materials with a one-sided approach, for example, aircraft wing panels. In the method of repairing monolithic structures, the boundaries of the damage zone and the through cutout are determined, the damaged zone is cut out with the formation of a through hole, and then a step recess is cut along the contour of the through hole to form the base layer of the patch, which ensures the tightness of the bottom of the defective zone, consisting of two layers of fabric impregnated with glue and an adhesive lens between them, made of a mixture of glue and individual fibers of the fabric. The base of the sealed layer of the bottom part of the damage is formed from the first fabric layer, on top of which a patch layer is laid, to align which an adhesive lens is laid between the fabric layers from a liquid mixture of glue and individual fabric fibers, the lens curvature is determined "in place". After curing the base layer of the patch, grinding of the conical recess is carried out, in which the patch is assembled, made of separate layers of the prepreg, cured by vacuum pressure. Implementation of the claimed method for repairing monolithic panels of polymer composite materials allows the repair of defects of any size with high efficiency in the conditions of operating organizations, including without dismantling the units from the aircraft.

The invention relates to a technology for repairing monolithic panels of polymer composite materials, mainly thick-walled sheets or monolithic panels with a one-sided approach, for example, aircraft wing panels.

A known method of repairing monolithic panels of polymeric materials with a one-sided approach to the damage zone, proposed by specialists of one of the well-known aircraft developers.

оборота и прижимается к недоступной поверхности ремонтируемой панели с помощью пружинящей стальной пластины, которая и обеспечивает технологическое давление, необходимое для приклеивания изнутри монолитной панели опорного слоя заплаты. По-видимому, вследствие проблемы с герметичностью опорного слоя заплаты из-за отверстия для крепежного приспособления, процесс формования заплаты после приклеивания опорного слоя заплаты проводится в 3 этапа, первый из которых должен обеспечить герметичность донной части повреждения. Указанный способ ремонта имеет ряд существенных недостатков, в том числе: 1) состояние внутренней поверхности панели, недоступной для внешнего наблюдателя, к которой предполагается приклеивать опорный слой заплаты, неизвестно, и, соответственно, без специальной подготовки этой поверхности склеивание может не произойти; 2) при указанном способе установки опорного слоя возможно неправильное распределение клея на склеиваемой поверхности опорного слоям, что может существенно ухудшить характеристики клеевого соединения; 3) угол конуса углубления, вышлифовываемого для выкладки слоев заплаты, составляет в реальности около 1,5°, что обуславливает очень низкую эффективность от использования пружинящей прижимной пластины (деформация пружинящей пластины и, соответственно, величина давления на поверхность скоса минимальны); 4) трудоемкость предлагаемого способа ремонта очень высока вследствие тройного цикла формования заплаты.According to this repair method, a conical oval recess is cut around a defect (through hole) in which the largest diameter of the oval through hole must be larger than the smallest diameter of the repair patch. Then, the support layer of the repair patch together with the spring steel plate is fixed on the temporary mounting device, the edges of the spring plate are lifted and glue is applied to the surface of the support layer of the patch from the side of its contact with the inner surface of the repaired panel, then the support patch layer, lubricated with glue, is installed through the oval hole from the back (inaccessible) side of the panel, where it rotates to

turn and is pressed against the inaccessible surface of the repaired panel using a spring steel plate, which provides the technological pressure necessary for gluing the inside of the monolithic panel of the support layer of the patch. Apparently, due to a problem with the tightness of the patch backing layer due to the hole for the fastening device, the process of forming the patch after gluing the backing patch layer is carried out in 3 stages, the first of which should ensure the integrity of the bottom of the damage. The specified repair method has a number of significant drawbacks, including: 1) the state of the inner surface of the panel, inaccessible to the external observer, to which it is supposed to stick the support patch layer, is unknown, and, accordingly, gluing may not occur without special preparation of this surface; 2) with the specified method of installing the backing layer, improper distribution of glue on the bonded surface of the backing layers is possible, which can significantly impair the characteristics of the adhesive joint; 3) the angle of the cone of the recess, polished to lay out the layers of the patch, is in reality about 1.5 °, which leads to very low efficiency from the use of a spring pressing plate (deformation of the spring plate and, accordingly, the pressure on the bevel surface is minimal); 4) the complexity of the proposed method of repair is very high due to the triple cycle of molding the patch.

A known method of repairing monolithic panels of polymeric materials with a one-sided approach to the damage zone (RF patent No. 2176954 class. In 29 C 73/10, 73/26).

In accordance with this method, the boundaries of the damage zone are determined, the damaged zone is cut out with the formation of a through hole, a patch is made of successive layers of adhesive prepreg, each subsequent layer being smaller than the previous one by the amount of overlap, and the middle part of the patch located in the through hole are pre-cured by heating and compression by means of a calibrated clamp outside the repair zone, and when gluing the patch into the damage zone, it is laid down in minimal layers, while the edges of the patch remaining uncured, protruding beyond the through hole contour, are laid on the bevel surface of the hole in the damage zone. Repair of a structure made of composite material by the described method can be carried out mainly under the influence of excessive pressure on a limited section of the composite panel, which can lead to mechanical damage, moreover, it is complicated by the need for reliable fixation of the device that provides excessive pressure on large panels, for example, airplane wing coffers .

The technical result of the present invention is to avoid the disadvantages mentioned above, and to create such a technology that, with relative ease of implementation, would ensure effective repair of defects of any size on panels of polymer materials of large thickness using known and widely used technological methods, equipment and snap.

The technical result is achieved due to the fact that in the method of repairing monolithic structures, the boundaries of damage and the through cutout are determined, as well as the contour of the circular through-hole step recess along the edge of the through cutout for subsequent molding in the through step-by-step recess and in the through hole of the base layer of the patch, ensuring the tightness of the bottom part a defect consisting of two layers of fabric impregnated with glue and an adhesive lens between them, made of a mixture of glue and individual fibers of the fabric, the base of the sealed layer of the bottom of the damage being formed from the outer layer of the fabric, and the second layer of fabric is the basis for the subsequent laying out of the compensating repair patch in a conical recess, performed in the damaged area of the skin.

In more detail, damage repair is shown in the drawings, where:

in FIG. 1 shows a defect and a contour of a cut-out of a through hole;

in FIG. 2 shows the formation along the perimeter of the through cutout of a stepped recess; laying in the area of damage to the tissue layer,

in FIG. 3 shows the layout in the stepped recess of the first part of the base layer, namely the fabric layer, which is the basis of the sealed layer of the bottom of the damage;

in FIG. 4 shows the placement on a tissue layer, which is the basis of a sealed layer of the bottom of the damage, an adhesive lens from a mixture of glue and chopped fiber;

in FIG. 5 shows the placement on the fabric layer, which is the basis of the sealed layer of the bottom part of the damage, and an adhesive lens from a mixture of glue and fiber from the fabric of the second fabric layer impregnated with glue, which is the second part of the base patch layer;

in FIG. 6 shows the location in the damage zone of the conical recess, performed after curing of the base layer for assembly-laying layers of the compensating patch;

in FIG. 7 shows the location of the patch layers in a conical recess in the damage zone;

in FIG. Figure 8 shows the process of curing the patch layers under vacuum pressure and heating (if necessary) in a vacuum bag.

In FIG. 9 shows a final repair patch molded under a vacuum bag.

The method is as follows.

The boundaries 1 of the damage are determined (Fig. 1), after which a through hole is cut out in the damaged area along the outlined contour 1 (Fig. 2) with the formation of a stepped recess 2 around the hole. A layer of fabric 3 is laid along the contour of the stepped recess 2 (Fig. 3), impregnated with glue, in the middle part of layer 3 (Fig. 4), an adhesive lens 4 is placed, on top of which a patch patch layer 5 (Fig. 5) is laid and aligned, also impregnated with glue. After curing the glue, which is impregnated with the fabric layers that make up the base layer, around the stepped recess 2, a conical surface 6 (Fig. 6) is ground to assemble layers 7 (Fig. 7), which are subsequently cured under a vacuum bag 8 (Fig. 8) with the purpose of obtaining a compensating patch 9 (Fig. 9).

The number of layers n of the compensating patch is determined by the ratio

n = H _n / δ _m

where H _n is the thickness of the composite panel in the damage zone;

δ _m - the thickness of the monolayer patch without glue.

The overlap of the patch layers Δ is determined by the ratio

Δ = L / n,

where L is the length of the bevel of the conical recess in the damage zone. The patch layers in the conical recess are laid out from smaller to larger or, when assembling the patch outside the repair zone, the patch layers are laid out on the separating film in the reverse order from the larger to the smaller one, taking into account the specified overlap Δ between the layers, after which the assembled patch is turned over and placed into a conical recess in the damage zone.

Implementation of the claimed method allows the repair of defects of any size with high efficiency.

The proposed method of repairing products made of polymeric materials allows, without dismantling and disabling the facility, to repair using known, practically tested, technological methods and tools. The method ensures the preservation of the operational properties of monolithic structures and the optimal strength characteristics of the repaired area of the surface of the product.

Claims (1)

A method of repairing monolithic products from polymer composite materials, in which the boundaries of the damage zone are determined, the damaged zone is cut out with the formation of a through hole, characterized in that when preparing the repair zone for installing patch layers along the edge of the through hole, a step recess is made, a base step is laid along the contour of the step recess a layer consisting of a fabric impregnated with glue, ensuring the tightness of the bottom of the damage, in the middle part of which is placed an adhesive lens made of a mixture of glue and individual fibers of the fabric, and fabric impregnated with glue, which is the first layer of compensating patch, laid on top of the adhesive lens, by means of which the surface of the compensating patch layer is leveled, for subsequent grinding of the conical recess after the base layer has cured, in which the compensating patch layers cured under the vacuum bag are laid out.

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