JP5129931B2 - Vacuum injection molding method for fiber reinforced resin molded products - Google Patents

Description

  The present invention relates to a vacuum injection molding method for fiber-reinforced resin molded products.

  As a lightweight and high-strength material, fiber reinforced plastic (FRP) is attracting attention in various industrial fields. Among them, carbon fiber reinforced plastic is being frequently used due to its excellent mechanical properties. Such fiber reinforced plastics are often formed by a conventional hand lay-up molding method. However, such fiber reinforced plastics are not preferable for manufacturing a relatively large molded product, and cost is high. In recent years, a vacuum injection molding method in which molding is performed in a reduced pressure environment by vacuum suction is being adopted.

The basic technique of this type of vacuum injection molding method is disclosed in, for example, Patent Document 1, in which a fiber layup layer is disposed in a mold and an injection tube for resin distribution is disposed thereon. The bag is covered with a bag film, the periphery is sealed, and an uncured resin is injected into the vacuum-sucked bag film and cured to obtain a molded product.
JP-A-10-504001

  The conventional vacuum injection molding method is a technique suitable for manufacturing a thin-walled molded product among various molding methods. Therefore, when manufacturing a molded product having a certain thickness or a relatively large molded product, In the conventional molding method, it becomes difficult to uniformly impregnate the injected resin into the fiber layup layer for good impregnation.

  Therefore, in such a case, in order to diffuse the injected resin uniformly according to the size and shape of the molding, such as increasing the vacuum pressure or changing the number of injection pipes for resin distribution. It was necessary to repeat the trial and error of this, and to ensure the quality by this, and the place depended on the skill level of the worker.

  In addition, as the thickness and size of the molded product to be molded increases as described above, it is inevitable that the time required for resin injection, vacuum suction, and curing of the injected resin will increase. There was a need to establish a method that could provide

  The present invention has been made in view of the circumstances as described above, and shortens the work time required for molding, in particular, high-quality molding that sufficiently exhibits the advantages of reinforcing fibers in the shortest resin injection time. The purpose is to allow the product to be obtained without depending on the skill level of the operator.

To achieve the above object, the present invention forms a reinforcing fiber base layer to the mold, the resin distribution network to promote the diffusion of the injected resin is laid on top of the reinforcing fiber base layer, the resin on the diffusion net, arranged injection tube for resin injection to the reinforcing fiber base layer, these reinforcing fiber base layer, coating the resin distribution network and the injection tube airtightly on said mold by bag film In addition, a decompression hose connected to a decompression source for decompressing the inside of the bag film is disposed around the reinforcing fiber base layer, and resin is injected in a decompressed environment by vacuum suction, and the reinforcing fiber base A method for vacuum injection molding of a fiber reinforced resin molded article obtained by impregnating a layer with an injection resin, wherein the decompression hose is disposed at a distance from a peripheral portion of the reinforcing fiber base layer, and the reinforcing fiber The base material layer and the resin diffusion net Between has interposed a release sheet to improve the releasing property between the molded article and the bag film, with the release sheet covers the front surface and the side surface of the reinforcing fiber base layer, the releasing the ends of the sheet and arranged as wound on the outer periphery of the vacuum hose has covered also to the outer periphery of the vacuum hose, in the state in which sandwich the end portion of the release sheet between the vacuum hose and the bag film The inside of the bag film is decompressed to form air passages between the edge of the reinforcing fiber base layer and the bag film and between the decompression hose and the bag film .

  According to such an invention, air can be smoothly exhausted by the decompression hose using the air permeability of the release sheet. As a result, the entire bag film can be uniformly vacuum-sucked so that the inside of the molded part can be in a good vacuum state, and the time required for resin injection can be increased without increasing the fluidity of the injected resin and causing impregnation failure. It can be shortened.

  The injected resin is not particularly limited as long as it has a low viscosity, and examples thereof include vinyl ester resins, polyester resins, and epoxy resins. Also, vinyl ester resins are preferred because they have the lowest viscosity and high strength among the current resins.

  According to the vacuum injection molding method of the fiber reinforced resin molded article of the present invention configured as described above, the injection resin is uniformly diffused and impregnated, and the generation of resin non-impregnated parts in the molded article is suppressed, and the efficiency Good quality molded products can be obtained. Further, according to the present invention, the working time required for molding is shortened, and in particular, the time required for resin injection is minimized, and the advantages of reinforcing fibers are sufficiently obtained regardless of the skill level of the operator. It becomes possible to obtain a molded product that has been successfully demonstrated.

  Hereinafter, the best mode for carrying out the vacuum injection molding method of the fiber reinforced resin molded product according to the present invention will be described with reference to examples.

  Example 1 of the vacuum injection molding method for fiber-reinforced resin molded products according to the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic top view schematically illustrating a vacuum injection molding method for a fiber-reinforced resin molded article of Example 1, and FIGS. 2 and 3 are partial cross-sectional views in the molding method.

  In the vacuum injection molding method of the fiber-reinforced resin molded product of the present embodiment, first, one or a plurality of sheet-like reinforcing fiber base materials are alternately laid on the mold 1 and reinforced with an appropriate thickness. The fiber base layer 2 is formed. As the reinforcing fiber base to be laid, for example, a woven fabric or a nonwoven fabric made of fibers such as glass fibers, aramid fibers, and carbon fibers is used.

  Next, a release sheet (peel ply) 3 is laid on the mold 1 on which the reinforcing fiber base layer 2 is formed. This mold release sheet 3 is intended to enhance the mold releasability with a bag film 6 described later that covers the surface side of the molded product after the injected resin is cured, and is non-adhesive to the injected resin. A sheet material made of the material is preferable.

  Next, the resin diffusion net 4 is overlaid on the release sheet 3. The resin diffusion net 4 promotes the diffusion of the injected resin, and uses a mesh-like sheet material having a low resin flow resistance for impregnating the injected resin into the reinforcing fiber base layer 2 evenly.

  The resin diffusion net 4 is preferably smaller than the size of the surface of the reinforcing fiber base layer 2 as appropriate. The resin diffusion net 4 is disposed on the inner side of the four peripheral edges of the reinforcing fiber base layer 2.

  An injection pipe 5 for injecting resin is disposed on the resin diffusion net 4. As the injection tube 5, for example, a porous conduit having a hollow cross section, a conduit formed by spirally winding a long strip member into a tubular shape, or the like is preferable, and is fixed using an adhesive material, a seal tape, or the like.

  At this time, the injection tube 5 is disposed on the resin diffusion net 4 in a certain direction in order to diffuse the injection resin quickly and uniformly in the reinforcing fiber base layer 2. For example, when the reinforcing fiber base layer 2 has a long side and a short side, the injection pipe 5 is arranged in the long side direction so that the resin is reinforced fiber base. The direction flowing into the layer 2 (the direction orthogonal to the tube axis direction of the injection tube 5) is set to the short side direction, and the distance required for inflow and the impregnation time are shortened.

  Subsequently, the mold 1 provided with the release sheet 3, the resin diffusion net 4, and the injection tube 5 is air-tightly covered with the bag film 6. The bag film 6 is not particularly limited as long as it is an airtight and flexible synthetic resin film material. For example, a film material such as nylon, polyester, polyethylene, PVC, or polypropylene can be used.

  Then, the bag film 6 is fixed to the surface of the mold 1 using a sealing material 8 such as an adhesive material or a seal tape at the peripheral edge of the mold 1. Thereby, between the shaping | molding die 1 and the bag film 6 is comprised as an airtight and sealed shaping | molding part.

  Further, in the bag film 6 to be coated in this way, a decompression hose 7 is disposed around the reinforcing fiber base layer 2. The decompression hose 7 is connected to a decompression source such as a vacuum pump, and exhausts air in the molding part to decompress to a predetermined degree of vacuum. The bag film 6 is disposed so as to cover the outside of the decompression hose 7 and keep the inside thereof airtight.

  In injecting the resin, the inside of the bag film 6 (inside the molding part) is depressurized by the decompression hose 7 to be in a vacuum state. In a reduced pressure environment by such vacuum suction, uncured resin is injected from the injection tube 5 and diffused into the molding part. As the injection resin, for example, a low-viscosity vinyl ester resin, an unsaturated polyester resin, an epoxy resin, and the like are preferable. The injected resin is diffused from the injection tube 5 on the upper surface of the resin diffusion net 4 into the molded portion.

  In the present embodiment, the release sheet 3 interposed between the reinforcing fiber base layer 2 and the resin diffusion net 4 can be disposed so that the end of the sheet is at least in contact with the decompression hose 7. preferable.

  In FIG. 2, the size of the release sheet 3 is selected so that the end of the release sheet 3 covers the outer periphery of the decompression hose 7, and the mold 1 is arranged. By doing so, the release sheet 3 is sandwiched between the decompression hose 7 and the bag film 6 around the reinforcing fiber base layer 2.

  Naturally, the bag film 6 does not have air permeability, so if it is around the decompression hose 7, the air flow is likely to be hindered. For this reason, for example, when the release sheet 3 is made approximately the same size as the reinforcing fiber base layer 2 and laminated on the surface of the reinforcing fiber base layer 2, or the thickness of the reinforcing fiber base layer 2 is increased. If the release sheet 3 is formed so as not to be in contact with the decompression hose 7, such as when it is disposed so as to cover up to the side surface (thickness) of the reinforcing fiber base layer 2, the bag film 6 becomes the decompression hose 7 Will be in close contact.

  In contrast, by providing the release sheet 3 between the decompression hose 7 and the bag film 6, air can be smoothly exhausted by the decompression hose 7 using the air permeability of the release sheet 3. Can be performed.

  Therefore, when the release sheet 3 is disposed so as to be wound around the outer periphery of the decompression hose 7 as illustrated in FIG. 2, the mold 1, the edge of the reinforcing fiber base layer 2, the decompression hose 7, Air passages are formed between the two. Thereby, the vacuum suction in a shaping | molding part can be made easy and can be pressure-reduced efficiently.

  Further, as illustrated in FIG. 3, the end portion of the release sheet 3 may be disposed so as to be laid under the decompression hose 7. In any case, it is possible to uniformly vacuum-suck the entire molded portion, thereby improving the fluidity of the injected resin and shortening the time required for resin injection.

  After the resin is injected, the resin diffused in the molded portion is impregnated into the reinforcing fiber base layer 2 by the vacuum suction. Such vacuum suction is preferably continued until at least the resin impregnation of the reinforcing fiber base is completed. Then, the injected resin is cured by predetermined heating or cooling to room temperature by being left standing. When the injected resin is cured in the molded part, the reinforcing fiber base layer and the resin are integrated to obtain a molded product. After the solidified molded product is removed from the mold 1, the edge of the molded product can be trimmed to obtain a desired molded product.

Next, a reference example of the present invention will be described with reference to FIGS. In the following description, the same components as those in the first embodiment are not described, and the same reference numerals are used to omit the detailed description.

FIG. 4 is a top view schematic diagram schematically showing a vacuum injection molding method for a fiber-reinforced resin molded article of a reference example .

  As shown in FIG. 4, a reinforcing fiber base layer 2 is formed on the mold 1, and a decompression hose 7 connected to a decompression source (vacuum pump) (not shown) is provided around the reinforcing fiber base layer 2. Arrange. Further, a release sheet (3) is disposed on the reinforcing fiber base layer 2, and a resin diffusion net 4 that promotes diffusion of the injected resin is laid on the release sheet (3). An injection pipe 5 for injecting resin into the reinforcing fiber base layer 2 is disposed on the resin diffusion net 4.

  Further, the reinforcing fiber base layer 2, the release sheet, the resin diffusion net 4 and the injection tube 5 are hermetically covered on the mold 1 with the bag film 6. In injecting the resin, the inside of the bag film 6 (inside the molding part) is depressurized by the decompression hose 7 to be in a vacuum state. Then, in a reduced pressure environment by such vacuum suction, uncured resin is injected from the injection tube 5 and diffused into the molding part.

Here, vacuum suction is performed so that the pressure for depressurizing the inside of the molded part is 0.035 MPa or more. FIG. 5 is a comparison table of the evaluation of the impregnation state of the injected resin and the time required for resin injection when the pressure in the molding part during vacuum suction is changed, and FIG. 6 is a table comparing the time required for resin injection and molding. It is a graph which shows the relationship with the pressure in a part.

  Evaluation of the time required for these resin injections is performed using a reinforcing fiber base layer 2 constituted by laminating a glass roving cloth and a glass chop strand mat, and the thickness of the reinforcing fiber base layer 2 is 10 mm. The measurement was carried out using a common shape having a side W of 346 mm square. The glass roving cloth is a fiber base material formed into a woven fabric using a roving formed by aligning glass strands obtained by bundling glass fiber filaments as a weft. Moreover, the glass chop strand mat is formed by cutting glass strands obtained by focusing glass fiber filaments into a predetermined length and orienting them in the plane.

  As the decompression hose 7 disposed around the reinforcing fiber base layer 2, one having a tube diameter of 8 mm was selected. Further, one injection tube 5 is arranged at the center of the resin diffusion net 4 at a position where the distances to both side edges of the resin diffusion net 4 parallel to the arrangement direction of the injection tube 5 are equal.

  As the injection resin, a vinyl ester resin containing 1% of a curing agent and 0.80% of a curing accelerator (cobalt naphthenate) was used. The room temperature was 23 ° C., and the temperature of the injected resin was 20 ° C.

As shown in FIGS. 5 and 6, when the pressure for reducing the pressure inside the molded part is 0.02 MPa and 0.03 MPa, the impregnation state of the injected resin into the reinforcing fiber base layer 2 is poor due to insufficient pressure reduction. An unimpregnated site was generated. Further, when the pressure was 0.02 MPa, the impregnation of the injected resin did not proceed and the resin injection could not be completed, and at 0.03 MPa, the resin injection took 45 minutes.

On the other hand, when the pressure for depressurizing the inside of the molded part was 0.04 MPa and 0.05 MPa, the impregnation state of the injected resin was good, and the time required for the resin injection was 25 minutes or less. Furthermore, when the pressure for depressurizing the inside of the molded part was 0.06 MPa, it was in a good impregnation state and the time required for resin injection could be 19 minutes, and the resin injection could be completed in the shortest time.

Even when the pressure was set to vacuum molding portion than 0.07 MPa, but preferably the time required for the impregnation conditions and the resin injection injection resin results were obtained, the vacuum pump of the resin by vacuum suction for vacuum pressure is greater There was a possibility of sucking up to the vicinity, and it was confirmed that the optimum pressure environment for reducing the pressure inside the molded part was 0.06 MPa.

Therefore, it is required to manage the pressure for depressurizing the inside of the molded part within a range of 0.035 to 0.06 Pa. Thereby, a high-quality molded product can be obtained efficiently in a short time.

Next, another reference example of the present invention will be described with reference to FIGS. In the following description, the same components as those in the first embodiment are not described repeatedly, and the same reference numerals are used to omit the detailed description.

FIG. 7 is a schematic top view schematically showing a vacuum injection molding method for a fiber-reinforced resin molded article of a reference example .

  As shown in FIG. 7, a reinforcing fiber base layer 2 is formed on the mold 1, and a decompression hose 7 connected to a decompression source (vacuum pump) is reinforced around the reinforcing fiber base layer 2. It arrange | positions maintaining the distance L with the edge part of the fiber base material layer 2. FIG. Furthermore, on the upper layer of the reinforcing fiber base layer 2, a release sheet (3) and a resin diffusion net 4 for promoting diffusion of the injected resin are laid in order. An injection tube 5 for injecting resin into the reinforcing fiber base layer 2 is disposed on the resin diffusion net 4.

  Further, the reinforcing fiber base layer 2, the resin diffusion net 4 and the injection tube 5 are airtightly covered on the mold 1 with the bag film 6. In injecting the resin, the inside of the bag film 6 (inside the molding part) is depressurized by the decompression hose 7 to be in a vacuum state. Then, in a reduced pressure environment by such vacuum suction, uncured resin is injected from the injection tube 5 and diffused into the molding part.

  In this embodiment, the distance L from the edge of the reinforcing fiber base layer 2 on the mold 1 to the decompression hose 7 is set to 50 mm or more.

  FIG. 8 is a comparison table of the evaluation of the impregnation state of the injected resin and the time required for resin injection when the distance L from the edge of the reinforcing fiber base layer 2 to the decompression hose 7 is changed from 0 mm to 150 mm. FIG. 9 is a graph showing the relationship between the time required for resin injection and the distance from the edge of the reinforcing fiber base layer 2 to the decompression hose 7.

  Evaluation of the time required for these resin injections was performed using a reinforcing fiber base layer 2 formed by laminating a glass roving cloth and a glass chop strand mat, and the thickness of the reinforcing fiber base layer 2 was 10 mm. The size W of one side of the base material layer 2 was made into a square shape of 346 mm, and all of them were carried out in common. The glass roving cloth is a fiber base material formed into a woven fabric using a roving formed by aligning glass strands obtained by bundling glass fiber filaments as a weft. Moreover, the glass chop strand mat is formed by cutting glass strands obtained by focusing glass fiber filaments into a predetermined length and orienting them in the plane.

  As the decompression hose 7 disposed around the reinforcing fiber base layer 2, one having a tube diameter of 8 mm was selected. Further, one injection tube 5 is arranged at the center of the resin diffusion net 4 at a position where the distances to both side edges of the resin diffusion net 4 parallel to the arrangement direction of the injection tube 5 are equal.

  As the injection resin, a vinyl ester resin containing 1% of a curing agent and 0.80% of a curing accelerator (cobalt naphthenate) was used. The room temperature was 24 ° C., and the temperature of the injected resin was 22 ° C.

  As shown in FIGS. 8 and 9, when both the reinforcing fiber base layer 2 and the reduced pressure hose 7 are in contact with each other, the impregnated state of the injected resin into the reinforcing fiber base layer 2 is poor, Impregnation sites were generated. Further, when the distance L from the edge of the reinforcing fiber base layer 2 to the decompression hose 7 was 20 mm, an unimpregnated portion of the injected resin was produced in part, and it took 50 minutes for the resin injection.

  On the other hand, when the distance L from the edge of the reinforcing fiber base layer 2 to the decompression hose 7 was 40 mm, the resin impregnation state was good although the resin injection took 48 minutes. When the distance L is further increased to 60 mm, the resin impregnation state is good and the time required for the resin injection is shortened to 35 minutes. When the distance L is 80 mm, the resin injection is completed in 30 minutes. I was able to.

  Further, when the distance L from the edge of the reinforcing fiber base layer 2 to the decompression hose 7 was further increased to more than 80 mm, a good impregnation state was obtained and the injection time was shortened, but the distance L was large. In proportion to this, the mold is also enlarged, so it is practical to set the distance L to about 100 mm.

  Therefore, it is required to manage the distance L from the edge portion of the reinforcing fiber base layer 2 to the reduced pressure hose 7 in the range of 50 mm to 100 mm, and the optimum distance is 80 mm, thereby efficiently in a short time, A high-quality molded product can be obtained.

  As described above, by taking the vacuum injection molding method according to the present invention, a good impregnation state of the injected resin can be obtained while managing the time required for the resin injection to be short, regardless of the skill level of the operator. A high-quality fiber-reinforced resin molded product can be formed.

  The present invention can be suitably used to mold a high-quality fiber-reinforced resin molded product in a short time.

It is a top view schematic diagram which shows Example 1 of the vacuum injection molding method of the fiber reinforced resin molded product which concerns on this invention. 3 is a partial cross-sectional view schematically showing the molding method of Example 1. FIG. 3 is a partial cross-sectional view schematically showing a reference example of the forming method of Example 1. FIG. It is a top view schematic diagram which shows the reference example of the vacuum injection molding method of the fiber reinforced resin molded product which concerns on this invention. In the said reference example, it is a comparison table | surface of the time required for evaluation of the impregnation state of injection | pouring resin when changing the pressure in the molding part at the time of vacuum suction, and resin injection | pouring. In the said reference example, it is a graph which shows the relationship between the time required for resin injection | pouring, and the pressure in a molding part. It is a top view schematic diagram which shows the other reference example of the vacuum injection molding method of the fiber reinforced resin molding which concerns on this invention. In the said reference example, it is a comparison table | surface of the time required for evaluation of the impregnation state of injection | pouring resin when changing the distance from the edge part of a reinforced fiber base material layer to a pressure reduction hose, and resin injection | pouring. In the said reference example, it is a graph which shows the relationship between the time required for resin injection | pouring, and the distance from the edge part of a reinforced fiber base material layer to a decompression hose.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 2 Reinforcement fiber base layer 3 Release sheet 4 Resin diffusion net 5 Injection pipe 6 Bag film 7 Decompression hose 8 Sealing material

Claims (1)

Forming a reinforcing fiber base layer on the mold,
Laying a resin diffusion net that promotes the diffusion of the injected resin on the upper layer of the reinforcing fiber base layer,
An injection tube for injecting resin into the reinforcing fiber base layer is disposed on the resin diffusion net ,
The reinforcing fiber base layer, the resin diffusion net, and the injection tube are hermetically covered on the mold by a bag film, and a decompression hose connected to a decompression source for decompressing the inside of the bag film is connected to the reinforcing fiber base. Arranged around the layer,
A vacuum injection molding method of a fiber reinforced resin molded article obtained by injecting a resin under a reduced pressure environment by vacuum suction and impregnating the reinforcing fiber base layer with an injection resin,
The decompression hose is disposed at a distance from the edge of the reinforcing fiber base layer,
Between the reinforcing fiber base layer and the resin diffusion net, a release sheet that enhances the release properties of the molded product and the bag film is interposed,
With this release sheet , the surface and side surfaces of the reinforcing fiber base layer are covered, and the end of the release sheet is disposed so as to be wrapped around the outer periphery of the decompression hose to cover the outer periphery of the decompression hose. Yes,
The inside of the bag film is depressurized with the end portion of the release sheet being sandwiched between the decompression hose and the bag film, and between the marginal portion of the reinforcing fiber base layer and the bag film and the decompression hose. A vacuum injection molding method for a fiber-reinforced resin molded product , wherein an air passage is formed between the bag and the bag film .

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