WO2020178948A1

WO2020178948A1 - Vacuum bag and method for manufacturing vacuum bag

Info

Publication number: WO2020178948A1
Application number: PCT/JP2019/008399
Authority: WO
Inventors: 豊久内尾
Original assignee: 日本飛行機株式会社
Priority date: 2019-03-04
Filing date: 2019-03-04
Publication date: 2020-09-10
Also published as: JP6625300B1; JPWO2020178948A1

Abstract

Provided is a vacuum bag which is lightweight, has excellent workability, and can be easily manufactured and reused. This vacuum bag 10 is composed of a diaphragm 11, a frame 12, and a seal 13. The frame 12 is composed of a fiber-reinforced plastic laminate structure 20. The fiber-reinforced plastic laminate structure 20 is covered with a non-silicon-based thermosetting synthetic rubber 26. The curing temperature region of the synthetic rubber 26 and the curing temperature region of the thermosetting resin of the laminate structure 20 overlap each other. Consequently, the synthetic rubber 26 and the laminate structure 20 are molded in one body. In the same step, the synthetic rubber 16 is adhered to the silicon-based diaphragm 11. That is, the vacuum bag 10 is easily manufactured by one-body molding. In particular, when a jig base 30 has a free surface, the effect of easy manufacture becomes remarkable.

Description

Vacuum bag and method of manufacturing vacuum bag

The present invention relates to a vacuum bag used when heat and pressure molding a fiber reinforced plastic laminate.

In recent years, fiber reinforced plastics such as carbon fiber reinforced plastic (CFRP) (Carbon Fiber Reinforced Plastics) have been receiving attention. Utilizing the features of light weight and high strength, it is applied to various industrial fields as a material for aircraft and automobiles. In addition, glass fiber, quartz glass fiber, and aramid fiber may be used.

A brief explanation will be given of an example of a method for forming a fiber-reinforced plastic laminate. A prepreg sheet laminated body is laminated on a jig stand and shaped into a product shape. The prepreg sheet is formed by impregnating a reinforcing material such as carbon fiber with an uncured thermosetting resin, and is formed into a sheet shape.

Unsaturated polyester, epoxy resin, phenol resin, etc. are used as the thermosetting resin.

Furthermore, the shaped fiber-reinforced plastic laminate is bagged together with the jig table, evacuated, conveyed to an autoclave device, and heated and pressed. As a result, the resin is cured and the fiber-reinforced plastic laminate is molded. Demold the product each time.

Note that thermoplastic resin such as polyamide resin or polypropylene resin may be used instead of the thermosetting resin. The thermoplastic resin is softened by heating and then solidified by cooling.

A vacuum bag is used for evacuation (Patent Document 1). The vacuum bag uses a polymer film such as nylon or a diaphragm made of a silicon material.

Tokuyohei 8-506534

Generally, the vacuum bag is discarded after each heating/pressurizing step, and a new vacuum bag is used in the next heating/pressing step. As a result, it is reflected in the product manufacturing cost. Further, the disposal cost is also reflected in the product manufacturing cost.

On the other hand, a reusable vacuum bag has been proposed. Currently available vacuum bags include a metal frame that supports the diaphragm. However, the vacuum bag having a metal frame has the following problems.

Generally, members such as airplanes and automobiles are large, and if the vacuum bag also increases in size, the weight of the metal frame also increases. As a result, workability such as attachment / detachment of the vacuum bag is reduced. That is, there are problems related to weight and workability.

Also, after the metal frame is manufactured, the manufacturing process is complicated because it goes through multiple processes such as bonding the diaphragm to the metal frame.

By the way, members such as aircraft and automobiles have complicated shapes such as free-form surfaces. The details of the free-form surface will be described later.

If the product has a free-form surface, the jig base must also have a free-form surface, and the frame must also support the free-form surface. Although it is possible to process a metal into a complicated frame shape such as a free-form surface, the processing is not easy. The manufacturing process becomes more complicated.

If the vacuum bag manufacturing process becomes complicated, it will affect the product cost. As described above, there is a problem related to the ease of manufacturing.

The present invention is intended to solve the above problems, and an object thereof is to provide a reusable vacuum bag that is lightweight, has excellent workability, and is easy to manufacture.

The present invention, which solves the above-mentioned problems, is a vacuum bag used for vacuuming a fiber sheet laminated on a jig stand. A diaphragm made of a silicon-based material that covers the fiber sheet, a frame that supports the diaphragm, and a seal provided on the lower surface of the frame along the frame are provided, and the frame has a fiber-reinforced plastic.

Light weight as the frame has fiber reinforced plastic. As a result, the work of attaching and detaching the vacuum bag is easy and the workability is excellent.

Preferably, the portion of the frame made of fiber reinforced plastic is covered with non-silicon synthetic rubber, and the curing temperature range of the synthetic rubber and the curing temperature range of the resin used for the fiber reinforced plastic overlap.

　Non-silicon synthetic rubber has a high affinity with fiber reinforced plastics. The fiber-reinforced plastic and synthetic rubber of the frame are integrally molded by heat and pressure molding. Further, in the same step, the synthetic rubber and the diaphragm are bonded. That is, it is easy to manufacture.

Preferably, fibers are arranged in one direction in the longitudinal direction of the frame in the part made of fiber reinforced plastic of the frame.

As a result, the straightness of the fiber can counter the external force.

Preferably, the portion of the frame made of fiber reinforced plastic is interposed between the first layer and the second layer in which the fibers are arranged in one direction of the frame longitudinal direction, and the first layer and the second layer, A third layer in which the fibers have a woven structure is laminated to be formed.

With such a sandwich structure, the straightness of the fibers resists external force and the fabric structure suppresses strain and cracks.

Preferably, the jig base has a free curved surface, and the frame has a shape corresponding to the free curved surface of the jig base.

If the jig base has a free surface, the effect of facilitating manufacturing becomes remarkable.

The present invention that solves the above problems is a vacuum bag manufacturing method. The vacuum bag includes a diaphragm made of a silicon-based material that covers a fiber sheet for a product, a frame that supports the diaphragm, and a seal that is provided on the lower surface of the frame along the frame, and the frame is fiber-reinforced. It is formed by covering a portion made of plastic with a non-silicon synthetic rubber. A first non-silicon synthetic rubber sheet, a plurality of fiber sheets for a prepreg-shaped frame, a second non-silicon synthetic rubber sheet, an adhesive film, and a diaphragm are laminated in this order on a jig stand to form a laminate, The laminate is heated and pressurized in a vacuum state by covering it with another vacuum bag, and integrally molded.

The reusable vacuum bag according to the present invention is easily manufactured by integral molding using an autoclave device used for manufacturing a product, through a process similar to that of manufacturing a product.

The reusable vacuum bag according to the present invention is lightweight and has excellent workability.

The reusable vacuum bag according to the present invention is easily manufactured by integral molding.

Vacuum bag schematic diagram Detail of vacuum bag Detailed structure of laminated structure Vacuum bag manufacturing method explanatory drawing Illustration of how to use the vacuum bag Heating and pressurizing profile in autoclave equipment

-Vacuum bag configuration-
FIG. 1 is a partial cross-sectional perspective view showing a schematic configuration of the vacuum bag 10. The vacuum bag 10 is composed of a diaphragm 11, a frame 12 (partially sectional view), and a seal 13 (see FIG. 2).

The diaphragm 11 covers the fiber-reinforced plastic laminate before molding. Made of silicon material. Other materials may be used as long as they have the same stretchability, flexibility and heat resistance as silicon-based materials.

The frame 12 is bonded to the peripheral edge of the diaphragm 11 to support the diaphragm 11. Details will be described later separately.

The seal 13 is provided on the lower surface of the frame 12 along the frame 12. At the time of evacuation, it is elastically deformed to ensure the sealing property between the surface of the jig base 30 and the vacuum bag 10.

The diaphragm 11 and the seal 13 may be equivalent to those of the conventional technology. That is, the vacuum bag 10 of the present embodiment is characterized in that the frame 12 has a fiber reinforced plastic.

-Fiber reinforced plastic-
The frame 12 is made of fiber reinforced plastic. The fiber reinforced plastic is obtained by laminating prepreg sheets and heat-pressing them.

FIG. 3 is a schematic view of the laminated structure 20 of the prepreg sheet of the frame 12.

The laminated structure 20 includes a first layer 21 that is a first prepreg sheet, a second layer 22 that is a second prepreg sheet, and a third layer 23 that is a third prepreg sheet. Each of the layers 21 to 23 includes a case where a single prepreg sheet is formed and a case where a plurality of prepreg sheets are laminated and formed.

In the first layer 21 and the second layer 22, the fibers are arranged in the frame longitudinal direction unidirection (UD).

Since the first layer 21 and the second layer 22 do not have a woven structure, the fibers can maximize linearity with respect to external force. In the case of the woven structure, the fibers rise and fall in the vertical direction, so that the straightness cannot be exhibited. There is a risk that the counterforce will be dispersed.

In the third layer 23, the fibers are arranged in the longitudinal and transverse directions and have a woven structure, for example, plain weave (PW). The third layer (PW layer) 23 is interposed between the first layer 21 (UD layer) and the second layer 22 (UD layer). The laminated structure 20 has a sandwich structure. A plain weave is given as a representative example of the woven structure, but the present invention is not limited to this.

By interposing a woven structure, the strain in the first layer 21 and the second layer 22 is suppressed, and the generation of cracks is suppressed.

The laminated structure 20 of the present embodiment has a sandwich structure of UD layer-PW layer-UD layer, but may have a sandwich structure of PW-UD-PW. Further, only the UD layer may be used.

It is preferable that the thermosetting resin of the prepreg is thermoset at about 180° C. (±20° C.) due to the relationship with the curing temperature range of synthetic rubber (detailed separately). Further, the thermosetting resin preferably has a heat resistance of about 200 ° C. (± 20 ° C.). As a specific example, an epoxy resin EP, a cyanate ester resin, a bismaleimide resin, a benzoxazine resin, etc. are assumed.

-Synthetic rubber coating-
The fiber-reinforced plastic part 20 of the frame 12 is preferably covered with a thermosetting non-silicon synthetic rubber 26. However, the non-silicon synthetic rubber may contain a small amount of silicon component to the extent that the physical properties are not affected.

Regarding the curing temperature, it is preferable to heat cure in the autoclave device used for product manufacturing. For example, it is preferably thermoset at about 180 ° C. (± 20 ° C.). Further, it is preferable to have heat resistance of about 200 ° C. (± 20 ° C.).

In the prototype model, the product name "Air Pad Rubber" of Airtech International Co., Ltd. was used. The air pad rubber is an uncured non-silicon synthetic rubber, is heated to 176° C., is pressurized to 0.6 MPa, is hardened in about 2 hours, and has heat resistance of 204° C.

Note that synthetic rubbers with high heat resistance include acrylic rubbers ACM, ANM, ethylene vinyl acetate rubber EVA, epichlorohydrin rubber CO, ECO.

It is preferable that the curing temperature range of the synthetic rubber 26 and the curing temperature range of the laminated structure 20 thermosetting resin overlap. For example, the synthetic rubber 26 is thermoset at about 180° C. (±20° C.), while the thermosetting resin 20 is also thermoset at about 180° C. (±20° C.).

Explain the effect of synthetic rubber coating.

Although the diaphragm 11 is made of a silicon-based material, it has a poor affinity with the frame 12 including the fiber-reinforced plastic laminated structure 20 and has a problem in adhesion. The interposition of the synthetic rubber 26 between the diaphragm 11 and the laminated structure 20 improves the adhesiveness.

The reusable vacuum bag 10 is assumed to be repeatedly heated and pressurized in the autoclave device. The synthetic rubber 26 protects the laminated structure 20 against repeated heat and pressure from the outside, and reduces deterioration of the laminated structure 20.

Synthetic rubber 26 has elasticity. At the time of evacuation, the seal 13 and the seal 13 are elastically deformed to ensure the sealability.

-Vacuum bag manufacturing method-
The manufacturing method of the vacuum bag 10 is similar to the manufacturing method of the fiber-reinforced plastic laminate as a product. FIG. 4 is an explanatory diagram of a method of manufacturing the vacuum bag 10.

The uncured synthetic rubber sheet 27, the prepreg first layer 21, the prepreg third layer 23, the prepreg second layer 22, the uncured synthetic rubber sheet 28, the adhesive film 29, and the diaphragm 11 are laminated in this order on the jig base 30. The uncured

synthetic rubber sheets

27 and 28 have a size larger than the prepreg layers 21 to 23. The uncured

synthetic rubber sheets

27 and 28 sandwich and include the prepreg layers 21 to 23.

▽Tow (TOW) is arranged on all sides of the laminated structure 20 so that the laminated structure 20 can communicate with the outside of the synthetic rubber coating.

After the stacking is completed, the uncured vacuum bag 10 is bagged together with the jig base 30 by a vacuum bag, conveyed to an autoclave device, and heated and pressed. The vacuum bag used when manufacturing the vacuum bag may be a conventional technique.

At this time, the curing temperature range of the thermosetting resin of the synthetic rubber 26 and the curing temperature range of the laminated structure 20 thermosetting resin overlap (approximately the same). Therefore, the synthetic rubber 26 and the thermosetting resin of the laminated structure 20 are heated by the autoclave device so as to reach the curing temperature or higher.

In the prototype model, the temperature was reduced to 180°C by heating, 0.6 MPa by pressurization, maintained for about 2 hours, and lowered in temperature.

▽At normal temperature, synthetic rubber is semi-cured (commonly called B stage), but it cures at about 180°C. The thermosetting resin of the laminated structure 20 which is not cured at room temperature is also cured at about 180°C. The uncured

synthetic rubber sheets

27 and 28 become the synthetic rubber 26.

The organic solvent gas generated from the thermosetting resin of the laminated structure 20 during heating is discharged outside the synthetic rubber coating through the tow.

The synthetic rubber 26 remains cured and the thermosetting resin of the laminated structure 20 remains cured even when the temperature is lowered or reduced.

The synthetic rubber 26 has a good affinity with the thermosetting resin of the laminated structure 20. Further, the synthetic rubber 26 has a good affinity with the silicon-based material 11.

By a series of heating and pressing, the laminated structure 20, the synthetic rubber 26 and the diaphragm 11 are integrally molded while adhering. The diaphragm 11 is subjected to secondary vulcanization (low-molecular-weight siloxane volatilization treatment) in a series of heating and pressurization.

As described above, the vacuum bag 10 can be integrally molded by using the autoclave device used for manufacturing the product, through a process similar to the manufacturing of the product. That is, it can be easily manufactured.

Especially, when the jig base 30 is existing or has a free curved surface, the ease of manufacturing the vacuum bag 10 becomes remarkable (detailed separately).

Separately mold the seal 13 and adhere it to the lower surface of the frame 12 along the frame 12. Since the frame 12 is covered with the synthetic rubber 26, it easily adheres.

-How to use the vacuum bag (product manufacturing)-

Note that the FRP used in the product will be described below on the assumption that it is a thermosetting resin such as an epoxy resin, but a thermoplastic resin may be used. The thermoplastic resin is softened by heating but solidified by cooling.

FIG. 5 is a diagram for explaining each state in the product manufacturing process. A prototype model of the vacuum bag 10 is shown.

The upper part of Fig. 5 shows the state before construction. The jig base 30 is described.

The middle part of FIG. 5 shows a state in which prepreg sheets are laminated and an uncured fiber-reinforced plastic laminate (uncured laminate) is shaped.

The lower part of FIG. 5 shows a state in which the uncured laminate is covered with the jig base 30 by the vacuum bag 10 and bagging is performed.

After that, it is transferred to the autoclave device and heated and pressed based on the heating and pressing profile (Fig. 6).

FIG. 6 shows an example of a heating/pressurizing profile in the autoclave device. The horizontal axis is time. However, this is an example and the present application is not limited to this.

First, reduce the pressure inside the vacuum bag to -0.1 MPa. Start heating under reduced pressure. Further, pressurization is started while maintaining the reduced pressure. The depressurized state is gradually returned to atmospheric pressure while increasing the pressure. The temperature at this time is about 120 ° C. (± 10 ° C.) (first heating step). Further, the pressure is increased to 0.3 MPa.

Furthermore, the temperature is maintained at about 180°C (±20°C) for several tens of minutes to several hours and maintained for several hours (second heating stage). For example, in the case of an epoxy resin, curing starts at over 160°C. Then, the pressure is reduced to 60° C. or lower again for about 1 hour, and depressurization is started.

This will cure the resin and mold the fiber-reinforced plastic laminate (product). The product is removed from the autoclave together with the jig table 30 and the product is demolded. Demolding also includes removing the vacuum bag 10 from the jig base 30.

The frame 12 of the vacuum bag 10 is lightweight because it is made of fiber reinforced plastic. Therefore, the work of attaching and detaching the vacuum bag 10 is easy and the workability is excellent.

The frame 12 of the vacuum bag 10 is covered with synthetic rubber, and the synthetic rubber 26, together with the seal 13, is appropriately elastically deformed during evacuation. This ensures hermeticity. As a result, the problem of evacuation is reduced. Workability is also excellent in this respect.

Particularly, when the jig base 30 is existing or has a free-form surface, the workability of the vacuum bag 10 is remarkable (detailed separately). In the example of FIG. 1, the frame 12 has a shape corresponding to the free curved surface of the jig base 30.

~ Jig stand ~
The present application is not limited to the case where the jig base 30 already exists or has a free curved surface (may include a new installation, a flat surface, or a simple curved surface), but the jig base 30 may already exist or is free. In the case of having a curved surface, the effect of the present application becomes remarkable.

-A free-form surface is a curved surface that is set by setting some intersections and curvatures in space and interpolating each intersection with a higher-order equation. It is different from a simple curved surface that can be expressed by a simple mathematical formula such as a sphere or a cylindrical surface.

Industrial products such as aircraft and automobiles have free-form surfaces. The jig base used for the prototype model shown in FIG. 5 has a free-form surface. Further, in the example of FIG. 1, the frame 12 has a shape corresponding to the free curved surface of the jig base 30.

-It takes time and effort to design a vacuum bag in detail based on numerical data so as to correspond to a free-form surface. In the case of an existing jig table, the design data of the free-form surface cannot be confirmed, and it may be acquired again by measurement.

Since the vacuum bag of the present application (particularly the frame 12) is manufactured on the existing jig table having a free curved surface, it necessarily follows the free curved surface shape of the existing jig table. Therefore, detailed examination at the design stage is unnecessary, and the product can be manufactured accurately even without design data of the free-form surface.

Also, if the jig base has a free-form surface, there may be a gap between it and the vacuum bag when vacuuming. On the other hand, since the vacuum bag of the present application is manufactured with high accuracy, it adheres to the free curved surface. Further, in the vacuum bag of the present application, the synthetic rubber 26 is also elastically deformed as appropriate. Also in this respect, the sealing property is high.

~Modification~
In the laminated structure 20, instead of the prepreg containing the thermosetting resin, as a modified example, a semi-preg containing a thermoplastic resin that softens at a relatively high temperature (for example, 180 to 220° C.) may be used. The relatively high temperature means a high temperature as compared with the heating profile at the time of manufacturing the product (see FIG. 6). As specific examples, polycarbonate resin PC, nylon 6 resin (polyamide) PA6, polyetherimide resin PEI, polyethylene terephthalate resin PET, polyphenylene sulfide resin PPS, polyetheretherketone resin PEEK, and the like are assumed.

In the manufacturing method of the modified example, the temperature is slightly higher than the heating temperature of the manufacturing method of the embodiment of the present application. In other words, the autoclave is used to heat the thermoplastic resin of the laminated structure 20 to the softening temperature or higher.

In the prototype model, the temperature was reduced to 200°C by heating and 0.6 MPa by pressurization, maintained for about 2 hours, and lowered in temperature and decompressed.

▽At normal temperature, synthetic rubber is semi-cured (commonly called B stage), but it cures at about 180°C. The thermoplastic resin of the laminated structure 20 is softened at, for example, 200 ° C. and solidified by lowering the temperature. By a series of heating and pressing, the laminated structure 20, the synthetic rubber 26, and the diaphragm 11 are integrally molded while being bonded.

The usage method of the modified example is the same as the usage method of the embodiment of the present application. The softening temperature of the thermoplastic resin of the laminated structure 20 is relatively high. In other words, it does not soften at the temperature in the heating and pressurizing profile (FIG. 6) in the product manufacturing process, and maintains the solidified state.

Furthermore, the frame 12 of the present application is covered with synthetic rubber 26 to protect the laminated structure 20.

From these, it is possible to withstand repeated heating and pressurization by the autoclave device. That is, the vacuum bag 10 of the modified example can be reused.

10 Vacuum Bag 11 Diaphragm 12 Frame 13 Seal 20 Laminated Structure 21 Laminated First Layer (UD Layer)
22 Laminated second layer (UD layer)
23 Layered Third Layer (PW Layer)
26 Synthetic Rubber Cover 27 Synthetic Rubber Sheet 28 Synthetic Rubber Sheet 29 Adhesive Film 30 Jig Stand

Claims

A vacuum bag used when vacuuming a fiber sheet laminated on a jig stand,
A diaphragm made of a silicon-based material that covers the fiber sheet,
A frame that supports the diaphragm,
A seal provided along the frame on the lower surface of the frame,
Equipped with
The vacuum bag, wherein the frame has a fiber reinforced plastic.
The part of the frame made of fiber reinforced plastic is coated with non-silicon synthetic rubber.
The vacuum bag according to claim 1, wherein a curing temperature range of the synthetic rubber and a curing temperature range of a resin used for the fiber reinforced plastic overlap each other.
The vacuum bag according to claim 1 or 2, wherein fibers are arranged in one direction of a longitudinal direction of the frame in a portion of the frame made of fiber reinforced plastic.
The part of the frame made of fiber reinforced plastic is
A first layer and a second layer in which fibers are arranged in one direction in the longitudinal direction of the frame;
A third layer which is interposed between the first layer and the second layer and has a fiber in a woven structure,
The vacuum bag according to claim 1 or 2, wherein the vacuum bag is formed by stacking layers.
The jig base has a free-form surface,
The vacuum bag, wherein the frame has a shape corresponding to a free curved surface of the jig base.
A diaphragm made of silicon-based material that covers the fiber sheet for products,
A frame that supports the diaphragm,
A seal provided along the frame on the lower surface of the frame,
Equipped with
The frame is a method of manufacturing a vacuum bag, which is formed by coating a portion made of fiber reinforced plastic with a non-silicon synthetic rubber,
A first non-silicon synthetic rubber sheet, a plurality of fiber sheets for a prepreg-shaped frame, a second non-silicon synthetic rubber sheet, an adhesive film, and a diaphragm are laminated in this order on a jig stand to form a laminate,
A method for manufacturing a vacuum bag, comprising coating with another vacuum bag, heating and pressurizing the above-mentioned laminated body in a vacuum state, and integrally molding.