JP7235411B2 - High-pressure tank manufacturing method - Google Patents

Description

The present invention relates to a high-pressure tank manufacturing method for forming a fiber reinforced resin layer on the outer surface of the liner by supplying fiber bundles from a plurality of guide members arranged around the liner to the outer surface of the liner.

Conventionally, for example, a high-pressure tank is known that includes a liner for keeping hydrogen gas airtight and a fiber reinforced resin layer that is reinforced by winding a fiber bundle made of fiber reinforced resin around the outer surface of the liner. As a method for forming a fiber-reinforced resin layer, a so-called filament winding method of winding a fiber bundle around the outer surface of a liner is widely used.

In addition, in order to shorten the formation time of the fiber reinforced resin layer, a plurality of guide members are arranged around the liner, and fiber bundles are supplied from the plurality of guide members to the outer surface of the liner to form the fiber reinforced resin layer. It has been known.

By the way, the fiber-reinforced resin layer is generally composed of a hoop layer obtained by hoop-winding a fiber bundle around the cylindrical portion of the liner and a helical layer obtained by helically winding the fiber bundle around the entire liner. The helical layer is formed by feeding fiber bundles from a guide member while reciprocating the liner along its central axis and rotating about the central axis. When the helical layer is formed using a plurality of guide members as described above, while the liner makes one reciprocation along the central axis, the fiber bundle F1 of the first reciprocation moves in the circumferential direction as shown in FIG. , and when the liner makes one round trip (second round trip), the fiber bundle F2 of the second round trip is arranged between the fiber bundles F1 of the first round trip.

At this time, as shown in FIG. 10(b), when a gap is formed between the fiber bundle F1 of the first reciprocation and the fiber bundle F2 of the second reciprocation, the next time the liner makes one reciprocation (3 In the second round trip), the portion of the fiber bundle F3 of the third round trip that intersects the gap is bridged between the fiber bundle F1 of the first round trip and the fiber bundle F2 of the second round trip. A gap sandwiched between the liner and the fiber bundle F3 for the third round is formed between the bundle F1 and the fiber bundle F2 for the second round. These voids cause voids in the fiber-reinforced resin layer.

In order to improve this inconvenience, for example, in Patent Document 1, another fiber bundle (hereinafter referred to as a second fiber bundle) is arranged between previously formed fiber bundles (hereinafter referred to as a first fiber bundle). However, a method of widening the width of the second fiber bundle is described by rocking the second fiber bundle in the circumferential direction. In this method, by widening the width of the second fiber bundle, it is possible to suppress the occurrence of a gap between the second fiber bundle and the first fiber bundle to some extent.

JP 2015-217527 A

However, in the method of Patent Document 1, the second fiber bundles are arranged between the first fiber bundles while being swung in the circumferential direction. It may be arranged adjacent to one of the first fiber bundles or may be arranged adjacent to the other. For this reason, it is difficult to suppress the formation of a gap between the second fiber bundle and the first fiber bundle. is arranged, it is difficult to suppress the formation of voids in the fiber reinforced resin layer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a high-pressure tank capable of suppressing formation of voids in a fiber-reinforced resin layer.

In a method for manufacturing a high-pressure tank according to the present invention, a liner having a cylindrical cylindrical portion and dome portions provided at both ends of the cylindrical portion is provided at equal intervals around the liner around the central axis of the liner. A high-pressure tank manufacturing method for forming one or more helical layers made of fiber-reinforced resin so as to cover the cylindrical portion and the pair of dome portions by supplying fiber bundles from a plurality of guide members arranged in , the liner is reciprocated M times (where M is an integer equal to or greater than 2) along the central axis in forming one helical layer so as to cover the periphery of the tubular portion in the circumferential direction without gaps, and The liner is rotated by α° per reciprocation, the fiber bundle is supplied from n guide members (where n is an integer of 2 or more), the helical layer is formed on the liner, and the number of reciprocations of the liner is M. , the rotation angle α per reciprocation of the liner, the number n of the guide members, and k (where k is an integer) satisfy the following formula (1).
α=360/(n×M)+(360/n)×k (1)

According to the high-pressure tank manufacturing method of the present invention, while the liner reciprocates once along the central axis, the fiber bundles of the first reciprocation are arranged at predetermined intervals in the circumferential direction. Here, the number of reciprocations M of the liner, the rotation angle α per one reciprocation of the liner, the number n of the guide members, and k (where k is an integer) satisfy the above formula (1).

Since n×M is the total number of fiber bundles passing through the cylindrical portion in a predetermined direction when one helical layer is formed so as to cover the circumference of the cylindrical portion in the circumferential direction without gaps, 360/(n×M) is the pitch (angle) in the circumferential direction of the fiber bundles forming one helical layer. Assuming that the rotation angle per one round trip of the liner is 360/(n×M), each time the liner makes one round trip, the fiber bundle is wound by the same guide member the previous time (during the previous round trip). It is arranged in a part that is moved by one bundle (one pitch) in the circumferential direction from the part. In other words, the fiber bundles are arranged continuously in the circumferential direction (that is, sequentially so as to contact one side end of the same fiber bundle) without gaps with respect to the previously wound fiber bundle.

360/n is the circumferential pitch (angle) of the plurality of guide members. Therefore, if the liner rotates (360/n)×k per reciprocation, the portion of the liner that faces the guide members (the portion where the fiber bundle is arranged) is positioned to face any of the guide members. The fiber bundles are always wound on the same portion of the liner.

In the high-pressure tank manufacturing method of the present invention, the rotation angle α per one reciprocation of the liner is 360/(n×M)+(360/n)×k. are sequentially arranged so as to contact one side end of the previously arranged fiber bundle.

Therefore, when the liner makes one reciprocation after one reciprocation (second reciprocation), the fiber bundle of the second reciprocation is placed in contact with one side end of the fiber bundle of the first reciprocation. When the liner next makes one round trip (third round trip), the fiber bundle of the third round trip is placed in contact with one side end of the fiber bundle of the second round trip. In this way, since the fiber bundles are arranged in contact with one side end of the previously arranged fiber bundle, the gap between the fiber bundles in the first round trip is filled up. Then, the M-th round trip fiber bundle is arranged so that no gap is formed between the M-1 round trip fiber bundle and the 1st round trip fiber bundle.

In this way, between the fiber bundles of the first reciprocation, on one side (one side end side), the fiber bundles are arranged in contact with each other, so that a gap is formed between the fiber bundles. is suppressed. As a result, for example, it is possible to prevent the fiber bundles after the third round trip from being bridged with the previously arranged fiber bundles.

Further, between the fiber bundles of the first round trip, the gap between the fiber bundles becomes larger on the other side. As a result, for example, the fiber bundles after the third reciprocation do not bridge the previously arranged fiber bundles, but hang down to fill the gap.

In this way, between the fiber bundles of the first round trip, both the one-side portion and the other-side portion suppress the fiber bundle from being bridged with the previously arranged fiber bundle. Therefore, it is possible to suppress the formation of voids in the fiber-reinforced resin layer.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the high pressure tank which can suppress that a space|gap arises in a fiber reinforced resin layer can be provided.

1 is a cross-sectional view showing the structure of a high-pressure tank manufactured by a manufacturing method according to one embodiment of the present invention; FIG. FIG. 4 is a side view for explaining a method of manufacturing a high-pressure tank according to one embodiment of the present invention; It is a figure for demonstrating the manufacturing method of the high pressure tank which concerns on one Embodiment of this invention. FIG. 4A is a view for explaining a method of manufacturing a high pressure tank according to an embodiment of the present invention, FIG. FIG. 4(b) is a cross-sectional view taken along the arrow A1--A1 in FIG. 4(a). FIG. 5A is a view for explaining a method of manufacturing a high-pressure tank according to an embodiment of the present invention, FIG. FIG. 5(b) is a cross-sectional view taken along the arrow A2-A2 in FIG. 5(a). FIG. 4 is a diagram showing the relationship between the number of reciprocations of the liner and the relative angle around the central axis between the predetermined position of the liner and each guide member in the example. FIG. 4 is a diagram showing cutting positions A to J of high-pressure tanks of Examples and Comparative Examples. FIG. 4 is a diagram showing the void fraction at each position A to J in the example and the average value of the void fraction; FIG. 10 is a diagram showing the void fraction at each position A to J in a comparative example and the average value of the void fraction; Fig. 10(a) is a diagram for explaining a method of manufacturing a high-pressure tank according to a conventional example. ) is a cross-sectional view taken along the arrow A3-A3 in FIG. 10(a).

A method of manufacturing a high-pressure tank 10 according to an embodiment of the present invention will be described below with reference to the drawings. Before that, the structure of the high-pressure tank 10 will be briefly described. Although the high-pressure tank 10 will be described below as a tank filled with high-pressure hydrogen gas mounted on a fuel cell vehicle, it can also be applied to other uses. Further, the gas that can be filled in the high-pressure tank 10 is not limited to hydrogen gas.

As shown in FIG. 1, the high-pressure tank 10 is a substantially cylindrical high-pressure gas storage container with dome-shaped rounded ends. The high pressure tank 10 includes a liner 11 having gas barrier properties and a fiber reinforced resin layer 12 made of fiber reinforced resin covering the outer surface of the liner 11 . Openings are formed at both ends of the high-pressure tank 10 .

The liner 11 is a member made of resin that forms an accommodation space 17 filled with high-pressure hydrogen gas. In general, the liner 11 is made of thermoplastic resin that can be processed into a substantially cylindrical shape or the like. The resin that constitutes the liner 11 is preferably a resin that has good performance in retaining the filled gas (here, hydrogen gas) in the housing space 17, that is, good gas barrier properties. Examples of such resins include thermoplastic resins such as polyamide, polyethylene, ethylene-vinyl alcohol copolymer resin (EVOH), and polyester.

The liner 11 is composed of a cylindrical tubular portion 11a and a pair of dome portions 11b provided at both ends of the tubular portion 11a. A pair of dome portions 11b of the liner 11 are formed with openings, and are provided with bases 14 and end bosses 16, respectively.

The base 14 is formed by processing a metal material such as aluminum or an aluminum alloy into a predetermined shape. A valve (not shown) for charging and discharging hydrogen gas to and from the housing space 17 is attached to the mouthpiece 14 .

The end boss 16 is formed by processing a metal material such as aluminum or an aluminum alloy into a predetermined shape. The end boss 16 is a member for attaching a shaft that rotates the liner 11 when forming the fiber reinforced resin layer 12 . The shaft is attached not only to the end boss 16 but also to the mouthpiece 14 .

The fiber-reinforced resin layer 12 covers the outer surface of the liner 11 and has the function of reinforcing the liner 11 to improve mechanical strength such as rigidity and pressure resistance of the high-pressure tank 10 . The fiber-reinforced resin layer 12 is composed of a thermosetting resin and reinforcing fibers. Thermosetting resins such as phenol resins, melamine resins, urea resins, and epoxy resins are preferably used as thermosetting resins, and epoxy resins are particularly preferred from the viewpoint of mechanical strength and the like. Glass fiber, aramid fiber, boron fiber, carbon fiber, and the like can be used as the reinforcing fiber, and it is particularly preferable to use carbon fiber from the viewpoint of lightness, mechanical strength, and the like.

Generally, an epoxy resin is a resin obtained by mixing a prepolymer such as a copolymer of bisphenol A and epichlorohydrin with a curing agent such as polyamine and then thermally curing the mixture. Epoxy resin has fluidity in an uncured state and forms a strong crosslinked structure after thermal curing.

The fiber-reinforced resin layer 12 is formed by winding a bundle of fibers (for example, carbon fiber) impregnated with uncured resin (for example, epoxy resin) around the outer surface of the liner 11 and curing the resin. For example, a shaft is attached to the mouthpiece 14 and the end boss 16 of the liner 11 and rotatably supported, and a fiber bundle impregnated with resin is wound by both helical winding and hoop winding while rotating. Then, the resin component is cured by heating at the curing temperature of the resin. By using both helical winding and hoop winding, mechanical strength such as pressure resistance can be ensured in the axial direction and radial direction of the high-pressure tank 10 . The hoop winding means that the liner 11 is circumferentially wound around the outer periphery of the tubular portion 11a at an angle substantially orthogonal to the axial direction of the tubular portion 11a. On the other hand, helical winding refers to winding so as to cover the entire liner 11, that is, over a pair of dome portions 11b, at a predetermined angle (for example, 45 degrees or less) with respect to the axial direction of the cylindrical portion 11a. .

Next, a method for manufacturing the high-pressure tank 10 according to one embodiment of the present invention will be described. The method for manufacturing the high-pressure tank 10 includes a winding step of winding a fiber bundle impregnated with an uncured resin around the liner 11 and a heating step of heating and curing the fiber bundle. In the winding process, the fiber bundle is wound around the liner 11 using both helical winding and hoop winding. Here, helical winding among the methods of manufacturing the high-pressure tank 10 will be described in detail.

In the winding process, as shown in FIG. 2, shafts 30 and 31 are attached to mouthpiece 14 and end boss 16 of liner 11, respectively. Shafts 30 and 31 are rotatable and axially movable by a shaft drive mechanism (not shown). As shafts 30 and 31 rotate and move axially, liner 11 also rotates and moves axially.

As shown in FIGS. 2 and 3, a plurality of (here, nine) guide members 40 for supplying the fiber bundles F to the liner 11 are arranged around the liner 11 . The plurality of guide members 40 are arranged at equal intervals (here, at intervals of 40°) centering on the central axis L of the liner 11 . Also, the plurality of guide members 40 are held by a guide holding mechanism (not shown).

When the fiber bundle F is wound around the liner 11, the liner 11 is rotated at a predetermined speed and axially moved by the shafts 30 and 31, thereby pulling out the fiber bundle F from the bobbin (not shown). The fiber bundle F is wound around the liner 11 by a plurality of guide members 40 . By winding the fiber bundle F around the liner 11 using a plurality of guide members 40 in this way, the winding time can be shortened compared to the case where only one guide member 40 is used. Further, the liner 11 is rotated around the central axis L while reciprocating the liner 11 along the central axis L. As a result, the fiber bundle F is wound around the outer surface of the liner 11 while being inclined at a predetermined angle with respect to the central axis L. As shown in FIG.

When one helical layer is formed by helically winding the fiber bundles F around the liner 11, the fiber bundles F are wound around the cylindrical portion 11a so that no gap is formed between the adjacent fiber bundles F. That is, by forming one helical layer, the periphery of the cylindrical portion 11a is covered with the fiber bundle without gaps.

As shown in FIGS. 4 and 5, in the cylindrical portion 11a, the fiber bundles F1 of the first reciprocation are arranged in parallel with the adjacent fiber bundles F1 at a predetermined interval. 4 and 5, for the sake of simplification of the drawings, it is illustrated that one helical layer is formed by winding the fiber bundle F for four reciprocations.

Here, in the present embodiment, the fiber bundle F2 in the second round trip is in contact with the fiber bundle F1 in the first round trip, that is, in a state where it overlaps the end of the fiber bundle F1 in the first round trip, or It is arranged in contact with the end face of the fiber bundle F1. 4 and 5 show a state in which the fiber bundle F2 of the second round trip is in contact with the end face of the fiber bundle F1 of the first round trip, for easy understanding. Similarly, the fiber bundles F3, . As a result, the gaps between the fiber bundles F1 in the first round trip are sequentially filled from one side to the other by the fiber bundles F2, F3, . A method for arranging the fiber bundles F in this manner will be described in detail below.

Specifically, the number of times the liner 11 is reciprocated along the central axis L when forming one helical layer is M (where M is an integer equal to or greater than 2), and the rotation angle per reciprocation of the liner 11 is α °, the number of guide members 40 is n (where n is an integer of 2 or more, here 9), the number of reciprocations M of the liner 11, the rotation angle α per one reciprocation of the liner 11, the number of guide members 40 n and k (where k is an integer) satisfy the following formula (1).
α=360/(n×M)+(360/n)×k (1)

The number of reciprocations M of the liner 11 when forming one helical layer depends on the width of the fiber bundle F along the circumferential direction of the liner 11, variations in the width of the fiber bundle F, the circumferential length of the liner 11, and the guide member. It can be easily set using the number n of 40. For example, if W is the width of the fiber bundle F along the circumferential direction of the liner 11, e is the variation in the width of the fiber bundle F, and C is the circumferential length of the liner 11, then the length of the liner 11 when forming one helical layer is The number of round trips M is set so as to satisfy C≦(We)×n×M. Since the amount of overlap between adjacent fiber bundles F increases as the number of reciprocations M increases, the smaller the number of reciprocations M, the better.

Next, the above formula (1) will be explained. Since n×M is the total number of fiber bundles F passing through the tubular portion 11a in a predetermined direction when one helical layer is formed so as to cover the circumference of the tubular portion 11a without gaps in the circumferential direction, 360/(n ×M) is the pitch (angle) in the circumferential direction of the fiber bundles F forming one helical layer. Assuming that the rotation angle of the liner 11 per reciprocation is 360/(n×M), each time the liner 11 makes one reciprocation, the fiber bundle F is rotated by the same guide member 40 from the previous wound portion in the circumferential direction. is arranged in a portion shifted by one bundle (one pitch). In other words, the fiber bundles F are arranged continuously in the circumferential direction (that is, sequentially so as to contact one side end of the same fiber bundle F) without gaps with respect to the previously wound fiber bundle F. be.

360/n is the pitch (angle) of the plurality of guide members 40 in the circumferential direction. Therefore, if the liner 11 rotates (360/n)×k per reciprocation, the portion of the liner 11 that faces the guide members 40 (the portion where the fiber bundles F are arranged) is shifted from one of the guide members 40 , and the fiber bundle F is always wound around the same portion of the liner 11 .

In the method for manufacturing the high-pressure tank 10 of the present embodiment, as described above, the rotation angle α per reciprocation of the liner 11 is 360/(n×M)+(360/n)×k. Each time the is reciprocated once, the fiber bundle F is sequentially arranged so as to come into contact with one side end of the previously arranged fiber bundle F.

Therefore, when the liner 11 makes one reciprocation and then makes one reciprocation (second reciprocation), as shown in FIG. placed in contact with Then, when the liner 11 makes one round trip (the third round trip), as shown in FIG. placed. In this way, since the fiber bundle F is arranged in contact with one side end of the previously arranged fiber bundle F, the gap between the fiber bundles F1 in the first round trip is the same as the one side of the fiber bundle F1. It is filled in order from the end side. The fiber bundle F for the Mth round trip is arranged so that no gap is formed between the fiber bundle F for the M−1 round trip and the fiber bundle F1 for the first round trip.

In this way, between the fiber bundles F1 in the first round trip, on one side (one side end side), the fiber bundles F are arranged in contact with each other, so a gap is formed between the fiber bundles F. is suppressed. As a result, it is possible to prevent the fiber bundles F3, .

In addition, between the fiber bundles F1 of the first round trip, the gap between the fiber bundles F becomes larger on the other side. As a result, for example, the fiber bundles F3, .

In this way, between the fiber bundles F1 of the first round trip, both the one side portion and the other side portion are in a state where the fiber bundle F is bridged with the fiber bundle F arranged before. can be suppressed, it is possible to suppress the formation of voids in the fiber reinforced resin layer.

Next, an experiment conducted to confirm the effects of the method for manufacturing the high-pressure tank 10 of this embodiment will be described. In this confirmatory experiment, an example corresponding to this embodiment and a comparative example will be described.

(Example)
In the example, the number of reciprocations M of the liner 11 was 10, the number n of the guide members 40 was 9, and k was 5. Also, using the above formula (1), the rotation angle α° per reciprocation of the liner 11 was set to 204°. Then, the fiber bundle F was wound around the liner 11 by a plurality of (here, nine) guide members 40 to form one helical layer. At this time, as in FIGS. 4 and 5, the gaps between the fiber bundles F1 in the first round trip were filled from one side to the other by the fiber bundles F2, F3, . . . in the second and subsequent round trips. FIG. 6 shows the relationship between the number of reciprocations of the liner 11 and the relative angle around the central axis L between the predetermined position of the liner 11 and each guide member 40 at this time. As shown in FIG. 6, for example, the guide member 40e arranges the fiber bundle F2 so as to contact the fiber bundle F1 arranged by the guide member 40a in the first reciprocation, and the fiber bundle F2 in the second reciprocation. Following this, the fiber bundle F3 arranged by the guide member 40i in the third reciprocation and the fiber bundle F4 arranged by the guide member 40d in the fourth reciprocation were arranged so as to come into contact with each other in this order.

After ten helical layers were formed in the same manner as the first layer, the high-pressure tank 10 was heated to cure the fiber-reinforced resin layer 12 .

(Comparative example)
In the comparative example, the number of reciprocations M of the liner 11 was set to 10, and the number n of the guide members 40 was set to nine. On the other hand, the rotation angle per reciprocation of the liner 11 was set without using the above formula (1). Then, the fiber bundle F was wound around the liner 11 by a plurality of (here, nine) guide members 40 to form one helical layer. At this time, as in FIG. 10, the fiber bundle F2 of the second round trip was arranged at a predetermined interval from the fiber bundle F1 of the first round trip, and gaps were formed on both sides in the width direction of the fiber bundle F2 of the second round trip. . Similarly, the fiber bundle F3 of the third round trip is arranged at a predetermined interval with respect to the fiber bundle F1 of the first round trip and the fiber bundle F2 of the second round trip. A gap was formed in Similarly, the fiber bundles F4, .

After ten helical layers were formed in the same manner as the first layer, the high-pressure tank 10 was heated to cure the fiber-reinforced resin layer 12 .

Then, the high-pressure tanks 10 according to the example and the comparative example were cut at positions A to J shown in FIG. 7, and the void fractions of the fiber reinforced resin layer 12 were measured at eight points on each cut surface. The void ratio was measured by photographing the measurement location by X-ray CT, binarizing the photographed image to determine the presence or absence of voids, and calculating the area ratio of voids. The results are shown in FIGS. 8 and 9, respectively. 8 and 9 show eight void fractions at each position and an average value (bar graph) of void fractions at each position.

As shown in FIG. 8, in the example, the average void fractions at positions B to I of the cylindrical portion 11a are respectively 0.5%, 0.9%, 0.6%, 0.3%, 0.5%, 0.2%, 0.1% and 0.2%, and the void fractions at positions A and J of the dome portion 11b were 5.9% and 6.1%, respectively. . Further, the average of all void fractions in the cylindrical portion 11a of the example was 0.4%, and the average of all void fractions in the dome portion 11b was 6.0%.

On the other hand, as shown in FIG. 9, in the comparative example, the average void fractions at positions B to I of the cylindrical portion 11a are 1.3%, 1.4%, 2.8%, and 2.1%, respectively. %, 3.6%, 3.8%, 2.3% and 1.2%, and the void fractions at positions A and J of the dome portion 11b are 6.9% and 7.9%, respectively. there were. In addition, the average total void fraction in the cylindrical portion 11a of the comparative example was 2.3%, and the average total void fraction in the dome portion 11b was 7.4%.

Therefore, in the example, the void ratio in the tubular portion 11a was reduced by 1.9%, and the void ratio in the dome portion 11b was reduced by 1.4%, as compared with the comparative example. It is considered that the reason why the void fraction of the example is lower than that of the comparative example is as follows. That is, in the embodiment, the gap between the fiber bundles F1 in the first round trip is sequentially filled from one side to the other by the fiber bundle F2 in the second round trip and thereafter. . . can be suppressed from being bridged with the fiber bundle F arranged before it. For this reason, it is considered that the occurrence of voids in the fiber reinforced resin layer 12 after curing could be suppressed.

It should be noted that the embodiments disclosed this time should be considered as examples and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the description of the above-described embodiments, and includes all modifications within the meaning and scope equivalent to the scope of the claims.

For example, in the above-described embodiment, an example in which the circumference of the liner 11 is used when setting the number of reciprocations M of the liner 11 for forming one helical layer has been described, but the present invention is not limited to this. As the fiber bundles F are arranged on the outer surface of the liner 11, the circumferential length around the liner 11 and the fiber bundles F increases. The number of reciprocations M of the liner 11 may be set using the circumference. That is, the number of reciprocations M may be reset each time one helical layer is formed.

10: high pressure tank, 11: liner, 11a: cylindrical portion, 11b: dome portion, 40, 40a to 40i: guide member, F, F1 to F3: fiber bundle, L: central axis

Claims (1)

For a liner having a cylindrical tubular portion and dome portions provided at both ends of the tubular portion, a plurality of guide members arranged around the liner at equal intervals centering on the central axis of the liner to guide fiber bundles. is supplied to form one or more helical layers made of fiber-reinforced resin so as to cover the cylindrical portion and the pair of dome portions, wherein
The liner is reciprocated M times (where M is an integer of 2 or more) along the central axis in forming one helical layer so as to cover the periphery of the cylindrical portion in the circumferential direction without gaps, and the liner is is rotated by α° per reciprocation, and the fiber bundle is supplied from n guide members (where n is an integer of 2 or more) to form the helical layer on the liner,
The number of reciprocations M of the liner, the rotation angle α per one reciprocation of the liner, the number n of the guide members, and k (where k is an integer) satisfy the following formula (1): How the tank is made.
α=360/(n×M)+(360/n)×k (1)

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