Bagging sheet for VaRTM molding and VaRTM molding method

Abstract

To provide a bagging sheet for vacuum assisted resin transfer molding that prevents occurrence of gaps between the bagging sheet and a tube, effectively evacuates the inside of the bagging sheet, and improves work efficiency, and a vacuum assisted resin transfer molding method.SOLUTION: There is provided a bagging sheet 100 for vacuum assisted resin transfer molding. The bagging sheet is used for sealing a repair space in vacuum assisted resin transfer molding. Lines 110 and 120 are attached to the bagging sheet 100. The lines are used as an index, edges of the bagging sheet are folded in the order of valley fold, mountain fold, and valley fold, and a sheet end portion can be formed at an installation position of a vacuum suction tube or a resin injection tube (a vacuum suction tube 30 or a resin injection tube 40).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bagging sheet for VaRTM molding that seals a repair space in VaRTM molding, and a VaRTM molding method using the same. [Background technology]

[0002] In recent years, VaRTM (Vacuum assisted Resin Transfer Molding) has been used as a technology for repairing structures. In VaRTM, reinforcing fiber sheets are layered over the area of ​​the structure to be repaired, and the multiple layers of reinforcing fiber sheets are covered with a film. After that, the interior is depressurized with a vacuum pump, and resin is injected to integrate the FRP (fiber reinforced plastic) with the structure, thereby repairing the structure.

[0003] For example, Patent Document 1 discloses an adhesive structure for attaching FRP material to a structure. In the adhesive structure of Patent Document 1, an adhesive layer formed of a fiber-based base material and a resin is interposed between the structure and the FRP material, and the adhesive layer protrudes from the edge of the FRP material. According to Patent Document 1, this configuration allows for a sufficiently high adhesive strength to be exerted between the structure to be repaired or reinforced and the FRP material used as a reinforcing material, ensuring that the repair and reinforcement performance of the FRP material can be achieved in the structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 199032 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, when repairing a structure using VaRTM molding, a sealant is laid around the perimeter of the repair area, and a reinforcing fiber sheet or other material is placed within the enclosed sealant area. A tube connected to a vacuum suction pump or resin pot is then placed inside the bagging sheet. The area is then covered with a film (hereafter referred to as the bagging sheet), and the film is sealed tightly to the structure with a sealant. If a gap forms between the bagging sheet and the tube, the bagging sheet cannot be vacuumed and the sealed state cannot be maintained, resulting in reduced reinforcement quality and reduced work efficiency, such as prolonged pump operation.

[0006] Furthermore, the reinforcing fiber sheets are thick, and the surface of the steel reinforcement becomes uneven because the tubes rest on them. Therefore, the size of the bagging sheet is made larger than the surface area to be evacuated so that the tension generated in the bagging sheet during evacuation and the bagging sheet can conform to the surface irregularities are alleviated. In other words, the side length of the bagging sheet is made larger than that of the reinforced area. To achieve a sealed state, the side length is adjusted by creating several folds in part of the bagging sheet's side length to match the side length of the reinforced area. However, if gaps are created in these adjusted areas, a vacuum cannot be created and the sealed state cannot be maintained. Furthermore, if the side length is inappropriate, the bagging sheet will be pulled by the tension generated during evacuation, causing the sealing material placed between the bagging sheet and the structure to peel off slightly, making it impossible to maintain the sealed state.

[0007] In view of these problems, the present invention aims to provide a bagging sheet for VaRTM molding and a VaRTM molding method that can prevent gaps from occurring between the bagging sheet and the tube or in the bagging sheet side length adjustment areas, efficiently create a vacuum inside the bagging sheet, improve work efficiency, and maintain the quality of the FRP material. [Means for solving the problem]

[0008] To solve the above problems, a typical configuration of a bagging sheet for VaRTM molding according to the present invention is a bagging sheet that seals a repair space during VaRTM molding, characterized in that the bagging sheet has lines on it, and by using the lines as guides to fold the edges of the bagging sheet in the order of valley fold, mountain fold, and valley fold again, it is possible to form ears at the installation positions of tubes for vacuum suction or resin injection. Note that the "ears" may also be called "tabs."

[0009] In the above configuration, the bagging sheet is folded to form tabs. Then, the tubes are inserted into these tabs. Sealant tape is wrapped around the positions of the tubes corresponding to the tabs to increase the thickness of the sealant tape. This prevents gaps from occurring between the bagging sheet and the tubes, and makes it possible to seal the inside of the bagging sheet. Therefore, the inside of the bagging sheet can be efficiently evacuated, improving work efficiency.

[0010] In particular, the bagging sheet of the present invention has lines that indicate the positions where the selvages will be formed, and in turn, the positions where the tubes will be installed. By forming lines on the bagging sheet that serve as indicators for the selvages, the worker can easily grasp the positions where the selvages will be formed.

[0011] The lines are preferably drawn on at least two of the three folds: the valley fold, the mountain fold, and the valley fold. In this way, if lines are drawn on at least two of the three folds, the above-mentioned effects can be obtained.

[0012] Furthermore, by placing the sealant tape on the lines of the bagging sheet in advance, workability on site can be improved.

[0013] To solve the above problems, a typical configuration of the VaRTM molding method according to the present invention is characterized by using the above-mentioned VaRTM molding bagging sheet. The components and their explanations corresponding to the technical concept of the above-mentioned VaRTM molding bagging sheet can also be applied to the VaRTM molding method. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a bagging sheet for VaRTM molding and a VaRTM molding method that can prevent gaps from occurring between the bagging sheet and the tube or at the ears of the bagging sheet, efficiently create a vacuum inside the bagging sheet, and improve work efficiency. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram illustrating a VaRTM molding method according to an embodiment of the present invention. FIG. [Figure 2] 1A and 1B are diagrams illustrating a bagging sheet according to an embodiment of the present invention. [Figure 3] FIG. 10 is a diagram illustrating the attachment of a bagging sheet to a steel pipe. DETAILED DESCRIPTION OF THE INVENTION

[0016] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0017] FIG. 1 is a schematic diagram illustrating the VaRTM forming method of this embodiment. In this embodiment, the procedure of the VaRTM forming method will be explained first, and then the bagging sheet 100 will be described in detail. In this embodiment, the repair target is a steel pipe 10 shown in FIG. 1 as an example. However, the repair target is not limited to this, and the VaRTM forming method of this embodiment can also be applied to the repair of other structures.

[0018] As shown in FIG. 1 , corrosion occurs in a steel pipe 10 due to deterioration over time, and as the corrosion progresses, a hole may develop (hereinafter, the hole will be referred to as an opening 12). When repairing the opening 12 of a steel pipe 10 using the VaRTM forming method of this embodiment, the area around the opening 12 is first cleaned and the surface is adjusted. Then, a plastic film is adhered to the area around the opening 12 to seal the opening 12. A sealant tape 130 is placed around the area to be covered with a bagging sheet 100 and evacuated. An adhesive layer sheet 20 is attached on top of the plastic film, and then a reinforcing fiber sheet 22 is laminated on top of the adhesive layer sheet 20. Here, the bagging sheet 100 may be used as the plastic film, but a film with a thickness of about 50 μm or more that will not deform in a vacuum is preferred.

[0019] Next, a peel ply 24 is laid on the reinforcing fiber sheet 22. For example, a glass cloth coated with a fluororesin can be suitably used as the peel ply 24. By laying the peel ply 24 on the reinforcing fiber sheet 22 in this manner, a sheet laminated on the peel ply 24 can be easily peeled off from the reinforcing fiber sheet 22 later. Note that if a resin diffusion sheet 26, which will be described next, is to be left in place, the installation of the peel ply 24 can be omitted.

[0020] Next, a resin diffusion sheet 26 is laminated on the peel ply 24. The resin diffusion sheet 26 is a net-like sheet provided to allow the resin, which will be described later, to flow appropriately onto the surface of the reinforcing fiber sheet 22. After the resin diffusion sheet 26 is laminated, a vacuum suction tube 30 and a resin injection tube 40 are placed on top of it. The vacuum suction tube 30 is connected to a suction pump (not shown). The resin injection tube 40 is connected to a resin tank 42 in which resin is stored.

[0021] After the vacuum suction tube 30 and the resin injection tube 40 are installed, the bagging sheet 100 of this embodiment is placed on top of them. After the periphery of the bagging sheet 100 is sealed, the air inside the bagging sheet 100 is sucked out using a suction pump. This creates a vacuum inside the bagging sheet 100, and the resin is sucked into the bagging sheet 100. If there are gaps between the bagging sheet 100 and the vacuum suction tube 30 and the resin injection tube 40 at the insertion points, the inside of the bagging sheet 100 cannot be quickly evacuated. Therefore, to prevent the occurrence of such gaps, the bagging sheet 100 is used in the VaRTM molding method of this embodiment.

[0022] Fig. 2 is a diagram illustrating the bagging sheet 100 of this embodiment. Fig. 2(a) is a plan view of the bagging sheet 100. Fig. 2(b) is a partial perspective view of the bagging sheet 100 on which ears 140 (tabs) are formed. The bagging sheet 100 is used to seal a repair space in VaRTM molding.

[0023] The bagging sheet 100 shown in Figure 2(a) has two pairs of three lines. Of the two pairs of three lines, one pair of three lines 110 is attached to the installation position of the vacuum suction tube 30, and the other pair of three lines 120 is attached to the installation position of the resin injection tube 40. In addition, a sealant tape 130 is attached to the edge of the bagging sheet 100 (including the lines 110 and 120 on the edge).

[0024] In this embodiment, ears 140 are formed on the bagging sheet as shown in Fig. 2(b). More specifically, using the three lines 110 and 120 shown in Fig. 2(a) as guides, the edges of the bagging sheet 100 are folded in the order of valley fold, mountain fold, and valley fold. As a result, the sealant tape 130 is adhered to the inside of the bagging sheet 100 as shown in Fig. 2(b), and ears 140 are formed at the installation positions of the vacuum suction tube 30 and the resin injection tube 40 on the bagging sheet 100.

[0025] Figure 3 is a diagram illustrating the attachment of a bagging sheet 100 to a steel pipe 10. Figure 3(a) shows a state in which a resin diffusion sheet 26 is laminated on a peel ply 24 in the steel pipe 10 to be repaired. The following explanation illustrates the case in which the bagging sheet 100 is installed on a resin injection tube 40, but the procedure for installing it on a vacuum suction tube 30 is similar.

[0026] In the VaRTM molding method of this embodiment, as shown in Figure 3(a), the resin injection tube 40 is fixed to the peel ply 24 using a sealant tape 50. Next, the bagging sheet 100, which has ears 140 made as shown in Figure 2(b), is attached to the steel pipe 10 so that the ears 140 are positioned at the position of the resin injection tube 40 as shown in Figure 3(b). As a result, the edges of the bagging sheet 100 are adhered to the steel pipe 10 with the sealant tape 130, and the resin injection tube 40 is inserted into the bagging sheet 100.

[0027] At this time, because the bagging sheet 100 has ears 140, the bagging sheet 100 is bent at a right angle beside the resin injection tube 40. This allows the bagging sheet 100 to be fitted to the corner of the resin injection tube 40 and the steel pipe 10 with little force, and no gaps are left beside the resin injection tube 40. Then, sealant tape 60 is wrapped around the resin injection tube 40 at the position corresponding to the ears 140 to increase its thickness. This seals the inside of the bagging sheet 100.

[0028] As described above, in the bagging sheet 100 of this embodiment and the VaRTM molding method using the same, tubes (vacuum suction tubes 30 and resin injection tubes 40) are inserted into the ears 140 formed by folding the bagging sheet 100. This prevents gaps from forming between the bagging sheet 100 and the tubes. Therefore, the inside of the bagging sheet 100 can be efficiently evacuated, improving work efficiency.

[0029] In particular, the bagging sheet 100 of this embodiment has lines 110 and 120 formed thereon to indicate the positions where the selvages 140 are to be formed (see FIG. 2(a)). This allows the worker to visually determine the positions where the selvages 140 are to be formed.

[0030] In this embodiment, a configuration in which one pair is formed by each of the three lines 110 and 120 that serve as indicators for the three folds (valley fold, mountain fold, valley fold) has been exemplified, but the present invention is not limited to this. For example, the ear 140 can be folded by drawing lines at the two valley fold locations, or the ear 140 can be folded by drawing lines at the mountain fold and one valley fold location. In other words, as long as lines are drawn at at least two locations (folds) out of the three folds, the ear 140 can be formed, and the above-mentioned effects can be obtained.

[0031] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that these modifications and alterations also fall within the technical scope of the present invention. [Industrial Applicability]

[0032] The present invention can be used as a bagging sheet for VaRTM molding that seals a repair space in VaRTM molding, and as a VaRTM molding method using the same. [Explanation of symbols]

[0033] 10...steel pipe, 12...opening, 20...adhesive layer sheet, 22...reinforced fiber sheet, 24...peel ply, 26...resin diffusion sheet, 30...vacuum suction tube, 40...resin injection tube, 42...resin tank, 50...sealant tape, 60...sealant tape, 100...bagging sheet, 110...wire, 120...wire, 130...sealant tape, 140...ear

Claims

1. In the bagging sheet that seals the repair space in VaRTM molding, The bagging sheet has lines on it, A bagging sheet for VaRTM molding, characterized in that by using the lines as indicators and folding the edges of the bagging sheet in the order of valley fold, mountain fold, and valley fold, ears are formed at the installation positions of tubes for vacuum suction or resin injection, and the tubes can be inserted into the ears.

2. 2. The bagging sheet for VaRTM molding according to claim 1, wherein the lines are provided at least at two of three folds: a valley fold, a mountain fold, and a valley fold.

3. A VaRTM molding method, characterized by using the bagging sheet according to claim 1 or 2.

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