Tank manufacturing process comprising the winding of a resin-impregnated fiber web and tank produced by the tank manufacturing process

Abstract

Tank manufacturing process comprising a winding step of winding a resin-impregnated fiber web (9) such that a web layer (8) of the tank (1) with a predetermined thickness (T) is formed, wherein: the winding step comprises a plurality of subdivided winding steps of winding subdivided fiber webs (9) obtained by subdividing the fiber web (9) into a plurality of subdivided fiber webs with a shorter length than that required to form the web layer (8) with the predetermined thickness (T), and the second subdivided winding step or each of the second and subsequent subdivided winding steps satisfies an inequality: X>(σ·t·L) / (A·W), where X is the overlap length of an initial end of a new subdivided fiber web (9) layered overlapping onto a final end of a subdivided fiber web (9) wound in the preceding subdivided winding step, σ is the tensile stress applied to the tank (1) in its circumferential direction, t and W are the thickness and width of each subdivided fiber web (9) respectively, L is the length of a cylindrical section of the tank (1), and A is the shear strength of the resin.

Description

BACKGROUND Technical area

[0001] The present disclosure relates to a tank manufacturing process and a tank. State of the art

[0002] Inventions relating to tank manufacturing processes are conventionally known (see JP 2016-223569 A). JP 2016-223569 A discloses a process for manufacturing a tank with a liner or core, wherein the process comprises the following steps (A) to (C) (see claim 1 and the like of JP 2016-223569 A).

[0003] Step (A) is a step of winding arc- or web-shaped fibers impregnated with resin onto a mandrel with a higher stiffness than that of the core, and heating and hardening the resin to form a web layer. Step (B) is a step of withdrawing the mandrel from the web layer. Step (C) is a step of inserting the core into the web layer after step (B).

[0004] Since, according to such a manufacturing process, a resin-impregnated fiber web is wound onto a mandrel that has a higher stiffness than that of the core, the fiber web can be wound onto the mandrel with a higher tension than in a case where the fiber web is wound onto the core. Therefore, deflection or sagging of the web layer can be prevented, and thus a tank can be formed with high accuracy (see paragraph 0006 et seq. of JP 2016-223569 A).

[0005] Furthermore, US 3 879 244 A discloses a method for manufacturing a tubular structural element with a wall structure consisting of layers of a graphite fiber reinforced resin composite material in which the graphite fibers are aligned at 45 degrees (DEG) from the zero-degree longitudinal axis of the tubular element.

[0006] US Patent 2017 / 0136716A1 discloses a method for manufacturing a tank comprising a tubular body section and dome-shaped end sections formed on both sides of the body section, wherein the manufacturing method comprises forming a tubular pressed body, serving as at least a part of the body section, from a fiber-reinforced resin film by winding the fiber-reinforced resin film, which contains reinforced fibers impregnated with thermoplastic resin, several times around a circumferential surface of a core from a direction perpendicular to an axial center of the core in a state in which the thermoplastic resin is molten.

[0007] Furthermore, JP 2005-214271A discloses a fiber-reinforced pressure vessel with a shell reinforced by a fiber-reinforced composite film. The fiber-reinforced composite film, with filaments arranged in one direction and impregnated with resin, is wrapped around the shell of the vessel such that the filaments run perpendicular to an axial direction of the shell, and the resin is solidified. SUMMARY

[0008] According to the aforementioned conventional tank manufacturing process, the formation of a web layer with a predetermined thickness is carried out using a web winding process by continuously winding a fiber web, the width of which is equal to the axial length of the straight section of the core, in several dozen turns onto the mandrel along its circumferential direction.

[0009] The inventors of the present application have conducted intensive investigations and found that in a case where a fiber web is wound continuously all at once, there is a possibility that unevenly layered sections may form in the resulting web layer, such as distortion or local gaps or spaces in the fiber web, which are caused by slight fluctuations in the applied tension, very small deviations in the thickness of the fiber web, and the like.

[0010] The object of the present invention is to provide a tank manufacturing process and to provide a tank that is manufactured by the tank manufacturing process.

[0011] The object and the aforementioned problems are solved by means of a tank manufacturing method according to the invention with the features of claim 1 and by means of a tank according to the invention with the features of claim 3. An advantageous further development of the invention is the subject of dependent claim 2.

[0012] The present disclosure provides a tank manufacturing process and a tank which are capable of preventing the formation of unevenly layered sections in a web layer while ensuring the strength of the tank.

[0013] According to one embodiment of the present disclosure, a tank manufacturing process is provided, comprising a winding step of winding a resin-impregnated fiber web such that a web layer of a predetermined thickness is formed, wherein the winding step comprises a plurality of subdivided winding steps of winding subdivided fiber webs obtained by subdividing a fiber web into a plurality of subdivided fiber webs with a shorter length than that required to form the web layer of the predetermined thickness, and the second subdivided winding step, or each of the second and subsequent subdivided winding steps, satisfies an inequality: X > (σ·t·L) / (A·W), wherein an overlap length of the initial end of a new subdivided fiber web, which is layered overlapping onto the final end of the subdivided fiber web wound in the preceding subdivided winding step, is specified by X.where the tensile stress applied to the tank in its circumferential direction is given by σ, the thickness and width of each subdivided fiber web are given by t and W respectively, the length of a cylindrical section of the tank is given by L, and the shear strength of the resin forming the web layer is given by A.

[0014] The inventors of the present application have found that when a fiber web of a length sufficient to form a layer of predetermined thickness is stacked by continuous winding, there is a possibility that unevenly layered sections may form in the resulting layer, such as distortion or local gaps in the fiber web. Furthermore, the inventors of the present application have completed the invention by finding that such unevenly layered sections of the fiber web can widen with an increasing number of turns of the fiber web, thus creating indentations on the surface of the tank, such as grooves, that extend along the winding direction of the fiber web.

[0015] In the tank manufacturing process according to the aforementioned embodiment of the invention of the present application, the winding step of winding a resin-impregnated fiber web to form a web layer of a predetermined thickness comprises a plurality of subdivided winding steps as described above. Each subdivided winding step is a step of winding a subdivided fiber web obtained by subdividing a fiber web into a plurality of subdivided fiber webs with a shorter length than that required to form the web layer of the predetermined thickness, as described above.

[0016] This means that the winding step of the tank manufacturing process of the aforementioned embodiment does not involve the continuous winding of a single fiber web of the length required to form a web layer of a predetermined thickness. Rather, the fiber web is divided into a plurality of subdivided fiber webs, each shorter than the length required to form the web layer of the predetermined thickness, in order to provide a plurality of subdivided fiber webs. These subdivided fiber webs are then wound by means of a plurality of subdivided winding steps to form the web layer of the predetermined thickness. Accordingly, in each subdivided winding step, a subdivided fiber web can be wound with a more uniform tension applied to it, compared to the uneven tension that would be present in the continuous winding of a single long fiber web.

[0017] Therefore, according to the tank manufacturing process of the aforementioned embodiment, it is possible to layer divided fiber webs uniformly on top of one another and simultaneously prevent the formation of distortion or local gaps in the divided fiber webs that form the web layer, regardless of very small deviations in the thickness of the divided fiber webs and the like. Accordingly, the formation of indentations such as grooves on the surface of the tank's web layer, which run along the winding direction of the divided fiber webs, can be prevented.

[0018] Furthermore, in the tank manufacturing process of the aforementioned embodiment, in the second subdivided winding step or each of the second and subsequent subdivided winding steps, an overlap length of the initial end of a new subdivided fiber web, which is layered overlapping on the final end of the subdivided fiber web wound in the preceding subdivided winding step, satisfies the following formula (1), as described above. X>(σ⋅t⋅L) / (A⋅W)

[0019] It should be noted that the symbol X in the above formula (1) indicates the overlap length of the end and beginning of the subdivided fiber webs. The symbol σ indicates the tensile stress applied to the tank in its circumferential direction. The symbol L indicates the length of the cylindrical section of the tank along its central axis, excluding the domed sections. The symbol A indicates the shear strength of the resin forming the web layer. The symbol W indicates the width of each subdivided fiber web.

[0020] When the tank is filled with a fluid such as high-pressure gas, a tensile stress is applied to the subdivided fiber webs that form the tank's membrane layer in the circumferential direction of the tank. This assumes that the internal pressure of the tank is P. inGiven that the radius of the web layer is given by R, the thickness of the web layer is given by T, and the central angle of the cross-section of the tank along its radial direction is given by dθ, the equilibrium between forces on the cylindrical tank, which is subject to internal pressure P, can be determined. in The effect is represented by the following formula (2). Pin⋅R⋅dθ−2⋅σ⋅T⋅sin(dθ / 2)=0

[0021] If dθ is sufficiently small, an approximation can be carried out such that in the above formula (2) sin(dθ / 2)≈dθ / 2 holds. From this, the following formula (3) is derived. σ=(Pin / T)⋅R

[0022] For example, let us assume that the internal pressure P inThe tank pressure is 160 MPa, the thickness T of the web layer is 3 mm, and the radius R of the web layer is 60 mm. In such a case, a tensile stress σ applied to the web layer in its circumferential direction is calculated as 3200 MPa using the formula (3) above.

[0023] If the shear stress on the overlap section of the terminal end of the subdivided fiber web wound on the lower layer and the starting end of the subdivided fiber web wound on the upper layer is greater than the tensile stress applied to the subdivided fiber webs, then the overlap section may be considered to have sufficient shear strength. That is, provided that the following formula (4) is satisfied, the overlap section of the terminal end of the subdivided fiber web on the lower layer and the starting end of the subdivided fiber web on the upper layer may be considered to have sufficient shear strength. σ⋅t⋅L <A⋅X⋅W

[0024] In the formula (4) above, the symbol σ indicates the tensile stress applied to the tank in its circumferential direction. The symbols t and W indicate the thickness and width, respectively, of a single layer of each subdivided fiber web. The symbol L indicates the length of the cylindrical section of the tank along its central axis, excluding the domed sections. The symbol A indicates the shear strength of the resin forming the web layer. The symbol X indicates the overlap length of the end and the beginning of the subdivided fiber webs.

[0025] The left side of the above formula (4) is a tensile stress applied to the subdivided fiber webs. The right side of the above formula (4) specifies a shear stress on the overlap section of the end of the subdivided fiber web wound on the lower layer side and the beginning of the subdivided fiber web wound on top of it on the upper layer side. By rearranging the above formula (4), the above formula (1) can be obtained.

[0026] Therefore, if the above formula (1) is satisfied, the overlap section of the end end of the divided fiber web forming the web layer on the lower layer side and the beginning end of the divided fiber web wound on it on the upper layer side can possess sufficient shear strength. Therefore, according to the tank manufacturing process of the aforementioned embodiment, it is possible to ensure the strength of a tank produced by winding a plurality of divided fiber webs using a plurality of divided winding steps.

[0027] In each subdivided winding step of some embodiments of the tank manufacturing process of the aforementioned embodiment, the length of each subdivided fiber web is set to a length that allows the subdivided fiber web to be wound in one or two turns onto the tank along its circumferential direction, so that the subdivided fiber web can be stacked onto the tank in one or two layers along its radial direction. Accordingly, deviation or distortion of the subdivided fiber webs during their winding can be significantly prevented.

[0028] Another embodiment of the present disclosure is a tank comprising a web layer of a predetermined thickness, wherein the web layer comprises a plurality of subdivided fiber webs stacked on top of each other by winding onto the tank along its circumferential direction and integrated by resin, and an inequality: X>(σ·t·L) / (A·W) is satisfied, wherein an overlap length of the initial end of a subdivided fiber web on the upper layer side, which is stacked overlapping onto the final end of a subdivided fiber web wound on the lower layer side, is specified by X, the maximum tensile stress applied to the tank in its circumferential direction is specified by σ, the thickness and width of each subdivided fiber web are specified by t and W respectively, the length of the cylindrical section of the tank is specified by L, and the shear strength of the resin is specified by A.

[0029] Since the tank of the aforementioned embodiment has a web layer comprising a plurality of subdivided fiber webs, which are layered onto the tank by winding along its circumference and integrated with resin, such a tank can be manufactured using the tank manufacturing process of the aforementioned embodiment. Therefore, the formation of distortion or local gaps in the subdivided fiber webs forming the web layer can be prevented, and thus the fiber webs can be layered uniformly. Accordingly, the formation of indentations, such as grooves, on the surface of the tank's web layer, which run along the winding direction of the subdivided fiber webs, can be prevented.

[0030] Since the tank of the aforementioned embodiment also satisfies the inequality: X>(σ·t·L) / (A·W), it is possible to ensure the strength of a tank produced by winding a plurality of subdivided fiber webs, as in the tank manufacturing process of the aforementioned embodiment.

[0031] According to the tank manufacturing process and the tank of the aforementioned embodiment, it is possible to prevent the formation of unevenly layered sections in a web layer and at the same time to ensure the strength of the tank, thereby preventing the formation of indentations such as furrows that run through the winding direction of the divided fiber webs on the surface of the web layer. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic, perspective view of a tank according to an embodiment of the present disclosure; Fig. 2 is a schematic cross-sectional view along a line II-II of the in Fig. 1 illustrated tanks; Fig. Figure 3 is a schematic view showing the balance between forces on a cylindrical section of the Fig. 1 illustrated tanks; Fig. Figure 4 is a schematic view of an overlap section of in Fig. 2 illustrated subdivided fiber webs; Fig. Figure 5 is an illustrative view of a winding step of a tank manufacturing process according to an embodiment of the present disclosure; Fig. 6 is a photograph of the appearance of a web layer, which is defined by the in Fig. The 5 illustrated wrapping step was formed; Fig. Figure 7 is an illustrative view of a winding step in the conventional tank manufacturing process; Fig. Figure 8 is a cross-sectional view illustrating an example of an unevenly layered section that results when using the conventional tank manufacturing process; Fig. 9 is a photograph of the appearance of a furrow in a web layer, which is made from the in Fig. The unevenly layered section illustrated in Figure 8 results; and Fig. Figure 10 is a schematic view illustrating an example of a tank from a comparative example. DETAILED DESCRIPTION

[0032] Embodiments of a tank manufacturing process and a tank according to the present disclosure are described below with reference to the drawings.

[0033] Fig. Figure 1 is a schematic, perspective view of a tank 1 according to an embodiment of the present disclosure. The tank 1 of this embodiment is a high-pressure tank designed to store fuels for use, for example, in natural gas-powered motor vehicles or fuel cell vehicles. The tank 1 of this embodiment is suitable for applications for storing high-pressure hydrogen gas of, for example, about 70 MPa.

[0034] The tank 1 of this embodiment has, for example, hemispherical, dome-like sections 2 provided at opposite ends along the central axis 6, and a cylindrical section 3 located between the dome-like sections 2. Furthermore, the tank 1 has nozzles 4 and 5 provided at opposite ends along the central axis 6. One nozzle 4 has a through-hole 4a, which, for example, communicates with the interior of the tank 1, and the other nozzle 5 has, for example, a recessed section for attaching a shaft to support the tank 1 during its manufacture.

[0035] Fig. 2 is a schematic cross-sectional view along a line II-II of the in Fig. The tank 1 of this embodiment is, for example, a tank 1 with a multilayer structure and includes a liner or core 7, which forms the innermost layer, and a web layer 8 with a predetermined thickness T, which forms the outermost layer. Although not shown, the tank 1 can further include a fiber layer as the outermost layer and the web layer 8 as an intermediate layer between the core 7 and the fiber layer. The fiber layer can be formed, for example, by helically winding bundles of fibers made of glass fibers, carbon fibers, or the like, impregnated with resin, around the web layer 8 using a filament winding process.

[0036] The core 7, for example, is a hollow container made of resin, at the opposite ends of which, along the direction of the central axis 6, the nozzles 4 and 5 are attached. Examples of the material for forming the core 7 include, but are not limited to, thermoplastic resins such as polyethylene, nylon, polypropylene, and polyester. Examples of the material for forming the nozzles 4 and 5 include metals such as aluminum or stainless steel. It should be noted that the nozzle 5 for attaching a shaft for supporting the tank 1 can be omitted during the manufacture of the tank 1.

[0037] The web layer 8 comprises a plurality of subdivided fiber webs 9, which are layered on top of each other by winding them onto the tank 1 along its circumferential direction and integrated with resin. The number of subdivided fiber webs 9 that form the web layer 8 is a plurality, that is, any number greater than one. It should be noted that in Fig. 2 a divided fiber web 9 on the lower layer side, which is layered by winding onto the tank 1 along its circumferential direction Dc, is indicated by the solid line, a divided fiber web 9 which is wound onto it on the upper layer side is indicated by the dashed line, and a divided fiber web 9 of the third and subsequent layers is omitted.

[0038] Each subdivided fiber web 9, for example, is a fiber aggregate obtained by aligning bundles of fibers of glass fibers, carbon fibers, or the like and forming them into a web shape with a predetermined width, length, and thickness. Each of the plurality of subdivided fiber webs 9 is, for example, impregnated with liquid resin 10 and stacked by winding it in one or more turns onto the tank 1 along its circumferential direction Dc, and is then integrated by the resin 10 as a result of its curing, thereby forming the web layer 8. Examples of the resin 10 used to impregnate the plurality of subdivided fiber webs 9 so that they are integrated include thermosetting resins such as epoxy resin.

[0039] In some embodiments, the length of each divided fiber web 9 along the circumferential direction Dc of the tank 1, i.e., the winding direction, is a length that allows the divided fiber web 9 to be wound, for example, in one or two turns onto the tank 1 along its circumferential direction Dc, so that the divided fiber web 9 can be stacked in one or two layers. In the embodiment described in Fig. In the illustrated example 2, each divided fiber web 9 is wound in two turns onto the tank 1 along its circumferential direction Dc and is stacked in two layers onto the tank 1 along its radial direction. The starting end 9b of a divided fiber web 9 on the upper layer is stacked over the ending end 9e of a divided fiber web 9 wound on the lower layer by a predetermined overlap length.

[0040] The tank 1 of this embodiment satisfies the following inequality (1), wherein the overlap length of the initial end 9b of the subdivided fiber web on the upper layer side, which is stacked overlapping onto the final end 9e of the subdivided fiber web 9 wound on the lower layer side, is denoted by X, the tensile stress applied to the tank 1 in its circumferential direction Dc is denoted by σ, the thickness and width of each subdivided fiber web 9 are denoted by t and W respectively, the length of the cylindrical section 3 of the tank 1 is denoted by L, and the shear strength of the resin 10 for integrating the subdivided fiber webs 9 is denoted by A. X>(σ⋅t⋅L) / (A⋅W)

[0041] Fig. Figure 3 is a schematic view showing the balance between forces on the cylindrical section 3, which is subject to the internal pressure of the Fig. Figure 1 illustrates the process by which the tank 1 is subjected to a tensile stress in the circumferential direction Dc of the tank 1. When the tank 1 is filled with a fluid such as high-pressure hydrogen gas, a tensile stress is applied to the subdivided fiber webs 9, which form the web layer 8 of the tank 1. This assumes that the internal pressure of the tank 1 is P. in Given that the radius of the web layer 8 is given by R, the thickness of the web layer 8 is given by T, and the central angle of the cross-section of the tank 1 along its radial direction is given by dθ, the equilibrium between forces on the cylindrical section 3 of the tank 1, which is subjected to the internal pressure P, can be determined. in The effect is represented by the following formula (2). Pin⋅R⋅dθ−2⋅σ⋅T⋅sin(dθ / 2)=0

[0042] If dθ is sufficiently small here, an approximation can be carried out such that in the above formula (2) sin(d0 / 2),ztd0 / 2 holds. From this, the following formula (3) is derived. σ=(Pin / T)⋅R

[0043] For example, let us assume that the internal pressure P in The tensile strength of tank 1 is 160 MPa, the thickness T of the web layer 8 is 3 mm, and the radius R of the web layer 8 is 60 mm. In such a case, a tensile stress σ applied to the web layer 8 of tank 1 in the circumferential direction Dc is calculated as 3200 MPa using the formula (3) above. The strength of the core 7 is not taken into account.

[0044] Fig. Figure 4 is a schematic view of an overlap section 9D of the termination end 9e of the subdivided fiber web 9 wound on the lower layer side and the starting end 9b of the subdivided fiber web 9 wound on it on the upper layer side. If, in the web layer 8, the shear stress on the overlap section 9D of the termination end 9e of the subdivided fiber web 9 wound on the lower layer side and the starting end 9b of the subdivided fiber web 9 wound on it on the upper layer side is greater than the tensile stress applied to the subdivided fiber webs 9, then the overlap section 9D can be considered to have sufficient shear strength.This means that if the following formula (4) is satisfied, it can be assumed that the overlap section 9D of the termination end 9e of the subdivided fiber web 9 on the lower layer side and of the initial end 9b of the subdivided fiber web 9 on the upper layer side has sufficient shear strength. σ⋅t⋅L <A⋅X⋅W

[0045] In formula (4) above, the symbol σ represents a tensile stress applied to the tank 1 in the circumferential direction Dc and can be determined from formula (3) above. The symbols t and W represent the thickness and width, respectively, of a single layer of each subdivided fiber web 9. Furthermore, the symbol L represents the length of the cylindrical section 3 of the tank 1 along the direction of the central axis 6, excluding the dome-shaped sections 2. The symbol A represents the shear strength of the resin 10 that forms the web layer 8. The symbol X represents the overlap length of the end 9e and the beginning 9b of the subdivided fiber webs 9.

[0046] The left side of the above formula (4) specifies a tensile stress applied to the subdivided fiber webs 9. The right side of the above formula (4) specifies a shear stress on the overlap section 9D of the end 9e of the subdivided fiber web 9 wound on the lower layer side and the beginning 9b of the subdivided fiber web 9 wound on the upper layer side in the web layer 8. By rearranging the above formula (4), the above formula (1) can be obtained.

[0047] Next, a tank manufacturing process according to an embodiment of the present disclosure is described based on a comparison with the conventional tank manufacturing process.

[0048] Fig. Figure 7 is an illustration of winding step S901 of the conventional tank manufacturing process M901. For example, the conventional tank manufacturing process M901 described in JP 2016-223569 A above includes a winding step S901 of winding a resin-impregnated fiber web FS to form a web layer of a predetermined thickness T. Specifically, the conventional tank manufacturing process M901 includes a step of winding a resin-impregnated fiber web FS onto a mandrel with a higher stiffness than that of the core 907 and heating and curing the resin to form a web layer.

[0049] In winding step S901 of the conventional tank manufacturing process M901, a fiber web FS, having a width equal to the axial length of the cylindrical section of the core 907, is continuously wound in several dozen turns onto the mandrel along its circumferential direction using a web winding process, thus forming a web layer with a predetermined thickness. However, if a fiber web FS is wound continuously all at once, there is a possibility that unevenly layered sections will form in the resulting web layer, such as distortion or local gaps in the fiber web FS, caused by slight fluctuations in the applied tension, very small variations in the thickness of the fiber web FS, and the like.

[0050] Fig. Figure 8 is a cross-sectional view illustrating an example of an unevenly layered section that may result from using the conventional tank manufacturing process M901. Fig. Figure 9 is a photograph of the appearance of an exemplary groove 908c on the outer surface of a web layer 908, which is made from the in Fig. The unevenly layered section illustrated in Figure 8 results.

[0051] In the Fig. In the illustrated example 8, distortion of the fiber webs FS occurs due to slight fluctuations in the tension applied during winding step S901, very small deviations in the thickness of the fiber webs FS, and the like. This results in a local gap G between a fiber web FS wound in the second turn and a fiber web FS wound in the third turn. Consequently, a slight wave-like deflection occurs in the fiber web FS wound in the third turn. Subsequently, with an increasing number of turns of the fiber webs FS, the deflection of the fiber webs FS widens, and finally, a deep groove 908c is formed on the outer surface of the web layer 908, as shown in Fig. 9 illustrates.

[0052] Such deflection or distortion of the fiber webs FS forming the web layer 908 can reduce the strength of the web layer 908. However, if the number of turns of the fiber webs FS is increased to compensate for the decrease in the strength of the web layer 908 resulting from the deflection or distortion of the fiber webs FS forming the web layer 908, the manufacturing costs of the tank will increase. Furthermore, if a fiber web FS of a length Ls required to form the web layer 908 of a predetermined thickness is wound continuously in one go, the costs of the production plant would increase, potentially reducing productivity, if the tension is controlled with high precision or the winding speed is reduced to prevent distortion or deviation of the fiber webs FS.

[0053] In contrast, the tank manufacturing process of this embodiment includes a winding step described below. Fig. Figure 5 is an illustrative view of a tank manufacturing process M1 according to an embodiment of the present disclosure. In the tank manufacturing process M1 of this embodiment, known steps can be used for the steps that differ from the winding step S1 described below. Therefore, the description of the steps different from the winding step S1 is omitted.

[0054] The tank manufacturing process M1 of this embodiment includes a winding step S1 of winding a fiber web FS impregnated with resin 10 to form a web layer 8 with a predetermined thickness T, as in the aforementioned conventional manufacturing process M901. However, in the tank manufacturing process M1 of this embodiment, the winding step S1 has a different technical feature than that of the aforementioned conventional manufacturing process M901. Specifically, in the tank manufacturing process M1 of this embodiment, the winding step S1 includes a plurality of subdivided winding steps S11 of winding subdivided fiber webs 9, which are obtained by subdividing a fiber web FS into a plurality of subdivided fiber webs with a shorter length ls than the length Ls required to form the web layer 8 with the predetermined thickness T.

[0055] This means that the tank manufacturing process M1 of this embodiment does not continuously wind a single fiber web FS with the length Ls required to form the web layer 8 with the predetermined thickness T in the winding step S1. Rather, the fiber web FS is divided into a plurality of subdivided fiber webs, the length ls of which is shorter than the length Ls required to form the web layer 8 with the predetermined thickness T, and the subdivided fiber webs 9 are wound by means of the plurality of subdivided winding steps S11 to form the web layer 8 with the predetermined thickness T.

[0056] Accordingly, the subdivided fiber webs 9 can be wound with a more uniform tension in each of the subdivided winding steps S11, compared to the uneven tension that would be applied to them in the case of continuous winding of a single long fiber web FS. Therefore, according to the tank manufacturing method M1 of this embodiment, it is possible to stack the subdivided fiber webs 9 uniformly on top of each other and at the same time prevent the formation of distortion or local gaps in the subdivided fiber webs 9 that form the web layer 8, regardless of very small variations in the thickness of the subdivided fiber webs 9 and the like.

[0057] Fig. 6 is a photograph of the appearance of the [thing] caused by the [thing]. Fig. Figure 5 illustrates the web layer 8 formed in winding step S1. According to the tank manufacturing process M1 of this embodiment, it is possible to uniformly stack the divided fiber webs 9 on top of each other in winding step S1 and simultaneously prevent the formation of distortion or local gaps between the divided fiber webs 9, as described above. Accordingly, the formation of indentations such as grooves, which run through the winding direction of the divided fiber webs 9, on the surface of the web layer 8 of the tank 1 can be prevented, as shown in Figure 5. Fig. 6 illustrates.

[0058] Fig. Figure 10 is a schematic view illustrating an example of a Tank 901 of a comparative example, which is derived from the one in Fig. Tank 1 of this embodiment is different from the one illustrated in 2. In tank 901 of the in Fig. In the illustrated comparative example 10, the end 909e of a subdivided fiber web 909 forming a web layer 908 on the lower layer side and the beginning end 909b of a subdivided fiber web 909 wound on the upper layer side have no overlapping sections. In such a case, there is a possibility that the resistance to the tensile stress applied between the end 909e of the subdivided fiber web 909 on the lower layer side and the beginning end 909b of the subdivided fiber web 909 on the upper layer side will decrease, and thus the resistance or strength of the tank 901 may become insufficient.

[0059] In contrast, according to the tank manufacturing process M1 of this embodiment, in the second subdivided winding step S11 or each of the second and subsequent subdivided winding steps S11, in Fig. Figure 5 illustrates the stacking of the initial end 9b of a new subdivided fiber web 9, overlapping by an overlap length X, onto the final end 9e of the subdivided fiber web 9 wound in the preceding subdivided winding step S11, as shown in Fig. 2 and Fig. Figure 4 illustrates the overlap length X is set such that it satisfies the inequality (1) above.

[0060] Specifically, as in Fig. 3 illustrates, for example, let us assume that the internal pressure P in The tensile stress σ of tank 1 is 160 MPa, the thickness T of the web layer 8 is 3 mm, and the radius R on the inner surface of the web layer 8 is 60 mm. In such a case, a tensile stress σ in the circumferential direction Dc applied to the web layer 8 of tank 1 is calculated as 3200 MPa using the formula (3) above.

[0061] Furthermore, as in Fig. As illustrated in Figure 4, assume that the thickness t of a single web of each subdivided fiber web 9 is 0.1 mm, the shear strength A of resin 10, which integrates the plurality of subdivided fiber webs 9, is 20 MPa, and the length L of the cylindrical section 3 of the tank 1 is equal to the width W of each subdivided fiber web 9. In such a case, the overlap length X of the termination end 9e of the subdivided fiber web 9 on the lower layer side and the termination end 9b of the subdivided fiber web 9 wound onto it on the upper layer side is set to be greater than 16 mm, so that the above inequality (1) is satisfied. It should be noted that the majority of subdivided fiber webs 9 are wound in a total of about 30 to 40 turns onto the tank 1 along its circumferential direction Dc, so that about 30 to 40 layers are stacked onto the tank 1 along its radial direction, forming the web layer 8.

[0062] If, as described above, the overlap length X satisfies the inequality (1) above, the overlap section 9D of the termination end 9e of the subdivided fiber web 9 forming the fiber web 8 on the lower layer side and of the termination end 9b of the subdivided fiber web 9 wound onto it on the upper layer side can possess a shear strength sufficient to withstand the tensile stress σ with which the tank 1 is subjected in its circumferential direction Dc, as described above. Therefore, according to the tank manufacturing method M1 of this embodiment and the tank 1 produced by the manufacturing method M1, sufficient strength of the tank 1 with the plurality of subdivided fiber webs 9 wound onto it can be ensured.

[0063] Furthermore, in the tank manufacturing process M1 of this embodiment, in the subdivided winding step S11, the length of each subdivided fiber web 9 can be set to a length that allows the subdivided fiber web 9 to be wound in one or two turns onto the tank 1 along its circumferential direction Dc, so that the subdivided fiber web 9 can be stacked in one or two layers. Accordingly, as in Fig. As illustrated in Figure 2, each subdivided fiber web 9 is stacked by winding it in one or two turns onto the tank 1 along its circumferential direction Dc, and thus any deviation or distortion of the subdivided fiber web 9 while it is being wound can be significantly prevented.

[0064] It should be noted that in the tank manufacturing process M1 of this embodiment, after winding a plurality of divided fiber webs 9 around a mandrel and curing the resin 10 impregnating the divided fiber webs 9 to form the web layer 8 in winding step S1, it is possible to withdraw the mandrel and insert a core 7 into the web layer 8. Alternatively, in the tank manufacturing process M1 of this embodiment, a plurality of divided fiber webs 9 can be wound directly around the core 7 in winding step S1, and the resin 10 impregnating the divided fiber webs 9 can be cured to form the web layer 8.

[0065] As described above, the tank manufacturing process M1 of this embodiment includes the winding step S1 of winding a fiber web impregnated with the resin 10 such that the web layer 8 with the predetermined thickness T is formed. The winding step S1 comprises a plurality of subdivided winding steps S11 of winding subdivided fiber webs 9, which were obtained by subdividing a fiber web FS into a plurality of subdivided fiber webs with a shorter length ls than the length Ls required to form the web layer 8 with the predetermined thickness T.Furthermore, in the second winding steps S11 or each of the second and subsequent winding steps S11, provided that the overlap length of the initial end 9b of a new subdivided fiber web 9, which is stacked overlapping on the final end 9e of the subdivided fiber web 9 wound in the preceding subdivided winding step S11, is specified by X, a tensile stress in the circumferential direction Dc, with which the tank 1 is subjected, is specified by σ, the thickness and width of each subdivided fiber web 9 are specified by t and W respectively, the length of the cylindrical section 3 of the tank 1 is specified by L, and the shear strength of the resin 10 is specified by A, the above inequality (1) is satisfied, that is, X>(σ·t·L) / (A·W) is satisfied.

[0066] Furthermore, the tank 1 of this embodiment includes the web layer 8 with the predetermined thickness T. The web layer 8 is stacked by being wound onto the tank 1 along its circumferential direction Dc and comprises a plurality of subdivided fiber webs 9 integrated by the resin 10. Moreover, assuming that the overlap length of the initial end 9b of a subdivided fiber web 9 on the upper side of the layer, which overlaps the final end 9e of a subdivided fiber web 9 wound on the lower side of the layer, is specified by X, the tensile stress applied to the tank 1 in its circumferential direction Dc is specified by σ, and the thickness and width of each subdivided fiber web 9 are specified by t and σ, respectively.Given that W is specified, the length of the cylindrical section 3 of the tank 1 is specified by L, and the shear strength of the resin 10 is specified by A, the above inequality (1) is satisfied, that is, X>(σ·t·L) / (A·W) is satisfied.

[0067] According to the tank manufacturing process M1 and the tank 1 with such a configuration, it is possible to prevent the formation of unevenly layered sections in the web layer 8 while ensuring the strength of the tank 1 and thus preventing the formation of indentations such as furrows, which run through the winding direction of the subdivided fiber webs 9, on the surface of the web layer 8, as described above.

[0068] Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, specific configurations are not limited thereto, and any design modifications which are within the spirit and scope of the present disclosure are all included in the present disclosure. DESCRIPTION OF SYMBOLS 1 tank 3 cylindrical section 8th layer 9 subdivided fiber web 9b Start End 9e End of final proceedings 10 Harz A Shear strength DC circumferential direction FS fiber web L Length of the cylindrical section Ls length of the fiber web as length of the subdivided fiber web M1 Tank manufacturing process S1 winding step S11 subdivided winding step T predetermined thickness T Thickness W width X Overlap length σ Tensile stress

Claims

[1] Tank manufacturing process comprising a winding step of winding a resin-impregnated fiber web (9) such that a web layer (8) of the tank (1) with a predetermined thickness (T) is formed, wherein: the winding step comprises a plurality of subdivided winding steps of winding subdivided fiber webs (9) obtained by subdividing the fiber web (9) into a plurality of subdivided fiber webs with a shorter length than that required to form the web layer (8) with the predetermined thickness (T), and the second subdivided winding step or each of the second and subsequent subdivided winding steps satisfies an inequality: X>(σ·t·L) / (A·W), where X is the overlap length of an initial end of a new subdivided fiber web (9) layered overlapping onto a final end of a subdivided fiber web (9) wound in the preceding subdivided winding step, σ is the tensile stress applied to the tank (1) in its circumferential direction, t and W are the thickness and width of each subdivided fiber web (9) respectively, L is the length of a cylindrical section of the tank (1), and A is the shear strength of the resin. [2] Tank manufacturing method according to claim 1, wherein: In each subdivided winding step, the length of each subdivided fiber web (9) is set to a length that allows the subdivided fiber web (9) to be wound in one or two turns onto the tank (1) along its circumferential direction, so that the subdivided fiber web (9) is stacked in one or two layers. [3] Tank (1) manufactured by the tank manufacturing process according to claim 1 or 2 and comprising a web layer (8) with a predetermined thickness (T), wherein: the web layer (8) comprises a plurality of subdivided fiber webs (9) which are layered on top of each other by winding onto the tank (1) along its circumferential direction and integrated by resin, and an inequality: X>(σ·t·L) / (A·W) is satisfied, where X is the overlap length of an initial end of a divided fiber web (9) on an upper layer side, which is stacked overlapping onto a final end of a divided fiber web (9) wound on a lower layer side, the tensile stress applied to the tank (1) in its circumferential direction is σ, the thickness and width of each divided fiber web (9) are t and W respectively, the length of a cylindrical section of the tank (1) is L, and the shear strength of the resin is A.

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