FI20185184A1 - Method for reinforcement of a composite product - Google Patents

Abstract

The object of the invention is a method of strengthening a composite product, in which method a combination of at least one mold (1) and a composite product (2) placed against it is lowered into liquid (II) in the vessel (10) and said combination. the depression depth (d) from the surface (11) of the liquid (11) is selected so as to cause a desired large hydrostatic beverage to act on the surface of the composite product (2.1), the pressure of which is kept constant for a certain time or the size of which is changed during the reduction by vary the depression depth (d) and said combination is kept lowered in the liquid (11) for a certain advantageous time to strengthen the composite product (2). In another use of the invention, the said combination is enclosed with a gas-tight membrane (3) prior to immersion in the liquid (11) and inside the membranes a vacuum duct (8) is passed through, which pierces the membranes which are joined to a vacuum unit (15) and a vacuum is made. inside the membranes (3) by means of vacuum unit (15) and by vacuum duct (8) and by composite product (2) surrounded by membrane (3) is maintained in action by vacuum during the lowering time of the composite product or part of this time to strengthen the composite product.

Description

METHOD FOR STRENGTHENING A COMPOSITE PRODUCT

20185184 PRH 27-02-2018

The present invention relates to a method for reinforcing a composite product, in which method a composite product placed against a mold is fitted to a container in which an overpressure is applied to the surface of the composite product.

Reinforcement of the composite product may mean, for example, curing, post-curing, increasing the tightness or other strength-improving treatment. Some of the resins used in the manufacture of composites require final curing by heat treatment and / or overpressure.

The invention is used to strengthen the structures of various composite products formed by mold. Such composite products can be, for example, parts formed of fiber and resin or rubber composite parts, etc. They can be used, for example, in cars and aircraft, sports equipment, parts of the electronics industry, building elements, etc.

It is known that when forming high strength composite products, they are treated with overpressure and at temperatures above normal room temperature. Such treatment is known to be carried out in an autoclave. A suitable autoclave is a pressure vessel that is hermetically sealed on the deck or door, where the composite product is usually heated with steam. The purpose of the treatment is to speed up and intensify certain reactions in the product.

The prior art described above is very commonly used in the reinforcement of composite products. The semi-finished products or the composite product in its almost final form and its mold are sealed in an autoclave, an overpressure is produced inside it and the internal temperature is raised, e.g., slightly above 100 ° C. The pressure temperature inside the autoclave affects the composite product e.g. so that the product presses against the mold 30 and certain ingredients in the product change or come loose when heated. As a result, air and other harmful substances are removed from the product and the strength values of the product are improved. The composite product can also obtain its final exact shape during processing.

20185184 PRH 27-02-2018

In carrying out the prior art described above, the size of the autoclave should be adapted to the size of the composite product being processed therein. The overpressures used in autoclaves are typically from one bar upwards and the temperatures 121-123 ° C.

The major drawback of the prior art can be considered to be that it places a limit on the size of the composite product that can be treated with it. The bigger the product, the bigger the autoclave needed. The autoclave is a pressure vessel and the manufacturing cost of a large, safe autoclave is very high. Similarly, its maintenance costs10, such as energy costs, inspection and control costs, increase sharply as the size increases. The pressure vessel must meet the high safety requirements set by the pressure vessel regulation, e.g. for multiple strength requirements. The secure design of the often openable lid / door of the autoclave complicates the design of the device. There is always a safety risk associated with using an autoclave.

The higher the pressure to be applied in the autoclave, the higher the risks have to be taken and the higher the costs have to be accepted.

It is an object of the present invention to provide a method for reinforcing a composite product which avoids the disadvantages of the prior art. The solution according to the invention is characterized by what is set forth in the characterizing part of claim 1.

The method according to the invention has several significant advantages over the prior art. The devices used in the method according to the invention are very simple in structure and inexpensive to build and maintain. They can also handle very large composite products and do not present an explosion hazard.

A significant advantage in the use of the invention is achieved in that other composite product reinforcement measures, which are difficult to combine with autoclave treatment, can be easily incorporated into the method according to the invention.

20185184 PRH 27-02-2018

In summary, the advantages of the invention can be used to produce high-strength composite products almost safely without limiting the physical size of the products.

The term “heat transfer fluid” also includes a substance that transfers cold.

The invention is described in more detail in the accompanying drawings, in which Fig. 1 shows an apparatus used in the method according to the invention, Fig. 2 shows in more detail an apparatus in which a composite product is treated, Fig. 3 shows a method for carrying out the method according to Fig. 1,

In the following, a preferred embodiment of the method according to the invention and the operation of the equipment used therein will be explained with reference to the above-mentioned figures.

Figure 1 illustrates an apparatus for carrying out the method according to the invention. The apparatus comprises a deep vessel 10 which is open at its upper end 10.1. The container is filled with liquid 11, which in this example is water. Above the surface of the liquid 11.1 there is a processing unit 13 attached to the lifting device 12, which is described in more detail in Fig. 20. The processing unit 13 has a mold 1 inside and a composite product 2 arranged around the mold, which in this example comprises fiber bars and resin. The composite product is surrounded by a gas-tight film 3 and a pressure-permeable thermal insulator 4 is arranged around the mold, the composite product and the film so that a closed space 5 is left between the composite product and the thermal insulator. a vacuum duct 8 is passed through the thermal insulation and said membrane. The supply duct 7a, the outlet duct 7b and the vacuum duct 8 are flexible hoses in this example. The supply and discharge ducts 7a, 7b are connected to the heat transfer fluid supply unit 14 and the vacuum duct 8 is connected to the vacuum unit 15.

The method according to the invention works as follows when using the apparatus described above: the treatment unit 13 is immersed in the liquid 11 in the vessel 10 to a certain depth from the liquid surface 11.1, the space 5 being filled with liquid flowing through the thermal insulator 4 and the composite product 2

20185184 PRH 27-02-2018 rose depends on the immersion depth d of the composite product. In the situation according to Figure 3, the liquid 11 is water and the immersion depth d of the composite product is on average 10 meters, whereby the overpressure applied to the surface 2.1 of the composite body is about 1 bar (100 KPa). The composite product presses against the mold under overpressure and certain components in the product, such as air in air bubbles, are pressed onto its surface. At the same time as the hydrostatic pressure acts on the composite product, a vacuum unit 15 is started, whereby a vacuum created in the vacuum unit is created in the vacuum duct 8 and inside the membrane 3. Adverse components that have risen and rise to the surface of the composite product 2.1, such as air, are transferred out of the composite product 2 through the vacuum duct 8 10. As a result, the product removes gases and other harmful substances, the product condenses and the strength values of the product improve.

In addition to the above-mentioned measures, according to Fig. 3, by means of the supply unit 14 15 and through the supply channel 7a and the outlet channel 7b, the heat transfer liquid 6 at a higher temperature 11 can be circulated to and from the space 5. When the heat transfer fluid releases thermal energy in space 5, the temperature of the composite product 2 rises. The thermal insulator 4 prevents the transfer of thermal energy outside the processing unit 13.

The heat transfer fluid 6 recyclable as mentioned above can be utilized in another embodiment of the present invention by bringing it to a temperature lower than the temperature of the liquid 11 before feeding the supply duct 7a, whereby the composite product 2 is cold treated with pressure transfer. The function of the thermal insulation 4 is then to slow down the transfer of thermal energy from the liquid 11 to the heat transfer fluid 6, i.e. to prevent the heat transfer fluid from heating up. Cooling is a means known per se for curing and / or reinforcing a composite product. Thus, the term “heat transfer fluid” in this document also includes a substance that transfers cold instead of heat to a treatment unit 30 13.

When all the above-mentioned measures are carried out either simultaneously, alternately or partially alternately, the overpressure applied to the composite product 2, the si

20185184 PRH 27-02-2018 The internal vacuum and heat and / or cold treatment together create a sealing, strengthening and hardening effect of the composite product.

Deviating from the above, the invention can also be applied in such a way that the composite product 2 is subjected to only the above-mentioned overpressure treatment, whereby the combination 11 formed by the mold 1 and the composite product 2 is immersed in the liquid 11 as such or placed in the treatment unit 13.

The invention can also be applied in such a way that the composite product 2 undergoes the above-mentioned overpressure and underpressure treatments, but not the heat or cold treatment. In this case, the combination of the mold 1, the composite product 2 and the film 3 is immersed in the liquid 11 as such or placed in the processing unit 13.

The invention can also be applied in such a way that the composite product 2 is subjected to the above-mentioned overpressure and heat and / or cold treatments, but not to the vacuum treatment. In this case, a treatment unit 13 is immersed in the liquid 11, which contains at least a combination of the mold 1 and the composite product 2.

If desired, the equipment used in the method according to the invention can be adapted to the method steps to be carried out.

The overpressure, underpressure and heat or cold treatments described above can thus be carried out simultaneously, alternately, intermittently or gradually in the process according to the invention. The pressure on the composite product 2 can be changed during the treatment by changing the immersion depth d, and the heating / cooling effect on the composite product can be changed by changing the temperature of the heat transfer fluid 6 fed to the supply duct 7a.

The duration of the overpressure treatment to be applied to the composite product 2 may be, for example, 1 to 2 hours or 1 to 5 hours when applying the present invention, but its duration is not limited to these time ranges when using the invention. Vacuum and / or heat treatment can last all or part of the overpressure treatment.

20185184 PRH 27-02-2018

The liquid 11 used in the invention may be water or a mixture containing water and some other substance, such as, for example, a refrigerant. The hydrostatic pressure caused by the liquid 11 is known to be directly proportional to the immersion depth d and the density of the liquid.

As an example of the preferred immersion depths d used in the method according to the invention, mention may be made of 10 to 50 meters, whereby the hydrostatic pressure becomes about 1 to 5 bar when the liquid 11 is water.

The vessel 10 can be implemented, for example, in a tower or well structure, and in its implementation, differences in the height of the terrain can be utilized. Vessel 10 can also be a natural water pool, such as a lake or sea. When the above-mentioned natural water pool is used as a vessel 10, the immersion of the composite product 2 can be performed e.g. from a ship, whereby it is easy to implement a very large immersion depth d. With the above-mentioned solutions, immersion depths d of more than one hundred meters can advantageously be achieved.

The membrane 3 can be a vacuum bag or a flexible injection-molded membrane, which is particularly suitable for composite products 2 of complex shapes. The membrane 3 is characterized in that it is gas-tight. The film can be implemented in many known ways.

As the heat transfer fluid 6, for example, Globaltherm products can be used, the operating temperatures of which are -90 ° C (Globaltherm C) to 600 ° C (Globaltherm Omnistore MS-600), depending on the product. Other options include e.g. water and various oils and their mixtures. From the available alternatives, a non-toxic and non-combustible alternative can be selected as the heat transfer fluid 6. The temperature of the heat transfer fluid can be, for example, -90- +600 ° C when fed. The temperature of the heat transfer fluid can always be selected to suit the case.

The supply unit 14 may be provided with a heating or cooling device for the heat transfer fluid 6, or the heating / cooling device for the heat transfer fluid may be carried out elsewhere, from where it is led at a certain temperature to the supply unit 14 and returned from the unit in its rotated state 5.

All of the above-mentioned embodiments of the method according to the invention can be combined with the rotation of the composite product 2 to ensure pressure and other

20185184 PRH 27-02- 2018 uniform effect of the effects on its different parts. The rotation can be realized, for example, by rotating the processing unit 13 back and forth horizontally.

The thermal insulation 4 can be implemented as a separate housing structure, as shown in the examples above, or it can be connected to the mold 1. It is characterized in that it transmits hydrostatic pressure, prevents the transfer of thermal energy to the outside or inside it and that a space 5 is formed between it and the composite product 2 for the heat transfer fluid 6. An example of a thermal insulation applied to the mold 1 is a flexible or rigid thermal insulation layer attached to the mold, the interior space 5 of which is a cavity / cavities extending to at least a part of the surface 2.1 of the composite product 2.

The vacuum unit 15, which produces a vacuum in the vacuum duct and further inside the membrane 3, is e.g. a vacuum cleaner.

The effects of pressure, vacuum and temperature changes on the composite product 2 can be monitored during the process, e.g. with pressure and temperature sensors as well as infrared sensors and cameras. If necessary, other monitoring devices and methods according to the prior art can also be adapted for monitoring. Based on the control results obtained20, the process can be adjusted as desired, either manually or automatically.

A computer or similar data processing device can be used to implement the automatic adjustment.

It should be noted that while this description has followed one type of preferred embodiment of the invention, it is not intended to limit the use of the invention to this type of example, but many modifications are possible within the scope of the inventive idea defined by the claims.

Claims (15)

The claims A method of reinforcing a composite product, the method comprising placing a composite product placed against a mold in a container in which the surface of the composite product is 5 is subjected to an overpressure characterized in that a. a combination comprising at least a mold (1) and a composite product (2) is immersed in a liquid (11) in a container (10), b. the immersion depth (s) (d) of said combination, measured from the surface (11.1) of the liquid (11), is selected so as to achieve a composite of the desired size; 10 hydrostatic pressure acting on the surface (2.1) of the product, the magnitude of which is kept constant for a certain time or the magnitude of which is changed during immersion by changing the immersion depth (d), c. said combination is kept immersed in the liquid (11) for a certain preferred period of time to strengthen the composite product (2). Method according to Claim 1, characterized in that a. before immersing said combination in the liquid (11), a gas-tight membrane (3) is surrounded and a vacuum passage (8) piercing the membrane is introduced inside the membrane and connected to the vacuum unit (15), 20b. A vacuum is created inside the membrane (3) by means of a vacuum unit (15) and via a vacuum duct (8), c. the composite product (2) surrounded by the film (3) is considered to be under vacuum under the immersion time of the composite product or a part of this time to strengthen the composite product. Method according to Claim 1 or 2, characterized in that: a. A pressure-permeable thermal insulator (4) is arranged around the mold (1) and the composite product (2) or a combination of the mold (1), the composite product (2) and the film (3) so that between the composite product and the thermal insulator 30 a closed space (5) is formed, b. a supply channel (7a) and an outlet channel (7b) for the heat transfer fluid (9) are passed through the thermal insulation (4) to the space (5) and are connected to the heat transfer fluid supply unit (14), 20185184 PRH 27-02-2018 c. a liquid (11) heat transfer fluid (6) at a higher or lower temperature is circulated through said space (5) to raise or lower the temperature of the composite product (1). Method according to one of Claims 1 to 3, characterized in that the immersion depth (d) of the composite product (2) is changed during immersion. Method according to Claim 3 or 4, characterized in that the heat transfer fluid (6) is circulated through the space (5) during all or part of the immersion. Method according to one of Claims 1 to 5, characterized in that the liquid (11) is water, a mixture of water and refrigerant or another liquid suitable for the conditions. Method according to one of Claims 1 to 6, characterized in that the immersion depth (d) is 10 to 100 meters. Method according to one of Claims 1 to 7, characterized in that the immersion time is 1 to 5 hours. Method according to one of Claims 2 to 8, characterized in that the film (3) is a plastic bag or a plastic film formed by spraying on the surface of a composite product (2). Method according to one of Claims 2 to 9, characterized in that the vacuum unit (15) is a vacuum cleaner. Method according to one of Claims 3 to 10, characterized in that the thermal insulation (4) forms a separate housing or is arranged in connection with the mold. Method according to one of Claims 3 to 11, characterized in that the heat transfer fluid (6) is Globaltherm C, Globaltherm Omnistore MS-600 or another Globaltherm product or water or oil or a mixture of the above. ίο Method according to one of Claims 3 to 12, characterized in that the supply duct (7a), the outlet duct (7b) and the vacuum duct (8) are flexible hoses. Method according to one of Claims 3 to 13, characterized in that The supply unit (14) 5 comprises heating and / or cooling devices for the heat transfer fluid (6). Method according to one of Claims 3 to 14, characterized in that the temperature of the heat transfer fluid (6) is from -90 ° C to + 600 ° C.