Method for manufacturing bushing for pressure vessel, and bushing for pressure vessel

Abstract

This bushing for a pressure vessel is provided with: a main body part having a central part and a tapered part; and a plurality of connection parts which connect two adjacent main body parts in series via the tapered parts, have a smaller diameter than the central part, and are bent to fold the main body parts. The manufacturing method is provided with: a step in which a cylindrical molding support member having an outer diameter corresponding to the inner diameter of the connection part is disposed on the inner side of a site corresponding to the connection part of the preliminary molded body while extruding the preliminary molded body having a cylindrical shape having a predetermined inner diameter; the bush is manufactured by hollow molding in a state in which the bush is in contact with the inner side of the connecting part.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a method for manufacturing a bushing for a pressure vessel and the bushing itself. Background Technology

[0002] Conventionally, pressure vessels for storing fluids are known to have a structure in which a cylindrical main body and a connecting part, also cylindrical but with a smaller diameter than the main body, are alternately arranged as a bushing (Japanese Patent Table 2018-519480, Figure 5c, etc.). Such bushings are sometimes manufactured, for example, by continuously hollowing an extruded cylindrical body using a pair of rotating die sets to form the main body and the small-diameter connecting part, thus producing the bushing before bending. This method is advantageous in that it allows for the continuous forming of the main body and connecting part of the bushing in one step. Then, the bushing is bent to bend the connecting part and fold the main body, thereby obtaining a folded pressure vessel. Summary of the Invention

[0003] However, in this bushing, since a cylindrical body with a constant wall thickness is continuously formed into a large-diameter main body and a small-diameter connecting part, the wall thickness of the small-diameter connecting part tends to increase compared to the main body. Furthermore, the wall thickness of the connecting part may be uneven.

[0004] In this situation, when bending the bushing, it is difficult to apply a uniform load due to the increased and uneven wall thickness at the connection, making bending difficult. Therefore, bending efficiency decreases, and it is difficult to achieve a uniform shape at the connection.

[0005] This specification provides a technique for bushings of pressure vessels that are continuously formed and easily bent.

[0006] This specification specifically describes a method for manufacturing a bushing for a pressure vessel. The bushing includes: a main body portion having a central portion and a tapered portion; and a plurality of connecting portions connecting adjacent main bodies portion in series via the tapered portions, the tapered portions having a diameter smaller than the central portion and being bent to fold the main body portion. The manufacturing method includes the following steps: while extruding a cylindrical preform having a predetermined inner diameter, a cylindrical forming auxiliary member having an outer diameter corresponding to the inner diameter of the connecting portion is disposed on the inner side of the preform, and hollowly formed while abutting against the inner side of the connecting portion, thereby manufacturing the bushing.

[0007] According to the manufacturing method of this bushing, by abutting the forming auxiliary member against the inner side of the portion corresponding to the connecting part, the connecting part is formed with a desired and uniform wall thickness, thus obtaining a connecting part with the desired wall thickness, inner diameter, and shape. As a result, bending processing at the connecting part of the bushing can be easily performed.

[0008] In another embodiment of this manufacturing method, the process may include the use of a set of molds comprising multiple pairs of molds configured to face the pre-formed body on predetermined tracks. This enables the efficient manufacture of bushings.

[0009] In another embodiment of this manufacturing method, the process may include forming the bushing by adding a groove to the inner outer surface of the connecting portion when it is bent. This allows for the manufacture of a bushing with a connecting portion that is easier to bend.

[0010] In another aspect of this manufacturing method, there may also be a step of bending the connecting portion of the bushing and folding the main body portion.

[0011] This specification is also specifically applied to the bushing of a pressure vessel. The bushing includes: a main body portion having a central portion and a tapered portion; and a plurality of connecting portions connecting two adjacent main bodies in series via the tapered portions, the tapered portions having a smaller diameter than the central portion and being bent to fold the main bodies. The connecting portions have thick-walled portions between the connecting portions and at least one of the adjacent tapered portions.

[0012] According to this bushing, by having a thick-walled portion at the end of the tapered side of the connection, the increase in wall thickness at the connection can be suppressed, and the bending process at the connection can be facilitated. Attached Figure Description

[0013] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals denote like elements, wherein:

[0014] Figure 1 This is a diagram showing a summary of the manufacturing process of the bushing of a pressure vessel.

[0015] Figure 2 This is a diagram showing an example of a forming device.

[0016] Figure 3 This is a diagram showing the state of the bushing connection during its forming process.

[0017] Figure 4 This diagram shows the state during the forming of the groove shape for the connecting part. Detailed Implementation

[0018] The following description, with reference to appropriate accompanying drawings, explains the manufacturing method of the pressure vessel bushing disclosed in this specification. In this specification, the fluid stored in the pressure vessel is not particularly limited; for example, it may be hydrogen, natural gas, helium, dimethyl ether, liquefied petroleum gas, xenon, etc.

[0019] Pressure vessels are typically formed by folding a braid of fiber-reinforced plastic material, such as CFRP, into a prescribed shape on the surface of the bushing 110. For example, the braid may be integrally formed on the surface of the bushing 110 before or during bending of the bushing 100, or integrally formed on the surface of the processed bushing 110 after bending of the bushing 100. For ease of explanation, a description of the braid will be omitted below.

[0020] Figure 1 The upper part represents a portion of the bushing 100 of the pressure vessel before bending, and the lower part represents the bushing 110 after bending. Figure 2 An example of forming apparatus 200, Figure 3 This indicates the cross-section of the connecting part 20 during its forming process. Figure 4 This indicates the cross-section when a groove shape is added to the surface of the connecting part 20 and formed. Additionally, in Figures 2 to 4 In the figure, the pre-formed body 30 moves from left to right. First, the outline of the bushing 100 is explained, and then the manufacturing method of the bushing 100 is described.

[0021] like Figure 1 As shown in the upper part, the bushing 100 has a configuration in which multiple main body portions 10 and multiple connecting portions 20 are arranged alternately in series. The main body portion 10 has a central portion 12 and a tapered portion 14. The central portion 12 has a cylindrical shape extending with a predetermined diameter. The tapered portion 14 has a pointed shape whose diameter gradually decreases from the central portion 12 and is consistent with the diameter of the connecting portion 20.

[0022] The connecting portion 20 has a cylindrical shape with a diameter smaller than that of the central portion 12. The connecting portion 20 connects to adjacent main body portions 10 via a tapered portion 14. The connecting portion 20 is configured to be bent to fold the main body portion 10. By employing a configuration in which multiple main body portions 10 and multiple connecting portions 20 are alternately connected in series, a configuration can be obtained... Figure 1 The lower part shows the folded shape of the bushing 110.

[0023] The bushing 100 is formed by hollow forming (blow molding) of a cylindrical preform (preform) using a mold. The preform is obtained by extruding a resin material of a specified composition. The mold has forming surfaces corresponding to the main body 10 and the connecting part 20. Since the bushing 100 is to be folded, it is formed as an elongated body. Therefore, it is preferable to form it continuously in one piece by continuous blow molding.

[0024] Specifically, such as Figure 2 As shown, blow molding is preferably performed using a forming apparatus 200 equipped with a die assembly 40 on a predetermined track Z. According to the forming apparatus 200, the die assembly 40 is moved in conjunction with the extrusion of the pre-formed body 30, enabling the alternating and continuous forming of multiple main body portions 10 and multiple connecting portions 20 from the pre-formed body 30. The die assembly 40 is composed of pairs of dies 42, 44, and 46 arranged opposite to the extruded pre-formed body 30. The die assembly 40 can be formed into a unit structure including at least one main body portion 10 and at least one connecting portion 20. The forming apparatus 200 also includes an extrusion forming apparatus (not shown) that extrudes the pre-formed body 30 and extrudes it into the die assembly 40.

[0025] Furthermore, in this forming apparatus 200, a forming aid member 50 is arranged from near the extrusion port of the pre-formed body 30 to the inner side of the pre-formed body 30 along the extrusion direction of the pre-formed body 30. The forming aid member 50 has a length approximately equal to the range of the dies 42, 44, 46 of the die set 40. The forming aid member 50 is, for example, a metal tube.

[0026] like Figure 3 As shown, the forming auxiliary member 50 has multiple vent holes 52. By blowing pressurized gas into the inside of the pre-formed body 30 through the hollow part of the forming auxiliary member 50, pressurized gas can be evenly supplied into the pre-formed body 30.

[0027] The outer diameter of the forming auxiliary component 50 is set such that the desired wall thickness is added to the connecting portion 20 by means of the forming surfaces of the molds 42, 44, and 46 that constitute the mold group 40 and the outer surface of the forming auxiliary component 50.

[0028] The shape of the forming auxiliary member 50 is not particularly limited, for example, it is not particularly limited to a circle, an ellipse, a quadrilateral, etc. The shape of the connecting part 20 is defined by the shape of the forming auxiliary member 50.

[0029] To form the bushing 100, firstly, a resin material of a specified composition is melted and extruded to form a pre-formed body 30. Furthermore, the resin material of the bushing 100 is not particularly limited; examples include one or more resin materials selected from polyamide (PA), ethylene-vinyl alcohol copolymer (EVOH), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), and linear low-density polyethylene (LLDPE). The bushing 100 can be a multilayer structure using one or more layers of these resin materials. Additionally, considering bending processes, it may also include elastomer materials such as rubber.

[0030] like Figure 3As shown, the continuously extruded pre-formed body 30 enters the track Z on which the die set 40 is arranged opposite, and is gradually closed by the die 42 and the like. At the same time as the die closes, pressurized gas is blown into the interior of the pre-formed body 30 via the forming auxiliary member 50.

[0031] Since the forming aid member 50 is disposed inside the pre-formed body 30, at the forming portion of the connecting portion 20 of the pre-formed body 30, the forming aid member 50 closes the mold while abutting against the forming surface of the connecting portion 20 in the mold assembly 40, forming the connecting portion 20 in a stamping-forming manner. As a result, the connecting portion 20 can be formed to the desired thickness and shape. As the pre-formed body 30 moves along the extrusion direction, the forming portion of the connecting portion 20 of the pre-formed body 30 is abutted by the forming aid member 50 at least once and formed in a stamping-forming state. In addition, the connecting portion 20 is temporarily stamped-formed by the forming aid member 50 and the forming portion of the connecting portion 20 in the mold assembly 40, and then, as the pre-formed body 30 moves on the track Z, the forming portion of the connecting portion 20 separates from the forming aid member 50. During the period when it is not abutting against the forming aid member 50, the forming portion is formed by pressurized gas.

[0032] Furthermore, when the connecting portion 20 is formed by stamping using the forming surfaces of the forming aid 50 and the die assembly 40, excess resin material may move to the tapered portion 14. As a result, a thick-walled portion 24 may be formed between the connecting portion 20 and the adjacent tapered portion 14. The thick-walled portion 24 is formed at the end of the connecting portion 20 near the tapered portion 14, forming a thick wall throughout its entire inner circumference or a portion thereof. The thick-walled portion 24 ensures the wall thickness and shape of the connecting portion 20 as intended by the forming aid 50. The thick-walled portion 24 is sometimes formed, for example, between the connecting portion 20 and the tapered portion 14 located on the rear side of the connecting portion 20 in the extrusion direction. In addition, the thick-walled portion 24 may be formed between the connecting portion 20 and both adjacent tapered portions 14.

[0033] In addition, such as Figure 4 As shown, the forming surface of the forming connection portion 20 in the mold assembly 40 can have a convex forming portion 48, and this forming portion 48 can have a groove 22 added to the outer surface corresponding to the inner side when the connection portion 20 is bent. In this way, the bending process at the connection portion 20 can be performed more easily.

[0034] On the other hand, pressurized gas is supplied to the forming portion of the main body 10 of the pre-formed body 30 via the forming auxiliary member 50. As a result, the main body 10 defined by the forming surface of the mold assembly 40 is blow-formed.

[0035] When the pre-formed body 30 is formed by attaching the desired shape through the mold assembly 40, the mold assembly 40 opens and the bushing 100, which alternately has the main body 10 and the connecting part 20, is discharged onto the track Z.

[0036] The resulting bushing 100 has the desired thickness at the connecting portion 20, without becoming a thick wall or having uneven thickness. Furthermore, the connecting portion 20 also has the desired shape. As a result, when the bushing 100 is bent in a subsequent process to obtain the bushing 110, the bending process becomes simple, thus enabling a bending process without shape defects to be performed with excellent production efficiency.

[0037] Furthermore, in the above embodiments, the forming aid member 50 extends along the entire length of the die assembly 40, but is not limited thereto. The forming aid member 50 can be positioned within a range from near the extrusion port of the pre-formed body 30 to the forming portion of the initial connecting part 20. Even in this case, since the forming is temporarily stamped by the forming aid member 50, the desired wall thickness and shape are easily obtained, and the bending process at the connecting part 20 can be facilitated.

[0038] Furthermore, in the above embodiments, the forming apparatus 200 performs blow molding using pressurized gas, but it can also be formed using vacuum forming. Additionally, in the above embodiments, a groove 22 is added to the inner portion when the connecting portion 20 is bent, but this is not a limitation; a bent or folded shape can also be added to the outer portion of the connecting portion 20 to facilitate bending processing. In this case, both the mold assembly 40 and the forming auxiliary member 50 need to be fitted with a specified shape.

[0039] Furthermore, while the above embodiments have described bushing 100 and bushing 110 after bending, this specification also provides a pressure vessel having such bushings 100 and 110, and a method for manufacturing the pressure vessel. The structure and manufacturing method of the pressure vessel using bushings 100 and 110 for storing fluids such as hydrogen are well known to those skilled in the art.

[0040] This instruction manual includes the following structure.

[0041] [1] A method for manufacturing a bushing for a pressure vessel, wherein,

[0042] The bushing includes: a main body having a central portion and a tapered portion; and a plurality of connecting portions that connect two adjacent main bodies in series via the tapered portions, the tapered portions having a diameter smaller than the central portion and being bent to fold the main bodies.

[0043] The manufacturing method includes the following steps: while extruding a cylindrical preform with a specified inner diameter, a cylindrical forming auxiliary member with an outer diameter corresponding to the inner diameter of the connecting portion is disposed on the inner side of the preform corresponding to the connecting portion, and hollow forming is performed in a state of abutting against the inner side of the connecting portion to manufacture the bushing.

[0044] [2] According to the manufacturing method described in [1], wherein,

[0045] The process includes using a mold set comprising a plurality of pairs of molds configured to be opposite the pre-formed body on a predetermined track.

[0046] [3] According to the manufacturing method described in [1] or [2], wherein,

[0047] The process includes forming the connection by adding a groove shape to the outer surface located on the inside when the connection is bent.

[0048] [4] The manufacturing method according to any one of [1] to [3], wherein,

[0049] It also includes a process for bending the connecting portion of the bushing.

[0050] [5] A bushing for a pressure vessel, wherein,

[0051] The bushing includes: a main body having a central portion and a tapered portion; and a plurality of connecting portions that connect two adjacent main bodies in series via the tapered portions, the tapered portions having a diameter smaller than the central portion and being bent to fold the main bodies.

[0052] The connecting portion has a thick-walled portion between the connecting portion and at least one of the adjacent tapered portions.

[0053] The technical elements described in this specification or drawings, individually or in various combinations, contribute to technical utility and are not limited to the combinations recorded in the claims at the time of application. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically practical.

Claims

1. A method for manufacturing a bushing for a pressure vessel, wherein, The bushing includes: a main body having a central portion and a tapered portion; and a plurality of connecting portions that connect two adjacent main bodies in series via the tapered portions, the tapered portions having a diameter smaller than the central portion and being bent to fold the main bodies. The manufacturing method includes the following steps: while extruding a cylindrical preform with a specified inner diameter, a cylindrical forming auxiliary member with an outer diameter corresponding to the inner diameter of the connecting portion is disposed on the inner side of the preform corresponding to the connecting portion, and hollow forming is performed in a state of abutting against the inner side of the connecting portion to manufacture the bushing.

2. The manufacturing method according to claim 1, wherein, The process includes using a mold set comprising a plurality of pairs of molds configured to be opposite the pre-formed body on a predetermined track.

3. The manufacturing method according to claim 1, wherein, The process includes forming the connection by adding a groove shape to the outer surface of the inner side when bending the connection.

4. The manufacturing method according to any one of claims 1 to 3, wherein, It also includes a process for bending the connecting portion of the bushing.

5. A bushing for a pressure vessel, wherein, The bushing includes: a main body having a central portion and a tapered portion; and a plurality of connecting portions that connect two adjacent main bodies in series via the tapered portions, the tapered portions having a diameter smaller than the central portion and being bent to fold the main bodies. The connecting portion has a thick-walled portion between the connecting portion and at least one of the adjacent tapered portions.

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