JP3508429B2 - Fiber reinforced plastic tubular body - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubular body made of fiber reinforced plastic, and particularly used for golf club shafts, badminton racket shafts and other sports equipment because it is lightweight and has excellent resistance to torsional forces. A tubular body suitable for being processed.

[0002]

2. Description of the Related Art In recent years, tubular bodies made of fiber reinforced plastic having excellent characteristics such as light weight, high strength and high elasticity have been used.
It is used in various applications such as golf club shafts, fishing rods and other sports equipment, drive shafts, rolls and other general industrial applications.

A portion containing reinforcing fibers oriented at an angle of 20 ° to 75 ° with respect to the main axis of the tubular body for the purpose of providing these fiber-reinforced plastic tubular bodies with a proof stress against torsional force, that is, a torsional strength. That is, the bias layer is arranged.

As a method for molding such a fiber-reinforced plastic tubular body, a prepreg is cut into a predetermined shape,
The sheet winding method, in which a core metal is wound and molded, is widely used. This sheet wind method is easy to control the orientation and content of the reinforcing fibers and has a high degree of freedom in the design of the tubular body, and that a smooth and high-quality tubular body can be obtained,
It has features not found in other molding methods, such as easy voidless molding.

However, in this sheet winding method, since the prepreg cut into a predetermined shape is wound, a step is formed in the bias layer corresponding to the winding start position and the winding end position. When the winding start position is in contact with the core metal, there is no step in the outer shape, but this is the same as the step of the bias layer due to the resin accumulation. (Hereinafter, such a case is also referred to as a step.) Since the reinforcing fiber is cut at this step, and the bending of the reinforcing fiber occurs around the step, the strength is low.

In the sheet winding method, the bias layer is usually applied to the tubular body n times, rarely (n +), in order to make the physical properties of the tubular body symmetrical and to make the wall thickness of the tubular body uniform.
0.5) Adjust the size of cutting out the prepreg so that it is wound one time (n is a positive integer). However, when winding n times, two steps corresponding to the winding start position and the winding end position overlap, and when winding (n + 0.5) times, when two or more bias layers are arranged, another Often overlaps with the step due to prepreg. That is, in the conventional tubular body, the steps of the bias layer are not dispersed,
Since the concentration is concentrated, when a twisting force is applied to the tubular body, breakage easily occurs from such a portion, and as a result, the twisting strength of the tubular body becomes insufficient.

[0007] To solve these problems,
Japanese Patent No. 373 describes an ultra-thin prepreg that can be easily wound uniformly and have a relatively small step. However, the production of this ultra-thin prepreg requires a special process for uniformly expanding the reinforcing fibers, so that it is expensive and the types of reinforcing fibers that can be applied are limited. Therefore, there is a problem that the cost of the tubular body using this increases and the degree of freedom in designing the tubular body decreases.

[0008] In addition, Japanese Patent Laid-Open No. 7-39611 discloses that
Described is the method of forming the inner bias layer by the so-called filament winding method to eliminate the step of the bias layer and forming the other layers on the outside by the sheet winding method to achieve design flexibility and smooth the surface. Has been done. However, this method requires both the filament winding method and the sheet winding method, and the manufacturing time becomes long, resulting in a significant increase in cost. Further, there is also a problem that voids are likely to be formed in the inner bias layer formed by the filament winding method, and the torsional strength may not be increased.

Further, JP-A-4-218179 and JP-A-5-169265 disclose a method of adding a reinforcing layer against torsion to a tubular body, and JP-A-6-114131 discloses. A method of symmetry of tubular body construction is described. However, these methods increase the weight of the tubular body, increase the number of times the prepreg is wound, and increase the cost.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a tubular body having a bias layer formed by a sheet winding method or the like without increasing weight and cost. SUMMARY OF THE INVENTION It is an object of the present invention to provide a tubular body made of fiber reinforced plastic having a high torsional strength which has never been obtained.

[0011]

The present invention has the following constitution in order to achieve the above object.

[0012]

[0013] That is, the winding angle of the reinforcing fibers to (1) the tubular body spindle 20-7
In the range of 5 ° and together the bias layer is of opposite directions
In the tubular body made of fiber reinforced plastic according to, the tubular body has a winding start position of the two forward and reverse bias layers.
They are shifted by substantially half a turn, and the number of windings of the reinforcing fiber in the bias layer is (n + 0.1) to (n + 0.
A tubular body made of reinforced fiber plastic having a portion within the range of 4) (where n is a positive integer).

[0014]

(2) Two unidirectional prepregs cut out in a desired shape are in a range of 20 to 75 ° with respect to the main axis of the cored bar.
Wrap in both directions in the enclosure, then cure
By decoreing, two layers of windings with different winding angles
Method for producing fiber-reinforced plastic tubular body having ass layer
In the method, the unidirectional prepreg is applied to the core metal in both forward and reverse
When winding in each direction, start winding each prepreg
And the number of windings of the unidirectional prepreg in the bias layer is (n
+0.1) to (n + 0.4). A method for producing a reinforced fiber plastic tubular body, wherein n is a positive integer.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The tubular body of the present invention has a portion where the winding angle of the reinforcing fiber with respect to the main axis is within the range of 20 ° to 75 °, that is, the bias layer. The winding angle of the reinforcing fiber with respect to the main axis is the absolute value of the angle formed by the plane including the main axis and the reinforcing fiber passing through the plane.

The reinforcing fibers of the bias layer are subjected to tensile or compressive forces when the tubular body is subjected to torsional forces. Reinforcing fibers having a winding angle with respect to the main axis of less than 20 ° or more than 75 ° do not significantly contribute to the torsional strength of the tubular body because the tubular body does not receive a large force when subjected to a torsional force.

[0018]

Further, the tubular body of the present invention has the above-mentioned bias layer.
In addition to the characteristics of the winding angle of the
The start position is offset by a substantial half turn, and the bias layer
The number of windings of the reinforcing fiber in each is (n + 0.1) to
It has a portion within the range of (n + 0.4). Where n
Is a positive integer. When the number of turns approaches n, the two steps approach each other and the torsional strength decreases. When the number of turns approaches (n + 0.5), the steps approach the steps of other bias layers and the torsional strength decreases. The weight of the body increases.

That is, the number of turns is n and (n + 0.
5) Ri avoided, by the number of windings that is the conventional speak halfway, has a not high torsional strength conventional, yet lightweight tubular body is provided. Further, the symmetry of physical properties and the uniformity of wall thickness of the tubular body are hardly affected by the number of windings.

The number of turns of the bias layer is (n + 0.2) to
Within the range of (n + 0.3), the steps of the bias layer are more likely to be evenly distributed, the torsional strength of the tubular body becomes higher, the weight of the tubular body becomes lighter, and the torsional strength per weight is increased. Can be higher.

The winding angle of the reinforcing fiber is preferably in the range of 40 to 50 ° in order to make the bias layer bear more torsional force and to enhance the effect of the present invention.
More preferably, it is around 5 °.

Examples of the reinforcing fiber of the bias layer include carbon fiber including graphite fiber, glass fiber, aramid fiber, boron fiber, metal fiber and the like. In order to form a lightweight and high strength tubular body, carbon fiber is used. preferable.

Further, in order to form a tubular body having high rigidity against torsional force, it is preferable that the reinforcing fiber of the bias layer has an elastic modulus of at least 350 GPa.

The effect of improving the torsional strength of the tubular body of the present invention is more remarkable when the number of bias layers is larger than the thickness of the tubular body. Specifically, the total thickness of the bias layer is preferably at least 10% of the wall thickness of the tubular body.

As the matrix resin of the fiber-reinforced plastic forming the tubular body, various thermosetting resins and thermoplastic resins such as epoxy resin, phenol resin, polyester resin, vinyl ester resin can be used. Of these, an epoxy resin that is easy to mold and has excellent physical properties is preferable.

The fiber content of the bias layer is preferably 40 to 85% by volume, more preferably 55 to 80% by volume, from the viewpoint of ease of molding and the torsional strength of the tubular body. Further, the void content of the bias layer is preferably less than 5% by volume, preferably 3% by volume, in view of the torsional strength of the tubular body.
It is preferably less than 1%, more preferably less than 1% by volume.

By providing a layer containing reinforcing fibers in various directions in addition to the bias layer, the tubular body can be provided with various performances. In order to provide rigidity and strength against bending force, a so-called straight layer containing reinforcing fibers having a winding angle of not more than 10 ° may be arranged, and a winding angle of 75 to 90 with respect to crushing force from the side. A hoop layer containing reinforcing fibers in the range of ° may be arranged.

The tubular body of the present invention has both two bias layers in which the winding angles of the reinforcing fibers are in both the forward and reverse directions.
It Here, both the forward and reverse directions refer to two directions having a right-handed thread and a left-handed thread with respect to the main axis of the tubular body. In this case, it is particularly preferable that the two bias layers overlap each other and the steps are evenly dispersed as shown in FIG.

The tubular body of the present invention has an effect of increasing the torsional strength when it is a thin-walled tubular body whose wall thickness does not exceed 2 mm or a thin tubular body whose external shape does not exceed 20 mm. Is especially large.

Since the tubular body of the present invention is lightweight and has excellent torsional strength, it is particularly suitable for use in shafts of golf clubs, badminton rackets, and sports equipment parts such as ski poles.

Torsional fracture of the golf club shaft is
It often occurs in the part with the smallest outer shape except for the tip reinforcing part. Therefore, it is preferable that such a portion has the configuration of the present invention. The tip reinforcing portion means a portion thicker than other portions in order to reinforce the small diameter portion at the tip of the golf shaft.

According to the present invention, it is possible to obtain a golf club shaft which has a sufficient torsional strength even if the overall weight is less than 50 g.

In order to produce the tubular body of the present invention, a prepreg cut into a predetermined shape is wound around a core metal, wrapped with a wrapping tape, molded in a curing oven, and then decoreed to remove the wrapping tape. The sheet wind method can be applied. The number of turns of the unidirectional prepreg when the unidirectional prepreg is wound to form the bias layer.
There (n + 0.1) ~ (n + 0.4) Ru wound to be in the range of. The number of windings can be easily adjusted by changing the size of cutting out the prepreg, and the other steps can be performed in the same manner as the conventional sheet winding method.
There is no increase in costs associated with equipment and process changes.

[0035] That is, in order to produce a tubular body as shown in FIG. 1, with winding two sheets of unidirectional prepreg is winding angle of the reinforcing fibers were overlaid so that the forward and reverse directions to the core
It At this time, in order to disperse the step due to two prepregs as in FIG. 1, as the winding end position are offset from each other, Ru wound from overlapping the prepreg being shifted by a length corresponding to the core half round.

[0036]

【Example】

Example 1 Unidirectional prepreg A (prepreg basis weight: 175 g / m 2) made of carbon fiber and epoxy resin for a bias layer
² , fiber content: 67% by weight, fiber tensile modulus: 436
Two pieces of GPa) were cut into a rectangle having a length of 1000 mm and a width of 70 mm so that the fiber direction was 45 ° with respect to the longitudinal direction. The two sheets were bonded so that the fiber directions intersect each other and shifted in the lateral direction by 16 mm (corresponding to half the circumference of the core metal). Next, the pasted prepreg was wound around a release-treated stainless steel core having an outer diameter of 10 mm and a length of 1400 mm so that the longitudinal direction of the prepreg and the main shaft of the core were aligned.

On top of that, a unidirectional prepreg B (prepreg basis weight: 225 g /
m ² , fiber content: 67% by weight, fiber tensile modulus: 29
4GPa) 100 so that the direction of the fibers is the longitudinal direction.
A piece cut into a rectangle of 0 mm × 74 mm in width was wound so that the longitudinal direction of the prepreg and the main shaft of the core bar were aligned.

Next, a wrapping tape for sheet wind molding is wound by a predetermined method, and the temperature is set to 13 in a curing furnace.
Molded at 0 ° C. for 2 hours.

After molding, the cored bar was decoreed and the wrapping tape was removed to obtain a fiber-reinforced plastic tubular body.

When the cross section of this tubular body was polished and observed by an optical microscope, the number of windings of the bias layer by one prepreg A was 2.13.

The weight of this tubular body per 1 m is 4
It was 1.2 g.

As a result of a twist test of this tubular body with a gauge length of 300 mm, the twist strength (product of torque and rotation angle at break) is 880 Nm °, and the twist strength per 1 m weight is 21.4 Nm ° m. / G.

Example 2 A fiber-reinforced plastic tubular body was obtained in the same manner as in Example 1 except that the prepreg A was cut into a rectangle having a width of 73 mm.

When the cross section of this tubular body was polished and observed with an optical microscope, the number of turns of the bias layer by one prepreg A was 2.20.

The weight of this tubular body per meter is 4
It was 2.6 g.

As a result of a twist test of this tubular body with a gauge length of 300 mm, the twist strength (product of torque and rotation angle at break) was 1120 Nm °, and the twist strength per 1 m weight was 26.3 Nm ° m. / G.

Example 3 A fiber-reinforced plastic tubular body was obtained in the same manner as in Example 1 except that the prepreg A was cut into a rectangle having a width of 78 mm.

When the cross section of this tubular body was polished and observed with an optical microscope, the number of windings of the bias layer by one prepreg A was 2.38.

The weight of this tubular body per meter is 4
It was 4.0 g.

As a result of a twist test of this tubular body with a gauge length of 300 mm, the twist strength (product of torque and rotation angle at break) is 1120 Nm °, and the twist strength per 1 m weight is 25.5 Nm ° m. / G.

Comparative Example 1 A fiber-reinforced plastic tubular body was obtained in the same manner as in Example 1 except that the prepreg A was cut into a rectangle having a width of 66 mm.

When the cross section of this tubular body was polished and observed with an optical microscope, the number of turns of the bias layer by one prepreg A was exactly 2.

Further, the weight of this tubular body per 1 m in length is 3
It was 9.8 g.

As a result of a twist test of this tubular body with a gauge length of 300 mm, the twist strength (product of torque and rotation angle at break) was 710 Nm °, and the twist strength per 1 m weight was 17.8 Nm ° m. / G.

Comparative Example 2 A fiber-reinforced plastic tubular body was obtained in the same manner as in Example 1 except that the prepreg A was cut into a rectangle having a width of 83 mm.

When the cross section of this tubular body was polished and observed with an optical microscope, the number of turns of the bias layer by one prepreg A was just 2.5.

The weight of this tubular body per 1 m is 4
It was 5.7 g.

As a result of a torsion test of this tubular body with a gauge length of 300 mm, the torsional strength (the product of the torque at the time of breaking and the rotation angle) was 950 Nm °, and the torsional strength per 1 m weight was 20.8 Nm ° m. / G.

[0059]

The fiber-reinforced plastic tubular body of the present invention has a reinforcing fiber winding angle of 20 to 75 with respect to the main axis of the tubular body.
Having a bias layer in the range of ° and in both forward and reverse directions
At the same time, the winding start position of the two forward and reverse bias layers is
It is substantially offset by half a circle, and the bias layer
The number of windings of the synthetic fiber is (n + 0.1) to (n + 0.
By having the portion within the range of 4), the steps of the bias layer are appropriately dispersed . Therefore, it has a high torsional strength that has never been seen before ( n is a positive integer) with almost no increase in weight or cost.

The tubular body of the present invention is particularly suitable for use as a golf club shaft or a badminton racket shaft because it is lightweight and has high torsional strength.

[Brief description of drawings]

FIG. 1 is a view showing a cross section of a tubular body according to an embodiment of the present invention.

[Explanation of symbols]

1: Bias layer (forward direction) 2: Bias layer (reverse direction) 3: Bias layer step (winding start position) 4: Bias layer step (winding end position) 5: Resin pool

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 B32B 11/16 B32B 15/08-15/14 C08J 5/04-5/10 C08J 5 / 24 B29C 70/00-70/88

Claims (13)

(57) [Claims] 1. The winding angle of the reinforcing fiber with respect to the main axis of the tubular body is 2.
A fiber-reinforced plastic tubular body having both bias layers in the range of 0 to 75 ° in both forward and reverse directions , wherein the tubular body has a winding start position of the two forward and reverse bias layers.
And the number of windings of the reinforcing fiber in the bias layer is (n + 0.1) to (n +).
0.4) A tubular body made of reinforced fiber plastic, wherein n has a positive integer. 2. The number of windings is (n + 0.2) to (n + 0.3).
The reinforced fiber plastic tubular body according to claim 1 , wherein the tubular body is in the range of 3. The number of windings of the reinforcing fiber of the bias layer is 40-5.
Characterized in that in the range of 0 ° claim 1 or 2
A tubular body made of reinforced fiber plastic according to 1. 4. A reinforced fiber plastic tubular body according to any one of claims 1 to 3, the reinforcing fiber of the bias layer is characterized in that it is a carbon fiber. 5. The winding angle of the reinforcing fiber with respect to the main axis of the tubular body is 1.
Reinforcing fiber plastic tubular body according to any one of claims 1 to 4, characterized in that it further comprises a straight layer containing reinforcing fibers not exceeding 0 °. 6. reinforcing fibers plastic tubular body according to any one of claims 1 to 5, the thickness of the portion is characterized in that it does not exceed 2 mm. 7. A reinforced fiber plastic tubular body according to any one of claims 1 to 6, the outer shape of the portion is characterized in that it does not exceed 20 mm. 8. A golf club shaft comprising the reinforced fiber plastic tubular body according to any one of claims 1 to 7 . 9. The golf club shaft according to claim 8 , wherein the portion is located at a portion having the smallest outer diameter except for the tip reinforcing portion. Golf club shaft according to claim 8 or 9 10. The overall weight is characterized in that it does not exceed 50 g. 11. A badminton racket shaft comprising the reinforced fiber plastic tubular body according to any one of claims 1 to 7 . 12. Two unidirectional prepregs cut into a desired shape within a range of 20 to 75 ° with respect to a main axis of a cored bar.
Wrap in both forward and backward directions, then cure and decore
The bias of two layers with different winding angles.
Method for producing tubular body made of fiber-reinforced plastic having a layer
Then , wrap the unidirectional prepreg around the core metal in both forward and reverse directions.
The starting position of each prepreg
The winding is performed with a shift of half a turn, and the number of windings of the unidirectional prepreg in the bias layer is (n + 0.1) to
A method for producing a reinforced fiber plastic tubular body, wherein n is within a range of (n + 0.4) (where n is a positive integer). 13. Each of two unidirectional prepregs
Reversed when the winding angle is within the range of 20 to 75 ° with respect to the core shaft
Wind each prepreg in both directions.
Set the beginning and the number of turns to the above-mentioned positional relationship and the number of turns.
After stacking, it winds around the core metal.
12. The method for producing a reinforced fiber plastic tubular body according to 12 .