RU2267404C2 - Method of manufacture of a pleated filler out of composite materials for production of sandwich panels - Google Patents

Abstract

FIELD: construction industry; methods of manufacture of a pleated filler out of composite materials for production of sandwich panels.

SUBSTANCE: the invention is pertaining to production of the channeled constructions with the pleated filler made out of composite materials. The method includes a laying of a planar sheet of a reinforcing material billet, its impregnation with a binding substance, production of a prepreg, curing of the binding substance in the process of the hot pressing with production of a planar billet - semi-finished product in the form of a combination of the relatively rigid sections, having the shape of sides of the pleated filler and separated from each other by some space. After that follows a form-shaping of the billet- semi-finished product by bending with production of a relief form of the pleated filler with the necessary geometric parameters, and the final curing of the whole applied binding substance. The reinforcing material is impregnated over the whole surface of the billet. A heat feeding for the binding substance heat setting in the produced prepreg conduct only within the limits of the above indicated sections. Along the bands of the prepreg between these sections create conditions retarding the process of the curing. The given engineering solution raises efficiency of the process.

EFFECT: the invention ensures an increased efficiency of the process.

2 cl, 2 dwg

Description

Technical field

The invention relates to the manufacturing technology of corrugated structures from layered composite materials.

State of the art

There is a known method of manufacturing products from a layered composite material, which consists in laying a fabric impregnated with a binder sheet (prepreg) on a molding mandrel, sealing with a vacuum bag and molding the product under atmospheric pressure (Krysin V.N., Krysin M.V. Technological processes of molding , winding and gluing structures. - M.: Mechanical Engineering, 1989. - 240 p., s.118-125, ISBN 5-217-00533-5).

The disadvantage of this method is the low productivity associated with the high complexity of laying the prepreg sheet in the form with a complex relief, the impossibility of its practical implementation with a relatively dense relief of the folded structure of the filler, as well as the high cost of the relief tooling.

A known method of molding corrugated aggregate using transformable mandrels. The method consists in the fact that the composite material in the form of a prepreg is laid on the flat surface of the snap, which is then transformed into a folded structure with the required geometric parameters of the relief, after which molding is performed. To do this, in order to obtain high technical characteristics, this device with the product is placed in an autoclave, where the necessary technological conditions are implemented (pressure up to 0.6-0.8 MPa and temperature up to 200 ° C) (V.I. Khaliulin. Technological schemes for manufacturing multilayer constructions .-- Kazan: Publishing House of Kazan State Technical University, 1999 .-- 168 p., pp. 149-155, ISBN 5-7579-0295-7).

The disadvantage of this method is the need to expose high temperature and pressure forming equipment, which significantly reduces its technical resource.

A known method of manufacturing products from a layered composite material, which consists in the fact that the first step is the discrete deposition of a binder on a pre-marked flat sheet of fabric in areas corresponding to the side faces of the folded type filler to obtain strips of non-impregnated fabric along the connection lines of these faces. At the second stage, the fabric so impregnated in a flat state is placed between the heated press plates, after which the binder is cured at a certain temperature and pressure. At the third stage, the scan is removed from a flat state by folding by bending along the non-saturated strips of fabric. To impart rigidity to the aggregate, the non-impregnated strips are impregnated with a binder followed by its curing (RF Patent No. 2057647 C1 IPC ₆ V 29 D 9/00. A method of manufacturing an aggregate from composite material. Bull. No. 10, 04/10/96). This method is adopted as a prototype.

The disadvantages of this method are the lack of technological feasibility of its first stage when using thin fabrics. The thickness of the fabrics used in the manufacture of composite products is 0.1-0.2 mm. To obtain high accuracy of the geometric parameters of the relief, the width of the strips of the non-impregnated fabric along the connection lines of the side faces of the filler should be 0.2-0.4 mm.

Since the material of the reinforcing base of the prepreg (glass-, carbon-, organo-fabric) has a capillary-porous structure, when a binder is applied to the areas corresponding to the lateral faces of the folded structure, it can penetrate into the zones of the fold lines. In this case, at the next stage (molding stage), when the heat is supplied to the billet, curing of the binder will also occur in these zones, which will deprive the billet of mobility on the bend lines and complicate the process of transforming a flat billet into a three-dimensional structure.

Since the fabric impregnated with the binder is a non-rigid body, when it is laid on a press plate for further molding, it is necessary to ensure high accuracy of the actual dimensions of the faces and bending lines to the parameters of the ideal sweep of the filler and, accordingly, to the parameters of the filler in a raised state. This condition is difficult to fulfill and requires special equipment and additional labor costs. Skewing of the fabric in any direction with a pattern of faces impregnated on it, impregnated with a binder composition and non-impregnated fold lines, leads to a distortion of the geometric parameters of the structure of the folded filler.

SUMMARY OF THE INVENTION

The objective of the invention is to provide the possibility of using the finished prepreg as a prefabricated semi-finished product and to improve the conditions for folding a flat preform into a three-dimensional embossed structure.

The technical result achieved by using this invention is to increase the productivity of the process of manufacturing aggregate from composite material by using the finished prepreg as its preform and thereby reduce the number of operations, as well as improving the quality of manufacturing by increasing the accuracy of shaping.

The specified technical result is achieved by the fact that in the known method of manufacturing folded aggregate for composites from composite materials, comprising laying a preform of reinforcing material, impregnating it with a binder to obtain a prepreg, curing the binder in the hot pressing process to obtain a flat semi-finished preform in the form of a combination of relatively rigid sections having the shape of filler faces and separated from one another by a certain distance, subsequent deformation of the semi-finished workpiece kata with obtaining a relief of the filler with the required geometric parameters and the final curing of the entire applied binder, while the reinforcing material is impregnated with a binder over the entire surface of the workpiece, heat is supplied to cure the binder in the obtained prepreg only within the mentioned sections, and create prepreg bands between these sections conditions slowing down the curing process. In addition, the width of the strips between the relatively rigid sections provide equal to at least two values of the bending radius of the workpiece material in these sections.

The analysis of the prior art carried out by the applicant made it possible to establish that there are no analogs characterized by sets of features identical to all the features of the claimed technical solution. Therefore, the claimed technical solution meets the condition of patentability "novelty."

The search results for known solutions in the art in order to identify features that match the distinctive features of the prototype of the features of the claimed technical solution have shown that they do not follow explicitly from the prior art. From the prior art determined by the applicant, the influence of the transformations provided for by the essential features of the claimed technical solution on the achievement of the specified technical result has not been revealed. Therefore, the claimed technical solution meets the condition of patentability "inventive step".

Brief Description of the Drawings

The invention is illustrated in figures 1 and 2, where figure 1 shows a folded filler type "zigzag corrugation"; figure 2 - its scan.

In figures 1 and 2, the numbers indicate the following positions: 1 - sections of the prepreg, cured in the process of hot pressing; 2 - areas cured after the formation of the aggregate.

The best embodiment of the invention

The method is implemented as follows.

At the first stage, a flat sheet of prepreg, which is a reinforcing fabric pre-impregnated with a binder and preserved in such a state (glass, coal, organo-fabric), is laid on a flat surface of heated press plates and the workpiece is hot pressed. In this case, heat supply is carried out only in areas 1 having the shape of filler faces, but less in area, and during the time minimally necessary to ensure the degree of cure that meets the conditions for subsequent shaping of the filler flexible. The result is a transformable structure consisting of relatively rigid elements (faces of the future aggregate) and elastic sections of the prepreg in the zones between them.

At the next stage, flexible folding of the semi-finished preform in sections 2 carry out shaping of the folded structure to obtain the required geometric parameters (figure 1).

To impart rigidity to the structure in the plane of the aggregate, the entire cured binder is finally cured and thus the product is stabilized. This operation may or may not be present or be combined with the operation of assembling the filler with the skin, for example, using film glue, to obtain a three-layer panel. In the latter case, the flexibility of the aggregate material taking place at this stage in the area of the ribs of the folded structure, i.e. in the areas of connection with casing, it allows to improve the quality of the connection due to the unconditional provision of contact along their entire length. If necessary, when assembling with casing, curved sections on the bends can be deformed to form flat areas, which can increase the strength of the connection.

The proposed method allows the use of a ready-made prepreg, manufactured on high-performance equipment by industrial methods with high quality impregnation, which significantly reduces labor costs for the production of aggregate, improves the quality of the product and the culture of its production.

Industrial applicability

The invention can be used in the manufacture of multilayer panels used in the manufacture of aircraft, shipbuilding and in building structures.

Claims (2)

1. A method of manufacturing a folded aggregate for composites of composite layers comprising composing a flat sheet of a blank of a reinforcing material, impregnating it with a binder to produce a prepreg, curing the binder during hot pressing to obtain a flat semi-finished blank in the form of a set of relatively rigid sections shaped as filler faces and separated from one another by a certain distance, the subsequent shaping of the semi-finished preform flexible with obtaining a relief of the filler with t the required geometric parameters and the final curing of the entire applied binder, characterized in that the reinforcing material is impregnated with a binder over the entire surface of the workpiece, heat supply for curing the binder in the obtained prepreg is carried out only within the mentioned sections, and the conditions slowing down the process are created along the prepreg bands between these sections curing. 2. The method according to claim 1, characterized in that the width of the strips between relatively hard sections is equal to at least two values of the bending radius of the workpiece material in these sections.

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