JP6625300B1 - Vacuum bag and method of manufacturing vacuum bag - Google Patents

Abstract

Provide a reusable vacuum bag that is lightweight, has excellent workability, and is easy to manufacture. The vacuum bag 10 includes a diaphragm 11, a frame 12, and a seal 13. The frame 12 is made of a fiber-reinforced plastic laminated structure 20. The fiber reinforced plastic laminate structure 20 is covered with a thermosetting non-silicone synthetic rubber 26. The curing temperature range of the synthetic rubber 26 and the curing temperature range of the thermosetting resin of the laminated structure 20 overlap. As a result, the synthetic rubber 26 and the laminated structure 20 are integrally formed. In this step, the synthetic rubber 16 is bonded to the silicon-based diaphragm 11. That is, the vacuum bag 10 can be easily manufactured by integral molding. In particular, when the jig base 30 has a free surface, the effect of facilitating manufacture becomes remarkable.

Description

  The present invention relates to a vacuum bag used when heating and pressing a fiber-reinforced plastic laminate.

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

  An example of a method for forming a fiber-reinforced plastic laminate will be briefly described. The prepreg sheet laminate 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 in a sheet shape.

  As the thermosetting resin, unsaturated polyester, epoxy resin, phenol resin and the like are used.

  Further, the shaped fiber-reinforced plastic laminate is bagged together with the jig stand, evacuated, conveyed to an autoclave, and heated and pressed. As a result, the resin cures and a fiber-reinforced plastic laminate is formed. Each time, the product is released.

  Note that a thermoplastic resin such as a polyamide resin or a 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). As the vacuum bag, a polymer film such as nylon or a diaphragm made of a silicon-based material is used.

Japanese Patent Publication No. Hei 8-506534

  Generally, the vacuum bag is discarded every time the heating and pressing molding process is completed, and a new vacuum bag is used in the next heating and pressing molding process. As a result, it is reflected in product manufacturing costs. Also, disposal costs are reflected in product manufacturing costs.

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

  Generally, members such as aircraft and automobiles are large, and when the vacuum bag is enlarged accordingly, the weight of the metal frame also increases. As a result, workability such as attachment and detachment of the vacuum bag is reduced. That is, there is a problem relating to weight and workability.

  In addition, after manufacturing a metal frame, a plurality of steps such as bonding a diaphragm to the metal frame are performed, and the manufacturing process is complicated.

  Incidentally, members such as aircraft and automobiles have complicated shapes such as free-form surfaces. 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. It is possible to form a complicated frame shape such as a free-form surface by processing metal, but processing is not easy. The manufacturing process is further complicated.

  When the vacuum bag manufacturing process becomes complicated, it affects the product cost. As described above, there is a problem relating to manufacturability.

  An object of the present invention is to solve the above-mentioned problems, and to provide a reusable vacuum bag that is lightweight, has excellent workability, and is easy to manufacture.

  The present invention that solves the above-mentioned problems is a vacuum bag used when vacuuming a fiber sheet laminated on a jig stand. A diaphragm made of a silicon-based material covering the fiber sheet; a frame supporting the diaphragm; and a seal provided along a frame on a lower surface of the frame, wherein the frame includes fiber-reinforced plastic.

  The frame is lightweight due to having fiber reinforced plastic. As a result, the work of attaching and detaching the vacuum bag is easy and the workability is excellent.

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

  Non-silicon-based synthetic rubber has a high affinity for fiber-reinforced plastic. By heat and pressure molding, the fiber reinforced plastic of the frame and the synthetic rubber are integrally molded. In the same step, the synthetic rubber and the diaphragm are bonded. That is, it is easy to manufacture.

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

  Thereby, the straightness of the fiber can oppose 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 in the frame longitudinal direction, and the first layer and the second layer, The third layer, in which the fibers are woven, is laminated.

  With such a sandwich structure, the straightness of the fiber opposes external force, and the woven structure suppresses generation of distortion and cracks.

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

  When the jig base has a free surface, the effect of facilitating manufacture becomes significant.

  The present invention for solving the above problems is a method for manufacturing a vacuum bag. 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 provided along a frame on a lower surface of the frame, wherein the frame is fiber-reinforced. It is formed by covering a plastic part with a non-silicon-based synthetic rubber. On a jig table, a first non-silicon-based synthetic rubber sheet, a plurality of fiber sheets for a prepreg-shaped frame, a second non-silicon-based synthetic rubber sheet, an adhesive film, and a diaphragm are laminated in this order to form a laminate, The laminate is covered with another vacuum bag, and the laminate is heated and pressurized in a vacuum state to be integrally molded.

  The reusable vacuum bag according to the present invention can be easily manufactured by integral molding using an autoclave apparatus 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 excellent in workability.

  The reusable vacuum bag according to the present invention is easy to manufacture by integral molding.

Schematic diagram of vacuum bag Vacuum bag details Detailed configuration diagram of laminated structure Illustration of vacuum bag manufacturing method Illustration of how to use the vacuum bag Heating and pressing 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 includes a diaphragm 11, a frame 12 (partially sectioned), and a seal 13 (see FIG. 2).

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

  The frame 12 is adhered to the periphery of the diaphragm 11 and supports the diaphragm 11. Details will be described later.

  The seal 13 is provided on the lower surface of the frame 12 along the frame 12. At the time of evacuation, the sealing between the surface of the jig stand 30 and the vacuum bag 10 is ensured by elastic deformation.

  The diaphragm 11 and the seal 13 may be the same as those of the prior art. 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 molding them under heat and pressure.

  FIG. 3 is a schematic diagram 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 the layers are formed of one prepreg sheet and a case where a plurality of prepreg sheets are stacked and formed.

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

  Since the first layer 21 and the second layer 22 do not have a woven structure, the fibers can maximize linearity against external force. In the case of a woven structure, the fibers move up and down in the vertical direction, so that the straightness cannot be exhibited. The opposing force may be dispersed.

  In the third layer 23, the fibers are arranged in the vertical and horizontal directions and have a woven structure, for example, a 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. In addition, a plain weave is mentioned as a typical example of the woven structure, but the present invention is not limited to this.

  By interposing a woven structure, distortion in the first layer 21 and the second layer 22 is suppressed, and cracks are suppressed.

  Note that 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.

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

~ Synthetic rubber coating ~
The portion 20 of the frame 12 made of fiber reinforced plastic is preferably covered with a thermosetting non-silicone synthetic rubber 26. However, the non-silicon-based synthetic rubber may contain a trace amount of a silicon component to such an extent that physical properties are not affected.

  Regarding the curing temperature, it is preferable to thermally cure in an autoclave device used for product production. For example, it is preferable to perform thermosetting 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 was used. The air pad rubber is an uncured non-silicone synthetic rubber, which is heated to 176 ° C., pressurized to 0.6 MPa, cured in about 2 hours, and has heat resistance of 204 ° C.

  The synthetic rubbers having high heat resistance include acrylic rubbers ACM and ANM, ethylene vinyl acetate rubber EVA, epichlorohydrin rubbers CO and ECO, and the like.

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

  The effect of the synthetic rubber coating will be described.

  The diaphragm 11 is made of a silicon-based material, but does not have a good affinity for the frame 12 including the fiber-reinforced plastic laminated structure 20, and has a problem in adhesiveness. Since the synthetic rubber 26 is interposed between the diaphragm 11 and the laminated structure 20, the adhesiveness is improved.

  It is assumed that the reusable vacuum bag 10 is repeatedly heated and pressurized in an autoclave device. The synthetic rubber 26 protects the laminated structure 20 against repeated heating and pressing from the outside, and reduces the deterioration of the laminated structure 20.

  The synthetic rubber 26 has elasticity. At the time of evacuation, the sealing property is ensured by appropriate elastic deformation together with the seal 13.

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

  An uncured synthetic rubber sheet 27, a prepreg first layer 21, a prepreg third layer 23, a prepreg second layer 22, an uncured synthetic rubber sheet 28, an adhesive film 29, and the diaphragm 11 are laminated in this order on the jig table 30. The uncured synthetic rubber sheets 27 and 28 have dimensions slightly 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.

  Tows (TOW) are 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 lamination is completed, the uncured vacuum bag 10 is bagged with the jig table 30 by a vacuum bag, transported to an autoclave device, and heated and pressurized. The vacuum bag used in the production of the vacuum bag may be a conventional one.

  At this time, the curing temperature range of the thermosetting resin of the synthetic rubber 26 and the curing temperature range of the thermosetting resin of the laminated structure 20 overlap (approximately the same). Therefore, heating is performed by an autoclave device so that the temperature becomes equal to or higher than the curing temperature of the synthetic rubber 26 and the thermosetting resin of the laminated structure 20.

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

  At room temperature, synthetic rubber is semi-cured (commonly referred to as B stage), but cures at about 180 ° C. The thermosetting resin of the laminate structure 20 that has not been 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 at the time of heating is discharged outside the synthetic rubber coating via the tow.

  Even when the temperature is reduced and the pressure is reduced, the synthetic rubber 26 remains cured, and the thermosetting resin of the laminated structure 20 remains cured.

  The synthetic rubber 26 has a good affinity for the thermosetting resin of the laminated structure 20. The synthetic rubber 26 also has a good affinity for 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 formed while being adhered. In a series of heating and pressing, the diaphragm 11 is subjected to secondary vulcanization (low molecular weight siloxane volatilization treatment).

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

  In particular, when the jig stand 30 is existing or has a free-form surface, the ease of manufacturing the vacuum bag 10 becomes remarkable (detailed separately).

  The seal 13 is separately formed and adhered to the lower surface of the frame 12 along the frame 12. Since the frame 12 is covered with the synthetic rubber 26, it is easily adhered.

  ~ How to use vacuum bag (product manufacturing) ~

  The following description is based on the premise that the FRP used for the product 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 illustrating each state in a product manufacturing process. A prototype model of the vacuum bag 10 is shown.

  The upper part of FIG. 5 shows a state before construction. A jig stand 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 formed.

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

  After that, it is conveyed to an autoclave device and heated and pressed based on a heating and pressing profile (FIG. 6).

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

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

  Further, the temperature is raised to about 180 ° C. (± 20 ° C.) over 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 160 ° C. or higher. Thereafter, it is cooled down to 60 ° C. or lower again over about one hour, and depressurization is started.

  Thereby, the resin is cured, and a fiber-reinforced plastic laminate (product) is formed. The product is carried out of the autoclave together with the jig stand 30, and the product is released. Removal includes removing the vacuum bag 10 from the jig stand 30.

  Since the frame 12 of the vacuum bag 10 is made of fiber reinforced plastic, it is lightweight. 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 coated with a synthetic rubber, and the synthetic rubber 26 is elastically deformed with the seal 13 at the time of evacuation. This ensures a tight seal. As a result, the problem of evacuation is reduced. Also in this point, workability is excellent.

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

~ Jig stand ~
The present application is not limited to the case where the jig table 30 is existing or has a free-form surface (may include a newly-installed, flat, or simple curved surface). In the case of having a curved surface, the effect of the present invention is remarkable.

  A free-form surface is a surface that is expressed 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 represented by a simple mathematical expression 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. In the example of FIG. 1, the frame 12 has a shape corresponding to the free-form surface of the jig stand 30.

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

  Since the vacuum bag of the present application (particularly, the frame 12) is manufactured on an existing jig table having a free-form surface, the vacuum bag necessarily follows the free-form surface shape of the existing jig table. Therefore, a detailed study at the design stage is not required, and the device can be manufactured with high accuracy without design data of a free-form surface.

  When the jig base has a free-form surface, a gap may be formed between the jig base and the vacuum bag during evacuation. On the other hand, since the vacuum bag of the present application is manufactured with high accuracy, it is in close contact with a free-form surface. In the vacuum bag of the present invention, the synthetic rubber 26 is also elastically deformed as appropriate. Also in this respect, the sealing property is high.

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

  In the manufacturing method of the modified example, the heating temperature is slightly higher than the heating temperature of the manufacturing method of the embodiment of the present application. That is, heating is performed by an autoclave apparatus so that the temperature is equal to or higher than the softening temperature of the thermoplastic resin of the laminated structure 20.

  In the prototype model, the temperature was increased to 200 ° C. by heating, to 0.6 MPa by pressing, maintained for about 2 hours, and the temperature was reduced and reduced.

  At room temperature, synthetic rubber is semi-cured (commonly referred to as B stage), but 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 formed while being adhered.

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

  The usage of the modified example is the same as the usage 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 a solidified state.

  Further, the frame 12 of the present application is covered with a 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.

Reference Signs List 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 Laminated third layer (PW layer)
26 Synthetic rubber coating 27 Synthetic rubber sheet 28 Synthetic rubber sheet 29 Adhesive film 30 Jig stand

Claims (5)

A vacuum bag used when vacuuming the fiber sheet laminated on the jig table,
A diaphragm made of a silicon-based material covering the fiber sheet,
A frame supporting the diaphragm,
A seal provided along the frame on the lower surface of the frame,
With
The frame has a fiber reinforced plastic,
At least a portion of the frame made of fiber-reinforced plastic, which faces the diaphragm, is covered with a non-silicon-based synthetic rubber,
A vacuum bag wherein a curing temperature range of the synthetic rubber and a curing temperature range of a resin used for the fiber reinforced plastic overlap . 2. The vacuum bag according to claim 1, wherein, in a portion of the frame made of fiber reinforced plastic, fibers are arranged in one direction in a frame longitudinal direction. 3. The portion made of fiber reinforced plastic of the frame,
A first layer and a second layer in which fibers are arranged in one direction in the frame longitudinal direction,
A third layer interposed between the first layer and the second layer, wherein the fiber has a woven structure;
The vacuum bag according to claim 1 , wherein the vacuum bag is formed by being laminated. The jig stand has a free-form surface,
The vacuum bag according to any one of claims 1 to 3 , wherein the frame has a shape corresponding to a free-form surface of the jig base. A diaphragm made of a silicon-based material covering a fiber sheet for a product,
A frame supporting the diaphragm,
A seal provided along the frame on the lower surface of the frame,
With
The frame is a method of manufacturing a vacuum bag formed by covering a portion made of fiber-reinforced plastic with a non-silicon-based synthetic rubber,
On a jig table, 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 to form a laminate,
A method for manufacturing a vacuum bag, wherein the laminate is heated and pressurized in a vacuum state by being covered with another vacuum bag and integrally molded.

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