JP4487239B2 - Method for manufacturing FRP structure - Google Patents

Description

  The present invention relates to a method for manufacturing an FRP (Fiber Reinfoced Plastics) structure, and in particular, in order to prevent deterioration in strength at the end of a molded product, the reinforcing fiber base material is easily distributed to every corner of the molded product. In particular, the present invention relates to a method for manufacturing an FRP structure suitable for manufacturing an FRP molded product that maintains the strength of the end of a thin plate (thickness of about 0.5 to 5 mm).

  FRP, especially CFRP (carbon fiber reinforced resin) is used in various fields as a composite material having a light weight and high mechanical properties. As one of the FRP molding methods, there is known an RTM molding method (resin transfer molding) in which a reinforcing fiber base is placed on a mold, and after closing the mold, the inside of the mold is depressurized to inject a liquid resin and heat cure. ing.

  The RTM molding method is one of the most suitable methods for realizing light weight, high mechanical properties, and complex shapes, which are the characteristics of FRP, particularly CFRP. However, removal of unnecessary parts such as deburring after molding requires NC machining, which leads to an increase in man-hours and processes. In particular, CFRP is one of the processes to be omitted because the fibers are hard and the tool wears quickly. In order to omit this work, various proposals regarding shaping of the reinforcing fiber base have been made to obtain the shape of the reinforcing fiber base as close as possible to the molded shape.

For example, it has already been proposed to shape the reinforcing fiber base material to some extent in advance by placing it between the upper and lower shaping dies before being placed in the molding die (for example, Patent Document 1). Further, if a thermoplastic resin material is applied to a plurality of reinforced fiber base materials and heat-shaped by the above-described shaping mold, it is possible to maintain a more reliable shape (for example, Patent Document 2). In addition, a reference line is placed on the mold, and markings along the weaving yarn are applied to the position of the reinforcing fiber base that matches the reference line. (For example, Patent Document 3).
JP 2003-305719 A JP 2003-80607 A JP 2003-127157 A

  However, in the conventional method as described above, if NC machining or the like is to be omitted, it is necessary to make the reinforcing fiber base smaller than a predetermined molding shape so as not to protrude from the molding shape. For example, as shown in FIGS. 1 and 2, when a thin plate-like (thickness of about 0.5 to 3 mm) fiber reinforced resin molded article 101 such as a cowl of a motorcycle is molded by an RTM molding method, This leads to the presence of the resin-rich portion 103 that is not filled with the fiber reinforced base material 102, and due to the nature of the end portion, it is easily affected by impact such as bumping, and “cracking” of the portion with reduced strength often becomes a problem. .

  In order to obtain the desired strength up to the end of the molded article of the reinforcing fiber base, it is necessary that the reinforcing fiber base is spread to every corner of the end. Therefore, as shown in FIG. 3, in order to spread the reinforcing fiber base material 102 to every corner of the molded product, the shape is strictly adjusted in advance using a shaping mold before being arranged in the lower mold. Although the method was examined, since the size of the woven fabric was shifted greatly, the required dimensional accuracy (for example, about ± 2 mm) was difficult to obtain. Furthermore, it is possible to cut the edge with scissors etc. on the mold and adjust it precisely, but at the same time the work time becomes long and at the same time, there will be a difference in quality due to the skill level of the worker and the ability Occurs.

  Therefore, an object of the present invention relates to the production of a reinforced fiber base material that matches the shape of the mold in order to prevent the strength of the end of the molded product from being lowered, which is a problem of the conventional FRP molding method. Another object of the present invention is to provide a method for producing an FRP structure capable of forming an FRP structure having a good quality without taking time and effort.

In order to solve the above-mentioned problem, a method for manufacturing an FRP structure according to the present invention is a method for manufacturing an FRP structure in which a reinforcing fiber substrate is disposed in a mold, and after being injected with a resin, the resin is cured and molded. As the reinforcing fiber base, a main reinforcing fiber base smaller than a molded shape constituted by a woven sheet and a secondary reinforcing fiber base constituted by short fibers arranged around the main reinforcing fiber base are bonded and integrated. It consists of the method characterized by using a fiber base material .

In the above method SL, the main reinforcing fiber base material may by forming moderately reduced to molded shape, pre-processing and shaping can be performed very easily. Then, by arranging a sub-reinforced fiber base composed of short fibers around it and bonding and integrating it with, for example, a thermoplastic resin, it is possible to reliably arrange the reinforcing fibers to every corner of the molded shape. This thermoplastic resin does not constitute a matrix resin for FRP, but is merely used for adhesion and integration of the sub-reinforcing fiber base material, so that it is substantially unrelated to the mechanical properties of the molded FRP structure. It is. As described above, the reinforcing fibers are easily arranged to the every corner, so that an FRP structure having a good quality is formed to the end.

  According to the method for manufacturing an FRP structure according to the present invention, the reinforcing fiber base does not need to be subjected to precision processing such as NC processing in advance, and may be performed by extremely simple processing or shaping that does not require accuracy, Work is easy and there is no difference in quality between workers. Since the reinforcing fibers can be surely arranged to every corner of the molded product, it is possible to easily and inexpensively form an FRP structure of good quality up to the end.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
In the present invention, FRP refers to a resin reinforced with reinforcing fibers. Examples of reinforcing fibers include inorganic fibers such as carbon fibers, glass fibers, and metal fibers, or aramid fibers, polyethylene fibers, and polyamide fibers. Reinforcing fibers made of organic fibers can be mentioned. Examples of the FRP matrix resin include thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, and phenol resins. Furthermore, polyamide resins, polyolefin resins, dicyclopentadiene resins, polyurethane resins, Thermoplastic resins such as polypropylene resin can also be used.

  The resin used in the RTM molding method according to the present invention is preferably a thermosetting resin or a monomer for RIM (Reaction Injection Molding) that forms a thermoplastic resin that has a low viscosity and can be easily impregnated into a reinforcing fiber. Among them, modified epoxy resins, nylon resins, and dicyclopentadiene resins blended with an epoxy resin or a thermoplastic resin or a rubber component are more suitable from the viewpoint of reducing thermal shrinkage of the FRP structure and suppressing the occurrence of cracks.

  The reinforcing fiber substrate used in the present invention refers to a substrate made of reinforcing fibers not impregnated with resin, for example, the reinforcing fiber fabric, chopped fiber, mat, knit material, and these and insert parts. Can be used depending on the application. Examples of the insert parts include metal plates such as steel and aluminum, metals for joining such as metal columns, metal bolts, nuts, and hinges, aluminum honeycomb cores, polyurethane, polystyrene, polyimide, vinyl chloride, phenol, acrylic, and the like. Foam materials, rubber materials, wood materials, etc. composed of the above polymer materials are mainly used, and insert parts intended for joining such as nails and screws can be raised, with a hollow structure for the purpose of weight reduction Insert parts that are used for the purpose of damping vibration are often used.

  Moreover, the shaping | molding die used by this invention consists of a shaping die which consists of an upper mold | type and a lower mold | type, for example, for example, an upper mold | type is attached to a mold raising / lowering apparatus. Reinforcing fiber base material is installed in the lower mold. This reinforcing fiber base is prepared by a shaping mold for the purpose of shaping the reinforcing fiber base into a product shape so that it can be easily accommodated in the mold in advance. Examples of the material of the mold include FRP, cast steel, structural carbon steel, aluminum alloy, zinc alloy, nickel electroforming, and copper electroforming. For mass production, structural carbon steel is suitable in terms of rigidity, heat resistance, and workability.

  FIG. 4 shows a molding system for carrying out a method for manufacturing an FRP structure according to an embodiment of the present invention. In FIG. 4, reference numeral 2 denotes a molding die as a molding die having an upper die and a lower die, and the upper die is attached to the die lifting device 1. The mold lifting / lowering apparatus 1 has a hydraulic unit 9 including a hydraulic pump 10 and a hydraulic cylinder 11, and the operation and pressurization of the upper mold are controlled by hydraulic pressure.

  The mold 2 is connected to a resin injection channel 13 connected to the resin injection port 8a and a discharge channel 14 connected to the discharge port 8b. The resin injection channel 13 and the discharge channel 14 are connected to the injection port 8a and the discharge port 8b via an injection valve 22a and a discharge valve 22b, respectively. The opening / closing operation of the injection valve 22a and the discharge valve 22b and the operation timing thereof are performed based on commands from the control device 22c. A resin injection device 3 is connected to the resin injection flow path 13. The resin injection device 3 stores the main agent and the curing agent in the main agent tank 5 and the curing agent tank 6, respectively, and each tank has a mechanism capable of heating and can be degassed by the vacuum pump 24. Yes. At the time of resin injection, the resin is pushed from each tank toward the resin injection flow path 13 by the pressurizing device 23. A syringe pump is used for the pressurizing device 23 provided via the check valve 12, and it is preferable for a resin that is cured by two-liquid mixing to ensure quantitativeness by simultaneously extruding the syringe. The main agent and the curing agent are mixed by the mixing unit 4 and reach the resin injection channel 13. A resin trap 15 is interposed in the discharge path 14 in order to prevent the resin from flowing into the vacuum pump 7a or the pressure pump 7b.

  The number and positions of the injection ports 8a vary depending on the shape and size of the mold and the number of molded products that are simultaneously molded in the mold, but it is preferable that the number of injection ports 8a be as small as possible. This is to prevent the injection work from becoming complicated due to an increase in the number of locations where the injection flow path 13 from the resin injection device 3 is connected to the injection port 8a.

  The material of the resin injection flow path 13 needs to ensure sufficient flow rate and compatibility with the resin (temperature, solvent resistance, pressure resistance). A tube with a diameter of 5 to 30 mm is used. A pressure resistance of 1.0 MPa or more is required to withstand the injection pressure of the resin, and a heat resistance of 100 ° C. or more is required to withstand the temperature during resin curing, and the thickness is 2 mm. A tube made of fluororesin such as “Teflon (registered trademark)” is suitable. However, other than “Teflon (registered trademark)”, a relatively inexpensive plastic tube such as polyethylene or nylon, or a metal tube such as steel or aluminum may be used.

  Further, the number and positions of the discharge ports 8b vary depending on the shape and size of the molding die, the number of molded products that are simultaneously molded in the mold, and the like, but it is preferable that the number of discharge ports be as small as possible. Moreover, it is preferable that the discharge port 8b is installed at a high position in a direction in which the gas is more likely to float than the injection port 8a so that the gas remaining in the mold can easily escape.

  As for the material of the discharge passage 14, it is necessary to take into consideration the securing of a sufficient flow rate and compatibility with the resin (temperature, solvent resistance, pressure resistance) in the same manner as the resin injection passage 13. The discharge path 14 may be a metal tube such as steel or aluminum, or a plastic tube such as polyethylene, nylon, or “Teflon (registered trademark)”, but “Teflon (registered) having a diameter of 5 to 10 mm and a thickness of 1 to 2 mm. (Trademark) "tube is more preferable from the viewpoint of workability.

  The injection valve 22a and the discharge valve 22b installed in the middle of the resin injection flow path 13 and the discharge path 14 at the time of resin injection can be opened / closed and the diameter of the entire area can be changed by directly sandwiching the flow path by an operator with a vise grip or the like. Can do. For example, as shown in FIG. 5, a vise grip 21 can be provided in the middle of the resin injection passage 13 and the discharge passage 14 connected to the upper die 16 side of the molding die composed of the upper die 16 and the lower die 17. .

  The pressurization of the resin can also provide quantitativeness by a pressurizing method using a syringe pump or the like. The resin injection pressure Pi is preferably in the range of 0.1 to 1.0 MPa. Here, the resin injection pressure Pi refers to the maximum pressure pressurized by the pressurizing device 23 and represents the pressure displayed by the injection pressure gauge 31 of FIG. When the resin is finally completely impregnated into the base material in the mold and reaches the discharge path 14, the discharge path 14 is closed, and after a while, the injection flow path 13 is also closed and the resin injection is finished. The mold 2 is heated by, for example, temperature controllers 25 and 26, thereby curing the resin. The in-mold resin pressure Pm represents the pressure of the in-mold pressure gauge 32.

  In the conventional method, a reinforcing fiber base matched to the shape of the mold is placed in advance and the mold is closed (at this time, part of the reinforcing fiber base is sandwiched between the molds), and then the injection valve 22a. The inside of the mold is vacuumed by the vacuum pump 7a from the discharge passage 14 leading to the discharge valve 22b opened in a closed state, and the resin pressure Pm in the mold is preferably reduced to 0.01 MPa or less, and then the injection valve 22a is turned on. Opening and molding was carried out by pressure injection from the injection flow path 13 until the resin was completely filled in the mold. However, in such a molded article, since a part of the reinforcing fiber base material is sandwiched between the molds, it is necessary to delete such a part. For this reason, in particular, in a thin plate shape (thickness of about 0.5 to 3 mm) such as a cowl of a motorcycle and a precision product is required, a process of finishing to a predetermined shape by an NC-controlled machine tool has been required. . Also, as a method to avoid such machining, make the reinforcing fiber base smaller than the molded shape so that it does not protrude from the predetermined molded shape (a part of the reinforcing fiber base is not sandwiched between the molds). However, as described above, there is an end portion that is not filled with the reinforcing fiber base material. Due to the nature of the end portion, the end portion is susceptible to impacts such as bumping, and the portion where the strength has been reduced is missing. "Is often a problem.

  Therefore, in the present invention, it is slightly smaller than the molding shape by the mold (varies depending on the required performance and the size of the molding shape, but approximately 10 to 20% of the width when the width of the mold shape is within 100 mm, 5 to 15% when the width is 100 mm or more, Before the installation of the main reinforcing fiber base material on which a plurality of textile base materials are piled up on a forming die by a shaping die, the width can be set to be wider by 2 to 10% when the width is 1000 mm or more. Prepare.

  Next, the main fiber reinforced base material prepared in advance is placed in a mold, and in order to make up for a portion smaller than the molded shape, a short fiber and a thermoplastic resin are sprayed to form a sub-reinforced fiber base material. At this time, it is desirable to provide a partition wall in the vicinity of the ridge line of the mold so that the short fiber and the thermoplastic resin do not adhere to an excessive portion. For example, as shown in FIG. 6, an extra filling device 43 is used around the reinforcing fiber base 40 disposed in the lower mold 17 to cut the reinforcing fiber yarns 41 shortly and eject them together with the thermoplastic resin particles 42. A partition wall 44 may be provided so as not to adhere to such a portion, and the sub-reinforcing fiber substrate composed of short fibers can be bonded and integrated with a thermoplastic resin to a portion smaller than the molded shape. The adhesive resin component is not limited to a thermoplastic resin, and may be anything as long as it can be integrally molded and has little influence on physical properties after molding.

  The amount of short fibers varies depending on the purpose, but even if it is equal to or lower by 10 to 20% than the fiber volume content Vf of the main reinforcing fiber substrate, there is no problem because it is not a substrate for obtaining strength. However, when spraying the short fibers is manual, strict caution is required for variations in Vf. As a means for avoiding this danger, it is also preferable to use equipment such as a robot that can reliably perform a predetermined operation.

  This process is performed not only with the mold, but also with the shaping mold, and the auxiliary reinforcing fiber base composed of short fibers is bonded and integrated with the main reinforcing fiber base with the thermoplastic resin, and then installed in the mold. There is no problem.

  In addition, the method according to the present invention is not limited to the end portion of the molded product, for example, a member that becomes sharply thinned, a portion that suddenly increases in thickness, or a woven fabric sheet cannot be shaped smoothly, and the reinforcing fiber The same method is used in places where a uniform fiber volume content Vf cannot be obtained only with a woven fabric sheet, such as a rounded corner R shape that is difficult to be filled with a base material, or reinforcement of a three-dimensional curved surface that requires more cutting than necessary. It is possible to cope with.

  By the method according to the present invention as described above, for example, a cowl of a motorcycle as an FRP structure as shown in FIGS. 7 and 8 can be manufactured. In the illustrated example, a secondary reinforcing fiber base 53 composed of short fibers and a thermoplastic resin is bonded and integrated around a main reinforcing fiber base 52 made of a laminated woven sheet smaller than the molding shape of the cowl 51, and a matrix resin is bonded to them. The FRP cowl 51 in which the FRP part 54 and the FRP part 55 are integrally formed is manufactured by injecting and impregnating the same. Since the FRP structure in which the reinforcing fibers are arranged to every corner of the outer shape, excellent strength and rigidity can be exhibited throughout, and the possibility of chipping and the like can be removed.

  Using the apparatus shown in FIG. 4 and the method shown in FIG. 6, the bike cowl shown in FIGS. 7 and 8 was molded as an FRP structure as follows, and as a result, excellent strength and rigidity were exhibited throughout. And a molded product with no fear of chipping could be obtained.

The lower mold is preliminarily formed into a mold shape with a shaping mold by superposing reinforcing fiber bases made of four fabrics (CO6343B: T300-3K, organization: plain weave, basis weight: 200 g / m ² , manufactured by Toray Industries, Inc.). Imitate. In order to follow the shape of the mold, a thermoplastic pressure-sensitive adhesive material is applied to the reinforcing fiber base and heated in a state following the shape of the mold to integrate a plurality of reinforcing fiber bases. This makes it possible to maintain the shaped shape. The upper mold and the lower mold are both heated to 100 ° C. by the temperature controller 8.

  A pre-shaped main reinforcing fiber substrate is placed in the lower mold. At the same time, as shown in FIG. Next, the reinforcing fiber (carbon fiber roving) is cut to about 5 to 50 mm and sprayed on a portion having a molded shape and no reinforcing fiber substrate. A thermoplastic resin powder is sprayed in accordance with the cut reinforcing fibers. The cut reinforcing fibers were sprayed at such a ratio that the Vf after molding was approximately 40% because the fiber volume content Vf of the main reinforcing fiber base was 50%. The thermoplastic resin was sprayed at a weight ratio of 1% with respect to the Vf fiber content. In the embodiment, since each is performed manually, there is a large partial variation, but it is possible to mechanize the robot arm so as to execute a certain operation. In addition, it is desirable that the cut reinforcing fibers have an overlap so that the main reinforcing fiber base made of a woven fabric is closely adhered and integrated with a thermoplastic resin. When a gap is generated between the main reinforcing fiber base and the cut fiber, problems such as stress concentration occur due to local strength reduction.

  After the main reinforcing fiber base and the auxiliary reinforcing fiber base are thus prepared, the partition is taken out and the upper die is lowered to adhere to the lower die. At this time, the short fiber fits in the molding shape space of the upper mold and the lower mold. Instead of using a mold, use a shaping mold with roughly the same shape as the mold, and heat and bond the main reinforcing fiber base and the sub-reinforcing fiber base in advance to integrate them. May be installed.

  Then, a resin injection flow path 13 is connected to the injection port 8a in FIG. 4, and a discharge path 14 is connected to the discharge port 8b. A tube made of “Teflon (registered trademark)” having a diameter of 12 mm and a thickness of 2 mm was used for both the injection channel 13 and the discharge channel 14. In order to prevent the resin from flowing into the discharge path 14 to the vacuum pump 7a, a resin trap 15 is provided on the way. In order to keep the inside of the mold sealed, the sealing material 20 was arranged on the outer periphery of the mold. Ideally, by closing the upper mold 16, the interior of the mold does not communicate with any place other than the resin injection flow path 13 and the discharge path 14. However, substantially complete sealing is difficult. For example, the pressure of a vacuum pressure gauge (not shown) is monitored with the injection valve 22a disposed in the resin injection path 13 closed and the discharge valve 22b opened. Here, it was decided to check the sealing state as long as 0.01 MPa was maintained for 10 seconds after the vacuum pump 7a was stopped, and there was no problem in molding.

  After discharging from the discharge port 8b with the vacuum pump 7a and confirming with the vacuum pressure gauge that the pressure inside the mold is 0.01 MPa or less, the pressurizing device 23 starts injecting resin. The pressurizing device 23 uses a syringe pump, and is configured to prevent the backflow of the resin to the tank side when the resin is injected. The resin used was “Epicoat” 828 (epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) as the main agent, and the liquid epoxy resin obtained by mixing TR-C35H (imidazole derivative) blended with Toray Industries, Inc. was used. In the resin injection device 3, the main agent 5 and the curing agent 6 were heated in advance to 40 ° C. while being stirred, lowered to a predetermined viscosity, and defoamed with the vacuum pump 24.

  At the initial stage of resin injection, the air in the resin mixing unit 4 and the air in the hose entered and were discarded from a branch path (not shown) without flowing into the mold. The pressure device 23 was set to 200 g / stroke. After discarding the first resin, the injection pressure gauge 31 installed in the injection flow path 13 is used to confirm the injection resin pressure (currently 0.6 MPa), the injection valve 22a is opened, and the resin is injected into the mold. At the start of injection, the discharge passage 14 was opened. At this time, the resin is easily injected into the mold by the pressure in the mold Pm <the supply pressure Pi. When the resin fills the mold, the discharge passage 14 is closed and the resin injection is continued for 1 minute, and the gas in the resin remaining by the above means is crushed by making the injection resin pressure Pi and the mold resin pressure Pm the same just in case. . After 1 minute, the injection path 13 is closed and the resin injection is finished. In this state, it was allowed to stand for 40 minutes and cured.

  The present invention is a method suitable for manufacturing an FRP structure in which reinforcement fibers are desired to be disposed at every corner, in particular, an FRP sheet that is required to maintain the strength of the end portion. The present invention is not limited to the RTM molding method using an epoxy resin, but can be applied to all FRP molding methods based on resin flow.

It is a perspective view of the conventional molded product. It is AA sectional drawing of the molded article of FIG. It is sectional drawing of another conventional molded article. It is an equipment distribution diagram of an RTM molding system concerning one embodiment of the present invention. FIG. 5 is a partial perspective view of a structure that can be employed in the system of FIG. 4. It is a schematic block diagram which shows an example of the method of this invention. It is a perspective view which shows an example of the molded article by this invention method. It is AA sectional drawing of the molded article of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold raising / lowering device 2 Mold 3 Resin injection device 4 Mixing unit 5 Main agent tank 6 Hardener tank 7a Vacuum pump 7b Pressure pump 8a Inlet 8b Outlet 9 Hydraulic unit 10 Hydraulic pump 11 Hydraulic cylinder 12 Check valve 13 Resin Injection passage 14 Discharge passage 15 Resin trap 16 Upper die 17 Lower die 20 Sealing material 21 Vise grip 22a Injection valve 22b Discharge valve 22c Control device 23 Pressurization device 24 Vacuum pump 25, 26 Mold temperature controller 31 Injection pressure gauge 32 In-mold pressure gauge 40 Reinforcing fiber base material 41 Reinforcing fiber yarn 42 Thermoplastic resin particles 43 Filling device 44 Partition 51 Bicycle cowl as FRP structure 52 Main reinforcing fiber base material 53 Sub-reinforcing fiber base material 54, 55 FRP part

Claims (1)

  In the manufacturing method of an FRP structure in which a reinforcing fiber base material is disposed in a mold and cured after being injected with a resin, the main reinforcing material is smaller than the forming shape constituted by a woven sheet as the reinforcing fiber base material. A method for producing an FRP structure, comprising using a reinforcing fiber base material obtained by bonding and integrating a fiber base material and a sub-reinforcing fiber base material composed of short fibers arranged around the fiber base material.

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