JP2004034592A - Method for manufacturing fiber reinforced composite material and fiber structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a three-dimensional fiber reinforced composite material at a low cost. <P>SOLUTION: An x yarn layer 4 and a y yarn layer 5 formed by arranging continuous fibers in one direction are mutually multi-laminated and form a laminated fiber group 6 in biaxial orientation. The fiber structure 1 is provided with a non-cut region 2 in which continuous fibers of the laminated fiber group 6 combined by yarns 7 in the thickness direction and pulling-out prevention yarns 8 are not cut, and a cut region 3 in which the continuous fibers are cut. The cut region 3 is disposed at the part where deformation is necessary when forming to a product shape. Also, both end parts of the fiber structure 1 are the non-cut region 2. The cut region 3 is apt to deform since the binding force is weak because a part of respective yarns is cut. Accordingly, deformation at the time of forming is easy even when the three-dimensional fiber structure of the continuous fiber is used as a reinforcing material. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a fiber-reinforced composite material and a fiber structure.
[0002]
[Prior art]
Fiber-reinforced composite materials, particularly fiber-reinforced plastics, are lightweight and high-strength, and are widely used in automobiles as structural materials such as spoilers. The fibers used for the fiber-reinforced composite material include carbon fibers, glass fibers, polyaramid fibers and the like.
[0003]
The most frequently used fiber reinforced composites that use short fibers or long fibers that are not continuous fibers as reinforcements have broken fibers and their orientation is difficult to control. There is. In addition, fiber-reinforced composites that use a two-dimensional fiber structure that uses pre-cut fibers, such as non-woven fabrics using chopped fibers or woven fabrics using cut-off yarns, are fiber-reinforced composites using short fibers or long fibers. Higher strength than wood. However, the cutting step increases costs. When the thickness of the final product is large, a plurality of nonwoven fabrics or woven fabrics are used in a laminated state, so that the strength in the thickness direction is low and the bending strength is also low.
[0004]
When the thickness of the final product is large and high strength is required, 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.
[0005]
The fiber-reinforced composite material must be deformed into a part shape during molding. Conventionally, there is a method of partially fusing a coarse woven fabric with a thermoplastic resin in order to easily deform the two-dimensional fiber structure. In addition, Japanese Patent Application Laid-Open No. 8-337666 discloses a deep-drawn preform including a bidirectional woven fabric having a warp and a weft as reinforcing fibers. This preform has a thermoplastic polymer linearly and continuously or discontinuously attached to at least one of the warp yarn and the weft yarn, and the minimum crossing angle of the yarn extending in two directions of the reinforcing fabric is 20 to 40. Degree. However, in the case of using a woven fabric as a reinforcing material, there is a restriction even if the mesh is coarsened, so there is a limit to deformation, and yarns (fibers) having different arrangement directions interfere with each other, so that the fibers are arranged straight. However, it is difficult to increase the strength of the fiber-reinforced composite material.
[0006]
[Problems to be solved by the invention]
A three-dimensional fiber structure using continuous fibers is less likely to be deformed in accordance with the part shape than a two-dimensional fiber structure. Therefore, a three-dimensional fiber structure using continuous fibers has to be manufactured in advance in a shape that matches the product shape so as not to need to be deformed. However, in this case, a manufacturing apparatus, a jig, and the like for a fiber structure are required for each product shape, so that the cost is high.
[0007]
The present invention has been made in view of the above problems, and a first object of the present invention is to provide a method for producing a three-dimensional fiber reinforced composite material capable of producing a three-dimensional fiber reinforced composite material at low cost. A second object is to provide a fiber structure suitable for the manufacturing method.
[0008]
[Means for Solving the Problems]
In order to achieve the first object, the invention according to claim 1 forms a yarn layer by arranging fiber bundles composed of continuous fibers in one direction, and laminates the yarn layers to at least biaxial orientation. After forming a laminated fiber group of the laminated fiber group, after inserting the binding yarn in the thickness direction of the laminated fiber group on the entire surface of the laminated fiber group and binding the yarn layers, the fiber layer has a portion that requires deformation and an unnecessary portion. A part of the continuous fiber in the area of the part where the deformation is required of the laminated fiber group is cut to produce a fibrous structure, and then the fibrous structure is impregnated with a thermoplastic resin to form a plate-like material. And forming the composite to form a composite. Here, the term "yarn" does not only mean a twisted yarn, but also includes a fiber bundle (so-called roving) in which a large number of fibers are bundled and twisting is not substantially applied.
[0009]
According to the present invention, by cutting a part of the continuous fibers in a region of a portion requiring deformation in the entire surface of the laminated fiber group bonded by the bonding yarn, the binding force is reduced in the region. Therefore, even when a three-dimensional fiber structure of continuous fibers is used as a reinforcing material, deformation during molding becomes easy, and a fiber-reinforced composite material having a desired shape can be manufactured by press working or the like. Therefore, there is no need to manufacture a three-dimensional fiber structure having a shape that matches the product shape, and costs can be reduced.
[0010]
The invention according to claim 2, wherein the fiber bundle formed of continuous fibers is arranged in one direction to form a yarn layer, and the yarn layers are laminated to form at least a biaxially oriented laminated fiber group, and the laminated fiber After inserting the binding yarn in the thickness direction of the laminated fiber group on the entire surface of the group and bonding the yarn layers, the laminated fiber group having a portion requiring deformation and an unnecessary portion A part of the continuous fiber in the region is cut to produce a fibrous structure, and then the fibrous structure is put into a mold to obtain a product shape, and is impregnated and cured with a resin to form a composite material. Here, the curing of the resin includes not only the curing by a reaction such as thermosetting or ultraviolet curing, but also the hardening of the thermoplastic resin which has been softened or melted by heating and cooled by heating. That is, the resin may be a thermoplastic resin or a thermosetting resin. Accordingly, a thermosetting resin can be used, and a fiber-reinforced composite material having higher strength can be obtained.
[0011]
In order to attain the second object, the invention according to claim 3 is characterized in that a laminated fiber group in which a fiber bundle composed of continuous fibers is at least biaxially oriented has a thickness of the laminated fiber group on the entire surface of the laminated fiber group. The continuous fibers in some regions are cut by the bonding yarns arranged in the directions. Therefore, the restraining force is reduced in the region where the continuous fiber is cut, and the deformation is easy, and it can be suitably used in the manufacturing method of the first and second aspects of the present invention.
[0012]
According to a fourth aspect of the present invention, in the third aspect, the binding yarns are uniformly arranged on the entire surface of the laminated fiber group. Therefore, it is easy to manufacture the fibrous structure.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
An embodiment in which the present invention is embodied in the production of a fiber-reinforced composite material using a thermoplastic resin as a matrix resin will be described with reference to FIGS.
[0014]
First, the fiber structure will be described. As shown in FIG. 1B, x yarns 4a as a fiber bundle made 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 yarns 5a as a fiber bundle made of continuous fibers are arranged in one direction (the left and right direction in FIG. 1B) to form the y yarn layer 5. The x-yarn layer 4 and the y-yarn layer 5 are alternately laminated in a plurality of layers 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 in a U-shape on one surface (the lower surface in FIG. 1B) of the laminated fiber group 6, and the thickness direction yarn 7 is folded on the other surface (the upper surface in FIG. 1B). At the insertion position separated by the arrangement pitch of, and is continuously inserted into the laminated fiber group 6 again. The retaining yarn 8 is inserted into a portion where the thickness direction yarn 7 is folded back into a U-shape. The x-layer 4 and the y-layer 5 are joined by tightening the thickness direction thread 7 and the retaining thread 8. In the laminated fiber group 6 joined by the thickness direction yarn 7 and the retaining yarn 8, the x yarn 4a, the y yarn 5a, the thickness direction yarn 7, and a part of the retaining yarn 8 are cut in some regions. Thus, a cutting region 3 is formed.
[0015]
As shown in FIG. 1A, the fibrous structure 1 has a non-cut area where the x yarns 4a, the y yarns 5a, etc. of the laminated fiber group 6 joined by the thickness direction yarns 7 and the retaining yarns 8 are not cut. 2 and a cutting area 3 where the x yarn 4a, the 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. Both ends of the fibrous structure 1 are non-cut regions 2. Since a part of each of the yarns is cut in the cutting area 3, the cutting force is weaker than that in the non-cutting area 2 and is easily deformed.
[0016]
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. The 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 fibrous structure 1 is about 5 mm.
[0017]
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 9 is provided with a large number of pins 9b so as to surround the hole 9a. The pitch of the pins 9b is matched with the pitch of the x yarn 4a and the y yarn 5a.
[0018]
As shown in FIG. 2A, the x yarn 4a is folded in a state of being engaged with the pin 9b to form the x yarn layer 4 oriented in one direction. Next, as shown in FIG. 2B, the y yarn 5a is similarly folded back in a state of being engaged with the pin 9b, and is oriented in one direction orthogonal to the x yarn 4a to form the y yarn layer 5. . This is repeated a predetermined number of times to form the laminated fiber group 6. 2 (a) and 2 (b), the arrangement intervals of the x yarns 4a and the y yarns 5a are broadly illustrated. However, in practice, the x yarns 4a or the y yarns 5a arranged adjacent to each other are in contact with each other. Are arranged.
[0019]
Next, the thickness direction thread 7 is inserted into the laminated fiber group 6 by a method disclosed in, for example, JP-A-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 in the hole is inserted. The insertion needle is advanced and inserted until the hole of the insertion needle on which the thickness direction thread 7 is hooked penetrates the laminated fiber group 6. Thereafter, the insertion needle is withdrawn slightly. As a result, the thickness direction thread 7 is in a state of forming a U-shaped loop.
[0020]
Next, when a not-shown retaining thread needle passes through the U-shaped loop and reaches the end of the laminated fiber group 6, it stops. At this time, the retaining thread 8 is hooked on 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, the retaining thread 8 is tightened by the thickness direction thread 7, and the respective thread layers are joined. This process is performed uniformly over the entire surface of the laminated fiber group 6, and a fiber structure in which the yarn layers of the laminated fiber group 6 are joined by the thickness direction yarns 7 is manufactured.
[0021]
Next, a cutting needle attached in place of the insertion needle is inserted and retracted a plurality of times into a region of the fibrous structure which is a portion that needs to be deformed when forming into a desired product shape. The x yarn 4a, the y yarn 5a, the thickness direction yarn 7, and the retaining yarn 8 in the region are cut in accordance with the number of times the cutting needle has been inserted / retracted, and the cut region 3 is formed. Thus, the fibrous structure 1 composed of the non-cut area 2 and the cut area 3 is manufactured. However, not all areas of the fibrous structure 1 are cut areas 3.
[0022]
The fibrous 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 by a press molding machine, and cooled to obtain a fiber-reinforced composite material 10 in a product shape as shown in FIG.
[0023]
This embodiment has the following effects.
(1) The fiber structure 1 in which each of the yarn layers of the laminated fiber group 6 is bonded by the thickness direction yarn 7 and the fiber structure 1 in which a part of the continuous fiber is cut in the area where the deformation is required is used as the reinforcing material. A fiber-reinforced composite material is manufactured. Therefore, there is no need to manufacture a three-dimensional fiber structure having a shape that matches the product shape, and costs can be reduced.
[0024]
(2) The continuous fiber is cut by inserting and pulling back the cutting needle into the fiber structure in which each yarn layer of the laminated fiber group 6 is connected by the thickness direction yarn 7. Therefore, the production of the fibrous structure 1 is easy.
[0025]
(3) The cutting area 3 is formed by inserting and withdrawing the cutting needle. Therefore, the binding force of the cutting area 3 can be easily adjusted by the number of times of insertion / retraction.
(4) The cutting area 3 is formed by inserting / retracting a cutting needle attached in place of the insertion needle. Therefore, existing equipment can be used and manufacturing is easy.
[0026]
(5) Only the cutting region 3 has a reduced binding force, and the non-cutting region 2 is made of continuous fibers and has a binding force. Therefore, even when the fiber structure 1 is not impregnated with the resin, the handleability of the fiber structure 1 is good.
[0027]
(6) Non-cut areas 2 are provided at both ends of the fibrous structure 1. Therefore, even when the fiber structure 1 is not impregnated with the resin, the handleability of the fiber structure 1 is good.
[0028]
(7) The cutting area 3 which needs to be deformed has a reduced binding force. Therefore, the fibrous structure 1 is deformed in accordance with the component shape by the press working, and no wrinkles are generated.
[0029]
(8) Only the cutting region 3 where deformation is necessary has a reduced binding force, and the non-cutting region 2 is made of continuous fibers. Therefore, the strength as a fiber-reinforced composite material having a product shape and a three-dimensional fiber structure of continuous fibers as a reinforcing material is maintained.
[0030]
(Second embodiment)
Next, a second embodiment will be described. In this embodiment, the configuration and manufacturing method of the fibrous structure 1 are the same as those of the above-described 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 will be omitted.
[0031]
The fibrous structure 1 obtained according to the above embodiment is put into a molding die and closed. At this time, since the area of the portion that needs to be deformed is the cut area 3, the fibrous structure 1 is deformed according to the mold to have a product shape. Next, a thermosetting resin is injected and impregnated, and then heat-cured to obtain a fiber-reinforced composite material 10 having a product shape as shown in FIG. (RTM method: resin transfer molding method)
This embodiment has the following effects in addition to the effects similar to (1) to (8) of the above embodiment.
[0032]
(9) It can be molded using a thermosetting resin. Therefore, a fiber-reinforced composite material having higher strength than when a thermoplastic resin is used can be manufactured.
The embodiment is not limited to the above, and may be configured as follows, for example.
[0033]
○ The reinforcing fibers need not be carbon fibers. For example, glass fiber, polyaramid fiber, ceramic fiber and the like may be used.
The same fibers may not be 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 fiber of the x yarn 4a may be lower in strength than the fiber of the y yarn 5a in accordance with the physical properties required of the fiber reinforced composite material 10. In this case, the production cost can be reduced without making the fiber reinforced composite material 10 of excessive quality.
[0034]
The thickness direction yarns 7 need not 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 high binding force, and a region where the thickness direction yarns 7 are sparse has a low binding force. Therefore, the binding force can be adjusted.
[0035]
The laminated fiber group 6 only needs to be at least biaxially oriented, and has two types of yarn layers, an x yarn layer 4 composed of x yarns 4a and a y yarn layer 5 composed of y yarns 5a arranged orthogonally to each other. It does not need to be formed with For example, the laminated fiber group 6 may be formed of yarn layers in which the arranged yarns are not arranged orthogonally to each other.
[0036]
○ The laminated fiber group 6 may have three or more axes. For example, a bias yarn layer may be inserted according to the strength required for the product.
○ The fibrous structure need not be a flat plate. It may be a curved surface having a small curvature.
[0037]
O Without using the retaining thread 8, each thread layer may be joined by general sewing using only the thickness direction thread 7.
The thickness direction yarns 7 do not have to be arranged continuously from one end to the other end of the fibrous structure 1. Even if it is discontinuous, it is only necessary to penetrate and connect each yarn layer.
[0038]
In the case of manufacturing the fiber reinforced composite material 10, it is not limited to forming one fiber reinforced composite material 10 (product) with one fiber structure 1. A plurality of fibrous structures 1 may be arranged or stacked depending on the product shape or required performance.
[0039]
In order to form the cutting region 3, it is not necessary to use a cutting needle attached in place of the insertion needle. For example, needle punching may be performed in another step. In addition, a small blade that does not destroy the fibrous structure may be used instead of the needle.
[0040]
○ The first embodiment is not limited 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.
[0041]
The second embodiment is not limited to the RTM method. Any method may be used as long as the sheet-like fibrous structure 1 is impregnated with a thermosetting resin.
The matrix resin constituting the fiber reinforced composite material 10 of the second embodiment is not limited to a thermosetting resin, but may be a thermoplastic resin. In this case, heating after impregnating the resin is not required, and the resin may be naturally cooled.
[0042]
The matrix of the fiber reinforced composite material 10 may be other than resin, for example, metal. In this case, as the fibers constituting the fibrous structure 1, carbon fibers, ceramic fibers, and the like that are not damaged by the melting temperature of the matrix metal are used.
[0043]
The technical ideas (inventions) that can be grasped from the above embodiment will be described below. (1) In the invention according to claim 3 or 4, the continuous fibers are in a non-cut state in at least one of both end regions in the length direction and the width direction of the fibrous structure.
[0044]
(2) A fiber-reinforced composite material comprising the fiber structure according to claim 3 or 4 as a reinforcing material.
[0045]
【The invention's effect】
As described in detail above, according to the first and second aspects of the present invention, a three-dimensional fiber reinforced composite material can be manufactured at low cost. Further, the fiber structure according to the third and fourth aspects of the invention is suitable for the method for producing a fiber-reinforced composite material according to the first and second aspects.
[Brief description of the drawings]
FIG. 1A is a schematic diagram of a fiber structure before resin impregnation, and FIG. 1B is a schematic cross-sectional view of the fiber structure in a region where continuous fibers are not cut.
2A is a schematic diagram showing an arrangement state of an x yarn layer, and FIG. 2B is a schematic diagram showing an arrangement state of a y yarn layer.
FIG. 3 is a schematic view 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 composed of continuous fibers, 5 ... y yarn layer as a yarn layer, 5a ... y as fiber bundle composed of continuous fibers Yarn, 6 ... Laminated fiber group, 7 ... Thickness direction yarn as binding yarn, 10 ... Fiber reinforced composite material.

Claims (4)

A fiber bundle formed of continuous fibers is arranged in one direction to form a yarn layer, and the yarn layers are laminated to form a laminated fiber group of at least biaxial orientation. After inserting the binding yarn in the thickness direction and binding the yarn layers, the laminated fiber group having a portion requiring deformation and an unnecessary portion, a part of the continuous fibers in a region of a portion requiring deformation is removed. Cutting to produce a fibrous structure, then impregnating the fibrous structure with a thermoplastic resin to form a plate-like material, and molding the material to form a composite material, producing a fiber-reinforced composite material Method. A fiber bundle formed of continuous fibers is arranged in one direction to form a yarn layer, and the yarn layers are laminated to form a laminated fiber group of at least biaxial orientation. After inserting the binding yarn in the thickness direction and binding the yarn layers, the laminated fiber group having a portion requiring deformation and an unnecessary portion, a part of the continuous fibers in a region of a portion requiring deformation is removed. A method for producing a fiber-reinforced composite material, in which a fiber structure is manufactured by cutting, and then the fiber structure is put into a mold to obtain a product shape, and impregnated and cured with a resin to form a composite material. A laminated fiber group in which a fiber bundle composed of continuous fibers is at least biaxially oriented is bonded to the entire surface of the laminated fiber group by binding yarns arranged in the thickness direction of the laminated fiber group, and the continuous region A fibrous structure from which fibers have been cut. The fiber structure according to claim 3, wherein the binding yarns are uniformly arranged on the entire surface of the laminated fiber group.

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