RU2492340C1 - Method to manufacture inner heat-shielding coating of rocket engine body - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: in process of manufacturing of an inner heat-shielding coating of a rocket engine body, layers of unvulcanised rubber are laid onto a rigid mandrel on the basis of synthetic rubbers to make a packet of required thickness, and the produced packet is vulcanised. Roughing and degreasing of the vulcanised rubber packet surface is carried out. A solution is applied onto the treated surface, which is produced by mixing of ethyl acetate, benzene and rubber, with weight of 0.2-0.25 of the total solution mass. It is soaked at room temperature to produce tack of the applied solution. Additional layers of the unvulcanised rubber are laid with further vulcanisation within the rocket engine body.

EFFECT: invention makes it possible to increase quality of manufacturing of a heat-shielding coating of a solid propellant rocket engine.

2 cl, 2 dwg

Description

The invention relates to the field of rocket technology and can be used in the manufacture of internal heat-shielding coating (TZP) of rocket engine housings (RD), for example, on solid fuel (RTTT).

At present, the manufacture of an internal TZP of a solid propellant rocket hull with a power shell made of composite materials (see, L.N. Lavrov et al. "Design of solid propellant rocket engines", Moscow, "Mashinostroyenie", 1993, p. 63- 64), carried out in two stages: at the first stage, layers of unvulcanized rubber are layered layer-by-layer on a rigid mandrel to obtain a packet of the required thickness and the resulting packet is vulcanized to give it solidity and rigidity, and at the second stage, the resulting packet is placed on a washable sand mandrel (see for example, RF patent No. 2266201), apply the adhesive composition to the bag and lay additional layers of unvulcanized rubber on it, followed by vulcanization in the rocket engine body during the polymerization of its power shell.

Additional layers of unvulcanized rubber are a component of the internal TZP of the body, which forms the sealing layer of the body and the substrate, which provides stronger bonding with it of the composite material of the power shell when it is wound, as compared to winding directly on the vulcanized rubber layer.

A known method of manufacturing an internal TZP of large-sized products from composite materials, including layer-by-layer laying on a rigid mandrel of layers of unvulcanized rubber to obtain a package of the required thickness and vulcanization of the resulting package in a hydroclave (see, for example, I.M. Bulanov, V.V. Vorobey. Technology rocket and aerospace structures made of composite materials. - M.: Publishing House of MSTU named after NE Bauman, 1998 - p. 413, 418, 434-438).

In this method, elastic rubbers based on ethylene propylene and ethylene propylene diene rubbers are used.

There is also a known method of manufacturing an internal heat-shielding coating for a rocket engine housing, comprising layering layers of unvulcanized rubber on a rigid mandrel to obtain a packet of the required thickness and vulcanizing the resulting packet (RF patent No. 2415289), which is the closest analogue.

The known method has established itself well as the first stage in the manufacture of internal TZP of a highly deformable organoplastic RDTT case, including the use of modern rubbers based on synthetic rubbers, grades SKEP and SKEPT, which have increased heat resistance.

However, during autonomous tests of the new generation solid-state solid-propellant plastic-body case, operating at elevated temperature and pressure, in which the internal heat-resistant composite was made of rubber based on synthetic rubbers by applying adhesive to the surface of a vulcanized rubber package obtained in a known manner and laying additional layers of unvulcanized rubber on it for the formation of the sealing layer, the presence of unit bundles along the boundary of the package with additional layers was revealed.

It was found that delamination is formed due to the insufficient strength of bonding the surface of unvulcanized rubber to the surface of vulcanized rubber when gluing adhesive compositions based on chlorosulfonated polyethylene, for example, adhesive composition 51-K 45 (TU 38 1051955-90), widely used in known methods, are bonded developed by VNIEMI.

Thus, the known method does not provide the required strength of bonding of a package of vulcanized rubber with additional layers of unvulcanized rubber when manufacturing an internal TZP case, especially when using rubbers based on synthetic rubbers, which leads to a decrease in the quality of TZP manufacture.

Poor manufacturing quality of TZP is unacceptable for solid propellant rocket motors, which are especially critical products operating under stressful conditions.

It has been established that it is necessary to develop a new technology that provides increased bonding strength between rubbers based on synthetic rubbers, which are difficult to bond, and vulcanized rubber with unvulcanized (raw) is especially poorly glued to each other.

The technical task of this invention is to improve the manufacturing quality of the internal heat-shielding coating of the rocket engine housing, formed from layers of rubber based on synthetic rubbers, while ensuring the required manufacturability.

The technical result is achieved in that in a method for manufacturing an internal heat-protective coating of a rocket engine housing, including layering layers on a rigid mandrel of layers of unvulcanized rubber based on synthetic rubbers to obtain a package of the required thickness, vulcanizing the resulting package and laying additional layers of unvulcanized rubber on it, followed by vulcanization as part of the rocket engine housing, before laying additional layers of unvulcanized rubber, roughening and fattening the surface of the vulcanized rubber package and a solution obtained by mixing ethyl acetate, gasoline and rubber, weighing 0.2-0.25 of the total weight of the solution, is applied to the treated surface, kept at room temperature until formation of the stickiness of the applied solution is formed, after which additional layers are laid unvulcanized rubber.

The surface of the first of the additional layers of unvulcanized rubber to be laid is subjected to the same treatment as the surface of the vulcanized rubber package.

The application of the solution of the proposed composition, instead of glue, on the surface of the package of vulcanized rubber can increase the strength of its adhesion to unvulcanized rubber.

The use for the preparation of a solution of a mixture of ethyl acetate and gasoline, in a ratio of one to one, as a solvent, as shown by experiments, is preferable in comparison with other solvents.

Stirring the solution until a homogeneous state, applying the resulting solution on the bonded surface of the rubber and holding at room temperature until the solution reaches the stickiness of the solution allows you to optimally prepare the surface to ensure the best bonding between them.

Laboratory and experimental studies have confirmed the high efficiency of the proposed technology for bonding bonding between vulcanized and unvulcanized rubbers based on synthetic rubbers, while the tensile and shear strength indicators significantly exceed the similar parameters of the known technology in which an adhesive composition is used for bonding rubbers.

It is empirically established that the necessary value of adhesion strength of rubbers is achieved using a solution in which the content of the rubber used is 20-25 weight percent of the total weight of the solution.

An increase in the adhesion strength of vulcanized and unvulcanized rubbers is ensured due to the surface introduction of a solution heated during vulcanization into them, and a rubber mass is formed having a monolithic structure without an adhesive border, which is confirmed by the preparation of samples of the manufactured internal heat-protective coating.

Carrying out the surface treatment of the first of the stacked additional layers of unvulcanized rubber, similar to the surface treatment of a package of vulcanized rubber, can additionally increase the adhesion strength of rubbers and may be especially appropriate when using rubber packs based on synthetic rubbers of different grades for a TPP package.

The essence of the method is illustrated by drawings.

Figure 1 shows the manufacturing scheme of the package TZP.

Figure 2 shows a diagram of the manufacture of internal TZP case.

A method of manufacturing an internal TZP of a solid propellant rocket motor enclosure is as follows.

Marked according to templates and cut out of unvulcanized (crude) rubber based on synthetic rubbers, SKEPT brand, the required number of blanks 1 of the required size to form a packet 2 of a given thickness and the required number of blanks 3 of the required size to form a given thickness of the additional layer 4 laid on the packet 2.

On a rigid metal mandrel 5 layer-by-layer package 2 is applied, consisting of blanks 1 of unvulcanized rubber.

In this case, before laying out the surface of the workpieces 1 are refreshed with gasoline.

Set the flange 6 and place the mandrel 5 in the hydroclave (not shown in Fig.), Put the lid 7, seal the hydroclave.

Vulcanization is carried out in a hydroclave of the package 2 laid out in this way to give it solidity and rigidity.

After vulcanization, the mandrel 5 with the package 2 is removed from the hydroclave, the package 2 is removed from the mandrel 5 and placed on a rigid sand mandrel 8, the external profile of which is identical to the internal profile of the load-transfer protection of the power shell of the housing.

Expose the outer surface of the package 2 mechanized roughing and degrease the surface with nephras, followed by exposure for 15-30 minutes.

Prepare a solution of the unvulcanized rubber used in a mixture of ethyl acetate and gasoline, at a one to one ratio, as follows: take a weight of rubber weighing 20-25 grams, cut into squares (15 × 15) mm, fill with a mixture of ethyl acetate and gasoline in an amount of 75- 80 grams and produce regular mixing until a homogeneous solution.

A layer 9 of the resulting solution is applied to the outer fat-free surface of the packet 2 and kept at room temperature (18-25 ° C) until confectionary tack is achieved.

Spread on the outer surface of the package 2 the required number of blanks 3 unvulcanized rubber to obtain the required thickness of the additional layer 4.

In this case, before laying the surface of the workpieces 3 are refreshed with gasoline.

A power shell 10 of the housing is made by winding the polymer composite material onto an additional layer 4, and rubber is vulcanized during the polymerization of the power shell 10 of the rocket engine housing.

After cooling, the sand mandrel 8 is washed out and ultrasonic quality control of the manufacture of internal heat-resistant composite is performed for the presence of delamination and cracks.

The use of the invention allows to improve the manufacturing quality of the internal heat-shielding coating of the solid propellant rocket motor formed from rubber based on synthetic rubbers, while ensuring the required manufacturability.

Claims (2)

1. A method of manufacturing an internal heat-shielding coating for a rocket engine housing, comprising layering layers of unvulcanized rubber based on synthetic rubbers on a rigid mandrel to obtain a package of the required thickness, vulcanizing the resulting package and laying additional layers of unvulcanized rubber on it with subsequent vulcanization as a part of the rocket engine housing, characterized in that before laying additional layers of unvulcanized rubber, roughening and degreasing of the surface a package of vulcanized rubber and a solution obtained by mixing ethyl acetate, gasoline and rubber, weighing 0.2-0.25 of the total weight of the solution, is applied to the treated surface, kept at room temperature until the formation of the stickiness of the applied solution, and then additional layers of unvulcanized rubber are laid . 2. A method of manufacturing an internal heat-shielding coating of a rocket engine housing according to claim 1, characterized in that the surface of the first of the stacked additional layers of unvulcanized rubber is subjected to the same treatment as the surface of the package of vulcanized rubber.

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