RU2504477C1 - Method of making cellular sound-absorbing panel - Google Patents

Abstract

FIELD: process engineering.SUBSTANCE: invention relates to sandwiched sound-absorbing structures to be used in aircraft engineering, ship building, automotive industry, particularly, to production of cellular sound-absorbing panel. Proposed method comprises making the inner skin impregnated with polymer binder and filler composed by at least two corrugated inner and outer plates. Outer skin outer plate has crimp peaks directed in one direction. Inner plate is made with symmetric crimps. Grooves are made to depth equal to section height minus material thickness and at distance defined subject to preset curvature radius, tolerable strain and material elastic modulus. Plates are assembly in one plane over the ledges and sockets at crimp peak to make the cells. Filler plates and lower skin are attached by compaction to make rigid glue bond. Plates and skin are formed in single polymerisation cycle. Crimp side walls feature equal angle inclination to the base. Outer plate is formed with crimp pitch of 1.5-2 of plate profile. Glue is applied on outer plate inner surfaces and lower skin, then, skin and plates are assemble and glued together against the stop.EFFECT: accelerated process, expanded applications, sufficient flexibility.6 cl, 5 dwg

Description

The invention relates to the manufacture of multilayer sound-absorbing structures with cellular aggregate, which can be used in aircraft construction, shipbuilding, automotive and other industries.

A known method of manufacturing a relief aggregate (RF Patent No. 2307032 V29C 53/24) by plastic deformation of a thermoplastic prepreg, including sequential molding of the primary sawtooth corrugation of a given structure with contact strips and a given bending angle. The formation of the primary sawtooth corrugation is carried out on cold formers in the longitudinal direction with a drawing speed of 0.5-0.8 m / min, the cellular relief is formed by deforming the corrugation of a given structure in the transverse direction with the formation of flat contact spots at the vertices of the cellular relief, and before each By forming, the prepreg is heated to a temperature of 20-30 ° C below the melting temperature of the thermoplastic. In addition, the diameter of the flat contact spot at the top of the cellular relief is equal to the width of the corrugation contact strip of a given structure, and the prepreg uses a thermoplastic of an amorphous semicrystalline or crystalline structure or with a melting temperature below the temperature of polymer degradation. Additionally, welding strips of a given structure to the desired width.

A disadvantage of the known method of manufacturing embossed aggregate is the need to manufacture the casing of the upper and lower, and in the manufacture of a multilayer sound-absorbing structure (ZPK), the additional production of interlayer gaskets, which significantly increases the weight of the ZPK design. The cells are obtained by stepwise sequential molding of the primary sawtooth corrugation, the corrugation of a given structure with contact strips and the formation of a cellular relief with heating at each stage 20-30 ° C below the melting temperature, with a glass transition temperature below the temperature of destruction, which negatively affects the heat resistance of the obtained cellular panels . The manufacturing process of embossed aggregate with intermediate manufacturing steps lengthens the process cycle. The percentage of coverage of the area of the cellular aggregate with cells reaches 60-70%, which reduces the efficiency of sound absorption. In addition, the proposed method of manufacturing a relief aggregate, it is possible to produce ZPK with cells of the same shape with the same operational capabilities and, accordingly, with a narrow scope.

A layered product with corrugated filler made of fibrous plastic and a method for its manufacture are known (RF Patent No. 2144469, IPC В32В 3/12). The invention relates to the manufacture of multilayer products from thermosetting plastic with fibrous filler in the form of a rectangular corrugation obtained by pressing, and can be used in aircraft and shipbuilding in the manufacture of interior panels, partitions, etc. The layered product contains parallel upper and lower sheathing and a filler made of a fibrous filler impregnated with a polymer binder. The filler is made in the form of a series of double corrugations of rectangular shape. The corrugations are glued inside each row along the vertical tangent walls of the combined corrugations. The corrugations are rigidly connected to the skin along the planes of their tops with an adhesive joint.

A method of manufacturing a layered product includes the manufacture of upper and lower skin and corrugated aggregate. Then the corrugated aggregate is attached to the casing by pressing to form an adhesive joint along the planes of the corrugation tops. The aggregate is formed by pressing in stages. First, two open half-corrugations with triangular corrugations of the same height and thickness and with two successively alternating corrugation steps are made. Then each half-corrugation is pressed in a mold with grooves for corrugations of a rectangular shape with a height of a corrugation equal to the length of a rib of a triangular corrugation, with two successively alternating corrugation steps, respectively equal in size to the corrugation steps of an open half-corrugation. Pressing is carried out simultaneously with the upper or lower casing until the formation of the upper or lower half-panel, respectively. After that, the protrusions of the corrugations of the upper half-panel, offset from the corrugations of the lower half-panel at any of the two corrugation steps, are combined in the same plane with the corresponding troughs of the corrugations of the lower half-panel until they stop, forming a rigid adhesive joint along the contact planes of the vertical walls of the combined corrugations. For this, the difference of two alternating values of the corrugation steps is made equal to twice the thickness of the corrugation wall.

Common essential features for the presented analogue and the claimed technical solution are:

- manufacture of the lower skin;

- manufacture of corrugated aggregate made of 2 plates;

- the implementation of the corrugated filler from a filler impregnated with a polymer binder;

- combine to the stop with the formation of a rigid adhesive connection along the touch planes;

- corrugations are rigidly connected to the skin along the planes (developed contact surface of the filler with the skin).

In a known manner, it is possible to manufacture products with a large specific gravity and high specific stiffness (the ratio of the area of the panel providing the specified stiffness to its mass). Already at the first intermediate stages, half-panels with a sufficiently high stiffness coefficient are formed.

The disadvantages of the known layered products are the high complexity of manufacturing and material consumption, the duration of the technological cycle, due to the phased production of panel elements, the need to manufacture external and internal cladding. A layered product obtained in a known manner has a high manufacturing cost, limited technological capabilities due to the rigidity of the structure — such a design cannot be used for facing curved surfaces of complex shape. In addition, the method provides for the manufacture of panels, primarily intended for use in aircraft and shipbuilding in the manufacture of interior panels, partitions, but does not solve the problem of facilitating the design and sound absorption, which reduces the operational properties of the panels.

A technical solution is known for a sound-absorbing structure with honeycomb according to RF patent No. 2432259, IPC В32В 3/28, including upper and lower casing, between which honeycomb is placed, containing mutually intersecting corrugated profiles, interconnected by grooves made in the profile with symmetrical corrugations. A profile with symmetrical corrugations is made with a developed contact surface at the vertices of the corrugations. The grooves are made to a depth equal to the height of the profile minus the thickness of the material, and at a distance determined from the conditions of a given radius of curvature, allowable stress and elastic modulus of the material. The corrugation vertices of the second profile are directed in one direction, and its base is simultaneously the outer skin.

The design of the sound-absorbing panel involves a manufacturing method based on sequential operations. The manufacture of internal and external sheathing and filler from a polymer composite material, the filler is molded from 2 corrugated profiles (plates), one of which is molded with corrugated vertices pointing in one direction, the other is molded with symmetrical trapezoidal corrugations, across which from one side perform grooves. The combination of corrugated plates is carried out in the same plane along the protrusions and corresponding grooves at the tops of the corrugations with the formation of cells. The attachment of the aggregate plates and the lower skin is made by compression under load. The outer profile of the plate is formed by manually laying glass or carbon fabric on the corrugated plate of the trapezoidal profile, using additional devices in the form of embedded plates. Glass or carbon fabric is sequentially threaded into each groove of a symmetrical trapezoidal plate, secured by a embedded plate, after which the load is balanced by each embedded plate and pressed under load. The resulting aggregate is connected to the inner lining along the developed contact surfaces of the inner plate by gluing and subsequent drying.

The method has a significant drawback, namely, that the process of producing aggregate plates proceeds in stages with polymerization on each, first the first corrugated plate is made, and then using it as a base or matrix, a plate with corrugation vertices directed in one direction is obtained. The operation of manufacturing the corrugations of the outer plate is performed manually by using additional technological devices that make it possible to hold glass or carbon fabric impregnated with a polymeric binder in each groove of the corrugated plate, which complicates and lengthens the entire technological process of forming and assembling the ZPK.

The objective of the invention is to reduce the complexity of manufacturing and materials, increasing productivity, expanding the scope.

Achieved technical result:

- reduction of the technological cycle due to the manufacture of all corrugated aggregate and casing panels simultaneously for one polymerization cycle;

- obtaining multilayer sound-absorbing panels with various designs, achievable technical characteristics and operational properties, allowing to expand the scope (in aircraft and shipbuilding in the manufacture of interior panels, partitions, etc.).

- eliminating the need for the manufacture of outer skin and inner walls in the manufacture of a multilayer aggregate, and due to this, a decrease in the specific gravity of the aggregate and the preservation of design flexibility.

- the method allows you to build the technological process of manufacturing elements of the ZPK in an automated production line.

The technical result is achieved due to the fact that in the method of manufacturing a cellular sound-absorbing panel, including the manufacture of internal lining impregnated with a polymer binder and an aggregate formed from at least 2 corrugated plates, one of them, which is external - external lining, is formed with corrugated vertices directed in one direction, the other - the inner one is formed with symmetrical corrugations, on one side transverse of the corrugations grooves are made to a depth equal to the profile height minus the plate thickness at a distance of removable from the conditions of a given radius of curvature, allowable stress and elastic modulus of the material, assembling the plates in one plane along the protrusions and corresponding grooves at the vertices of the corrugations to form cells, attaching the aggregate plates and the lower skin by pressing to form a rigid adhesive joint, the operation of forming the plates and sheathing is carried out simultaneously in one polymerization cycle, while the side walls of the corrugations are made with the same angle of inclination to the base, the outer plate is formed with 1.5-2 agom corrugation height of its profile, the adhesive composition is applied to the inner surface of the outer plate and the lower shell, and then assemble the trim panel and gluing of plates until it stops.

The manufacture of multilayer panels produce:

- assembly of two basic fillers - for a two-layer panel;

- placing between them a package of plates located on top of each other with integral symmetrical corrugations - for a multilayer panel, while the assembled package of plates is assembled in a different order and different relative positions, namely:

- placing the corrugations of the plates in one direction with the formation of through channels;

- with rotation relative to each other in the same plane by 90 °, forming through channels in a mutually perpendicular direction;

- combined, placing the corrugations in one direction and mutually perpendicular.

The inventive combination and the relationship of essential features is new, because when using them, a new technical result described above is achieved that is not inherent in the identified analogues of the structures and methods for manufacturing sound-absorbing structures.

Fig. 1 shows the assembly diagram of the aggregate, in Fig. 2 - a single-layer panel, in Fig. 3 - a two-layer panel, in Fig. 4 - a three-layer panel, in Fig. 5 - a four-layer panel.

The method is as follows.

At least two types of corrugated plates participate in the technological cycle of panel aggregate manufacturing: plate 1 with corrugated vertices directed in one direction and plate 2 with symmetrical corrugations, which are the basis for creating a multilayer structure.

Taking into account the tasks set, for example, the given frequencies of sound waves, bending radius, etc., the sizes and design parameters of the cells are selected, based on which, from the prepreg, at the same time for one polymerization cycle, the plate is formed 1- outer, plate 2 - internal ( Fig. 1) and casing 3 (Fig. 2). Plate 2 is formed with symmetrical trapezoidal corrugations, plate 1 is unidirectional corrugations with a step of corrugations of 1.5-2 height of its profile, the side walls of corrugations of both plates 1 and 2 are made with the same angle of inclination a to the base to ensure that plates 1 and 2 are aligned without gaps. The process of simultaneous molding in one polymerization cycle of plates 1, 2 and casing 3 can be carried out simultaneously, for example, in an autoclave or polymerization furnace at a temperature determined by the properties of the prepreg and the mode of its molding to the polymerization temperature, followed by exposure and cooling. Then, in the plates 2 with symmetrical corrugations, for example, circular knives, grooves 4 are cut across the corrugation vertices to a depth equal to the profile height minus the thickness of the plate 2, at a distance corresponding to the corrugation step of the outer plate 1, the width L of the groove 4 corresponds to the width L of the base of the unidirectional vertices corrugation of the outer plate 1 and is 1.5-2 heights of the corrugations (Fig. 1). After that, glue of cold (for example - K-300-61) or hot (for example - VK3A) curing is applied on the inner surfaces of the outer plate 1 and the lower skin 3 or only on the plate 2 with symmetrical corrugations. Next, the assembly and gluing process of the casing 3 and both plates 1 and 2 is carried out. Assembly is carried out by combining the grooves 4 of the symmetrical corrugations of the plate 2 and the vertices 5 of the unidirectional corrugations of the plate 1 until they stop at multiple local contact areas without gaps. After that, the plates 1, 2 and the casing 3 are pressed under load with the modes in strict accordance with the selected adhesive, forming a rigid adhesive connection with the flexibility of the panel (figure 2). The formation of a plate with unidirectional corrugations with a step amounting to 1.5-2 of the height of its profile, determined by calculation and confirmed experimentally, is necessary and sufficient to give the filler the property of flexibility within the radius of curvature of the surface while maintaining sufficient strength to enable the external function to be performed casing, high cell density 6, which provides a high level of sound absorption. The manufacture of plates 1, 2, and casing 3 simultaneously in one polymerization cycle solves the problem of manufacturing a ZPK with the same physical and mechanical properties that provide high performance characteristics, in addition, the method allows you to build the manufacturing process of manufacturing ZPK elements in an automated production line. The same angle of inclination to the base of the side walls of the corrugations of both plates allows for high-quality assembly and gluing of the plates without gaps. By connecting the outer plate 1 and the plate 2 in the same plane along the protrusions 5 and the corresponding grooves 4, a cellular base aggregate is obtained (Fig. 1). For the manufacture of a two-layer sound-absorbing panel (Fig. 3), the assembly is carried out from two basic fillers (Fig. 1), while the filler is oriented so that the flat side of the plates with corrugations directed in one direction is the outer surface of the panel. By orientating the corrugations of the aggregates in one direction, a panel with a high coefficient of strength and sound absorption is obtained, while maintaining the flexibility of the original aggregate. For the manufacture of a multilayer sound-absorbing panel (Fig. 4, 5), a prefabricated package of plates 7 located on top of one another with integral symmetrical corrugations is placed between two base fillers. Depending on the choice of the assembly order of plates 7 with integral corrugations and changing the relative position of the plates 7 of the assembled package, various technical problems are solved, the properties of the panel are changed - mechanical (strength, flexibility, weight), new operational properties (reliability, sound absorption) are given to the filler. So, for example, to obtain a sound-absorbing panel with a lightweight, durable flexible structure while maintaining sound absorption properties, the package of plates 7 is assembled with the corrugations in one direction, forming through channels (Fig. 4).

To obtain a sound-absorbing panel of a rigid structure, a package of plates 7 with integral symmetrical corrugations is assembled by placing them with rotation in the same plane, forming through channels in a mutually perpendicular direction (Fig. 5). Thus, having a prefabricated package of plates with unidirectional corrugations between the base aggregates, a multilayer aggregate of a new design with cells in the outer layers and channels in the inner ones is obtained, while the aggregate acquires various mechanical and operational properties in each particular assembly variant.

The proposed method in comparison with analogues and prototype allows you to: reduce the complexity and material costs of manufacturing a sound-absorbing structure by eliminating the operation of manufacturing the outer skin, and in the manufacture of multilayer aggregate - and the inner skin, which provides a significant reduction in the weight of the structure; reduction of the duration of the technological cycle due to the formation of plates and casing simultaneously for one polymerization cycle; expanding technological capabilities - manufacturing on the basis of two base plates of a multilayer aggregate with various operational properties, which allows you to expand the scope, in addition, the method allows you to build the manufacturing process of manufacturing elements of the ZPC in an automated production line.

Claims (6)

1. A method of manufacturing a honeycomb sound-absorbing panel, including the manufacture of an inner lining impregnated with a polymer binder and an aggregate formed from at least two corrugated plates, one of which is the outer - outer skin is formed with corrugation vertices pointing in one direction, the other - the inner one is formed with symmetrical corrugations, on one side across the corrugations grooves are made to a depth equal to the height of the outer plate profile minus the plate thickness at a distance determined from the conditions of a given dimension the radius of curvature, permissible stress and elastic modulus of the material, the plates are assembled in one plane along the protrusions and corresponding grooves at the vertices of the corrugations with the formation of cells, the filler plates and the lower skin are joined by pressing to form a hard adhesive joint, characterized in that the plates and skin are molded produce simultaneously in one polymerization cycle, while the side walls of the corrugations are performed with the same angle of inclination to the base, the outer plate is formed with a step of corrugations of 1.5-2 you cells of its profile, the adhesive composition is applied to the inner surfaces of the outer plate and the lower skin, then the skin and plates are assembled and glued to the stop. 2. The method according to claim 1, characterized in that for the manufacture of a multilayer panel, two aggregates are assembled. 3. The method according to claim 1, characterized in that for the manufacture of a multilayer panel between the placeholders place a package of plates located one above the other with solid symmetrical corrugations. 4. The method according to claim 3, characterized in that the package of plates is assembled by placing the plates in one direction of the corrugations with the formation of through channels. 5. The method according to claim 3, characterized in that the package of plates is assembled by placing the plates rotated in the same plane, forming through channels in a mutually perpendicular direction. 6. The method according to claim 3, characterized in that the package of plates is assembled by placing the plates in combination - in one direction of the corrugations and mutually perpendicular.

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