Mold Structure for High-Pressure Tank

Abstract

To provide a mold structure for a high-pressure tank that can manufacture high-quality high-pressure tanks at low cost.SOLUTION: A mold structure 1 for a high-pressure tank is a structure for accommodating a preform 2 in which a fiber bundle is wound around an outer peripheral surface of a liner, and for impregnating the fiber bundle of the preform 2 with a resin. The mold structure 1 for the high-pressure tank includes: a main mold 10 that has an upper mold 11 and a lower mold 12 and accommodates the preform 2; and a main body 20 that has at least a resin injection part 23 that injects the resin into the main mold 10 and a product push-up part 24 that pushes up the preform 2 impregnated with the resin. The main mold 10 is detachably attached to the main body 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a mold structure for a high-pressure tank.

Background Art

[0002] As a high-pressure tank mounted on a fuel cell vehicle or the like, there is known one including a liner having a cylindrical body portion and a pair of dome portions provided at both axial ends of the body portion, and a fiber-reinforced resin layer covering the outer peripheral surface of the liner. A high-pressure tank having such a structure is manufactured by the FW (Filament Winding) method. In the FW method, first, a liner is formed, and using the formed liner as a winding core, a fiber bundle impregnated with resin is wound around the outer peripheral surface of the liner a plurality of times, or while impregnating the fiber bundle with resin, it is wound around the outer peripheral surface of the liner a plurality of times to manufacture a high-pressure tank.

[0003] Recently, a manufacturing method of a high-pressure tank using the RTM (Resin Transfer Molding) method has been developed. That is, after placing a preform (also referred to as an intermediate body) in which a fiber bundle is wound around the outer peripheral surface of a liner into a mold, a fluid uncured resin is injected into the mold, and the resin is impregnated into the fiber bundle of the preform and cured to manufacture a high-pressure tank. And as a mold used for the RTM method (hereinafter referred to as an "RTM molding mold"), for example, as described in Patent Document 1 below, there is one having a base mold and an insert mold housed in the central portion of the base mold.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Because of the relationship between the space mounted on the vehicle and the gas loading capacity of the high-pressure tank, the diameter, length, etc. are different, so preforms with various shapes are required. Also, in the case of an RTM molding die, the molding conditions for impregnating the resin well into the preform with the fiber bundle wound thick are severe, and there are many structures necessary to realize such molding conditions. Therefore, just by replacing only the nested mold that houses the preform, it is difficult to accurately fill and impregnate the resin, leading to a problem of deterioration in the quality of the manufactured high-pressure tank. In addition, in order to ensure the quality, it is conceivable to prepare an RTM molding die for each shape of the preform, but a new problem of an increase in manufacturing cost arises.

[0006] The present invention has been made to solve such technical problems, and an object thereof is to provide a mold structure for a high-pressure tank that can manufacture a high-quality high-pressure tank at low cost.

Means for Solving the Problems

[0007] The mold structure for a high-pressure tank according to the present invention is a mold structure for a high-pressure tank that houses a preform in which a fiber bundle is wound around the outer peripheral surface of a liner and impregnates the fiber bundle of the preform with resin, and has an upper mold and a lower mold, and at least includes a main mold that houses the preform, a resin injection part that injects resin into the main mold, and a product pushing-up part that pushes up the preform impregnated with resin. The main mold is detachably provided on the main body.

[0008] In the mold structure for a high-pressure tank according to the present invention, it includes a main mold for accommodating a preform, and a main body having at least a resin injection part and a product pushing-up part. Since the main mold for accommodating the preform is detachably provided on the main body, by only replacing the main mold corresponding to preforms of different shapes, different-shaped high-pressure tanks can be manufactured with good quality while maintaining the functions of resin injection and resin impregnation necessary for molding. Also, compared with the case of preparing a molding die for each shape of the preform, since the main body having at least a resin injection part and a product pushing-up part can be reused, low cost can be realized. As a result, high-quality high-pressure tanks can be manufactured at low cost.

[0009] In the mold structure for a high-pressure tank according to the present invention, the upper mold has a pipe for vacuum degassing built therein. The main body has an upper main body and a lower main body that are relatively movable. The upper mold and the lower mold are respectively attached to the upper main body and the lower main body so as to be mold-clampable. The mold structure for a high-pressure tank is provided so as to surround the preform accommodated in the main mold, and preferably further includes an annular sealing member that seals between the upper main body and the lower main body, and between the upper mold and the lower mold. In this way, the sealing performance of the mold structure can be ensured without being affected by the replacement of the main mold, so that molding defects such as voids can be prevented.

[0010] In the mold structure for a high-pressure tank according to the present invention, the resin injection part preferably has a resin injection pipe provided on the upper main body, a resin storage part provided on the lower main body and storing the resin from the resin injection pipe, and a resin extrusion part provided on the lower main body and extruding the resin stored in the resin storage part to the main mold side. In this way, the resin injection into the main mold can be accurately performed without being affected by the replacement of the main mold. Also, by once storing the resin in the resin storage part and then extruding it to the main mold side instead of directly injecting the resin into the main mold, the fiber displacement of the fiber bundle due to high-pressure resin injection can be prevented.

[0011] Also, in the mold structure for a high-pressure tank according to the present invention, it is preferable that the resin extrusion part has a movable pin provided at the bottom of the resin reservoir part to adjust the depth of the resin reservoir part. By doing so, by adjusting the depth of the resin reservoir part with the movable pin, the pressure of the resin injected into the main mold can be controlled, and fiber displacement of the fiber bundle due to high-pressure resin injection can be prevented.

[0012] Also, in the mold structure for a high-pressure tank according to the present invention, it is preferable that the product lifting part has a lifting member that penetrates the lower mold and lifts the preform accommodated in the main mold. By doing so, even when the main mold is replaced, the preform impregnated with resin can be taken out accurately.

[0013] Furthermore, in the mold structure for a high-pressure tank according to the present invention, it is preferable that temperature control pipes extending along the longitudinal direction of the preform are respectively built in the upper mold and the lower mold. By doing so, the temperature of the main mold can be stabilized, so that the quality of the manufactured high-pressure tank can be improved.

Effects of the Invention

[0014] According to the present invention, a high-quality high-pressure tank can be manufactured at low cost.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0016] Hereinafter, an embodiment of a mold structure for a high-pressure tank according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view showing the mold structure for a high-pressure tank according to the embodiment, FIG. 2 is a schematic transverse sectional view showing the mold structure for a high-pressure tank according to the embodiment, and FIG. 3 is a plan view showing the lower mold and the lower body.

[0017] The mold structure 1 for a high-pressure tank of the present embodiment is a structure related to a mold for RTM molding, which accommodates a preform 2 that is an intermediate body of the high-pressure tank, impregnates the fiber bundles of the preform 2 with resin, and further cures the impregnated resin to manufacture the high-pressure tank. The preform 2 is, that is, a high-pressure tank before resin impregnation, and is formed by a substantially cylindrical liner having a storage space for storing high-pressure gas and a fiber bundle wound around the outer peripheral surface of the liner. The liner has a cylindrical body portion and a pair of dome portions provided at both axial ends of the body portion.

[0018] The fiber bundle is formed, for example, by winding fibers around the outer peripheral surface of the liner multiple times by the FW method. Examples of the fibers here include carbon fibers, glass fibers, aramid fibers, and the like. Examples of the resin impregnated in the fiber bundle include thermosetting resins such as epoxy resins, unsaturated polyester resins, and polyamide resins, but thermoplastic resins such as polyethylene resins and polyester resins can also be used.

[0019] The mold structure 1 for a high-pressure tank of the present embodiment includes a main mold 10 that accommodates the preform 2 and a main body 20 that has at least a resin injection portion 23 and a product pushing-up portion 24. The main mold 10 is detachably provided on the main body 20.

[0020] The main mold 10 has an upper mold 11 and a lower mold 12. The upper mold 11 is detachably attached to the upper body 21 described later, and the lower mold 12 is detachably attached to the lower body 22 described later. Since the upper body 21 and the lower body 22 are provided so as to be relatively movable in the vertical direction, the upper mold 11 and the lower mold 12 can be clamped. And when the upper mold 11 and the lower mold 12 are clamped, a space (also referred to as a cavity) for accommodating the preform 2 is formed inside the main mold 10. This space is made larger by, for example, the tolerance of the preform 2.

[0021] Temperature control pipes for adjusting the temperatures of the upper mold 11 and the lower mold 12 are respectively built into the upper mold 11 and the lower mold 12. Specifically, inside the upper mold 11, a plurality of temperature control pipes 13 extending along the longitudinal direction of the preform 2 (that is, the axial direction of the preform 2) accommodated in the main mold 10 are arranged. In the present embodiment, there are two temperature control pipes 13, which are arranged symmetrically with respect to the axial center of the preform 2. A heater (not shown) is inserted into the temperature control pipe 13, and the upper mold 11 is heated by the heat of the heater. Note that the number of the temperature control pipes 13 is not limited to this, and may be appropriately increased or decreased in consideration of the size of the upper mold 11, the heating efficiency, and the like.

[0022] Also, inside the lower mold 12, a plurality of temperature control pipes 14 extending along the longitudinal direction of the preform 2 accommodated in the main mold 10 are arranged. In the present embodiment, there are two temperature control pipes 14, which are arranged symmetrically with respect to the axial center of the preform 2. A heater (not shown) is inserted into the temperature control pipe 14, and the lower mold 12 is heated by the heat of the heater. Note that the number of the temperature control pipes 14 is not limited to this, and may be appropriately increased or decreased in consideration of the size of the lower mold 12, the heating efficiency, and the like.

[0023] In addition, the upper mold 11 incorporates a vacuum degassing pipe 15 that extends along the longitudinal direction of the preform 2 accommodated in the main mold 10. One end of the vacuum degassing pipe 15 communicates with the space for accommodating the preform 2, and the other end is connected to a vacuum pump (not shown) disposed outside the mold structure 1 for the high-pressure tank. When the vacuum pump is driven, the inside of the main mold 10 (i.e., the space for accommodating the preform 2) can be vacuum degassed through the vacuum degassing pipe 15.

[0024] In addition to the resin injection part 23 and the product pushing-up part 24 described above, the main body 20 further includes an upper main body 21 and a lower main body 22 that are relatively movable in the vertical direction. In this embodiment, for example, the lower main body 22 is a fixed mold, and the upper main body 21 is a movable mold (a mold that moves relative to the fixed mold), but the upper main body 21 may be a fixed mold, the lower main body 22 may be a movable mold, or both the upper main body 21 and the lower main body 22 may be movable molds.

[0025] As shown in FIG. 1, the upper main body 21 is a frame body formed in a U-shaped cross section so as to have a space for attaching the upper mold 11 of the main mold 10. The lower main body 22 is a frame body formed in a U-shaped cross section so as to have a space for attaching the lower mold 12 of the main mold 10. The upper main body 21 and the lower main body 22 are each formed of a metal material and are arranged vertically with the U-shaped openings facing each other.

[0026] In addition, the mold structure 1 for the high-pressure tank includes a shaft 25 that pivotally supports the preform 2. The shaft 25 is formed so that it can be inserted into the caps arranged at both the left and right ends of the preform 2, and rotatably supports the preform 2. Further, this shaft 25 has a hollow structure and a plurality of through holes are provided in the peripheral wall of the portion inserted into the preform 2. In this way, the shaft 25 can also be used as an internal pressure supply member. That is, in order to prevent deformation and breakage of the preform 2 due to high-pressure resin injection, it is necessary to inject gas into the liner of the preform 2 to maintain the internal pressure of the preform 2. By using the shaft 25 having the above-described structure, pressure can be easily supplied to the inside of the liner. Note that the shaft 25 is connected to the internal pressure supply pipe 28. Further, the pressure supply to the liner is not limited to being performed via the shaft 25, and may be performed via, for example, the main mold 10.

[0027] The resin injection part 23 includes a resin injection pipe 231 provided in the upper main body 21, a plurality of resin storage parts 232 provided in the lower mold 12 and storing the resin from the resin injection pipe 231, and a resin extrusion part 233 provided in the lower mold 12 and extruding the resin stored in each resin storage part 232 toward the main mold 10 side.

[0028] The resin injection pipe 231 is fixed to the upper main body 21 in a state of extending from the upper main body 21 toward the lower main body 22. This resin injection part 23 is connected to a resin storage tank via a pipe and an on-off valve (not shown). In the resin storage tank, for example, a two-component thermosetting resin (for example, an epoxy resin) composed of a main agent and a curing agent is stored in a separated state.

[0029] As shown in FIG. 3, in this embodiment, the number of resin storage parts 232 is 16. These resin storage parts 232 are arranged eight by eight on both sides of the axis of the preform 2 accommodated in the main mold 10. On each side, the eight resin storage parts 232 are arranged at substantially equal intervals along the longitudinal direction of the preform 2. And each resin storage part 232 communicates with each other and also communicates with the resin injection pipe 231 respectively.

[0030] As shown in FIG. 1, each resin reservoir 232 is a columnar concave portion having a predetermined depth, and a resin extrusion portion 233 is provided at the bottom thereof. The resin extrusion portions 233 are provided one-to-one with respect to the resin reservoirs 232, and include a columnar piston portion 233a disposed at the bottom of the resin reservoir 232, and a movable pin 233b connected to the piston portion 233a and moving the piston portion 233a up and down as the servo motor rotates. When the movable pin 233b rises as the servo motor rotates, the piston portion 233a also rises, and the depth of the resin reservoir 232 becomes relatively shallow. As a result, the resin stored in the resin reservoir 232 is extruded out. On the other hand, when the movable pin 233b descends as the servo motor rotates, the piston portion 233a also descends, and the depth of the resin reservoir 232 becomes relatively deep. By using the movable pin 233b in this way, the depth of the resin reservoir 232 can be adjusted.

[0031] In addition, each resin reservoir 232 communicates with the inside of the main mold 10 via a runner 27. As shown in FIG. 3, the runners 27 are provided one-to-one with respect to the resin reservoirs 232 and are formed in the lower body 22 and the lower mold 12. The runner 27 is a groove extending along a direction orthogonal to the longitudinal direction of the preform 2 (i.e., the radial direction of the preform 2), one end of which communicates with the inside of the main mold 10, and the other end of which communicates with the resin reservoir 232. The runner 27 crosses the lower body 22 and the lower mold 12 so as to have a portion formed in the lower body 22 and a portion formed in the lower mold 12.

[0032] Here, the reason for providing the resin reservoir 232 will be explained. That is, when the high-pressure resin is injected into the main mold 10, the high-pressure resin may collide with the fiber bundles of the preform 2 and cause fiber displacement. In order to prevent fiber displacement due to high-pressure resin injection, in the mold structure 1 for a high-pressure tank of the present embodiment, instead of directly injecting the high-pressure resin into the inside of the main mold 10, the high-pressure resin is temporarily stored in the resin reservoir 232, and the resin stored in the resin reservoir 232 is gradually extruded toward the main mold 10 side by the movable pin 233b provided at the bottom of the resin reservoir 232, thereby adopting a method of controlling the pressure of the injected resin.

[0033] The product pushing-up part 24 is provided for pushing out the preform 2 impregnated with resin. It has two pushing-up members 241 that penetrate the lower main body 22 and the lower mold 12 and push up the preform 2 accommodated in the main mold 10, and a lever part 242 that connects the lower ends of the two pushing-up members 241. The two pushing-up members 241 each have an elongated shape extending along the longitudinal direction of the preform 2 and are arranged symmetrically with respect to the axis of the preform 2. And the upper surface of the pushing-up member 241 facing the preform 2 is a curved surface following the shape of the outer peripheral surface of the preform 2. Note that the pushing-up member 241 is formed so that it can be entirely lowered and accommodated in the lower main body 22 so as not to prevent the replacement of the lower mold 12.

[0034] When pushing out the preform 2 impregnated with resin using the product pushing-up part 24 having such a structure, for example, in the mold-open state, by holding the lever part 242 and pushing up the pushing-up member 241, the preform 2 is pushed up to a predetermined height.

[0035] Also, the mold structure 1 for the high-pressure tank includes an annular sealing member 26 that seals between the upper main body 21 and the lower main body 22, and between the upper mold 11 and the lower mold 12. As shown in FIG. 3, the sealing member 26 is, for example, an O-ring and is fitted into a circumferential groove (not shown) provided in the lower main body 22 and the lower mold 12 so as to surround the preform 2 accommodated in the main mold 10 and the resin reservoir part 232.

[0036] More specifically, the sealing member 26 has a pair of first parts 261 arranged outside the resin reservoir part 232 and extending along the longitudinal direction of the preform 2, and a pair of second parts 262 extending in the radial direction of the preform 2 so as to cross the lower main body 22 and the lower mold 12. In this embodiment, the sealing member 26 is a single O-ring, but it is not limited to this. For example, a double structure using two O-rings with different lengths may also be used.

[0037] The manufacturing method of the high-pressure tank using the mold structure 1 for the high-pressure tank will be briefly described below. The manufacturing method of the high-pressure tank mainly includes a first step of arranging a preform 2 inside a main mold 10 and clamping the mold, a second step of injecting resin into the main mold 10 after vacuum degassing, and a third step of curing the resin and taking out the high-pressure tank.

[0038] In the first step, first, the main mold 10 corresponding to the preform 2 to be impregnated with resin is attached to the main body 20. For example, the main molds 10 corresponding to preforms of different shapes are prepared in advance, and the one corresponding to the shape of the preform 2 to be impregnated with resin is taken out from them, and the upper mold 11 is attached to the upper main body 21 and the lower mold 12 is attached to the lower main body 22 and fixed respectively.

[0039] Subsequently, the prefabricated preform 2 is placed inside the main mold 10. Specifically, with the upper mold 11 attached to the upper main body 21 open, the preform 2 pivotally supported by the shaft 25 is placed in the lower mold 12. Subsequently, heaters are inserted into the temperature control pipes 13 built into the upper mold 11 and the temperature control pipes 14 built into the lower mold 12 respectively, and the mold is clamped while heating the upper mold 11 and the lower mold 12 respectively. After clamping, the inside of the main mold 10 is vacuum degassed using the vacuum degassing pipe 15 built into the upper mold 11 and a vacuum pump (not shown).

[0040] In the second step, after the vacuum degassing is completed, while supplying pressure into the liner of the preform 2, resin is injected into each resin reservoir 232. Specifically, gas is supplied into the liner using the internal pressure supply pipe 28 and the shaft 25. Subsequently, with the piston portion 233a of the resin extrusion portion 233 positioned at the bottom of the resin reservoir 232, the on-off valve is opened, and the two-component thermosetting resin stored in the resin storage tank is injected into each resin reservoir 232 through the resin injection pipe 231.

[0041] Subsequently, while observing the pressure situation inside the liner, the movable pin 233b is raised to raise the piston portion 233a, and the resin stored in the resin reservoir portion 232 is extruded toward the main mold 10 side. Then, the resin flows into the inside of the main mold 10 via the runner 27 that communicates with the resin reservoir portion 232. As a result, the impregnation of the resin into the fiber bundle of the preform 2 starts. At this time, based on the pressure inside the liner, the rising height of the movable pin 233b is adjusted to control the pressure of the resin flowing (in other words, injected) into the inside of the main mold 10.

[0042] After the resin impregnation is completed, the resin injection is stopped, and the resin is cured inside the main mold 10. Then, when the resin curing is completed, the upper body 21 is raised to open the mold, and then, using the product pushing-up portion 24, the preform 2 that has been impregnated with resin and cured is pushed up and taken out from the main mold 10. As a result, a high-pressure tank is manufactured.

[0043] In the mold structure 1 for a high-pressure tank of the present embodiment, it includes a main mold 10 that houses the preform 2, and a main body 20 having at least a resin injection portion 23 and a product pushing-up portion 24. Since the main mold 10 is detachably provided on the main body 20, by only replacing (in other words, exchanging) the main mold 10 corresponding to the preform 2 of a different shape, different-shaped high-pressure tanks can be manufactured with good quality while maintaining the functions of resin injection and resin impregnation necessary for molding, and the performance of the manufactured high-pressure tank can be improved.

[0044] Also, since it is possible to cope with the manufacture of high-pressure tanks of different shapes by only replacing the main mold 10 in this way, continuous production can be realized and productivity can be improved. Furthermore, compared with the case of preparing a molding die for each shape of the preform 2, since the main body 20 having at least the resin injection portion 23 and the product pushing-up portion 24 can be reused, low cost can be realized. As a result, high-quality high-pressure tanks can be manufactured at low cost.

[0045] In addition, an annular sealing member 26 is provided so as to surround the resin reservoir portion 232 and the preform 2 housed in the main mold 10, and seals between the upper main body 21 and the lower main body 22, and between the upper mold 11 and the lower mold 12. Thus, the sealing performance of the mold structure 1 for the high-pressure tank can be ensured without being affected by the replacement of the main mold 10, and molding defects such as voids can be prevented.

[0046] Furthermore, the resin injection portion 23 includes a resin injection pipe 231 provided in the upper main body 21, a resin reservoir portion 232 provided in the lower main body 22 and storing the resin from the resin injection pipe 231, and a resin extrusion portion 233 provided at the bottom of the resin reservoir portion 232 and having a movable pin 233b for adjusting the depth of the resin reservoir portion 232. Therefore, resin can be accurately injected into the main mold 10 without being affected by the replacement of the main mold 10, and fiber displacement of the fiber bundle due to high-pressure resin injection can be prevented.

[0047] Also, the product pushing-up portion 24 has a pushing-up member 241 that penetrates the lower mold 12 and pushes up the preform 2 housed in the main mold 10. Therefore, even when the main mold 10 is replaced, the preform 2 impregnated with resin can be accurately taken out. Furthermore, temperature control pipes 13 and 14 extending along the longitudinal direction of the preform 2 are respectively built in the upper mold 11 and the lower mold 12 of the main mold 10, so that the temperature of the main mold 10 can be stabilized. Accordingly, the quality of the manufactured high-pressure tank can be improved.

[0048] As described above in detail for the embodiments of the present invention, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims.

Explanation of Reference Numerals

[0049] 1: Mold structure for high-pressure tank, 2: Preform, 10: Main mold, 11: Upper mold, 12: Lower mold, 13, 14: Temperature control pipes, 15: Vacuum degassing pipe, 20: Body, 21: Upper body, 22: Lower body, 23: Resin injection part, 24: Product pushing-up part, 25: Shaft, 26: Seal member, 27: Runner, 28: Internal pressure supply pipe, 231: Resin injection pipe, 232: Resin storage part, 233: Resin extrusion part, 233a: Piston part, 233b: Movable pin, 241: Pushing-up member, 242: Lever part, 261: First part, 262: Second part

Claims

1. A mold structure for a high-pressure tank that houses a preform with a fiber bundle wound around the outer peripheral surface of a liner and impregnates the fiber bundle of the preform with resin, comprising an upper mold and a lower mold, a main mold for housing the preform, a body having at least a resin injection part for injecting resin into the main mold, and a product pushing-up part for pushing up the preform impregnated with resin, and the main mold is detachably provided on the body. The mold structure for a high-pressure tank is characterized by this.

2. The upper mold has a built-in pipe for vacuum degassing, the body has an upper body and a lower body that are relatively movable, the upper mold and the lower mold are respectively attached to the upper body and the lower body so that they can be clamped, The mold structure for a high-pressure tank is provided so as to surround the preform housed in the main mold, and further includes an annular sealing member that seals between the upper body and the lower body, and between the upper mold and the lower mold. The mold structure for a high-pressure tank according to Claim 1.

3. The resin injection part has a resin injection pipe provided on the upper body, a resin storage part provided on the lower body and storing the resin from the resin injection pipe, and a resin extrusion part provided on the lower body and extruding the resin stored in the resin storage part toward the main mold side. The mold structure for a high-pressure tank according to Claim 2.

4. The resin extrusion part has a movable pin provided at the bottom of the resin storage part for adjusting the depth of the resin storage part. The mold structure for a high-pressure tank according to Claim 3.

5. The product pushing-up part has a pushing-up member that penetrates the lower mold and pushes up the preform housed in the main mold. The mold structure for a high-pressure tank according to Claim 1.

6. The upper mold and the lower mold each have a temperature control pipe extending along the longitudinal direction of the preform. The mold structure for a high-pressure tank according to any one of Claims 1 to 5.

Images