FRP molding system and method

Abstract

An FRP molding system 100 produces a hollow cylindrical FRP component 3 by applying pressure in the radial direction to a seamless hollow cylindrical preform 2 composed of an FRP material 1. The FRP molding system 100 comprises a pair of inner dies 10, a pair of outer dies 20, an outer die moving device 30, an inner die moving device 40, an auxiliary moving device 48, and a workpiece turning device 50. The outer die moving device 30 moves the outer dies 20 between a contact position F and an opening position R. The inner die moving device 40 moves the inner dies 10 between a pressing position P and a return position Q. The auxiliary moving device 48 moves the inner die moving device 40 in the Z direction. The workpiece turning device 50 turns a workpiece W in the circumferential direction thereof.

Description

FRP molding system and method

[0001] The present invention relates to a method for forming a hollow cylindrical FRP part by laminating FRP materials to form a preform.

[0002] Fiber-reinforced composite materials, such as carbon fiber reinforced plastics (CFRP), have lower densities than metal materials such as iron and aluminum, yet offer excellent mechanical properties, high specific strength, and are lightweight yet strong. For this reason, they have recently been used in aircraft, small boats, automobiles, and other structural components as an alternative to aluminum alloys. Hereinafter, fiber-reinforced composite materials will be simply referred to as "FRP." For example, aircraft structures (fusels, hatches, wings, etc.) have traditionally been made by joining aluminum alloys together using rivets. However, joining using rivets is difficult to work with, and when applied to fiber-reinforced composite materials, the internal fibers are severed, resulting in a significant decrease in tensile strength.

[0003] In order to solve this problem, the inventors of the present invention have devised a means for uniformly molding the entire arc-shaped preform by applying pressure to the arc in the radial direction (Patent Document 1).

[0004] The FRP molding system in Patent Document 1 includes upper and lower dies that clamp a portion of an arc-shaped preform in a radial direction perpendicular to the arc, a partial press device, and a conveying device. The partial press device intermittently compresses a portion of the preform to partially mold an FRP part. The conveying device intermittently moves over the compressed portion (molded portion) of the preform compressed by the partial press device.

[0005] International Publication No. 2022 / 044324

[0006] By using the method disclosed in the above-mentioned Patent Document 1, an arc-shaped FRP part (for example, a large FRP part) can be molded uniformly throughout without using a large or complicated mold.

[0007] However, while the method disclosed in Patent Document 1 can produce arc-shaped FRP parts, when the perimeter of the preform becomes longer and approaches a closed hollow cylindrical shape, it interferes with the press (partial pressing device) and cannot be molded, posing the problem of not being able to produce seamless hollow cylindrical FRP parts.

[0008] The present invention was devised to solve these problems, and its object is to provide a means by which a hollow cylindrical preform can be pressed in the radial direction against a circular arc to form a seamless hollow cylindrical FRP part.

[0009] According to the present invention, there is provided an FRP molding system for manufacturing a hollow cylindrical FRP part by radially pressurizing a seamless hollow cylindrical preform made of an FRP material, the system comprising: a pair of internal molds having inner molding surfaces that match the inner shape of the FRP part; a pair of external molds having outer molding surfaces that match the outer shape of the FRP part; an external mold moving device that moves the external molds between a contact position where the outer molding surfaces come into contact with the outer surface of a workpiece that is the preform or the FRP part, and an opening position away from the outer surface; an internal mold moving device that moves the internal molds between a pressing position where the inner molding surfaces press the inner surface of the workpiece and a return position away from the inner surface; an auxiliary moving device that moves the internal mold moving device in the Z direction which is the movement direction of the external mold; and a workpiece rotating device that rotates the workpiece in the circumferential direction; a mold positioning step that positions the external molds and the internal molds; and a partial molding step that presses and molds a portion of the workpiece between the external molds and the internal molds. The present invention provides an FRP molding system that includes a mold releasing step of releasing the inner mold and the outer mold from the workpiece, and a workpiece rotating step of rotating the workpiece in a circumferential direction, and that sequentially repeats the mold positioning step, the partial molding step, the mold releasing step, and the workpiece rotating step to mold the entire preform into the seamless hollow cylindrical FRP part.

[0010] Furthermore, according to the present invention, there is provided an FRP molding method for manufacturing the FRP part using the above-mentioned FRP molding system, wherein in the mold positioning step, the outer mold is positioned at the contact position and the inner mold is positioned at the return position; in the partial molding step, the inner mold is moved to the pressing position and a portion of the workpiece is pressed and molded between the outer mold and the inner mold; in the mold releasing step, the inner mold is returned to the return position and the outer mold is moved to the open position and the inner mold and the outer mold are released from the workpiece; in the workpiece rotating step, the workpiece is rotated by a predetermined angle in the circumferential direction; and the mold positioning step, the partial molding step, the mold releasing step, and the workpiece rotating step are repeated in order to mold the entire preform into the seamless hollow cylindrical FRP part.

[0011] According to the present invention, a pair of inner molds have inner molding surfaces that match the inner shape of the FRP part, and a pair of outer molds have outer molding surfaces that match the outer shape of the FRP part. The outer molds are moved to a contact position where the outer molding surfaces contact the outer surface of the workpiece by an outer mold moving device, and the inner mold moving device is returned to a position at the center of the workpiece by an auxiliary moving device. At this position, the inner molds are moved from the return position to a pressing position by an inner plate driving device, thereby pressing and molding a portion of the preform between the inner and outer molds.

[0012] The workpiece can be released from the inner and outer dies by returning the inner die to a return position away from the inner surface of the workpiece using the inner plate drive device and moving the outer die to an open position away from the outer surface of the workpiece using the outer die moving device. At this position, the workpiece can be rotated in the circumferential direction using the workpiece rotating device, and the unmolded portions of the preform can be positioned between the dies in order.

[0013] Therefore, by repeating the mold positioning step, partial molding step, mold release step, and workpiece rotation step in order, the entire preform can be molded into a seamless hollow cylindrical FRP part.

[0014] 9 is an overall flow diagram of the FRP manufacturing process from FRP material to the production of an FRP part. FIG. 10 is a schematic diagram of a workpiece. FIG. 11 is an explanatory diagram of an internal mold. FIG. 12 is an explanatory diagram of an external mold. FIG. 13 is an explanatory diagram of the structure of the mold. FIG. 14 is an explanatory diagram of the function of the solidification section mold. FIG. 15 is an explanatory diagram of a workpiece rotating device. FIG. 16 is an explanatory diagram of a transport device. FIG. 17 is an overall flow diagram of the FRP molding method of the present invention. FIG. 18 is an explanatory diagram of opening (step S1). FIG. 19 is an explanatory diagram of detaching the front moving device (step S2). FIG. 19 is an explanatory diagram of setting the preform (step S3). FIG. 20 is an explanatory diagram of attaching the front moving device (step S4). FIG. 21 is an explanatory diagram of mold positioning (step S5). FIG. 22 is an explanatory diagram of partial molding (step S6). FIG. 23 is an explanatory diagram of mold release (step S7). FIG. 24 is an explanatory diagram of workpiece rotating (step S8). FIG. 25 is an explanatory diagram of the case where three moldings (step S6) are repeated. FIG. 26 is an explanatory diagram of a method of repeating partial molding. FIG. 27 is an explanatory diagram of removal (step S9) of FIG. 28 is a modified example in which the axis of the workpiece is horizontal and the direction of movement of the mold is also horizontal. 10 is a modified example in which the axis of the workpiece is in the vertical direction and the moving direction of the die is in the horizontal direction. FIG. 11 is a modified example showing an example in which a press device is not used. FIG. 12 is an explanatory diagram of another variation of the present invention.

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that common parts in the drawings are given the same reference numerals and redundant explanations will be omitted.

[0016] (FRP Manufacturing Process) Figure 1 is a flow diagram of the overall FRP manufacturing process from manufacturing an FRP material 1 to manufacturing an FRP part 3. In this figure, the FRP material 1 is a sheet-like material containing a thermoplastic resin and reinforcing fibers, and is made of a single layer of prepreg or a stack of multiple prepregs.

[0017] "Prepreg" is an intermediate material made by impregnating a base material made of reinforcing fibers (such as glass fibers or carbon fibers) with resin. Thermoplastic resins solidify at room temperature.

[0018] 1, a preform is first manufactured by a lamination step T1 and a preforming step T2. Hereinafter, the preform will be simply referred to as a "preform."

[0019] In the lamination step T1, the FRP material 1 is laminated into a desired shape by, for example, automatic fiber placement (AFP), film winding (FW), hand layup, or the like.

[0020] In the preforming step T2, the laminated product stacked into a desired shape is heated and pressurized for a short period of time to produce a preform 2. The laminating step T1 and the preforming step T2 may be combined. The preform 2 has a shape similar to the final product, the FRP part 3, but there is a possibility that defects or gaps may exist inside and between the layers of the stacked FRP material 1.

[0021] Next, in a molding step T3, the preform 2 is molded into an FRP part 3.

[0022] The FRP molding system of the present invention is an apparatus for manufacturing a hollow cylindrical FRP part 3 by radially pressurizing a preform 2, which is a rotating body centered on an axis. The preform 2 has a seamless hollow cylindrical shape that is preformed by laminating FRP materials 1. The FRP molding method of the present invention is a method for manufacturing a hollow cylindrical FRP part 3 using this FRP molding system.

[0023] As described above, the FRP part 3 is made by radially pressing the preform 2, and this pressing reduces defects and gaps inside and between layers of the preform 2, reducing its radial thickness. However, since the amount of thickness reduction due to pressing is small, the preform 2 and the FRP part 3 essentially have the same shape. Hereinafter, the preform 2 and the FRP part 3 will be referred to as the "workpiece W" unless a distinction is necessary. The central axis of the workpiece W will be referred to as the "workpiece central axis C1."

[0024] 2 is a schematic diagram of the workpiece W (preform 2 and FRP part 3). In this figure, (A) and (B) are hollow barrel-shaped workpieces W, and (C) is a hollow cylindrical workpiece W.

[0025] The workpiece W is a seamless hollow cylindrical part and a rotating body with the workpiece central axis C1 as its center. The inner diameter or outer diameter of the workpiece W may vary along the workpiece central axis C1. Hereinafter, the total length of the workpiece W is defined as L, and the minimum inner diameter is defined as d.ｍｉｎ , the maximum outer diameter is D ｍａｘ Let's say.

[0026] Furthermore, parts such as stringers (not shown) may be fixed to the inner or outer surface of the above-described workpiece W. In this case, the fixed parts (such as stringers) are also referred to as the workpiece W in the present invention.

[0027] The size of the workpiece W is, for example, D ｍａｘ is 1 to 10 m, and the total length L is 1 to 10 m.

[0028] The FRP molding system of the present invention comprises a pair of inner dies 10 and a pair of outer dies 20 .

[0029] (Inner Mold 10) Fig. 3 is an explanatory diagram of the inner mold 10, in which (A) is a perspective view, (B) is a side view seen from the axial direction, and (C) is a cross-sectional view seen from the side.

[0030] In this example, the FRP molding system 100 of the present invention includes a pair of internal molds 10. Hereinafter, in this example, when necessary, the upper internal mold 10 in the drawings will be referred to as a first internal mold 10A, and the lower internal mold 10 will be referred to as a second internal mold 10B.

[0031] The pair of inner dies 10 have the same structure and can be inserted into the inside of the workpiece W. The inner dies 10 also have an inner molding surface 11 that matches the inner shape of the FRP part 3.

[0032] 3A, the pair of inner molds 10 are positioned symmetrically with respect to an imaginary mid-plane 15. The imaginary mid-plane 15 is a plane (a horizontal plane in the drawing) passing through an imaginary central axis C2, which will be described later in this example.

[0033] (Outer die 20) Fig. 4 is an explanatory diagram of the outer die 20, in which (A) is a perspective view, (B) is a side view, and (C) is a front view seen from the axial direction of the workpiece W.

[0034] In this example, the FRP molding system 100 includes a pair of external molds 20. Hereinafter, in this example, the upper external mold 20 in the drawing will be referred to as a first external mold 20A, and the lower external mold 20 will be referred to as a second external mold 20B, where necessary.

[0035] The pair of outer dies 20 are positioned outside the workpiece W and have the same structure. The outer dies 20 also have an outer molding surface 21 that matches the outer shape of the FRP part 3. Hereinafter, the inner die 10 and the outer die 20 will be simply referred to as "dies" unless it is necessary to distinguish between them.

[0036] The FRP molding system of the present invention further includes an external mold moving device 30 and an internal mold moving device 40 .

[0037] The external mold moving device 30 moves one or both of the external molds 20 between a "contact position F" where the outer molding surface 21 of the external mold 20 contacts the outer surface of the workpiece W, and an "opening position R" where the outer molding surface 21 is separated from the outer surface of the workpiece W. Hereinafter, the movement direction of the external mold 20 will be referred to as the "Z direction."

[0038] 4(C), the pair of inner dies 10 and the pair of outer dies 20 are positioned in the diametrical direction of the Z direction passing through the workpiece central axis C1. The pair of inner dies 10 are positioned between the pair of outer dies 20, facing the outer dies 20, respectively.

[0039] In FIG. 4, the external mold moving device 30 has a first external plate 32A, a second external plate 32B, and an external plate positioning device 34.

[0040] In this example, the second external plate 32B is fixed in a fixed position, and the first external plate 32A is positioned parallel to and facing the second external plate 32B, and the distance between the first external plate 32A and the second external plate 32B can be variably adjusted while maintaining its posture.

[0041] In this example, the movement direction (Z direction) of the external mold 20 is the vertical direction (top-bottom direction), which is the radial direction of the workpiece W when the workpiece W is formed. In this example, the external plate positioning device 34 moves the first external plate 32A in the Z direction and positions it.

[0042] The external plate positioning device 34 is, for example, a press device that has a bolster and a slide and molds an object between a lower mold and an upper mold. In this case, the second external plate 32B is fixed to the upper surface of the bolster, and the first external plate 32A is fixed to the lower surface of the slide. Note that the external plate positioning device 34 is not limited to a press device, and may be any device that can move the first external plate 32A in the Z direction and position it.

[0043] In Figure 4, one of the external molds 20 (second external mold 20B) is fixed to the upper surface of the second external plate 32B, and the other of the external molds 20 (first external mold 20A) is fixed to the lower surface of the first external plate 32A opposite the second external mold 20B.

[0044] In this example, at the "contact position F" of the external die moving device 30, the lower surface of the workpiece W is positioned in close contact with the outer surface molding surface 21 (upper surface) of the second external die 20B, and the outer surface molding surface 21 (lower surface) of the first external die 20A is positioned in close contact with the upper surface of the workpiece W. The Z direction position of the first external die 20A at the contact position F is a constant position (same height) in accordance with the shape of the workpiece W. Furthermore, the "opening position R" of the external die moving device 30 is a position where the first external die 20A has moved upward from the contact position F in the figure. The Z direction position of the first external die 20A at the opening position R can be set arbitrarily in accordance with the shape of the workpiece W.

[0045] In Figure 3, the internal mold moving device 40 moves the internal mold 10 between a "pressing position P" where the inner molding surface 11 of the internal mold 10 presses the inner surface of the workpiece W and a "return position Q" where the internal mold 10 is away from the inner surface of the workpiece W.

[0046] The inner mold moving device 40 includes a center plate 42 , a pair of inner plates 44 , and an inner plate driving device 46 .

[0047] In this figure, a plane that passes through the center of the pair of inner molds 10 in the Z direction and is perpendicular to the Z direction is called the "imaginary midpoint 15." The center plate 42 includes the imaginary midpoint 15 and can be inserted inside the workpiece W, with both ends positioned axially outside the workpiece W when the workpiece W is molded. Hereinafter, the central axis of the center plate 42 that includes the imaginary midpoint 15 will be called the "imaginary central axis C2."

[0048] In this example, a connecting portion 42a is provided at the front end of the center plate 42, and a cantilever support portion 42b is provided at the rear end. The connecting portion 42a is a portion that connects to a front movement device 48A, which will be described later. The connecting portion 42a is configured to be detachable from the front movement device 48A. The cantilever support portion 42b is a portion that connects to a rear movement device 48B, which will be described later. The cantilever support portion 42b is fixed to the rear movement device 48B, and is configured to be able to cantilever support the center plate 42.

[0049] The pair of internal plates 44 are located on the outside of the center plate 42, inside the workpiece W, symmetrically with respect to the imaginary midpoint plane 15, and the pair of internal dies 10 are fixed to the outer surfaces of the internal plates 44. The internal plate drive device 46 is, for example, a hydraulic ram, and moves the internal plates 44 outward in the Z direction (outward in the radial direction of the workpiece W) relative to the center plate 42.

[0050] When the internal plate driving device 46 moves the internal plate 44 outward in the radial direction of the workpiece W, the pair of internal dies 10 expand outward in the Z direction to reach the "expanded diameter position." Conversely, when the internal plate driving device 46 moves the internal plate 44 inward in the radial direction of the workpiece W, the pair of internal dies 10 contract inward in the Z direction to reach the "reduced diameter position." The pair of internal dies 10 in the reduced diameter position are spaced apart from the minimum inner diameter d of the workpiece W. ｍｉｎ The pair of inner dies 10 in the expanded diameter position are set to be larger than the maximum inner diameter of the workpiece W, and are set to come into contact with the inner surface of the workpiece W and apply pressure outward.

[0051] In this example, the "pressing position P" of the internal die moving device 40 is a position where the inner molding surfaces 11 of the pair of internal dies 10 come into close contact with and press against the inner surface of the workpiece W at two locations in the diameter direction of the workpiece W. The "return position Q" of the internal die moving device 40 is a position where the pair of internal dies 10 have contracted in diameter from the "pressing position P" and the inner molding surfaces 11 of the pair of internal dies 10 are separated from the inner surface of the workpiece W at one or both locations in the diameter direction of the workpiece W.

[0052] At the "return position Q," the virtual center axis C2 can move between a position (concentric position) that coincides with the workpiece center axis C1 and a position (offset position) that is offset from the workpiece center axis C1 within the range of the gap with the inner molding surface 11.

[0053] Hereinafter, the entire equipment including the pair of inner molds 10, the center plate 42, the inner plate 44, and the inner plate drive device 46 will be referred to as the "inner mold set IS." In addition, the position in which the inner plate drive device 46 (e.g., a hydraulic ram) is contracted will be referred to as the "reduced diameter position," and the position in which the inner plate drive device 46 is expanded will be referred to as the "expanded diameter position," and the respective states of the inner mold set IS will be referred to as the "reduced diameter state" and the "expanded diameter state."

[0054] 4, the FRP molding system 100 further includes an auxiliary movement device 48. The auxiliary movement device 48 moves the internal mold movement device 40 from the return position Q described above in the radial direction of the workpiece W. The auxiliary movement device 48 directly moves the center plate 42 in the Z direction. During molding, the "radial direction of the workpiece W" is the Z direction, which in this example is the up-and-down direction.

[0055] In this example, the auxiliary movement device 48 is fixed to the front and rear ends of the first external plate 32A and moves the center plate 42 in the movement direction (Z direction) of the first external plate 32A. The position of the "front end" is in the axial direction of the workpiece W and is the side where the workpiece W is loaded or unloaded. The position of the "rear end" is in the axial direction of the workpiece W and is the opposite side to the front end.

[0056] In this figure, the auxiliary movement device 48 has a pair of front movement devices 48A and a pair of rear movement devices 48B.

[0057] The pair of front movement devices 48A are fixed to the front end of the first external plate 32A and are configured to be able to move the front end of the center plate 42 in the Z direction. The pair of rear movement devices 48B are fixed to the rear end of the first external plate 32A and are configured to be able to move the rear end of the center plate 42 in the Z direction. The front movement devices 48A and the rear movement devices 48B move in synchronization, and raise and lower the center plate 42 while always keeping it horizontal in this example.

[0058] The front moving device 48A is further configured to be able to release the connecting portion 42a of the center plate 42 and retract the front moving device 48A to a position where it does not interfere with the workpiece W during forming. In this example, the retraction direction of the front moving device 48A is the width direction (hereinafter referred to as the Y direction) that is perpendicular to the axis of the workpiece W during forming and the Z direction.

[0059] The rear movement device 48B is also capable of cantilevering the center plate 42 via a cantilever support portion 42b fixed to the rear end portion of the first outer plate 32A.

[0060] 4, the pair of outer molds 20 are positioned opposite each other. The outer molding surface 21 of the first outer mold 20A is positioned opposite the inner molding surface 11 of the first inner mold 10A, and the outer molding surface 21 of the second outer mold 20B is positioned opposite the inner molding surface 11 of the second inner mold 10B.

[0061] 5 is an explanatory diagram of the mold structure, in which (A) is a side view of the inner mold 10 (in this example, the first inner mold 10A), (B) is a top view of the inner mold 10 (the first inner mold 10A), (C) is a cross-sectional view of the inner mold 10 and the outer mold 20 during molding, and (D) is an enlarged view of part D in (C).

[0062] 5A and 5B, the inner mold 10 is composed of a melting portion mold a and solidifying portion molds b1 and b2, which are divided in the circumferential direction. Hereinafter, the solidifying portion molds b1 and b2 will be referred to as the "solidifying portion mold b" unless it is necessary to distinguish between them.

[0063] The melting mold a is located in a forming zone ZA where the preform 2 is converted into FRP. The solidifying mold b is located in a non-forming zone ZB where the workpiece W is preheated or cooled. The non-forming zone ZB is located adjacent to and outside the forming zone ZA.

[0064] The solidification molds b are located on both circumferential sides of the melting mold a. The melting mold a and the solidification mold b are driven independently to compress the workpiece W. The melting mold a and the solidification mold b each have a heating device and a cooling device, respectively, to form a predetermined temperature distribution in the circumferential direction, as shown in FIG. 5A. In this example, the melting mold a has a temperature of 400°C, and the solidification mold b has a temperature of 200°C to 400°C, but the temperature distribution can be set arbitrarily. The solidification molds b1 and b2 may be linked or independent. A partial drive device (not shown) is also provided that can independently drive the solidification mold b or the melting mold a relative to the inner plate 44.

[0065] In Figures 5(C) and (D), both axial ends of the outer mold 20 have vertical wall portions 22 extending in the Z direction along the ends of the inner mold 10 to prevent the resin from flowing out of the molten portion mold a.

[0066] (Function of solidification mold b) Fig. 6 is a diagram illustrating the function of the solidification mold b. In this example, the thickness of the preform 2 is constant.

[0067] 6(A) shows a conventional example that does not use a solidification mold b, in which a preform 2 of a uniform thickness is held between an outer mold 20 and an inner mold 10, and the outer mold 20 and inner mold 10 are heated to heat the preform 2 between them, resulting in a molten state in which the resin melts. In this case, low-temperature zones (non-molding zones ZB) with relatively low temperatures and little expansion are generated at the circumferential ends of the outer mold 20 and inner mold 10, and a transition zone is generated between these zones and the molten zone (molding zone ZA) that melts and expands. The amount of expansion is, for example, about 3% by volume.

[0068] The transition zone has an intermediate temperature between the low-temperature zone and the molten zone, and is in a state where the viscosity of the resin begins to decrease. In this transition zone, the inner and outer molds cannot follow the volumetric changes of the preform 2 or FRP part 3, and a gap is created between the preform 2 or FRP part 3. In this state, if the low-temperature zone in the transition zone is the preform 2 or FRP part 3, the heat input releases residual stress from the previous molding, causing the layers to meander out of plane. Alternatively, microvoids present inside the resin or between the resin and the fibers expand. As a result, voids are created inside the resin, between the resin and the fibers, or both. Because the resin is not completely melted in the transition zone and load is not transmitted from the mold, the voids are not filled, resulting in internal defects.

[0069] Figure 6(B) is a schematic diagram of molding using the solidification mold b of the present invention, showing the state in which the solidification mold b is driven and pressed down independently of the outer mold 20. With this configuration, when the low-temperature portion in the transition section is the FRP part 3, the residual stress from the previous molding is not released, preventing out-of-plane meandering of the layers. Furthermore, even when the low-temperature portion is the preform 2 and the FRP part 3, pressure is applied by the solidification mold b, preventing the expansion of microvoids present inside the resin or between the resin and the fibers. In this state, as shown in Figure 5(B), a step corresponding to the thermal expansion difference occurs between the solidification mold B and the outer mold 20.

[0070] Figure 6(C) is a schematic diagram of the state after molding using the solidification mold b of the present invention, showing the state in which the mold has cooled from the state in Figure 6(B) and the preform 2 has solidified. Between Figures 6(B) and 6(C), pressure is applied by the solidification mold b and the upper and lower molds. As the temperatures of the molten and transition zones decrease, the amount of thermal expansion decreases, and the entire zone becomes a low-temperature zone, eliminating the step between the solidification mold b and the outer mold 20.

[0071] The temperature of the high-temperature end of the solidification mold b is preferably maintained at +10°C to +20°C above the melting point of the thermoplastic resin, and the temperature of the low-temperature end is preferably maintained at -20°C to -30°C above the melting point of the thermoplastic resin. This temperature gradient is preferably achieved by controlling the temperatures of the low-temperature and high-temperature sides around the solidification mold b using a heating device. Temperature measurement is preferably performed by inserting a thermocouple inside the solidification mold b.

[0072] In this case, the high-temperature side of the solidification mold b is located near the boundary between the melting part and the transition part, as shown in Figure 6(B), and the resin on the high-temperature side can be deformed by the pressure of the solidification mold b. The distance between the low-temperature side and the high-temperature side of the solidification mold b is preferably, for example, 50 mm or more. The distance between the low-temperature side and the high-temperature side depends on the temperature gradient that can be formed in the mold, i.e., the mold structure.

[0073] (Additional Functions of Solidification Mold b) In the conventional example of Figure 6(A), there is a gradient in internal pressure between the center and end portions of the outer mold 20 and inner mold 10, and the molten part has fluidity, so the preform 2 stretches from the center toward the end portions during molding. The amount of this stretching reaches, for example, about 1% or more of the molding range. In the present invention of Figures 6(B) and (C), the use of solidification mold b can suppress the above-mentioned stretching phenomenon.

[0074] (Workpiece Rotating Device 50) The FRP molding system 100 of the present invention further includes a workpiece rotating device 50. Fig. 7 is an explanatory diagram of the workpiece rotating device 50. The workpiece rotating device 50 rotates the workpiece W (preform 2 or FRP part 3) in the circumferential direction around the workpiece central axis C1.

[0075] 7A is a side view showing the positions of the inner die 10 and the outer die 20, and FIG. 7B is a diagram showing the structure of the workpiece rotating device 50 as seen from the axial direction of the workpiece W.

[0076] In FIG. 7A, the inner die 10 and the outer die 20 are spaced apart from the workpiece W, allowing the workpiece W to freely rotate around the workpiece central axis C1. In this case, the imaginary central axis C2 preferably coincides with the workpiece central axis C1, but they may differ. In FIG. 7B, the workpiece rotating device 50 has multiple (four in this example) outer rollers 52 that contact the outer surface of the workpiece W in a rotatable state. The multiple outer rollers 52 are configured to be movable in the radial direction of the workpiece W and to be rotatable around their respective axes. The axial length of the outer rollers 52 is optional, as long as they contact only a portion of the axial direction of the outer surface of the workpiece W. With this configuration, the workpiece W is supported in a position where it can freely rotate, and the rotation of the outer rollers 52 allows the workpiece W to rotate in the circumferential direction around the workpiece central axis C1.

[0077] 7(B), an internal roller 54 may be provided inside the workpiece W. The axial length of the internal roller 54 is arbitrary, and it is sufficient that the internal roller 54 faces the external roller 52 in the radial direction and contacts a portion of the axial direction of the inner surface of the workpiece W. In this case, the internal roller 54 is preferably allowed to freely rotate while in contact with the inner surface of the workpiece W, but may also be rotated in synchronization with the external roller 52.

[0078] (Transportation Device 60) The FRP molding system 100 of the present invention further includes a transport device 60. The transport device 60 transports the workpiece W between the inner mold 10 and the outer mold 20 or removes it.

[0079] 8 is an explanatory diagram of the conveying device 60. In this figure, (A) is a side view showing the positions of the inner mold 10 and the outer mold 20, (B) is a side view of the conveying device 60, and (C) is a view taken along the CC arrows in (B).

[0080] In FIG. 8A, the workpiece W is separated from the inner mold 10 and the outer mold 20. In FIGS. 8B and 8C, the conveying device 60 has multiple grippers 62 that can be inserted axially through the gap between the inner mold 10 and the outer mold 20. The multiple grippers 62 (four in this example) are spaced apart in the circumferential direction of the workpiece W. One end (the left end in the figure) of each of the multiple grippers 62 is cantilevered by multiple support parts 64, and each support part 64 is attached to a rotary table 66 so as to be movable in the radial direction. The rotary table 66 is rotatable about a rotation axis (a horizontal axis in this example) that is parallel to the workpiece central axis C1 and coincides with the width direction, and is movable in the longitudinal direction of the workpiece W. Furthermore, the rotation axis of the rotary table 66 can be positioned at a height that coincides with the workpiece central axis C1 during loading or unloading.

[0081] With the above-described configuration, the rotation axis of the rotary table 66 is aligned with the workpiece central axis C1 during loading or unloading, the rotary table 66 is moved in the axial direction of the workpiece W, and the outer surface of the workpiece W is gripped by the multiple grippers 62. This allows the workpiece W to be loaded or unloaded (loaded or unloaded) between the inner mold 10 and the outer mold 20. Furthermore, as the rotary table 66 rotates, the multiple grippers 62 rotate, allowing the workpiece W to rotate around the workpiece central axis C1. The drive source may be a servo motor, a linear motor, an air cylinder, a hydraulic cylinder, or the like.

[0082] FIG. 9 is a flow chart showing the overall process of the FRP molding method of the present invention, which is made up of steps (processes) S1 to S9.

[0083] Using the above-described FRP molding system 100, the FRP molding method of the present invention includes a workpiece carrying-in process P1, a workpiece molding process P2, and a workpiece carrying-out process P3.

[0084] The workpiece carrying-in process P1 comprises the steps of opening (S1), detaching the front moving device (S2), setting the preform (S3), and attaching the front moving device (S4).

[0085] 10A and 10B are explanatory diagrams of the opening step (step S1). In Fig. 10A, the first external plate 32A rises, and the first external mold 20A rises to the "opening position R." In addition, the auxiliary movement device 48 (the front movement device 48A and the rear movement device 48B) extends, and the inner mold set IS falls to the "set position." The set position is a position where a gap is formed between the pair of inner molds 10 and the pair of outer molds 20, allowing the workpiece W to be inserted in the axial direction.

[0086] It is preferable that the inner mold set IS descends after the first outer mold 20A ascends, but either can be done first as long as they do not interfere with each other. In Figure 10(B), the inner plate drive device 46 of the inner mold set IS is in the "return" state and is contracted. In other words, the pair of inner molds 10 has shrunk to be smaller than the internal volume of the preform 2, and the inner mold set IS is in a reduced diameter state.

[0087] 11 is an explanatory diagram of the front moving device detachment step (step S2). In FIG. 11(A), the front moving device 48A on the set side (loading / unloading side) is detached from the connecting portion 42a and opens to the left and right in the figure. In FIG. 11(B), the front moving device 48A moves left and right and is detached from the connecting portion 42a, and when it reaches the position of the connecting portion 42a, it is fixed to the center plate 42. This connecting structure is, for example, a spigot structure.

[0088] 12 is an explanatory diagram of the preform setting step (step S3). As shown in this figure, the preform 2 is set around the pair of inner molds 10. That is, with the workpiece central axis C1 coinciding with the imaginary central axis C2, the workpiece W is inserted axially outside the pair of inner molds 10 and inside the pair of outer molds 20. This insertion (carrying in) is preferably performed using the above-mentioned conveying device 60. Note that, for example, a robot hand or other equipment (such as a dolly) may also be used.

[0089] 13 is an explanatory diagram of the front movement device attachment step (step S4). In FIG. 13, the front movement device 48A on the set side (loading / unloading side) returns to the fixed position and is connected to the center plate 42 via the connecting portion 42a.

[0090] In FIG. 9, the workpiece molding process comprises the steps of die positioning (S5), partial molding (S6), die release (S7), and workpiece rotation (S8).

[0091] 14 is an explanatory diagram of the die positioning step (step S5). In the die positioning step (step S5), the outer die 20 is positioned at the contact position F, the inner die 10 is positioned at the return position Q, and the pair of inner dies 10 are positioned symmetrically with respect to a plane passing through the axis of the workpiece W.

[0092] 14, first, the front moving device 48A is retracted, and the inner die 10 (inner die set IS) is raised. Next, the first outer die 20A is lowered to a predetermined position (contact position F). At contact position F, the lower surface of the workpiece W is positioned in close contact with the outer surface molding surface 21 of the second outer die 20B, and the upper surface of the workpiece W is positioned in close contact with the outer surface molding surface 21 of the first outer die 20A. Also, at this position, the inner die set IS is in a contracted state, the pair of inner dies 10 are at return position Q, and the imaginary central axis C2 coincides with the workpiece central axis C1.

[0093] 15 is an explanatory diagram of the partial molding step (step S6). In the partial molding step (step S6), the inner die 10 is moved to the pressing position P, and a part of the workpiece W is pressed and molded between the outer die 20 and the inner die 10.

[0094] That is, in the partial molding step (step S6), the internal plate drive device 46 is extended to the "out" state, and the inner molding surface 11 of the internal mold 10 is pressed against the inner surface of the preform 2. As a result, the preform 2 is compressed between the external mold 20 and the internal mold 10. During molding, compression, heating, pressure-boosting compression, temperature maintenance, and cooling are carried out. Both the internal mold 10 and the external mold 20 are equipped with a heating device and a cooling device.

[0095] In the partial molding process (step S6), the pair of inner dies 10 and the pair of outer dies 20 are each positioned in the diametric direction passing through the workpiece central axis C1, and the workpiece W is simultaneously molded at the upper and lower parts of the workpiece W, which are symmetrically positioned with respect to the workpiece central axis C1. Therefore, the pressing forces of the pair of inner dies 10 are canceled out, so no pressing force acts on the center plate 42, and the required output of the auxiliary movement device 48 can be set small. Furthermore, the pressing force acting on the pair of outer dies 20, i.e., the pressing force required for molding, is applied by the pressing force of the pair of inner dies 10. Therefore, it is only necessary to control the position of the first outer plate 32A by the outer plate positioning device 34 so that the first outer plate 32A can maintain its position (contact position F) during molding.

[0096] Furthermore, the pressure force of the inner mold 10 acting on the first outer plate 32A during molding is significantly smaller than when the entire workpiece W is pressed simultaneously, because the molding range of the workpiece W is limited to a predetermined angular range. Also, because molding is performed simultaneously at the top and bottom of the workpiece W, which are symmetrical with respect to the workpiece central axis C1, molding time can be reduced by half compared to when molding only the top or bottom.

[0097] 16 is an explanatory diagram of the mold releasing step (step S7). In the mold releasing step (step S7), the inner mold 10 is moved to a return position Q, and the outer mold 20 is moved to an opening position R, whereby the inner mold 10 and the outer mold 20 are released from the workpiece W.

[0098] The inner mold 10 is released by the inner plate drive device 46 retracting and returning to the reduced diameter position. In this case, the inner mold set IS is in a reduced diameter state, the inner mold 10 moves inward, and the inner molding surface 11 separates from the inner surface of the workpiece W.

[0099] On the other hand, the release of the outer mold 20 involves simultaneously lifting the first outer plate 32A and extending the auxiliary movement device 48. In this case, by setting the lift amount of the first outer plate 32A to twice the extension amount ΔZ of the auxiliary movement device 48, or 2ΔZ, a gap equivalent to the extension amount ΔZ of the auxiliary movement device 48 can be formed outside the upper and lower inner molds 10 without changing the height of the center plate 42. In this state, it is preferable that the outer surface of the workpiece W is supported by the external rollers 52 of the workpiece turning device 50 and that the workpiece central axis C1 is positioned concentrically with the imaginary central axis C2. However, this configuration is not essential; the workpiece central axis C1 does not have to coincide with the imaginary central axis C2 as long as the workpiece W is spaced apart from the inner mold 10 and the outer mold 20.

[0100] FIG. 17 is an explanatory diagram of the workpiece turning step (step S8). In the workpiece turning step (step S8), the workpiece W is turned circumferentially by a predetermined angle around the workpiece central axis C1. This turning is preferably performed using the workpiece turning device 50 described above. Note that, for example, a robot hand or other equipment (such as a cart) may also be used. Furthermore, the predetermined turning angle is preferably set so that the portion of the FRP material 1 that has been converted into FRP in the immediately preceding partial molding step is included in the molded portion in the next partial molding step.

[0101] In the workpiece molding process P2 in FIG. 9, the above-mentioned steps of mold positioning (S5), partial molding (S6), mold release (S7), and workpiece rotation (S8) are repeated in order.

[0102] Figure 18 is an explanatory diagram of the case where the partial molding step (step S6) is repeated three times. The dashed-line frame in the figure indicates the molding range, and the numbers n1, n2, and n3 indicate the molding order. As shown in (A), (B), and (C) in this figure, mold positioning (S5), partial molding (S6), mold release (S7), and workpiece rotation (S8) are repeated in sequence until the entire preform 2 becomes the FRP part 3. In this example, the rotation angle of the workpiece rotation step (step S8) is approximately 60°. This rotation angle is determined by the size of the molds (inner mold 10 and outer mold 20) and is set to an angle below the angle that can be molded in one molding run.

[0103] 19 is an explanatory diagram of a partial molding repeat method. In this figure, the molding positions of the inner mold 10 and the outer mold 20 are fixed, and the molding portion of the preform 2 moves in the circumferential direction X.

[0104] In the first molding, the molding zone ZA (the shaded area in the figure) molds the preform 2 into an FRP part 3. In the second molding, the rear end (left end in the figure) of the part molded in the first molding is positioned and molded in the second molding zone ZA. With this configuration, the rear end of the part molded in the first molding is molded into the FRP part 3, and then heated and molded again, so that the rear end of the first molding and the front end of the second molding can be molded into a seamless FRP part 3. The molding process from the third molding onwards is the same as the second molding.

[0105] As described above, when the entire preform 2 is molded into the FRP part 3 by repeated partial molding, the area that was converted into FRP in the previous round is included in the molding zone ZA of the next round. Note that molding may be performed by positioning the rear end of the first round and the front end of the second round so that they come into contact with each other.

[0106] In the method of the present invention, the above-described mold positioning step, partial molding step, mold releasing step, and workpiece rotating step are repeated in order to mold the entire preform 2.

[0107] Figure 20 is an explanatory diagram of the removal step (step S9) of Figure 9. In the removal step (step S9), the front moving device 48A on the set side (loading / unloading side) disengages from the center plate 42 and opens to the left and right. In this state, the FRP part 3 is separated from the inner mold 10 and the outer mold 20, so the FRP part 3 can be removed in the axial direction. This removal (unloading) is preferably performed using the transport device 60 described above. Note that, for example, a robot hand or other equipment (such as a dolly) may also be used.

[0108] 21 to 23 are explanatory diagrams of variations of the present invention.

[0109] 21 shows a modified example in which the workpiece central axis C1 is horizontal and the movement direction (Z direction) of the molds (the inner mold 10 and the outer mold 20) is also horizontal. As in this example, the movement direction (Z direction) of the molds may be horizontal.

[0110] 22 shows a modified example in which the workpiece central axis C1 is vertical and the movement direction (Z direction) of the molds (the inner mold 10 and the outer mold 20) is horizontal. As in this example, the movement direction (Z direction) of the molds may be horizontal and the workpiece central axis C1 may be vertical (top-bottom).

[0111] As described above, the role of the outer mold 20 in the present invention is not to apply pressure, but to determine the outer surface shape of the FRP part 3. Therefore, it is important that the pair of outer molds 20 can be accurately positioned in the direction of mold movement (Z direction) while maintaining their parallelism. If this role is fulfilled, it is not necessary to use a press device to move the outer mold 20 up and down.

[0112] Figure 23 shows a modified example in which a press device is not used. Figure 23(A) shows the molding process, in which a support rod 72 and a clamp device 74 are provided to maintain the distance between the upper and lower outer plates 32A and 32B at the molding position.

[0113] The support rod 72 (stop rod) has, for example, a linear drive device (e.g., a pneumatic cylinder) built in it, and can extend and retract vertically from its maximum length to its minimum length. Furthermore, its overall length at its minimum length corresponds to the inner spacing between the upper and lower outer plates 32A, 32B at the workpiece forming position. The clamp device 74 is a rod-shaped member extending vertically from the outer end faces of the upper and lower outer plates 32A, 32B in the figure. Furthermore, the clamp device 74 is equipped at its upper end or both ends with claws 75 that extend between the inner and outer sides of the outer end faces of the upper and lower outer plates 32A, 32B, and a claw drive device (not shown) that drives the claws 75. The spacing between the upper and lower claws 75 corresponds to the spacing between the outer end faces of the upper and lower outer plates 32A, 32B at the workpiece forming position.

[0114] With this configuration, during molding, the support rod 72 at the shortest position maintains the inner spacing between the outer plates 32A, 32B at the work molding position, and the upper and lower claws 75 prevent the spacing between the outer plates 32A, 32B from widening. Therefore, in this state, the reaction force from the inner mold 10 can be received by the upper and lower claws 75 of the clamp device 74.

[0115] Furthermore, when the mold is released, the upper claws 75 of the clamping device 74 are moved outward from the outer end surfaces of the upper and lower outer plates 32A, 32B, and the support rod 72 is extended from its shortest length, thereby lifting the outer mold.

[0116] FIG. 24 is an explanatory diagram of another variation of the present invention. In this example, (A), (B), and (C) are common in that the first external panel 32A is positioned on the upper side and the second external panel 32B is positioned on the lower side. In FIG. 24(A), the lower second external panel 32B is fixed, and the upper first external panel 32A is moved or slid up and down. Also, in this example, an auxiliary movement device 48 is attached to the fixed-side second external panel 32B. In FIGS. 24(B) and (C), the upper first external panel 32A is fixed, and the lower second external panel 32B is moved or slid up and down. In FIG. 24(B), as in FIG. 24(A), the auxiliary movement device 48 is attached to the fixed-side second external panel 32B. In FIG. 24(C), the auxiliary movement device 48 is attached to the movable-side first external panel 32A.

[0117] In the embodiment shown in FIG. 4, the rear movement device 48B supports the center plate 42 in a cantilever manner using the cantilever support portion 42b, so that the front movement device 48A can be omitted.

[0118] According to the embodiment of the present invention described above, the pair of inner molds 10 have inner molding surfaces 11 that match the inner shape of the FRP component 3, and the pair of outer molds 20 have outer molding surfaces 21 that match the outer shape of the FRP component 3. Furthermore, the outer mold moving device 30 can move the outer mold 20 to a contact position F where the outer molding surface 21 contacts the outer surface of the workpiece W, and the auxiliary moving device 48 can position the inner mold moving device 40 at a return position Q to the center of the workpiece W. At this position, the inner mold 10 can be moved from the return position Q to a pressing position P by the inner plate driving device 46, thereby pressing and molding a portion of the preform 2 between the inner mold 10 and the outer mold 20.

[0119] Furthermore, the workpiece W can be released from the inner mold 10 and the outer mold 20 by returning the inner mold 10 to the return position Q using the inner plate driving device 46 and moving the outer mold 20 to the opening position R using the outer mold moving device 30. At this position, the workpiece W can be rotated in the circumferential direction using the workpiece rotating device 50, and the unmolded portions of the preform 2 can be positioned between the molds in order.

[0120] Therefore, by repeating the mold positioning step, partial molding step, mold release step, and workpiece rotation step in order, the entire preform can be molded into a seamless hollow cylindrical FRP part 3.

[0121] Furthermore, in the present invention, since the upper and lower parts of the workpiece W are simultaneously formed at symmetrical positions in the diameter direction passing through the workpiece central axis C1, the pressure forces of the pair of internal dies 10 are offset, allowing the required output of the auxiliary movement device 48 to be set small. Also, it is sufficient to control the position of the first external plate 32A so that the first external plate 32A maintains the contact position F during forming, and the pressure force acting on the first external plate 32A can be reduced because the forming range of the workpiece W is limited to a predetermined angular range. Furthermore, since the upper and lower parts of the workpiece W are simultaneously formed at symmetrical positions with respect to the workpiece central axis C1, the forming time can be reduced by half compared to forming on only one side.

[0122] The present invention also has the following features: (1) It is possible to form cylindrical parts made of thermoplastic resin FRP by press molding. (2) The outside is fixed and pressure is applied from the inside of the cylinder. (3) By providing a temperature distribution in the mold, it is possible to mold parts one by one while preventing material from leaking, allowing the mold dimensions to be reduced. (4) It is possible to solve the internal defects caused by differential resin shrinkage due to temperature differences that occur when a temperature distribution is provided.

[0123] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0124] a: melting part mold, b, b1, b2: solidifying part mold, C1: workpiece central axis, C2: virtual central axis, d: ｍｉｎ Minimum inner diameter, D ｍａｘ Maximum outer diameter, F contact position, P pressing position, Q return position, R opening position, L workpiece overall length, P1 workpiece loading process, P2 workpiece molding process, P3 workpiece unloading process, IS inner die set, W workpiece, ZA molding zone, ZB non-molding zone, 1 FRP material, 2 preform, 3 FRP part, 10 inner die, 10A first inner die, 10B second inner die, 11 inner molding surface, 15 virtual intermediate surface, 20 outer die, 20A first outer die, 20B second outer die, 21 outer molding surface, 22 standing wall portion, 30 outer die moving device, 32A first outer plate, 32B second outer plate, 34 outer plate positioning device, 40 inner die moving device, 42 center plate, 42a Connection part, 42b cantilever support part, 44 inner plate, 46 inner plate drive device, 48 auxiliary movement device, 48A front movement device, 48B rear movement device, 50 workpiece turning device, 52 outer roller, 54 inner roller, 60 conveying device, 62 gripping tool, 64 support part, 66 rotating table, 72 support rod, 74 clamping device, 75 jaw, 100 FRP molding system

Claims

1. An FRP molding system for manufacturing hollow cylindrical FRP parts by radially pressurizing a seamless hollow cylindrical preform made of FRP material, comprising: a pair of internal molds having inner molding surfaces that match the inner shape of the FRP part; a pair of external molds having outer molding surfaces that match the outer shape of the FRP part; an external mold moving device that moves the external molds between a contact position where the outer molding surfaces contact the outer surface of the workpiece, which is the preform or the FRP part, and an opening position away from the outer surface; an internal mold moving device that moves the internal molds between a pressing position where the inner molding surfaces press against the inner surface of the workpiece and a return position away from the inner surface; an auxiliary moving device that moves the internal mold moving device in the Z direction, which is the movement direction of the external molds; and a work rotating device that rotates the workpiece in the circumferential direction; and a mold positioning process that positions the external molds and the internal molds; and a partial molding process that pressurizes and molds a portion of the workpiece between the external molds and the internal molds. an FRP molding system comprising: a mold releasing step of releasing the inner mold and the outer mold from the workpiece; and a workpiece rotating step of rotating the workpiece in a circumferential direction, wherein the mold positioning step, the partial molding step, the mold releasing step, and the workpiece rotating step are repeated in order to mold the entire preform into the seamless hollow cylindrical FRP part.

2. The FRP molding system according to claim 1, wherein the external mold moving device comprises: a second external plate fixed in a fixed position; a first external plate positioned opposite and parallel to the second external plate and capable of variably adjusting the distance between it and the second external plate while maintaining its posture; and an external plate positioning device that moves the first external plate in the Z direction and positions it, one of the external molds being fixed to the upper surface of the second external plate, and the other of the external molds being fixed to the lower surface of the first external plate.

3. The FRP molding system according to claim 1, wherein the pair of internal dies and the pair of external dies are positioned in the diametrical direction of the Z direction passing through the central axis of the workpiece, and the pair of internal dies are positioned between the pair of external dies, facing the external dies, respectively.

4. The FRP molding system described in claim 2, wherein the internal mold moving device comprises: a center plate that includes an imaginary mid-plane that is a plane that passes through the centers of the pair of internal molds in the Z direction and is perpendicular to the Z direction, that can be inserted inside the workpiece, and that has both ends located axially outside the workpiece when the workpiece is molded; a pair of internal plates that are located outside the center plate inside the workpiece, symmetrically with respect to the imaginary mid-plane, and to whose outer surfaces the pair of internal molds are respectively fixed; and an internal plate drive device that moves the internal plate in the Z direction relative to the center plate.

5. The FRP molding system according to claim 4, wherein the auxiliary movement device is fixed to the first outer plate or the second outer plate and moves the central plate in the Z direction.

6. An FRP molding system as described in claim 4, wherein the center plate has a cantilever support portion at its rear end that can be cantilevered, and the auxiliary movement device has a rear movement device that can move the cantilever support portion in the Z direction.

7. An FRP molding system as described in claim 6, wherein the center plate has a connecting portion at its front end, the auxiliary moving device has a front moving device that can move the front end of the center plate in the Z direction, and the front moving device is configured to be able to release the connecting portion and retreat to a position where it does not interfere with the workpiece.

8. The FRP molding system according to claim 7, wherein the front moving device and the rear moving device move the center plate synchronously in the Z direction.

9. The FRP molding system according to claim 1, wherein the internal mold comprises a melting mold and a solidification mold divided in the circumferential direction, each of which is independently driven in the Z direction and has a heating device and a cooling device.

10. The FRP molding system according to claim 9, wherein the melting portion mold is located in a molding zone where the preform is converted into FRP, and the solidification portion mold is located in a non-molding zone located adjacent to and outside the molding zone where the workpiece is preheated or cooled.

11. The FRP molding system described in claim 1, wherein the workpiece rotating device has a plurality of external rollers that contact the outer surface of the workpiece, and the external rollers are configured to be movable in the radial direction of the workpiece and to be rotatable about their respective axes.

12. An FRP molding system as described in claim 1, comprising a transport device that transports the workpiece between the inner mold and the outer mold or transports it out of said gap, said transport device having: a plurality of gripping tools that can be inserted axially into the gap between the inner mold and the outer mold; a plurality of support parts that cantilever one end of said gripping tools; and a rotary table to which said support parts are attached so as to be movable radially, which is rotatable around a rotation axis that coincides with the central axis of the workpiece and which is movable in the longitudinal direction of the workpiece.

13. The FRP molding system according to claim 1, wherein the workpiece is a rotating body having a central axis that is preformed by laminating the FRP material.

14. An FRP molding method for manufacturing the FRP part using the FRP molding system described in claim 1, wherein in the mold positioning step, the outer mold is positioned at the contact position, the inner mold is positioned at the return position, and the pair of inner molds are positioned symmetrically on a plane passing through the axis of the workpiece; in the partial molding step, the inner mold is moved to the pressing position and a portion of the workpiece is pressed and molded between the outer mold and the inner mold; in the mold releasing step, the inner mold is returned to the return position and the outer mold is moved to the open position to release the inner mold and the outer mold from the workpiece; in the workpiece rotating step, the workpiece is rotated by a predetermined angle in the circumferential direction; and the mold positioning step, the partial molding step, the mold releasing step, and the workpiece rotating step are repeated in order to mold the entire preform into the seamless hollow cylindrical FRP part.

15. An FRP molding method as described in claim 14, wherein in the workpiece rotating step, the workpiece is rotated in a circumferential direction so that the portion of the FRP material that has been converted into FRP in the immediately preceding partial molding step is included in the molded portion in the next partial molding step.

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