Method for manufacturing tank

Abstract

To provide a technique that can smooth a seal surface of an opening of a tank.SOLUTION: A method for manufacturing a tank comprises: a winding process of winding reinforcing fibers, which are impregnated with a resin that hardens when heated to a predetermined hardening temperature lower than a melting temperature, around a core member having a metal member installed at a tip, the core member melting when heated to a predetermined melting temperature; a thermosetting process of heating the resin to a temperature equal to or higher than the hardening temperature and lower than the melting temperature to harden the resin and form an outer shell of the tank; an elution process of heating the core member to a temperature equal to or higher than the melting temperature to elute the core member from the outer shell; and a removal process of removing the metal member from the outer shell.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a tank. [Background technology]

[0002] A technique for manufacturing a linerless tank using a core member with leachability is known (Patent Document 1). In this technique, a core member is preformed to the shape of the tank's inner wall, and a resin-impregnated reinforcing fiber is wound around the surface of the core member, which is then heated to a temperature lower than the melting point of the core member. This hardens the resin, forming the outer shell of the container from fiber-reinforced plastic (FRP). The core member is then heated to a temperature higher than its melting point, causing it to leach out, resulting in a tank with an internal cavity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-323365 Summary of the Invention [Problem to be solved by the invention]

[0004] A plug is inserted into the opening of the tank to inject fluid into the tank and to drain the fluid stored in the tank from the tank. In this case, the airtightness of the tank is ensured, for example, by sealing the gap between the opening of the tank and the plug with a sealing member. Therefore, it is preferable that the sealing surface of the tank that comes into contact with the sealing member is smooth. When wax is used as the core member, the wax may soften or thermally expand during the process of hardening the resin impregnated into the reinforcing fibers, causing the wax to bite into the reinforcing fibers. If the resin impregnated into the reinforcing fibers hardens with the wax biting into them, the sealing surface of the tank may become rough, potentially reducing the airtightness of the tank provided by the sealing member. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] According to one aspect of the present disclosure, a method for manufacturing a tank is provided. The method includes a winding step of winding reinforcing fibers impregnated with a resin that hardens when heated to a predetermined hardening temperature lower than the melting temperature around a core member having a metal member at its tip end. The core member melts when heated to a predetermined melting temperature. A thermosetting step of heating the resin to a temperature equal to or higher than the hardening temperature but lower than the melting temperature to harden the resin and form an outer shell of the tank. An elution step of eluting the core member from the outer shell by heating the core member to a temperature equal to or higher than the melting temperature. And a removal step of removing the metal member from the outer shell. According to this aspect, because the metal member is provided at the tip end of the core member, the outer shell can be formed without the core member contacting the sealing surface that contacts the sealing member at the opening of the tank. This prevents the core member from biting into the reinforcing fibers even if the core member softens or thermally expands during the hardening process of the resin impregnated in the reinforcing fibers. This prevents the resin impregnated in the reinforcing fibers from hardening and creating a rough seal surface when the core member is embedded in the reinforcing fibers, making the seal surface smoother and preventing a decrease in the airtightness of the tank due to the seal member. The present disclosure can be realized in various forms other than the above-described tank manufacturing method, for example, in the form of a tank manufacturing apparatus, etc. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing a schematic configuration of a tank. [Figure 2] 10A to 10C are diagrams showing a manufacturing method of the tank. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. Implementation: FIG. 1 is a diagram showing a schematic configuration of a tank 1. The tank 1 has a linerless structure. The tank 1 is, for example, a high-pressure tank that is mounted on a fuel cell vehicle and stores hydrogen gas at high pressure to be supplied to the fuel cell. The tank 1 includes an outer shell 10. The outer shell 10 is a hollow container that forms an interior space 100 for storing a fluid. The outer shell 10 is formed from a material, for example, a fiber-reinforced resin such as carbon fiber reinforced plastics (CFRP). The outer shell 10 includes a cylindrical portion 11, a dome portion 13, and an opening 15. The cylindrical portion 11 has a cylindrical shape with a central axis O. The dome portion 13 is connected to both ends of the cylindrical portion 11. The dome portion 13 has a dome shape with a diameter that decreases with increasing distance from the cylindrical portion 11. The opening 15 is connected to the dome portion 13. The opening 15 has a cylindrical shape with a central axis O. The diameter of the opening 15 is smaller than the diameter of the cylindrical portion 11. A plug 8 is inserted into the opening 15 to inject fluid to be stored in the tank 1 or to discharge fluid stored in the tank 1 from the tank 1. A seal member 9 seals the gap between an inner wall 150 of the opening 15 and an outer wall 80 of the plug 8. The seal member 9 is, for example, an O-ring.

[0009] FIG. 2 illustrates a manufacturing method of the tank 1. In a preparation step, a core member 5 for forming the interior space 100 in the tank 1 is prepared. The core member 5 is melted by heating to a predetermined melting temperature. The melting temperature of the core member 5 is, for example, 150°C. The core member 5 is formed from a thermoplastic lost wax material. For example, Ferris WAX Turquoise manufactured by Freeman, which has a melting point of 117°C, can be used as the lost wax material. A metal member 6 is attached to a tip end 50 of the core member 5. The tip end 50 of the core member 5 is a portion of the inner wall 150 of the opening 15 that forms a sealing surface 155 that contacts the sealing member 9. The metal member 6 has a cylindrical shape that conforms to the shape of the opening 15. The material for the metal member 6 includes, for example, aluminum. The maximum height Rz, which represents the surface roughness of the metal member 6, is, for example, 3.0 μm or more and 3.4 μm or less. In the preparation process, a mold for molding the core member 5 is prepared by using a master formed to the shape of the inner wall of the outer shell 10 as a core and molding it with silicone or the like. Molten lost wax is poured into the mold for molding the core member 5. Before the lost wax solidifies, the metal member 6 is attached to the tip 50 of the core member 5. After the metal member 6 is attached, the lost wax solidifies, and the core member 5 with the metal member 6 attached to the tip 50 is prepared.

[0010] Following the preparation step, a winding step is carried out. In the winding step, reinforcing fibers F impregnated with resin are wound around the core member 5. The resin impregnated into the reinforcing fibers F is hardened by heating to a predetermined hardening temperature that is lower than the melting temperature of the core member 5. The hardening temperature of the resin impregnated into the reinforcing fibers F is, for example, 80°C or higher and 90°C or lower.

[0011] Following the winding step, a thermal curing step is carried out. In the thermal curing step, the resin impregnated into the reinforcing fibers F is heated for a predetermined heating time to a temperature equal to or higher than the curing temperature of the resin impregnated into the reinforcing fibers F and lower than the melting temperature of the core member 5. The heating time for the resin impregnated into the reinforcing fibers F is, for example, one hour. In this way, the resin impregnated into the reinforcing fibers F is cured without dissolving the core member 5, thereby forming an outer shell 10 made of fiber reinforced plastics (FRP).

[0012] Following the thermal hardening step, a dissolution step is carried out. In the dissolution step, the core member 5 is heated to a temperature equal to or higher than the melting temperature of the core member 5 for a predetermined heating time. The heating time for the core member 5 is, for example, one hour. As a result, the core member 5 is dissolved from the outer shell 10.

[0013] After the elution step, a removal step is carried out in which the metal member 6 is removed from the outer shell 10.

[0014] According to the above embodiment, the metal member 6 is provided at the tip 50 of the core member 5, so the outer shell 10 can be formed without the core member 5 coming into contact with the sealing surface 155 at the opening 15. This prevents the core member 5 from biting into the reinforcing fibers F even if the core member 5 softens or thermally expands during the process of curing the resin impregnating the reinforcing fibers F. This prevents the sealing surface 155 from becoming rough when the resin impregnating the reinforcing fibers F hardens while the core member 5 is biting into the reinforcing fibers F, making the sealing surface 155 smooth. This prevents a decrease in the airtightness of the tank 1 due to the sealing member 9.

[0015] Furthermore, according to the above embodiment, the shape of the tip end 50 of the core member 5 can be maintained by the metal member 6. In this way, even if the core member 5 is thermally deformed in the process of curing the resin impregnated in the reinforcing fibers F, it is possible to prevent the roundness of the sealing surface 155 from decreasing.

[0016] B. Other Embodiments: The tank 1 may have components other than the outer shell 10. For example, the tank 1 may have a protective layer on at least one of the inner wall surface and the outer wall surface of the outer shell 10 to prevent the fluid stored in the internal space 100 from passing through the outer shell 10 and being discharged to the outside, or to prevent deterioration of the outer shell 10. The tank 1 may also have a protective layer on the outer wall surface of the outer shell 10 to protect the outer shell 10 from external impacts, for example.

[0017] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0018] 1...tank, 5...core member, 6...metal member, 8...plug, 9...seal member, 10...outer shell, 11...cylindrical portion, 13...dome portion, 15...opening, 50...tip portion, 80...outer wall of plug, 100...internal space, 150...inner wall of opening, 155...seal surface, F...reinforcing fiber, O...central axis

Claims

[Claim 1] A method for manufacturing a tank, comprising: a winding step of winding reinforcement fibers impregnated with a resin that hardens when heated to a predetermined hardening temperature lower than the melting temperature around a core member having a metal member at its tip end, the core member being melted when heated to a predetermined melting temperature; a thermosetting process of heating the resin to a temperature equal to or higher than the hardening temperature but lower than the melting temperature to harden the resin, thereby forming an outer shell of the tank; an elution step of eluting the core member from the outer shell by heating the core member to the melting temperature or higher; a removal step of removing the metal member from the outer shell.

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