JPH0415468Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a resin reinforcing base material suitable for molding a carbon fiber reinforced resin into a pipe shape, a ring shape, etc.

Conventional technology Pipe-shaped or ring-shaped fiber-reinforced resins (hereinafter referred to as FRP) have conventionally been produced by winding a reinforcing fiber prepreg sheet around a mandrel, applying pressure and heating to harden the resin, or It is formed by a method such as winding a reinforcing fiber fabric, etc., impregnating the fabric with resin, and hardening the resin by applying pressure and heating. however,
The FRP formed in this way has reinforcing fibers that
Although it exists in the in-plane direction, it does not exist at all in the thickness direction, so there is a problem that interlaminar strength, especially interlaminar peel strength and interlaminar shear strength, is low.

On the other hand, Japanese Utility Model Publication No. 47-37027 discloses that a wound body made of a woven or non-woven fabric of reinforcing fibers is wound around a tubular mandrel, and a sewing thread having a strength greater than that of the reinforcing fibers constituting the woven fabric or non-woven fabric is attached to the mandrel. An FRP pipe is described in which the wound body is impregnated with a resin after being sequentially penetrated in the tangential direction, and the resin is hardened by applying pressure and heating. When looking at this FRP pipe as a whole, the high-strength sewing thread extends in the thickness direction, so the interlayer strength is improved compared to a pipe that does not use sewing thread. However, the degree is so small that it hardly matters.

In other words, FRP exhibits high strength in the direction of the fiber axis of the reinforcing fibers, but the strength rapidly decreases as it moves away from the fiber axis (at an angle to the fiber axis). It is a material with extremely high properties. Therefore, as mentioned above,
In order to effectively improve the interlaminar strength of an FRP pipe, it is most preferable to extend the suture thread correctly in the radial direction of the pipe. Since the sewing thread is passed through the FRP pipe in the radial direction, the sewing thread has a large angle with respect to the radial direction of the FRP pipe.
Since the properties of the sewing thread are not fully utilized, the effect of improving interlayer strength is small. However, the interlaminar strength can be improved by increasing the thickness of the sewing thread or increasing the sewing density. However, in this case, the reinforcing fibers are cut or damaged when passing the suture through the tube, which in turn reduces the strength in the in-plane direction of the tube, and in the end, the strength of the FRP tube as a whole does not become very high. Furthermore, when a thick sewing thread is used, the arrangement of the reinforcing fibers is likely to be disturbed by the thread, which may reduce the in-plane strength.

Damage to reinforcing fibers is likely to occur even when using thin sewing threads. That is, when the sewing thread is sequentially passed through the mandrel in the tangential direction, at the sewing start end, the thread having a length equal to the thread length used for suturing passes through the wound body. Therefore, the closer to the sewing start end, the more opportunities there are for the sewing thread to rub against the reinforcing fibers constituting the woven or nonwoven fabric, and the reinforcing fibers are more likely to be damaged.

In addition, if you try to pass the sewing thread sequentially in the tangential direction of the mandrel, you have to do it manually, which not only takes a lot of effort, but also makes it difficult to suture with a uniform force manually, and the thickness of the mandrel increases. There is also the problem that highly reliable FRP cannot be obtained due to non-uniformity and disordered arrangement of reinforcing fibers.

Problems to be solved by the invention The purpose of this invention is to solve the above-mentioned problems of the prior art, and to create carbon fiber-reinforced pipe-shaped, ring-shaped, etc. Resin (hereinafter referred to as carbon fiber reinforced resin, CFRP)
The purpose of the present invention is to provide a reinforced base material that can be molded.

Means for Solving the Problems In order to achieve the above-mentioned object, in this invention, a hollow wound body formed by winding a plurality of carbon fiber fabrics is sewn together with sewing thread, and the fabric is made of satin. The thread is made of (a) high strength, high modulus reinforcing fiber, and (b) has a greater elongation at break than the carbon fiber. -15° with respect to the direction perpendicular to the surface of the above-mentioned wound body.
It extends in the thickness direction of the wound body at an angle within the range of ~+15°, and the above-mentioned suturing is performed by a single chain stitch, and b is performed in the circumferential direction of the wound body. Provided is a reinforcing base material for carbon fiber reinforced resin characterized by the following.

To explain the reinforcing base material of this invention in more detail based on one embodiment thereof, in FIG. , it has a hollow wound body 4 formed by spirally wound. The fabric 1 is wound so that its warp is in the longitudinal direction of the reinforcing base material 5, and the weft is therefore in the circumferential direction, while the fabric 2 is wound so that its warp and weft are in the longitudinal direction. They are wound in directions of +45° and -45°, respectively. The winding start end and the winding end end of the fabrics 1 and 2 are slightly shifted from each other so as not to cause significant unevenness on the reinforcing base material 5 at that portion.

The thread 3 extends in the circumferential direction of the wound body 4 while repeatedly penetrating the wound body 4 from the inner surface to the outer surface and from the outer surface to the inner surface. 5 are engaged at equal pitches in the longitudinal direction, and the wound body 4 is sewn together.

In the above, the fabric is made of satin fabric. In other words, since the satin tissue is relatively thick per sheet and has a relatively low slippage resistance, there is less worry about cutting or damaging the carbon fibers during suturing, so it is especially suitable for thick CFRP. This is effective when you want to mold. Note that the fabric may be a prepreg impregnated with a thermosetting resin such as a B-stage epoxy resin, unsaturated polyester resin, phenolic resin, or polyimide resin.

The reinforcing fibers constituting the fabric are carbon fibers as described above. Carbon fiber is made of multifilaments, and in order to improve resin impregnation when molding CFRP and to increase the volume content in CFRP, the wound body is sewn together. It is preferable that the number of twists is small in order to prevent cutting or damage caused by the sewing thread during threading. That is, since carbon fiber has an extremely high modulus of elasticity and a low elongation at break, it is very weak against bending force, so the number of twists is preferably small, and it is most preferable that the fiber is substantially untwisted.

The number of turns of the fabric can be selected depending on the desired thickness of CFRP. However, if it becomes extremely thick, it becomes difficult to suture with sewing thread, so it is preferable to set the number of turns so that the thickness is 40 mm or less.

The woven fabric is wound so that the wound body has in-plane pseudo-isotropy. In order to achieve in-plane pseudo-isotropy, the first
As shown in the figure, a combination of angles of 0°, ±45°, and 90° is most preferred.

The sewing thread not only stitches together the wound fabric, but also acts to improve the interlaminar strength of the reinforcing base material and, ultimately, the CFRP. However, the sewing thread
The reinforcing fibers are preferably made of multifilaments with a single fiber diameter of 3 to 15 μm, but because they have to be bent significantly, the stress applied to the reinforcing base material is concentrated at the bent portions, causing the fabric to deteriorate. In order to prevent the sewing thread from breaking before the constituent carbon fibers, the reinforcing base material will not break from that part.
It must have a greater elongation at break than the carbon fibers that make up the fabric. The elongation at break is preferably 1.5 times or more that of the carbon fibers constituting the fabric. In addition, as a sewing thread,
Among reinforcing fibers such as carbon fibers, glass fibers, organic high modulus fibers (for example, polyaramid fibers), those satisfying the above-mentioned elongation at break are selected and used.

Further, the sewing thread preferably has a ply twist of 30 times/m or more in order to prevent single thread breakage and thread cracking during sewing. However, if the number of twists is too large, the cross-sectional shape will become round.
Since the volume content of carbon fibers when molding CFRP becomes low, it is preferably 70 times/m or less.

Furthermore, if the number of turns of the fabric is small, the thickness of the sewing thread will be the same as the thickness of the reinforcing base material, and thus the CFRP.
Since this will affect the carbon fiber content of the material, it is preferable to use material with a cross-sectional area of about 0.008 to 0.12 mm ² and to increase the sewing density. A more preferred cross-sectional area is ^{0.008-0.06mm2}
It is. However, if the number of windings is large, approximately 5 times or more, the effect of sewing thread is small, so use a relatively thick thread with a cross-sectional area of 0.05 to 0.35 ^mm2 , preferably 0.05 to 0.25 ^mm2 , and reduce the sewing density. It is preferable to lower the

The wound body is sutured using a single chain stitch. In other words, in single chain stitch, unlike lock stitch, the upper thread and bobbin thread intersect with each other inside the wound body.
Does not bend 180°. Therefore, it becomes possible to fully utilize the strength, elastic modulus, and other properties of the sewing thread, and the effect of improving the interlayer strength is significant. Therefore, in order to express the characteristics of the sewing thread as it is and effectively improve the interlayer strength of the reinforcing base material and eventually the CFRP, the sewing thread must be adjusted at an angle of -15° to +15° with respect to the direction perpendicular to the surface of the wound body. It must extend at an angle within °. Preferably it is 0°.

If the stitching of the wound body with sewing thread is too strong, it may disturb the arrangement of the carbon fibers that make up the fabric, make it difficult to impregnate with resin later, or cause resin accumulation at the stitched part when CFRP is molded. On the other hand, if it is too weak, the sewing thread will loosen in the thickness direction when CFRP is formed, reducing the effect of improving interlaminar strength.
It is preferable to set the thickness to about 0.9 to 1.1 times the molded thickness of CFRP.

Since the reinforcing effect in the circumferential direction is improved, it is preferable that the sewing thread extends in a ring shape in the circumferential direction of the wound body, as shown in Fig. 1, or in a spiral shape in the longitudinal direction. It may extend to In the longitudinal direction, the pitch may be equal or random. In any case, the stitching is performed in the circumferential direction of the wound body.

In the embodiment described above, the case where the reinforcing base material is in the shape of a pipe with the same thickness has been described, but the reinforcing base material of this invention can have various shapes.

That is, the reinforcing base material may have a ring shape, a cone shape as shown in FIG. 2, a deformed pipe shape as shown in FIG. 3, etc., for example. Furthermore, by partially changing the number of turns of the fabric, it is possible to make only a specific portion in the longitudinal direction thicker, as shown in FIG. Furthermore, by inserting pieces of fabric only in specific portions when winding the fabric, it is possible to obtain a reinforcing base material that is thick only in specific circumferential portions, as shown in FIG. Note that the cross-sectional shape of the reinforcing base material does not have to be circular as shown in FIGS. 1 to 5, and may be rectangular or other shapes.

The reinforcing base material of this invention is manufactured, for example, as follows.

That is, a carbon fiber fabric or its prepreg,
Alternatively, they are stacked one on top of the other so that the carbon fibers are oriented in a desired direction, then wound, the core is removed, and a single chainstitch is performed using a sewing machine to sew. It is also possible to use a core body with slits in the sewing direction, and to remove the core body after stitching is performed at the slits. In addition, if the fabric is prepreg, a release agent such as silicone is applied to the core.
It is preferable to make it easy to remove the core. Furthermore, in the case of prepreg, the carbon fibers that make up the fabric are difficult to move due to the B-stage thermosetting resin, and when a sewing machine needle penetrates, the carbon fibers have an area equivalent to the cross-sectional area of the fabric. Since there is a possibility that the carbon fibers may be cut or damaged, it is also preferable to heat the prepreg or the like below the gelation temperature of the thermosetting resin to lower the viscosity of the resin and make the carbon fibers easier to move. Additionally, if the sewing thread is impregnated with the same thermosetting resin as the prepreg and made into a prepreg, it will make sewing a little more difficult, but it will make the resin distribution more uniform when CFRP is molded. This reduces voids and makes it possible to obtain stronger CFRP.

To mold CFRP using the reinforcing base material of this invention, a mandrel with the desired cross-sectional shape is used. If the fabric is not prepreg, the reinforcing base material is fitted into the mandrel and a resin injecting method is used. I will do it. When the fabric is a prepreg, the reinforcing base material is fitted into a mandrel and molded using an autoclave, or by a so-called tape wrapping method in which a heat-shrinkable film is wrapped and heated.

Effects of the invention In the reinforcing base material of this invention, the stitching thread that stitches together the hollow wound body made of wound carbon fiber fabric is in the range of −15° to +15° with respect to the direction perpendicular to the surface of the wound body. The suture extends at an angle within the range of
Since the stitching is carried out using a single chain stitch in which the sewing thread does not bend inside the wound body, the strength, elasticity, and other properties of the sewing thread can be fully expressed. Therefore, interlaminar strength,
In particular, it becomes possible to obtain CFRP with high interlaminar peel strength and interlaminar shear strength. Moreover, the sewing thread
Since it has a greater elongation at break than the carbon fibers that make up the fabric, the sewing thread will not break before the carbon fibers, and the properties of carbon fibers can be utilized almost as they are. Therefore, the in-plane strength of CFRP is greatly improved.
In addition, in-plane strength allows the characteristics of the sewing thread to be fully utilized, allowing the thickness to be made thinner, and there is no need to worry about cutting or damaging the carbon fibers that make up the fabric during sewing. In addition to being less,
As the woven fabric is relatively thick per piece and has relatively low shear resistance, the satin woven fabric is less worried about cutting or damaging the carbon fibers during stitching, making it even more durable. improves.
Furthermore, since the wound body is sewn using a single chainstitch, a sewing machine can be used and there is no need for manual labor, which not only simplifies manufacturing, but also ensures uniform stitching force, making it possible to use highly reliable CFRP. be able to obtain it.

The reinforcing base material of this invention can be used for various purposes.
It can be used when molding CFRP, but because CFRP has high mechanical strength, especially interlaminar peel strength and interlaminar shear strength, and is highly reliable, it is being used as a primary structural material for aerospace applications. Particularly suitable for forming pipes, mechanical elements, propeller shafts, wheels, rims of automobiles, motorcycles, bicycles, etc., various high-speed rotating bodies such as pressure vessels, rotating bodies of centrifuges, seal rings, etc. It is.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view showing one embodiment of the reinforcing base material of this invention, and Figs. 2 to 5 show reinforcing base materials of this invention, respectively different embodiments from those shown in Fig. 1 above. It is a schematic perspective view. DESCRIPTION OF SYMBOLS 1...Carbon fiber satin fabric, 2...Carbon fiber satin fabric, 3...Sewing thread, 4...Wound body, 5...Reinforcement base material.

Claims (1)

[Claims for Utility Model Registration] A hollow wound body formed by winding a plurality of carbon fiber fabrics is sewn together with sewing thread, the fabric is made of satin fabric, and the wound body has an in-plane pseudo-like structure. The sewing thread is wound in a direction perpendicular to the plane of the wound body, (i) is made of high strength, high modulus reinforcing fiber, (b) has a greater elongation at break than the carbon fiber, and (c) is perpendicular to the surface of the wound body. −15° to the direction
It extends in the thickness direction of the wound body at an angle within the range of ~+15°, and the above-mentioned suturing is performed by a single chain stitch, and b is performed in the circumferential direction of the wound body. , A reinforcing base material for carbon fiber reinforced resin.