RU2560473C2 - Sandwiched panel and method of its production - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, particularly, production of sandwiched panels with light bulky filler from corrugated zigzag-like material. It can be used in aircraft and ship building, etc. Claimed panel comprises linings bonded by composite adhesive with corrugated filler sheet arranged there between with alternating crimps and recesses. Flat side faces are bonded with zigzag-like lines. Cavity between linings and corrugated sheet filler is filled with extra reinforcing filling agent. Support element is composed of foam substrate located on both sides of the panel mid plane for half its height for local support and rigid locking of lateral flat faces and tops of said corrugate sheet filler. Liquid wax if filled in filler recesses on both side of the panel. On extra layer formed after hardening applied is extra reinforcing foam filler. After heating liquid wax is removed.

EFFECT: higher stability of corrugated sheet filler owing to rigid locking of flat side faces and tops of corrugated sheet filler.

2 cl, 9 dwg

Description

The invention relates to the field of engineering and building structures, and in particular to technologies for the production of multilayer panels with a light volume filler from sheet corrugated zigzag material, and can be used in aircraft construction, shipbuilding and other industries.

A multilayer panel is known, comprising upper and lower casing and a zigzag corrugated filler placed between them, deployed on a plane, with side faces at an angle to one another with the formation of alternating protrusions and depressions and having contact areas with upper and lower casing with a light filler of corrugated sheet material. To increase the contact area of the filler with the lower skin, the ribs of the corrugations are made in the form of lenticular elements located at the depressions of the side faces. For the same purpose, with respect to the upper skin, the contact areas are made curved in the form of a composite material located between the side faces of the filler at its vertices. (RF patent No. 2038265, “Multilayer panel”, IPC B64C 3/26, published on June 27, 95).

The disadvantage of this panel is the lack of compressive strength and the likelihood of crack propagation over the entire surface at local loads.

The closest in technical essence and taken as a prototype is a multilayer panel containing outer skin connected with a corrugated filler of a zigzag structure between them with alternating protrusions and depressions placed between them, there is a line perforation on the curved sections of the bend of the filler material, through each hole the adhesive penetrates into the corrugation and forms a drop there, which during the polymerization of glue when connecting the filler with the skin E forms a rivet body and a head (RF Patent №2265552, «sandwich panel", IPC B64C 3/26, published on 10.12.2005, Bul. №34).

The disadvantage of this panel is the lack of compressive strength when using panels in structures subject to power loads, the lack of stability of the flat side faces.

A known method of manufacturing a multilayer panel, including the separate manufacture of skins and filler with their subsequent connection, forming a folded structure of the filler, consisting of a zigzag corrugation, the ribs of which along zigzag lines are made with the possibility of inclination relative to the plane of contact with the skins, then compressing the filler block from the sides to the extremely compressed state of the faces and removal, for example, by grinding to the specified height of the formed inclined steps with the formation of a gap two lateral faces and jumpers in the lower part of the ribs that keep the aggregate intact, and the connection is carried out along the forked ribs formed as a result of grinding (RF Patent No. 2352726, “Multilayer panel and method of its manufacture”, IPC E04B 1/08, B21D 47 / 04, B64C 3/26, published April 20, 2009, bull. No. 11).

The disadvantage of this method is the low strength and stability of the bifurcated ribs resulting from grinding, and the cracks formed between the side faces and jumpers in the lower part of the ribs, and also due to the inability to form supports in the form of local elements to support the flat side faces in the most dangerous sections along the height of the filler, which leads to premature loss of stability and strength in general. In the known method, the loss of stability occurs with the appearance of a single wave, which significantly reduces critical stresses, as well as the complexity of the manufacturing process due to the use of additional grinding or milling operations, which means the use of special additional equipment.

The complexity of the manufacturing process due to the use of additional grinding or milling operations, which means the use of special additional equipment.

The problem to be solved, the invention is aimed at, is to increase the compressive strength and increase the stability of the elements of the sheet corrugated zigzag filler of the multilayer panel at its predetermined weight specific strength.

The technical result achieved by the implementation of the claimed invention is to increase the durability of the multilayer panel due to compressive strength and increase the stability of the sheet corrugated zigzag filler, by rigidly fixing the flat side faces and the vertices of the sheet corrugated zigzag filler of the multilayer panel, at its predetermined weight specific strength.

The specified technical result is achieved in that in a multilayer panel containing sheathing, connected using composite adhesive material with a sheet of corrugated zigzag filler placed between them with alternating protrusions and depressions, the flat side faces of which are interconnected by zigzag lines, it is equipped with a supporting element in the form additional reinforcing filler from hardened foam introduced into the space between the skin and the corrugated sheet zigzag filler and disposed on both sides of the panel middle plane passing through the half of its height.

The technical result is achieved by the fact that in the method of manufacturing a multilayer panel, comprising connecting the skin using composite adhesive material and placing between them a sheet of corrugated zigzag filler with alternating protrusions and depressions, forming flat side faces, on both sides of the panel at the level of one third of its height in the troughs of the sheet corrugated zigzag filler fill in liquid paraffin, which forms, after hardening, an auxiliary layer on which an optional reinforcing filler of foam in liquid state on both sides of the median plane of the panel, passing through half its height, cure the foam to form a backing element that serves as an intermediate additional support for local support of the flat side faces and vertices of the corrugated sheet of zigzag filler, after which the panel is heated to 80-90 ° C, receive paraffin in a liquid state, which is then removed.

Novelty

The proposed method allows you to create intermediate supports in the space between the skins and the sheet corrugated zigzag filler for local support of the flat side faces and the vertices of the sheet corrugated zigzag filler in a multilayer panel along the median plane on both sides of the panel, which leads to increased stability.

Whereas in a multilayer panel without creating an additional reinforcing filler, which serves as an intermediate additional support for local support of flat side faces, the loss of stability occurs with the appearance of a single wave, which significantly reduces critical stresses (Fig. 8). Strength characteristics increase with increasing critical force P _cr and critical stresses of stability loss σ _cr .

To clarify the technical nature, consider the drawings:

figure 1 - shows a General view of the panel with sheet corrugated zigzag filler;

figure 2 is a flat blank of aggregate;

figure 3 is a view of a multilayer panel without filling the hollow space;

figure 4 - the filling of the auxiliary supporting layer of a liquid material, for example paraffin h _p = N / 3;

figure 5 - execution of the filling of an additional reinforcing filler in the form of foam on top of the auxiliary support layer, such as paraffin;

6 - the creation of supports for local support with additional reinforcing aggregate (foam) along the median plane on both sides of the panel h _sp = N / 2, where:

1 - lower and upper skin; 2 - sheet corrugated zigzag filler; 3 - zigzag lines of protrusions of the corrugation; 4 - zigzag lines of depressions; 5 - additional reinforcing internal filler in the form of a supporting element, a foam substrate; 6 - auxiliary support layer of paraffin, 7 - flat side faces. Designations: Н - panel height from sheathing to sheathing, h _p = H / 3 - paraffin fill level, h _sp = H / 2 - mid-plane level;

7 is a form of loss of stability of the face with local support;

Fig is a form of loss of stability of the face without local support.

Fig.9 is a graph 1, confirming the increased stability and strength characteristics of the elements of the sheet corrugated zigzag filler when applying loads to these samples with local support in the form of foam and without it.

An embodiment of the invention:

The multilayer panel contains lining 1 (upper and lower) and corrugated sheet zigzag aggregate 2 in the form of alternating protrusions and depressions, which is obtained from a flexible sheet stock along lines 3, 4. The planes passing through lines 3 and 4 form flat side faces, traces of mutual intersection which are sawtooth and zigzag lines of leaf aggregate. On lines 3 and 4, a sheet of corrugated zigzag filler is connected to the casing 1. An additional reinforcing filler 5, consisting of foam, is introduced into the formed hollow space between the casing and the sheet corrugated zigzag filler, and which is made in the form of a supporting element, a substrate that is located on both sides the middle plane of the panel at half its height for local support with the possibility of rigid fixation of the flat side faces and the vertices of the sheet corrugated zigzag aggregate. First, on both sides of the panel, an auxiliary layer is created from a liquid material (for example, paraffin), for this, paraffin is poured and in a liquid state into the troughs of the sheet corrugated zigzag filler at the level h _p = H / 3, (where H is the panel height from sheathing to casing, h _n - paraffin fill level), which cures at normal temperature. After curing of paraffin, an additional reinforcing filler is applied on top of it in the form of a foam in a liquid state, which cures at normal ambient temperature (20-25 ° C), to the level h _sp = H / 2, (where H is the height of the panel from the skin to the skin , h _sp is the level of the median plane), so that the additional reinforcing filler is located exactly at the level of the median plane on both sides of the panel, the thickness of the additional reinforcing filler depends on the height of the panel, the thickness of the sheet corrugated zigzag about the filler, but should be calculated taking into account the specified weighted specific strength of the panel, but not more than h _extra = H / 2, (where H is the height of the panel from the casing to the casing, h _extra is the height of the additional reinforcing filler consisting of foam). After the foam has completely cured, the paraffin layer is removed, the panel is placed in an oven and a paraffin layer is obtained in a liquid state at a temperature of 80-90 ° C, and then removed naturally, while the adhesion properties of an additional reinforcing filler with corrugated sheet zigzag are enhanced with increasing temperature placeholder. Thus, at the level of the median plane of the multilayer panel, there remains only an additional reinforcing filler, consisting of foam, providing a given specific gravity compressive strength by increasing the stability of the sheet corrugated zigzag filler with rigid fixation of the flat side faces and the vertices of the sheet corrugated zigzag filler.

An example of a specific implementation:

To confirm the technical result in the claimed technical solution: 3 samples of multilayer panels were manufactured and tested (panel thickness 30 mm, width, length - 150 mm). Sheaths are made of fiberglass 2 mm thick, sheet corrugated zigzag filler is made of Nomex ^® polymer paper and folded so that its thickness in the compressed state is H = 30 mm. An additional reinforcing filler is Sicomin's low-density foam; the auxiliary supporting layer is solid P-2 petroleum solid paraffin (melting point not lower than 58 ° C).

Sample No. 1 - consists of skins and a sheet of corrugated zigzag filler located between them, connected to these skins using composite adhesive material, and an additional reinforcing filler is introduced into the formed hollow space between the skins and the sheet corrugated zigzag filler (full filling of the hollow spaces on both sides throughout the height and volume;

Sample No. 2 - consists of skins and a sheet of corrugated zigzag filler located between them, connected to these skins using composite adhesive material, and in the formed hollow space at the level of the median plane (H / 2 = 15 mm) create local support for flat side faces and the vertices of the sheet corrugated zigzag filler on both sides of the panel formed from an additional reinforcing filler in the form of foam with a thickness of 10 mm (Fig.6).

Sample No. 3 consists of skins and a sheet of corrugated zigzag filler located between them, connected to these skins using composite adhesive material without filling the hollow space (Fig. 3).

The samples were tested for compression and the following data were obtained: maximum compression load: Sample No. 1 - 76 kN, sample No. 2 - 21 kN, sample No. 3 - 0.20 kN. Compared to sample No. 3 (in which the hollow space is not filled with anything and there is no local support for the flat side faces and vertices of the corrugated sheet of filler), sample No. 2 (in which the hollow space is partially filled in the form of an additional reinforcing filler at the mid-plane level on both the sides of the panel, which rigidly fixes the flat side faces and the vertices of the sheet corrugated zigzag filler) withstood a load 100 times greater, which can be seen from graph 1 (Fig. 9).

, (где σ_кр - критические напряжения, w - вес).Thus, we can draw a preliminary conclusion that the use of local support for flat lateral faces and vertices of a sheet of corrugated zigzag filler increases the stability of elements of a sheet of corrugated zigzag filler and the strength characteristics of a multilayer panel at a given weight specific strength $$\frac{{{\displaystyle \sigma }}_{\mathrm{to}R}}{w}$$

, (where σ _cr - critical stress, w - weight).

Technical appraisal and economic advantages of the claimed invention in comparison with known analogues

, (где σ_кр - критические напряжения, w - вес), предлагается производить локальную поддержку плоских боковых граней листового гофрированного зигзагообразного заполнителя, а именно - по срединной плоскости: заполнять дополнительный усиливающий элемент, состоящий из пены в полое пространство между обшивками и листовым гофрированным зигзагообразным заполнителем по срединной плоскости панели (фиг.6). Таким образом, вес конструкции существенно не увеличится, по сравнению с прототипом, но достигают увеличение прочностных характеристик на сжатие за счет повышения устойчивости плоских боковых граней и вершин листового гофрированного зигзагообразного заполнителя, и панели, в целом.When compared with one of the known analogues, the introduction of an additional reinforcing filler, consisting of foam, in the form of a supporting element, a substrate of flat side faces and vertices of a sheet of corrugated zigzag filler in the panel, which can significantly increase the stability of the panel as a whole. In order to maintain a given specific gravity $$\frac{{{\displaystyle \sigma }}_{\mathrm{to}R}}{w}$$

, (where σ _cr are critical stresses, w is weight), it is proposed to provide local support for the flat side faces of a sheet of corrugated zigzag filler, namely, along the median plane: to fill an additional reinforcing element consisting of foam into the hollow space between the skins and sheet corrugated zigzag placeholder on the median plane of the panel (Fig.6). Thus, the weight of the structure does not significantly increase, compared with the prototype, but they achieve an increase in compressive strength by increasing the stability of the flat side faces and vertices of the corrugated sheet zigzag filler, and the panel as a whole.

Claims (2)

1. A multilayer panel containing sheathing, connected by means of composite adhesive material with a sheet of corrugated zigzag filler placed between them with alternating protrusions and depressions, the flat side faces of which are interconnected by zigzag lines, characterized in that it is provided with a supporting element in the form of an additional reinforcing hardened foam filler inserted into the space between the skin and the corrugated sheet zigzag filler and located about both sides of the median plane of the panel passing through half its height. 2. A method of manufacturing a multilayer panel, comprising connecting the skin using composite adhesive material and placing between them a sheet of corrugated zigzag filler with alternating protrusions and depressions, forming flat side faces, characterized in that on both sides of the panel at the level of one third of its height in the depressions a sheet of corrugated zigzag filler is poured with liquid paraffin, which forms an auxiliary layer after hardening, on which an additional force is applied Liquid filler from the foam in liquid state on both sides of the median plane of the panel, passing through half its height, cures the foam to form a supporting element that serves as an intermediate additional support for local support of the flat side faces and vertices of the corrugated sheet of zigzag filler, after which the panel is heated to 80-90 ° C, receive paraffin in a liquid state, which is then removed.

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