Method for manufacturing a tank

Abstract

To provide a tank production method in which the fiber volume density of a fiber layer wound on the outer periphery of a liner is increased, and which thereby enables the pressure resistance of the tank to be stably increased.SOLUTION: There is provided a method for producing a tank comprising a liner 11 in which fluid is filled, and a fiber-reinforced resin layer covering the outer periphery of the liner. The method includes: a step of winding a fiber bundle 25 constituting the fiber-reinforced resin layer on the outer periphery of the liner 11 thereby forming a fiber layer 16; and a step of arranging the liner on which the fiber layer is formed in a mold 40 and injecting resin into the mold thereby impregnating the fiber layer with the resin thereby forming the fiber-reinforced resin layer, wherein the fiber bundle is obtained by joining continuous fibers to each other by a sizing agent. In the step of forming the fiber layer 16, the fiber bundle 25 is wound on the outer periphery of the liner 11 while heating the fiber bundle for softening the sizing agent.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a tank, and more particularly, to a method for manufacturing a tank for storing hydrogen supplied to a fuel cell system, for example.

Background Art

[0002] Conventionally, as a manufacturing method of this type, a fiber bundle constituting a fiber-reinforced resin layer is wound around the outer peripheral surface of a liner to form a fiber layer. After that, the liner with the fiber layer formed thereon is placed in a mold, and resin is injected into the mold to impregnate the fiber layer with the resin, thereby forming a fiber-reinforced resin layer. A manufacturing method of a high-pressure tank has been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the manufacturing method of the high-pressure tank shown in Patent Document 1, when winding the fiber bundle, the fibers of the fiber layer may not reach a predetermined fiber volume density. For this reason, the pressure resistance of the high-pressure tank cannot be stably increased.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide a method for manufacturing a tank capable of stably increasing the pressure resistance of the tank by increasing the fiber volume density of the wound fiber layer when forming a fiber layer by winding a fiber bundle around the outer peripheral surface of a liner.

Means for Solving the Problems

[0006] In view of the above problems, the method for manufacturing a tank according to the present invention is a method for manufacturing a tank including a liner filled with a fluid and a fiber reinforced resin layer coated on an outer peripheral surface of the liner, and includes the steps of winding a fiber bundle constituting the fiber reinforced resin layer around the outer peripheral surface of the liner to form a fiber layer, and placing the liner with the fiber layer formed thereon in a mold and injecting resin into the mold to impregnate the fiber layer with the resin, thereby forming the fiber reinforced resin layer, wherein the fiber bundle is made of continuous fibers bonded together with a sizing agent, and in the step of forming the fiber layer, the fiber bundle is wound around the outer peripheral surface of the liner while heating the fiber bundle so that the sizing agent is softened.

[0007] In the manufacturing method of the tank of the present invention configured as described above, in the step of winding the fiber bundles constituting the fiber reinforced resin layer around the outer peripheral surface of the liner to form the fiber layer, the fiber bundles in which the continuous fibers are bonded together with a sizing agent are wound around the outer peripheral surface of the liner while being heated so that the sizing agent is softened. As a result, the fiber bundles become soft and are easily compressed overall, so that the fiber bundles can be wound evenly, and the fiber volume density of the fiber layer can be increased while suppressing the variation of the fiber bundles. As a result, the pressure resistance of the tank can be improved. Effect of the Invention

[0008] According to the present invention, the fiber bundle can be wound uniformly around the outer peripheral surface of the liner, the fiber volume density of the fiber layer can be increased, and the pressure resistance of the tank can be improved. [Brief description of the drawings]

[0009]

Figure 1

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Figure 7

[0010] An embodiment of the method for manufacturing a tank according to the present invention will be described in detail below with reference to the drawings. Fig. 1 is a front view showing a schematic appearance of a tank manufactured by the method for manufacturing a tank according to this embodiment, and Fig. 2 shows a mode of winding a fiber bundle around the tank shown in Fig. 1, where (a) is a front view showing hoop winding, (b) is a front view showing helical winding, and (c) is a front view of a main part showing braider winding.

[0011] 1 and 2, a tank 10 manufactured by the tank manufacturing method of this embodiment stores hydrogen to be supplied to a fuel cell system, for example. Such a tank 10 includes a liner 11 filled with a fluid such as hydrogen, and a fiber layer 16 covering the outer circumferential surface of the liner 11. The liner 11 constituting the tank 10 is made of resin, and a reinforcing fiber layer 16 is formed by winding, for example, multiple layers of fiber bundles 25 of carbon fiber around the outer periphery of the resin liner 11, and a fiber-reinforced resin layer is formed by impregnating the fiber layer with resin.

[0012] The liner 11 constitutes the core of the tank and has a cylindrical body portion 12 and substantially hemispherical dome portions 13, 13 disposed at both left and right ends of the body portion 12, respectively. The liner 11 is integrally formed, for example, by a rotational blow molding method using a resin member such as polyethylene or nylon. Further, the liner 11 may be formed of a light metal such as aluminum instead of the resin member. Furthermore, the liner 11 may be formed by joining members divided into a plurality by injection extrusion molding or the like instead of an integral molding manufacturing method such as the rotational blow molding method.

[0013] Openings (not shown) are respectively formed at the tops of the dome portions 13, 13, and base portions 14, 15 are attached to the openings. Specifically, as shown in FIG. 1, the base portion 14 is inserted into the opening of the left dome portion 13, and the base portion 15 is inserted into the opening of the right dome portion 13. The base portion 14 functions as, for example, a valve-side base, and the base portion 15 functions as, for example, an end-side base. These base portions 14, 15 are formed in a cylindrical shape from a metal material, one end is inserted into the opening of one dome portion 13, and the other end protrudes externally along the central axis L of the liner 11 from the other dome portion 13.

[0014] In the tank 10 configured as described above, a fiber layer 16 that constitutes a fiber-reinforced resin layer coated on the outer peripheral surface of the liner 11 is formed. The fiber layer 16 can change the winding mode, such as helical winding, hoop winding, and braider winding, by a filament winding device that winds a fiber bundle 25 such as a carbon fiber around the outer peripheral surface of the liner 11, or a braider 20 described later. The helical winding is a mode in which the fiber bundle 25 is wound in a spiral shape so that the angle (so-called winding angle) formed by the central axis L of the liner 11 and the winding direction of the fiber bundle 25 is greater than 0° and less than 90°, as shown in FIG. 2(b). By this helical winding, a helical layer is formed.

[0015] On the one hand, hoop winding is a method of winding the fiber bundle 25 in the circumferential direction of the liner 11 such that the winding angle formed by the central axis L of the liner 11 and the winding direction of the fiber bundle 25 is substantially perpendicular, as shown in Fig. 2(a). Here, "substantially perpendicular" means including both 90° and an angle of around 90° that can occur by shifting the winding position of the fiber bundle 25 so that adjacent fiber bundles 25 do not overlap. And by hoop winding, a hoop layer is formed.

[0016] Also, helical winding is further divided into low-angle helical winding and high-angle helical winding according to the magnitude of the winding angle. Low-angle helical winding is helical winding when the winding angle is small (for example, greater than 0° and less than or equal to 30°), and it is a winding mode in which the fiber bundle 25 makes a U-turn in the winding direction of the fiber bundle 25 in the dome portions 13, 13 before making one full turn around the central axis L of the liner 11.

[0017] High-angle helical winding is helical winding when the winding angle is large (for example, greater than 30° and less than 90°), and it is a winding mode in which the fiber bundle 25 makes at least one full turn around the central axis L of the liner 11 in the body portion 12 before the fiber bundle 25 makes a U-turn in the winding direction in the dome portions 13, 13. Note that Fig. 2(b) shows low-angle helical winding. In this way, by combining the helical winding and hoop winding in Figs. 2(a) and (b), the fiber layer 16 described later may be formed. However, for example, as shown in Fig. 2(c), the fiber layer 16 may be formed by blade winding.

[0018] Furthermore, blade winding is a method of forming the fiber layer 16 by knitting a wide fiber bundle 25 onto the outer peripheral surface of the liner 11, as shown in Fig. 2(c). This blade winding is wound by a blade (braiding machine) 20 described later. A bobbin wound with a large number of fiber bundles 17(25) is arranged at the outer peripheral portion of the liner 11, and while knitting a large number of fiber bundles 25 drawn from a large number of bobbins, the fiber layer 16 is formed on the outer peripheral surface of the liner 11.

[0019] Next, the braider (braiding machine) 20 that wraps a plurality of layers of fiber bundles around the outer periphery of the liner 11 will be described with reference to FIGS. 3 and 4. In FIGS. 3 and 4, the braider 20 includes a disk 21 supported by a base (not shown), a moving mechanism (not shown) that supports the liner 11 constituting the tank 10 and moves the liner 11 in the axial direction of the axis C. The disk 21 has a through hole 22 in the center around the axis C. The through hole 22 is set to a size through which the liner 11 can pass. Therefore, the liner 11 is configured to move within the through hole 22 by the moving mechanism.

[0020] A concave spherical surface 23 centered on the axis C is formed on the disk 21, and a plurality of carriers 24 are arranged on the concave spherical surface so as to be movable in the circumferential direction and the radial direction by a moving mechanism (not shown) along the concave spherical surface. A bobbin 26 around which a fiber bundle 25 is wound is rotatably supported by the carrier 24. The rotation axes of the bobbins 26 are arranged so as to face the axis C of the disk 21. Therefore, the fiber bundle 25 wound around the bobbin 26 extends from the bobbin 26 and is wound around the outer peripheral surface of the liner 11 of the tank 10 as the carrier 24 moves and the liner 11 moves in the axial direction of the axis C. Depending on the movement mode, braider winding is performed to form a fiber layer 16 that reinforces the liner 11 of the tank 10. Note that the fiber bundle 25 is substantially equivalent to the above-described fiber bundle 25.

[0021] The fiber bundle 25 is formed by bundling continuous fibers with a diameter of about several μm and binding them with a sizing agent. The surface of the carbon fibers constituting the fiber bundle 25 is coated with a generally known sizing agent such as an uncured thermosetting resin. Examples of the continuous fibers include fibers such as glass fibers, carbon fibers, aramid fibers, alumina fibers, boron fibers, steel fibers, PBO fibers, natural fibers, or high-strength polyethylene fibers. In this embodiment, carbon fibers are used. Examples of the sizing agent include epoxy resins, modified epoxy resins typified by vinyl ester resins, phenol resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, polyurethane resins, and thermosetting polyimide resins. The sizing agent refers to a small amount of resin present to maintain the shape of the fiber bundle, and is added to the fiber bundle 25 at about 1.1% (by volume).

[0022] Therefore, when the fiber bundle 25 is heated to a predetermined temperature (below the curing start temperature), the thermosetting resin, which is the sizing agent, softens, and the flexibility of the fiber bundle 25 increases, making it easier to wind around the liner 11, enabling high-speed winding. At the same time, the Vf (fiber volume density) of the liner 11 after winding can be improved, and the variation in Vf can be reduced. In this embodiment, a thermoplastic resin may be used as the sizing agent.

[0023] In the method for manufacturing the tank of this embodiment, as shown in FIG. 4, a series of steps from heating the liner 11 to winding the fiber bundle 25 around the outer peripheral surface of the liner 11 can be carried out in the heating chamber 30. A hot air generator 31 is connected to the heating chamber 30, and the temperature inside the heating chamber 30 can be set to an arbitrary temperature, for example, from 50 to 100°C. The liner 11 disposed inside the heating chamber 30 is heated to a predetermined temperature. Then, it is moved rightward in FIG. 4, and the fiber bundle 25 supplied from the blader 20 is heated in the heating chamber 30 to raise the temperature and is wound around the outer peripheral surface of the liner 11. The liner 11A shows a state in which the fiber bundle 25 is wound up to a certain point and the fiber layer 16 is formed.

[0024] Next, the fiber bundle 25 is wound from the blade 20, and in the liner 11B, winding around the entire outer peripheral surface is completed, and the fiber layer 16 is formed. The fiber layer 16 is formed in a state of being stacked in a plurality of layers. In this case, the plurality of liners 11, 11 are connected in the axial direction and reciprocated a plurality of times. The steps up to this point are carried out in the heating chamber 30. Finally, the connected liners 11, 11 are cut at the connection part.

[0025] Note that in the heating chamber 30, an expanded chamber 30a with a wide width is formed at the part where the fiber bundle 25 is supplied, and by lengthening the residence time of the fiber bundle 25 in the heating chamber, the temperature rise of the fiber bundle can be stabilized. As a result, the fiber volume density Vf of the fiber layer 16 can be increased. After that, although not shown, the liner 11B with the fiber layer 16 formed on the entire outer periphery is taken out from the heating chamber 30, and after quality inspection, the formation of a fiber reinforced resin layer by impregnating the fiber layer 16 with resin is carried out.

[0026] Next, the mold 40 for impregnating the resin into the fiber bundle 25 in a state where the fiber bundle 25 is wound in a plurality of layers, that is, the fiber layer 16, will be described with reference to FIG. 5. The mold 40 includes an upper mold 41 and a lower mold 42 coupled to the upper mold 41. In the assembled state of the upper mold 41 and the lower mold 42, an internal space 45 along the shape of the liner 11 is formed inside the mold 40. By separating the upper mold 41 and the lower mold 42, the liner 11 can be placed and accommodated in the internal space 45 in the mold 40, and the accommodated liner 11 can be taken out. The mold 40 is an injection mold for impregnating the resin into the liner 11 accommodated in the internal space 45, and in this example, a metal mold is used for the upper mold 41 and the lower mold 42.

[0027] The upper mold 41 is formed with a flow path 43 that communicates with the internal space from the outside, and the internal space can be depressurized through the flow path 43. Further, as a resin composition, an uncured thermosetting resin similar to that exemplified by the sizing agent described above is injected into the mold 40 through the flow path 43. Thereby, the fiber layer 16 formed by the fiber bundle 25 wound around the liner 11 can be impregnated with the resin. By impregnating the fiber layer 16 with the resin, a fiber-reinforced resin layer can be formed, and the liner 11 can be reinforced. It is preferable that the mold 40 is provided with heating means and temperature control means (not shown).

[0028] The operation of the method for manufacturing the tank according to the present embodiment configured as described above will be described below. In the method for manufacturing the tank 10 configured as described above, in the step of winding a fiber bundle around the outer peripheral surface of the liner 11 to form a fiber layer, the sizing agent binds the continuous fibers to each other to form a fiber bundle 25. While heating the fiber bundle 25 so that the sizing agent softens, it is wound around the outer peripheral surface of the liner 11.

[0029] That is, in FIG. 4, when the liner 11 is placed in the heating chamber 30 and the hot air generator 31 is operated to raise the temperature in the heating chamber 30, the liner 11 itself is also heated. At this time, it is preferable to measure the surface temperature of the liner 11 with a thermocouple thermometer or the like to confirm whether it is within a predetermined temperature range. After that, the liner 11 is moved to the winding position of the blader 20, the fiber bundle 25 wound around the bobbin 26 is extended, and wound around the outer peripheral surface of the liner 11. The carrier 24 is moved along the concave spherical surface 23, and the liner 11 is moved in the direction of the axis C to wind the fiber bundle 25 around the outer peripheral surface of the liner. When forming a plurality of layers of the fiber layer 16, the positions of the liner 11A and the liner 11B are reciprocated.

[0030] In the manufacturing method of this embodiment, when winding the fiber bundle 25 around the outer peripheral surface of the liner 11, it is wound while heating so that the sizing agent binding the fiber bundle 25 softens. For this reason, the sizing agent softens, the bonding between the continuous fibers becomes soft, and the shape of the fiber bundle 25 easily follows the shape of the winding portion. As a result, the fiber layer 16 wound around the outer peripheral surface of the liner 11 is easily compressed, the fiber bundle 25 is uniformly wound around the outer peripheral surface of the liner 11, and the close contact state becomes good. After that, the liner 11 formed with the fiber layer 16 wound with the fiber bundle 25 is disposed in the mold 40, and resin is injected into the mold 40 to impregnate the fiber layer 16 with the resin to form a fiber reinforced resin layer. In this way, the liner 11 formed with the fiber layer 16 can increase the fiber volume density Vf. And by increasing the fiber volume density Vf, the pressure resistance of the tank 10 is improved.

[0031] Hereinafter, while changing the winding method of the fiber bundle 25 wound around the liner 11, with reference to FIGS. 6 and 7, the change in the fiber volume density Vf in the fully wound fiber layer when wound in multiple layers at room temperature and when wound in multiple layers in a heated state will be described. In the table showing the specifications of FIG. 7, "all blade" is a mode in which all of the body portion 12 and the dome portions 13, 13 of the liner 11 are blade wound (= woven in). Further, "switching" is a mode in which the portion from the liner end to the dome-shaped dome portion 13 is blade wound (= woven in), and the straight body portion 12 is switched to helical winding (not woven in).

[0032] In FIGS. 6 and 7, the circles, triangles, squares, crosses, and dots respectively indicate the heating state and each specification of the winding method. Specifically, the circles and triangles are in a room temperature state without heating, and all of the 1st to 16th layers of the fiber layer are "all blade", and all of the body portion 12 and the dome portions 13, 13 of the liner 11 are blade wound (= woven in).

[0033] For the □ mark, at room temperature without heating, from 1 to 15 layers of the fiber layer, in the "switching" mode, the dome parts 13, 13 that are dome-shaped from the liner end are blade-wound (= knitted in), and the straight body part 12 is helically wound (not knitted in). For 16 layers, in the "all blades" mode, the entire body part 12 of the liner 11 and the dome parts 13, 13 are blade-wound (= knitted in).

[0034] For the × mark, at room temperature without heating, in the fiber layers of 1, 2 layers, 4, 5 layers, 7, 8 layers, 10, 11 layers, 13, 14 layers, in the "switching" mode, the dome parts 13, 13 that are dome-shaped from the liner end are blade-wound (= knitted in), and the straight body part 12 is helically wound (not knitted in). In the fiber layers of 3, 6 layers, 9, 12 layers, 15, 16 layers, in the "all blades" mode, the entire body part 12 of the liner 11 and the dome parts 13, 13 are blade-wound (= knitted in).

[0035] For the ● mark, in the heated state, in the fiber layers of 3, 4 layers, 6, 7 layers, 9, 10 layers, 12, 13 layers, 15 layers, in the "switching" mode, the dome parts 13, 13 that are dome-shaped from the liner end are blade-wound (= knitted in), and the straight body part 12 is helically wound (not knitted in). In the fiber layers of 1, 2 layers, 5, 8 layers, 11, 14, 16 layers of the fiber bundle, in the "all blades" mode, the entire body part 12 of the liner 11 and the dome parts 13, 13 are blade-wound (= knitted in).

[0036] And as shown in Fig. 6, when the fiber layer is wound at room temperature of 2 to 21 °C without heating at the liner surface temperature, as shown by the ○ mark, ▲ mark, × mark, and □ mark, the fiber volume density Vf of the fiber layer has a large variation as shown in the ranges A1, A2, and is a small value of 47 to 57%. In contrast, when the fiber layer is wound in the heated state at the liner surface temperature of 52 to 54 °C, as shown by the ● mark, the fiber volume density Vf of the fiber layer has a small variation as shown in the ranges B1, B2, and is a large value of 61 to 64%.

[0037] Thus, when forming the fiber layer 16 by winding the fiber bundle 25 around the outer peripheral surface of the liner 11, if the fiber bundle 25 is wound around the outer peripheral surface of the liner 11 while being heated so that the sizing agent that binds the continuous fibers of the fiber bundle softens, the variation in the fiber volume density Vf of the fiber layer 16 can be reduced, and the numerical value of Vf can be improved. As a result, the strength of the fiber-reinforced resin layer coated on the outer peripheral surface of the liner 11 can be increased, and the pressure resistance of the tank 10 can be enhanced.

[0038] In addition, in the above-described embodiment, as shown in FIG. 4, as a step of winding the fiber bundle 25 around the outer peripheral surface of the liner 11 while heating, an example was shown in which three liners were accommodated in the heating chamber 30 and continuously carried out. However, the number is not limited to three, and it may be configured to carry out more liners continuously while transporting.

[0039] As described above, one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, and various design changes can be made without departing from the spirit of the present invention described in the claims. The present invention can add the configuration of one embodiment to the configuration of another embodiment, replace the configuration of one embodiment with that of another embodiment, or delete a part of the configuration of one embodiment.

[0040] As an example of winding the fiber bundle constituting the fiber-reinforced resin layer around the outer peripheral surface of the liner, an example of winding the fiber bundle 25 around the liner 11 by the blader 20 has been shown, but it may be helically wound or hoop wound. As a means of heating so as to soften the sizing agent that binds the continuous fibers of the fiber bundle, an example of blowing hot air generated by the hot air generator 31 into the heating chamber 30 has been shown, but it may be appropriately changed, such as heating by an electric heater.

Explanation of Reference Numerals

[0041] 10: Tank, 11: Liner, 20: Blader (braiding machine), 16: Fiber layer, 25: Fiber bundle, 30: Heating chamber, 31: Hot air generator, 40: Mold, Vf: Fiber volume density

Claims

Claim 1 A method for manufacturing a tank comprising a liner filled with a fluid therein and a fiber-reinforced resin layer coated on an outer peripheral surface of the liner, the method comprising: winding a fiber bundle constituting the fiber-reinforced resin layer around the outer peripheral surface of the liner to form a fiber layer; placing the liner having the fiber layer formed thereon in a mold, and injecting a resin into the mold to impregnate the fiber layer with the resin to form the fiber-reinforced resin layer; wherein the fiber bundle is formed by binding continuous fibers with a sizing agent; In the step of forming the fiber layer, while the liner is placed in a heating chamber, hot air from a hot air generator is blown into the heating chamber to heat the liner together with the fiber bundle in the heating chamber so that the sizing agent softens, and the fiber bundle is wound around the outer peripheral surface of the liner. A method for manufacturing a tank, characterized in that.

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