JP2012066397A - Method for manufacturing fiber-reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing fiber-reinforced plastic of outstanding quality, while eliminating a level difference and resin reservoir produced at the molding end by difference in the length of profile shape of preform and molding, and excluding trim processing after molding, in a vacuum RTM molding method to manufacture the fiber-reinforced plastic of curved surface shape.SOLUTION: In the method for manufacturing fiber-reinforced plastic, thickness of the fiber-reinforced plastic after resin curing is changed from thickness of preform 2, by: arranging the preform 2 comprising the reinforcement fiber base material on the mold 101 having a curved surface or bending shape; covering the preform 2 with bag materials 3 and carrying out vacuum suction of the core; and filling the resin 10 to the preform 2 and curing the preform 2, the preform 2 is formed beforehand by laminating the reinforcement fiber base materials of different width and/or length, so that the end face of the fiber-reinforced plastic may become a desired shape.

Description

  The present invention relates to a manufacturing method of fiber reinforced plastic (hereinafter also referred to as FRP) using a vacuum RTM (Resin Transfer Molding) molding method, and in particular, when manufacturing FRP having a curved surface shape, trim processing is performed after resin curing. It is related with the manufacturing method of FRP which can obtain FRP of the desired shape excellent in quality without doing.

  FRP is a lightweight material that can exhibit high mechanical properties, and is used in various fields. As typical FRP manufacturing methods, a prepreg method, an RTM (Resin Transfer Molding) method, a vacuum RTM molding method, and the like are known.

  The prepreg method is a molding method in which a sheet in which a reinforcing fiber called a prepreg is impregnated with a semi-cured resin is heated and pressed in a pressure cooker called an autoclave to cure the resin. The RTM method is a molding method in which reinforcing fibers are disposed in a cavity of a double-sided mold, a resin is injected into the cavity under pressure, and the resin is injected into the reinforcing fibers and cured.

  On the other hand, in the vacuum RTM molding method, reinforcing fibers are arranged on a mold, the entire reinforcing fibers are sealed with a bag material, the inside of the bag material is decompressed, and the inside of the bag material is decompressed and the external pressure (atmospheric pressure) The resin is injected into the reinforcing fiber using the pressure difference between the resin and the resin, the resin is cured, and after the curing, the mold is removed to obtain FRP. The vacuum RTM molding method does not require a pressurizing facility and can be manufactured with a very simple facility.

  In the manufacturing method of FRP, as disclosed in Patent Document 1, generally, after molding (resin curing), molding is performed for the purpose of adjusting the FRP to the exact size and removing the resin pool at the end. In many cases, a process of trimming (cutting) the end of the product is provided.

  As illustrated in FIG. 5 of Patent Document 2, in particular, when reinforcing fibers are arranged in a shape that may cause a difference in circumference between the inner layer and the outer layer, such as a curved surface, the difference in circumference at the end of the molded product. As a result, the reinforcing fiber layer is displaced by this amount, resulting in a level difference. Therefore, there is a problem in that a resin pool is generated at the level difference at the end of the molded product, and that portion becomes a defect in strength. Therefore, the resin reservoir is removed by trimming (cutting) the end of the molded product.

  In addition, in the molding method in which a resin is injected into a reinforcing fiber as in the RTM method, as shown in Patent Document 3, before the resin is injected, a reinforcing fiber structure called a preform is formed, The outline may be trimmed. In the case of using a double-sided mold, the thickness of the preform and the molded product is substantially equal, and there is no change in thickness, so that the shape of the preform can be the final shape of the FRP.

  On the other hand, as described in Patent Document 4, the vacuum RTM molding method injects and discharges resin to and from the preform, and the volume of the entire preform changes during molding. Therefore, the preform and FRP have an apparent thickness. There are different characteristics. Therefore, when manufacturing a molded product having a curved surface shape, the outer circumference (length of the outer shape) changes between the preform and the FRP, so that a step is generated at the end of the FRP after molding, and trim processing is performed. If not, a resin pool is formed, which causes a problem of strength defects. Further, in order to remove the resin reservoir, it is necessary to trim the FRP finally, which causes a problem of waste of materials and increase of waste.

JP-A-10-180757 JP 2002-059478 A JP 2007-118577 A JP 2004-130598 A

  Therefore, the object of the present invention is to solve the problems of the prior art, and in the vacuum RTM (Resin Transfer Molding) molding method for producing curved FRP, the FRP after molding is a product considering the change in thickness during molding. By adjusting the shape of the end of the preform in advance so as to obtain the design shape, it is possible to eliminate the trim processing of the FRP after molding and obtain an excellent quality FRP with no resin pool It is an object of the present invention to provide a method for producing a possible fiber reinforced plastic.

  In order to solve the above problems, the method for producing a fiber-reinforced plastic according to the present invention takes the following means.

  That is, a preform made of a reinforcing fiber base is placed in a mold having a curved surface or a bent shape, the preform is covered with a bag material, the inside is vacuum-sucked, and a resin is injected into the preform to be cured. In a method for producing a fiber reinforced plastic in which the thickness of the fiber reinforced plastic later is changed from the thickness of the preform, the reinforced fiber bases having different widths and / or lengths so that the end face of the fiber reinforced plastic has a desired shape Are formed in advance.

  In addition, the end face of the preform can be trimmed before resin injection so that the end face of the fiber reinforced plastic has a desired shape.

  The preform can be shaped in advance along the curved surface shape and fixed in shape. Moreover, the said preform can also be comprised with the reinforced fiber base material to which the resin material containing at least a thermoplastic resin was provided.

  Further, the end face of the preform can be trimmed in a state where the preform is compressed until the thickness of the preform becomes the same as the thickness of the desired fiber-reinforced plastic.

  The manufacturing method of the fiber reinforced plastic according to the present invention can also be applied to a structure in which the end surface of the fiber reinforced plastic obtained by the manufacturing method is substantially perpendicular to the mold surface.

  According to the method for producing a fiber reinforced plastic according to the present invention, it is possible to reduce waste of resin and waste by omitting the FRP trim processing, and there is no resin pool that becomes a defect in strength. An excellent quality fiber reinforced plastic (FRP) can be obtained.

It is sectional drawing of the shaping | molding apparatus for demonstrating the vacuum RTM shaping | molding method concerning this invention. It is sectional drawing of the preform for demonstrating the problem of a prior art. It is sectional drawing for demonstrating 1st Embodiment which concerns on the manufacturing method of this invention. It is a block diagram for demonstrating 2nd Embodiment which concerns on the manufacturing method of this invention. It is a block diagram for demonstrating 3rd Embodiment which concerns on the manufacturing method of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, this invention is not limited to the specific aspect described in drawing.

  FIG. 1 is a sectional view of a molding apparatus for explaining a vacuum RTM molding method according to the present invention. FIG. 2 is a cross-sectional view of a preform for explaining the problems of the prior art.

  As shown in FIG. 1, a preform 2 in which a plurality of layers of reinforcing fiber bases are stacked is placed on a mold 101 having a curved surface or a bent shape, the entire preform is covered with a bag material 3, sealed with a sealant 5, and ventilated. The inside of the bag material communicated with the vacuum pump 6 via the material 11, the suction line 8 and the vacuum trap 7 is depressurized, and the resin is obtained via the injection line 9 by the pressure difference between the inside of the bag material and the atmospheric pressure applied to the resin. 10 is injected into the preform 2. After the entire resin has been impregnated into the preform, the injection line is closed, excess resin in the preform is discharged from the suction line to a vacuum trap, and then the resin in the preform is cured and removed from the mold. To obtain FRP. In order to improve the diffusibility of the resin in the surface direction, the resin diffusion medium 4 may be disposed on the preform.

  The cavity in the vacuum RTM molding method corresponds to a gap formed by a mold and a bag material. Since the bag material is made of a flexible material such as a film, the volume and dimensions can change depending on the pressure state in the cavity. By injecting and discharging the resin to and from the preform, a volume change occurs in the preform, and the thickness of the preform changes during molding. That is, the vacuum RTM molding method is characterized in that the thickness of the preform is different from the thickness of the FRP after the resin is cured.

  Therefore, as shown in FIGS. 2A to 2C, in the vacuum RTM molding method using the mold 1 having a curved surface or a bent shape, the thickness T0 of the preform and the FRP of the product shape after resin curing In the case where the thickness T1 is different, there is a problem that the preform and the FRP have a difference in the required length 12 (hereinafter also referred to as a circumferential length) of the reinforcing fiber base disposed on the bag material side by the change in thickness. is there.

  That is, when the final thickness of the FRP is thinner than the preform, the necessary length of the reinforcing fiber base at the corner portion of the FRP becomes shorter than the preform as the resin cures. A surplus occurs in the peripheral length 12 of the reinforcing fiber base on the side. As a result, as shown in FIG. 2C, which shows a cross section of the FRP end portion, the end portion of the FRP is inclined with respect to the mold surface due to the difference in the circumferential length of the reinforcing fiber base material.

  Therefore, there is a problem that a portion where the reinforcing fiber is lacked at the end of the FRP, that is, the resin reservoir 13 is formed. When the resin reservoir 13 is generated in the FRP, it becomes a defect that the required strength and the like are not exhibited because there is no reinforcing fiber. Therefore, it is necessary to remove the resin reservoir 13 by trimming (cutting). In the case of performing trimming, it is necessary to cut a product that is longer than the exact size of the product and then cut it to the exact size. This increases waste of reinforcing fibers and resin, resulting in an increase in waste. In the case of a molded product that cannot be trimmed, a resin pool remains in the product, which may cause a quality problem that is a defect in strength.

  The mold having a curved surface or a bent shape according to the present invention is a circumferential length on the mold surface side and the bag material side when a plurality of reinforcing fiber bases of the same size are stacked on the mold. Therefore, it means that the end portion of the reinforcing fiber base layer has a shape (slope) that is not perpendicular to the mold surface. Specifically, it means a curved shape or a shape bent in at least two plane directions that intersect each other. The material of the mold is not particularly limited, and examples thereof include metal, plastic, and FRP.

  FIG. 3 is a cross-sectional view for explaining the first embodiment according to the manufacturing method of the present invention.

  In the present embodiment, as shown in FIGS. 2A to 2C, using a mold having a bent portion, a thickness T1 (T0> T1) after resin curing from a preform having a thickness T0. The FRP is molded. The desired product shape of the final FRP is preferably such that the FRP end has an end surface perpendicular to the mold surface.

  As shown in FIG. 3, the reinforcing fiber base material in which the length of the reinforcing fiber base material layer on the bag material side relative to the reference line in the direction perpendicular to the mold is arranged on the mold surface side at the end of the preform 2 A preform having a thickness T0 is formed by sequentially laminating a predetermined number of reinforcing fiber bases, the lengths of which are proportionally changed so as to be shorter than the layer length by (T0-T1), on the mold surface. 2 is formed. Here, the preform used in the present invention refers to a fiber structure composed of reinforcing fibers not impregnated with resin. Examples of reinforcing fibers include glass fibers, carbon fibers, and aramid fibers. Examples of the structure include a woven fabric laminate.

  Here, the circumferential length of the reinforcing fiber base changes either the width direction or the length direction of the reinforcing fiber base depending on the arrangement direction of the reinforcing fiber base forming the preform. In addition, when shaping a three-dimensional complex shape preform, it is important to change both the width direction and the length direction.

  As shown in FIG. 1, the entire preform 2 is covered with a bag material, sealed with a sealant, the inside of the bag material communicated with a vacuum pump via a suction line and a vacuum trap is decompressed, The resin is injected into the preform through the injection line due to the differential pressure of the pressure applied to the resin. Here, the bag material used in the present invention is not particularly limited as long as it is a flexible sheet, and examples thereof include organic synthetic films such as nylon and rubber-like elastic bodies such as silicone. After the entire resin is impregnated with the resin, the resin injection line is closed, and excess resin is discharged from the resin suction line. As the resin is discharged from the preform, the thickness of the preform decreases, and when the thickness T1 is smaller than the initial thickness T0, the resin is cured and demolded to obtain the FRP 21 having the thickness T1. The end portion of the FRP 21 is perpendicular to the mold surface and does not have resin richness. In addition, since it is not necessary to trim the FRP, waste of reinforcing fibers and resin, and waste can be reduced.

  FIG. 4 is a block diagram for explaining a second embodiment according to the manufacturing method of the present invention.

  In the present embodiment, a plurality of reinforcing fiber base materials are laminated on a mold 101 having a ¼ arc cross section with a radius R, and a preform 2 having a thickness T2 is preliminarily aligned with a substantially curved surface shape. Is shaped. The preform used in the present invention is preferably fixed in shape by a fixing means. The fixing means is not particularly limited as long as the reinforcing fiber base material is fixed. For example, there are means for sewing and fixing the base material with a fiber material, and means for bonding the base materials with a resin material. is there. Among these, it is preferable to fix the shape by heating and cooling using a reinforcing fiber base material provided with a resin material containing at least a thermoplastic resin. The final desired product shape of the FRP 22 has a thickness of T3 and the end surface of the FRP 22 is perpendicular to the mold surface.

  After shaping, the length of the reinforcing fiber outer layer on the bag material side with respect to the reference line in the direction perpendicular to the mold at the end of the preform is (1/2) × the length of the reinforcing fiber inner layer on the mold side The end face of the preform is cut obliquely into the cut shape 23 that is shortened by π × (T3−T2) using a metal cutter 31 or the like. Since it is not necessary to prepare reinforcing fiber bases having different sizes with respect to the first embodiment, a predetermined preform can be easily prepared.

  Also in the present embodiment, as in the first embodiment, as shown in FIG. 1, a resin is injected into the preform and cured, and the mold is removed to obtain FRP 22 having a thickness T3.

  FIG. 5 is a configuration diagram for explaining a third embodiment according to the manufacturing method of the present invention.

  In the present embodiment, as in the second embodiment, after the preform having the thickness T2 is shaped in advance along the substantially curved surface shape, the final product shape has a thickness T3, and , FRP whose end section is perpendicular to the mold surface is formed.

  In the present embodiment, after shaping, the FRP end surface after resin curing has a desired product shape in a state where the preform is compressed so that the thickness of the preform is the same as the thickness of the product shape. The end face is trimmed in advance at the preform stage. That is, a metal cutter 31 or the like is used so that the end face of the preform is perpendicular to the mold surface in a state where the preform is pressed and compressed on the mold so that the thickness of the preform is T3. Cutting.

  The pressurizing means is not particularly limited as long as it can compress the product to the thickness. For example, the preform is placed on the lower mold 102 having the same shape as the mold, and the compression cylinder is used from the bag surface side of the preform using the upper mold 103 having the same shape as the product shape until the thickness reaches T3. After compression using 32 or the like, the end of the preform may be trimmed. The shape of the preform can be cut with high precision by compressing with a mold from both sides. Further, it is more preferable to trim the preform with reference to the end portion of the mold from the viewpoint of stabilizing the cutting dimension.

  Also in the present embodiment, as in the first embodiment, as shown in FIG. 1, a resin is injected into the preform and cured to remove the mold, thereby obtaining an FRP having a thickness T3.

  In the above description, the FRP thickness after resin curing is described as being thinner than the preform thickness. However, the present invention is not limited to the above, and the thickness of the FRP after resin curing is increased. It can also be applied when the thickness is greater than the thickness of the reform. That is, the present invention can be applied to a case where a preform is impregnated with a large amount of resin to form an FRP having a low reinforcing fiber content.

Example 1
As shown in FIG. 4, this example uses a mold having a ¼ arc cross section with a radius R, from a preform with a thickness of 10.0 mm (T2) to a thickness of 8.6 mm (T3) after resin curing. ) FRP. The desired product shape of the FRP was such that the end of the FRP had an end surface perpendicular to the mold surface.

Unidirectional carbon fiber fabric (manufactured by Toray Industries, Inc., product name) in which a thermoplastic resin is dispersed and applied to a unidirectional fabric (weight per unit area 190 g / m ² ) of carbon fiber T800S (PAN-based carbon fiber, 24,000 filaments) manufactured by Toray Industries, Inc. CZ8433DP) was cut and 48 carbon fiber fabrics were sequentially laminated on a steel mold 101 having an arc cross section to prepare a reinforcing fiber preform 2 having a thickness of 10.0 mm.

  At the end of the preform 2, the length of the reinforcing fiber outer layer on the bag material side with respect to the reference line in the direction perpendicular to the mold is 2.2 mm longer than the length of the reinforcing fiber inner layer on the mold side (calculation formula: (1 / 2) × π × (T2-T3)) The cut end portion of the preform was cut obliquely into the cut shape 23 using a stainless steel cutter 31.

  As shown in FIG. 1, a reinforcing fiber preform 2 is placed on a steel mold 1 having an arc cross section, and a polypropylene mesh material (TSX-400P made by Tokyo Polymer) is placed as a resin diffusion medium 4. did. The reinforcing fiber preform 2 is covered with a bag material 3 (nylon film, 0.05 mm thickness), the periphery is sealed with a sealant 5 (manufactured by RICHMOND, SM5126), and communicated via a vacuum suction line 8 and a vacuum trap 7. The vacuum pump 6 was used to reduce the pressure inside the bag material 3 to 2 kPa or less in absolute pressure.

  Next, the entire molding apparatus was put into an oven set at 60 ° C. and heated until the preform temperature reached 60 ° C. Next, the resin injection line 9 was opened, and injection of the epoxy resin 10 was started. In this example, TR-A37 manufactured by Toray Industries, Inc. was used as an epoxy resin. After 30 minutes had elapsed from the resin injection, the resin injection line was closed, and excess resin was discharged from the resin suction line. As the resin was discharged from the preform 2, the thickness of the preform 2 decreased, and when the thickness became 8.6 mm, the resin suction line was closed and the oven set temperature was raised to 120 ° C. for 4 hours. The resin was cured by holding. Finally, it was cooled to room temperature and the FRP was removed from the mold 1.

  As a result of confirming the appearance of the obtained FRP, the end shape of the FRP was perpendicular to the mold surface. Further, there was no resin rich at the end due to the lack of reinforcing fibers, and an FRP having a desired quality could be obtained.

(Example 2)
In this example, in the same manner as in Example 1, using a mold having a ¼ arc cross section with radius R, a thickness of 8.6 mm after resin curing from a preform with a thickness of 10.0 mm (T2) ( The FRP of T3) was to be molded. The desired product shape of the FRP was such that the end of the FRP had an end surface perpendicular to the mold surface.

As shown in FIG. 5, a carbon fiber fabric (Toray Industries, Inc.) obtained by dispersing and imparting a thermoplastic resin to a unidirectional fabric (weight per unit of 190 g / m ² ) of carbon fiber T800S (PAN-based carbon fiber, 24,000 filaments) manufactured by Toray Industries, Inc. Manufactured, product name CZ8433DP), and 48 carbon fiber fabrics are sequentially laminated on a steel lower mold 102 having an arc cross section of the same shape as the molding die 101 shown in FIG. A reinforcing fiber preform 2 having a thickness of 10.0 mm was prepared.

  An upper mold 103 having the same shape as the product shape is placed on the preform, and the lower mold is pressurized using the compressed air compression cylinder 32 until the preform thickness T3 becomes 8.6 mm. 2 was compressed (the upper die and the compression cylinder were fixed with a rigid frame. The illustration was omitted). The preform was trimmed by using a steel push cutter 31 so that the end face of the preform was perpendicular to the lower mold surface with the end of the upper mold 103 as a reference. At the time of pressurization, the lower mold was heated to 80 ° C., cooled to room temperature, and the carbon fiber fabrics were bonded to each other with the thermoplastic resin to fix the shape of the preform.

  As shown in FIG. 1, the preform 2 was placed on a molding die 101, and the resin was injected and cured in the same manner as in Example 1. As a result of confirming the appearance of the obtained FRP, the end shape of the FRP was perpendicular to the mold surface. Further, there was no resin rich at the end due to the lack of reinforcing fibers, and an FRP having a desired quality could be obtained.

  The present invention can be applied to any reinforcing fiber plastic manufacturing method, and is particularly suitable for manufacturing a complicated shape having a curved surface or a bent shape, or a member having a large thickness, for example, a vehicle, a ship, an aircraft, The present invention can be applied to a wide range of FRP manufacturing methods used in various fields such as industrial uses such as building members or sports uses.

1: Mold 2: Preform 3: Bag material 4: Resin diffusion medium 5: Sealant 6: Vacuum pump 7: Vacuum trap 8: Suction line 9: Injection line 10: Resin 11: Ventilation material 12: Arranged on the bag material side Required length of the reinforced fiber base material 13: Resin reservoir 21: FRP with thickness T1
22: FRP with thickness T3
23: Cut shape 31: Cutter 32: Compression cylinder 101: Mold 102: Lower mold 103: Upper mold

Claims (6)

A preform made of a reinforcing fiber base is placed in a mold having a curved surface or a bent shape, the preform is covered with a bag material, the inside is vacuum-sucked, and a resin is injected into the preform to be cured. In a method for producing a fiber reinforced plastic in which the thickness of the fiber reinforced plastic is changed from the thickness of the preform, the reinforcing fiber bases having different widths and / or lengths are laminated so that the end surface of the fiber reinforced plastic has a desired shape. Then, a preform is formed in advance, and a method for producing a fiber reinforced plastic is provided. A preform made of a reinforcing fiber base is placed in a mold having a curved surface or a bent shape, the preform is covered with a bag material, the inside is vacuum-sucked, and a resin is injected into the preform to be cured. In the fiber reinforced plastic manufacturing method in which the thickness of the fiber reinforced plastic is changed from the thickness of the preform, the end surface of the preform is trimmed before the resin injection so that the end surface of the fiber reinforced plastic has a desired shape. A method for producing fiber-reinforced plastic. The method for producing a fiber-reinforced plastic according to claim 2, wherein the preform is shaped in advance along a curved surface shape and the shape is fixed. The method for producing a fiber reinforced plastic according to claim 3, wherein the preform is composed of a reinforced fiber base material to which a resin material containing at least a thermoplastic resin is applied. The end face of the preform is trimmed in a state in which the preform is compressed until the thickness of the preform is equal to the thickness of a desired fiber-reinforced plastic. The manufacturing method of the fiber reinforced plastic of description. A method for producing a fiber reinforced plastic, wherein an end face of the fiber reinforced plastic obtained by the production method according to claim 1 is substantially perpendicular to the mold surface.

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