JP2012206391A - Method of molding fiber-reinforced plastic - Google Patents

Abstract

An object of the present invention is to provide a method for producing a fiber-reinforced plastic that is free from defects such as wrinkles on the outer surface and excellent in appearance in molding using a core.
A core 4 having a desired shape in which a large number of particles 4a having fluidity are accommodated in a flexible bag 4b is formed, and the core 4 is disposed between fabrics 3 made of fibers. When the resin mold is placed in the molding molds 1 and 2 and the resin mold is formed by the molding molds 1 and 2, a part of the outer peripheral surface of the core 4 is pressed by pressing means. And forming the fiber reinforced plastic by deforming and increasing the internal pressure in the core 4.
[Selection] Figure 1

Description

  The present invention relates to a molding method for producing a molded body of fiber reinforced plastics (FRP) by performing a resin transfer molding method using a core on a fabric composed of fibers.

  As a molded body of fiber reinforced plastic having a closed cross section, it is widely used from large molded bodies such as aircraft fuselage and wings to small molded bodies such as bicycle frames, tennis rackets, fishing rods and golf shafts. . Further, as a fiber-reinforced plastic molded body having an open cross section, it is widely used for helmets and the like.

  As a core for forming a closed cross-section, a core or the like in which a foam or a powder is wrapped with a packaging film and formed into a predetermined shape is used. As a core in which powder particles are formed in a desired shape, a method for manufacturing a fiber reinforced plastic (see Patent Document 1) has been proposed.

  The invention described in Patent Document 1 will be described as a conventional example 1 of the present invention with reference to FIG.

  FIG. 5 shows a manufacturing process of a molded product having a hollow portion which is a kind of closed section by the molding die 108. That is, a preform 107 formed by winding reinforcing fibers around the core 104 is placed in the cavity 109 of the mold 108 together with the core 104. Here, a connection tool (not shown) that can be connected to an air supply passage (not shown) provided in the mold 108 is provided at the mouth of the film bag 105.

  When the preform 107 and the core 104 are arranged in the cavity 109, the mouth of the sealed film bag 105 is opened, and a connection tool (not shown) is provided in the mold 108 in the film bag 105. They are connected by being attached to an air supply passage (not shown). The air supply passage (not shown) is connected to an air compressor (not shown), and the air discharged from the air compressor is supplied into the film bag 105 through the air supply passage.

  After the preform 107 is placed in the cavity 109 together with the core 104, the resin injection device 110 and the injection hole 111 are provided by a three-way valve 113 provided in the injection pipe 112 that connects the resin injection device 110 and the injection hole 111. And disconnect.

  Next, the decompression pump 114 is driven in a state where the decompression pump 114 and the discharge hole 115 are connected by the three-way valve 117 provided in the suction pipe 116 that connects the decompression pump 114 and the discharge hole 115, thereby The inside of the cavity 109 is depressurized to a state close to vacuum through 115.

  Subsequently, a resin impregnation step of connecting the resin injection device 110 and the injection hole 111 and injecting the resin injected from the resin injection device 110 into the cavity 109 from the injection port 111a in a state where the inside of the cavity 109 is decompressed is performed. Done. Note that a curing agent is added to the resin impregnated in the preform 107.

  In the resin impregnation step, the resin injection device 110 gradually increases the resin injection pressure at a constant flow rate, and finally sends out the resin at a high injection pressure (for example, 5 MPa). Here, the injection pressure means the pressure of the resin delivered from the resin injection device 110 and corresponds to the detected pressure of the pressure gauge 118.

  When the resin is injected into the cavity 109 at a high pressure, the resin is impregnated so as to reach the entire preform 7. At this time, since the core 104 is hardened with the particles 106 filled in the film bag 105, the core 104 is maintained in a predetermined shape without being deformed even when a high pressure is applied from the outside during resin injection. .

  The resin injection device 110 stops the operation of the resin injection device 110 and the decompression pump 114 after injecting the resin for a predetermined time. In addition, the three-way valves 113 and 117 are opened to the atmosphere, and the resin injection is finished.

  Then, a resin curing step is performed to cure the resin. In the resin curing step, after the injection of the resin is finished, heating of the resin is started by a heating means (not shown) provided in the mold 108, and an air supply means (not shown) (for example, an air compressor) is started. ) To pressurize the film bag 105 by supplying air into the film bag 105.

  When air is supplied into the film bag 105, the air passes through the particles 106 and spreads uniformly into the film bag 105 as indicated by the dotted arrows in FIG. 5, and the film bag 105 has a preset pressure. The resin is cured and the pressure in the film bag 105 is applied in parallel. And the film bag 105 presses the inner peripheral surface of the preform 107 uniformly by the outer peripheral surface.

  In addition, when pressurizing the inside of the film bag 105, an experiment is performed in advance to obtain a pressure that balances with the pressure generated by the curing / solidification shrinkage of the resin used, and the inside of the film bag 105 is pressurized to the determined pressure. When the curing and solidification of the resin is in progress, the pressure generated by the curing / solidification shrinkage of the resin balances with the pressure in the film bag 105, and the curing / solidification shrinkage of the resin is suppressed. Can suppress or disperse sink marks. Then, pressure is continuously applied to the inner peripheral surface of the preform 107 by the film bag 105 until the curing of the resin is completed. When the curing of the resin is completed, the heating of the resin by a heating unit (not shown) is finished and the film bag 105 is finished. The air supply is finished.

  In the demolding step, the mold 108 is opened, a connector (not shown) provided on the film bag 105 is removed from an air supply passage (not shown), and the FRP product is taken out from the mold 108 together with the core 104. Thereafter, in the core removal step, the mouth of the film bag 105 is opened to release air contained in the film bag 105, and then the particles contained in the film bag 105 are taken out through the mouth to remove the film. Squeeze the bag 105. Then, by removing the film bag 105 from the FRP product, an FRP product in which the core 104 is removed is manufactured.

JP 2008-155383 A

  In the invention of Patent Document 1, a resin is injected into a mold, a preform is impregnated with resin, fluid or particles are supplied to the core, the resin is cured with internal pressure applied, and demolded to produce an FRP product. is doing.

  When impregnating a fiber or fiber product with a resin, the core is composed of particles without deforming the core due to the resin injection pressure, and the particles are bonded with a water-soluble binder or a decomposable adhesive. Is illustrated. In this case, high accuracy is required for the outer shape of the core, that is, the inner shape is offset from the product outer shape by the thickness of the preform, and the shape becomes the core shape. In the case of a complex shape, especially in the case of a complicated shape, if a region not impregnated with the resin is created due to the difference in the flow rate of the resin, it remains as a defect even if the inside of the core film back is pressurized in the curing process.

In order to achieve the above object, in the method for molding a fiber reinforced plastic of the present invention, forming a core having a desired shape in which a large number of fluid particles are accommodated in a flexible bag,
Placing the core between the fabrics made of fibers and placing the core inside the molding die;
When performing the resin transfer molding using the molding die, it is most important to include a pressing means to press and deform a part of the outer peripheral surface of the core to increase the internal pressure in the core. It is a feature.

  In this invention, the core formed in the desired shape which accommodated many granule made into the structure which has high fluidity | liquidity in the flexible bag body is used. In addition, when resin transfer molding is performed by a molding die, a depression is formed on the outer peripheral surface of the core by pressing a part of the outer peripheral surface of the core through the fabric constituted by the fibers or without using the fabric. The internal pressure by the core is forcibly increased. And by increasing the internal pressure by the core, slip is generated between the particles constituting the core, and the core is deformed.

  By deforming the core, even if the distance between the fabric enclosing the core and the core is increased, the distance can be reduced by deformation of the core. In particular, even when the gap between the corner of the molding surface of the molding die and the fabric is wide, the fabric can be moved in the direction of narrowing the gap by deformation of the core.

  The core can be deformed because a large number of granules having a high fluidity are accommodated in the flexible bag, but if such a configuration is adopted, the outer periphery of the core is pressed to the outer periphery. Even if the core is deformed by forming a recess in the surface, the internal pressure in the core is not usually the same pressure in all parts as in the case of using liquid or gas. That is, even if pressure is applied to the particles, a pressure smaller than the pressure at the portion where the pressure is applied is generated at the other portion. And when the applied pressure exceeds a certain value, slip occurs between the particles.

  Therefore, when the outer peripheral surface of the core is pressed, the outer peripheral surface of the core away from this portion even if the internal pressure there is greatly increased in the portion where the depression is formed in the outer peripheral surface of the core by pressing. The pressure increase at the site on the side is lower than the internal pressure at the site where the depression is formed.

  In particular, the pressure transferability within the core and the fluidity of the particles are affected by the roughness of the particle surface and the particle diameter of the particles. When particles having a uniform particle diameter are used, the particles are packed most closely in the core, the fluidity of the particles is hindered, and the pressure transferability is impaired. Therefore, considering the particle size distribution and particle surface roughness distribution in the core, or using a combination of particles with different particle sizes, the fluidity of the particles in the core And pressure transmission improves.

  Even in a portion in the core away from the portion where the depression is formed by the pressing, the outer peripheral surface area of the core is deformed by the sliding of the granules. Thereby, the fabric can be pressed along the molding surface of the molding die.

  The core is preferably formed by vacuum-packaging a large number of particles with a packaging film made of a material that can be extended and expanded because it can be easily formed and can be formed into an accurate shape. In this case, when the internal pressure of the core is increased, each granule moves by sliding in the front-rear and left-right directions, but the packaging film wrapping each granule is The deformation of the outer shape of the core accompanying the movement of the particles can be allowed.

  Temporarily, when the pressure of the granule rises due to the clamping of the molding die or the press forming the depression, the packaging film does not have the strength to hold the granule against the pressure. It may break. If the gap between the molding dies is smaller than the diameter of the particles, no leakage from the molding dies will occur unless the particles are crushed.

  As a structure which presses a part of outer peripheral surface of a core, it can be set as the structure using the rod which can be freely projected and retracted in the molding surface of a molding die. As a configuration using a rod that can freely move in and out of the molding surface of the molding die, for example, a configuration using a piston rod as the rod can be used, and a pressing portion can be installed at a plurality of sites.

  In the present invention, when the outer peripheral surface of the core is pressed, a part of the outer peripheral surface of the core can be pressed through the fabric or without the fabric. When pressing through the fabric at a substantially planar portion, a recess is formed in the fabric. When pressing through the fabric at the convex part, the fabric will be flat. Except for the depressions and flat portions, which are the pressing parts, and the pressing part, a discharge hole for discharging the particles constituting the core from the molded product can be provided.

  In addition, when pressing a part of the outer peripheral surface of the core without going through the fabric, a hole corresponding to a pressing portion such as a rod is made in the fabric, and the core is directly pressed. The packaging film can be broken from the hole position, and the particles can be discharged. The packaging film can be removed from the packaging film in contact with the particles by performing a release treatment such as application of a release material, or double packaging.

It is a schematic diagram which shows the time of pressure molding. Example 1 It is a schematic diagram which shows the internal structure of a fabric and a core. Example 1 It is a schematic diagram which shows each step which manufactures the molded article which has a hollow part. Example 1 It is a schematic diagram which shows the time of other pressure molding. (Example 2) It is a schematic block diagram explaining the resin impregnation process and the resin hardening process. (Conventional example 1)

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. As a method for molding fiber reinforced plastic according to the present invention, the core can be deformed during pressure molding by the molding die, even if the molding die, the core and the like described below are not used. The present invention can be suitably applied to these configurations as long as they can be configured.

  As shown in FIG. 1, a preform 1 in which a fabric 3 containing a core 4 is shaped into substantially the same shape as the inner peripheral surface of a molding die 15, and a lower mold 1 of the molding die 15 heated in advance. It is placed in the recess 1a formed in the above.

  The fabric 3 can be composed of a non-woven fabric or the like that is uniaxial or multiaxial from fibers such as carbon fiber, glass fiber, aramid fiber, or silicon carbide fiber, and further has a random fiber direction. In the illustrated example, the cross-sectional shape of the fabric 3 is formed in an annular shape, and the core 4 is interposed inside. For example, the fabric 3 can be configured as in the illustrated example by forming the core 4 so as to be wrapped between two sheet-like fabrics.

  Then, after injecting a thermosetting resin from the injection hole 16 of the molding die and impregnating the fabric 3 with the resin, the resin is heat-cured in the molding die, and a fiber reinforced plastic (FRP) having a desired shape. Can be produced.

  As the thermosetting resin impregnated into the fiber, epoxy resin, urea resin, vinyl ester resin, unsaturated polyester, polyurethane, phenol resin, or the like can be used.

  The core 4 is formed in a desired outer shape by wrapping the particles 4a with a packaging film 4b and performing vacuum pack packaging. As the granules 4a constituting the core 4, ceramics such as alumina and zirconia, glass, hard heat-resistant resin, metal, foundry sand and the like can be used as the granules. As the packaging film 4b used for maintaining the shape of the core 4, a nylon film, a polyethylene film, a fluororesin film, silicon rubber, or the like can be used. When zirconia or quartz is used as the particles 4a, these materials have a low thermal conductivity, and therefore are suitable materials for the particles 4a of the core 4.

  The lower mold 1 is provided with a cylinder 5 provided with a piston rod 5a that can be moved into and out of the cavity of the molding die 15. In FIG. 1, the piping for supplying and discharging the working fluid to and from the pressure chamber of the cylinder 5 for sliding the piston rod 5a is omitted.

  First, the upper mold 2 and the lower mold 1 are moved in directions close to each other, whereby the mold is clamped and the fabric 3 placed in the recess 1a of the lower mold 1 can be pressurized. When the resin is injected, the pressure is not high, and the distance between the mold and the core is widened so that the resin can be injected at a relatively low pressure. After filling the resin, the pressure is increased by a piston rod or by further clamping. After resin filling, pressurization is performed by at least one of a piston rod and mold clamping. In the case where mold pressing after resin filling is not performed, the mold clamping machine may have a mold opening / closing mechanism, and a high-pressure press is not required.

  At this time, by projecting the piston rod 5a into the cavity of the molding die 15, a part of the outer peripheral surface of the core 4 interposed in the fabric 3 is pressed. By this pressing, as shown in FIG. 2 in which the circled portion A in FIG. 1 is enlarged, the fluidity of the particles 4a is improved by the particle structure having combinations with different particle diameters, and the particles in the core 4 are improved. The body 4a slips.

  In particular, at the four corners on the inner surface of the fabric 3 where voids and voids are likely to occur, it is possible to avoid bending, wrinkles, voids and voids in the area along the inner surface of the vertical part formed along the wall surface of the recess 1a. The child 4 can be deformed and brought into close contact with the inner surface of the fabric 3, and a molded product with high dimensional accuracy can be obtained.

  By deforming the core 4, even if a gap or void is formed between the fabric 3 impregnated with the resin enclosing the core 4 and the core 4 before mold clamping, the gap or void is formed. The air that has been crushed by a high internal pressure by the core is discharged from the molding die 15 into the atmosphere through the fabric 3 impregnated with the resin. The passage formed when the air passes through the fabric 3 impregnated with the resin is naturally blocked by the fabric 3 impregnated with the resin after the passage of air.

  In addition, in the corner portion of the molding die 15, even when there are voids or voids between the molding die 15 and the fabric 3 impregnated with the resin, the core whose outer peripheral surface shape is widened By pressing from 4, the fabric 3 moves to the gap or void side. The air forming the voids and voids can be crushed by a high internal pressure or can be pushed out from the molding die 15 into the atmosphere.

  In each of the drawings used in the description of the examples, the thickness of the packaging film 4b is shown thick in an exaggerated state in order to easily explain the packaging film 4b. Actually, the packaging film 4b can be formed in a thin film shape having a thickness of 1 mm or less. Here, although the structure which shape | molds a square pipe-shaped molded product is demonstrated, as a molded product, it can comprise in the other shape which has a closed cross section.

  Examples of the shape close to the closed cross section include a C-shaped cross section. For example, when forming a molded product having a C-shaped cross-sectional shape, a configuration in which a part of the core is in direct contact with the molding surface of the upper mold 2 or the lower mold 1 can be employed. Then, by covering the periphery of the core not in contact with the molding surface with the fabric 3, a molded product having a C-shaped cross-sectional shape can be molded. For this reason, as a closed cross section in the present invention, in addition to a shape such as a square pipe shape, for example, a C-shaped cross section is also included in the closed cross section in the present invention.

  As shown in FIG. 1, the concave portion 6 is formed on the outer peripheral surface of the fabric 3 by pressing a part of the outer peripheral surface of the core 4 with the piston rod 5 a. When the outer peripheral surface of the core 4 is pressed by the piston rod 5a, the volume of the piston rod 5a that has entered the volume of the granule 4a is forcibly added as the volume in the core 4. As a result, the internal pressure in the core 4 can be increased.

  As the internal pressure of the core 4 increases, each particle 4a slips between the particles and moves in the front-rear and left-right directions. However, since the packaging film 4b wrapping each grain 4a is made of a material that can be vacuum-packed, the packaging film 4b extends without substantially restricting the movement of each grain 4a. Can be deployed.

  Thus, since the internal pressure of the core 4 can be increased and the slip between the granules 4a can be caused, the core 4 can be deformed. As shown in FIG. 2, the core 4 and the fabric 3 are deformed. Gaps and voids can be eliminated.

In addition, the deformation of the core 4 is likely to generate voids and voids at a site where the pressure between the fabric 3 impregnated with the resin is low and the thickness of the fabric 3 impregnated with the resin while eliminating the voids and voids. Can be maintained at a predetermined thickness.
Thus, the fabric 3 having a predetermined thickness and impregnating the resin in a shape having a desired outer peripheral surface shape can be pressure-molded.

  FIG. 3 (a) shows a state where the semi-molded product 10 a that has been subjected to pressure molding by the molding die 15 is taken out from the molding die 15. A recess 6 is formed in a portion of the fabric 3 pressed by the piston rod 5a.

As shown in FIG. 3 (b), when a hole for discharging is formed in the recess 6a, air flows between the particles 4a constituting the core 4 from this hole, and the coupling state between the particles 4a is Collapse. Then, the particles 4a in which the combined state is broken can be discharged to the outside from the discharge hole formed in the recess 6a. And as shown in FIG.3 (c), the molded article 10 which has the hollow part 10b can be completed.
If the packaging film 4b in which the granules 4a are vacuum-packed is made of a material that has good releasability with respect to the molded product 10, or if the packaging film 4b is doubled, the packaging is in contact with the granules 4a. The film 4b can also be removed from the molded product 10.

  As described above, since the resin 3 impregnated with the resin 3 can be pressure-molded without any voids or voids between the core 4 and the fabric 3, the molded product 10 is desired to have no bending or wrinkles. It can be manufactured as a product having a desired outer peripheral shape with a thick wall. Further, even when the internal pressure in the core 4 is low when the molding die is closed, the internal pressure in the core 4 can be increased by the pressing force applied from the piston rod 5a. Can be manufactured into a product having a desired thickness and a desired outer peripheral surface shape.

Example 1 will be specifically described. As shown in FIG. 1, a core 4 was produced in which zirconia particles (mixed with a diameter of 1 mm and 3 mm) were vacuum packed with a nylon film. Carbon fiber plain fabric 3 (TR3110 manufactured by Mitsubishi Rayon Co., Ltd.) was encased in 5 plies and the core 4 was encapsulated, and preformed into a shape substantially the same as the shape of the inner peripheral surface of the molding die 15. After placing the preform in the recess 1a formed in the lower mold 1 of the molding die 15 at 80 ° C, the upper mold 2 and the lower mold 1 are completely clamped, and then injected with epoxy resin and filled The piston rod 5a pressed a part of the outer peripheral surface of the core 4 at 3 MPa. After 120 minutes, the mold was opened and the molded product was taken out. A hollow for discharging is formed in the recess 6 (FIG. 3 (a)) formed by pressing the piston rod, and the particles 4a are discharged to the outside through the hole for discharging (FIG. 3 (b)) to obtain a hollow molded product. (FIG. 3C). This molded product had high dimensional accuracy and was excellent in appearance without defects such as wrinkles on the outer surface.
<Example 2>

  The configuration of the second embodiment according to the present invention will be described with reference to FIG. In the first embodiment, the configuration using the piston rod 5a to press the core 4 has been described. However, in the second embodiment, the piston rod 5a is not used to press the core 4. Other configurations are the same as those in the first embodiment, and the same components are denoted by the same reference numerals as those used in the first embodiment, and the description of the members is omitted.

  As shown in FIG. 4, the preformed fabric 3 is stored in the recess 1 a of the lower mold 1. As shown in FIG. 3C, the core 4 is disposed in the fabric 3 in order to manufacture the molded product 10 having the hollow portion 10b.

  After the resin injection, the upper mold 2 and the lower mold 1 are pressure-molded by a mold clamping machine capable of generating high pressure. By being clamped, the fluidity of the granules 4a is improved by the particle structure having a combination with different particle diameters, and the core 4 is deformed to form a gap between the core 4 and the fabric 3 impregnated with the resin. And voids can be prevented. In addition, it is possible to prevent the formation of voids and voids that are likely to occur between the molding surface of the molding die 15 and the fabric 3 impregnated with the resin.

  A present Example is shown concretely. As shown in FIG. 4, molding was performed in the same manner as in Example 1 except that the piston rod 5 a was not used and pressing was performed by the upper mold 2. The mold was opened, the molded product was taken out, a discharge hole was opened on the side of the molded product, and the granules 4a were discharged to the outside through the discharge hole to obtain a hollow molded product. This molded product had no defects such as wrinkles on the outer surface and was excellent in appearance.

  The present invention can be suitably applied in molding using a core.

1 ... Lower mold 2 ... Upper mold 3 ... Fabric 4 ... Core,
4a ... Granules,
4b ... packaging film,
5a ... piston rod,
15 ... Mold for molding,
16 ... Injection hole 104 ... Core 105 ... Film bag 106 as a bag member ... Particle 107 ... Preform 108 ... Mold 109 ... Cavity 110 ... Resin injection Device 111 ... Injection hole 111a ... Injection port 112 ... Injection tube 113 ... Three-way valve 114 ... Decompression pump 115 ... Discharge port 116 ... Suction tube 117 ... Three-way valve 118 ... Pressure gauge

Claims (5)

Forming a core having a desired shape in which a large number of particles having fluidity are accommodated in a flexible bag;
Placing the core between the fabrics made of fibers and placing the core inside the molding die;
When performing resin transfer molding with the molding die, with a pressing means, press and deform a part of the outer peripheral surface of the core to increase the internal pressure in the core,
A method for forming a fiber reinforced plastic including:   The method for molding a fiber reinforced plastic according to claim 1, wherein the flexible bag is a packaging film, and the particles are vacuum packed with the packaging film to form the core.   The method for molding a fiber-reinforced plastic according to claim 1 or 2, wherein a granule having a nonuniform particle diameter is used as the granule.   The method for molding a fiber-reinforced plastic according to any one of claims 1 to 3, wherein clamping is performed after resin injection.   In the molded product molded after the compression molding by the molding die, including using a portion that presses a part of the outer peripheral surface of the core as a discharge hole for discharging the granules from the molded product. Item 5. A method for molding a fiber-reinforced plastic according to any one of Items 1 to 4.