JP2024074361A - Manufacturing method of fiber reinforced plastic molded product - Google Patents

Abstract

The present invention provides a method for producing a fiber-reinforced resin molded product capable of suppressing the occurrence of voids.
[Solution] A manufacturing method for a fiber-reinforced resin molded product 1 obtained by impregnating a sheet-like reinforcing fiber substrate 2 with a thermosetting resin 3 and thermally curing the resin, the method including a depressurization step of evacuating a cavity C of a molding die 20 in which the reinforcing fiber substrate 2 is set via a vent 21C, a resin injection step S5 of injecting the thermosetting resin 3 into the depressurized cavity C to fill it, and an opening and closing repetition step of repeatedly closing and opening the vent 21C during the resin injection step S5 to repeatedly maintain and reduce pressure in the cavity C via the vent 21C.
[Selected figure] Figure 11

Description

The present invention relates to a method for producing a fiber-reinforced plastic molded product. More specifically, the present invention relates to a method for producing a fiber-reinforced plastic molded product obtained by impregnating a sheet-shaped reinforcing fiber substrate with a thermosetting resin and thermally curing the resin.

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

Next, after drawing a vacuum inside the clamped cavity, a thermosetting resin is injected into the cavity, and the thermosetting resin is allowed to fill the cavity while impregnating the reinforcing fiber substrate. After filling, the molding die is heated, whereby the thermosetting resin impregnated in the reinforcing fiber substrate is thermally cured, and a fiber-reinforced resin molded product is formed, which is a resin molded product integrated with the reinforcing fiber substrate.

JP 2007-1179 A

In the configuration described in Patent Document 1, the thermosetting resin is injected while the cavity is evacuated, but the air (air bubbles) in the cavity are not completely expelled, resulting in the formation of voids in the molded product. Therefore, the present invention provides a method for manufacturing a fiber-reinforced resin molded product that can suppress the formation of voids.

To solve the above problems, the manufacturing method of the fiber-reinforced plastic molded product of the present invention takes the following steps.

That is, the first invention of the present invention is a method for producing a fiber-reinforced plastic molded product obtained by impregnating a sheet-like reinforcing fiber substrate with a thermosetting resin and thermally curing the resin, and includes a depressurization process in which a cavity of a mold in which the reinforcing fiber substrate is set is evacuated through a vent, a resin injection process in which the depressurized cavity is filled by injecting the thermosetting resin, and an opening and closing repetition process in which the vent is repeatedly closed and opened during the resin injection process to repeatedly maintain and reduce the pressure in the cavity through the vent.

According to the first invention, in the resin injection process, the air (air bubbles) remaining in the cavity is pushed aside by the injection pressure of the thermosetting resin and discharged to the vent as the pressure is repeatedly maintained and reduced by the repeated opening and closing process. As a result, the air in the cavity can be properly discharged, and the occurrence of voids in the fiber-reinforced resin molded product can be properly suppressed.

The second invention of the present invention is a method for manufacturing a fiber-reinforced plastic molded product according to the first invention, in which the repeated opening and closing process is a process in which, after the depressurization process, each of the on-off valves arranged at multiple locations in the flow direction of the suction pipe connected to the vent is closed, and then, leaving only the on-off valve at the downstream end, each of the on-off valves is opened in order from the upstream side closest to the cavity, so that the vacuum pressure between the on-off valves arranged downstream repeatedly maintains and reduces the pressure in the cavity.

According to the second invention, by setting up multiple on-off valves in the suction pipe connected to the vent and opening each on-off valve, which is closed in a reduced pressure state, in sequence starting from the upstream side, a simple configuration is achieved, which makes it possible to easily and appropriately repeat pressure maintenance and reduction in pressure within the cavity and control so as to prevent the thermosetting resin from leaking out of the on-off valve at the downstream end.

1 is a perspective view showing a schematic configuration of a fiber-reinforced plastic molded product according to a first embodiment. FIG. 1 is a flowchart showing a method for manufacturing a fiber-reinforced plastic molded product. FIG. 2 is a diagram showing a step of setting a reinforcing fiber substrate in a shaping mold. FIG. A diagram showing a process of cutting the end of a reinforcing fiber substrate while the shaping mold is clamped. FIG. 13 is a diagram showing a process in which the reinforcing fiber substrate is moved to the lower molding die while being in close contact with the upper shaping die after the die is opened. FIG. 13 is a diagram showing the process of clamping the shaping upper die to the molding lower die. FIG. 2 is a diagram showing the process of opening the shaping upper die from the molding lower die. 11A and 11B are diagrams showing a process of clamping an upper forming die to a lower forming die. 11A to 11C are diagrams showing a process of reducing the pressure inside the cavity of the mold. 11A to 11C are diagrams showing a process of filling a cavity with a thermosetting resin. 11A and 11B are diagrams illustrating a process in which an upstream on-off valve is opened. FIG. 13 is a diagram showing the next process in which the on-off valve is opened. FIG. 13 is a diagram showing the process in which the next on-off valve is opened. 13A and 13B are diagrams showing how air is discharged from the cavity by repeated opening and closing processes. 11 is a diagram showing a process of opening the upper molding die from the lower molding die to demold the product. FIG.

Below, the form for implementing the present invention is explained with reference to the drawings.

First Embodiment
(Method for manufacturing fiber reinforced resin molded product 1)
First, a fiber-reinforced plastic molded product (hereinafter, molded product) 1 according to a first embodiment of the present invention and a manufacturing method thereof (hereinafter, this manufacturing method) will be described with reference to Figures 1 to 16. In the following description, when a specific reference figure is not shown or when a reference figure does not have a corresponding reference number, any of Figures 1 to 16 will be appropriately referred to.

As shown in FIG. 1, the molded product 1 is configured as a frame for the seat back 101 of the vehicle seat 100. Specifically, the molded product 1 is configured as a shell-shaped frame curved into a concave shape that can support the back of a seated occupant by enveloping it. A back pad (not shown) that is a cushioning material for elastically supporting the back of the seated occupant is provided on the front surface of the molded product 1, which is the shell-shaped frame.

The molded product 1 is made of a composite material that is made by impregnating a sheet-like reinforcing fiber substrate 2 with a thermosetting resin 3 and thermosetting the resin to form an integral structure. The molded product 1 is gently curved in a concave shape as a whole, and the peripheral portion is bent so that it warps back.

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 following order: shaping process S1, substrate cutting process S2, mold transfer and setting process S3, depressurizing process S4, resin injection process S5, opening and closing repetition process S6, and demolding process S7. The depressurizing process S4, resin injection process S5, and opening and closing repetition process S6 correspond to the resin molding process SR.

As shown in Figures 3 and 4, the shaping process S1 is a process in which a sheet-like reinforcing fiber substrate 2 is shaped into a product shape using a shaping mold 10. The shaping mold 10 is equipped with an upper shaping mold 11 and a lower shaping mold 12 equipped with shaping surfaces 11A and 12A that can shape the reinforcing fiber substrate 2 into a shape that matches the product shape. The substrate cutting process S2 is a process in which the end of the shaped reinforcing fiber substrate 2 is cut by a cutting blade 13 provided in the shaping mold 10 to form the product shape, as shown in Figure 5.

As shown in Figures 6 to 8, the mold transfer and setting process S3 is a process in which, after opening the shaping mold 10, the shaped reinforcing fiber substrate 2 is moved and set to the molding lower mold 22, which is the lower mold of the resin molding mold 20, while being in close contact with the shaping upper mold 11, which is the upper mold of the shaping mold 10. The depressurization process S4 is a process in which, after closing the molding mold 20 as shown in Figure 9, the cavity C in which the reinforcing fiber substrate 2 is set is evacuated via the vent 21C as shown in Figure 10.

The resin injection process S5 is a process of injecting thermosetting resin 3 into the depressurized cavity C to fill it, as shown in FIG. 11. The opening and closing repetition process S6 is a process of repeatedly holding and depressurizing the cavity C via the vent 21C by repeatedly opening and closing the vent 21C during the resin injection process S5, as shown in FIGS. 12 to 14. This process causes the air (air bubbles) in the cavity C to be crushed and gradually discharged to the outside, as shown in FIG. 15. The demolding process S7 is a process of demolding the molded product 1 molded by thermosetting due to heating of the mold 20 together with the opening of the mold 20, as shown in FIG. 16.

As shown in Figures 6 to 8, the molding die 20 comprises an upper molding die 21 and a lower molding die 22 with molding surfaces 21A, 22A that can resin mold the reinforcing fiber substrate 2 set in the cavity C into a shape that matches the shaped product shape. The molding surface 11A of the upper molding die 11 is formed in a surface shape that corresponds to the molding surface 21A of the upper molding die 21, i.e., a substantially identical surface shape. The molding surface 12A of the lower molding die 12 is formed in a surface shape that corresponds to the molding surface 22A of the lower molding die 22, i.e., a substantially identical surface shape.

According to this manufacturing method, the mold transfer and setting step S3 (see Figures 6 to 8) allows the shaped reinforcing fiber substrate 2 to be moved to the lower molding mold 22 while still in close contact with the upper shaping mold 11 and set in the lower molding mold 22. That is, the shaped reinforcing fiber substrate 2 can be transferred onto the lower molding mold 22 without being removed from the upper shaping mold 11 and while still in close contact with the substrate. Therefore, the reinforcing fiber substrate 2 can be transferred onto the lower molding mold 22 without losing its shape, even without using a sealing agent to thermally cure the reinforcing fiber substrate 2 into the shaped shape.

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

The details of each of the above-mentioned steps will be described below in order. First, the shaping step S1 will be described with reference to Figures 3 and 4. As shown in Figure 3, in the shaping step S1, the sheet-like reinforcing fiber substrate 2 is first set together with the thin-film surface film 4 on the shaping surface 12A of the shaping lower mold 12, which is the lower mold of the shaping mold 10.

The reinforcing fiber substrate 2 is made of a laminate of multiple layers of carbon fiber nonwoven fabric. The reinforcing fiber substrate 2 may be made of glass fiber or aramid fiber, in addition to carbon fiber. The reinforcing fiber substrate 2 may be made of woven or knitted fabric, in addition to nonwoven fabric. The surface film 4 is a synthetic resin film that forms a thin-film design surface on the surface of the molded product 1. The surface film 4 is set on the shaping surface 12A of the shaping lower mold 12 before the reinforcing fiber substrate 2, and the reinforcing fiber substrate 2 is set on top of it in a layered manner.

Next, as shown in FIG. 4, the upper shaping mold 11, which is the upper mold of the shaping mold 10, is clamped to the lower shaping mold 12. As a result, the surface film 4 and the reinforcing fiber substrate 2 set on the lower shaping mold 12 are pressed and sandwiched between the shaping surface 12A of the lower shaping mold 12 and the shaping surface 11A of the upper shaping mold 11, and are shaped to fit these shaping surfaces 12A, 11A.

Next, as shown in FIG. 5, in the substrate cutting step S2, the ends of the reinforcing fiber substrate 2 and the surface film 4 in the shaping mold 10 are cut by a cutting blade 13 provided in the shaping mold 10 while the shaping mold 10 is still closed. The cutting blade 13, although not specifically shown, is set in the shaping upper mold 11 and is configured to cut the ends of the reinforcing fiber substrate 2 and the surface film 4 into the product shape by being pressed toward the shaping surface 12A of the shaping lower mold 12 as the mold is closed.

By cutting the ends of the reinforcing fiber substrate 2 and the surface film 4 in the substrate cutting step S2, the cutting can be performed more easily than in a configuration in which the ends are cut after resin molding because the ends have not yet hardened. In addition, because the reinforcing fiber substrate 2 is made of nonwoven fabric, the cut surfaces are less likely to unravel.

Next, the mold moving and setting step S3 will be described with reference to Figures 6 to 8. As shown in Figure 6, in the mold moving and setting step S3, first, the shaping upper mold 11 is opened from the shaping lower mold 12. At that time, the shaping upper mold 11 is opened while drawing a vacuum using a vacuum pump (not shown) through an air hole (not shown) formed in the shaping upper mold 11 so that the reinforcing fiber substrate 2 and the surface film 4 are in close contact with the shaping surface 11A of the shaping upper mold 11.

As a result, the surface film 4 becomes a sealing material that increases airtightness, and the reinforcing fiber substrate 2 and the surface film 4 are removed from the lower shaping mold 12 together with the upper shaping mold 11 while remaining in close contact with the shape of the shaping surface 11A of the upper shaping mold 11, i.e., while maintaining the shaped shape without collapsing.

Next, the open shaping upper die 11 is moved onto the lower die 22 of the molding die 20 in the open state, and is clamped to the lower die 22 as shown in FIG. 7. Specifically, the shaping upper die 11 is clamped to the lower die 22 by positioning the positioning pin provided on one of the shaping upper die 11 through the hole on the other die. By clamping, the reinforcing fiber substrate 2 and the surface film 4 attached to the shaping upper die 11 are set on the molding surface 22A of the lower die 22.

The shaping surface 11A of the shaping upper mold 11 has a surface shape that is approximately the same as the molding surface 21A of the forming upper mold 21. Therefore, by clamping the shaping upper mold 11 to the forming lower mold 22, the reinforcing fiber substrate 2 and the surface film 4 that are in close contact with the shaping surface 11A are set in a state in which they are arranged along the molding surface 22A of the forming lower mold 22.

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

After the mold is opened, the reinforcing fiber substrate 2 and the surface film 4 do not float up from the molding surface 22A of the lower mold 22, and are maintained in the product shape that conforms to the shape of the molding surface 22A, that is, in the shaped shape. This is because the reinforcing fiber substrate 2 made of carbon fiber nonwoven fabric has a springback-resistant property that makes it easy to maintain the shaped shape even when the load is removed by opening the mold.

The surface film 4, being made of a thin, soft film, has a weaker restoring force than the reinforcing fiber substrate 2 and is not subject to a resilient force strong enough to deform the reinforcing fiber substrate 2. Therefore, this mold transfer setting process S3 allows the shaped reinforcing fiber substrate 2 and surface film 4 to be set and handed over to the lower molding mold 22 without losing their shape while still in close contact with the upper shaping mold 11.

Next, the resin molding process SR (pressure reduction process S4, resin injection process S5, and opening and closing repetition process S6) will be described with reference to Figures 9 to 14. As shown in Figure 9, first, in the pressure reduction process S4, the molding upper mold 21 is clamped to the molding lower mold 22 in which the reinforcing fiber substrate 2 and the surface film 4 are set.

As shown in FIG. 10, the cavity C formed by the molding surface 21A of the clamped upper molding die 21 and the molding surface 22A of the lower molding die 22 is evacuated using a vacuum pump 40 connected via a suction pipe 41. The vacuum pump 40 applies suction pressure from the outside into the cavity C via a vent 21C formed in the upper molding die 21 and a suction pipe 41 connected to the vent, thereby reducing the pressure inside the cavity C. The suction pipe 41 is provided with on-off valves V1 to V4 at four positions in the flow direction. The on-off valves V1 to V4 are provided with a space between each other and are individually switched on and off via a control device (not shown).

Next, as shown in FIG. 11, the liquid thermosetting resin 3 is injected into the depressurized cavity C using a resin supplying device 30. The resin supplying device 30 injects the liquid thermosetting resin 3 into the cavity C through a nozzle 31 from an injection hole 21B formed in the upper mold 21.

The thermosetting resin 3 used in this embodiment is a two-part mixed epoxy resin consisting of a base agent and a hardener. The resin supply device 30 mixes the epoxy resin base agent and hardener in a predetermined ratio by collision in a mixing head (not shown), and injects the mixture from a nozzle 31 at the tip of the mixing head through an injection hole 21B into the cavity C.

The thermosetting resin 3 may be made of epoxy resin, phenol resin, unsaturated polyester resin, vinyl ester resin, or urethane resin. Although not shown, a seal member is provided on the periphery of the lower surface of the upper molding die 21, which is pressed between the upper surface of the lower molding die 22 and the upper surface of the lower molding die 22 when the die is closed to seal the periphery of the cavity C.

In the depressurization step S4 shown in FIG. 10, after the upper molding die 21 is clamped to the lower molding die 22, the gas (air) in the cavity C is first exhausted to the outside via the vent 21C and the suction pipe 41 using the vacuum pump 40, and the pressure inside the cavity C is reduced to a predetermined negative pressure. At this time, the four on-off valves V1 to V4 are each kept open.

Then, when the pressure inside cavity C is 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 the pressure reduced to the predetermined negative pressure. After the four on-off valves V1 to V4 are closed, the operation of the vacuum pump 40 is stopped.

Then, in the resin injection step S5 shown in FIG. 11, liquid thermosetting resin 3 is injected from the resin supply device 30 into the depressurized cavity C. By injecting in this depressurized environment, the liquid thermosetting resin 3 is filled so that it is widespread throughout the cavity C. In addition, the liquid thermosetting resin 3 injected into the cavity C impregnates the reinforcing fiber substrate 2 in the cavity C and flows through the cavity C while pushing out any air bubbles remaining in the reinforcing fiber substrate 2.

The thermosetting resin 3 injected into the cavity C is made of epoxy resin, and therefore has low viscosity in a liquid state. Therefore, even if the injection pressure by the resin supply device 30 is low, the thermosetting resin 3 is filled so as to be widely distributed within the cavity C, and is properly impregnated into the reinforcing fiber substrate 2. As the liquid thermosetting resin 3 is filled into the cavity C, the air bubbles in the cavity C rise to the surface and move toward the vent 21C.

When the thermosetting resin 3 is filled into the cavity C, the injection pressure of the thermosetting resin 3 is applied to the cavity C, which is maintained at pressure by closing the on-off valves V1 to V4, and the internal pressure of the cavity C rises. As a result, as shown in FIG. 15, if any air bubbles remain in the cavity C, these bubbles are crushed by the internal pressure of the cavity C. However, as the air bubbles are crushed, the internal pressure of the cavity C also gradually rises, and once the internal pressure reaches a certain level, the air bubbles cannot be crushed any further by the injection pressure from the resin supply device 30 alone.

As shown in Figures 12 to 14, next, in the repeat opening and closing step S6, while continuing to inject thermosetting resin 3 by resin supply device 30, each of the opening and closing valves V1 to V3 is opened in order from the upstream side (opening and closing valve V1) close to cavity C. This repeatedly maintains and reduces pressure in cavity C, and any air bubbles remaining in cavity C are gradually expelled to vent 21C, pushed aside by the injection pressure of thermosetting resin 3.

Specifically, as shown in FIG. 12, in the repeating opening and closing process S6, first, the most upstream opening and closing valve V1 is opened. As a result, the pressure in cavity C is reduced by the action of the negative pressure between the open opening and closing valve V1 and the closed opening and closing valve V2.

After that, as the resin supply device 30 continues to inject the thermosetting resin 3, the internal pressure of the cavity C again rises above a certain level and is maintained at a constant pressure. During this time, some of the thermosetting resin 3 filled in the cavity C leaks out from the vent 21C into the suction pipe 41, but the leakage of the thermosetting resin 3 is limited to just before the second open/close valve V2 from the upstream side, which is closed.

Next, as shown in FIG. 13, the second on-off valve V2 from the upstream side is opened. This reduces the pressure inside the cavity C due to the negative pressure between the open on-off valve V2 and the closed on-off valve V3. After that, the resin supply device 30 continues to inject the thermosetting resin 3, so the internal pressure of the cavity C rises again to above a certain level and is maintained at a constant pressure. During this time, part of the thermosetting resin 3 filled in the cavity C leaks out from the vent 21C into the suction pipe 41, but the leakage of the thermosetting resin 3 is limited to just before the third on-off valve V3 from the upstream side, which is closed.

Next, as shown in FIG. 14, the third on-off valve V3 from the upstream side is opened. This reduces the pressure inside the cavity C due to the negative pressure between the open on-off valve V3 and the closed on-off valve V4. After that, the resin supply device 30 continues to inject the thermosetting resin 3, so the internal pressure of the cavity C rises again to above a certain level and is maintained at a constant pressure. During this time, part of the thermosetting resin 3 filled in the cavity C leaks out from the vent 21C into the suction pipe 41, but the leakage of the thermosetting resin 3 is limited to just before the fourth on-off valve V4 from the upstream side, which is closed.

By gradually opening the on-off valves V1 to V3, the cavity C is repeatedly depressurized and pressurized. After the cavity C is filled with the thermosetting resin 3 through the repeated opening and closing process S6, the injection of the thermosetting resin 3 by the resin supply device 30 is stopped and the cavity C is kept under pressure. In this state, the thermosetting resin 3 in the cavity C is thermally cured by heating the molding die 20, thereby forming a molded product 1 in which the surface film 4, reinforcing fiber substrate 2, and thermosetting resin 3 are integrated.

After that, in the demolding process S7 shown in FIG. 16, the molding die 20 is opened and the molded product 1 is removed from the lower mold 22. Through the above steps, a molded product 1 without voids on the surface can be molded.

In summary, the manufacturing method of the fiber-reinforced plastic molded product 1 according to this embodiment is configured as follows. Note that the reference characters in parentheses below correspond to the respective components shown in the above embodiment.

That is, the method for producing a fiber-reinforced plastic molded product (1) is a method for producing a fiber-reinforced plastic molded product (1) obtained by impregnating a sheet-shaped reinforcing fiber substrate (2) with a thermosetting resin (3) and thermally curing the resin. The method for producing a fiber-reinforced plastic molded product (1) includes a depressurizing step (S4), a resin injection step (S5), and a repeated opening and closing step (S6). The depressurizing step (S4) is a step of drawing a vacuum through a vent (21C) inside the cavity (C) of the mold (20) in which the reinforcing fiber substrate (2) is set.

The resin injection process (S5) is a process of injecting and filling the depressurized cavity (C) with thermosetting resin (3). The opening and closing repetition process (S6) is a process of repeatedly opening and closing the vent (21C) during the resin injection process (S5) to repeatedly maintain and reduce the pressure in the cavity (C) through the vent (21C). According to the above configuration, in the resin injection process (S5), the air (air bubbles) remaining in the cavity (C) is pushed aside by the injection pressure of the thermosetting resin (3) and discharged to the vent (21C) as the pressure maintenance and reduction in pressure are repeated in the opening and closing repetition process (S6). As a result, the air in the cavity (C) can be properly discharged, and the occurrence of voids in the fiber-reinforced resin molded product (1) to be molded can be properly suppressed.

In addition, the opening and closing repetition step (S6) is a step in which, after the depressurization step (S4), each of the on-off valves (V1 to V4) arranged at multiple positions in the flow direction of the suction pipe (41) connected to the vent (21C) is closed, and then each of the on-off valves (V1 to V3) is opened in order from the upstream side close to the cavity (C) except for the on-off valve (V4) at the downstream end, so that the pressure in the cavity (C) is repeatedly maintained and depressurized by the action of the vacuum pressure between the on-off valves (V2 to V4) arranged downstream. In this way, with a simple configuration in which multiple on-off valves (V1 to V4) are set in the suction pipe (41) connected to the vent (21C) and each of the on-off valves (V1 to V3) closed in a depressurized state is opened in order from the upstream side, it is possible to easily and appropriately perform repeated pressure maintenance and depressurization in the cavity (C) and control to prevent the thermosetting resin (3) from leaking from the on-off valve (V4) at the downstream end.

Other embodiments
Although one embodiment of the present invention has been described above, the present invention can be embodied in various forms other than the above embodiment.

1. The manufacturing method of the fiber-reinforced plastic molded product of the present invention may be one that uses the so-called RTM (Resin Transfer Molding) molding method, or may be one that uses VaRTM (Vacuum assisted Resin Transfer Molding) molding method. Furthermore, the fiber-reinforced plastic molded product may be applied to seats for vehicles such as automobiles and trains, as well as seats for vehicles other than vehicles such as aircraft and ships. It may also be applied to interior parts of vehicles.

2. The opening and closing repetition process may be a process in which pressure retention and pressure reduction within the cavity are repeatedly performed by repeatedly opening and closing one opening and closing valve. The number of times that pressure retention and pressure reduction within the cavity are repeated in the opening and closing repetition process is not limited to a specific number, and may be set appropriately depending on conditions such as the shape of the shaped reinforcing fiber substrate and the type of thermosetting resin selected.

LIST OF SYMBOLS 1 Fiber-reinforced resin molded product 2 Reinforcing fiber substrate 3 Thermosetting resin 4 Surface film 10 Shaping mold 11 Upper shaping mold 11A Shaping surface 12 Lower shaping mold 12A Shaping surface 13 Cutting blade 20 Molding mold 21 Upper shaping mold 21A Molding surface 21B Injection hole 21C Vent 22 Lower shaping mold 22A Molding surface C Cavity 30 Resin supply device 31 Nozzle 40 Vacuum pump 41 Suction pipe V1 to V4 Opening and closing valve S1 Shaping process S2 Substrate cutting process S3 Mold moving and setting process S4 Decompression process S5 Resin injection process S6 Opening and closing repeat process S7 Demolding process SR Resin molding process 100 Vehicle seat 101 Seat back

Claims (2)

A method for producing a fiber-reinforced resin molded product obtained by impregnating a sheet-shaped reinforcing fiber substrate with a thermosetting resin and thermally curing the resin,
a decompression step of drawing a vacuum through a vent inside the cavity of the mold in which the reinforcing fiber substrate is set;
a resin injection step of injecting the thermosetting resin into the depressurized cavity to fill it;
and an opening and closing repeating process of repeatedly closing and opening the vent during the resin injection process to repeatedly maintain and reduce pressure in the cavity via the vent. A method for producing a fiber-reinforced resin molded product according to claim 1,
A manufacturing method for a fiber-reinforced plastic molded product, in which the repeated opening and closing process is a process in which, after the depressurization process, 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 then, except for the opening and closing valve at the downstream end, each of the opening and closing valves is opened in order from the upstream side closest to the cavity, thereby repeatedly maintaining pressure and reducing pressure in the cavity due to the action of vacuum pressure between the opening and closing valves arranged downstream.

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