Method and device for manufacturing hollow body

Abstract

To solve the problem of voids occurring in a fiber layer formed by winding resin-impregnated fibers around a mandrel, which reduces a strength of the fiber layer after curing.SOLUTION: A method for manufacturing a hollow body using a mandrel includes: an impregnation step of impregnating resin into a fiber; a winding step of winding the resin-impregnated fiber onto a surface of the mandrel; and a load application step of applying a load by pressing a roller against a fiber layer formed on the surface of the mandrel in the winding step.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a method and apparatus for manufacturing a hollow body using a mandrel. [Background technology]

[0002] Patent Document 1 discloses a technique for winding a fiber-reinforced resin member around the outer peripheral surface of a high-pressure vessel, which is an object to be braided, using a braiding machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-50433 Summary of the Invention [Problem to be solved by the invention]

[0004] When fibers are wound around an object, air can be trapped inside the fiber layer formed on the surface of the object, creating numerous tiny gaps known as voids. These voids reduce the strength of the fiber layer after curing. Therefore, improvements are needed to improve the strength of such fiber layers. [Means for solving the problem]

[0005] This specification discloses a method for manufacturing a hollow body using a mandrel, the method comprising: an impregnation step of impregnating fibers with a resin, a winding step of winding the resin-impregnated fibers around the surface of the mandrel, and a loading step of applying a load by pressing a roller against the fiber layer formed on the surface of the mandrel by the winding step.

[0006] According to the above configuration, the fiber layer is compressed by the loading step, and the air in the voids in the fiber layer is pushed out of the fiber layer, thereby improving and stabilizing the strength of the fiber layer formed on the surface of the mandrel after curing. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a simplified diagram showing a hollow body manufacturing system. [Figure 2] FIG. 2 is a partial cross-sectional view showing a simplified view of a part of the hollow body manufacturing system. [Figure 3] FIG. 1 is a diagram showing multiple rollers from a front-to-rear perspective. [Figure 4] FIG. [Figure 5] FIG. 10 is a diagram showing an image of a cross section of a conventional hollow body. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present embodiment will be described with reference to the drawings. Each drawing is merely an example, and the present embodiment is not limited to the contents shown in the drawings. Also, since each drawing is an example, the shapes shown may not be accurate, and some parts may be omitted.

[0009] FIG. 1 shows a simplified view of a hollow body manufacturing system 1 according to this embodiment. FIG. 2 shows a simplified partial cross-sectional view of a portion of the hollow body manufacturing system 1, enlarged from FIG. 1. The figures include portions where the shapes and the like do not match. For example, the shape of the end of the mandrel 10 differs between FIG. 1 and FIG. 4, but either shape is acceptable, and such inconsistency does not affect the explanation of the present case. At least a portion of the hollow body manufacturing system 1 realizes a method for manufacturing a hollow body using the mandrel 10. Furthermore, at least a portion of the hollow body manufacturing system 1 corresponds to an apparatus for manufacturing a hollow body using the mandrel 10. Simply put, the hollow body manufacturing system 1 may be considered as this apparatus.

[0010] According to FIG. 1, the hollow body manufacturing system 1 includes a robot arm 20 for supporting and moving a mandrel 10. The mandrel 10 is a hollow, cylindrical member, and corresponds to, for example, the inner layer (liner) of a tank as a hollow body. As a more specific example, the mandrel 10 is formed from a resin such as nylon, and serves as the inner layer of a high-pressure tank for storing hydrogen or the like. A support shaft 21 that is coaxial with the horizontal Z axis passes through the mandrel 10. The mandrel 10 and the support shaft 21 can be considered to be coaxial. In each drawing, one side of the Z axis direction is considered to be the front, and the other side is considered to be the rear.

[0011] A jig shaft 22 extending along the Z-axis is attached to the tip of the robot arm 20, and the jig shaft 22 coaxially holds the support shaft 21. As shown by the two-dot chain line in FIG. 1 , at least a portion of the robot arm 20 moves forward, thereby moving the jig shaft 22, support shaft 21, and mandrel 10 forward along the Z-axis. In other words, the mandrel 10 moves from rear to front on the Z-axis. The hollow body manufacturing system 1 may appropriately include a jig receiving portion 23 or the like that supports the long jig shaft 22 to keep it horizontal. A pressure higher than the external atmospheric pressure is applied inside the mandrel 10, and the gap between the support shaft 21 and the mandrel 10 is sealed to prevent air from leaking from inside the mandrel 10.

[0012] The hollow body manufacturing system 1 includes a winding machine 30, an impregnation machine 40, a removal machine 50, and rollers 60. The winding machine 30 is a machine for winding a wire rod, to which a predetermined tension has been applied, in a mesh pattern around the surface of an object to be wound. The winding machine 30 has a bobbin or the like around which the wire rod is wound. The winding machine 30 is also called a braiding machine, braider, or the like. Although simplified in FIG. 1 , the winding machine 30 is formed in a ring shape surrounding the Z axis and supplies multiple wire rods to the mandrel 10 from around the mandrel 10. Rollers, rings, or the like are appropriately provided around the winding machine 30 or between the winding machine 30 and the mandrel 10 to apply the necessary tension to the wire rod. The ring 90 is one such ring. The configuration and function of the winding machine 30 are known, so details will be omitted. In this embodiment, the winding machine 30 supplies fiber 31 (e.g., carbon fiber) to the mandrel 10.

[0013] Resin R is supplied to the impregnation machine 40 by pressure from a pump (not shown). The impregnation machine 40 is also formed in a ring shape so as to surround the mandrel 10 moving on the Z axis, and impregnates each fiber 31 supplied to the mandrel 10 by the winding machine 30 with resin R at a timing before each fiber 31 reaches the mandrel 10. In other words, the impregnation machine 40 performs an "impregnation step" in which the fibers 31 are impregnated with resin R. The fibers 31 impregnated with resin R are wound in a net-like pattern around the surface of the mandrel 10. As a result, the winding machine 30 performs a "winding step" in which the fibers 31 impregnated with resin R are wound around the surface of the mandrel 10.

[0014] Through the winding process, a fiber layer 32 is formed on the surface of the mandrel 10. As described above, pressure is applied within the mandrel 10, which prevents the mandrel 10 from being dented or distorted during the winding process or the loading process described below. Furthermore, if the fiber 31 is carbon fiber, the fiber layer 32 will be a carbon fiber reinforced plastics (CFRP) layer made of carbon fiber and resin R.

[0015] A remover 50 is disposed at a predetermined position forward of the winding position where the fiber 31 is wound around the mandrel 10. Furthermore, a roller 60 is disposed at a predetermined position forward of the remover 50. However, the illustration of the remover 50 is omitted in FIG. 2. As the mandrel 10 moves forward, the portion of the mandrel 10 on which the fiber layer 32 is formed passes the position of the remover 50 and then passes the position of the roller 60. Although details are omitted, the hollow body manufacturing system 1 may appropriately have a pedestal 91 on which each component is mounted or supported in order to support the remover 50 and the like at a required height.

[0016] The remover 50 is annularly formed and has a circular hole 51 (see FIG. 4 ) coaxial with the Z axis through which the mandrel 10 can pass. The circular hole 51 is formed, for example, in a rubber membrane. When the mandrel 10 on which the fiber layer 32 has been formed passes through the circular hole 51 of the remover 50, the surface of the fiber layer 32 comes into contact with the edge of the circular hole 51, thereby removing the resin R that did not pass through the circular hole 51, i.e., the excess resin, from the fiber layer 32. As described above, this embodiment includes a "removal step" in which the mandrel 10 on which the fiber layer 32 has been formed is passed through the annular remover 50, and the excess resin is removed from the fiber layer 32 by the remover 50. The removal step adjusts the thickness of the fiber layer 32 to a substantially uniform value. The base 91 also serves as a resin receiver for receiving the excess resin removed by the remover 50.

[0017] The roller 60 is a means for realizing a "loading step" in which the roller 60 presses against the fiber layer 32 to apply a load to the fiber layer 32. The roller 60 applies a load to the fiber layer 32 by the force of an elastic body such as a spring. When the roller 60 comes into contact with the fiber layer 32, the roller 60 can rotate in accordance with the movement of the mandrel 10 along the Z axis.

[0018] FIG. 3 shows the rollers 60 from a perspective looking from the front to the rear. In this embodiment, multiple rollers 60 are arranged in a ring shape around the Z axis so as to surround the periphery of the mandrel 10. The mandrel 10, on which the fiber layer 32 is formed, passes through the central ring formed by the multiple rollers 60. As a result, the fiber layer 32 is compressed approximately evenly from the periphery by the multiple rollers 60. Furthermore, according to the positional relationship between the remover 50 and the rollers 60 shown in FIG. 1, in the loading step, the rollers 60 are pressed against the fiber layer 32 from which excess resin has been removed by the remover 50, and a load is applied.

[0019] As shown in FIG. 1, in the hollow body manufacturing system 1, a hot air heater 70 is installed near the roller 60 and ahead of the winding position where the fiber 31 is wound around the mandrel 10. The hot air heater 70 prevents the resin R from cooling and solidifying by blowing hot air onto the fiber layer 32 that is the target of the removing process or loading process. The number of hot air heaters 70 is not limited to one. It is of course possible to move the hot air heater 70 and adjust the temperature and volume of the hot air as needed.

[0020] 5 is an image of a cross section of a conventional hollow body, showing the mandrel 100 and the fiber layer 320. The fiber layer 320 is formed on the outside of the mandrel 100. As described above, air is entrained when the fiber is wound around the object. As a result, voids 321 are formed in the fiber layer 320 formed on the surface of the mandrel 100, and these voids 321 are a factor in reducing the strength of the fiber layer 320 after curing.

[0021] To address these issues, the method of this embodiment includes an impregnation step and a winding step, and further includes a loading step in which a roller 60 is pressed against the fiber layer 32 formed on the surface of the mandrel 10 to apply a load. With this configuration, the fiber layer 32 is compressed by the loading step, and air in voids within the fiber layer 32 is forced out of the fiber layer 32. In other words, the voids are not trapped within the fiber layer 32. Therefore, the strength of the fiber layer 32 formed on the surface of the mandrel 10 after curing is improved and stabilized. Furthermore, according to this embodiment, the loading step and the removal step are combined, making it possible to remove the voids within the fiber layer 32 together with the excess resin.

[0022] 4 is an enlarged partial cross-sectional view of the vicinity of the roller 60. The hollow body manufacturing system 1 may include an outer diameter measurement unit 80 that measures the outer diameter of the mandrel 10 including the fiber layer 32 at a predetermined position forward of the roller 60. The outer diameter measurement unit 80 measures the outer diameter of the mandrel 10 including the fiber layer 32 after the roller 60 has been pressed against it. The outer diameter measurement method by the outer diameter measurement unit 80 may be any method, such as contact measurement or non-contact measurement. The outer diameter measurement value by the outer diameter measurement unit 80 is sent to the roller control unit 81.

[0023] The roller control unit 81 can adjust the load applied by the roller 60 to the fiber layer 32, and includes, for example, an actuator that changes the position of the roller 60. The roller control unit 81 compares the measurement value by the outer diameter measurement unit 80 with a design value for the outer diameter of the mandrel 10 including the fiber layer 32, and adjusts the load applied by the roller 60 so that the difference between the measurement value and the design value is as close to zero as possible. The adjustment of the load applied by the roller 60 is performed, for example, by changing the distance from the Z axis to the roller 60. As described above, in the loading step, the outer diameter of the mandrel 10 including the fiber layer 32 pressed against it by the roller 60 is measured, and the load applied by the roller 60 is adjusted according to the measured outer diameter. With this configuration, the measured outer diameter value is fed back to the pressing of the fiber layer 32 by the roller 60, thereby stabilizing the thickness of the fiber layer 32 and the strength of the fiber layer 32 after curing.

[0024] The positional relationship between the remover 50 and the roller 60 is not limited to the illustrated embodiment. The remover 50 may be disposed at a predetermined position ahead of the roller 60. In a configuration in which the remover 50 is disposed ahead of the roller 60, the fiber layer 32 compressed by the application of a load by the roller 60 becomes the target of the removal process, and the excess resin is removed by the remover 50.

[0025] The category disclosed in this embodiment is not limited to methods. An apparatus for manufacturing a hollow body using a mandrel 10 includes an impregnation machine 40 that impregnates fibers 31 with resin R, a winding machine 30 that winds fibers 31 impregnated with resin R around the surface of the mandrel 10, and a roller 60 that applies a load to fiber layer 32 by pressing against fiber layer 32 formed on the surface of the mandrel 10 by winding machine 30.

[0026] According to the present embodiment, the mandrel 10, together with the outer fiber layer 32, constitutes a hollow body such as a high-pressure tank. However, the mandrel 10 may not be included in the hollow body that is ultimately manufactured. In other words, the hollow body to be manufactured refers to the fiber layer 32 formed on the outside of the mandrel 10 or a product that includes the fiber layer 32, and the mandrel 10 may be a mold used in the process of manufacturing such a hollow body.

[0027] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of those objectives itself has technical utility. [Explanation of symbols]

[0028] 1: hollow body manufacturing system, 10: mandrel, 20: robot arm, 21: support shaft, 22: jig shaft, 30: winding machine, 31: fiber, 32: fiber layer, 40: impregnation machine, 50: removal machine, 51: circular hole, 60: roller, 70: hot air heater, 80: outer diameter measuring unit, 81: roller control unit

Claims

1. 1. A method for manufacturing a hollow body using a mandrel, comprising the steps of: an impregnation step of impregnating the fibers with a resin; a winding step of winding the resin-impregnated fiber onto a surface of the mandrel; a loading step of applying a load by pressing a roller against the fiber layer formed on the surface of the mandrel by the winding step.

2. The method according to claim 1 , wherein the loading step includes measuring an outer diameter of the mandrel including the fiber layer pressed against the roller, and adjusting the load applied by the roller in accordance with the outer diameter.

3. The method of claim 1 , further comprising a removing step of passing the mandrel on which the fibrous layer is formed through an annular remover to remove excess resin from the fibrous layer with the remover.

4. The method of claim 1 , wherein the mandrel is an inner layer of a high-pressure tank.

5. An apparatus for manufacturing a hollow body using a mandrel, comprising: an impregnation machine for impregnating resin into fibers; a winding machine that winds the resin-impregnated fiber onto a surface of the mandrel; a roller that presses against the fiber layer formed on the surface of the mandrel by the winding machine, thereby applying a load to the fiber layer.

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