JP4544266B2 - Fiber reinforced composite - Google Patents

Description

  The present invention relates to a fiber reinforced composite material.

  Fiber reinforced composite materials, especially fiber reinforced plastics, are lightweight and high in strength, and are widely used as structural materials for spoilers in automobiles. Examples of the fiber used for the fiber reinforced composite material include carbon fiber, glass fiber, and polyaramid fiber.

  The most commonly used fiber reinforced composites with short fibers and long fibers that are not continuous fibers are used as reinforcing materials because the fibers are cut and their orientation is difficult to control. There is. In addition, fiber reinforced composites made of two-dimensional fiber structures using pre-cut fibers, such as non-woven fabrics using chopped fibers and fabrics using check yarns, are fiber reinforced composites made of short fibers and long fibers. Stronger than the material. However, the cutting process increases the cost. Further, when the final product is thick, a plurality of non-woven fabrics and woven fabrics are used, so that the strength in the thickness direction is weak and the bending strength is also weak.

  When the final product is thick and requires high strength, a fiber-reinforced composite material using a three-dimensional fiber structure using continuous fibers as a reinforcing material is used. Since the fibers are continuous and are three-dimensionally configured, the strength is very high.

The fiber reinforced composite material needs to be deformed into a part shape at the time of molding. Conventionally, a two-dimensional fiber structure has a method in which a coarsely woven fabric is partially fused with a thermoplastic resin in order to facilitate deformation. Patent Document 1 discloses a preform formed by deep drawing including a bi-directional woven fabric using warp yarns and weft yarns as reinforcing fibers. In this preform, a thermoplastic polymer is linearly and continuously or discontinuously attached to at least one of the warp and weft, and the minimum crossing angle of the weaving yarn extending in two directions of the reinforcing fabric is 20 to 40. It is a degree. However, when using woven fabric as a reinforcing material, there are restrictions even if the eyes are rough, so there is a limit to deformation, and threads (fibers) with different arrangement directions interfere with each other, so the fibers are arranged straight. It is difficult to increase the strength of the fiber reinforced composite material.
JP-A-8-337666

  A three-dimensional fiber structure using continuous fibers is more difficult to deform in accordance with the part shape than a two-dimensional fiber structure. Therefore, it is necessary to manufacture a three-dimensional fiber structure using continuous fibers in a shape that matches the product shape in advance so that it does not need to be deformed. However, in this case, the manufacturing cost, the jig and the like of the fiber structure are required for each product shape, so the cost is high.

  This invention is made | formed in view of the above problem, The objective is to provide the fiber reinforced composite material which can be manufactured at low cost.

In order to achieve the above object, the invention according to claim 1 is directed to a continuous fiber in which a bundle of continuous fibers is arranged in the thickness direction of the laminated fiber group on the entire surface of the laminated fiber group in which at least biaxial orientation is performed. A plurality of through-holes that penetrate in the thickness direction of the laminated fiber group are formed in a partial region of the fiber structure, and the laminated fibers are formed by the through-holes. the fiber structure continuous fibers are cut constituting the continuous fibers and said binding yarn constituting the group, a fiber reinforced composite material impregnated with a matrix, the continuous fibers and said coupling constituting the front Symbol laminated fiber group continuous fibers is deformed in the area being cut that make up the yarn. Here, the “yarn” does not mean only a twisted yarn but also includes a fiber bundle (so-called roving) in which a large number of fibers are bundled and are not substantially twisted.

  In the present invention, by cutting a part of continuous fibers in the area of the part of the laminated fiber group bonded by the binding yarn, the binding force is reduced in the area. Therefore, the restraining force is reduced in the region where the continuous fibers are cut and deformation is easy, and it is not necessary to manufacture a fiber structure having a shape matched to the product shape, and the manufacturing cost of the fiber reinforced composite material can be suppressed. .

The invention according to claim 2 is the invention according to claim 1, wherein the binding yarns are uniformly arranged on the entire surface of the laminated fiber group. Therefore, it is easy to manufacture the fiber reinforced composite material.
The invention according to claim 3 is the invention according to claim 1 or 2, wherein the binding yarn is folded back on one surface of the laminated fiber group to form a U-shaped loop. A retaining thread made of continuous fibers is inserted so as to pass through the thread. Therefore, it is possible to suppress the binding yarn from coming off.

The invention according to claim 4 is the continuous fiber according to any one of claims 1 to 3 in the region of at least one of both ends in the length direction and width direction of the fiber structure. Is not disconnected.
The invention according to claim 5 is formed by inserting and retracting a cutting needle a plurality of times in the thickness direction of the laminated fiber group in the invention according to any one of claims 1 to 4. ing.

  As described in detail above, the invention described in each claim is a fiber-reinforced composite material that can be manufactured at low cost.

(First embodiment)
Hereinafter, an embodiment in which the present invention is embodied in a fiber reinforced composite material using a thermoplastic resin as a matrix resin will be described with reference to FIGS.

  First, the fiber structure will be described. As shown in FIG. 1B, the x yarns 4a as a fiber bundle composed of continuous fibers are arranged in one direction (a direction perpendicular to the paper surface in FIG. 1B) to form an x yarn layer 4. . Similarly, the y yarn 5a as a fiber bundle made of continuous fibers is also arranged in one direction (left and right in FIG. 1B) to form the y yarn layer 5. A plurality of x yarn layers 4 and y yarn layers 5 are alternately laminated to form a biaxially oriented laminated fiber group 6. The two axes are orthogonal to each other. The thickness direction yarns 7 are uniformly inserted and arranged on the entire surface of the laminated fiber group 6 in the thickness direction of the laminated fiber group 6. The thickness direction yarn 7 is folded back into a U-shape on one surface (lower surface in FIG. 1B) of the laminated fiber group 6, and the thickness direction yarn 7 is formed on the other surface (upper surface in FIG. 1B). Are continuously inserted in the laminated fiber group 6 at the insertion position separated by the arrangement pitch of. The retaining thread 8 is inserted through a portion where the thickness direction thread 7 is folded back into a U shape. By tightening the thickness direction thread 7 and the retaining thread 8, the x thread layer 4 and the y thread layer 5 are joined. Among the laminated fiber group 6 joined by the thickness direction thread 7 and the retaining thread 8, a part of the x thread 4a, the y thread 5a, the thickness direction thread 7, and the retaining thread 8 is cut in a part of the region. Thus, the cut region 3 is formed.

  As shown in FIG. 1A, the fiber structure 1 includes a non-cut region in which the x yarn 4a, the y yarn 5a, and the like of the laminated fiber group 6 joined by the thickness direction yarn 7 and the retaining yarn 8 are not cut. 2 and a cutting region 3 where x yarn 4a, y yarn 5a and the like are cut. The cutting region 3 is provided in a portion that needs to be deformed when forming into a product shape. Further, both end portions of the fiber structure 1 are non-cut regions 2. Since a part of each thread | yarn is cut | disconnected in the cutting | disconnection area | region 3, compared with the non-cut | disconnecting area | region 2, restraint force is weak and it is easy to deform | transform.

  Continuous fibers are used as the x yarn 4a, the y yarn 5a, the thickness direction yarn 7 and the retaining yarn 8. In this embodiment, carbon fibers are used as continuous fibers. Carbon fiber has about 3000 to 24000 filaments. The arrangement pitch of the thickness direction yarns 7 is about 3 to 5 mm. The thickness of the fiber structure 1 is about 5 mm.

Next, a method for producing a fiber reinforced composite material using a thermoplastic resin as a matrix resin will be described.
As shown in FIGS. 2A and 2B, the rectangular frame body 9 is provided with a large number of pins 9b so as to surround the hole 9a. The pitch of the pins 9b is adjusted to the pitch of the x yarn 4a and the y yarn 5a.

  As shown in FIG. 2 (a), the x yarn 4a is folded in a state of engaging with the pin 9b to form the x yarn layer 4 oriented in one direction. Next, as shown in FIG. 2 (b), the y yarn 5a is similarly folded in a state of engaging with the pin 9b and oriented in one direction perpendicular to the x yarn 4a to form the y yarn layer 5. . By repeating this a predetermined number of times, the laminated fiber group 6 is formed. 2 (a) and 2 (b), the arrangement interval of the x yarn 4a and the y yarn 5a is widely illustrated, but in actuality, the adjacent x yarns 4a or the y yarns 5a are in contact with each other. Arranged.

  Next, the thickness direction yarn 7 is inserted into the laminated fiber group 6 by a method disclosed in, for example, Japanese Patent Laid-Open No. 8-218249. More specifically, in the thickness direction of the laminated fiber group 6, an insertion needle (not shown) having a hole at the tip and hooking the thickness direction thread 7 into the hole is inserted. The insertion needle is advanced and inserted until the hole of the insertion needle to which the thickness direction thread 7 is hooked penetrates the laminated fiber group 6. Thereafter, the insertion needle is pulled back slightly. As a result, the thickness direction thread 7 is in a state where a U-shaped loop is formed.

  Next, the stopper thread needle (not shown) stops when it passes through the U-shaped loop and reaches the end of the laminated fiber group 6. At this time, the retaining thread 8 is hooked to the tip of the retaining thread needle. Then, the retaining thread needle is pulled back, and the retaining thread 8 is inserted into the U-shaped loop of the thickness direction thread 7. In this state, the insertion needle is pulled back, and the retaining thread 8 is tightened by the thickness direction thread 7 to join the thread layers. This process is performed uniformly on the entire surface of the laminated fiber group 6, and a fiber structure in which each thread layer of the laminated fiber group 6 is bonded with the thickness direction thread 7 is manufactured.

  Next, a cutting needle attached in place of the insertion needle is inserted / retracted a plurality of times into an area of the fiber structure that needs to be deformed when it is formed into a desired product shape. According to the number of times the cutting needle is inserted / retracted, the x yarn 4a, the y yarn 5a, the thickness direction yarn 7, and the retaining yarn 8 in the region are cut to form the cutting region 3. Thus, the fiber structure 1 composed of the non-cut region 2 and the cut region 3 is manufactured. However, the entire region of the fiber structure 1 does not become the cutting region 3.

  The fiber structure 1 obtained as described above is impregnated with a thermoplastic resin by a general impregnation method such as a melt impregnation molding method, and cooled to form a plate-shaped material for molding. Next, the material is heated and softened before molding, then press-molded with a press-molding machine and cooled to obtain a product-shaped fiber-reinforced composite material 10 as shown in FIG.

This embodiment has the following effects.
(1) Reinforcement of fiber structure 1 in which a part of continuous fibers in a region of a portion of the fiber structure in which the yarn layers of the laminated fiber group 6 are joined by the thickness direction yarns 7 are cut. A fiber reinforced composite material is produced. Therefore, it is not necessary to manufacture a three-dimensional fiber structure having a shape that matches the product shape, and costs can be reduced.

  (2) The continuous fiber is cut when the cutting needle is inserted into and pulled back from the fiber structure in which each thread layer of the laminated fiber group 6 is joined by the thickness direction thread 7. Therefore, the production of the fiber structure 1 is easy.

(3) The cutting region 3 is formed by inserting and retracting the cutting needle. Therefore, the restraining force of the cutting region 3 can be easily adjusted by the number of insertions / retractions.
(4) The cutting region 3 is formed by inserting / retracting a cutting needle attached instead of the insertion needle. Therefore, existing equipment can be used and manufacturing is easy.

  (5) The restraining force is reduced only in the cutting region 3, and the non-cutting region 2 is composed of continuous fibers and the restraining force is maintained. Therefore, the handleability of the fiber structure 1 is good even when the fiber structure 1 is not impregnated with resin.

(6) Non-cutting regions 2 are provided at both ends of the fiber structure 1. Therefore, the handleability of the fiber structure 1 is good even when the fiber structure 1 is not impregnated with resin.
(7) The constraining force is reduced in the cutting region 3, which is a portion that needs to be deformed. Therefore, the fiber structure 1 is deformed according to the shape of the part by press working, and wrinkles are not generated.

  (8) The binding force is reduced only in the cutting region 3 which is a portion that needs to be deformed, and the non-cutting region 2 is composed of continuous fibers. Therefore, the strength as a fiber reinforced composite material using a three-dimensional fiber structure of continuous fibers as a reinforcing material in the product shape is maintained.

(Second Embodiment)
Next, a second embodiment will be described. In this embodiment, the structure / manufacturing method of the fiber structure 1 is the same as that of the above embodiment, and the molding process is greatly different. The same parts as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

The fiber structure 1 obtained by the above embodiment is put into a mold and closed. At this time, since the region of the portion that needs to be deformed is the cut region 3, the fiber structure 1 is deformed according to the mold and becomes a product shape. Next, after a thermosetting resin is injected and impregnated, it is cured by heating to obtain a product-shaped fiber-reinforced composite material 10 as shown in FIG. (RTM method: Resin transfer molding method)
In addition to the same effects as (1) to (8) of the above embodiment, this embodiment has the following effects.

(9) It can be molded using a thermosetting resin. Therefore, it is possible to produce a fiber-reinforced composite material having a higher strength than when a thermoplastic resin is used.
The embodiment is not limited to the above, and may be configured as follows, for example.

○ Reinforcing fiber may not be carbon fiber. For example, glass fiber, polyaramid fiber, ceramic fiber, etc. may be used.
Not all the same fibers are used as the x yarn 4a, the y yarn 5a, the thickness direction yarn 7 and the retaining yarn 8, but different fibers may be used depending on the yarn. For example, the fibers of the x yarn 4a may be lower in strength than the fibers of the y yarn 5a in accordance with the physical properties required for the fiber reinforced composite material 10. In this case, the manufacturing cost can be reduced without making the fiber reinforced composite material 10 excessive quality.

  The thickness direction yarns 7 do not have to be uniformly arranged on the entire surface of the laminated fiber group 6. For example, a region where the thickness direction yarns 7 are dense has a strong binding force, and a region where the thickness direction yarns 7 are sparse has a low binding force. Therefore, the restraining force can be adjusted.

  The laminated fiber group 6 only needs to be at least biaxially oriented, and two types of yarn layers, that is, an x yarn layer 4 made of x yarns 4a and a y yarn layer 5 made of y yarns 5a arranged so as to be orthogonal to each other. Need not be formed. For example, the laminated fiber group 6 may be formed of yarn layers arranged so that the arranged yarns are not orthogonal to each other.

O The laminated fiber group 6 may have a triaxial or more orientation. For example, a bias yarn layer may be included depending on the strength required for the product.
○ The fiber structure may not be a flat plate. A curved surface having a small curvature may be used.

O Instead of using the retaining thread 8, the thread layers may be joined by general stitching using only the thickness direction thread 7.
The thickness direction yarns 7 may not be arranged in a continuous state from one end to the other end of the fiber structure 1. Even if it is discontinuous, it is only necessary to penetrate through each thread layer.

  O When manufacturing the fiber reinforced composite material 10, it is not restricted to forming the one fiber reinforced composite material 10 (product) with the one fiber structure 1. FIG. Depending on the product shape or required performance, a plurality of fiber structures 1 may be arranged or stacked.

  In order to form the cutting region 3, the cutting needle need not be attached instead of the insertion needle. For example, needle punching may be performed in a separate process. In addition, a small blade that does not break the fiber structure even if it is not a needle may be used.

(Circle) 1st Embodiment is not restricted to press molding. For example, vacuum forming may be used. Any method may be used as long as the sheet-like fiber structure 1 is impregnated with a thermoplastic resin and then molded.
The second embodiment is not limited to the RTM method. Any method may be used as long as the sheet-like fiber structure 1 is impregnated with a thermosetting resin.

  (Circle) the matrix resin which comprises the fiber reinforced composite material 10 of 2nd Embodiment is not restricted to a thermosetting resin, A thermoplastic resin may be sufficient. In this case, heating after impregnating the resin becomes unnecessary, and natural cooling may be performed.

  The fiber reinforced composite material 10 may have a matrix other than resin, for example, metal. In this case, as the fiber constituting the fiber structure 1, carbon fiber, ceramic fiber, or the like that is not damaged at the melting temperature of the matrix metal is used.

(A) is a schematic diagram of the fiber structure before impregnating resin, (b) is a schematic cross section of the fiber structure of the area | region where the continuous fiber is not cut | disconnected. (A) is a schematic diagram which shows the arrangement state of x thread layer, (b) is a schematic diagram which shows the arrangement state of y thread layer. The schematic diagram of a fiber reinforced composite material.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fiber structure, 4 ... x yarn layer as a yarn layer, 4a ... x yarn as a fiber bundle which consists of continuous fibers, 5 ... y yarn layer as a yarn layer, 5a ... y as fiber bundles which consist of continuous fibers Yarn, 6 ... laminated fiber group, 7 ... thickness direction yarn as binding yarn, 10 ... fiber reinforced composite material.

Claims (5)

Fiber bundles of continuous fibers are bonded with a binding yarn made of continuous fibers arranged in the thickness direction of the laminated fiber group on the entire surface of at least biaxially oriented laminated fiber group to form a fibrous structure, the fibers A plurality of through holes penetrating in the thickness direction of the laminated fiber group are formed in a partial region of the structure, and the continuous fibers constituting the laminated fiber group and the continuous fibers constituting the binding yarn are cut by the through holes. the fibrous structure that is, a fiber reinforced composite material impregnated with a matrix, deformed region continuous fibers and continuous fibers that make up the binding yarn constituting the front Symbol laminated fiber group is cleaved Fiber reinforced composites. The fiber-reinforced composite material according to claim 1, wherein the binding yarns are uniformly arranged on the entire surface of the laminated fiber group. The binding yarn is folded at one surface of the laminated fiber group to form a U-shaped loop, and a retaining yarn made of continuous fibers is inserted so as to pass through the loop. Item 3. A fiber-reinforced composite material according to Item 2. The fiber reinforced composite material according to any one of claims 1 to 3, wherein continuous fibers are not cut in a region of at least one of both ends of the length direction and the width direction of the fiber structure. The fiber reinforced composite material according to any one of claims 1 to 4, wherein the through hole is formed by inserting and retracting a cutting needle a plurality of times in the thickness direction of the laminated fiber group.

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