METHOD FOR MANUFACTURING A TUBE BODY

Abstract

Manufacturing process for a pipe body, including: an arrangement step for arranging fibers (13a) with respect to an outer circumferential surface of a mandrel (1) having a circular cylindrical shape with constant diameter such that the orientation angle θ of the fibers (13a) with respect to the axis (X) of the mandrel (1) is dimensioned such that the fibers (13a) are wound with less than one turn with respect to the mandrel (1); a forming step for impregnating the fibers (13a) with a resin (21) on the outer circumferential surface of the mandrel (1) and then heating the resin (21) to shape the resin (21), and between the arrangement step and the forming step, a fixing step, at least of the upper end section, for fixing the fibers (13a) with respect to the outer circumferential surface of the mandrel (1) by means of a fixing element (14C, 14D, 14E, 15) consisting of a resin, wherein the arrangement step and the forming step are carried out in a state in which the axial direction of the mandrel (1) coincides with an upward-downward direction, and wherein in the forming step the mandrel (1), on which at least the upper end section of the fibers has been fixed by the fixing element (14C, 14D, 14E, 15), is arranged in a space of a forming device (2) and the resin (21) is injected in a molten state from above the upper end section into the space in order to impregnate the fibers (13a) with the resin (21).

Description

[0001] The present invention relates to a method for manufacturing a tubular body, which is used, for example, as a drive shaft of a vehicle.

[0002] Drive shafts (cardan shafts) mounted on vehicles, as shown in JP H03-265 738 A, each have a tubular body extending in the forward-reverse direction of the vehicle. The tubular body transmits power generated by a drive system and slowed by a gearbox to a final reduction gearbox. A tubular body made of fiber-reinforced plastic and manufactured using a mandrel is known as a tubular body used for such a drive shaft.

[0003] DE 10 2014 008 649 A1 describes a method for manufacturing a pressure vessel. A supporting structure, particularly in the form of a liner, is provided. The liner consists of steel or plastic materials and is designed as a hollow body with a through-opening at each of its opposite ends. A fiber material is dry-applied to the supporting structure, forming a base structure. This application is achieved by winding or braiding the supporting structure. The supporting structure is wound in axial and tangential directions such that the fiber material is subjected primarily to tensile stress. The resulting base structure is placed in a heated molding device. Subsequently, a matrix is ​​introduced between the molding device and the base structure using a resin injection process, whereby the matrix penetrates the fiber material at least partially.

[0004] German patent DE 2 016 479 A1 describes a method for manufacturing an insulating tube capable of withstanding axial and radial loads. To manufacture the insulating tube, a fiberglass material is applied to a mold. Specifically, the fiberglass material is arranged around a male mold. A female mold is then arranged around this fiberglass material. The space between the molds is emptied or evacuated. The mold is then heated, and a thermosetting resin is applied to the fiberglass material by injecting the resin into the mold at numerous points.

[0005] DE 10 2014 222 841 A1 describes a method for producing an approximately rotationally symmetrical fiber-reinforced plastic composite component with at least one axial undercut section. First, a roving is attached at one end to a winding spindle. The winding spindle is then rotated about its axis of rotation. During this process, the roving is wound onto a holding device. The fiber preform produced by winding the roving onto the holding device initially has a smaller outer diameter than the smaller inner diameter of a forming tool. After the fiber preform has been inserted, the tool and the fiber preform, together with the winding spindle, are rotated about the axis of rotation of the winding spindle. The holding device is compressed axially, thus releasing the tension on the wound roving. Under the influence of centrifugal force, the fiber preform is deposited onto the inner surface of the tool.Before being inserted into the tool, the fiber preform is sprayed or injected with a curing liquid plastic or resin, or immersed in a resin bath. The impregnated fiber preform is then cured by heating the tool, during which time the impregnated fiber preform and the tool are rotated.

[0006] Known methods for winding a material around a mandrel include the thread winding method, which involves winding a continuous fiber impregnated with a resin, and the film winding method, which involves winding a prepreg (a film produced by impregnating a fiber material with a resin). The thread winding method is advantageous for cost-effective manufacturing but has a problem aligning the fiber material along the axis of the mandrel, or in other words, aligning the fiber material along the axis of the tube body. On the other hand, the film winding method allows for the alignment of the fiber material along the axis of the mandrel but has disadvantages in terms of manufacturing costs.

[0007] Assuming that L in this case represents the axial direction length over which fibers are arranged over a mandrel, then r represents the radius of the outer circumferential surface of the mandrel, and θ represents the orientation angle of the fibers with respect to the mandrel (see Fig. 1) If the orientation angle θ is so small that tan θ < |2πr / L|, then the fiber cannot be wound around the mandrel with one or more turns, in which case gravity may cause the fibers to separate from the mandrel.

[0008] The present invention is intended to solve such a problem, and an object of the present invention is to provide a manufacturing method for a tube body which makes it possible to reduce the displacement of a fiber body while simultaneously reducing the manufacturing costs, even when the orientation angle of the fiber body is small. Means to solve the problems

[0009] To solve the problems described above, a tube body manufacturing process comprises the following: an arrangement step for arranging fibers (hereinafter also referred to as "fiber body") with respect to an outer circumferential surface of a mandrel with a circular cylindrical shape and constant diameter such that the orientation angle θ of the fibers with respect to the axis of the mandrel is dimensioned such that the fibers are wound with less than one turn with respect to the mandrel;a forming step for impregnating the fibers with a resin on the outer circumferential surface of the mandrel and subsequently heating the resin to shape the resin, and a fixing step between the arrangement step and the forming step for fixing the fibers with respect to the outer circumferential surface of the mandrel by a fixing element consisting of a resin, wherein the arrangement step and the forming step are carried out in a state in which the axial direction of the mandrel coincides with an upward-downward direction, and wherein in the forming step the mandrel, on which at least the upper end section of the fibers has been fixed by the fixing element, is arranged in a chamber of a forming device and the resin is injected in a molten state from above the upper end section into the chamber to impregnate the fibers with the resin.

[0010] The present invention makes it possible to reduce the displacement of fibers, even when the orientation angle of the fiber body is small, while simultaneously reducing manufacturing costs. Fig. Figure 1 shows a diagram schematically illustrating a pipe body intermediate piece according to an exemplary embodiment which is not within the scope of the present invention. Fig. Figure 2 shows a diagram that schematically illustrates a mandrel according to the exemplary embodiment and a first carbon fiber layer of the tube body intermediate piece according to the exemplary embodiment. Fig. Figure 3 shows a diagram schematically illustrating a second carbon fiber layer of the tube body intermediate piece according to the exemplary embodiment. Fig. Figure 4 shows a diagram that schematically illustrates a forming device for manufacturing the tube body according to the exemplary embodiment. Fig. Figure 5 shows a diagram that schematically illustrates a pipe body produced using the pipe body intermediate piece according to the exemplary embodiment. Fig. Figure 6 shows a flowchart illustrating a pipe body manufacturing process according to the exemplary embodiment. Fig. Figure 7 shows a diagram that schematically illustrates an example of the pipe body according to the exemplary embodiment. Fig. Figure 8 shows a diagram that schematically illustrates a pipe body intermediate piece according to a first embodiment of the present invention. Fig. Figure 9 shows a flowchart illustrating a pipe body manufacturing process according to the first embodiment of the present invention. Fig. Figure 10A shows a diagram schematically illustrating a pipe body intermediate piece according to a second embodiment of the present invention. Fig. Figure 10B shows a diagram that schematically illustrates a fixing element of the pipe body intermediate piece. Fig. Figure 11 shows a diagram that schematically illustrates a tube body produced using the tube body intermediate piece according to the second embodiment of the present invention. Fig. Figure 12 shows a flowchart illustrating a pipe body manufacturing process according to the second embodiment of the present invention. Fig. Figure 13A shows a diagram schematically illustrating a pipe body intermediate piece according to a third embodiment of the present invention. Fig. Figure 13B shows a diagram that schematically illustrates a fixing element of the pipe body intermediate piece. Fig. Figure 14 shows a diagram schematically illustrating a pipe body intermediate piece according to a fourth embodiment of the present invention. Types of embodiments of the invention

[0011] One embodiment of the present invention is described in detail with reference to the drawings, assuming an exemplary case for the manufacture of a vehicle drive shaft (cardan shaft) as a tubular body using a carbon fiber reinforced plastic. In the following descriptions, identical elements are designated with the same reference numerals, and overlapping descriptions are omitted. The drawings referenced in the description are shown in a modified form for easier understanding, so that the dimensions of the parts (e.g., in Fig. 4 and Fig. The form shown in 7, or similar, of the connecting pieces 22 and 23, are not accurately depicted. <Beispielhafte Ausführungsform>

[0012] The in Fig. The pipe body intermediate piece 10A shown in Figure 1 is formed by arranging carbon fiber layers on the outer circumferential surface of a mandrel 1 (see Figure 1). Fig. 2).

[0013] As in Fig. As illustrated in Figure 2, the mandrel 1 is a metal part with a circular cylindrical tube shape. In the exemplary embodiment, which is not within the scope of the present invention, the mandrel 1 is used in a position such that the axial direction of the mandrel 1 coincides with the upward-downward direction (so-called vertical placement) until a tube body 20A (see Figure 2) is formed. Fig. 5) was manufactured via the pipe body intermediate piece 10A. <Rohrkörper-Zwischenstück>

[0014] As in Fig. As illustrated in Figure 1, the pipe body intermediate piece 10A according to the exemplary embodiment is a circular cylindrical pipe element having a plurality of stacked carbon fiber layers and which is located in the middle of the manufacture of a pipe body 20A described below (see Figure 1). Fig. 5) is formed. The pipe body intermediate piece 10A has, in sequence from the radial inside (from the side of the mandrel 1), a first carbon fiber layer 11 (see Fig. 2), a second carbon fiber layer 12 (see Fig. 3) and a third carbon fiber layer 13. It should be noted that the Fig. Figures 1 to 3 only partially illustrate the carbon fiber layers 11, 12 and 13. <<Erste Kohlefaserschicht> >

[0015] As in Fig. As illustrated in Figure 2, the first carbon fiber layer 11 is formed by a plurality of carbon fibers 11a arranged with respect to the outer circumferential surface of the mandrel 1 such that they cover the mandrel 1. The carbon fibers 11a of the first carbon fiber layer 11 are arranged such that they are wound with one or more turns at an angle of 45° to the axis of the mandrel 1 and that they run helically with respect to the axis of the mandrel 1. In other words, the orientation angle θ of the carbon fibers 11a is 45° with respect to the axis X of the mandrel 1. <<Zweite Kohlefaserschicht> >

[0016] As in Fig. As illustrated in Figure 3, the second carbon fiber layer 12 is arranged on the radially outer side of the first carbon fiber layer 11 and is formed by a plurality of carbon fibers 12a arranged to cover the first carbon fiber layer 11. The carbon fibers 12a of the second carbon fiber layer 12 are arranged such that they are wound with one or more turns at an angle of -45° to the axis of the mandrel 1 and that the carbon fibers 12a run helically with respect to the axis of the mandrel 1. In other words, the orientation angle θ of the carbon fibers 12a is -45° with respect to the axis X of the mandrel 1. <<Dritte Kohlefaserschicht> >

[0017] As in Fig. As illustrated in Figure 1, the third carbon fiber layer 13 is arranged on the radially outer side of the second carbon fiber layer 12 and is formed by a plurality of carbon fibers 13a arranged to cover the second carbon fiber layer 12. The carbon fibers 13a of the third carbon fiber layer 13 are arranged to run parallel to the axial direction of the mandrel 1. In other words, the orientation angle θ of the carbon fibers 13a with respect to the axis X of the mandrel is 10°. The carbon fibers 13a have a length corresponding to an axial direction length L of the mandrel 1, excluding their opposite end sections, which are held by fixtures. <Herstellungsverfahren des Rohrkörpers>

[0018] The following describes a method for manufacturing a pipe body via the pipe body intermediate piece 10A according to the exemplary embodiment using the Fig. 6 flowcharts are described.

[0019] First, a connecting piece (fork stub or shaft stub) 22 (see Fig. 4) arranged at an end section in the axial direction of the mandrel 1 (step S1: installation step of the connecting piece). Subsequently, as in Fig. Figure 2 illustrates how the first carbon fiber layer 11 is formed on the outer circumferential surface of the vertically placed mandrel 1 by a device not shown (step S2: formation step of the first carbon fiber layer). The following describes how in Fig. Figure 3 illustrates how the second carbon fiber layer 12 is formed on the outer circumferential surface of the first carbon fiber layer 11 above the vertically placed mandrel 1 by a device not shown (step S3: formation step of the second carbon fiber layer). Subsequently, as in Fig. 1 shown, the third carbon fiber layer 13 on the outer circumferential surface of the second carbon fiber layer 12 above the vertically placed mandrel 1 is formed by a device not shown (step S4: formation step of the third carbon fiber layer / arrangement step).

[0020] The steps described above, from the formation step of the first carbon fiber layer to the formation step of the third carbon fiber layer, can be described as a manufacturing process for a tube body intermediate piece designed to produce the tube body intermediate piece 10A.

[0021] The following will be described as in Fig. Figure 4 illustrates that the first carbon fiber layer 11, the second carbon fiber layer 12, and the third carbon fiber layer 13 above the vertically positioned mandrel 1 are impregnated with a resin 21 by a mold 2. Heat is then applied to the mold 2 to form the tube body 20 (step S5: molding step). The resin 21 is, for example, a thermosetting resin. In this exemplary embodiment, the mold of the mold 2 is divided into several parts. During the molding step, while heat is applied to the tube body intermediate 10A, a mold closing operation, which closes the mold of the mold 2, is followed by a mold clamping operation, which applies pressure to the closed mold to increase the pressure in the mold, thereby facilitating the curing of the resin 21.It should be noted that, since the description of the exemplary embodiment uses a mold with a plurality of parts, the mold closing and clamping processes are described as having been carried out. However, the clamping process is not strictly necessary. Furthermore, such a mold closing and clamping process is not strictly necessary if the mold is not divided into a plurality of parts. In the example in... Fig. In the example shown in Figure 4, the connecting piece (fork stub or shaft stub) 22 is arranged at one end section in the axial direction of the mandrel 1, and the pipe body intermediate piece 10A extends to an outer circumferential surface of the connecting piece 22. Furthermore, in the molding device 2, an intermediate space (resin reservoir 2b) is formed on the outlet side of a sprue 2a, through which the resin 21 is to be injected in a molten state. The resin 21 injected into the molding device 2 moves via the resin reservoir 2b in the axial direction of the mandrel 1. The resin 21 penetrates the first carbon fiber layer 11, the second carbon fiber layer 12, and the third carbon fiber layer 13, as described above. In a state in which the resin 21 has penetrated the carbon fiber layers 11 to 13, heat is applied to the molding device 2 and pressure is applied inside the molding device 2 to form the tube body 20A.In the exemplary embodiment, at least during the time in which the steps from step S4 to step S5 are carried out, the mandrel 1 is held in a state in which the axial direction of the mandrel 1 coincides with the upward-downward direction.

[0022] The formed tube body 20A and the mandrel 1 are then removed from the forming device 2, and the mandrel 1 is subsequently pulled out of the tube body 20A (step S6: core removal step). Following this, a connecting piece (the other fork stub or shaft stub) 23 is attached (see Fig. 7) attached to the other end section in the axial direction (lower end section) of the mandrel 1 (step S7: attachment step of the connecting piece).

[0023] The manufacturing process of the tube body according to the exemplary embodiment comprises the following: an arrangement step for arranging the fiber body (carbon fibers 13a) with respect to the outer circumferential surface of the mandrel 1 such that the fiber body extends in the axial direction of the mandrel 1; and a forming step for impregnating the fiber body with a resin 21 on the outer circumferential surface of the mandrel 1 and subsequently heating the resin 21 to shape the resin 21, wherein the arrangement step and the forming step are carried out in a state in which the axial direction of the mandrel 1 coincides with an upward-downward direction.

[0024] This design makes it possible to reduce displacement of the fiber body while simultaneously reducing manufacturing costs, even if the orientation angle θ of the fiber body is small, since the fiber body is arranged in such a way that it is difficult for the fiber body to separate from the mandrel 1 due to gravity.

[0025] Furthermore, according to the manufacturing process of the tube body, the fiber body is arranged in the arrangement step along the axial direction of the mandrel 1.

[0026] This design makes it possible to reduce displacement of the fiber body while simultaneously reducing manufacturing costs, even if the orientation angle θ of the fiber body is small, since the fiber body is arranged in a direction along the direction of gravity. <Erste Ausführungsform>

[0027] Below, a pipe body intermediate piece and a manufacturing process for a pipe body according to a first embodiment of the present invention are described, with a focus on differences from the exemplary embodiment.

[0028] As in Fig. As illustrated in Figure 8, a tube body intermediate piece 10B according to the first embodiment of the present invention has a fixing element of the upper end section 15 as an element for fixing the third carbon fiber layer 13. <<Fixierelement des oberen Endabschnitts> >

[0029] The fixing element of the upper end section 15 is an element for fixing an end section (upper end section) of the third carbon fiber layer 13 to the outer circumferential surface of an end section in the axial direction (upper end section) of the mandrel 1.

[0030] The fixing element of the upper end section 15 is a band-like elastic resin element with an adhesive part on one surface side (on the radially inner surface side).

[0031] The fixing element of the upper end section 15 is wound in a ring shape.

[0032] The fixing element of the upper end section 15 can be made of the same material as the resin 21 or can be made of a material that melts due to the respective heat of a mold (mold) 2 and / or the resin 21 in order to mix with the resin 21. <Herstellungsverfahren des Rohrkörpers>

[0033] The following describes a method for manufacturing a pipe body 20 via the pipe body intermediate piece 10B according to the first embodiment using the Fig. 9 illustrated flowcharts are described.

[0034] Between the formation step of the second carbon fiber layer and the forming step, the fixing element of the upper end section 15 is arranged on the outer circumferential surface of the upper end section of the third carbon fiber layer 13 by a device not shown, so that the upper end section of the third carbon fiber layer 13 is fixed with respect to the vertically placed mandrel 1 (step S4B, fixing step).

[0035] The manufacturing process of the tube body according to the first embodiment of the present invention includes, between the arrangement step and the forming step, the fixing step for fixing the upper end section of the fiber body with respect to the outer circumferential surface of the mandrel 1 by the fixing element of the upper end section 15.

[0036] This design makes it possible to appropriately reduce displacement of the fiber body while simultaneously reducing manufacturing costs, even if the orientation angle θ of the fiber body is small. <Zweite Ausführungsform>

[0037] Below, a pipe body intermediate piece and a manufacturing method for a pipe body according to a second embodiment of the present invention are described, with a focus on differences from the exemplary embodiment. <Rohrkörper-Zwischenstück>

[0038] As in Fig. As illustrated in Figure 10A, a tube body intermediate piece 10C according to the second embodiment of the present invention has a fixing element 14C as an element for fixing the third carbon fiber layer 13. < <fixierelement>>

[0039] As in Fig. 10A and Fig. As illustrated in Figure 10B, the fixing element 14C is an element for fixing the third carbon fiber layer 13 to the outer circumferential surface of the mandrel 1. The fixing element 14C is an elastic resin element with a tubular shape (circular cylindrical tube shape). The fixing element 14C consists of a shrinkable element that shrinks when heat is applied. The fixing element 14C has an axial length L C the axial length L of the mandrel 1 is approximately equal to that of the mandrel. The fixing element 14C has an inner diameter r C The fixing element 14C, as described above, is fitted over the mandrel 1, on which the carbon fiber layers 11, 12, and 13 are arranged. The fixing element 14C can exhibit elasticity in the radial direction and can be fitted over the mandrel 1, on which the carbon fiber layers 11, 12, and 13 are arranged, in a radially stretched state.

[0040] The fixing element 14C, as described above, is arranged to prevent the carbon fibers 13a, which are located on the outer circumferential surface of the mandrel 1, which is positioned such that its axial direction is horizontal (i.e., those located on the outer circumferential surface of the horizontally positioned mandrel 1), from detaching from the mandrel 1. In particular, the fixing element 14C prevents displacement of the fiber body in the manufacturing structure of the tube body, even if vibration or the like occurs in an intermediate section in the axial direction of a portion of the carbon fibers 13a located on a lower section of the outer circumferential surface of the mandrel 1. <Herstellungsverfahren des Rohrkörpers>

[0041] The following describes a method for manufacturing a pipe body 20C (see Fig. 11) via the pipe body intermediate piece 10C according to the exemplary embodiment using the in Fig. 12 flowcharts are described.

[0042] Between the formation step of the second carbon fiber layer and the forming step by a device not shown, a fixing element 14C is arranged on the outer circumferential surface of the third carbon fiber layer 13, thereby fixing the third carbon fiber layer 13 with respect to the vertically placed mandrel 1 (step S4C: fixing step). As in Fig. As illustrated in Figure 11, the tube body 20C produced by such a step has the fixing element 14C, which serves as a protective layer that protects the third carbon fiber layer 13.

[0043] The manufacturing process of the tube body according to the second embodiment of the present invention includes a fixing step S4C between the arrangement step and the forming step for arranging the tubular fixing element 14C with respect to the outer circumferential surface of the mandrel 1 in order to cover the fiber body.

[0044] This design makes it possible to reduce displacement of the fiber body while simultaneously reducing manufacturing costs, even if the orientation angle θ of the fiber body is small.

[0045] The manufacturing process of the tube body according to the second embodiment of the present invention includes a shrinking step which heats the fixing element using heat from both the resin and the forming device, wherein the respective heat is generated in the forming step in order to cause the fixing element to shrink.

[0046] This design enables the formation of a protective layer to safeguard the fiber body using the fixing element 14C, which reduces the displacement of the fiber body. Furthermore, this design allows the fixing element 14C to shrink simultaneously with the forming step, resulting in a reduction of manufacturing steps compared to a case where the forming and shrinking steps are performed separately. <Dritte Ausführungsform>

[0047] Below, a pipe body intermediate piece and a manufacturing method for a pipe body according to a third embodiment of the present invention are described, with a focus on the differences to the second embodiment.

[0048] As in Fig. 13A and Fig. As illustrated in Figure 13B, a tube body intermediate piece 10D according to the third embodiment of the present invention has a fixing element 14D instead of the fixing element 14C as an element for fixing the third carbon fiber layer 13. < <fixierelement>>

[0049] The fixing element 14D is a film-like elastic resin element. The fixing element 14D consists of a shrinkable element that shrinks when heat is applied. The fixing element 14D has an axial length L. D1 The axial length L of the mandrel 1 is approximately equal to that of the mandrel. The fixing element 14D has a dimension L D2 in a direction perpendicular to the axis of the fixing element 14D. This dimension is larger than the circumference 2πr of the outer circumferential surface of the mandrel 1. This fixing element 14D, as described above, is wound with one or more turns over the mandrel 1, on which the carbon fiber layers 11, 12 and 13 are arranged. <Herstellungsverfahren des Rohrkörpers>

[0050] The following describes a method for manufacturing a pipe body 20 via the pipe body intermediate piece 10D according to the first embodiment.

[0051] In the fixing step (step S4C) the first fixing element 14 is arranged on the outer circumferential surface of the third carbon fiber layer 13 by a device not shown, thereby fixing the third carbon fiber layer 13 with respect to the mandrel 1.

[0052] In the manufacturing process of the tube body according to the third embodiment of the present invention, the tubular fixing element 14D is a foil-like element that is wound with one or more turns in the circumferential direction.

[0053] This design allows for a simple arrangement of the fixing element 14D. <Vierte Ausführungsform>

[0054] A pipe body intermediate piece and a manufacturing method for a pipe body according to a fourth embodiment of the present invention are described below, with a focus on differences from the second embodiment.

[0055] As in Fig. As illustrated in Figure 14, a tube body intermediate piece 10E according to the fourth embodiment of the present invention has a plurality of fixing elements 14E instead of the fixing element 14C as elements for fixing the third carbon fiber layer 13. < <fixierelement>>

[0056] The fixing elements 14E each represent an elastic resin element with a tubular shape (circular cylindrical tube shape). Each fixing element 14E consists of a shrinkable element that shrinks when heat is applied. The fixing elements 14E each have an axial length that is less than the axial length L of the mandrel 1. The fixing elements 14E each have an inner diameter that is approximately equal to the outer diameter r of the mandrel 1. The plurality of fixing elements 14E as described above are fitted over the mandrel 1, on which the carbon fiber layers 11, 12, and 13 are arranged, such that they are equidistant from one another. The plurality of fixing elements 14E can exhibit elasticity in the radial direction and can be fitted over the mandrel 1, on which the carbon fiber layers 11, 12, and 13 are arranged, in a radially stretched state. <Herstellungsverfahren des Rohrkörpers>

[0057] The following describes a method for manufacturing a pipe body 20 via the pipe body intermediate piece 10E according to the fourth embodiment.

[0058] In the fixing step (step S4C), a plurality of fixing elements 14E are arranged on the outer circumferential surface of the third carbon fiber layer 13 by means of a device not shown, whereby opposite end sections as well as intermediate sections are fixed in the axial direction of the third carbon fiber layer 13 with respect to the mandrel 1.

[0059] In the manufacturing process of the tube body according to the fourth embodiment of the present invention, the plurality of fixing elements 14E are arranged such that they are spaced apart from each other in the axial direction of the mandrel 1.

[0060] This design reduces the amount of material required for the fixing elements 14E, thus reducing costs.

[0061] Although certain embodiments of the present invention have been described above, it is understood that the present invention is not limited to the embodiments described above and that the embodiments of the present invention can be modified accordingly insofar as they do not deviate from the core of the invention. For example, the first carbon fiber layer 11 and the second carbon fiber layer 12 can be omitted, and the third carbon fiber layer 13 can be arranged directly on the outer surface of the mandrel 1. Furthermore, the orientation angle of the carbon fibers 13a of the third carbon fiber layer 13 is not limited to 0° (not limited to running parallel to the axial direction of the mandrel 1), but can also represent an angle such that the carbon fibers 13a are wound with fewer than one turn relative to the mandrel 1.In other words, the present invention is preferably used when the orientation angle θ of the carbon fibers 13a satisfies tan θ < |2πr / L|. Furthermore, the fiber bodies used in the tube body intermediates 10A to 10E are not limited to the carbon fibers 11a to 13a and can also consist of other materials suitable for reinforcing the tube body 20. List of reference symbols: 1 thorn 10A, 10B, 10C, 10D, 10E Pipe body intermediate piece 13a Carbon fiber (fiber body) 14C, 14D, 14E Fixing element 15 Fixing element of the upper end section 20A, 20C pipe body 21 Harz< / fixierelement> < / fixierelement> < / fixierelement>

Claims

[1] Manufacturing process of a tube body, with: an arrangement step for arranging fibers (13a) with respect to an outer circumferential surface of a mandrel (1) having a circular cylindrical shape with constant diameter such that the orientation angle θ of the fibers (13a) with respect to the axis (X) of the mandrel (1) is dimensioned such that the fibers (13a) are wound with less than one turn with respect to the mandrel (1); a forming step for impregnating the fibers (13a) with a resin (21) on the outer circumferential surface of the mandrel (1) and then heating the resin (21) to shape the resin (21), and between the arrangement step and the forming step, a fixing step, at least of the upper end section, for fixing the fibers (13a) with respect to the outer circumferential surface of the mandrel (1) by means of a fixing element (14C, 14D, 14E, 15) consisting of a resin, wherein the arrangement step and the forming step are carried out in a state in which the axial direction of the mandrel (1) coincides with an upward-downward direction, and wherein in the forming step the mandrel (1), on which at least the upper end section of the fibers has been fixed by the fixing element (14C, 14D, 14E, 15), is arranged in a space of a forming device (2) and the resin (21) is injected in a molten state from above the upper end section into the space in order to impregnate the fibers (13a) with the resin (21). [2] Manufacturing method of a tube body according to claim 1, wherein the fixing element (14C, 14D, 14E, 15) fixes only the at least upper end section (15) of the fibers. [3] Manufacturing method of a tube body according to claim 1 or 2, wherein the fixing element (14C) is tubular in shape. [4] Manufacturing method of a tube body according to claim 3, further comprising a shrinking step for heating the fixing element (14C, 14D, 14E, 15) using heat from both the resin (21) and the forming device (2), wherein the heat is generated in each of the forming steps to cause the fixing element (14C, 14D, 14E, 15) to shrink. [5] Manufacturing method of a tube body according to claim 3 or claim 4, wherein the fixing element (14D) with the tube shape is a foil-like element that is wound with one or more turns in the circumferential direction. [6] Manufacturing method of a tube body according to claim 3 or claim 4, wherein the fixing element (14E) consists of a plurality of fixing elements (14E), wherein the plurality of fixing elements (14E) are arranged in the fixing step such that they are spaced apart in the axial direction of the mandrel (1). [7] Manufacturing method of a tube body according to any one of claims 1 to 6, wherein the fixing element (14C, 14D, 14E, 15) is made of the same material as the resin (21) or is made of a material which melts through heat of the forming device (2) and / or the resin (21) in order to mix with the resin (21).

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