JP7544003B2 - Tank manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a tank that is reinforced (strengthened) with fibers.

Patent Document 1 discloses a method for manufacturing an FRP tank (hereinafter also referred to as a high-pressure tank). In this manufacturing method, a coating process is carried out in which fibers are wrapped around the liner to cover it, followed by an impregnation process in which the fibers are impregnated with resin, and then the resin-impregnated fibers are heated to harden the resin.

Patent Document 2 also discloses a method for manufacturing a high-pressure tank using this RTM (Resin Transfer Molding) method. In this manufacturing method, a preform in which a fiber layer is formed on the outer surface of a liner that forms the internal space of the high-pressure tank is placed in a mold, and the preform is rotated in the circumferential direction within the mold around the central axis of the preform as the center of rotation while resin is injected from a gate toward the preform placed in the mold.

JP 2020-085199 A JP 2019-056415 A

In the manufacturing method using the RTM method, the fiber winding process and the resin impregnation process are carried out separately when manufacturing a high-pressure tank. However, because the amount of fiber wound on a high-pressure tank is large and the fiber layer (lamination) formed by winding the fiber is thick, it takes time to impregnate the resin deep into the fiber layer (innermost layer), and there is a possibility that some parts may not be impregnated.

The present invention was made in consideration of the above circumstances, and aims to provide a method for manufacturing a tank that can impregnate resin deep into the fiber layer (the innermost layer) in a short period of time.

To achieve the above object, one aspect of the present invention is characterized by including a preform placement step in which a preform having a fiber layer formed by wrapping fiber around the outer surface of a hollow liner is placed in a mold; an adhesion imparting step in which adhesiveness is imparted to the inner surface of the mold to form gaps in the fiber layer of the preform; and a resin injection step in which resin is injected into the mold to impregnate the fiber layer with the resin.

In another embodiment, in the adhesiveness imparting step, adhesiveness may be imparted to the inner surface of the mold by filling the mold with liquid nitrogen gas, applying a resin to the inner surface of the mold, or charging the inner surface of the mold with static electricity.

In another embodiment, in the adhesive imparting step, adhesiveness may be imparted to the inner surface of the mold, and a portion of the mold may be spaced relatively away from the preform, or a portion of the mold may be ultrasonically vibrated relative to the preform to form a gap in the fiber layer of the preform.

In another embodiment, in the adhesive imparting step, adhesiveness may be imparted to the inner surface of the mold, and a gap may be formed in the fiber layer of the preform by ultrasonically vibrating a portion of the mold relative to the preform while moving the portion of the mold relatively away from the preform.

In another embodiment, gaps may be formed in the fiber layer of the preform by ultrasonically vibrating a portion of the mold relatively in the longitudinal direction of the preform.

In another embodiment, in the adhesive imparting step, an inert gas may be discharged in the longitudinal direction of the preform to form gaps in the fiber layer of the preform.

In another embodiment, in the adhesive imparting step, adhesiveness may be imparted to the inner surface of the mold, and while a portion of the mold is spaced relatively away from the preform, the portion of the mold may be ultrasonically vibrated relative to the preform, and an inert gas may be ejected in the longitudinal direction of the preform to form gaps in the fiber layer of the preform.

In another aspect, the mold includes a first mold and a second mold, and in the preform placement step, the preform is placed between the first mold and the second mold so as to form a second gap between the second mold and the preform that is larger than a first gap between the first mold and the preform. In the adhesion imparting step, adhesion to the fiber layer of the preform is imparted to the inner surface of the mold, the fiber layer of the preform is adhered to the inner surface of the second mold by bringing the second mold relatively close to the preform, and while adhering the fiber layer of the preform to the inner surface of the second mold, the second mold is moved relatively away from the preform and ultrasonically vibrated relative to the preform to form a gap in the fiber layer of the preform. In the resin injection step, the second mold is brought relatively close to the preform, and then the resin is injected into the mold.

According to one aspect of the present invention, by floating the fibers to form gaps between the fiber layers (between the laminated layers) and then injecting and impregnating the resin, it is possible to impregnate the resin deep into the fiber layers (the innermost layer) in a short time.

1 is a vertical cross-sectional view showing a manufacturing apparatus for a high-pressure tank according to an embodiment of the present invention. 4 is a flowchart illustrating a method for manufacturing a high-pressure tank according to the embodiment. 3 is a flow chart illustrating the adhesion imparting step in FIG. 2. 4A to 4C are vertical cross-sectional views showing the states of a preform placement process and a vacuum degassing process of the high-pressure tank manufacturing apparatus according to the embodiment. 1 is a vertical cross-sectional view showing a liquid nitrogen gas filling process in an adhesiveness imparting process of a high-pressure tank manufacturing apparatus according to an embodiment of the present invention. FIG. 1 is a vertical cross-sectional view showing a state of an upper die lowering step in an adhesion imparting process of a high-pressure tank manufacturing apparatus according to an embodiment of the present invention. FIG. 1 is a vertical cross-sectional view showing a state of an upper die raising step in an adhesion imparting process of a high-pressure tank manufacturing apparatus according to an embodiment of the present invention. FIG. 4A to 4C are vertical cross-sectional views showing the final tightening process and the resin injection process of the high-pressure tank manufacturing apparatus according to the embodiment. 4A to 4C are vertical cross-sectional views showing the resin injection stopping step and the resin hardening step of the high-pressure tank manufacturing apparatus according to the embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

The following description uses a high-pressure tank for a fuel cell vehicle as an example of a tank. However, the tank to which the present invention is applicable is not limited to high-pressure tanks for fuel cell vehicles, and the shape and material of the liner or preform that constitutes the tank are not limited to the illustrated example.

In the RTM method, a preform is created in which a fiber layer is formed on the outer surface of the liner by wrapping (wrapping) carbon fiber around the liner in multiple layers, and the fiber layer of the preform is impregnated with epoxy resin and cured to produce a high-pressure tank for fuel cell vehicles in which a fiber-reinforced resin layer containing carbon fiber and epoxy resin is formed on the outer periphery of the liner. The liner is a hollow container made of resin (e.g., nylon resin) that forms the internal space of the high-pressure tank.

High-pressure tanks for fuel cell vehicles are made of thickly laminated carbon fibers, so the resin does not penetrate to the inner layers of the carbon fibers. If resin is injected at high pressure to penetrate to the inner layers of the carbon fibers, the tank itself will deform, resulting in a decrease in quality and performance. In addition, because the tank is cylindrical, it is difficult to fill the entire tank with resin evenly, and the resin is not impregnated evenly. In addition, pressure tends to concentrate near the gate, and the gate becomes highly pressurized, while the pressure difference between the gate and the resin flow terminal (the opposite side of the gate) is large.

In other words, the carbon fiber lamination thickness of the high-pressure tank for fuel cell vehicles is very thick (about 10 times that of normal RTM-molded body parts) to ensure strength, making resin impregnation difficult, but tank rotation as in Patent Document 2 does little to impregnate the inner layer of the carbon fiber with resin. Also, if resin is injected at high pressure to impregnate the inner layer of the carbon fiber, the pressure distribution becomes uneven, and in areas where the pressure is partially high, the resin liner inside the tank deforms, resulting in a decrease in quality and performance. Also, since the gap between the mold and the tank is narrow and it is difficult for resin to flow to the opposite side of the gate, in order to flow the resin throughout the entire tank before it hardens, it is necessary to rotate the tank at high speed in the mold as in Patent Document 2, but there is little space in the mold and the carbon fiber may be damaged.

Therefore, this embodiment adopts the following configuration:

[High pressure tank manufacturing equipment]
FIG. 1 is a vertical cross-sectional view showing a high-pressure tank manufacturing apparatus according to an embodiment of the present invention.

The preform 2, which serves as an intermediate for the high-pressure tank manufactured in this embodiment, includes a liner 4 and a fiber layer 5 formed on the outer surface of the liner 4 and integrated with the liner 4. The liner 4 is a hollow container made of resin with gas barrier properties that forms the internal space of the high-pressure tank. The hollow (in other words, cylindrical) liner 4 has a thickness of, for example, about 0.5 mm to 1 mm. The fiber layer 5 has a thickness of, for example, about 15 mm to 30 mm. The fiber layer 5 is formed by wrapping fibers multiple times around the outer surface of the liner 4 using a filament winding method.

The fibers wound around the liner 4 may be, for example, carbon fibers, glass fibers, aramid fibers, etc. The fibers may be made of continuous fibers, long fibers, or short fibers. As described below, a fiber-reinforced resin layer that covers the periphery of the liner 4 is formed by impregnating the fibers (layer) wound around the liner 4 with resin and curing it. The resin may be a thermosetting resin such as epoxy resin, unsaturated polyester resin, or polyamide resin, or a thermoplastic resin such as polyethylene resin or polyester resin.

The manufacturing device 1 uses the RTM (Resin Transfer Molding) method to impregnate the fiber layer 5 that constitutes the preform 2 with resin 6 (the symbol is shown in Figure 8), and then hardens the impregnated resin 6 to manufacture a high-pressure tank.

The manufacturing device 1 is equipped with a mold 10 consisting of multiple molds, for example, a lower mold 11 which is a fixed mold, and an upper mold 12 which is a movable mold. By closing the lower mold 11 and the upper mold 12 (also called mold clamping), a cavity for the fiber reinforced resin layer is formed. In order to place the preform 2 with laminated fibers inside the mold 10, for example, the cavity of the mold 10 is made larger by the tolerance of the preform 2.

Here, the lower mold 11 is a fixed mold and the upper mold 12 is a movable mold (a mold that can move relative to the fixed mold), but for example, the upper mold 12 may be a fixed mold and the lower mold 11 a movable mold, or both the lower mold 11 and the upper mold 12 may be movable molds. Also, here, the mold 10 is composed of two molds, the lower mold 11 and the upper mold 12, but it may be composed of three or more molds.

The preform 2 is supported in the mold 10 by a hollow shaft 25 that is arranged along the axis of the liner 4. In other words, the shaft 25 constitutes a support mechanism that supports the preform 2 in the mold 10 (inside the cavity).

A vacuum degassing pipe 15 is embedded in the mold 10 (lower mold 11 in the illustrated example). A vacuum pump 50 is connected to the vacuum degassing pipe 15. By driving the vacuum pump 50, it is possible to vacuum degas (exhaust) the inside of the mold 10 (inside the cavity) through the vacuum degassing pipe 15.

In addition, a resin injection pipe 16 is embedded in the mold 10 (upper mold 12 in the illustrated example) to form a gate (resin injection port) 14 that opens into the cavity. In this example, the gate 14 is disposed at a position facing the center (axial direction) of the preform 2. A resin injection machine 60 is connected to the resin injection pipe 16. Resin 6 can be injected (supplied) from the resin injection machine 60 through the resin injection pipe 16 from the gate 14 into the mold 10 (cavity). The resin 6 is, for example, a two-part thermosetting epoxy resin consisting of a base agent and a hardener. The resin injection machine 60 includes a pressure device 66, a resin reservoir 64 that stores the resin 6, which is a mixture of the base agent and the hardener, and an opening/closing valve 62 that supplies the resin 6 to the resin injection pipe 16.

In this example, a liquid nitrogen gas supply pipe 18 is embedded in the mold 10 (upper mold 12 in the illustrated example). A liquid nitrogen gas supply device 80 including a liquid nitrogen gas tank 84 equipped with a pressure regulating valve 82 is connected to the liquid nitrogen gas supply pipe 18. Liquid nitrogen gas can be pressurized and filled from the liquid nitrogen gas supply device 80 through the liquid nitrogen gas supply pipe 18 into the mold 10 (i.e., the outside of the preform 2 placed in the mold 10).

The manufacturing apparatus 1 also includes a transport mechanism 20 for transporting the preform 2 to a predetermined position, a drive mechanism 30 for driving the mold 10 (specifically, the upper mold 12) in the opening/closing direction (vertical direction) or the axial direction (horizontal direction), a temperature control device 40 for controlling the temperature of the mold 10 (lower mold 11, upper mold 12), and a control device 90 as a controller for controlling the operating state of the entire manufacturing apparatus 1 (specifically, the operating states of the transport mechanism 20, drive mechanism 30, temperature control device 40, vacuum pump 50, pressure device 66 and opening/closing valve 62 of the resin injector 60, pressure regulating valve 82 of the liquid nitrogen gas supply device 80, etc.).

[Manufacturing method of high pressure tank]
Fig. 2 is a flow chart for explaining a method for manufacturing a high-pressure tank according to an embodiment. Fig. 3 is a flow chart for explaining the adhesiveness imparting step in Fig. 2. Figs. 4 to 9 are vertical cross-sectional views respectively showing states of a preform arrangement step and a vacuum degassing step, a liquid nitrogen gas filling step in the adhesiveness imparting step, an upper die lowering step in the adhesiveness imparting step, an upper die raising step in the adhesiveness imparting step, a final tightening step and a resin injection step, a resin injection stopping step, and a resin hardening step.

(Mold preparation process: S201)
First, the mold 10 consisting of the lower mold 11 and the upper mold 12 having the above-mentioned configuration is prepared.

(Preform preparation process: S202)
As described above, the preform 2 is prepared in advance, in which the fiber layer 5 is formed by winding (wrapping) fibers around the outer surface of the hollow liner 4 .

(Mold warming process: S203)
Next, the control device 90 controls the temperature control device 40 to keep the mold 10 (the lower mold 11 and the upper mold 12) at a predetermined temperature. If the resin 6 is a thermosetting resin, the predetermined temperature is a temperature equal to or higher than the hardening temperature of the resin 6.

Here, the mold 10 is initially kept at a temperature equal to or higher than the curing temperature of the resin 6. However, for example, the mold 10 may be initially kept at a temperature lower than the curing temperature of the resin 6, and then at an appropriate timing in the process described below (for example, after the resin 6 is injected and has completely impregnated into the layers), the mold 10 may be kept at a temperature equal to or higher than the curing temperature of the resin 6.

(Preform placement process: S204)
Next, the control device 90 controls the transport mechanism 20 and the drive mechanism 30 to place the preform 2 in the mold 10 (i.e., between the lower mold 11 and the upper mold 12) (FIGS. 1 and 4). Specifically, with the upper mold 12 open, the transport mechanism 20 places the preform 2 on the lower mold 11 under the control of the control device 90. At this time, the preform 2 is supported by the shaft 25. Then, the drive mechanism 30 starts clamping under the control of the control device 90 to provisionally clamp the upper mold 12. Provisional clamping is an intermediate state between the open state and the fully clamped state, in which the lower mold 11 and the upper mold 12 are spaced apart from each other, and is moved to a position where a gap (second gap) of several mm is formed between the upper mold 12 and the preform 2, as shown in FIG. The gap (second gap) formed between the upper mold 12 and the preform 2 is larger than the gap (first gap) between the lower mold 11 and the preform 2.

(Vacuum degassing process: S205)
Next, in the above-mentioned provisionally clamped state (in other words, before the mold clamping is completed), the controller 90 controls the vacuum pump 50 to evacuate the inside of the mold 10 (FIG. 4).

(Adhesiveness imparting step: S206)
After the above-mentioned vacuum degassing is stopped (completed), the inner surface (cavity surface) of the mold 10 is given adhesiveness to the fiber layer 5 (fibers constituting the fiber layer 5) of the preform 2, and the adhesiveness is utilized to perform the Thus, gaps are formed in (between) the fiber layers 5. Here, "forming gaps in the fiber layers 5" includes increasing the gaps present in the fiber layers 5.

In this example, the adhesiveness imparting process (S206) includes a liquid nitrogen gas filling process (S2061), an upper die lowering process (S2062), and an upper die raising process (S2063), as shown in FIG. 3.

(Liquid nitrogen gas filling process: S2601)
In the above-mentioned adhesiveness imparting step (S206), first, the control device 90 opens the pressure adjusting valve 82 of the liquid nitrogen gas supply device 80, thereby pressurizing and filling the liquid nitrogen gas from the liquid nitrogen gas tank 84 into the mold 10 (FIG. 5). Since the upper mold 12 is temporarily fastened, the liquid nitrogen gas is discharged (pressurized and filled) toward the gap (second gap) formed between the upper mold 12 and the preform 2 (upper surface). This imparts adhesiveness to the fiber layer 5 of the preform 2 to the inner surface of the mold 10.

(Upper mold lowering process: S2062)
Next, the control device 90 controls the drive mechanism 30 to lower the upper mold 12 to the lower end (to approach the preform 2 relatively), and the mold 10 (the upper mold 12 and the lower mold 11) is closed. ) is then closed (FIG. 6). As a result, the fiber layer 5 of the preform 2 is brought into contact with and bonded to the inner surface of the mold 10.

(Upper die rising process: S2063)
Next, the control device 90 controls the drive mechanism 30 to raise (for example, to a provisionally fastened state) the upper die 12 (relatively move it away from the preform 2) while adhering the fiber layer 5 of the preform 2 to the inner surface of the mold 10. At this time, the control device 90 controls the drive mechanism 30 to ultrasonically vibrate the upper die 12 in the axial direction (i.e., the longitudinal direction of the preform 2) (FIG. 7). As a result, gaps are formed between the layers of the fiber layer 5 of the preform 2 attached to the inner surface of the mold 10.

At this time, in addition to or instead of the longitudinal direction of the preform 2, the upper mold 12 may be ultrasonically vibrated in the transverse direction of the preform 2 (the lamination direction or thickness direction of the fiber layer 5).

At this time, an inert gas supply pipe (not shown) may be provided to discharge an inert gas such as nitrogen gas in the longitudinal direction of the preform 2, thereby forming (enlarging) gaps in (between) the fiber layers 5 of the preform 2 attached to the inner surface of the mold 10.

It is not necessary for the fiber layer 5 of the preform 2 to remain attached to the inner surface of the mold 10 until the upper mold 12 has finished rising. As long as the fibers can be floated to form gaps in the fiber layer 5 (between the layers) of the preform 2, it is sufficient for the fiber layer 5 of the preform 2 to remain attached to the inner surface of the mold 10 until the upper mold 12 rises to a predetermined height (in other words, the fiber layer 5 of the preform 2 may peel off from the inner surface of the mold 10 when the upper mold 12 rises to a predetermined height).

(Final tightening process: S207)
Next, the control device 90 controls the drive mechanism 30 to lower the upper mold 12 to its lowering end and completely close it (bring it relatively close to the preform 2), thereby completely clamping the upper mold 12 and the lower mold 11 (finally clamping) (Figure 8).

(Resin injection process: S208)
Thereafter, the resin 6 is injected/filled into the mold 10 (FIG. 8). Specifically, the control device 90 opens the open/close valve 62, and presses the resin 6 stored in the resin reservoir 64 into the pressure device 66. As a result, the (uncured) resin 6 flows through the resin injection pipe 16 provided in the upper mold 12 and is ejected from the gate 14 (in the illustrated example, the gate is provided in the center of the preform 2). Resin 6 is injected/filled into the preform 2 and is impregnated into the laminated fiber layers 5 of the preform 2 .

(Resin injection stop step: S209)
After the resin 6 has completely impregnated the laminated fiber layers 5 of the preform 2 and the resin 6 has cured and heated, the injection of the resin 6 is stopped (FIG. 9).

(Resin curing process: S210)
After the injection of the resin 6 is stopped, the resin 6 is hardened (FIG. 9).

(Demolding process: S211)
After the resin 6 has hardened, the control device 90 controls the drive mechanism 30 to open the upper mold 12. When the hardening of the resin 6 is completed, a fiber-reinforced resin layer is formed on the outer periphery of the liner of the high-pressure tank. 8 is obtained.

The method of imparting adhesiveness to the inner surface of the mold 10 in the adhesiveness imparting step (S206) is not limited to the above-mentioned method. For example, instead of liquid nitrogen gas, the inner surface of the mold 10 may be coated with the same type of resin as the resin 6 (e.g., epoxy resin) to impart adhesiveness, or may be imparted with static electricity. In addition, when imparting adhesiveness to the inner surface of the mold 10 by static electricity, the step of lowering and raising the upper mold 12 may be omitted.

In addition, in the above method, liquid nitrogen gas is pressurized and filled into the mold 10 in a temporary fastening state with a gap (second gap) of several mm between the upper mold 12 and the preform 2. This makes it easier to supply liquid nitrogen gas almost uniformly to the entire preform 2 (top surface). However, if the liquid nitrogen gas can be supplied to the preform 2 (surface) by adjusting the pressure of the liquid nitrogen gas, there is no need to previously provide a gap (second gap) of several mm between the upper mold 12 and the preform 2, and liquid nitrogen gas may be pressurized and filled into the mold 10 with the mold 10 (lower mold 11 and upper mold 12) closed, for example.

As explained above, when manufacturing high-pressure tanks for fuel cell vehicles using RTM impregnation technology, it is difficult to apply resin pressure uniformly throughout a large, thickly laminated tank (thickly wrapped with carbon fiber) to fill, impregnate, and harden the epoxy resin, leading to reduced productivity and reduced tank performance. In addition, because the tank is made of thickly laminated carbon fiber, the innermost layer of the laminate will not be impregnated unless it is filled at high pressure, but this causes the pressure directly below the gate to become too high, leading to major quality issues such as deformation of the resin liner inside the tank and fiber displacement that lead to reduced productivity and reduced tank performance.

In this embodiment, in order to dramatically improve the resin fluidity of the laminated tank, after the mold is closed, adhesiveness is imparted to the mold surface (filling with liquid nitrogen gas, applying epoxy resin, static electricity, etc.) before resin is injected, thereby adhering the carbon fiber wound around the preform 2 and lifting it in the stacking direction, thereby securing gaps between the layers. At the same time, the upper mold 12 is subjected to ultrasonic vibrations (perpendicular to or parallel to the longitudinal direction of the tank (preform 2)), and an inert gas such as nitrogen gas is discharged in the longitudinal direction of the tank (preform 2) to form gaps between the layers.

By bonding carbon fibers to the mold surface before injecting resin to form gaps, the resin can easily penetrate into the inner layer of the fiber layer. In addition, by ultrasonically vibrating the upper mold 12 (perpendicular or parallel to the longitudinal direction of the tank (preform 2)) and discharging an inert gas such as nitrogen gas in the longitudinal direction of the tank (preform 2) to form gaps between the layers, the resin can easily penetrate into the inner layer of the fiber layer. When ultrasonically vibrating the upper mold 12, it is easier to ensure the sealing of the RTM mold by vibrating in a direction parallel to the longitudinal direction of the tank compared to vibrating in a direction perpendicular to the longitudinal direction of the tank.

Therefore, in this embodiment, when epoxy resin is impregnated using RTM impregnation technology, the entire tank can be uniformly impregnated with epoxy resin at low pressure in the stack extension direction (parallel to the longitudinal direction of the tank) and in the plate thickness direction (perpendicular to the longitudinal direction of the tank), improving the performance and stabilizing the quality of the high-pressure tank. In other words, the epoxy resin can be injected at low pressure and the resin can be uniformly impregnated, resulting in improved resin impregnation, improved tank performance, and good surface quality in the high-pressure tank. At the same time, high-speed resin filling is possible, significantly shortening the molding cycle.

In this way, according to this embodiment, by floating the fibers to form gaps between the layers of fiber layer 5, and then injecting and impregnating with resin 6, it is possible to impregnate resin 6 deep into fiber layer 5 (innermost layer) in a short time.

The above describes the embodiment of the present invention in detail using the drawings, but the specific configuration is not limited to this embodiment, and even if there are design changes, etc., within the scope of the gist of the present invention, they are included in the present invention.

1 High-pressure tank (tank) manufacturing device 2 Preform 4 Liner 5 Fiber layer 6 Resin 8 High-pressure tank (tank)
10 Mold 11 Lower mold (first mold)
12 Upper mold (second mold)
14 Gate (resin injection port)
15 Vacuum degassing pipe 16 Resin injection pipe 18 Liquid nitrogen gas supply pipe 20 Conveyor mechanism 25 Shaft 30 Drive mechanism 40 Temperature control device 50 Vacuum pump 60 Resin injection machine 80 Liquid nitrogen gas supply device 90 Control device

Claims (7)

a preform placement step of placing a preform having a fiber layer formed by winding fibers on the outer surface of a hollow liner in a mold;
an adhesiveness imparting step of imparting adhesiveness to an inner surface of the mold, and forming a gap in the fiber layer of the preform by separating a part of the mold relatively from the preform or by ultrasonically vibrating a part of the mold relatively to the preform ;
and a resin injection step of injecting resin into the mold to impregnate the fiber layer with the resin. 2. The method for manufacturing a tank according to claim 1,
A method for manufacturing a tank, characterized in that in the adhesiveness imparting step, adhesiveness is imparted to the inner surface of the mold by filling the mold with liquid nitrogen gas, applying a resin to the inner surface of the mold, or charging the inner surface of the mold with static electricity. 2. The method for manufacturing a tank according to claim 1,
a step of providing an adhesive to an inner surface of the mold, and ultrasonically vibrating a portion of the mold relative to the preform while separating the portion of the mold relatively from the preform, thereby forming a gap in the fiber layer of the preform. 4. The method for manufacturing a tank according to claim 3 ,
A method for manufacturing a tank, comprising the steps of: ultrasonically vibrating a part of the mold relatively in a longitudinal direction of the preform, thereby forming gaps in the fiber layer of the preform. 2. The method for manufacturing a tank according to claim 1 ,
A method for manufacturing a tank, wherein in the adhesion imparting step, an inert gas is discharged in a longitudinal direction of the preform to form gaps in the fiber layer of the preform. 2. The method for manufacturing a tank according to claim 1,
a step of imparting adhesiveness to an inner surface of the mold, and while separating a portion of the mold from the preform, ultrasonically vibrating the portion of the mold relative to the preform, and ejecting an inert gas in the longitudinal direction of the preform, thereby forming gaps in the fiber layer of the preform. 2. The method for manufacturing a tank according to claim 1,
The mold includes a first mold and a second mold,
In the preform placement step, the preform is placed between the first mold and the second mold so as to form a second gap between the second mold and the preform, the second gap being larger than a first gap between the first mold and the preform;
In the adhesion imparting step,
imparting adhesion to the fiber layer of the preform to an inner surface of the mold;
Bringing the second mold relatively close to the preform, thereby adhering the fiber layer of the preform to an inner surface of the second mold;
while adhering the fiber layer of the preform to the inner surface of the second mold, the second mold is relatively spaced from the preform, and the second mold is ultrasonically vibrated relative to the preform to form a gap in the fiber layer of the preform;
A method for manufacturing a tank, wherein in the resin injection step, the second mold is brought relatively close to the preform, and then the resin is injected into the metal mold.