METHOD FOR MANUFACTURING A CRYOGENIC TANK FOR STORING A CRYOGENIC FLUID

Abstract

Provided is a method for producing a cryogenic tank for storing a cryogenic fluid, the cryogenic tank having a structure comprising an outer shell made of a fiber-reinforced composite material, a release material made of a resin, and a liner made of a resin, which have been disposed in this order from outside. The method for producing a cryogenic tank can solve various problems in conventional production methods.　In the method for producing a cryogenic tank, the liner is produced by steps including: A) a step in which a liner resin film made of a liner-forming resin is prepared, B) a step in which the liner resin film is slit to produce liner resin tape, and C) a step in which, while a mandrel having an outer surface shape corresponding to the inner surface shape of the liner is being rotated on the axis thereof, the liner resin tape is wound, under tension, on the outer surface of the mandrel.

Description

/ 18 METHOD FOR MANUFACTURING A CRYOGENIC TANK FOR STORING A CRYOGENIC FLUID Technical Field

[001] The present description refers to a method for manufacturing a cryogenic tank for storing a cryogenic fluid. Fundamentals of the Technique

[002] In the aerospace field, a cryogenic tank for storing a cryogenic fluid is frequently used. For example, in a rocket equipped with an engine that uses liquid hydrogen as fuel, tanks are mounted to store both liquid hydrogen and liquid oxygen as an oxidant. Furthermore, the development of a hydrogen-powered aircraft, which does not emit carbon dioxide, is being promoted as part of measures to combat global warming. A tank for storing liquid hydrogen is also necessary in this field.

[003] The cryogenic tank for aerospace applications, such as the one described above, needs to be lightweight, in addition to having the basic function of storing a cryogenic fluid. To meet this demand, a tank has been proposed in which a fiber-reinforced composite material is employed as the material instead of a conventional metal (for example, see Patent Document 1).

[004] Such a tank made of fiber-reinforced composite material has a structure in which a liner made of metal or resin is bonded to the inner surface of an outer casing made of fiber-reinforced composite material. In this structure, the outer casing made of fiber-reinforced composite material functions as a structural element, and the liner made of metal or resin functions as a liquid-tight element to prevent leakage of a cryogenic fluid stored inside. It is desirable that the liner also be lightweight, and is highly Petition 870250082950, ​​dated 09 / 15 / 2025, page 11 / 41 / 18 recommends applying the lining made of resin with a specific gravity lower than that of metal.

[005] However, in a tank with such a structure, the linear expansion coefficient of the fiber-reinforced composite material that forms the outer shell is significantly smaller than that of the resin that forms the liner. Thus, when a cryogenic state is created due to filling the interior of the tank with a cryogenic fluid, the contraction of the liner with the relatively large linear expansion coefficient is limited by the outer shell with relatively small contraction. As a result, there is a possibility that a tensile stress will act on the liner and the liner will break and separate from the inner surface of the outer shell.

[006] As a measure to solve such a problem, it is conceivable that, instead of joining the outer casing made of fiber-reinforced composite material to the resin-based liner, a release agent in the form of a film or tape made of a resin is placed between them, specifically, on the inner surface of the former or on the outer surface of the latter.

[007] In the tank having a structure in which the outer casing made of fiber-reinforced composite material, the release agent made of resin, and the liner made of resin are arranged in order from the outside in this way, when a cryogenic state is created due to filling the interior with a cryogenic fluid, the outer casing and the liner contract with the respective linear expansion coefficients of each component in a state in which they are isolated from each other due to the action of the release agent. In this way, the liner is free from risk of breakage and can fully perform the function of the liquid-tight element, preventing leakage of the cryogenic fluid stored inside. Related Technical Document Petition 870250082950, ​​dated 09 / 15 / 2025, page 12 / 41 / 18 Patent Document

[008] Patent Document 1: Publication of Patent Application Unexamined Japanese No. 2006-62320 Summary of the Invention Problems to be Solved by the Invention

[009] To manufacture the tank having the structure in which the outer casing made of fiber-reinforced composite material, the release agent made of resin, and the liner made of resin are arranged in that order from the outside, as described above, the following procedure is employed. First, the resin liner is manufactured on the innermost part. Then, the release agent is placed on the outer surface of the liner. Finally, the outer casing made of fiber-reinforced composite material is formed on the outer surface of the release agent.

[0010] Among these components, the resin lining is manufactured as follows. A plurality of pieces that form the respective portions of the lining are manufactured by shaping a block of resin by mechanical processing or compression molding using molds under heating. Then, these pieces are joined by a method such as heat fusion (welding), friction welding and mixing, or adhesive bonding.

[0011] However, this method involves the following problems.

[0012] In both cases of mechanical processing and compression molding, there is a limit to the reduction in wall thickness of the manufactured parts, and a large contribution to reducing the weight of the tank is impossible.

[0013] In the case of modeling parts by chipping a block of resin through mechanical processing, a large amount of resin needs to be removed by chipping, and the removed resin is discarded. Petition 870250082950, ​​dated 09 / 15 / 2025, page 13 / 41 / 18 Therefore, the processing cost and the material cost are high.

[0014] In the case of compression molding, a plurality of molds are needed to manufacture the parts.

[0015] The material properties are discontinuous in the connecting portions between the parts.

[0016] Meanwhile, the release agent is applied by manually applying the release agent in film or tape form to the outer surface of the lining.

[0017] However, this method involves the following problems.

[0018] The state of disposition of the release agent depends on the worker's skills, and the quality is unstable.

[0019] In the case of using a release agent in tape form, it is necessary to consider the influence of an adhesive applied to the tape.

[0020] In the case of using a film-based release agent, the occurrence of wrinkles during application is inevitable and is very difficult to remove completely.

[0021] As described above, there are several problems in the method for manufacturing the tank made of fiber-reinforced composite material, including the process for manufacturing the resin liner by joining the manufactured parts by molding through chipping a block of resin or compression molding using molds and the process of manually applying the release agent in film or tape form to the outer surface of this liner.

[0022] The present description aims to provide a method for manufacturing a cryogenic tank that can solve the various problems described above in the conventional technique. Ways to Solve the Problems

[0023] To solve the problem described above, a method for manufacturing a cryogenic tank according to the present description is a Petition 870250082950, ​​dated 09 / 15 / 2025, page 14 / 41 / 18: method used to manufacture a cryogenic tank that is for storing a cryogenic fluid and has a structure in which an outer casing made of a fiber-reinforced composite material, a release agent made of a resin, and a liner made of a resin are arranged in that order from the outside. The liner is manufactured by a process that includes A) a preparation step for a resin lining film composed of the resin that forms the lining, B) a slit processing step for the lining resin film to manufacture a lining resin tape, and C) a winding step of the lining resin tape around an outer surface of a mandrel having an outer surface shape corresponding to an inner surface shape of the lining in a state in which tension is applied to the lining resin tape while the mandrel rotates around the axial center of the mandrel. Advantageous Effects of the Invention

[0024] According to the present description, the following excellent effects can be obtained.

[0025] About the manufacturing process of resin lining: The thickness of the resin lining can be reduced to a thickness corresponding to a resin film, thus making a significant contribution to reducing the weight of the tank.

[0026] Unlike the conventional technique, mechanical processing is not required, and there is no material waste. In this way, the processing cost and the material cost can be reduced to a low cost.

[0027] Unlike the conventional technique, there are no connecting portions between the parts and therefore the material properties are continuous throughout the tank.

[0028] It is not necessary to prepare a plurality of molds for the Petition 870250082950, ​​dated 09 / 15 / 2025, page 15 / 41 / 18 molding.

[0029] Regarding a process for disposing of a release agent: The release agent is applied to the outer surface of the resin lining by a machine, and thus the quality can be stabilized.

[0030] There is no risk of mixing in foreign materials, such as an adhesive.

[0031] The possibility of wrinkles occurring in the release agent is low. Brief Description of the Drawings

[0032] Figure 1 is a schematic explanatory diagram illustrating the structure of a cryogenic tank manufactured by a manufacturing method of an embodiment of the present description.

[0033] Figure 2 is a schematic explanatory diagram illustrating a manufacturing process for a resin lining in the method of manufacturing a cryogenic tank of the embodiment of the present description.

[0034] Figure 3 is a schematic explanatory diagram illustrating a disposition process for a release agent in the method for manufacturing a cryogenic tank of the embodiment of the present description.

[0035] Figure 4 is a flowchart that illustrates the entire process in the method for manufacturing a cryogenic tank of the embodiment of the present description.

[0036] Figure 5 is a flowchart illustrating the entire process in an alternative method for manufacturing a cryogenic tank of the embodiment of the present description.

[0037] Figure 6 is a flowchart that illustrates the entire process in another alternative method for manufacturing a cryogenic tank of the embodiment of the present description. Method of Carrying Out the Invention Petition 870250082950, ​​dated 09 / 15 / 2025, page 16 / 41 / 18

[0038] One embodiment of the present description is described in detail below with reference to the drawings.

[0039] Figure 1 is a schematic explanatory diagram illustrating the structure of a cryogenic tank T manufactured by a manufacturing method of the embodiment of the present description and illustrates an end surface when the cryogenic tank T is cut by a plane passing through an axial center C. The cryogenic tank T is a tank for storing a cryogenic fluid. This cryogenic fluid, for example, liquid hydrogen (temperature: -253°C), liquid nitrogen (temperature: -196°C), liquid oxygen (temperature: -183°C) and LNG (temperature: -162°C) can be supplied.

[0040] The cryogenic tank T is a hollow body of revolution having an opening O in each of the two end portions in the direction of the axial center C, and has a structure in which an outer casing S, a release element R, and a liner L are arranged in that order from the outside. The shape of the inner surface of the outer casing S is substantially the same as the shape of the outer surface of the release element R. The shape of the inner surface of the release element R is substantially the same as the shape of the outer surface of the liner L. In addition, openings O are provided for attaching a tank lid, tube, or similar. Although openings O with equal diameter are provided in both end portions in the illustrated example, they may be openings with different diameters from each other, or the opening O may be provided only in one end portion.

[0041] The outer casing S is a component that functions as a structural element of the cryogenic tank T and is composed of a fiber-reinforced composite material. As such, a fiber-reinforced composite material, for example, carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic, and fiber-reinforced plastic (FRP), Petition 870250082950, ​​dated 09 / 15 / 2025, page 17 / 41 / 18, states that aramid fiber reinforced plastic can be supplied. As a matrix resin for this fiber-reinforced composite material, a resin with a forming temperature lower than the initial melting temperature of a resin (described later) that forms the L-liner is used, or the same resin as the resin that forms the L-liner.

[0042] The L-shaped liner is a component that functions as a liquid-tight element to prevent leakage of a cryogenic fluid stored within the cryogenic tank T, and is composed of a thermoplastic resin. This resin is used to have corrosion resistance and liquid tightness against the cryogenic fluid stored in tank T within a temperature range from normal temperature to cryogenic temperature. For example, polycarbonate (PC), polyetheretherketone (PEEK), and liquid crystal polymer (LCP) resins can be used.

[0043] The release agent R is a component bonded to the inner surface of the outer casing S or to the outer surface of the liner L to prevent adhesion between the outer casing S and the liner L, and is composed of a thermoplastic resin. As such, a resin having a higher initial melting temperature than the matrix resin of the fiber-reinforced composite material that forms the outer casing S described above and the resin that forms the liner L is used. As such, for example, Teflon (registered trademark), polyimide and polyetheretherketone (PEEK) may be supplied depending on the combination with the thermoplastic resin used for the liner L.

[0044] Figure 2 is a schematic explanatory diagram illustrating a manufacturing process for the L resin lining in the method for manufacturing a cryogenic tank of the embodiment of the present description.

[0045] The process for manufacturing the L resin lining consists of four stages SL1 to SL4. Petition 870250082950, ​​dated 09 / 15 / 2025, page 18 / 41 / 18

[0046] In step SL1 (resin film preparation step), a roll FLr obtained by winding a resin film (lining resin film) FL is prepared. The resin film FL is a material that must ultimately form the lining L through each step to be described below and is composed of the resin described above.

[0047] Next, in step SL2 (slit processing step), the FLr roll of FL resin film is placed in a cutter (illustration omitted) and slit processing is performed. As a result, the FL resin film unwound from the FLr roll is cut by a plurality of cutters arranged in the direction perpendicular to the unwinding direction and becomes a plurality of TL resin tapes (lining resin tapes), each having a predetermined width. Then, the TL resin tapes are each wound onto a TLr roll. The width of the TL resin tape can be set as appropriate, depending on the shape, dimensions and the like of the L resin liner to be manufactured, and can be set to, for example, 6 mm.

[0048] Subsequently, in step SL3 (rotational lamination step), a mandrel M is prepared having an outer surface shape corresponding to the inner surface shape of the resin liner L to be manufactured. Then, while the mandrel M is rotated around its axial center CM, the resin strip TL is unwound from the roll TLr prepared in step SL2 and is wound around the outer surface of the mandrel M in a state in which tension is applied to the resin strip TL.

[0049] This step is substantially similar to filament winding (FW) forming, in which a fiber bundle (prepreg) impregnated with a resin is wound around the outer surface of a mandrel. This FW forming is a well-known method for forming a fiber-reinforced composite material, and the SL3 step described above (rotational lamination step) can be Petition 870250082950, ​​dated 09 / 15 / 2025, page 19 / 41 / 18 executed applying knowledge related to a winding pattern (examples: helical, circular and similar) and similar patterns used in FW forming.

[0050] The resin liner L is the component that must function as a liquid-tight element to prevent leakage of a cryogenic fluid stored inside. Thus, when wrapping the resin tape TL around the outer surface of the mandrel M, the resin tape TL must be wrapped so that at least parts of its width overlap each other. It is desirable that the overlap between adjacent wrapped resin tapes TL be defined as 1 / 2 the width of the resin tape TL. Furthermore, to obtain a necessary thickness of the resin liner L, resin tape TL can be additionally wrapped over a layer of resin tape TL that has already been wrapped, as needed.

[0051] After the completion of step SL3 (rotational lamination step), in step SL4 (heat treatment step), the mandrel M, in the state where the resin strip TL is wrapped around the outer surface, is placed in a heat treatment furnace (autoclave) F, and the heat treatment of the resin is performed under predetermined pressure and temperature. The pressure is adjusted to an appropriate pressure greater than atmospheric pressure. The temperature is adjusted to an appropriate temperature equal to or greater than the initial melting temperature of the resin. Through the execution of the heat treatment, the resin strip TL wrapped around the outer surface of the mandrel M becomes monolithic through fusion bonding, and the resin liner L is completed.

[0052] After the resin lining L is completed through the process consisting of the four steps SL1 to SL4 described above, the release agent R is then applied to the outer surface of this resin lining L. This is described below.

[0053] Figure 3 is a schematic explanatory diagram that illustrates Petition 870250082950, ​​dated 09 / 15 / 2025, page 20 / 41 / 18 a disposition process for the release agent R in the method for manufacturing a cryogenic tank of the embodiment of the present description.

[0054] In a step SR1 (resin film preparation step), a roll FRr obtained by winding a resin film (release element resin film) FR is prepared. The resin film FR is a material that must ultimately form the release element R through each step to be described below and is composed of the resin described above.

[0055] Next, in an SR2 step (slit processing step), the FRr roll of FR resin film is placed in a cutter (illustration omitted) and slit processing is performed. As a result, the FR resin film unwound from the FRr roll is cut by a plurality of cutters arranged in the direction perpendicular to the unwinding direction and becomes a plurality of TR resin tapes (release element resin tapes), each having a predetermined width. Then, the TR resin tapes are each wound onto a TRr roll. The width of the TR resin tape can be defined as appropriate, depending on the shape, dimensions, and the like of the L resin liner completed through the process described in Figure 2.

[0056] Subsequently, in a step SR3 (rotational lamination step), while the resin liner L has been completed through the process described in Figure 2 and is rotated around its axial center CL, the resin tape TR is unwound from the roll TRr prepared in step SR2 and is wrapped around the outer surface of the resin liner L in a state in which tension is applied to the resin tape TR. This completes the release element R.

[0057] Similar to step SL3 (rotational lamination step) in the L resin lining manufacturing process, this step is also substantially similar to FW forming and can be performed by applying the knowledge used in FW forming. To obtain a required thickness of the release element R, the TR resin strip can be Petition 870250082950, ​​dated 09 / 15 / 2025, page 21 / 41 / 18 additionally wrapped over a layer of TR resin tape that has already been wrapped, as needed.

[0058] The manufacturing process for the resin liner L described with reference to Figure 2 is a process designed based on the assumption that the resin liner L is completed on its own. However, in the manufacture of the cryogenic tank having a structure in which the outer shell made of fiber-reinforced composite material, the release element made of resin, and the liner made of resin are arranged in that order from the outside, it is efficient to perform the arrangement process for the release element R after the manufacturing process for the resin liner L and additionally perform a forming process for the outer shell after the arrangement process.

[0059] The entire process of such a method for manufacturing a cryogenic tank is illustrated in Figure 4.

[0060] In Figure 4, SF denotes a forming step of the outer shell S made of fiber-reinforced composite material on the outer surface of the release element R. This step can be performed using any method publicly known as a method for forming a fiber-reinforced composite material.

[0061] In the manufacturing method illustrated in Figure 4, after step SL3 (rotational lamination step) in the resin lining manufacturing process L is completed, step SR3 (rotational lamination step) in the release agent placement process R is subsequently performed. Then, step SL4 (heat treatment step) is performed.

[0062] It is efficient to simultaneously perform the SL1 step (resin film preparation step) and the SL2 step (slit processing step) in the L resin lining manufacturing process and the SR1 step (resin film preparation step) and the SR2 step (slit processing step) Petition 870250082950, ​​dated 09 / 15 / 2025, page 22 / 41 / 18 slit) in the process of disposing of the release agent R before the SL3 stage (rotational rolling stage) and the SR3 stage (rotational rolling stage), respectively, as illustrated in the diagram.

[0063] The reason why the SR3 step (rotational lamination step) in the mold release element R disposal process is performed after the SL3 step (rotational lamination step) in the resin lining L manufacturing process without performing the SL4 step (heat treatment step) as described above is as follows.

[0064] In step SL4 (heat treatment step) in the manufacturing process of resin liner L, the mandrel M, in the state where the resin tape TL is wrapped around the outer surface, is placed in autoclave F in a state where the mandrel M is wrapped in a material such as a breathable cloth or a pocketing film. Then, pocketing (under vacuum) is performed for heat treatment. This is a measure to release the air that has entered the resin tape layer TL (and the space between this layer and the mandrel M). However, there is a possibility that wrinkles generated on the inner surface of the material described above may be transferred to the outer surface of the resin tape TL in direct contact with the material.

[0065] In contrast, when the SR3 step (rotational lamination step) in the mold release element R disposal process is performed after the SL3 step (rotational lamination step) in the resin liner L manufacturing process, a state is created in which the outer surface of the resin tape TL is covered by a layer of resin tape TR. When the SL4 step (heat treatment step) is performed in this state, the resin tape TR layer serves as part of a pocketing material, and the pocketing is enabled with a configuration in which wrinkles do not occur or are less likely to occur. This allows the manufacture of resin liner L having a smooth outer surface. Petition 870250082950, ​​dated 09 / 15 / 2025, page 23 / 41 / 18

[0066] When there is no risk of wrinkle transfer from the inner surface of the pocketing material to the outer surface of the resin tape TL, as illustrated in Figure 5, step SL4 (heat treatment step) can be performed after step SL3 (rotational lamination step) in the resin liner manufacturing process L and, subsequently, step SR3 (rotational lamination step) in the release agent disposition process R and the subsequent step can be performed.

[0067] In this case as well, it is efficient to perform the SR1 step (resin film preparation step) and the SR2 step (slit processing step) in the release agent R disposal process simultaneously with the SL1 step (resin film preparation step) and the SL2 step (slit processing step) in the resin liner L manufacturing process.

[0068] Furthermore, when the matrix resin of the fiber-reinforced composite material forming the outer shell S is the same as the resin forming the liner L, a process illustrated in Figure 6 can be employed. Specifically, in this process, the SR3 step (rotational lamination step) in the mold release element R disposal step is performed after the SL3 step (rotational lamination step) in the resin liner L manufacturing process. Subsequently, in an SF' step (outer shell lamination step), the fiber-reinforced composite material forming the outer shell S is laminated off the resin tape TR layer by any publicly known method. Then, the SL4 step (heat treatment step) is performed. This prevents the transfer of wrinkles to the outer surface of the resin tape TL attributed to wrinkles in the pocketing material, and can manufacture the resin liner L having a smooth outer surface.Furthermore, the number of times the heat treatment step is performed is reduced to a minimum. As the publicly known method applied in the SF' step (lamination step of the...) Petition 870250082950, ​​dated 09 / 15 / 2025, page 24 / 41 / 18 outer casing), for example, a filament winding (FW) method, an automated fiber positioning (AFP) method and manual lamination can be provided.

[0069] In this case as well, it is efficient to perform the SR1 step (resin film preparation step) and the SR2 step (slit processing step) in the release agent R disposal process simultaneously with the SL1 step (resin film preparation step) and the SL2 step (slit processing step) in the resin liner L manufacturing process.

[0070] According to the manufacturing method of a cryogenic tank of the embodiment of the present description described above, the following technical effects can be obtained in relation to the manufacturing process of the resin lining described with reference to Figure 2.

[0071] The thickness of the resin liner can be reduced to a thickness corresponding to a resin film, and thus a large contribution to reducing the weight of the tank can be made.

[0072] Unlike the conventional technique, mechanical processing is not required, and there is no material waste. In this way, the processing cost and the material cost can be reduced to a low cost.

[0073] Unlike the conventional technique, there are no connecting portions between the parts and therefore the material properties are continuous throughout the tank.

[0074] It is not necessary to prepare a plurality of molds for molding.

[0075] In addition, the following technical effects can be obtained in relation to the process of disposing of the release agent described with reference to Figure 3.

[0076] The release agent is placed on the outer surface of Petition 870250082950, ​​dated 09 / 15 / 2025, page 25 / 41 / 18 resin lining by machine, and thus the quality can be stabilized.

[0077] There is no risk of mixing foreign materials, such as an adhesive.

[0078] The possibility of wrinkles occurring in the release agent is low and there is a reduction effect on the transfer of wrinkles to the resin lining. (Aspects of the Present Description)

[0079] A method for manufacturing a cryogenic tank according to a first aspect of the present description is a method used to manufacture a cryogenic tank that is for storing a cryogenic fluid and has a structure in which an outer casing made of a fiber-reinforced composite material, a release agent made of a resin, and a liner made of a resin are arranged in that order from the outside. The liner is manufactured by a process that includes A) a preparation step for a resin lining film composed of the resin that forms the lining, B) a slit processing step for the lining resin film to manufacture a lining resin tape, and C) a winding step of the lining resin tape around an outer surface of a mandrel having an outer surface shape corresponding to an inner surface shape of the lining in a state in which tension is applied to the lining resin tape while the mandrel rotates around the axial center of the mandrel.

[0080] In the method for manufacturing a cryogenic tank according to a second aspect of the present description, the release agent is manufactured by a process that includes a) a preparation step for a mold release resin film composed of the resin that forms the mold release element, b) a slit processing execution step for the Petition 870250082950, ​​dated 09 / 15 / 2025, page 26 / 41 / 18 resin film for mold release element to manufacture a resin tape for mold release element, and c) a winding step of the release element resin tape around an outer surface of the liner resin tape in a state in which tension is applied to the release element resin tape while rotating the mandrel in a state in which the liner resin tape is wound around the outer surface of the mandrel around the axial center of the mandrel.

[0081] In the method for manufacturing a cryogenic tank according to a third aspect of the present description, step c) is performed after step C) and, after step c), a step of placing the mandrel in a heat treatment furnace in a state in which the lining resin tape and the release element resin tape are wrapped around the outer surface of the mandrel and performing the heat treatment to cause bonding fusion of the resin of the lining resin tape is performed.

[0082] In the method for manufacturing a cryogenic tank according to a fourth aspect of the present description, subsequent to step C), a step of placing the mandrel in a heat treatment furnace in a state in which the resin lining tape is wrapped around the outer surface of the mandrel and performing the heat treatment to cause bonding fusion of the resin of the resin lining tape is performed, and subsequently step c) is performed.

[0083] In the method for manufacturing a cryogenic tank according to a fifth aspect of the present description, step c) is performed after step C) and, after step c), the fiber-reinforced composite material is laminated onto an outer surface of the resin strip of the release element, and a step of placing, in a heat treatment oven, the mandrel in a state in which the lining resin strip, the strip of Petition 870250082950, ​​dated 09 / 15 / 2025, page 27 / 41 / 18: the resin release agent and the fiber-reinforced composite material are wrapped around the outer surface of the mandrel, and heat treatment is performed to cause the bonding fusion of the resin of each of the resin liner strip and the fiber-reinforced composite material. Explanation of Reference Signs

[0084] FL resin lining film FR release element resin film L lining M mandrel R release agent S outer casing Cryogenic tank TL resin lining tape TR release element resin tape Petition 870250082950, ​​dated 09 / 15 / 2025, page 28 / 41

Claims

1 / 3 CLAIMS 1. Method for manufacturing a cryogenic tank for storing a cryogenic fluid, characterized in that the cryogenic tank has a structure in which an outer casing made of a fiber-reinforced composite material, a release element made of a resin, and a liner made of a resin are arranged in that order from the outside, wherein the liner is manufactured by a process that includes A) a step of preparing a liner resin film composed of the resin that forms the liner, B) a step of performing slit processing for the liner resin film to manufacture a liner resin tape, and C) a step of winding the liner resin tape around an outer surface of a mandrel having an outer surface shape corresponding to an inner surface shape of the liner in a state in which tension is applied to the liner resin tape while rotating the mandrel around an axial center of the mandrel.

2. Method according to claim 1, characterized in that the release element is manufactured by a process that includes a) a step of preparing a release element resin film composed of the resin that forms the release element, b) a step of performing a slit processing for the release element resin film to manufacture a release element resin tape, and c) a step of winding the release element resin tape around an outer surface of the liner resin tape in a state in which tension is applied to the release element resin tape while rotating the mandrel in a state in which the liner resin tape is wound around the outer surface of the mandrel around the axial center of the mandrel.

3. Method according to claim 2, characterized in that step c) is performed after step c), and after step c), a step of placing the mandrel in a heat treatment furnace in a state in which the lining resin tape and the mold release element resin tape are wrapped around the outer surface of the mandrel and performing the heat treatment to cause bonding fusion of the resin of the lining resin tape is performed.

4. Method according to claim 2, characterized in that subsequent to step C), a step of placing the mandrel in a heat treatment furnace in a state in which the resin lining tape is wrapped around the outer surface of the mandrel and performing the heat treatment to cause fusion of the resin bond of the resin lining tape is performed, and subsequently step c) is performed.

5. Method according to claim 2, characterized in that step c) is performed after step c), after step c), the fiber-reinforced composite material is laminated onto an outer surface of the demolding element resin tape, and a step of placing, in a heat treatment furnace, the mandrel in a state in which the lining resin tape, the demolding element resin tape and the fiber-reinforced composite material are wrapped around the outer surface of the mandrel and performing the heat treatment to cause bonding fusion of the resin of each of the lining resin tape and the fiber-reinforced composite material is performed.

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