Cans and methods for manufacturing cans

Abstract

This invention relates to cans and methods for manufacturing cans. Specifically, the invention relates to a method for manufacturing a can comprising a liner and a reinforcing layer, the reinforcing layer having a first layer and a second layer, the first layer comprising a tube fitted to the outer surface of the liner, and the second layer covering the tube, the method comprising: forming the tube by winding a first fiber-reinforced resin comprising a first fiber and a first resin onto a mandrel and thermosetting the first fiber-reinforced resin under first conditions; forming the first layer by fitting the tube to the liner; and forming the second layer by winding a second fiber-reinforced resin comprising a second fiber and a second resin onto the liner to cover the first layer and thermosetting the second fiber-reinforced resin under second conditions. The second conditions define a temperature at which the shear strength of the first resin remains above an upper limit of residual stress in the tube.

Description

Technical Field

[0001] This disclosure relates to cans and methods for manufacturing cans. Background Technology

[0002] As a method for manufacturing a can including a reinforcing layer made of fiber-reinforced resin impregnated with thermosetting resin and disposed on the outer periphery of a liner, a manufacturing method including a process of forming a tube from a prepreg and assembling the tube to the liner is known. For example, Japanese Unexamined Patent Application Publication No. 2016-223569 (JP 2016-223569 A) describes a method for manufacturing a can. In this manufacturing method, a tube (a cylindrical sheet layer) is assembled to the liner, and then fiber-reinforced resin is spirally wound onto the liner to which the tube is assembled, and the spirally wound fiber-reinforced resin is heated. Thus, a spiral layer is formed. The tube is formed, for example, by heating and thermosetting the fiber-reinforced resin wound on a mandrel different from the liner, as described in JP 2016-223569 A. Summary of the Invention

[0003] When heating occurs after spiral winding, heat is applied to the fiber-reinforced resin that forms the spiral layers, and heat is also applied to the tube. At this point, the resin contained in the tube softens again due to the heat, and the strength of the tube decreases. Therefore, the residual stress in the tube may exceed the tube's strength, causing a portion of the tube to break.

[0004] This disclosure can be implemented in the following ways.

[0005] (1) One aspect of this disclosure provides a method for manufacturing a tank comprising a liner and a reinforcing layer. The reinforcing layer has a first layer and a second layer. The first layer consists of a tube fitted to the outer surface of the liner. The second layer covers the tube. The manufacturing method includes: forming a tube by winding a first fiber-reinforced resin comprising a first fiber and a first resin onto a mandrel and thermally curing the first fiber-reinforced resin wound on the mandrel under a first heating condition; forming the first layer by fitting the tube to a liner; and forming the second layer by winding a second fiber-reinforced resin comprising a second fiber and a second resin onto the liner to cover the first layer and thermally curing the second fiber-reinforced resin wound on the liner under a second heating condition. The second heating condition includes a condition where the shear strength of the first resin contained in the first layer remains above the residual stress in the tube at an upper limit temperature. For the manufacturing method according to this aspect, when the second layer is formed by thermal curing, the shear strength of the first resin contained in the first layer remains above the residual stress in the tube. Therefore, when the second layer is formed, tube breakage due to heating is suppressed.

[0006] (2) The manufacturing method according to the above aspect may further include preparing a mandrel made of a material having the same coefficient of linear expansion as the first fiber-reinforced resin. In the manufacturing method according to this aspect, since the tube and mandrel have the same coefficient of linear expansion, they thermally expand at the same rate when the tube is formed. Therefore, compared to the case where the tube is formed using a mandrel having a different coefficient of linear expansion than the tube, the residual stress in the formed tube is reduced. Therefore, when the second layer is formed, tube breakage due to heating is suppressed.

[0007] (3) In the manufacturing method according to the above aspect, the second heating condition may include heating the second fiber-reinforcing resin wound on the lining at the curing temperature of the second resin, and the manufacturing method may further include preparing a first resin and a second resin such that, at the curing temperature of the second resin, the shear strength of the first resin contained in the first layer is higher than the residual stress in the tube. For the manufacturing method according to this aspect, the shear strength of the first resin remains higher than the residual stress in the tube at the curing temperature of the second resin. Therefore, when the second layer is formed, tube breakage due to heating is suppressed.

[0008] (4) In the manufacturing method according to the above aspect, the maximum heating temperature under the second heating condition can be lower than the maximum heating temperature under the first heating condition. According to the manufacturing method of this aspect, when the second layer is formed by thermosetting, not only when the heating temperature is constant, but also when the heating temperature changes over time, the maximum temperature applied to the tube is lower than the maximum temperature applied when the tube is formed. Therefore, when the second layer is formed, the decrease in the shear strength of the first resin is suppressed, and the breakage of the tube due to heating is suppressed.

[0009] (5) Another aspect of this disclosure provides a can. The can includes a liner and a reinforcing layer. The reinforcing layer has a first layer and a second layer. The first layer is formed by a tube fitted to the outer surface of the liner. The second layer covers the tube. The curing temperature of a first resin contained in the first layer is higher than the curing temperature of a second resin contained in the second layer. For the can according to this aspect, since the curing temperature of the first resin is higher than the curing temperature of the second resin, when the second layer is formed by thermosetting, it is possible to reduce the possibility that the shear strength of the first resin is lower than the residual stress in the tube compared to the case where the curing temperature of the first resin is lower than the curing temperature of the second resin. Therefore, when the second layer is formed, tube breakage due to heating is suppressed. Attached Figure Description

[0010] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and wherein:

[0011] Figure 1 This is a cross-sectional view showing the construction of a tank according to a first embodiment of the present disclosure;

[0012] Figure 2 This is a process diagram illustrating a method for manufacturing a can according to the first embodiment;

[0013] Figure 3 This is a graph showing the relationship between shear strength (vertical axis) and temperature (horizontal axis) in thermosetting resins, as well as the residual stress in the tube.

[0014] Figure 4 This is a graph showing the relationship between shear strength (vertical axis) and temperature (horizontal axis) in thermosetting resins, as well as the residual stress in the tube; and

[0015] Figure 5 This is a graph showing the relationship between shear strength (vertical axis) and temperature (horizontal axis) in thermosetting resins, as well as the residual stress in the tube. Detailed Implementation

[0016] A. First Embodiment

[0017] A1. Equipment Structure

[0018] Figure 1 This is a cross-sectional view illustrating the construction of a tank 100 according to a first embodiment of the present disclosure. The tank 100 is a container for storing fluids. The fluid is, for example, a gas such as hydrogen or a liquid such as liquefied natural gas (LNG). The tank 100 is used, for example, in a fuel cell or other battery installed in a fuel cell electric vehicle (FCEV). The tank 100 includes a liner 10 and a reinforcing layer 20.

[0019] Liner 10 is a hollow container. Liner 10 is made of resin or metal. Examples of resins include gas barrier resins such as nylon, polyamide, ethylene-vinyl alcohol copolymer (EVOH), polyethylene, polypropylene, epoxy resin, and polystyrene.

[0020] Liner 10 includes a straight portion 11, dome-shaped portions 12 and 13, and caps 14 and 15. The straight portion 11 has a cylindrical shape. Dome-shaped portions 12 and 13 are respectively disposed at two ends of the straight portion 11. The dome-shaped portions 12 and 13 are respectively positioned at two ends of the straight portion 11 in the direction of the axis AX of liner 10. Each of the dome-shaped portions 12 and 13 has a hemispherical shape. Cap 14 is disposed at the apex of the dome-shaped portion 12. Cap 15 is disposed at the apex of the dome-shaped portion 13. Caps 14 and 15 are made of metals such as aluminum and stainless steel. Cap 14 has a connecting hole 16 extending in the direction of the axis AX of tank 100. The connecting hole 16 serves as a flow channel when fluid is supplied to tank 100 or when fluid is removed from tank 100. Cap 15 does not have the connecting hole 16 and is sealed. Cap 15 is used during the manufacture of tank 100, for example, during centering.

[0021] The reinforcing layer 20 is a layer covering the outer surface of the liner 10. The reinforcing layer 20 enhances the strength of the liner 10. The reinforcing layer 20 has a first layer 21 and a second layer 22 in the thickness direction. In other words, the reinforcing layer 20 has a first layer 21 as an inner layer and a second layer 22 as an outer layer. Specifically, the reinforcing layer 20 has a first layer 21 and a second layer 22, the first layer 21 being formed to cover the outer side of the straight portion 11 of the liner 10, and the second layer 22 being formed to cover the exposed portions of the liner 10 other than the covers 14 and 15, and the outer side of the first layer 21.

[0022] The first layer 21 has a cylindrical appearance. The first layer 21 is formed when a component referred to as a tube (described later) is assembled to the liner 10. The tube is formed by winding a first fiber-reinforced resin around a mandrel that serves as a molding die and then thermosetting the first fiber-reinforced resin. The first fiber-reinforced resin is made by impregnating a first fiber with a first resin. Examples of the first fiber include carbon fiber, glass fiber, and aramid fiber. In particular, carbon fiber is preferably used from the perspective of strength, light weight, etc. Examples of the first resin include thermosetting resins such as phenolic resin, melamine resin, urea resin, polyamide resin, and epoxy resin.

[0023] The second layer 22 is formed by winding a second fiber-reinforced resin around the liner 10 to cover the first layer 21 and then thermosetting the second fiber-reinforced resin. Specifically, the second layer 22 is formed by winding the second fiber-reinforced resin around the outer surface of the first layer 21 and the outer surfaces of the dome-shaped portions 12, 13 and then thermosetting the second fiber-reinforced resin. The second fiber-reinforced resin is made by impregnating the second fiber with the second resin. Examples of the second fiber, like the first fiber, include carbon fiber, glass fiber, and aramid fiber. Examples of the second resin, like the first resin, include thermosetting resins such as phenolic resin, melamine resin, urea resin, polyamide resin, and epoxy resin.

[0024] A2. Manufacturing method for can 100

[0025] Figure 2 This is a process diagram illustrating a method for manufacturing a can 100 according to a first embodiment. The can 100 is manufactured in one operation. Before manufacturing the can 100, the lids 14 and 15 are attached to the liner 10.

[0026] Prepare the mandrel, first fiber-reinforced resin, second fiber-reinforced resin, and liner 10 (operation P105). The mandrel is a forming die for the tube. The mandrel has, for example, a circular cylindrical shape. In this embodiment, the mandrel is made of aluminum.

[0027] The first fiber-reinforcing resin is wound onto a mandrel (operation P110). The first fiber-reinforcing resin is wound using, for example, a filament winding method (FW method). Examples of winding types of the first fiber-reinforcing resin include ring winding, helical winding, and combinations of ring winding and helical winding. The first fiber-reinforcing resin can be laminated by multiple windings.

[0028] The wound first fiber-reinforced resin is heated and thermocured under the first heating conditions (operation P115). The first heating conditions refer to the temperature, pressure, time, etc., sufficient to cure the first fiber-reinforced resin. In the first heating conditions, the temperature may be constant or may vary over time. In the first heating conditions according to this embodiment, "temperature" refers to the temperature in the heating furnace used to heat the first fiber-reinforced resin. The first heating conditions depend on the base compound, curing agent, catalyst, etc., of the first resin contained in the first fiber-reinforced resin. The first heating conditions also depend on the desired strength of the tube. The first heating conditions include, for example, heating at the curing temperature of the first resin. In this embodiment, "curing temperature" generally refers to a selected temperature within a temperature range identified as the "molding temperature" of the resin. The curing temperature is not limited to temperatures within the aforementioned temperature range. Alternatively, temperatures exhibiting advantageous effects due to prolonged heating, even at temperatures below this temperature range, may be used as "curing temperatures." The curing temperature can be obtained, for example, by differential scanning calorimetry (DSC).

[0029] The thermosetting process in operation P115 is performed as follows: Initially, a mandrel wound with the first fiber-reinforced resin remains in the heating furnace. Subsequently, the temperature in the heating furnace is gradually increased. At this point, the upper limit temperature in the heating furnace is the temperature under the first heating condition. Due to the heat generated by the reaction, a temperature higher than estimated can be applied to the first fiber-reinforced resin. Therefore, test specimens of fiber-reinforced resin similar to the first fiber-reinforced resin are prepared in advance, tested for various heating patterns with different temperature variations, and temperature data of the test specimens are collected for each heating pattern. An appropriate temperature rise program (temperature distribution) can be determined using the collected data, and the temperature can be increased as in the case of that program. During heating, by increasing the temperature while monitoring the temperature of the first fiber-reinforced resin, overshooting due to the temperature rise of the first fiber-reinforced resin exceeding the set temperature can be prevented.

[0030] The first fiber-reinforced resin, which has been thermosetting, is pulled out from the mandrel (operation P120). Thus, a tube with a cylindrical shape is formed.

[0031] The first layer 21 is formed by assembling a tube into the liner 10 (operation P125). In this embodiment, the tube obtained by thermosetting the first fiber-reinforced resin using a mandrel as a forming mold is referred to as the tube, and the tube assembled into the liner 10 is referred to as the first layer 21. Therefore, tube and first layer 21 are interchangeable terms. When the inner diameter of the tube is larger than the outer diameter of the straight portion 11 of the liner 10, the liner 10 and the tube are brought into closer contact by applying pressure to the inside of the liner 10. On the other hand, when the inner diameter of the tube is substantially the same as or smaller than the outer diameter of the straight portion 11 of the liner 10, the liner 10 can be pre-cooled to shrink, and then the tube can be assembled into the liner 10.

[0032] The second fiber-reinforcing resin is wound onto the liner 10 (operation P130). The second fiber-reinforcing resin is wound by, for example, a filament winding method (FW method), as in, for example, the case of operation P110. Examples of winding types of the second fiber-reinforcing resin include annular winding, helical winding, and combinations of annular and helical winding. The second fiber-reinforcing resin can be laminated by multiple windings.

[0033] The wound second fiber-reinforcing resin is heated and thermocured under second heating conditions (operation P135). The second heating conditions refer to the temperature, pressure, time, etc., sufficient to cure the second fiber-reinforcing resin. In the second heating conditions according to this embodiment, "temperature" refers to the temperature in the furnace used to heat the second fiber-reinforcing resin. The second heating conditions depend on the base compound, curing agent, catalyst, etc., of the second resin contained in the second fiber-reinforcing resin. The second heating conditions also depend on the desired strength of the second layer 22. The second heating conditions include, for example, heating at the curing temperature of the second resin.

[0034] In this embodiment, the upper limit temperature in the second heating condition is the temperature at which the shear strength of the first resin remains higher than the residual stress in the tube. Such a temperature can be determined, for example, by the method described below. First, a tube for measurement is prepared by the above operations P105, P110, P115, P120. Then, the residual stress in the tube is measured. This is performed, for example, by a drilling method (compliant with ASTM E 837-13). Next, the shear strength of the first resin is measured. This is performed, for example, by a shear test compliant with JIS K7087. The shear strength measurement is performed at various temperatures. Then, the curing temperature of the second fiber-reinforced resin is measured. This is performed, for example, by a DSC method. The curing temperature of the second fiber-reinforced resin is controlled by the base compound, curing agent, catalyst, etc., contained in the second resin. Based on the measured residual stress in the tube, the shear strength of the first resin, and the curing temperature of the second fiber-reinforced resin, a temperature for heating the second fiber-reinforced resin is determined such that the shear strength of the first resin remains higher than the residual stress in the tube.

[0035] The thermosetting process in operation P135 is performed as follows: First, the lining 10 wound with the second fiber-reinforced resin is left to stand in the heating oven. Then, the temperature in the heating oven is gradually increased. The upper limit temperature in the heating oven at this point is the temperature at which the shear strength of the first resin remains above the residual stress in the tube. As described in the thermosetting of the first fiber-reinforced resin in operation P115, the second fiber-reinforced resin can also be pre-tested for various temperature change patterns, and the temperature increase procedure (temperature distribution) can be determined based on the test results. The temperature can be increased while the temperature of the second fiber-reinforced resin is monitored. By heating in this manner, the second fiber-reinforced resin is thermoset. When the second layer 22 is formed by thermosetting the second fiber-reinforced resin, Figure 1 The tank 100 shown is complete.

[0036] The reason for setting the upper limit temperature in the second heating condition as described above, which is the temperature at which the shear strength of the first resin is kept higher than the residual stress in the tube, will be described below. Figure 3 This is a graph showing the relationship between the shear strength (vertical axis) and temperature (horizontal axis) of the thermosetting resin and the residual stress in the tube. The continuous line L1 represents the relationship between the shear strength of the first resin and temperature. The continuous line L2 represents the residual stress in the tube. Temperature T0 is the temperature at which the shear strength of the first resin equals the residual stress in the tube. Therefore, when the temperature is above temperature T0, the shear strength of the first resin is lower than the residual stress in the tube, and thus tube breakage may occur.

[0037] When forming the tube, the first fiber-reinforced resin is wound around a mandrel while tension is applied via the FW method. When the first fiber-reinforced resin is thermocured, the mandrel expands due to heat. At this time, not only the tension caused by the FW method but also the force in the tension direction due to the thermal expansion of the mandrel is applied to the tube. Curing occurs under these two applied forces, thus residual stress remains in the thermocured tube. When the second fiber-reinforced resin is thermocured, heat is again applied to the tube, causing the first resin in the tube to soften as the temperature increases, and its shear strength decreases. When the temperature exceeds temperature T0 and the shear strength of the first resin is lower than the residual stress in the tube, the tube may break. Therefore, as in this embodiment, the upper limit temperature in the second heating condition is set to a temperature at which the shear strength of the first resin remains higher than the residual stress in the tube (e.g., a temperature lower than temperature T0). Therefore, when the second layer 22 is formed by thermocuring, the situation where the shear strength of the first resin is lower than the residual stress in the tube can be reduced. Therefore, when the second layer 22 is formed by thermocuring, tube breakage is suppressed.

[0038] In the manufacturing method of the can 100 according to the first embodiment described above, since the second heating condition includes a temperature at which the shear strength of the first resin, which serves as an upper limit temperature, remains higher than the temperature of the residual stress in the tube, the tube breakage is suppressed when the second layer 22 is formed by thermosetting.

[0039] B. Second Embodiment

[0040] The manufacturing method of the can 100 according to the second embodiment differs from that according to the first embodiment in that the manufacturing method includes preparing a mandrel (i.e., a forming mold for the tube) made of a material having the same coefficient of linear expansion as the first fiber-reinforced resin. This operation can be performed in operation P105. The remaining configuration of the manufacturing method of the can 100 according to the second embodiment is the same as that according to the first embodiment, and therefore its description is omitted. In this specification, "the same coefficient of linear expansion" is not limited to the case where the coefficients of linear expansion are exactly the same, and has a broad concept, including cases where the coefficients of linear expansion differ within a range of about ±10%.

[0041] Figure 4This is a graph showing the relationship between the shear strength (vertical axis) and temperature (horizontal axis) of the thermosetting resin and the residual stress in the tube. The continuous line L3 represents the relationship between the shear strength of the first resin and temperature. The dashed line L4 represents the residual stress in the tube when the tube is formed using a mandrel made of a material with a different coefficient of linear expansion than the tube (e.g., aluminum) as a molding die. The continuous line L5 represents the residual stress in the tube when the tube is formed using a mandrel made of a material with the same coefficient of linear expansion as the first fiber-reinforced resin (e.g., the first fiber-reinforced resin) as a molding die. Temperature T1 is the temperature at which the shear strength of the first resin equals the residual stress in the tube when the tube is formed using a mandrel made of a material different from the tube material as a molding die. Therefore, when the temperature is above temperature T1, the shear strength of the first resin is lower than the residual stress in the tube, and thus tube breakage may occur.

[0042] When a mandrel made of a material having the same coefficient of linear expansion as the first fiber-reinforced resin is used, the mandrel and the tube thermally expand at the same rate when the tube is formed by thermosetting. Therefore, compared to the case where a mandrel made of a material having a different coefficient of linear expansion than the tube, the residual stress in the formed tube is reduced. Therefore, it is permissible to set the temperature at which the shear strength of the first resin equals the residual stress in the tube to a temperature T2 higher than temperature T1. Thus, even at temperatures higher than temperature T1, the shear strength of the first resin remains higher than the residual stress in the tube.

[0043] Using the manufacturing method of the can 100 according to the second embodiment described above, the residual stress in the tube is reduced compared to the case where a tube is formed using a mandrel having a linear expansion coefficient different from that of the first fiber-reinforced resin. Therefore, when the second layer 22 is formed by thermosetting, the shear strength of the first resin remains higher than the residual stress in the tube, thus suppressing tube breakage due to residual stress.

[0044] C. Third Embodiment

[0045] The method of manufacturing the can 100 according to the third embodiment differs from the method of manufacturing the can 100 according to the first embodiment or the method of manufacturing the can 100 according to the second embodiment in that the second heating condition includes heating the second fiber-reinforced resin wound on the liner 10 at the curing temperature of the second resin. The method of manufacturing the can 100 according to the third embodiment differs from the method of manufacturing the can 100 according to the first embodiment or the method of manufacturing the can 100 according to the second embodiment in that operation P105 includes preparing the first resin and the second resin such that the shear strength of the first resin contained in the first layer 21 at the curing temperature of the second resin is higher than the residual stress in the tube. The remaining configuration of the method of manufacturing the can 100 according to the third embodiment is the same as that of the method of manufacturing the can 100 according to the first embodiment, and therefore its description is omitted. The method of manufacturing the can 100 according to the third embodiment can be combined with the method of manufacturing the can 100 described in the second embodiment.

[0046] Figure 5 This is a graph showing the relationship between shear strength (vertical axis) and temperature (horizontal axis) for two types of thermosetting resins, as well as the residual stress in the tube. L6 represents the relationship between the shear strength and temperature of the thermosetting resin. L7 represents the relationship between the shear strength and temperature of the high-heat-resistant thermosetting resin. L8 represents the residual stress in the tube. Temperature T3 is the temperature at which the shear strength of the thermosetting resin equals the residual stress in the tube. The properties of the cured resin can be controlled by the base compound, curing agent, catalyst, etc. contained in the resin. For example, when a tube is formed using a high-heat-resistant thermosetting resin that can maintain relatively high shear strength at high temperatures, the temperature at which the shear strength of the resin equals the residual stress in the tube can be set to a temperature T4 higher than temperature T3. Therefore, when the high-heat-resistant thermosetting resin described above is used as the first resin, even at temperatures higher than temperature T3, the shear strength of the first resin remains higher than the residual stress in the tube.

[0047] As mentioned above, the curing temperature of the resin can also be controlled by the base compounds, curing agents, catalysts, etc. contained in the resin. Therefore, by preparing a second resin with a relatively low curing temperature, the heat applied to the tube is reduced when the second layer 22 is formed.

[0048] In the manufacturing method of the can 100 according to the third embodiment described above, at the curing temperature of the second resin, the shear strength of the first resin remains higher than the residual stress in the tube. Therefore, when the second layer 22 is formed by thermosetting, tube breakage due to residual stress is suppressed.

[0049] In manufacturing the can 100, to reduce tube breakage when the second layer 22 is formed, the second layer 22 can be formed at a temperature slightly lower than the curing temperature of the second resin. However, since heating is performed at a temperature slightly below the curing temperature, the second resin requires a longer curing time compared to heating at a temperature above or equal to the curing temperature. In the manufacturing method of the can 100 according to the third embodiment, the shear strength of the first resin remains higher than the residual stress in the tube at the curing temperature of the second resin; therefore, heating is performed at the curing temperature of the second resin when forming the second layer 22. Thus, the manufacturing time of the can 100 is shortened compared to heating at a temperature slightly below the curing temperature of the second resin to reduce tube breakage.

[0050] D. Other embodiments

[0051] (D1) In the first embodiment, a mandrel made of a material having a linear expansion coefficient smaller than that of aluminum can be prepared in operation P105. In the first embodiment, the mandrel is made of aluminum. Instead of aluminum, the mandrel can be made of a selected material having a linear expansion coefficient smaller than that of aluminum. By forming the mandrel from such a material, the thermal expansion of the mandrel is suppressed when the tube is formed. Examples of such materials include SUS, Invar steel, steel, and Nobinite (registered trademark). Using this method, the thermal expansion of the mandrel is reduced during tube formation, thereby reducing the residual stress in the formed tube. Therefore, tube breakage is suppressed when the second layer 22 is formed by thermosetting.

[0052] (D2) In each of the above embodiments, the highest heating temperature in the second heating condition may be lower than the highest heating temperature in the first heating condition. For the above method, not only when the heating temperature is constant, but also when the heating temperature varies with time, the highest temperature applied to the tube when forming the second layer 22 is lower than the highest temperature applied when forming the tube. Therefore, when the second layer 22 is formed, the reduction in the shear strength of the first resin is suppressed, and tube breakage is suppressed.

[0053] (D3) In the can 100 according to the first embodiment, the curing temperature of the first resin contained in the first layer 21 can be higher than the curing temperature of the second resin contained in the second layer 22. For a can 100 constructed in this way, since the curing temperature of the first resin is higher than that of the second resin, the possibility of the shear strength of the first resin being lower than the residual stress in the tube when the second layer 22 is formed by thermosetting can be reduced compared to the case where the curing temperature of the first resin is lower than that of the second resin. Therefore, tube breakage is suppressed when the second layer 22 is formed.

[0054] (D4) In each of the above embodiments, the first layer 21 is formed to cover the outer side of the straight portion 11 of the liner 10; however, this disclosure is not limited thereto. For example, the first layer 21 may be formed to cover the outer periphery of the liner 10 other than the covers 14, 15.

[0055] This disclosure is not limited to the embodiments described above, and can be implemented in various modes without departing from the spirit of this disclosure. For example, technical features in embodiments corresponding to the technical features of the aspects described in the invention summary may be replaced or combined as needed to solve some or all of the aforementioned inconveniences or to achieve some or all of the aforementioned advantageous effects. Technical features not described as indispensable in this specification may be deleted as needed.

Claims

1. A method for manufacturing a tank, the tank comprising a liner and a reinforcement layer, the reinforcement layer having a first layer and a second layer, wherein, The first layer is formed by a pipe fitted to an outer surface of the liner, and the second layer covers the pipe, The manufacturing method is characterized by comprising: forming the pipe by winding a first fiber-reinforced resin containing first fibers and a first resin on a mandrel and heat-curing the first fiber-reinforced resin wound on the mandrel under first heating conditions, wherein the first fiber-reinforced resin is wound by a filament winding method; forming the first layer by fitting the pipe to the liner, wherein the liner is made of metal; and forming the second layer by winding a second fiber-reinforced resin containing second fibers and a second resin on the liner so as to cover the first layer and heat-curing the second fiber-reinforced resin wound on the liner under second heating conditions, wherein the second fiber-reinforced resin is wound by a filament winding method, wherein the second heating conditions include a condition in which a temperature at which a shear strength of the first resin contained in the first layer is kept higher than a residual stress in the pipe is an upper limit temperature, wherein a maximum heating temperature under the second heating conditions is lower than a maximum heating temperature under the first heating conditions.

2. The manufacturing method according to claim 1, characterized in that: the manufacturing method further includes preparing a mandrel made of a material having the same linear expansion coefficient as the first fiber-reinforced resin as the mandrel.

3. The manufacturing method according to claim 1 or 2, characterized in that: the second heating conditions include a condition of heating the second fiber-reinforced resin wound on the liner at a hardening temperature of the second resin; the manufacturing method further includes preparing the first resin and the second resin so that a shear strength of the first resin contained in the first layer is higher than a residual stress in the pipe at a hardening temperature of the second resin.

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