JP2007268941A - Composite material molding and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite material molding which suppresses a decrease in axial force and is manufactured with good productivity when it is joined to another part by bolt fastening in a composite material part using a resin as a matrix. <P>SOLUTION: The composite material molding 11 comprises a reinforcing fiber 12 and a matrix resin, and a hole 13 is formed in its part. In the surrounding part 11a of the hole 13, the fiber volume ratio Vf is made higher than that of the other part 11b. In the surrounding part 11a of the hole 13, the amount of the resin per unit volume is decreased and the fiber volume ratio Vf is made higher than that of the other part 11b. The part of the composite material molding 11 in which the hole 13 is formed has a recessed part 14 on its one face. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a composite material molded body and a manufacturing method thereof, and more particularly to a composite material molded body suitable for use in a fastening state with other parts and a manufacturing method thereof.

  Fiber-reinforced composite materials (hereinafter simply referred to as composite materials) are widely used as lightweight structural materials. Structural materials are rarely used alone and are used by being joined to other parts. Compared to bonding with adhesives or bonding with rivets, fastening with bolts (screws), which can be easily disassembled and assembled, and can be easily bonded to metal materials, is easier to maintain than other parts. It is preferable from the viewpoint. However, in the case of a composite material in which the base material (matrix) is a resin, the axial force is reduced due to the creep / stress relaxation phenomenon of the resin, which causes mounting looseness and the like.

As a countermeasure against this, there is a method in which a metal part is insert-molded or press-fitted into the composite material, and a hole is formed in the metal part and the metal part is fastened with a bolt. Further, a fiber reinforced plastic member having a female screw joint portion, wherein continuous reinforcing fibers pass through the thread of the female screw and skew between the pitches, and the screw of the female screw in the member. A fiber-reinforced plastic member characterized by exceeding the top of the valley has been proposed (see Patent Document 1).
Japanese Patent Laid-Open No. 11-325024

  However, in a method in which a metal part is insert-molded or press-fitted into a composite material, fastening with a bolt is satisfactory, but residual stress is generated due to a difference in coefficient of thermal expansion between the metal and the resin, causing other problems. In addition, the manufacturing cost increases. On the other hand, in the case of Patent Document 1, the manufacturing cost is high, and the shapes of usable members are limited.

  The present invention has been made in view of the above-described conventional problems, and its purpose is to suppress a reduction in axial force when a resin-based composite material part is joined to another part by bolt fastening. It is another object of the present invention to provide a composite material molded body that can be manufactured with good productivity and a method for manufacturing the same.

  In order to achieve the above object, the invention according to claim 1 is a composite material molded body composed of reinforcing fibers and a matrix resin, in which holes are formed in part and the fiber volume in the peripheral part of the holes. The rate is higher than other parts. In this invention, since the composite material molded body is formed such that the fiber volume ratio of the peripheral portion of the hole is higher than that of the other portion, creep deformation of the portion is suppressed. And when it joins with other components through the volt | bolt inserted in a hole, the axial force fall of a volt | bolt is suppressed. In addition, since no separate parts (metal parts) are required as a countermeasure against creep, it is possible to easily cope with partial changes in the manufacturing process and to reduce manufacturing costs.

  According to a second aspect of the present invention, in the first aspect of the present invention, the peripheral portion of the hole is formed such that the amount of resin per unit volume is reduced and the fiber volume ratio is higher than that of the other portions. In this invention, since it is not necessary to increase the amount of reinforcing fibers and the amount of resin is reduced, the material cost is reduced as compared with the case where the reinforcing fiber is increased to increase the fiber volume ratio.

  According to a third aspect of the present invention, in the second aspect of the present invention, the portion where the hole is formed has a concave portion on one side. In this invention, by providing a convex portion on one mold of the molding die, a part of the reinforcing fiber is compressed from the other part at the time of molding, and a composite material molded body having a high fiber volume fraction is easily manufactured. be able to.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the peripheral portion of the hole is formed such that the amount of fibers per unit volume is increased and the fiber volume ratio is higher than other portions. In this invention, even if it is the same thickness, a portion with a high fiber volume ratio and a portion with a low fiber volume ratio are formed, so that the composite material molded body can be easily taken out from the mold during manufacturing.

  According to a fifth aspect of the present invention, there is provided a reinforcing fiber body arranging step of arranging a reinforcing fiber body in a cavity of a mold, and a predetermined of the reinforcing fiber body disposed in the cavity in a state where the mold is closed. Reinforcing fiber body pressing step for pressing the reinforcing fiber body so that the fiber volume ratio at the location is higher than the fiber volume ratio of other portions, and a resin curing step for curing the resin impregnated in the pressed reinforcing fiber body And a hole processing step of forming a hole in the portion where the fiber volume fraction of the molded body after resin curing is increased. Here, “reinforcing fiber body” means only a preform in which a fiber is processed into a two-dimensional fiber structure such as a woven fabric, a knitted fabric or a non-woven fabric, or a three-dimensional structure such as a three-dimensional woven fabric, a three-dimensional knitted fabric or a braided string. It does not mean, but also means a prepreg in which a raw fiber (fiber bundle) is arranged or a semi-cured state (B stage state) in which a fiber is impregnated with a resin.

  In this invention, by closing the mold in a state where the reinforcing fiber body is disposed in the cavity of the mold, the fiber volume ratio of the predetermined portion of the reinforcing fiber body disposed in the cavity is changed to the fiber volume ratio of the other portion. Get higher. Therefore, by making a predetermined part a part that forms a hole through which a bolt is inserted, in a composite material (FRP) part using a resin as a matrix, when it is joined to another part by bolt fastening, the axial force is reduced. A composite molded body that can be suppressed can be manufactured with high productivity.

  ADVANTAGE OF THE INVENTION According to this invention, in the composite material component which used resin as the matrix, when joining with other components by bolt fastening, the fall of axial force can be suppressed and it can manufacture with sufficient productivity.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3 schematically show the composition of the composite material molded body and the molding die. For convenience of illustration, the respective parts are exaggerated for easy understanding. The ratio of dimensions such as length and thickness is different from the actual ratio. This is the same in other embodiments.

  As shown in FIG. 1, the composite material molded body 11 is composed of reinforcing fibers 12 and a matrix resin (not shown), and a hole 13 is partially formed. The peripheral portion 11a of the hole 13 is formed such that the fiber volume fraction Vf is higher than that of the other portion 11b. The peripheral portion 11a of the hole 13 is formed such that the amount of resin per unit volume is reduced and the fiber volume ratio Vf is higher than that of the other portion 11b. As for the part in which the hole 13 of the composite-material molded object 11 is formed, the single side | surface (upper surface in FIG. 1) becomes the recessed part 14. FIG.

  As the reinforcing fiber, for example, glass fiber, carbon fiber (carbon fiber), aramid fiber and the like are used, and carbon fiber is preferable. As the resin, a thermosetting resin such as an unsaturated polyester resin, an epoxy resin, or a phenol resin is used.

Next, a method for manufacturing the composite material molded body 11 configured as described above will be described.
When the composite material 11 is manufactured, a mold is used. As shown in FIG. 2A, the molding die 20 includes a lower die 21 having a cavity 21a, and an upper die 22 that covers the entire cavity 21a and includes a protruding portion 22a that partially protrudes into the cavity 21a. It has. Although not shown, the molding die 20 is a decompression passage for reducing the pressure in the cavity 21a in a mold-clamped state, like a resin-impregnating die (molding die) used in the resin transfer molding (RTM) method. And a resin injection passage for injecting resin into the cavity 21a.

  First, as shown in FIG. 2A, a reinforcing fiber body arranging step of arranging the reinforcing fibers 12 in the cavity 21a of the lower die 21 is performed in a state where the upper die 22 is arranged at the open position. In this embodiment, a fiber bundle is used as the reinforcing fiber 12, the fiber bundle is arranged in a plurality of layers, and the arrangement direction of the fiber bundles constituting the adjacent layers is orthogonal to be filled in the cavity 21 a. Thus, the reinforcing fiber body 15 is configured.

  Next, a reinforcing fiber body pressing step is performed. In the reinforcing fiber body pressing step, as shown in FIG. 2 (b), the upper die 22 is disposed at the closed position and the forming die 20 is closed. When the upper mold 22 is disposed in a closed state (closed position), the reinforcing fiber 12 corresponding to the convex portion 22a is pressed, and the fiber volume fraction Vf of the reinforcing fiber body 15 corresponding to the convex portion 22a. Becomes higher than the fiber volume fraction Vf of other portions.

Next, in a state where the inside of the cavity 21a is decompressed to a state close to vacuum, a thermosetting resin is injected into the cavity 21a, and the reinforcing fiber body 15 is impregnated with the thermosetting resin.
Next, a resin curing step is performed in which the mold 20 is heated to a temperature equal to or higher than the thermosetting temperature of the resin by a heating unit (not shown), and the thermosetting resin impregnated in the reinforcing fiber body 15 is cured. Thereafter, after the temperature of the molding die 20 is lowered, the molding die 20 is opened, the molded body after resin curing is taken out from the lower mold 21, and the holes 13 are formed in the portions where the fiber volume ratio Vf of the molded body is increased. A hole forming step to be formed is performed. The hole processing is performed by, for example, mechanical processing using a drill, punching processing, water jet processing, or the like. Thereafter, external processing such as deburring and cutting of unnecessary parts is performed, and the production of the composite material molded body 11 is completed as shown in FIG.

  As shown in FIG. 3, the composite material molded body 11 configured as described above is joined (fixed) in a state in which it is fastened and fixed to other parts 16 by bolts 17 and nuts 18 penetrating through the holes 13. Have been used. In the composite material molded body 11, the fiber volume ratio Vf of the reinforcing fiber 12 of the base material is locally increased only at the fastening portion by the bolt 17. Therefore, the absolute amount of the resin that causes the creep deformation of the fastening portion is reduced, and a reduction in axial force is suppressed.

  When the amount of reinforcing fibers in the composite material is the same, the fiber volume ratio Vf increases as the thickness of the composite material decreases as shown in FIG. For example, when the thickness is reduced from 5 mm to 4 mm, Vf increases from 50% to 62.5%. Further, as shown in FIG. 4B, the ratio Et / Em between the elastic modulus (non-axial elastic modulus) Et in the out-of-plane direction of the composite and the elastic modulus Em of the resin is the fiber volume ratio. It increases with increasing Vf. As for the increase rate, when the value of the fiber volume fraction Vf increases by 10%, for example, from 50% to 60%, the value of Et / Em increases by approximately 25%. Therefore, when the fiber thickness ratio Vf is increased by reducing the plate thickness of the composite material molded body 11, sag (surface depression) is suppressed due to the improvement of the elastic modulus Et in the out-of-plane direction and the reduction of the surface resin layer, which is high. A joint (fastening portion) that can withstand axial force is obtained.

According to this embodiment, the following effects can be obtained.
(1) The composite material molded body 11 is composed of reinforcing fibers 12 and a matrix resin, and a hole 13 is formed in a part thereof, and a fiber volume ratio Vf of a peripheral part 11a of the hole 13 is formed higher than other parts. Yes. Accordingly, since creep deformation of the peripheral portion 11a of the hole 13 is suppressed, a reduction in the axial force of the bolt 17 is suppressed when joined to another component 16 via the bolt 17 inserted through the hole 13. In addition, since no separate parts (metal parts) are required as a countermeasure against creep, it is possible to easily cope with a partial change in the manufacturing process and to reduce costs.

  (2) The peripheral portion 11a of the hole 13 is formed such that the amount of resin per unit volume is reduced and the fiber volume ratio Vf is higher than that of the other portion 11b. Therefore, it is not necessary to increase the amount of the reinforcing fibers 12, and the amount of resin is reduced. Therefore, the material cost is reduced as compared with the case where the reinforcing fiber 12 is increased to increase the fiber volume ratio Vf.

  (3) The part where the hole 13 is formed has a concave part 14 on one side. Therefore, by providing the convex portion 22a on one mold of the mold 20 (the upper mold 22 in this embodiment), a part of the reinforcing fiber 12 is compressed from the other part at the time of molding and a part of the fiber volume ratio Vf is obtained. The composite material molded body 11 having a high height can be easily produced.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, as a method for increasing the fiber volume fraction Vf of a part of the composite material molded body 11, the molding die 20 uses a separate part without changing the conventional technique. It is different from the form. Detailed description of the parts basically similar to those of the first embodiment will be omitted.

  As shown in FIGS. 5A to 5C, the molding die 20 includes a lower die 21 and an upper die 22, and the upper die 22 does not have a convex portion 22 a and has a constant plate thickness unlike the first embodiment. The configuration is the same as that of the prior art. In the mold closed state, a washer 19 is used as a separate part from the mold 20 in order to increase the fiber volume ratio Vf of a part of the reinforcing fiber body 15 to be higher than the fiber volume ratio Vf of the other part. The washer 19 is formed in a truncated cone shape.

  When forming the composite body 11, first, as shown in FIG. 5A, the washer 19 is placed at a predetermined position in the cavity 21 a of the lower mold 21 with the upper mold 22 placed in the open position. It arrange | positions in the state which a bottom part contact | connects the inner surface of the cavity 21a. In this state, a reinforcing fiber body arranging step for arranging the reinforcing fibers 12 is performed. And as shown to Fig.5 (a), the reinforced fiber body 15 is comprised because the reinforced fiber 12 is satisfy | filled in the cavity 21a.

  Next, as shown in FIG. 5 (b), a reinforcing fiber body pressing step is performed in which the upper die 22 is placed in the closed position and the molding die 20 is closed. When the upper mold 22 is placed in the closed state (closed position), the reinforcing fiber 12 corresponding to the washer 19 is pressed more strongly than the reinforcing fiber 12 not corresponding to the washer 19 to correspond to the washer 19. The fiber volume fraction Vf of the reinforcing fiber body 15 in the portion becomes higher than the fiber volume fraction Vf in the other portion.

  Next, in the same manner as in the first embodiment, after the thermosetting resin is impregnated into the reinforcing fiber body 15, a resin curing step is performed. Then, after the temperature of the mold 20 is lowered, the molded body after resin curing is taken out from the lower mold 21, and the hole 13 is formed in the portion facing the hole of the washer 19 in the portion where the fiber volume ratio Vf of the molded body is increased. A hole forming step of forming is performed. Thereafter, external processing such as deburring and cutting of unnecessary portions is performed, and the production of the composite material molded body 11 is completed as shown in FIG. That is, the washer 19 is integrally formed in the composite material molded body 11 of this embodiment. This composite material molded body 11 is also used by being joined (fixed) to another component 16 in a state where it is fastened and fixed with bolts 17 and nuts 18 penetrating through the holes 13.

Therefore, according to this embodiment, the following effects can be obtained in addition to the same effects as (1) and (2) in the first embodiment.
(4) As a method for increasing the fiber volume fraction Vf of a part of the composite material molded body 11, the molding die 20 uses a washer 19 as a separate part without changing the prior art. Therefore, an existing mold can be used as the mold 20 and the manufacturing cost is reduced.

  (5) In the case of changing the area or the number of portions for increasing the fiber volume ratio Vf, in the configuration of the first embodiment, it is necessary to prepare the upper mold 22 correspondingly. In this embodiment, a washer is used. It is possible to cope easily by changing the size or number of 19.

  (6) Since the washer 19 is integrated with the composite material molded body 11, when the composite material molded body 11 is fastened to the other parts 16 with the bolts 17 and the nuts 18, it is necessary to prepare one washer. Absent.

  (7) Due to the structure of the mold 20, when the upper mold 22 is opened, the upper mold 22 protrudes into the cavity 21a even if the upper mold 22 cannot be moved away from the lower mold 21. Therefore, the upper mold 22 can be opened by sliding in parallel with the lower mold 21.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. This third embodiment is the same as the second embodiment in that the molding die 20 is the same as the second embodiment in that it does not change the conventional technique as a method for increasing the fiber volume fraction Vf of a part of the composite material molded body 11. The point which does not use is greatly different from the second embodiment. Detailed description of the parts basically similar to those of the second embodiment will be omitted.

  As shown in FIGS. 6A and 6B, the molding die 20 includes a lower die 21 and an upper die 22, and the upper die 22 has no convex portion 22a and is formed with a constant plate thickness unlike the first embodiment. The configuration is the same as that of the prior art.

  When forming the composite material molded body 11, first, a reinforcing fiber body arranging step is performed in which the reinforcing fibers 12 and 12 a are arranged in the cavity 21 a of the lower mold 21 in a state where the upper mold 22 is arranged in the open position. . At that time, as shown in FIG. 6 (a), the amount of the reinforcing fibers 12 and 12a to be arranged in the portion where the fiber volume fraction Vf should be increased is increased from the amount of the reinforcing fibers 12 arranged in the other portions. Deploy. In this embodiment, in the portion where the amount of the reinforcing fibers 12 and 12a is increased, the reinforcing fibers 12a are laminated in a state (orthogonal state) in which the reinforcing fibers 12 and the arrangement direction are different.

  Then, when the predetermined amount of reinforcing fibers 12 and 12a are arranged and the reinforcing fiber body arranging step is finished, the upper die 22 is arranged at the closed position and the forming die 20 is closed as shown in FIG. 6B. A reinforced fiber body pressing step is performed. When the upper die 22 is disposed in a closed state (closed position), the portion of the reinforcing fiber body 15 in which the reinforcing fiber 12a is added to the reinforcing fiber 12 and the amount of fibers is increased is caused by the lower die 21 and the upper die 22. It is pressed more strongly than other parts. As a result, the fiber volume ratio Vf of the part is higher than the fiber volume ratio Vf of the other part.

  Next, the resin curing step is performed after the reinforcing fiber body 15 is impregnated with the thermosetting resin in the same manner as in both the above embodiments. And after the temperature of the shaping | molding die 20 falls, the molded object after resin hardening is taken out from the lower mold | type 21, and the hole processing process which forms the hole 13 in the part in which the fiber volume fraction Vf became high is performed. . Thereafter, external processing such as deburring and cutting of unnecessary portions is performed, and the production of the composite material molded body 11 is completed as shown in FIG. This composite material molded body 11 is also used by being joined (fixed) to another component 16 in a state where it is fastened and fixed with bolts 17 and nuts 18 penetrating through the holes 13.

Therefore, according to this embodiment, the following effects can be obtained in addition to the same effects as (1), (2) in the first embodiment and (7) in the second embodiment.
(8) As a method of increasing the fiber volume fraction Vf of a part of the composite material molded body 11, the molding die 20 has a fiber volume when the reinforcing fibers 12 and 12a are disposed in the cavity 21a without changing the conventional technique. More reinforcing fibers 12 and 12a are arranged in a portion corresponding to a portion where the rate Vf should be increased than in other portions. Accordingly, even if the thickness of the composite material molded body 11 is constant, the amount of fibers per unit volume of the portion where the holes 13 are formed is increased and the fiber volume ratio Vf is formed higher than that of the other portions. As a result, the composite material molded body 11 can be easily removed from the mold 20 during manufacture.

  (9) When changing the area or number of the part which raises fiber volume ratio Vf, it can respond easily by adding the reinforced fiber 12a arrange | positioned to the said part. For example, when it is necessary to form the plurality of holes 13 so as to be aligned in the direction perpendicular to the paper surface of FIGS. 6A and 6B, it is possible to easily cope with this by making the reinforcing fibers 12a longer.

The embodiment is not limited to the above, and may be embodied as follows, for example.
In the second embodiment, instead of arranging the washer 19 in contact with the cavity 21a of the lower mold 21, the washer 19 may be arranged on the reinforcing fiber body 15 arranged in the cavity 21a. Also in this case, the same composite material molded body 11 as in the second embodiment can be manufactured.

  In the second embodiment, the washer 19 is disposed on the position where the hole 13 is in contact with the cavity 21a corresponding to the predetermined position where the hole 13 is to be formed and on the reinforcing fiber body 15 disposed in the cavity 21a. Also good. In this case, it is possible to manufacture the composite material molded body 11 in which washers 19 are respectively integrated at locations corresponding to both ends of the hole 13.

  In the second embodiment, instead of using the washer 19 as a separate part, the separate part is used only for the purpose of increasing the fiber volume fraction Vf of a predetermined portion of the reinforcing fiber body 15, and a composite material molded body After 11 is formed, another part may be removed from the composite material molded body 11. In this case, the degree of freedom of the shape of another part is increased.

  ○ Instead of providing the convex portion 22a on the upper mold 22 of the molding die 20, a convex portion for pressing the reinforcing fiber body 15 to the lower mold 21 to partially increase the fiber volume fraction Vf may be provided. Also in this case, the composite material molded body 11 can be manufactured in the same manner as in the first embodiment.

The composite material molded body 11 is not limited to a flat plate, and may be a member having a portion having a different thickness, a curved portion, or a bent portion.
O Instead of arranging the reinforcing fiber 12 in the cavity 21a to form the reinforcing fiber body 15, a preform obtained by processing the reinforcing fiber outside the cavity 21a may be used as the reinforcing fiber body 15. Examples of the preform include two-dimensional fiber structures such as woven fabrics, knitted fabrics, and nonwoven fabrics, and three-dimensional structures such as three-dimensional woven fabrics, three-dimensional knitted fabrics, and braids.

  The resin constituting the composite material molded body 11 is not limited to a thermosetting resin, and may be a thermoplastic resin. When using a thermoplastic resin, the resin is impregnated with the mold 20 heated to a temperature equal to or higher than the melting temperature of the resin.

  As the reinforcing fiber body 15, a prepreg in which fibers are impregnated with a resin in advance and processed into a semi-cured state (B stage state) may be disposed in the cavity 21a, or the prepreg and the reinforcing fiber 12 may be mixed and disposed. .

The following technical idea (invention) can be understood from the embodiment.
(1) In the invention according to claim 5, a part separate from the molding die is disposed at a location corresponding to a predetermined portion of the reinforcing fiber body in the cavity of the molding die, and the separate body is placed in the mold closed state. A predetermined part of the reinforcing fiber body is pressed with a part so that the fiber volume ratio Vf of the part is higher than the fiber volume ratio Vf of other parts.

  (2) In the invention according to claim 5 or technical idea (1), a preform is used as the reinforcing fiber body.

The schematic cross section of the composite-material molded object in 1st Embodiment. (A)-(c) is a schematic cross section explaining the manufacturing method of a composite material molded object. The schematic cross section which shows the use condition of a composite material molded object. (A) is a graph showing the relationship between the thickness of the composite material and the fiber volume fraction, and (b) is a graph showing the relationship between the ratio of the out-of-plane elastic modulus Et and the resin elastic modulus Em of the composite material and the fiber volume fraction. . (A)-(c) is a schematic cross section explaining the manufacturing method of the composite material molded object in 2nd Embodiment. (A)-(c) is a schematic cross section explaining the manufacturing method of the composite material molded object in 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Composite material molded object, 11a ... Surrounding part, 11b ... part, 12, 12a ... Reinforcement fiber, 13 ... Hole, 14 ... Recessed part, 15 ... Reinforcement fiber body, 20 ... Mold, 21a ... Cavity.

Claims (5)

A composite material formed of a reinforced fiber and a matrix resin,
A composite material molded body, wherein a hole is formed in a part, and a fiber volume ratio of a peripheral part of the hole is formed higher than that of another part.   2. The composite molded body according to claim 1, wherein the peripheral portion of the hole is formed such that the amount of resin per unit volume is reduced and the fiber volume ratio is higher than that of the other portion.   The composite material molded body according to claim 2, wherein a portion where the hole is formed has a concave portion on one side.   2. The composite material molded body according to claim 1, wherein the peripheral portion of the hole is formed such that an amount of fibers per unit volume is increased and a fiber volume ratio is higher than other portions. A reinforcing fiber body arranging step of arranging the reinforcing fiber body in the cavity of the mold,
Reinforcing fiber body that presses the reinforcing fiber body so that the fiber volume ratio at a predetermined position of the reinforcing fiber body disposed in the cavity is higher than the fiber volume ratio of other portions in a state where the mold is closed. Pressing process;
A resin curing step of curing the resin impregnated in the pressed reinforcing fiber body;
And a hole processing step of forming a hole in the portion of the molded body after resin curing where the fiber volume ratio is high.

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