RU2384410C1 - Method of shaping mandrel preparation for operation - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: in process of shaping mandrel preparation for operation, where mandrel is intended to manufacture products from composite materials, organosilicon lubricant is dissolved in benzine in amount of 5 vol % from the total volume of solution and is mixed to produce homogeneous solution. Produced solution is applied onto surface of shaping mandrel after its degreasing and is maintained in air for at least 30 minutes. Afterwards shaping mandrel is placed into heat furnace, is heated up to the temperature of 180 - 200°C and maintained in furnace at this temperatire for 2-3 hours.

EFFECT: required quality of shaping mandrel working surface by development of a strong anti-adhesion coating, which eliminates ingress of binder onto surface of shaping mandrel in process of part manufacturing, thus providing for easy removal of hardened stock with optimal ratio of complexity, labour intensiveness and cost of works performance.

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Description

The invention relates to the technology of manufacturing parts from composite materials (CM), namely shells for power structures, mainly parts of nozzle blocks of rocket engines for solid fuel (solid propellant rocket engines).

In the manufacture of parts from KM, a tape of a starting material impregnated with a binder, for example carbon fabric, is wound onto a forming mandrel, cured by temperature and pressure, cured, and the resulting preform is removed from the mandrel.

Thorough preparation of the forming mandrel for work is one of the main stages of the cycle of manufacturing parts from KM.

In this case, before winding the tape of the source material on the working surface of the forming mandrel (the surface in contact when manufacturing parts from CM with the source material), a release coating is applied to avoid strong adhesion of the cured workpiece to the forming mandrel.

The release coating is applied after degreasing the surface of the forming mandrel.

There is a method of preparing for work a forming mandrel designed for the manufacture of products from composite materials, including degreasing the surface of the forming mandrel and applying a release coating on it (I.M. Bulanov, V.V. Vorobey. Technology of rocket and aerospace structures from composite materials. - M .: Publishing house of MSTU named after N.E.Bauman, 1998, p. 132, 133, 142) - prototype.

In the known method for applying to the surface of the forming mandrel various types of release coatings can be used, selected depending on the type of material from which the forming mandrel is made, the type of binder used to impregnate KM, and other factors.

The known method is used in the manufacture of a number of products from KM.

However, the known method does not provide acceptable for the manufacture of particularly critical parts of solid propellant rocket engines from KM surface quality of the forming mandrel, which is associated with insufficient strength of the applied anti-adhesive coating.

The increased requirements for the strength of the release coating are due to the need in the manufacture of composite parts of the nozzle blocks of solid propellant rocket composite materials to use a hot cure binder for impregnation of the starting material and curing under the influence of high temperature and pressure.

The destruction of the release coating during the manufacturing of parts from KM leads to the binder getting onto the surface of the forming mandrel, which complicates the process of removing the cured workpiece due to its adhesion to the forming mandrel.

Thus, the application of the known method does not allow to obtain the required surface quality of the forming mandrel while ensuring the optimal ratio of complexity, complexity and cost of work in the manufacture of CM parts of solid propellant.

The technical task of this invention is to obtain the required surface quality of the forming mandrel by creating a durable release coating while ensuring the optimal ratio of complexity, complexity and cost of work in the manufacture of CM parts of solid propellant rocket motors.

The technical result is achieved by the fact that in the method of preparing for work the forming mandrel, intended for the manufacture of products from composite materials, including degreasing the surface of the forming mandrel and applying a release coating on it, dissolve the silicone grease in gasoline in an amount of 5 volume percent of the total solution volume, mix until a homogeneous solution is obtained, the resulting solution is applied to the surface of the forming mandrel after degreasing it; in air for at least 30 minutes, the forming mandrel is placed in a thermal oven, producing temperatures up to 180-200 ° C and held in an oven at this temperature for 2-3 hours.

Dissolution of organosilicon lubricant in gasoline makes it possible to obtain an optimal solution from the point of view of creating the best release coating on the working surface of the forming mandrel, which excludes the binding of the binder to the surface of the forming mandrel and provides easy removal of the cured workpiece from KM.

It has been empirically established that the monolithic structure of the release coating is achieved by using a solution in which the content of organosilicon lubricant (type K-21) is 5 volume percent of the total volume of the solution.

Degreasing the surface and holding for at least 30 minutes allow you to best prepare the surface of the forming mandrel to ensure uniform application of the solution.

Heating to a temperature of 180-200 ° C and holding at this temperature for 2-3 hours allow you to create a strong release coating on the surface of the forming mandrel, while ensuring uniform temperature effects in the heat furnace.

The developed sequence of operations allows you to create a release coating (protective film) on the surface that persists with repeated use of the forming mandrel, which is confirmed by calculation and experimental methods.

The drawing shows a forming mandrel, prepared for work.

The method of preparation for operation of the forming mandrel, intended for the manufacture of products from composite materials, is as follows.

Inspect the steel forming mandrel for any damage on its surfaces. Clean surfaces from dirt and dust.

Wipe the working surface 1 of the forming mandrel with a cloth soaked in gasoline. The silicone grease (type K-21) is drained in an amount of 5 volume percent and gasoline in an amount of 95 volume percent in a metal container.

Mix thoroughly until a homogeneous solution is formed. The solution is stored in a sealed container for no more than 24 hours. When preparing the forming mandrel for work, the solution is applied to the dried and fat-free working surface 1.

The solution layer should be evenly distributed over the working surface 1 of the forming mandrel. Maintain the forming mandrel in the air for at least 30 minutes.

Put the forming mandrel with the applied solution in a thermal oven. They are heated to a temperature of 180-200 ° C and kept in an oven at this temperature for 2-3 hours. Cool the forming mandrel to a temperature of 40 ° C and take out the forming mandrel with the obtained release coating 2 from the heat furnace.

Close the forming mandrel with an opaque cover and store the forming mandrel prepared for work until the beginning of the manufacturing process of products from KM.

In the manufacture of products from KM, a URAL-T-22 carbon fabric tape, pre-impregnated with a binder of the FN grade, is wound onto a forming mandrel with a release coating coated, and the forming mandrel is placed in an autoclave, where curing is carried out under the influence of elevated temperature and pressure.

After exposure and cooling, a mold-forming mandrel with the obtained preform is removed from the autoclave. Then the workpiece is removed from the forming mandrel without significant effort, which eliminates the possibility of damage to the inner surface of the workpiece.

Prepared by the proposed method, the forming mandrel can be used repeatedly without additional coating.

The proposed method allows to obtain the required surface quality of the forming mandrel while ensuring the optimal ratio of complexity, complexity and cost of work in the manufacture of CM parts of solid propellant rocket motors.

The practical application of the invention has confirmed the high adaptability of the proposed method for preparing a forming mandrel for the manufacture of products from composite materials.

Claims (1)

A method for preparing a forming mandrel intended for the manufacture of products from composite materials, including degreasing the surface of the forming mandrel and applying a release coating on it, characterized in that they dissolve the silicone grease in gasoline in an amount of 5% of the total solution volume, mix until a homogeneous solution is obtained , the resulting solution is applied to the surface of the forming mandrel after its degreasing, incubated in air for at least 30 minutes, place the moldoo razuyuschuyu mandrel to heat the furnace, producing temperatures up to 180-200 ° C and held in an oven at this temperature for 2-3 hours.