RU2232681C2 - Method of manufacture of tubular members from composite materials with metallic coat on inner surface - Google Patents

Abstract

FIELD: radio industry and aerospace engineering; manufacture of waveguides.

SUBSTANCE: proposed method includes metallizing of inner surface by spraying metal on mandrel in air medium by electric arc method; layers of reinforcing material impregnated with thermo-reactive binder are wound on mandrel. Then binder is hardened.

EFFECT: enhanced adhesion strength of coat; facilitated procedure.

3 cl, 1 ex

Description

The present invention relates to the field of radio industry and aerospace engineering, in particular to the production of tubular elements with a metallized coating of the inner surface, and can be used in the design and manufacture of layered products from composite materials, such as 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, 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 of manufacturing pipes from laminated plastic, which consists in the fact that on a cylindrical mandrel made of a material with a high coefficient of thermal expansion and good release properties, a sheet prepreg is wound; heated by curing and at the same time due to the thermal expansion of the mandrel, the increase in the inner diameter of the tube stock is cooled, forming a gap from the outer surface of the mandrel, and then the mandrel is removed / 2 /.

This method allows 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 pipes 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, in addition, it does not allow the manufacture of products from a material on a cold cure binder.

The objective of the invention is the manufacture of tubular elements from CM with a metal coating of the inner surface of large and small dimensions, for example waveguides, increasing the adhesion strength of the coating, simplifying the process and reducing the cost of the product.

This goal is achieved by the fact that in the method of manufacturing tubular elements from composite materials, including assembling the bag 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 medium by an electric arc method on a mandrel pre-treated with anti-adhesive, followed by winding the package on the sprayed surface, curing the binder and removing the product from the mandrel.

To facilitate removal and to prevent damage to the coating of the product when using a binder “cold cure” (curing at normal temperature), the mandrel is made of a material with a high coefficient of linear thermal expansion and an internal cavity for placing liquid nitrogen in it to cool the mandrel and thereby create a gap with the inner pipe surface.

New significant features of the proposed method are the principle of manufacturing a tubular element from KM with a metal coating of the inner surface in one cycle, which includes spraying a metal layer by electric arc method in air on a mandrel coated with a release agent, followed by winding the bag on the sprayed surface and curing the binder.

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 to obtain samples of any size with high adhesive strength of the coating.

Example. The manufacture of carbon fiber products of the type “Fragment of a circular waveguide with a metal coating of the inner surface” of the claimed method.

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

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 ENFB TU 1-596-36-98, the volume fraction of which in the prepreg is (36-42)%.

The manufacture of the product is carried out in the following sequence.

A thin coat of release agent (MODELLACK MCP / TAGA) is applied to the pre-polished surface of the cylindrical mandrel.

A layer of metal with a thickness of 0.08-0.09 mm, for example zinc, is uniformly applied to the surface of the mandrel thus prepared. Metal layers are applied using an ARC SPRAY 8830 electric arc spraying machine in air.

Then, on the metallized surface of the mandrel, a package is assembled, consisting of fabric prepreg E2-62 (first layer) and layers of carbon prepreg, stretched together through a certain number of fiberglass layers, assembled according to the reinforcement scheme: 5 carbon fiber layers 0 °, glass fiber 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 (+ 165 ± 5) ° С for 7 hours.

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 manufacturing accuracy of the inner surface of the waveguide is limited by the manufacturing accuracy of the mandrel; smooth smooth surface of the sample, which is a mold from the mandrel.

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

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 inner surface of the product is simplified (coating is applied by the electric arc method in air using a known high-performance installation) and does not require the use of special expensive equipment, and the manufacture of the product (molding and coating) is carried out in one cycle. In addition, the claimed method allows to manufacture products using binders "cold" curing.

The cost of products manufactured in this way, below known. The dimensions of the product during spraying and assembly are determined only by the dimensions of the mandrel, and in this case, compared with known methods, the manufacturing technology of such products is easier.

Sources of information

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

2. Patent JP 58160124, B 29 D 23/12, 09/22/1983 - prototype.

Claims (3)

1. A method of manufacturing a product from a composite material, comprising assembling a bag by winding layers of a reinforcing material impregnated with a thermosetting binder on the mandrel, and molding by curing the binder, characterized in that the inner surface is metallized by spraying the metal in air using the electric arc method on the mandrel, followed by winding package on the sprayed surface and curing the binder. 2. The method according to claim 1, characterized in that a layer of release agent is applied to the surface of the mandrel before spraying the metal. 3. The method according to claim 1 or 2, characterized in that they use a mandrel from a material with a high coefficient of thermal expansion, having an internal cavity for filling with liquid nitrogen.