JP7765259B2 - Method for manufacturing fiber-reinforced resin pipe body - Google Patents

Description

The present invention relates to a method for manufacturing a fiber-reinforced resin pipe body , for example, a power transmission shaft in a vehicle.

A power transmission shaft (propeller shaft) mounted on a vehicle has a tubular body extending in the longitudinal direction of the vehicle, and this tubular body transmits power generated by the prime mover and reduced in speed by the transmission to the final drive unit. Tubes used in such power transmission shafts include those made of fiber-reinforced plastic manufactured using a mandrel (see Patent Document 1 below).

Japanese Patent Application Publication No. 3-265738

Methods for winding material around a mandrel include the filament winding method, in which continuous fibers impregnated with resin are wound, and the sheet winding method, in which prepreg (a sheet made of fibers impregnated with resin) is wound. To harden the resin impregnated in the fibers wound using the filament winding method, the mandrel around which the material is wound is placed in a mold and filled with a fluid, thereby increasing the pressure inside the mandrel and heating the resin. A component with a fluid flow path is placed at the end of the mandrel, but if the mandrel deforms due to heating, a gap forms between the component and the mandrel, allowing the fluid to leak. This can prevent the pressure inside the mandrel from increasing, potentially reducing the molding precision of the product.

The present invention was created to solve these problems, and its objective is to provide a method for manufacturing a fiber-reinforced resin pipe using a mandrel that can prevent leakage of fluid used to increase internal pressure.

According to the present disclosure, there is provided a method for manufacturing a fiber-reinforced resin pipe using a mandrel including a cylindrical mandrel body, an inner fitting member fitted into an axial end of the mandrel body, and an embedded member embedded in the axial end of the mandrel body, the method including: an arrangement step of arranging a fiber layer on an outer peripheral surface of the mandrel; an impregnation step of impregnating the fiber layer arranged on the outer peripheral surface of the mandrel with a thermosetting resin; and a curing step of filling the mandrel body with a fluid by flowing the fluid into the mandrel body through a flow path formed in the inner fitting member and heating the thermosetting resin to harden it, wherein in the hardening step, the embedded member suppresses deformation of the portion of the mandrel body where the embedded member is embedded, thereby preventing the fluid from leaking from between the inner fitting member and the mandrel body.

According to the present invention, it is possible to provide a method for manufacturing a fiber-reinforced resin pipe using a mandrel that can prevent leakage of a fluid for increasing the internal pressure.

FIG. 1 is a cross-sectional view schematically showing a mandrel according to a first embodiment of the present invention. 1 , which is a cross-sectional view schematically showing the end of the mandrel body, the inner fitting member, and the embedded member. FIG. 1 is a diagram schematically illustrating a power transmission shaft manufactured using a mandrel according to a first embodiment of the present invention. FIG. 1 is a cross-sectional view schematically showing a power transmission shaft according to a first embodiment of the present invention. 1A to 1C are schematic views for explaining a method for manufacturing a power transmission shaft according to a first embodiment of the present invention. 1A to 1C are schematic views for explaining a method for manufacturing a power transmission shaft according to a first embodiment of the present invention. 1A to 1C are schematic views for explaining a method for manufacturing a power transmission shaft according to a first embodiment of the present invention. 3 is a flowchart illustrating a method for manufacturing a power transmission shaft according to a first embodiment of the present invention. 1A to 1C are schematic views for explaining a method for manufacturing a power transmission shaft according to a first embodiment of the present invention. FIG. 4 is a partially enlarged cross-sectional view schematically showing a mandrel according to a second embodiment of the present invention. FIG. 10 is a partially enlarged cross-sectional view schematically showing a mandrel according to a third embodiment of the present invention. FIG. 10 is a partially enlarged cross-sectional view schematically showing a mandrel according to a fourth embodiment of the present invention. FIG. 10 is a partially enlarged cross-sectional view schematically showing a mandrel according to a fifth embodiment of the present invention. FIG. 10 is a partially enlarged cross-sectional view schematically showing a mandrel according to a sixth embodiment of the present invention.

Embodiments of the present invention will be described in detail with reference to the drawings, taking as an example the case of manufacturing a vehicle power transmission shaft (propeller shaft) using carbon fiber reinforced plastic. In the following description, identical elements will be given the same reference numerals, and duplicate explanations will be omitted. The drawings referred to have been exaggerated for clarity.

First Embodiment
As shown in FIG. 1, the mandrel 1A according to the first embodiment is used to manufacture a fiber-reinforced resin pipe 40 (see FIG. 3), and includes a mandrel body 10, an inner fitting member 20A, and an embedded member 30A.

<Mandrel body>
The mandrel body 10 is a cylindrical resin member. In this embodiment, the mandrel body 10 is removed from the interior of the fiber-reinforced resin pipe 40, but it can also remain inside the fiber-reinforced resin pipe 40 and function as a core material for the fiber-reinforced resin pipe 40. The mandrel body 40 can be made of a material that can withstand the heat generated during resin curing in the fiber-reinforced resin pipe 40. Examples of such materials include PP (polypropylene resin), PET (polyethylene terephthalate resin), and SMP (shape memory polymer). The mandrel body 10 integrally includes a large-diameter section 11 in an axially intermediate portion, a tapered section 12 and a medium-diameter section 13 formed at one axial end, and a step section 14 and a small-diameter section 15 formed at the other axial end. In this embodiment, a protrusion 16 having a diameter smaller than that of the medium-diameter section 13 is formed at one axial end of the medium-diameter section 13. The protrusion 16 is a portion onto which the first metal member 30 is fitted.

<Inner fittings>
As shown in Figure 2, the inner fitting member 20A is a cylindrical metal member fitted into the small-diameter portion 15, which is the other axial end of the mandrel body 10. The inner fitting member 20A prevents the small-diameter portion 15 from deforming radially inward, and has a flow path 20a formed therein for filling the mandrel body 10 with a pressurizing fluid F (see Figure 9) (e.g., pressurized air). In this embodiment, the pressurizing fluid F is used to pressurize and expand the mandrel body 10 within the molding apparatus 100. The pressurizing fluid F also serves as a heating fluid for heating and curing a thermosetting resin (resin 44, described below) arranged on the outer circumferential surface of the mandrel body 10 within the molding apparatus 100, described below.

<Buried materials>
The embedded member 30A is an annular (cylindrical) metal member embedded in the small-diameter portion 15, which is the other axial end of the mandrel body 10. The embedded member 30A has an annular shape that extends throughout the entire circumferential direction within the mandrel body 10. By suppressing deformation of the embedded portion, the embedded member 30A suppresses the generation of a gap between the outer circumferential surface of the inner fitting member 20A and the inner circumferential surface of the mandrel body 10. The embedded member 30A exhibits this gap generation suppression function at a temperature (preferably from room temperature to the above-mentioned heating temperature) when heated to harden the thermosetting resin disposed on the outer circumferential surface of the mandrel body. One axial end of the embedded member 30A is located axially intermediate of the one axial end of the inner fitting member 20A. The other axial end of the embedded member 30A is located at the same axial position as the other axial end of the mandrel body 10.

The inner fitting member 20A and the embedded member 30A are harder than the mandrel body 10 when the mandrel 1A is heated to a predetermined temperature (e.g., 140°C) by the heating fluid in the molding process of step S9 described below. Furthermore, from the standpoint of linear expansion, it is preferable that the embedded member 30A be made of the same metal material as the inner fitting member 20A.

<Power transmission shaft>
3 and 4, the power transmission shaft 2 manufactured using the mandrel 1A (see FIG. 1) is a shaft that extends in the fore-and-aft direction of a vehicle and transmits power generated by a power source as rotation about an axis. The power transmission shaft 2 includes a fiber-reinforced resin pipe body 40, a first metal member 50, and a second metal member 60.

<Fiber reinforced resin tube body>
The fiber-reinforced resin pipe 40 is a resin-containing fiber layer formed in a tubular shape to fit along the outer peripheral surface of the mandrel body 10. The fiber-reinforced resin pipe 40 is formed to fit along the outer peripheral surfaces of the large-diameter section 11, the tapered section 12, and the medium-diameter section 13 of the mandrel body 10, one axial end of the first metal member 50, and the other axial end of the second metal member 60. As shown in FIGS. 5 to 7 , the fiber-reinforced resin pipe 40 includes, as carbon fiber layers, a first carbon fiber layer 41, a second carbon fiber layer 42, and a third carbon fiber layer 43, in this order from the radially inner side (the mandrel body 10 side). Note that only a portion of the carbon fiber layers 41, 42, and 43 are shown in FIGS. 5 to 7 . In addition, the outer peripheral surface of one axial end of the first metal member 50 (the end located opposite the mandrel body 10) and the outer peripheral surface of the other axial end of the second metal member 60 (the end located opposite the mandrel body 10) are not covered by the fiber-reinforced resin pipe body 40 and protrude from the fiber-reinforced resin pipe body 40.

<First carbon fiber layer>
5, the first carbon fiber layer 41 is made up of a plurality of carbon fibers that are provided on the outer peripheral surface of the mandrel body 10, etc., so as to cover the mandrel body 10. The carbon fibers in the first carbon fiber layer 41 extend parallel to the axial direction of the mandrel body 10. That is, the orientation angle of the carbon fibers in the first carbon fiber layer 41 with respect to the axis X of the mandrel body 10 is 0°.

<Second carbon fiber layer>
6, the second carbon fiber layer 42 is provided radially outward of the first carbon fiber layer 41 and is composed of a plurality of carbon fibers provided so as to cover the first carbon fiber layer 41. The carbon fibers in the second carbon fiber layer 42 are wound one or more times so as to be inclined at 45° with respect to the axial direction of the mandrel body 10, and extend spirally with respect to the axial direction of the mandrel body 10. That is, with respect to the second carbon fiber layer 42, the orientation angle of the carbon fibers with respect to the axis X of the mandrel body 10 is 45°.

<Third carbon fiber layer>
7, the third carbon fiber layer 43 is provided radially outward of the second carbon fiber layer 42 and is composed of a plurality of carbon fibers provided so as to cover the second carbon fiber layer 42. The carbon fibers in the third carbon fiber layer 43 are wound one or more times so as to be inclined at a −45° angle with respect to the axial direction of the mandrel body 10, and extend in a spiral shape with respect to the axial direction of the mandrel body 10. That is, with respect to the third carbon fiber layer 43, the orientation angle of the carbon fibers with respect to the axis X of the mandrel body 10 is −45°.

As shown in Figures 3 and 4, the fiber-reinforced resin tube 40 has a tapered section 40b formed at one axial end, which tapers from the large-diameter section 40a at the axial center toward the small-diameter section 40c at one axial end. The large-diameter section 40a is a main body section that has a shape that follows the outer peripheral surface of the large-diameter section 11 of the mandrel body 10. The tapered section 40b has a shape that follows the outer peripheral surface of the tapered section 12 of the mandrel body 10. The small-diameter section 40c is an end section that has a shape that follows the outer peripheral surfaces of the medium-diameter section 13 of the mandrel body 10 and part of the first metal member 50.

<First Metal Member>
The first metal member 50 is a member (shaft) having a substantially cylindrical shape. As shown in Figure 7 and other figures, during the manufacturing process, one axial end of the first metal member 50 located away from the mandrel body 10 protrudes from the mandrel body 10, and the other axial end of the first metal member 50 located on the mandrel body 10 side is fitted (internal fit) into the mandrel body 10.

As shown in Figures 1 and 3, the other axial end of the first metal member 50 is formed with a bottomed hole 50a into which the protrusion 16 of the mandrel body 10 can be inserted.

The first metal member 50 is one component of the plunge joint assembly on the power transmission shaft 2. The plunge joint assembly is formed by assembling a boot and plunge joint (both not shown) to the first metal member 50.

<Second Metal Member>
The second metal member 60 is a member having a substantially cylindrical shape. As shown in Figure 7 and other figures, during the manufacturing process, the other axial end of the second metal member 60 located away from the mandrel body 10 protrudes from the mandrel body 10, and one axial end of the second metal member 60 located on the mandrel body 10 side is fitted (externally fitted) to the mandrel body 10.

The second metal member 60 is one component of the yoke assembly on the power transmission shaft 2. The yoke assembly is formed by assembling a spider, needle bearing, and yoke (all not shown) to the second metal member 60.

<Manufacturing method>
Next, a method for manufacturing a power transmission shaft 2 using a mandrel 1A according to a first embodiment of the present invention will be described with reference to the flowchart of FIG. 8 . The method for manufacturing the power transmission shaft 1 includes a mandrel body forming step (step S1), an inner fitting member installation step (step S2) performed after the mandrel body forming step, a first connecting step (step S3) performed after the inner fitting member installation step, and a second connecting step (step S4) performed after the first connecting step. The method for manufacturing the power transmission shaft 2 also includes a fiber installation step (steps S5 to S7) performed after the second connecting step, and a mold installation step (step S8) performed after the fiber installation step. The method for manufacturing the power transmission shaft 2 also includes a molding step (step S9) performed after the mold installation step, a removal step (step S10) performed after the molding step, and a joint assembly step (step S11) performed after the removal step.

Step S1 is a process for forming the resin mandrel body 10 shown in Figures 1 and 2 using a molding device (not shown). In step S1, the embedding member 30 is integrally molded by insert molding in a state where it is embedded within the mandrel body 10.

Following step S1, in step S2, the inner fitting member 20A is press-fitted into the small diameter portion 15 of the mandrel body 10. During press-fitting, a lubricant such as grease may be applied between the outer surface of the inner fitting member 20A and the outer surface of the small diameter portion 15. Note that step S2 may be performed before step S8.

Following step S2, in step S3, a first metal member 50 is provided on one axial end of the mandrel body 10. In step S3, the other axial end of the first metal member 50 is first fitted (externally attached) to the protruding portion 16 of the mandrel body 10. Next, an adhesive layer (not shown) is provided on the outer peripheral surface of the other axial end of the first metal member 50. In step S3, the first metal member 50 is fitted onto the protruding portion 16 of the mandrel body 10.

Following step S3, in step S4, a second metal member (collar) 60 is provided at the other axial end of the mandrel body 10. In step S4, the second metal member 60 is fitted onto the stepped portion 14 of the mandrel body 10. The order of steps S3 and S4 can be changed as appropriate; step S4 may be performed first, or steps S3 and S4 may be performed simultaneously.

Following step S4, in step S5, a first carbon fiber layer 41 is formed on the outer peripheral surfaces of the mandrel body 10, the first metal member 50, and the second metal member 60, as shown in FIG. 5. Following step S5, in step S6, a second carbon fiber layer 42 is formed on the outer peripheral surfaces of the first carbon fiber layer 41 of the mandrel body 10, the first metal member 50, and the second metal member 60, as shown in FIG. 6. Following step S6, in step S7, a third carbon fiber layer 43 is formed on the outer peripheral surfaces of the second carbon fiber layer 42 of the mandrel body 10, the first metal member 50, and the second metal member 60, as shown in FIG. 7. In steps S5 to S7, carbon fiber layers 41 to 43 are formed on the axial ends of the first metal member 50 and the second metal member 60 opposite the mandrel 10, so that no fibers are present.

In steps S5 to S7, the carbon fiber layers 41 to 43 are not resin-impregnated fibers but rather raw silk. The carbon fiber layers 41 to 43 are arranged on the outer peripheral surfaces of the other axial ends of the mandrel body 10, first metal member 50, and second metal member 60 using a multi-yarn filament winding method. The carbon fiber layers 41 to 43, which are fed using the multi-yarn filament winding method, are independent layers that are not woven together, exhibiting a so-called non-crimp structure.

Following step S7, in step S8, the assembly of the mandrel 1A, first metal member 50, second metal member 60, and each carbon fiber layer 41-43 is placed in the molding device (mold) 100, as shown in FIG. 9.

Following step S8, resin 44 is supplied into the molding device 100. This allows the carbon fiber layers 41-43 arranged on the outer circumferential surface of the mandrel body 10 to be impregnated with the resin 44. Heat is then applied to the molding device 100 to harden the resin 44, forming the fiber-reinforced resin pipe 40, and the fiber-reinforced resin pipe 40, first metal member 50, and second metal member 60 are integrally molded (step S9, molding process). The resin 44 is, for example, a thermosetting resin. In this embodiment, the mold of the molding device 100 is divided into multiple sections. In step S9, heat is applied to the assembly, and a mold closing operation is performed to close the mold of the molding device 100. Subsequently, a mold clamping operation is performed to apply pressure to the closed mold, thereby increasing the pressure within the mold and promoting the hardening of the resin 44. Note that this embodiment describes a configuration in which the mold is divided into multiple sections, and therefore mold closing and mold clamping operations are performed, but the mold clamping operation is not required. Furthermore, if the mold is not divided into multiple sections, such mold closing and clamping operations are not required. Within the molding device 100, a space (resin pool 102) is formed on the outlet side of the gate 101, through which the molten resin 44 is introduced. The resin 44 introduced into the molding device 100 is stored in the resin pool 102, located to the side of one axial end of the carbon fiber layers 41-43. The resin 44 stored in the resin pool 102 moves in the axial direction of the mandrel body 10 by vacuum suction from a suction port 103 formed on the opposite side of the gate 101 in the arrangement direction of the carbon fiber layers 41-43 (on the outer peripheral surface side of the other axial end of the carbon fiber layers 41-43), and impregnates the carbon fiber layers 41-43. With the resin 44 impregnated into the carbon fiber layers 41-23, heat is applied to the molding device 100, and pressure is further applied within the molding device 100, thereby forming the fiber-reinforced resin pipe 40.

As shown in FIG. 9 , the molding apparatus 100 of the first embodiment is provided with a communication passage 104 that communicates with the inside of the mandrel body 10 via the flow path 20a. During the molding process, the hollow portion of the mandrel body 10 is filled with a pressurizing fluid F (e.g., pressurized air at 140°C or higher) via the communication passage 104, which is connected to a supply device (not shown). The mandrel body 10 is heated by the high-temperature pressurizing fluid F and softens when it reaches a temperature lower than the temperature at which the resin 44 hardens (its transformation temperature of 80°C). The mandrel body 10 is then pressurized from the inside by the pressurizing fluid F, expanding and deforming to conform to the inner circumferential surface of the molding apparatus 100. This pressurization prevents the mandrel body 10 from being deformed in a radial direction by the filled resin 44. Furthermore, this pressurization reduces the amount of resin 44 filled, preventing an increase in the weight of the finished fiber-reinforced resin pipe 40.

If the mandrel body 10 becomes soft and easily deformed due to heating by the high-temperature pressurizing fluid F, there is a risk that the pressurizing fluid F will leak out of the mandrel body 10 from between the outer surface of the inner fitting member 20A and the inner surface of the small diameter portion 15 of the mandrel body 10. In the mandrel 1A according to the first embodiment, the hardness of the embedding member 30A embedded in the small diameter portion 15 of the mandrel body 10 is higher than the hardness of the mandrel body 10 in a heated environment, thereby suppressing deformation of the small diameter portion 15 and preventing leakage of the heating fluid F. This relationship in which the hardness of the embedding member 30A is higher than the hardness of the mandrel body 10 holds true from room temperature to the temperature at which the resin 44 hardens.

Furthermore, in the mandrel 1A according to the first embodiment, the thickness of the portion 15a of the mandrel body 10 between the inner fitting member 20A and the embedded member 30A is smaller than the thickness of the mandrel body 10 (the entire small diameter portion 15) between the inner fitting member 20A and the mold 100. Therefore, the mandrel 1A effectively suppresses deformation of the mandrel body 10, which could create a gap between the inner fitting member 20A and the mold 100, and prevents leakage of the pressurizing fluid F.

Furthermore, in the mandrel 1A according to the first embodiment, one axial end of the embedded member 30A is located closer to the center in the axial direction than one axial end of the inner fitting member 20A. Therefore, the mandrel 1A effectively suppresses deformation of the mandrel body 10 on the hollow portion side of the mandrel body 10, preventing leakage of the pressurizing fluid F.

Following step S9, in step S10, the molded assembly, i.e., the intermediate body, is removed from the molding apparatus 100. Following step S10, in step S11, a plunge joint assembly is attached to the first metal member 50 of the intermediate body, and a yoke assembly is attached to the second metal member 60.

It is also possible to carry out a mandrel removal process between steps S10 and S11. This mandrel removal process involves removing the mandrel 1A from the end opening side of the second metal member 60 to the outside of the fiber-reinforced resin pipe body 20. During this process, the mandrel 1A is removed from the inside of the fiber-reinforced resin pipe body 40 by, for example, deforming, melting, decomposing, destroying, or eluting it, depending on the material used. This achieves a reduction in the weight of the power transmission shaft 2.

Furthermore, when deforming the mandrel 1A and removing it from the end opening side of the second metal member 60, a method can be used in which, for example, the hollow portion of the mandrel body 10 is depressurized to shrink the mandrel 1A so that it is smaller than the end opening, and then the mandrel 1A can be removed from the fiber-reinforced resin pipe body 40.

When performing the mandrel removal process, the hollow portion of the mandrel body 10 can be depressurized via the communication passage 104 connected to a vacuum pump (not shown).

This mandrel removal process can be more effectively carried out by plasticizing the mandrel body 10, which is made of, for example, a thermoplastic resin, by heating or other means. It can also be effectively carried out on a mandrel body 10 made of, for example, a diamond-cut aluminum thin plate. Furthermore, when the mandrel removal process is carried out, the removed inner fitting member 20A and embedded member 30A can be reused.

A mandrel 1A according to a first embodiment of the present invention comprises a cylindrical mandrel body 10, an inner fitting member 20A fitted into the axial end of the mandrel body 10, and an embedded member 30A embedded in the axial end of the mandrel body 10, wherein the inner fitting member 20A has a flow path 20a that allows a fluid to flow into the mandrel body 10, and the hardness of the embedded member 30A is higher than the hardness of the mandrel body 10 at a temperature when heated to harden a thermosetting resin arranged on the outer surface side of the mandrel body 10.
Therefore, the mandrel 1A can prevent the leakage of the fluid (pressurizing fluid F) for increasing the pressure inside the mandrel body 10 by suppressing deformation of the end portion of the mandrel body 10.

In addition, in the mandrel 1A, the embedding member 30A has an annular shape.
Therefore, the mandrel 1A can prevent leakage of the fluid for increasing the pressure inside the mandrel body 10 by suppressing deformation of the end portion of the mandrel body 10 over the entire circumferential direction.

In the mandrel 1A, the inner fitting member 20A and the embedded member 30A are made of the same metal material.
Therefore, the mandrel 1A can prevent leakage of the fluid for increasing the pressure inside the mandrel body 10 by making the linear expansion of the inner fitting member 20A and the embedded member 30A the same.

Second Embodiment
Next, a mandrel according to a second embodiment of the present invention will be described, focusing on the differences from the mandrel 1A according to the first embodiment. As shown in Figure 10, the mandrel 1B according to the second embodiment includes an inner fitting member 20B and an embedded member 30B instead of the inner fitting member 20A and the embedded member 30A.

The other axial ends of the inner fitting member 20B and the embedded member 30B protrude axially from the small diameter portion 15 of the mandrel body 10. A male thread portion 20b is formed on the outer peripheral surface of the protruding portion of the inner fitting member 20B. The thread height of the male thread portion 20b is set radially outward from the inner peripheral surface of the small diameter portion 15. The protruding portion of the embedded member 30B extends radially inward, and a female thread portion 30b is formed on its inner peripheral surface. The inner fitting member 20B and the embedded member 30B are fixed to each other by threading the male thread portion 20b and the female thread portion 30b together. A seal member may be provided between the male thread portion 20b and the female thread portion 30b.

In the mandrel 1B according to the second embodiment of the present invention, the end of the inner fitting member 20B and the end of the embedded member 30B protrude from the mandrel body 10 and are fastened to each other by screws.
Therefore, the mandrel 1B can suitably prevent leakage of the fluid for increasing the pressure inside the mandrel body 10 by fixing the inner fitting member 20B and the embedded member 30B to each other.

Third Embodiment
Next, a mandrel according to a third embodiment of the present invention will be described, focusing on the differences from the mandrel 1A according to the first embodiment. As shown in Figure 11, the mandrel 1C according to the third embodiment includes an inner fitting member 20C and an embedded member 30C instead of the inner fitting member 20A and the embedded member 30A.

The other axial ends of the inner fitting member 20C and the embedded member 30C protrude axially from the small diameter portion 15 of the mandrel body 10. A male thread portion 20c is formed on the outer peripheral surface of the inner fitting member 20C. The thread height of the male thread portion 20c is set at the same radial position as the inner peripheral surface of the small diameter portion 15. The protruding portion of the embedded member 30C extends radially inward, and a female thread portion 30c is formed on its inner peripheral surface. The inner fitting member 20C and the embedded member 30C are fixed to each other by threading the male thread portion 20c and the female thread portion 30c together. A seal member may be provided between the male thread portion 20c and the female thread portion 30c.

In the mandrel 1C according to the third embodiment of the present invention, the end of the inner fitting member 20C and the end of the embedded member 30C protrude from the mandrel body 10 and are fastened to each other by screws.
Therefore, the mandrel 1C can suitably prevent leakage of the fluid for increasing the pressure inside the mandrel body 10 by fixing the inner fitting member 20C and the embedded member 30C to each other.

<Fourth embodiment>
Next, a mandrel according to a fourth embodiment of the present invention will be described, focusing on the differences from the mandrel 1A according to the first embodiment. As shown in Figure 12, the mandrel D according to the fourth embodiment includes an inner fitting member 20D and an embedded member 30D instead of the inner fitting member 20A and the embedded member 30A.

The inner fitting member 20D comprises a cylindrical first member 21 housed within the small diameter portion 15 and a cylindrical second member 22 protruding from the small diameter portion 15. The inner circumferential surface of the second member 22 has the same diameter as the inner circumferential surface of the first member 21. The outer circumferential surface of the second member 22 has the same diameter as the outer circumferential surface of the small diameter portion 15. The second member 22 forms a flange portion that protrudes from the mandrel body 10 and extends radially outward. An annular recess 20d is formed on the side surface of one axial end of the second member 22. The first member 21 and second member 22 are fixed to each other by fastening using bolt B. The other axial end of the embedded member 30D protrudes from the mandrel body 10 and is fitted into the recess 20d.

When assembling the inner fitting member 20D into the small diameter portion 15 of the mandrel body 10, the worker first presses the first member 21 into the small diameter portion 15. Next, the worker abuts the second member 22 against the mandrel body 10 and the first member 21, and fits the protruding portion of the embedded member 30D into the recess 20d. Next, the worker secures the second member 22 to the first member 21 using bolt B. This assembly method improves workability because the press-fitting of the first member 21 into the mandrel body 10 and the fitting of the protruding portion of the embedded member 30D into the recess 20d are performed at different times.

In the mandrel 1D according to the fourth embodiment of the present invention, the inner fitting member 20D has a flange portion that protrudes from the mandrel body 10 and extends radially outward, and the end of the embedded member 30D is fitted into a recess 20d formed in the flange portion.
Therefore, the mandrel 1D can suitably prevent leakage of the fluid for increasing the pressure inside the mandrel body 10 by fitting the embedding member 30D into the recess 20d of the inner fitting member 20D outside the mandrel body 10.

Fifth Embodiment
Next, a mandrel according to a fifth embodiment of the present invention will be described, focusing on differences from the mandrel 1A according to the first embodiment. As shown in FIG. 13 , the mandrel 1E according to the fifth embodiment includes an inner fitting member 20E and an embedded member 30E instead of the inner fitting member 20A and the embedded member 30A. In the fifth embodiment, the inner circumferential surface of the mold 100 includes a first circumferential surface portion 111 that abuts against the outer circumferential surface of the small diameter portion 15 and a first stepped surface portion 112 extending radially inward from the end of the first circumferential surface portion 111. The inner circumferential surface of the mold 100 also includes a second circumferential surface portion 113 that extends axially from the radially inner end of the first stepped surface portion 112 and a second stepped surface portion 114 that extends radially inward from the end of the second circumferential surface portion 113. In addition, the inner surface of the mold 100 has a third peripheral surface portion 115 extending in the axial direction from the radially inner end portion of the second step surface portion 114, and a third step surface portion 116 extending radially inward from the end portion of the third peripheral surface portion 115.

The other radial end of the inner fitting member 20E and the other radial end of the embedded member 30E protrude from the mandrel body 10. The protruding length of the inner fitting member 20E is greater than the protruding length of the embedded member 30E. The outer peripheral surface and axial side surface of the protruding portion of the inner fitting member 20E (more specifically, the portion that protrudes further than the embedded member 30E) abut against the second peripheral surface portion 113 and the second step surface portion 114 of the mold 100, respectively, hermetically sealing the space therebetween. The outer peripheral surface and axial side surface of the protruding portion of the embedded member 30E abut against the third peripheral surface portion 115 and the third step surface portion 116 of the mold 100, respectively, hermetically sealing the space therebetween. With this structure, even if the pressurizing fluid F leaks between the outer surface of the inner fitting member 20E and the inner surface of the mandrel body 10, the mandrel 1E can prevent the fluid from migrating between the outer surface of the mandrel body 10 and the inner surface of the mold 100.

In the mandrel 1E according to the fifth embodiment of the present invention, the end of the embedded member 30E protrudes from the mandrel body 10 and abuts against the mold 100 inside the mold 100 for placing a thermosetting resin on the outer surface side of the mandrel body 10.
Therefore, the mandrel 1E can effectively prevent leakage of the fluid used to increase the pressure inside the mandrel body 10 by having the embedded member 30E abut against the inner surface of the mold 100 outside the mandrel body 10.

Sixth Embodiment
Next, a mandrel according to a sixth embodiment of the present invention will be described, focusing on the differences from the mandrel 1A according to the first embodiment. As shown in Figure 14, the mandrel 1F according to the sixth embodiment includes an inner fitting member 20F and an O-ring 70 instead of the inner fitting member 20A.

An annular recess 20f is formed on the outer peripheral surface of the inner fitting member 20F. The outer diameter of the inner fitting member 20F is smaller than the inner diameter of the small diameter portion 15 of the mandrel body 10. The O-ring 70 is housed in the recess 20f with a portion protruding radially outward, and is interposed between the outer peripheral surface of the inner fitting member 20F (the bottom surface of the recess 20f) and the inner peripheral surface of the small diameter portion 15, forming an airtight seal between them when compressed and deformed.

The mandrel 1F according to the sixth embodiment of the present invention includes an O-ring 70, which allows for an appropriate seal between the small diameter portion 15 of the mandrel body 10 and the inner fitting member 20F without requiring high dimensional accuracy.

While the above describes embodiments of the present invention, the present invention is not limited to these embodiments and can be modified as appropriate without departing from the spirit and scope of the present invention. For example, the fluid flowing into and filling the mandrel body 10 may not only pressurize the interior of the mandrel body 10, but also heat the thermosetting resin disposed on the outer surface of the mandrel body 10 to harden it. If such a fluid is a pressurizing fluid that does not heat the mandrel body 10, the thermosetting resin is heated by a separate heat source. Furthermore, for example, in the fourth embodiment, the inner fitting member 20D may be formed by integrally molding the first member 21 and the second member 22. Furthermore, the O-ring 70 in the sixth embodiment is also applicable to the mandrels 1B to 1E of the second to fifth embodiments. Furthermore, the mandrels 1A to 1F may further include a cylindrical metal band fitted around the mandrel body 10 radially outside the inner fitting members 20A to 20E and the embedded members 30A to 30F.

Alternatively, the mandrels 1A-1F may be removed from the molded fiber-reinforced resin pipe 40 during steps S9 and S10. The mandrel body 10 may be melted and removed by the heat of the resin 44 or the molding device (mold) 100 in step S8. It is also possible to melt and remove the mandrel body 10 using other forms of energy, such as heat, electricity, or vibration. The carbon fiber layers 41-43 may be interwoven with one another, forming a so-called crimped structure. The fiber material is not limited to carbon fiber, and may be any fiber material capable of reinforcing the resin layer (e.g., glass fiber, cellulose fiber, etc.).

1A, 1B, 1C, 1D, 1E, 1F Mandrel 10 Mandrel body 20A, 20B, 20C, 20D, 20E Inner fitting member 30A, 30B, 30C, 30D, 30E, 30F Buried member

Claims (6)

a mandrel body having a cylindrical shape;
an inner fitting member fitted into an axial end of the mandrel body;
an embedding member embedded in the axial end of the mandrel body;
A method for manufacturing a fiber reinforced resin pipe using a mandrel comprising:
a disposing step of disposing a fiber layer on an outer peripheral surface of the mandrel;
an impregnation step of impregnating the fiber layer disposed on the outer circumferential surface of the mandrel with a thermosetting resin;
a curing step of filling the mandrel body with a fluid by causing the fluid to flow into the mandrel body through a flow path formed in the inner fitting member, and heating and curing the thermosetting resin;
Including,
In the hardening step, the embedding member suppresses deformation of the portion of the mandrel body where the embedding member is embedded, thereby preventing leakage of the fluid from between the inner fitting member and the mandrel body.
A method for manufacturing a fiber-reinforced resin pipe body. The embedded member has an annular shape.
The method for manufacturing the fiber-reinforced resin pipe according to claim 1. an end of the inner fitting member and an end of the embedded member protrude from the mandrel body and are fastened to each other by screws;
The method for manufacturing the fiber-reinforced resin pipe according to claim 2. The inner fitting member includes a flange portion that protrudes from the mandrel body and extends radially outward,
An end of the embedded member is inserted into a recess formed in the flange portion.
The method for manufacturing a fiber-reinforced resin pipe according to claim 1 or 2. a step of placing the mandrel on which the fiber layer is placed in a mold between the placing step and the impregnation step;
an end of the embedding member protruding from the mandrel body and coming into contact with the mold in the accommodating step;
The method for manufacturing a fiber-reinforced resin pipe according to claim 1 or 2. The inner fitting member and the embedded member are formed of the same metal material.
The method for manufacturing the fiber-reinforced resin pipe according to any one of claims 1 to 5.