RU2262551C2 - Method of manufacture of hollow articles of intricate form from composite materials with metal coat on internal surface - Google Patents

Abstract

FIELD: radio industry and aerospace engineering.

SUBSTANCE: proposed method includes application of metal coat on mandrel made from material whose melting point is above hardening temperature of binder but is below heat-resistance temperature of composite material. Then, layers of reinforcing material impregnated with thermoactive binder are wound on dusted surface of mandrel, binder is formed by hardening and mandrel is molten out of interior of article.

EFFECT: facilitated procedure of manufacture; low cost; possibility of obtaining smooth coat on inner surfaces of articles.

3 cl, 1 dwg, 1 ex

Description

The present invention relates to the field of radio industry and aerospace engineering, in particular to the production of tubular elements of complex shape with a metallized coating of the inner surface, and can be used in the development and manufacture of layered products from composite materials, for example, waveguides.

A known method of coating the inner surface of the pipe, which consists in the fact that inside the pipe installed in a vacuum chamber, the wire is pulled and heated by passing an electric current through it to an evaporation temperature, as a result of which the metal from which it consists is deposited the specified wire [1].

Significant disadvantages of this method are the low adhesion of the sprayed metal and the fact that this method does not guarantee the exclusion of deformation and welding of the wire to the inner surface of the pipe. Product dimensions are limited by the dimensions of the vacuum chamber, the installation for coating.

In addition, in the manufacture of products of complex configuration that does not allow to stretch a metal wire inside the product without touching its walls, the application of this method is impossible.

Also, this method involves two stages of manufacture: pipe forming and subsequent spraying on its inner coating surface, which increases the duration of the process and requires additional special equipment (a vacuum chamber, an electrical installation with electrodes), which significantly increases the cost of the product.

Closest to the claimed method in technical essence is a method for manufacturing hollow layered products of various configurations by winding, which consists in the fact that a prepreg is wound on a mandrel made of fusible material, heated, curing, and the mandrel is melted to remove it from the product [ 2].

This method allows the manufacture of products of complex geometric shapes and to simplify the manufacturing technology of products by simplifying the operation of removing the product from the mandrel, to exclude the use of special equipment when removing the product, which reduces the manufacturing time of hollow products from laminated plastic and, therefore, reduces production costs.

However, this method does not provide for the manufacture of tubular elements with a metal coating of the inner surface.

The objective of the invention is the manufacture of hollow products of complex geometric shapes from CM with a metal coating of the inner surface, for example, waveguides, increasing the adhesive strength of the coating, simplifying the manufacturing process and controlling the quality of the product, reducing the cost of the product.

This goal is achieved by the fact that in the method of manufacturing hollow articles from composite materials, which includes assembling the package by winding layers of a reinforcing material impregnated with a thermosetting binder on the mandrel, curing the binder and metallization, metallization is carried out by spraying in an air environment by an electric arc method on a low-melting metal mandrel with subsequent winding of the package on a metallized surface, curing the binder and smelting the mandrel from the cavity of the product.

In the manufacture of products having a very complex shape of the inner surface, which makes it difficult to uniformly apply the coating by electric arc spraying due to existing undercuts and complex transitions of surfaces, the coating on the mandrel is made by the method of chemical galvanic metallization.

This method, although it has a greater complexity, cost and lower adhesive strength of the coating compared to the above, allows you to get a uniform metallized coating on the inner surfaces of products of any complexity of shape and exceeds these indicators of known methods.

The mandrel is made of a material having a melting point higher than the curing temperature of the binder, but lower than the temperature resistance of the composite material.

New significant features of the proposed method is the principle of manufacturing hollow products from KM of complex geometric shape with a metal coating of the inner surface in one cycle.

The proof of the possibility of obtaining a positive effect is the experimental production of prototypes of products from composite materials with a metallized coating of the inner surface and comparing them with the prototype.

Description of the manufacturing technology of the sample, the meaning of the individual parameters will be given below. Here we only note that the manufacture of samples by the claimed method in comparison with the prototype is distinguished by technological simplicity, production operations are more cost-effective and can be automated for serial and mass production. In addition, this method allows you to get samples of any size and configuration with increased adhesive strength of the coating.

Example. The manufacture of carbon fiber products of the type "waveguide curvilinear circular shape with a metal coating of the inner surface" of the claimed method.

The assembly of the package is carried out by winding the binder-impregnated reinforcing material onto a metallized layer deposited on a pre-polished mandrel.

As a reinforcing material used carbon tape LU-P / 0.2 GOST 28006-88, fiberglass E2-62 GOST 19907-83 (1st layer on a metallized coating).

The binder used is 5-211-B, the volume fraction of which in the prepreg is (36 ÷ 42)%.

The manufacture of the product is carried out in the following sequence (the manufacturing steps are presented in the drawing).

On a pre-polished surface of the mandrel (1), made of low-melting alloy MCP 137, with a melting point of 137 ° C, a metal layer (2) with a thickness of 0.08 ÷ 0.09 mm, for example aluminum, is uniformly applied. The metal layers are deposited using an ARC SPRAY 8830 electric arc spraying machine (3) in air.

Next, on the metallized surface of the mandrel, a packet (4) is assembled, consisting of fabric prepreg E2-62 (first layer) and carbon prepreg layers, pulled together through a certain number of fiberglass layers, assembled according to the reinforcement scheme: 5 carbon fiber layers 0 °, fiberglass layer 90 °. After assembly, the bag is pulled together by a glass fiber under a certain tension, thereby creating pressure during molding.

Next, the product is molded in a heating cabinet (polymerization furnace) at a temperature of (+ 125 ± 5) ° С for 4 hours. Then the product is heated to 137 ° C, without removing from the oven (polymerization furnace), to melt the mandrel from the product. After which the product is cooled.

Made by the claimed method, the product is characterized by the following indicators:

- adhesive strength of the coating is not less than 90 MPa;

- the geometric shape of the inner surface of the product completely repeats the shape of the mandrel.

The product made by the claimed method does not require additional machining of the metallized surface, since it is an impression from the polished surface of the mandrel. The adhesive strength of the coating is much higher than the known methods, since the metal deposited on the mandrel has a uniformly developed rough surface structure facing the layers of a binder-impregnated reinforcing material laid on the sprayed surface of the mandrel.

The method proposed in the application is more economical in comparison with the known one, since one of the most complex operations — metallization of the internal surface of an item with a complex geometric shape — is significantly simplified and does not require the use of special expensive equipment, and the manufacture of the product (molding, coating and mandrel removal) is performed one cycle. The mandrel material smelted from the cavity of the product is used for casting new mandrels.

The application of the proposed method allows to control the quality of the coating (continuity, thickness, lack of inclusions, etc.) and identify defects at the initial stage of manufacturing products - the stage of coating the mandrel, in contrast to the known method, where quality control of the coating is possible only on the finished product , and if the coating does not meet the requirements for it, the entire product will be rejected. In addition, the control of coating the inner surface of a product of complex shape is quite complicated and requires the use of special equipment, equipment and tools, in contrast to the proposed method of manufacturing products, where the control process is greatly simplified, because controlled coverage is easily accessible. These advantages are especially noticeable in the manufacture of products with increased coating requirements, such as waveguides.

The cost of products manufactured by this method is lower than known, and the dimensions and configuration of products during spraying and assembly are determined only by the dimensions and configuration of the mandrel, and compared to known methods, the manufacturing technology of such products is simpler.

Sources of information

1. Patent JP 5842267, C 23 C 13/02 09/19/1983 - analogue.

2. Kalinchev V.A., Makarov M.S. Wound fiberglass. - M .: Chemistry, 1986, pp. 178-187 - prototype.

3. Determining the conformity of technical solutions to the criterion of "significant differences" - Inventions, 1984, No. 4.

4. Patent Law of the Russian Federation, 1992, No. 3517-1.

Claims (3)

1. A method of manufacturing hollow articles of complex shape from composite materials with a metallized inner surface, comprising assembling a bag by winding layers of a reinforcing material impregnated with a thermosetting binder, on a mandrel made of a material having a melting point above the curing temperature of the binder, but below the temperature resistance of the composite material , metallization, the formation of a curing binder and removal of the mandrel, characterized in that the metallization of the inner surface of the ed Helium is produced by applying a metal coating to the mandrel, followed by winding the bag onto the sprayed surface, curing the binder, and melting the mandrel from the inner cavity of the product. 2. The method according to claim 1, characterized in that a metal layer is applied to the surface of the fusible mandrel by electric arc spraying in air. 3. The method according to claim 1, characterized in that a metal layer is applied to the surface of the fusible mandrel by the method of chemical-galvanic metallization.