Pressure vessel manufacturing method

Abstract

Provided is a pressure vessel (1) comprising a liner (2) and an insert member (3) that are integrally formed by blow molding the liner (2). The insert member (3) has a cylindrical shape with an inner-diameter opening (27). The liner (2) is molded integrally with the insert member (3) by inserting a parison through the inner-diameter opening (27) and performing blow molding. Since the liner (2) is inserted inside the insert member (3) and is blow molded, it is possible to prevent occurrence of a pinched portion. Consequently, it is possible to improve the strength, and to prevent a fluid from leaking from between the liner (2) and the insert member (3).

Description

[Technical Field]

[0001] The present invention , pressure This invention relates to a method for manufacturing a pressure vessel. [Background technology]

[0002] The background art of the present invention is the technology of Patent Document 1. This technology relates to a technique for manufacturing a liner of a pressure vessel for sealing a high-pressure fluid, etc., by blow molding. This resin liner is formed by inserting a mouthpiece inside a parison, which is a semi-fluid resin, and integrally molding the mouthpiece with the parison by blow molding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-119598 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the molding of the nozzle in Patent Document 1, the parison is clamped from the outside against the nozzle using a half-shaped mold, which causes pinched areas (areas of uneven thickness caused by pinching) to form in the liner surrounding the outer periphery of the nozzle. When pinched areas form, gaps tend to form between the nozzle and the liner, which may increase the risk of leakage of the enclosed fluid from the manufactured pressure vessel. Furthermore, when pinched areas form, stress concentrates in areas due to uneven thickness of the liner, which may reduce the strength of the pressure vessel.

[0005] Therefore, the present invention aims to improve the strength and to make it difficult for fluid to leak. High pressure The object is to provide a method for manufacturing a pressure vessel. [Means for solving the problem]

[0010] BookThe invention includes a first step of holding a cylindrical insert member having an inner diameter opening, and a second step of holding the inner diameter opening and the Bisei The method is characterized by comprising a second step of inserting the parison into the mold, and a third step of supplying air via a blow pin after the second step to transfer the parison to the molding surface and the inner diameter opening of the mold, thereby performing blow molding.

[0011] According to the present invention, the liner is inserted inside the insert member during blow molding, which prevents pinched portions from occurring, thereby improving strength and making it more difficult for fluid to leak between the liner and the insert member.

[0012] In addition, in the third step, it is preferable to form a sealing surface at the inlet / outlet by inserting the blow pin, which has a stepped portion on its outer peripheral surface, from the outside into the portion that becomes the inlet / outlet that contacts the inner diameter opening of the parison.

[0013] According to the present invention, the molding cycle can be shortened and the molding accuracy of the sealing surface can be increased. [Effects of the Invention]

[0014] According to the present invention, the strength is improved and the fluid is less likely to leak. High pressure A method for manufacturing a force vessel can be provided. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a vertical cross-sectional view of a pressure vessel according to a first embodiment of the present invention. FIG. [Figure 2] 1A to 1C are vertical cross-sectional views illustrating the first and second steps of a method for producing a pressure vessel according to a first embodiment of the present invention. [Figure 3] FIG. 4 is a vertical cross-sectional view illustrating a third step in the method for manufacturing a pressure vessel according to the first embodiment of the present invention. [Figure 4]FIG. 10 is a vertical cross-sectional view of the periphery of an insert member in a pressure vessel formed using a blow pin having a stepped portion in a second embodiment of the present invention. [Figure 5] FIG. 10 is a vertical cross-sectional view of the insert member and its surroundings in a state where a blow pin is inserted into the inlet of a parison in the third step of the method for producing a pressure vessel according to the second embodiment of the present invention. [Figure 6] FIG. 10 is a vertical cross-sectional view of the periphery of an insert member in a pressure vessel formed using a blow pin having a stepped portion in a third embodiment of the present invention. [Figure 7] FIG. 10 is a longitudinal cross-sectional view of a blow pin and an insert member according to a third embodiment of the present invention. [Figure 8] FIG. 10 is a vertical cross-sectional view of the insert member and its surroundings in a state in which a blow pin is inserted from an inlet of a parison in a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, several embodiments of the present invention will be described. [First embodiment] 1 is a longitudinal cross-sectional view of a pressure vessel according to a first embodiment of the present invention. In the drawings referred to below, for convenience, the upper side of the drawing may be assumed to be the upper side and the lower side of the drawing to be the lower side, but this does not limit the present invention.

[0017] As shown in Figure 1, the pressure vessel 1 according to this embodiment is a hollow vessel filled with a high-pressure fluid such as hydrogen gas. The pressure vessel 1 comprises a liner 2, an insert member 3 such as a mouthpiece, and a reinforcing layer 4. Although the pressure vessel 1 of this embodiment has insert members 3 on both the top and bottom, it is also possible to have only one of them.

[0018] The liner 2 is a hollow resin container that constitutes the inside of the pressure vessel 1. The liner 2 is formed with approximately the same thickness. The liner 2 comprises a body 21, a shoulder 22, and an inlet / outlet 23. The body 21 is cylindrical and constitutes the central portion. The shoulder 22 extends between the body 21 and the inlet / outlet 23 in a direction perpendicular to the central axis C. The shoulder 22 has an opening in the center and is circular. The inlet / outlet 23 is continuous with the opening of the shoulder 22 and is cylindrical. The inlet / outlet 23 is formed parallel to the central axis C. The inlet / outlet 23 is the portion through which fluid flows in and out.

[0019] The insert member 3 is made of metal and is a member through which fluid flows in and out of the pressure vessel 1. The insert member 3 comprises a flange portion 25 and a tubular portion 26. The flange portion 25 is ring-shaped and extends radially outward relative to the central axis C. The tubular portion 26 rises from the flange portion 25 and is cylindrical. The outer periphery of the tubular portion 26 increases in diameter toward the tip, but may decrease in diameter or may remain constant. The opening of the tubular portion 26 is referred to as an "inner diameter opening 27."

[0020] The shoulder portion 22 of the liner 2 is in surface contact with the lower surface (end surface) of the flange portion 25. Furthermore, the inlet / outlet port 23 of the liner 2 is in surface contact with the inner surface of the inner diameter opening 27 in the entire circumferential direction and in the direction of the central axis C. The liner 2 and the insert member 3 are integrally molded in a manufacturing stage described below. In other words, the liner 2 is integrally molded with the insert member 3 by inserting a parison, which is a molten resin, into the inner diameter opening 27 and performing blow molding.

[0021] The reinforcing layer 4 is a resin layer that covers the outside of the pressure vessel 1. More specifically, the reinforcing layer 4 covers parts of the body portion 21 and shoulder portion 22 of the liner 2, as well as parts of the flange portion 25 and tubular portion 26 of the insert member 3. The reinforcing layer 4 is formed, for example, by impregnating reinforcing fibers with an adhesive and then overlapping them with the inner layer by filament winding. By providing the reinforcing layer 4, the strength of the pressure vessel 1 can be increased.

[0022] Next, we will explain the method for manufacturing the pressure vessel 1 shown in Figure 1. This manufacturing method is realized by sequentially carrying out the following first to fourth steps.

[0023] (1) First step FIG. 2 is a vertical cross-sectional view illustrating the first and second steps of the method for manufacturing a pressure vessel according to the first embodiment. As shown in FIG. 2, in the first step, a pair of upper and lower insert members 3 are held in a clamped state by a pair of molding dies 31. The molding dies 31 are mold materials for blow molding the liner 2. The molding dies 31 are each movable toward or away from the central axis C. The inner surface of the molding die 31 forms a molding surface 32 for molding the liner 2. The insert members 3 are held in the molding dies 31 with their cylindrical portions 26 facing outward. Although the insert members 3 are held by the molding dies 31, they may also be held by a lifting device or other holding device.

[0024] (2)Second process After the first step, a parison 41 is inserted into each inner diameter opening 27 of each insert member 3 and into the hollow portion (cavity) within the clamped molding dies 31, 31. The parison 41 is made of molten resin and has a cylindrical shape.

[0025] (3) Third step After the second step, a blow pin (not shown) is inserted into the parison 41 and air is supplied to transfer the parison 41 to the molding surface 32 of the mold 31, the lower surface (end surface) of the flange 25 of the insert member 3, and the inner diameter opening 27 of the insert member 3, thereby performing blow molding. FIG. 3 is a vertical cross-sectional view illustrating the third step of the manufacturing method for a pressure vessel of this embodiment. As shown in FIG. 3, the parison 41 is brought into close contact with the molding surface 32, the lower surface (end surface) of the flange 25 of the insert member 3, and the inner diameter opening 27 of the insert member 3 by the supply of air. In this way, the liner 2 can be formed using the parison 41 as material. The blow pin is then removed, and the molded liner 2 is removed from the mold 31 after cooling and solidifying. Additionally, any burrs protruding from the insert member 3 are removed by cutting.

[0026] (4) 4th step After the third step, a reinforcing layer 5 is formed on the outer periphery of the liner 2 and the insert member 3 (see FIG. 1). The reinforcing layer 5 is formed by, for example, filament winding, in which reinforcing fibers impregnated with adhesive are wound around the liner 2.

[0027] According to the pressure vessel 1 and its manufacturing method described above, by inserting the parison 41 into the inner diameter opening 27, the inlet / outlet port 23 of the liner 2 after blow molding can be tightly attached to the inside of the inner diameter opening 27 with a uniform thickness. In other words, because the parison 41 is inside the inner diameter opening 27 of the insert member 3, the parison 41 that forms the inlet / outlet port 23 is not crushed by the molding dies 31 when the molding dies 31 are clamped. This prevents a pinched portion (a portion of uneven thickness caused by a pinch) from forming in the inlet / outlet port 23, thereby preventing leakage of fluids such as hydrogen gas from between the liner 2 and the insert member 3. Furthermore, because a pinched portion is not formed, the inlet / outlet port 23 can be made to have a uniform thickness, preventing stress from concentrating on one part of the inlet / outlet port 23 and improving its strength.

[0028] [Second embodiment] Each of the following embodiments basically has the structure of the pressure vessel 1 described in the first embodiment, and is manufactured by substantially the same manufacturing method. Therefore, in each of the following embodiments, explanations of the configuration common to the previous embodiments will be omitted, and the same reference numerals will be used for the same components. The second embodiment differs from the first embodiment in that it has a sealing surface on which a sealing member is installed.

[0029] FIG. 4 is a longitudinal cross-sectional view of the insert member and its surroundings in a pressure vessel formed using a blow pin with a stepped portion according to the second embodiment of the present invention. The reinforcing layer 5 is not shown. As shown in FIG. 4, a stepped portion 28 is formed at the tip of the injection / discharge port 23 in the pressure vessel 1A of the second embodiment. The injection / discharge port 23 has a constant outer diameter, as in the first embodiment. The stepped portion 28 is composed of a stepped bottom surface 28a and a stepped side surface 28b rising from the outer edge of the stepped bottom surface 28a. A sealing member 55 (e.g., an O-ring) is attached to the stepped portion 28. The stepped bottom surface 28a is the portion that forms the sealing surface of the sealing member 55. Attaching the sealing member 55 to the stepped portion 28 can prevent fluid leakage, for example, when a valve (not shown) is connected to the insert member 3.

[0030] 5 is a longitudinal cross-sectional view of the insert member and its surroundings with a blow pin inserted into the inlet of the parison in the third step of the manufacturing method for a pressure vessel according to the second embodiment of the present invention. As shown in FIG. 5, blow pin 51 has a cylindrical large-diameter portion 52 at the base end and a cylindrical small-diameter portion 53 smaller than large-diameter portion 52. The outer diameter of large-diameter portion 52 is larger than the inner diameter of parison 41 but smaller than the outer diameter. The outer diameter of large-diameter portion 52 is also smaller than inner-diameter opening 27. The outer peripheral surface of blow pin 51 and inner-diameter opening 27 form inlet / outlet port 23.

[0031] Additionally, large diameter portion 52 and small diameter portion 53 form a ring-shaped stepped portion 54. Step portion 54 is a portion that forms a sealing surface (described later) at the entrance portion of the portion that becomes injection / discharge port 23 when step portion 54 is inserted from the outside (the outside along central axis C) into the portion that becomes injection / discharge port 23 of parison 41.

[0032] When performing blow molding in the third step, a blow pin 51 is inserted into the parison 41 from the outside along the central axis C. The insertion position is the portion that will become the inlet / outlet 23 of the parison 41. At this time, the blow pin 51 is inserted so that the tip of the large diameter portion 52 is positioned below the end face of the tubular portion 26. As a result, a molding surface of the inlet / outlet 23 is formed between the outer peripheral surface of the blow pin 51 and the inner diameter opening 27. In other words, by performing blow molding in the state shown in FIG. 5, the inlet / outlet 23 is molded while the step bottom surface 28a and step side surface 28b are molded at the tip of the inlet / outlet 23 by the step portion 54.

[0033] Conventionally, to form a sealing surface, after blow molding, the tip of the injection / discharge port 23 or a part of the insert member 3 is cut off. However, this method increases the number of steps and has problems such as an unstable sealing surface and unstable sealing performance. In this regard, according to this embodiment, the seal surface (step bottom surface 28a) can be formed using the blow pin 51, so there is no need for a separate operation and the seal surface can be formed simultaneously with the blow molding process (third process). This shortens the molding cycle. Furthermore, because the seal surface is formed using the step portion 54 of the blow pin 51, the molding precision of the seal surface can be improved and the sealing performance can be stabilized.

[0034] [Third embodiment] The third embodiment differs from the first embodiment in that it includes a seal surface on which a seal member is installed, and also differs from the second embodiment in the structure of the seal surface.

[0035] Fig. 6 is a vertical cross-sectional view of the insert member and its surroundings in a pressure vessel formed using a blow pin with a stepped portion in a third embodiment of the present invention. As shown in Fig. 6, the injection / discharge port 23 has a base portion 23a and an expanded diameter portion 23b that is larger in diameter than the base portion 23a. The base portion 23a and the expanded diameter portion 23b form a stepped portion 54. The stepped portion 54 is composed of a stepped bottom surface 54a and a stepped side surface 54b that rises from the outer edge of the stepped bottom surface 54a. A sealing member 55 (e.g., an O-ring) is attached to the stepped portion 54. The stepped bottom surface 54a is the portion that forms the sealing surface of the sealing member 55.

[0036] A step portion 29 is formed on the inside of the cylindrical portion 26 of the insert member 3. The step portion 29 is composed of a step bottom surface 29a and a step side surface 29b rising from the outer edge of the step bottom surface 29a. The step portion 54 of the inlet / outlet 23 is in close contact with the shape of the step portion 29 of the insert member 3.

[0037] FIG. 7 is a longitudinal cross-sectional view of a blow pin and an insert member according to a third embodiment of the present invention. FIG. 8 is a longitudinal cross-sectional view of the insert member and its surroundings, showing the blow pin according to the third embodiment of the present invention inserted into the inlet of the parison. As shown in FIG. 7, the blow pin 71 has a large diameter portion 72, a medium diameter portion 73, and a small diameter portion 74. The large diameter portion 72 and the medium diameter portion 73 form a first step portion 75. The medium diameter portion 73 and the small diameter portion 74 form a second step portion 76. The outer diameter of the large diameter portion 72 is the same as the outer diameter of the step side surface 29b of the step portion 29. The outer diameter of the medium diameter portion 73 is the same as the inner diameter of the inner diameter opening 27. The height of the medium diameter portion 73 is smaller than the height of the step side surface 29b of the step portion 29. The area surrounded by the insert member 3 and the outer peripheral surface of the blow pin 71 is the portion where the inlet / outlet port 23 is formed. The second step portion 76 is a portion that forms a step bottom surface 54a that serves as a sealing surface when the parison 41 is pressed in.

[0038] As shown in Figure 8, when blow molding is performed in the third step, a blow pin 71 is inserted from the inside of the parison 41 and from the outside along the central axis C. At this time, the blow pin 71 is inserted so that the tip of the large diameter portion 72 is flush with the end face of the tubular portion 26. The injection / discharge port 23 is formed by the area surrounded by the insert member 3 and the outer peripheral surface of the blow pin 71. At the same time, a step portion 54 where a seal member 55 is to be disposed is also formed.

[0039] According to this embodiment, the sealing surface (step bottom surface 54a) can be formed using the blow pin 71, so there is no need for a separate operation and the sealing surface can be formed simultaneously with the blow molding process (third process). This shortens the molding cycle. Furthermore, since the sealing surface is formed using the first step portion 75 and the second step portion 76 of the blow pin 71, the molding precision of the sealing surface can be improved and the sealing performance can be stabilized. Furthermore, the blow pin 71 can form the expanded diameter portion 23b at the inlet / outlet port 23.

[0040] Although the embodiments of the present invention have been described above, appropriate design changes are possible within the scope of the present invention. [Explanation of symbols]

[0041] 1, 1A, 1B Pressure vessel 2 liner 3 Insert material 23 Inlet / outlet 27 Inner diameter opening 31 Molding mold 41 Parison 51,71 Blowpin

Claims

1. a first step of holding a cylindrical insert member having an inner diameter opening; a second step of inserting a parison into the inner diameter opening of the insert member and into the mold; a third step of blow-molding the parison by supplying air through a blow pin after the second step and transferring the parison to the molding surface and the inner diameter opening of the mold.

2. 2. The method for manufacturing a pressure vessel according to claim 1, wherein the third step comprises inserting the blow pin, which has a stepped portion on its outer circumferential surface, from the outside into a portion of the parison that will become an inlet / outlet port and that contacts the inner diameter opening, thereby forming a sealing surface at the inlet / outlet port.

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