RU2176954C1 - Device for repair of items of polymeric materials - Google Patents

Abstract

FIELD: procedure of production and repair of items of polymeric materials, mainly of sheets or monolithic panels with one-sided approach, for example, of aircraft wing panels. SUBSTANCE: the boundaries of the damage zone are determined, the damaged zone us cut out with formation of a through hole. A cover plate of successively superposed layers of adhesive prepreg of the respective shape are manufactured and successively cemented in the zone of item damage with observation of the heating and pressure condition. The dimension of each subsequent layer of adhesive prepreg should be less than the previous one by the value of overlap. The middle part of the cover plate positioned in the through hole is preliminarily cured by heating and compression by means of a calibrated cramp outside the repair zone. At cementation of the cover plate in the zone of damage it is laid with the minimum layers down. The cover plate edges remained non-cured, projecting from the contour of the through hole, are laid on the surface of the bevel of the damage zone hole. EFFECT: enhanced efficiency of repair of defects of any dimensions. 7 dwg

Description

 The invention relates to a technology for the production and repair of products from polymeric materials, mainly sheets or monolithic panels with a one-sided approach, for example, aircraft wing panels.

 A known method of repairing the walls of containers, which is a three-layer structure with shells of fiberglass sheet and a middle part of wood (German patent N 2758892 class. 32 32 35/00).

 In accordance with this method, the damaged material is cut out of the defective shell in the form of a rectangle with bevels at the edges. In the formed recess, the bottom of which is the wooden part of the wall, a cold-cured liquid epoxy resin is poured flush with the outer surface of the fiberglass shell. Repair of panels with a one-sided approach (for example, wing panels) by pouring a defective area with liquid resin is not possible due to the lack of support from below. Carrying out repairs in this way the lower wing panels is also not possible.

 A technical solution is known for repairing products made of polymeric materials, including determining the boundaries of the damage zone, cutting out the damaged zone with the formation of a through hole and lining of the corresponding shape, gluing the latter into the damage zone in compliance with the pressure and heating regime (AS USSR No. 1359142, class. 5 B 29 C 73/26, publ. 1987).

 But such a method of repairing products made of polymer materials is possible if the defects are small. To process defective areas, a set of special tools of several sizes and only round shapes is required. In addition, there is a likelihood that the edges of the patch do not fit snugly against the edges of the damaged area of the object due to an error in processing with their respective spherical surfaces of the tools.

 There is another method for repairing products made of polymeric materials, in which 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 of the corresponding shape and glued to the damaged zone of the product in compliance with the heating mode and pressure (patent RU 2039655, class B 29 C 73/14, B 32 B 1/10, publ. 1995).

The disadvantages of this repair method include the angle specified by the developers of the bevel angle of the holes in the defective skin zone (35-45 ^o ), which is the determining factor for the proposed method, which significantly differs from the generally accepted optimal value (3 ^o ) obtained experimentally and by calculation. Milling a groove in a filler with such a bevel angle for installing additional overlays to the upper and lower skins will lead to destruction of the filler near the edge of the hole over a considerable area, and overlays with such bevels for the upper and lower skins made in advance or assembled from prepreg layers in the repair zone, cannot be inserted into the panel. In this regard, the fundamental thesis of developers about the introduction of internal repair linings for the upper and lower skin is losing its meaning. Instead of overlays offered by the developers, the technology for repairing polymeric materials developed in the USA more than 20 years ago provides for a slight thickening of patches in the repair zone due to several additional layers of prepreg.

 The technical result of the present invention consists in the simplicity of the method, the effectiveness of the repair of any size on units of any thickness.

 The technical result is achieved due to the fact that in the method of repairing products made of polymeric materials, the size of each subsequent layer of adhesive prepreg is selected to be smaller than the previous one by the amount of overlap, and the middle part of the lining located in the through part of the hole is pre-cured by heating and compression using a calibrated clamp outside the repair zone, and when gluing the lining in the damage zone, it is laid down with minimal layers, while the edges of the lining, remaining uncured, protruding beyond the well contour a hole, laid on the surface of the bevel of the hole in the damage zone.

In more detail, repair of a damaged surface is shown in the drawings, where:
in FIG. 1 shows a defect and a contour of a notch;
in FIG. 2 - cutting a conical surface along the edge of the defective zone;
in FIG. 3 - template for cutting layers of overlays;
in FIG. 4 - cut out layers of the lining;
in FIG. 5 - curing of the middle part of the lining;
in FIG. 6 - node A of FIG. 5;
in FIG. 7 - gluing the lining in the repaired area of the product.

 The method is as follows.

The place of damage and its boundaries 1 (Fig. 1) are determined, after which a through hole is cut out in the damaged area along the outlined contour 1 (Fig. 2) with the formation of a conical surface 2 around the hole, for example, using an abrasive wheel 3 fixed in a pneumatic drill 4 Lay out and cut out according to the templates from thick paper 5 (Fig. 3) the layers of adhesive prepreg 6 of the overlay, and each subsequent layer should be less than the previous one by the overlap Δ calculated by the formula
Δ = L / n,
where L is the length of the bevel of the recess in the panel;
n - is determined by the ratio of the thickness of the repaired panel to the thickness of the prepreg monolayer.

The number of prepreg layers is determined from the ratio
n = T _p / t _m ,
where T _p is the thickness of the repaired panel;
t _m is the thickness of the monolayer of fabric, which is the basis of the adhesive prepreg.

 The cut out prepreg layers are placed on a release film 7 (Fig. 4) placed on an aluminum alloy substrate 8, the layers being arranged from larger to smaller to ensure uniform overlap of the layers. After assembling the pads on top of the smallest layer lay the release film 9 (Fig. 5), cover with a gasket 10 made of aluminum alloy. Next, the middle part of the lining located in the through hole is pre-cured by heating and compression by means of a calibrated clamp 11 outside the repair zone. In a calibrated clamp, the smallest layers are facing the heater 12. Heating is controlled by a thermocouple 13 placed between the gasket 10 and the release film 9 (Fig. 6). Due to the low thermal conductivity of the layers of the adhesive prepreg 6, heat does not propagate outside the heating zone.

 The magnitude of the compression force of the layers of the prepreg 6 pads in the clamp 11 is regulated and corresponds to the pressure of molding of the polymer material in an autoclave. The middle part of the patch cures, and the size of the cured portion is greater than or equal to the size of the through hole in the defective area.

 Next, the overlay is laid in the damaged area 1 of the product 14 (Fig. 7) with the minimum layers downward, providing pressure with the air bag 15 through the heat insulator 16 and the heater 17. In this case, the edges of the overlay remaining uncured, protruding beyond the contour of the through hole, are laid on the surface of the bevel of the hole damage zones and carry out gluing of the lining in the damaged area of the product. The edges of the lining due to the low thermal conductivity of the polymers, remaining uncured, easily, without adjustment and gaps, abut the surface of the bevels of the hole in the damaged area. Bonding may also be carried out using a vacuum bag.

 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 carry out repairs by known means using simple equipment. The method provides a high-precision selection of the prepreg layers and optimal strength characteristics of the repaired area of the object surface.

Claims (1)

 A method of repairing products from polymeric materials, in which 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 from successively superimposed adhesive prepreg layers of the corresponding shape and glued sequentially into the damage zone of the product in compliance with the heating and pressure conditions, different the fact that the size of each subsequent layer of adhesive prepreg is chosen smaller than the previous one by the amount of overlap, and the middle part of the lining, located in the openings 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 contour of the through hole, are laid on the bevel surface of the hole in the damage zone .

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