Manufacturing method for fiber-reinforced resin molded products

Abstract

To provide a method for manufacturing a fiber-reinforced resin molded article which can suppress occurrence of voids.SOLUTION: A method for manufacturing a fiber-reinforced resin molded article 1 obtained by impregnating a sheet-like reinforcement fiber base material 2 with a thermosetting resin 3, and thermosetting the thermosetting resin 3 includes: a decompression step of evacuating the inside a cavity C of a molding die 20 where the reinforcement fiber base material 2 is set through a vent 21C; a resin injection step S5 of injecting the thermosetting resin 3 into the decompressed cavity C, and filling the cavity C with the thermosetting resin 3; and an opening / closing repeating step of repeating opening and closing of the vent 21C during the resin injection step S5, and thereby repeatedly dwelling and decompressing the cavity C through the vent 21C.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a fiber-reinforced resin molded product. More specifically, it relates to a method for manufacturing a fiber-reinforced resin molded product obtained by impregnating a sheet-shaped reinforcing fiber base material with a thermosetting resin and thermosetting it.

Background Art

[0002] Patent Document 1 discloses a method for manufacturing a fiber-reinforced resin molded product using the RTM (Resin Transfer Molding) molding method. Specifically, in the RTM molding method, first, a sheet-shaped reinforcing fiber base material made of reinforcing fibers such as carbon fibers and glass fibers is set in the cavity of a mold.

[0003] Next, after evacuating the inside of the clamped cavity, a thermosetting resin is injected into the cavity, and while impregnating the reinforcing fiber base material with this thermosetting resin, it is filled into the cavity. Then, by heating the mold after the above filling, the thermosetting resin in the state of being impregnated into the reinforcing fiber base material is thermoset, and a fiber-reinforced resin molded product, which is a resin molded product integrated with the reinforcing fiber base material, is molded.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the configuration described in Patent Document 1, although the thermosetting resin is injected while evacuating the inside of the cavity, the air (bubbles) inside the cavity is not completely discharged, and voids are generated in the molded product. Therefore, the present invention provides a method for manufacturing a fiber-reinforced resin molded product capable of suppressing the generation of voids.

Means for Solving the Problems

[0006] As a means of solving the above problems, the method for manufacturing fiber-reinforced resin molded articles of the present invention employs the following means.

[0007] In other words, the first invention of the present invention is a method for manufacturing a fiber-reinforced resin molded product obtained by impregnating a sheet-shaped reinforcing fiber substrate with a thermosetting resin and thermosetting it, comprising: a depressurization step of vacuuming the cavity of a mold in which the reinforcing fiber substrate is set through a vent; a resin injection step of injecting and filling the depressurized cavity with the thermosetting resin; and an opening and closing repetition step of repeatedly closing and opening the vent during the resin injection step to repeatedly maintain and depressurize the cavity through the vent.

[0008] According to the first invention, in the resin injection process, air (bubbles) remaining in the cavity is pushed out by the injection pressure of the thermosetting resin and discharged to the vent as the pressure is repeatedly increased and decreased by the opening and closing process. As a result, the air in the cavity can be properly discharged, and the generation of voids in the molded fiber-reinforced resin product can be properly suppressed.

[0009] The second invention of the present invention is a method for manufacturing a fiber-reinforced resin molded product, wherein, in the first invention described above, the repeated opening and closing step is a step in which, after the depressurization step, each of the opening and closing valves arranged at multiple locations in the flow direction of the suction pipe connected to the vent is closed, and thereafter, each of the opening and closing valves is opened sequentially from the upstream side closer to the cavity, leaving the opening and closing valve at the downstream end, so that the pressure holding and depressurization within the cavity are repeated due to the action of the vacuum pressure between the opening and closing valves arranged downstream.

[0010] According to the second invention, by setting multiple on-off valves in a suction pipe connected to a vent, and opening each on-off valve that is closed in a reduced pressure state sequentially from the upstream side, it is possible to easily and appropriately control the repeated pressure holding and depressurization in the cavity and prevent the thermosetting resin from leaking out from the on-off valve at the downstream end. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view showing the schematic configuration of a fiber-reinforced resin molded product according to the first embodiment. [Figure 2] This flowchart shows a method for manufacturing fiber-reinforced resin molded products. [Figure 3] This diagram shows the process of setting the reinforcing fiber base material into the mold. [Figure 4] This is a diagram showing the shaping process. [Figure 5] This figure shows the process of cutting the ends of the reinforcing fiber base material while the mold is still clamped in place. [Figure 6] This figure shows the process of moving the reinforcing fiber base material to the lower molding mold while keeping it in close contact with the upper molding mold after the mold has been opened. [Figure 7] This diagram shows the process of clamping the upper mold onto the lower mold. [Figure 8] This diagram shows the process of opening the upper mold from the lower mold. [Figure 9] This diagram shows the process of clamping the upper molding mold onto the lower molding mold. [Figure 10] This diagram shows the process of reducing the pressure inside the cavity of the mold. [Figure 11] This diagram shows the process of filling the cavity with thermosetting resin. [Figure 12] This diagram shows the process of opening the upstream on-off valve. [Figure 13] This diagram shows the process in which the next valve is opened. [Figure 14] This diagram shows the process of opening the next valve. [Figure 15] This diagram shows how air is expelled from the cavity through repeated opening and closing processes. [Figure 16] This diagram shows the process of removing the product by opening the upper mold from the lower mold. [Modes for carrying out the invention]

[0012] The following describes embodiments for implementing the present invention with reference to the drawings.

[0013] 《First Embodiment》 (Method for manufacturing the fiber reinforced resin molded product 1) First, a fiber reinforced resin molded product (hereinafter referred to as the molded product) 1 according to the first embodiment of the present invention and its manufacturing method (hereinafter referred to as this manufacturing method) will be described with reference to FIGS. 1 to 16. In the following description, when no specific reference figure is shown, or when there is no reference numeral corresponding to the reference figure, any one of FIGS. 1 to 16 shall be appropriately referred to.

[0014] As shown in FIG. 1, the molded product 1 is configured as a frame of the seat back 101 of the vehicle seat 100. Specifically, the molded product 1 is configured as a shell-shaped frame curved in a concave shape that can support so as to wrap around the back of the seated person. On the front surface of the molded product 1 which is the above shell-shaped frame, a back pad (not shown) which is a cushion material for elastically supporting the back of the seated person is provided.

[0015] The molded product 1 is made of a composite material formed by impregnating a sheet-shaped reinforcing fiber base material 2 with a thermosetting resin 3 and integrally thermosetting it. The molded product 1 is shaped such that the whole is gently curved in a concave shape and the peripheral portion is bent so as to warp.

[0016] The molded product 1 is molded using the RTM (Resin Transfer Molding) molding method. Specifically, as shown in FIG. 2, the molded product 1 is molded in the order of a shaping process S1, a base material cutting process S2, a mold moving and setting process S3, a decompression process S4, a resin injection process S5, an opening and closing repeating process S6, and a demolding process S7. The decompression process S4, the resin injection process S5, and the opening and closing repeating process S6 are processes corresponding to the resin molding process SR.

[0017] The shaping process S1 is a process in which a sheet-like reinforcing fiber base material 2 is shaped into a product shape using a shaping mold 10, as shown in Figures 3 and 4. The shaping mold 10 comprises an upper shaping mold 11 and a lower shaping mold 12, both equipped with shaping surfaces 11A and 12A that can shape the reinforcing fiber base material 2 to match the product shape. The base material cutting process S2 is a process in which the ends of the shaped reinforcing fiber base material 2 are cut by a cutting blade 13 provided inside the shaping mold 10 to form the product shape, as shown in Figure 5.

[0018] The mold transfer and setting process S3 is a process in which, after opening the mold shaping mold 10, the shaped reinforcing fiber base material 2 is moved and set onto the lower molding mold 22, which is the lower mold of the resin molding mold 20, while keeping it in close contact with the upper molding mold 11, which is the upper mold of the mold shaping mold 10. The depressurization process S4 is a process in which, after clamping the molding mold 20 as shown in Figure 9, the cavity C in which the reinforcing fiber base material 2 is set is vacuumed through the vent 21C, as shown in Figure 10.

[0019] The resin injection process S5 is a process in which thermosetting resin 3 is injected and filled into the depressurized cavity C, as shown in Figure 11. The opening and closing repeating process S6 is a process in which the vent 21C is repeatedly opened and closed during the resin injection process S5, as shown in Figures 12 to 14, thereby repeatedly maintaining and depressurizing the pressure inside the cavity C through the vent 21C. Through this process, as shown in Figure 15, the air (bubbles) inside the cavity C is crushed and gradually discharged to the outside. The demolding process S7 is a process in which the molded product 1, which has been formed by thermosetting by heating the mold 20, is demolded along with the opening of the mold 20, as shown in Figure 16.

[0020] As shown in Figures 6 to 8, the mold 20 comprises an upper mold 21 and a lower mold 22, both equipped with molding surfaces 21A and 22A capable of resin molding the reinforcing fiber base material 2 set in its cavity C into a shape that matches the shaped product. The shaping surface 11A of the upper mold 11 is formed to correspond to the surface shape of the molding surface 21A of the upper mold 21, i.e., to be substantially the same surface shape. Similarly, the shaping surface 12A of the lower mold 12 is formed to correspond to the surface shape of the molding surface 22A of the lower mold 22, i.e., to be substantially the same surface shape.

[0021] According to this manufacturing method, in the mold transfer and setting step S3 (see Figures 6 to 8), the shaped reinforcing fiber base material 2 can be moved to the molding lower mold 22 while remaining in close contact with the shaping upper mold 11 and set in the molding lower mold 22. In other words, the shaped reinforcing fiber base material 2 can be transferred to the molding lower mold 22 while remaining in close contact with the shaping upper mold 11 without being removed. Therefore, the reinforcing fiber base material 2 can be transferred to the molding lower mold 22 without losing its shape, even without using a sealing agent to heat-cure the reinforcing fiber base material 2 into its shaped form.

[0022] Furthermore, according to this manufacturing method, the thermosetting resin 3 can be impregnated into the reinforcing fiber substrate 2 and thermoset while the air in the cavity C is properly discharged through the repeated opening and closing process S6 (see Figures 12 to 14). Therefore, the occurrence of voids in the molded product 1 can be properly suppressed.

[0023] The details of each of the above-mentioned processes will be explained in order below. First, the shaping process S1 will be explained with reference to Figures 3 and 4. As shown in Figure 3, in the shaping process S1, first, the sheet-like reinforcing fiber base material 2 is set together with the thin film surface layer 4 on the shaping surface 12A of the lower shaping mold 12, which is the lower mold of the shaping mold 10.

[0024] The reinforcing fiber base material 2 consists of a laminate formed by stacking multiple layers of carbon fiber nonwoven fabric. The reinforcing fiber base material 2 may be made of glass fibers or aramid fibers in addition to carbon fibers. Furthermore, the reinforcing fiber base material 2 may be made of woven fabric or knitted fabric in addition to nonwoven fabric. The surface layer film 4 is a synthetic resin film that forms a thin film-like design surface on the surface of the molded product 1. The surface layer film 4 is set on the forming surface 12A of the forming mold 12 before the reinforcing fiber base material 2, and the reinforcing fiber base material 2 is set on top of it in a laminated manner.

[0025] Next, as shown in Figure 4, the upper mold 11, which is the upper mold of the forming mold 10, is clamped onto the lower mold 12. As a result, the surface film 4 and the reinforcing fiber base material 2 set on the lower mold 12 are pressed between the forming surface 12A of the lower mold 12 and the forming surface 11A of the upper mold 11, and are formed into a shape along these forming surfaces 12A and 11A.

[0026] Next, as shown in Figure 5, in the base material cutting process S2, with the shaping mold 10 still clamped, the ends of the reinforcing fiber base material 2 and surface film 4 inside the shaping mold 10 are cut by a cutting blade 13 provided inside the shaping mold 10. Although not specifically shown in the illustration, the cutting blade 13 is set inside the upper shaping mold 11 and, together with the clamping, is pressed towards the shaping surface 12A of the lower shaping mold 12, thereby cutting the ends of the reinforcing fiber base material 2 and surface film 4 into the product shape.

[0027] In the above-described substrate cutting process S2, the edges of the reinforcing fiber substrate 2 and the surface film 4 are cut, making cutting easier compared to a configuration where the edges are cut after resin molding, because the edges are not yet hardened. Furthermore, since the reinforcing fiber substrate 2 is made of nonwoven fabric, the cut surface can be made less prone to fraying.

[0028] Next, the mold transfer and setting process S3 will be explained with reference to Figures 6 to 8. As shown in Figure 6, in the mold transfer and setting process S3, first, the upper mold 11 is opened from the lower mold 12. At this time, a vacuum pump (not shown) is used to open the upper mold 11 while applying vacuum to bring the reinforcing fiber substrate 2 and the surface film 4 into close contact with the forming surface 11A of the upper mold 11 through the ventilation holes (not shown) formed in the upper mold 11.

[0029] As a result, the surface film 4 acts as a sealing material to enhance airtightness, and the reinforcing fiber base material 2 and the surface film 4 remain in close contact with the shape of the shaping surface 11A of the upper shaping mold 11, that is, they are removed from the lower shaping mold 12 together with the upper shaping mold 11 while maintaining their shaped form without being distorted.

[0030] Next, the opened upper mold 11 is moved onto the lower mold 22 of the mold 20, which is in the open position, and clamped to the lower mold 22 as shown in Figure 7. Specifically, the clamping of the upper mold 11 to the lower mold 22 is performed by passing a positioning pin provided on one of them through a hole in the other. Through this clamping, the reinforcing fiber base material 2 and surface film 4 attached to the upper mold 11 are set on the molding surface 22A of the lower mold 22.

[0031] The shaping surface 11A of the upper shaping mold 11 has substantially the same surface shape as the molding surface 21A of the upper molding mold 21. Therefore, by clamping the upper shaping mold 11 onto the lower molding mold 22, the reinforcing fiber base material 2 and the surface film 4, which are in close contact with the shaping surface 11A, are set to be positioned along the molding surface 22A of the lower molding mold 22.

[0032] Next, with the upper mold 11 still clamped to the lower mold 22, the vacuum applied to the upper mold 11 is released. This causes the reinforcing fiber substrate 2 and surface film 4, which were in close contact with the shaping surface 11A of the upper mold 11, to fall onto the molding surface 22A of the lower mold 22. Next, as shown in Figure 8, the upper mold 11 is opened from the lower mold 22. This causes only the upper mold 11 to be opened from the lower mold 22, while the reinforcing fiber substrate 2 and surface film 4 remain on the molding surface 22A of the lower mold 22.

[0033] After the mold is opened, the reinforcing fiber base material 2 and the surface film 4 do not lift up from the molding surface 22A of the lower mold 22, but are retained in the shape of the product that conforms to the shape of the molding surface 22A, i.e., in their formed shape. This is because the reinforcing fiber base material 2, which is made of carbon fiber nonwoven fabric, has properties that make it easy to maintain its formed shape and is resistant to springback even after being unloaded by opening the mold.

[0034] Furthermore, the surface film 4, being composed of a thin, flexible film, has weaker restorative force compared to the reinforcing fiber base material 2, and does not exert enough elastic force to deform the reinforcing fiber base material 2. Therefore, in this mold transfer and setting process S3, the formed reinforcing fiber base material 2 and surface film 4 can be set and transferred to the molding lower mold 22 without losing their shape, while remaining in close contact with the forming upper mold 11.

[0035] Next, the resin molding process SR (reduced pressure process S4, resin injection process S5, and opening / closing repeating process S6) will be explained with reference to Figures 9 to 14. As shown in Figure 9, first, in the reduced pressure process S4, the upper mold 21 is clamped onto the lower mold 22, which is set with the reinforcing fiber substrate 2 and the surface film 4.

[0036] Then, as shown in Figure 10, the cavity C formed by the molding surface 21A of the clamped upper mold 21 and the molding surface 22A of the lower mold 22 is evacuated using a vacuum pump 40 connected via a suction pipe 41. The vacuum pump 40 applies suction pressure to the cavity C from the outside via the vent 21C formed in the upper mold 21 and the suction pipe 41 connected thereto, thereby reducing the pressure inside the cavity C. The suction pipe 41 is provided with four on-off valves V1 to V4 at positions in the direction of flow. Each on-off valve V1 to V4 is spaced apart from each other and can be individually opened or closed via a control device (not shown).

[0037] Next, as shown in Figure 11, liquid thermosetting resin 3 is injected into the depressurized cavity C using the resin supply device 30. The resin supply device 30 injects the liquid thermosetting resin 3 into the cavity C through the nozzle 31 via the injection hole 21B formed in the upper mold 21.

[0038] The thermosetting resin 3 used in this embodiment is a two-component epoxy resin consisting of a main component and a curing agent. The resin supply device 30 mixes the main component and curing agent of the epoxy resin in a predetermined mixing ratio in a mixing head (not shown), and injects the mixture into the cavity C through the injection hole 21B via a nozzle 31 at the tip of the mixing head.

[0039] The thermosetting resin 3 may consist of epoxy resin, phenolic resin, unsaturated polyester resin, vinyl ester resin, or urethane resin. Although not shown in the figure, a sealing member is provided on the periphery of the lower surface of the upper molding mold 21, which is pressed between it and the upper surface of the lower molding mold 22 during clamping to seal the periphery of the cavity C.

[0040] In the depressurization process S4 shown in Figure 10, after clamping the upper mold 21 onto the lower mold 22, first, the gas (air) in the cavity C is discharged to the outside through the vent 21C and suction pipe 41 using a vacuum pump 40, thereby reducing the pressure inside the cavity C to a predetermined negative pressure. At this time, the four on-off valves V1 to V4 are left open.

[0041] Then, once the pressure inside cavity C has been reduced to a predetermined negative pressure, the four on-off valves V1 to V4 are closed. As a result, in addition to cavity C, each space partitioned by the four on-off valves V1 to V4 is also kept in an airtight state with a predetermined negative pressure. After closing the four on-off valves V1 to V4, the operation of the vacuum pump 40 is stopped.

[0042] Subsequently, in the resin injection process S5 shown in Figure 11, liquid thermosetting resin 3 is injected into the depressurized cavity C from the resin supply device 30. This injection under reduced pressure ensures that the liquid thermosetting resin 3 fills the cavity C evenly. As a result, the liquid thermosetting resin 3 injected into the cavity C impregnates the reinforcing fiber substrate 2 within the cavity C and flows through the cavity C, pushing out any remaining air bubbles in the reinforcing fiber substrate 2.

[0043] Since the thermosetting resin 3 injected into cavity C is made of epoxy resin, it has low viscosity in its liquid state. Therefore, even if the injection pressure from the resin supply device 30 is low, the thermosetting resin 3 is filled so that it spreads widely throughout cavity C and is properly impregnated into the reinforcing fiber substrate 2. As the liquid thermosetting resin 3 fills cavity C, air bubbles in cavity C rise to the surface and move towards vent 21C.

[0044] When the thermosetting resin 3 is filled into cavity C, the injection pressure of the thermosetting resin 3 is applied to cavity C, which is maintained by the closing of each on-off valve V1 to V4, and the internal pressure inside cavity C increases. As a result, as shown in Figure 15, if air bubbles remain in cavity C, these bubbles are crushed by the internal pressure of cavity C. However, as the bubbles are crushed, the internal pressure of cavity C also gradually increases, and once the internal pressure exceeds a certain level, the injection pressure from the resin supply device 30 alone is no longer sufficient to crush the bubbles further.

[0045] Next, as shown in Figures 12 to 14, in the opening and closing repetition process S6, while continuing to inject the thermosetting resin 3 by the resin supply device 30, each on-off valve V1 to V3 is opened sequentially from the upstream side (on-off valve V1) closest to the cavity C. As a result, the pressure inside the cavity C is repeatedly maintained and depressurized, and any air bubbles remaining inside the cavity C are gradually discharged into the vent 21C by being pushed aside by the injection pressure of the thermosetting resin 3.

[0046] Specifically, as shown in Figure 12, in the repeated opening and closing process S6, the upstream on-off valve V1 is opened first. As a result, the negative pressure between the opened on-off valve V1 and the closed on-off valve V2 causes the pressure inside the cavity C to decrease.

[0047] Subsequently, as the injection of thermosetting resin 3 by the resin supply device 30 continues, the internal pressure of cavity C rises again above a certain level and reaches a pressure-holding state. During this time, some of the thermosetting resin 3 filled in cavity C leaks out from vent 21C into suction pipe 41, but the leakage of thermosetting resin 3 is limited to just before the second on-off valve V2 from the upstream side, which is closed.

[0048] Next, as shown in Figure 13, the second on-off valve V2 from the upstream side is opened. As a result, the negative pressure between the opened on-off valve V2 and the closed on-off valve V3 reduces the pressure inside cavity C. Subsequently, as the injection of thermosetting resin 3 by the resin supply device 30 continues, the internal pressure of cavity C rises again to above a certain level and reaches a holding pressure state. During this time, some of the thermosetting resin 3 filled in cavity C leaks from the vent 21C into the suction pipe 41, but the leakage of thermosetting resin 3 is limited to before the third on-off valve V3 from the upstream side, which is closed.

[0049] Next, as shown in Figure 14, the third on-off valve V3 from the upstream side is opened. As a result, the negative pressure between the opened on-off valve V3 and the closed on-off valve V4 reduces the pressure inside cavity C. Subsequently, as the injection of thermosetting resin 3 by the resin supply device 30 continues, the internal pressure of cavity C rises again to above a certain level and reaches a holding pressure state. During this time, some of the thermosetting resin 3 filled in cavity C leaks from the vent 21C into the suction pipe 41, but the leakage of thermosetting resin 3 is limited to before the fourth on-off valve V4 from the upstream side, which is closed.

[0050] The stepwise opening of the above-mentioned valves V1 to V3 repeatedly reduces pressure and maintains pressure within the cavity C. After the opening and closing process S6, the thermosetting resin 3 is filled into the cavity C, and then the injection of the thermosetting resin 3 by the resin supply device 30 is stopped, and the cavity C is maintained at a pressure. In this state, as the mold 20 is heated, the thermosetting resin 3 in the cavity C is heat-cured, thereby forming a molded product 1 in which the surface film 4 and reinforcing fiber substrate 2 and the thermosetting resin 3 are integrated.

[0051] Subsequently, in the demolding process S7 shown in Figure 16, the mold 20 is opened and the molded product 1 is removed from the lower mold 22. Through these steps, a molded product 1 without voids on its surface can be formed.

[0052] In summary, the manufacturing method for the fiber-reinforced resin molded product 1 according to this embodiment has the following configuration. The reference numerals in parentheses below correspond to the respective configurations shown in the above embodiment.

[0053] In other words, the method for manufacturing the fiber-reinforced resin molded product (1) is a method for manufacturing the fiber-reinforced resin molded product (1) obtained by impregnating a sheet-shaped reinforcing fiber base material (2) with a thermosetting resin (3) and then thermosetting it. The method for manufacturing the fiber-reinforced resin molded product (1) includes a depressurization step (S4), a resin injection step (S5), and an opening and closing repeat step (S6). The depressurization step (S4) is a step of evacuating the cavity (C) of the mold (20) in which the reinforcing fiber base material (2) is set through a vent (21C).

[0054] The resin injection process (S5) is a process of injecting and filling a depressurized cavity (C) with a thermosetting resin (3). The repeated opening and closing process (S6) is a process of repeatedly closing and opening the vent (21C) during the resin injection process (S5), thereby repeatedly maintaining and depressurizing the pressure inside the cavity (C) through the vent (21C). With the above configuration, in the resin injection process (S5), any air (bubbles) remaining inside the cavity (C) is pushed out by the injection pressure of the thermosetting resin (3) and discharged into the vent (21C) as the pressure is repeatedly maintained and depressurized by the repeated opening and closing process (S6). As a result, the air inside the cavity (C) can be properly discharged, and the generation of voids in the molded fiber-reinforced resin product (1) can be properly suppressed.

[0055] Furthermore, the repeated opening and closing process (S6) involves closing the on-off valves (V1~V4) located at multiple points in the flow direction of the suction pipe (41) connected to the vent (21C) after the depressurization process (S4), and then opening each on-off valve (V1~V3) in order from the upstream side closer to the cavity (C), leaving the on-off valve (V4) at the downstream end. This process repeats the holding and depressurization of pressure within the cavity (C) due to the action of the vacuum pressure between the on-off valves (V2~V4) located downstream. In this way, by setting multiple on-off valves (V1~V4) in the suction pipe (41) connected to the vent (21C), and opening each on-off valve (V1~V3) that was closed in the depressurized state in order from the upstream side, it is possible to easily and appropriately control the repeated holding and depressurization of pressure within the cavity (C) and prevent the thermosetting resin (3) from leaking out from the on-off valve (V4) at the downstream end.

[0056] Regarding other embodiments: Although the embodiments of the present invention have been described above using one embodiment, the present invention can be implemented in various forms other than those described above.

[0057] 1. The manufacturing method for the fiber-reinforced resin molded article of the present invention may be any so-called RTM (Resin Transfer Molding) molding method, or it may be a VaRTM (Vacuum assisted Resin Transfer Molding) molding method. Furthermore, the fiber-reinforced resin molded article may be applied not only to seats for vehicles such as automobiles and railways, but also to seats for vehicles other than automobiles, such as aircraft and ships. It may also be applied to interior parts of vehicles.

[0058] 2. The repeated opening and closing process may involve repeatedly opening and closing a single valve to repeatedly create and remove pressure within the cavity. The number of repetitions of pressure retention and pressure removal within the cavity in the repeated opening and closing process is not limited to a specific number, but can be set appropriately according to conditions such as the shape of the formed reinforcing fiber base material and the type of thermosetting resin selected. [Explanation of symbols]

[0059] 1. Fiber-reinforced resin molded product 2. Reinforcement fiber base material 3 Thermosetting resin 4. Surface film 10 Shaping mold 11. Formation type 11A Shaping surface 12 Imprinting mold 12A Shaping surface 13 Cutting blade 20 mold 21 Upper mold 21A Molding surface 21B Injection hole 21C Bent 22 Lower mold 22A Molding surface C Cavity 30 Resin supply device 31 nozzles 40 Vacuum pump 41 Suction tube V1~V4 Shut-off valves S1 Shaping process S2 Base material cutting process S3 Type Transfer Set Process S4 Depressurization Process S5 Resin injection process S6 Repeated opening and closing process S7 Demolding process SR resin molding process 100 Vehicle Seats 101 Seatback

Claims

[Claim 1] A method for producing a fiber-reinforced resin molded product obtained by impregnating a sheet-like reinforcing fiber substrate with a thermosetting resin and then thermosetting it, A vacuum step is performed by evacuating the cavity of the mold in which the reinforcing fiber substrate is set through a vent. A resin injection step in which the thermosetting resin is injected and filled into the depressurized cavity, The process includes an opening and closing repetition step in which the vent is repeatedly opened and closed during the resin injection step, thereby repeatedly maintaining and depressurizing the pressure inside the cavity through the vent. A method for manufacturing a fiber-reinforced resin molded product, wherein the repeated opening and closing step involves closing each of the on-off valves arranged at multiple locations in the flow direction of the suction pipe connected to the vent after the depressurization step, and then opening each of the on-off valves in order from the upstream side closer to the cavity, except for the on-off valve at the downstream end, so that the pressure holding and depressurization within the cavity are repeated due to the action of the vacuum pressure between the on-off valves arranged downstream.

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