JPH1016068A - Manufacture of tube body constituted of fiber-reinforced thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain an improvement in the productivity of a preform and to provide a tube body being more inexpensive and having a higher quality. SOLUTION: A prepreg sheet 2 which is formed of a matrix 5 constituted of reinforcing fibers 4 disposed in a plurality of directions and of thermoplastic resin, which is made longitudinal in a direction wherein it has the maximum bending rigidity and of which the rigidity in the lateral direction is made 70% of that in the longitudinal direction is wound in two or more turns to be tubular so that the longitudinal direction thereof is the axial direction of a tube body 1. A preform 3 thus prepared is inserted between a core and an outer die and body is molded by heating and pressing by the force of expansion of the core. Thereby the tube body constituted of the fiber-reinforced thermoplastic resin is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a tubular body made of a fiber-reinforced thermoplastic resin using a prepreg sheet containing a thermoplastic resin as a matrix. The present invention relates to a method for manufacturing a cylindrical body made of a fiber-reinforced thermoplastic resin, which can be manufactured efficiently by making the size smaller than the longitudinal direction.

[0002]

2. Description of the Related Art In general, a composite material using a so-called engineering thermoplastic resin such as polyetheretherketone as a matrix is more tough and heat-resistant than a composite material using a thermosetting resin such as an epoxy resin as a matrix. ,
Excellent environmental resistance. For this reason, an attempt has been made to form a laminated molded product, for example, a tubular body with a prepreg sheet using these thermoplastic resins as a matrix, and to use this tubular body as a structural member such as a torque tube or a cushioning material such as a crash element.

[0003] As a method of manufacturing the tubular body, a prepreg sheet in which a matrix made of a thermoplastic resin is impregnated into a reinforcing fiber layer in which a plurality of continuous fibers are aligned in one direction is spirally wound and laminated. Core made of a heat-expandable resin such as polytetrafluoroethylene, or a core formed by enclosing a fluid in a flexible cylindrical bag. Is inserted, and the outside is covered with an outer mold.Then, the preform and the core are heated to soften or melt the thermoplastic resin, and the preform is press-molded by the expansion force of the core to form a cylindrical body. There are known methods (for example, JP-A-6-71654 and JP-A-5-293908).

[0004]

However, the above-mentioned method involves the use of polyetheretherketone (PEEK).
This is an effective technique as compared with a manufacturing method that has been conventionally performed, such as filament winding, as a method of manufacturing a fiber-reinforced thermoplastic resin cylindrical body using a thermoplastic resin having a high plasticization temperature as a matrix.

[0005] However, the prepreg sheet using the above-mentioned thermoplastic resin as a matrix is a hard sheet having almost no tackiness at room temperature, but has the following problems. That is, the process of spirally winding a prepreg sheet in which a plurality of continuous fibers are aligned and reinforcing fibers arranged in one direction, and laminating and forming a cylindrical preform is time-consuming and considerably complicated.

In order to achieve the required strength and rigidity, the prepregs in at least two different directions must be wound, for example, by overlapping them, but the directional prepreg sheet must be aligned with the axis of the cylindrical body. When rolled, the material tends to be deformed into a bamboo shoot due to warping of the material. Also, it is difficult to bring the two layers of the prepreg into close contact with each other because the direction of the warpage is different, so that it is difficult to exceed a certain limit, and the thickness of the preform is often thicker than calculated.

[0007] For example, a prepreg sheet made of carbon fiber and polyetheretherketone and having a thickness of 0.125 mm is placed in a direction opposite to the axis by ± 30 degrees.
When 0 layers are wound, the thickness is calculated to be 2.5 mm, but a gap may be formed and the thickness may be even 1.5 times as large as 3.75 mm. In this case, the expansion of the expandable core is Must be bigger, and if it is not enough, it will be underpressed,
In some cases, sufficient adhesion between layers may not be obtained.

In addition, a prepreg sheet in which reinforcing fibers are arranged in one direction is apt to be torn along the fiber direction at a cut end, so that care must be taken in molding the preform. Also, in the conventional internal pressure molding method, a molding temperature such as polyetheretherketone (PEEK) is high and can be applied to an expensive material, but a material having a relatively low molding temperature (300 ° C. or lower) such as a nylon resin. However, the thermal expansion of the mandrel was insufficient, and the gap could not be completely eliminated.

The present invention has been devised in view of such conventional problems, and is intended to improve the productivity of preforms and stabilize the quality, and to use a less expensive and higher quality fiber reinforced thermoplastic resin. It is an object of the present invention to provide a method for manufacturing a cylindrical body.

[0010]

In order to achieve the above object, the present invention firstly comprises a matrix composed of a thermoplastic resin and a reinforcing fiber in which fibers are arranged in a plurality of directions. Direction, and the horizontal direction, that is,
A prepreg sheet is prepared in which the rigidity in the direction substantially 90 degrees to the longitudinal direction is set to 70% or less of the rigidity in the longitudinal direction.

Next, the prepreg sheet is rolled into a tubular shape two or more times so that the longitudinal direction is the axial direction of the tubular body, thereby producing a preform. Then, insert the core into the preform, cover the outer mold with the outside, heat the preform and the core with a heating means such as an oven, plasticize the matrix of the preform, and expand the heated core. The preform is pressed with a force and an outer mold, and the layers of the wound prepreg sheet are fused and integrated to form a cylindrical body. The matrix of the cylindrical body is cooled and cooled by cooling means such as water, and the hardened cylindrical body is released from the core and the outer mold to produce a cylindrical body made of a fiber-reinforced thermoplastic resin.

The reinforcing fibers of the prepreg sheet are arranged such that fiber bundles are arranged in the longitudinal direction of the prepreg sheet and in the transverse direction which is substantially perpendicular to the longitudinal direction, and the bending stiffness of the prepreg sheet in the transverse direction is increased in the longitudinal direction. Rigid 7
The use of reinforcing fibers having a concentration of 0% or less is one of the preferable choices because molding becomes easier. By setting the content to 70% or less, the prepreg sheet can be easily wound and can be tightly wound. It is also one of the preferable choices to use, as the reinforcing fiber, a reinforcing fiber obtained by combining a longitudinal fiber and a nondirectional nonwoven fabric.

It is also a preferable choice to use a reinforcing fiber obtained by combining a longitudinal fiber and a knit as the reinforcing fiber. As the core, it is preferable to use a material made of a thermally expandable resin such as polytetrafluoroethylene, and to expand the core by heating to press the preform.

As the core, a flexible tubular bag in which a fluid such as air or water is sealed is used, and the preform is pressed by increasing the pressure by pressurizing and heating the fluid. Is also preferable. The cylinder manufactured by the above method is used as a so-called crash element that is used for aircraft, automobiles, etc., receives an impact in the axial direction of the cylinder, breaks the cylinder by the impact force, and absorbs impact energy. The above manufacturing method is also a preferable method for manufacturing a crush element.

Further, the cylinder manufactured by the above method can be used as a so-called torque tube used for transmitting torque in various devices, and the above manufacturing method is a preferable method as a method of manufacturing a torque tube. is there.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a manufacturing process of the present invention, wherein a bag 1 is a prepreg sheet 2 and a preform 3.
It is manufactured through the steps of In FIG. 1A, a prepreg sheet 2 is composed of a matrix 5 made of reinforcing fibers 4 and a thermoplastic resin, and the reinforcing fibers 4 align a longitudinal fiber bundle 6 in the longitudinal direction of the prepreg sheet 2, and That is, the horizontal fiber bundles 7 are aligned in a direction perpendicular to the vertical fiber bundles, and are formed in a sheet shape using the matrix 5 as a medium. The reinforcing fibers 4 constitute the vertical fiber bundle 6 and the horizontal fiber bundle 7 such that the rigidity in the horizontal direction of the prepreg sheet 2 is 70% or less of the rigidity in the vertical direction.

For example, when fiber bundles having the same rigidity are used for the vertical fiber bundle 6 and the horizontal fiber bundle 7, the horizontal fiber bundle 7
70% of the drawing density of the longitudinal fiber bundle 6
When the vertical fiber bundle 6 and the horizontal fiber bundle 7 have the same drawing density, the rigidity of the horizontal fiber bundle is set to 70% or less, and the rigidity of the prepreg sheet 1 in the horizontal direction is reduced. The rigidity in the direction is 70% or less. In this case, the reinforcing fibers may be woven with longitudinal fibers and weft fibers.

Further, as shown in FIG. 1 (b), reinforcing fibers 6 'are arranged in one direction in a single prepreg sheet 1 in a biased manner so as to have a constant angle θ with respect to the longitudinal direction. You may. By changing the intersection angle 2θ, the above-described rigidity ratio in the vertical direction and the horizontal direction can be appropriately adjusted. Next, in FIGS. 1 (c) and 1 (d),
The preform 3 is formed by a prepreg sheet 2 in which the longitudinal fiber bundle 6 is wound two or more times so as to form the axial direction of the cylindrical body 1.

As shown in FIG. 2, the preform 3 is inserted between a cylindrical outer die 8 and a cylindrical core 9. Outer die 8
Is made of a metal or the like, and the core 9 is made of a resin such as polytetrafluoroethylene having a high thermal expansion property. The core 9 and the preform 3 are heated by a heating means such as an oven, and the matrix 5 is plasticized. In this state, the preform 3 is pressed by the expansion force of the core and the outer mold to form a cylinder. Then, they are cooled by means such as placing them in water, and the preform hardened by cooling, that is, the cylindrical body is released from the core and the outer mold to obtain a completed cylindrical body.

The matrix is a thermoplastic resin,
Polycarbonate, polyamide, polypropylene, polyester, polymer alloy and the like are suitable. Further, as the reinforcing fiber, a fiber having high heat resistance and high strength such as carbon fiber, glass fiber, aramid fiber, silicon carbide fiber, boron fiber, and alumina fiber is preferable. The resin impregnation state and smoothness of the prepreg are as complete as possible.
Those having high smoothness are preferred.

The core is desirably made of a material having high heat resistance and thermal expansion properties, such as polytetrafluoroethylene resin. The core 9 may be an inflatable core in which a fluid is sealed in a flexible tubular bag. In this case, insert a tubular bag that does not or does not sufficiently seal the fluid into the preform, assembles it into the outer mold, and then seals and pressurizes fluid such as air, water, etc. The reform can be pressed and further pressed by heating. In this way, the core is easily inserted into the preform even if the inner diameter of the preform is made smaller.

FIG. 3 shows another embodiment of the prepreg sheet 2 in which the reinforcing fibers 4 are formed by overlapping a longitudinal fiber bundle 6 aligned in the longitudinal direction and a non-directional nonwoven fabric 10. Also in this case, the rigidity in the horizontal direction is adjusted to 70% or less of the rigidity in the vertical direction. FIG. 4 shows still another embodiment of the prepreg sheet 2, in which the reinforcing fibers 4 are formed by overlapping the vertical fiber bundle 6 and the knit 11 that are aligned in the vertical direction. In this case, the rigidity in the horizontal direction is 70% of the rigidity in the vertical direction.
It has been adjusted below.

According to the present invention, the stiffness in the horizontal direction of the prepreg sheet is 70% or less of the stiffness in the vertical direction and is small. Therefore, when the prepreg sheet is wound into a preform, the prepreg sheet is easily wound. In particular, the thermoplastic resin described above often has little tackiness, so that it is difficult for the interlayers to adhere to each other. For this reason, when the rigidity in the lateral direction is large, the gap between the layers becomes large, and the preform becomes bulky in the radial direction, and its outer diameter is increased. Becomes larger.

In such a case, in order to insert the preform between the core and the outer mold, the outer diameter of the core must be reduced by using a core having a large thermal expansion. The core material is scarce. That is, since the present invention uses a prepreg sheet having a small lateral rigidity,
Even if a resin having low tackiness is used for the matrix, the prepreg sheet is easy to wind, there is almost no gap between the layers, and a preform having a small thickness and no bulk can be produced.

Also, since the rigidity in the lateral direction is small, the roll does not collapse and the rebound of the sheet edge is small, so that the shape of the preform can be maintained by simply welding the edge, and the core and the outer mold can be maintained. Is easy to mount. In addition, since the preform is made ideally in this way, the finished bag does not undergo uneven thickness or delamination. If the stiffness in the horizontal direction exceeds 70% of the stiffness in the vertical direction, the gap between the layers of the preform becomes large, and it becomes difficult to manufacture the preform.

[0026] Further, when the preform is formed by winding the prepreg by one layer, the preform can be produced by the production method of the present invention.
In this case, since the preform does not become bulky, the effect of the present invention is small. As described above, according to the present invention, a high-quality bag can be manufactured using a high-performance material, so that a crash element, a torque tube, and the like, which require high performance and reliability, can be easily manufactured. it can.

[0027]

EXAMPLES Bags having the same outer diameter and length were manufactured by the manufacturing method of the present invention (Examples 1 and 2) and other manufacturing methods (Comparative Examples 1 and 2). The superiority was evaluated. (Example 1) A prepreg sheet was prepared in which two directional glass plain woven fabrics in which fibers were arranged so that the ratio of the longitudinal direction to the lateral direction was 7: 3 were used as reinforcing fibers, and nylon 6 was used as a matrix. . In this case, the measured values of the stiffness of the prepreg sheet were that the stiffness in the transverse direction was 54% of the stiffness in the longitudinal direction, and the thickness of the prepreg sheet was 0.33 mm. The fiber volume content was 50%.

Next, the prepreg sheet is wound so that the longitudinal direction of the prepreg sheet is the axial direction of the cylinder, the inner diameter is 46.5 mm, and the prepreg sheet is wound so that the layers are in close contact with each other. Made. Next, a core made of polytetrafluoroethylene, having an outer diameter of 46 mm and an inner diameter of 19 mm was inserted into the preform, and a release-treated polyimide film was wound around the preform one round, and the inner diameter was 55.0 mm. It was inserted into the outer mold.

Then, it was placed in an oven at 250 ° C., left standing for 60 minutes while keeping it horizontal, taken out of the oven, cooled in water, and then released from the cured cylinder. (Example 2) A prepreg sheet having a polypropylene matrix as a reinforcing fiber was prepared by aligning fiber bundles made of glass fibers in the longitudinal direction, combining the nonwoven fabric made of glass fibers with a non-woven fabric. In this case, the measured value of the stiffness of the prepreg sheet is that the stiffness in the transverse direction is 25 times the stiffness in the longitudinal direction.
%, And the thickness of the prepreg sheet was 0.33 mm. The fiber volume content was 45%.

Next, a preform was manufactured in the same manner as in Example 1. In this case, the preform is shown in Table 1 below.
It became the size shown in. Next, a pre-ohm was inserted into the same core and outer mold as the cylinder 1 by the same method, heated and cooled under the same conditions, and the cured cylinder was released and taken out. (Comparative Example 1) A prepreg sheet using nylon 6 as a matrix was prepared by reinforcing a fiber bundle made of glass fibers in only one direction to form reinforcing fibers. In this case, the thickness of the prepreg sheet was 0.15 mm.

Next, the two-leaf prepreg sheets were wound in directions opposite to each other so that the fiber bundle was ± 30 degrees with respect to the axial direction of the cylinder. However, since the two-leaf prepreg sheet collapsed and it was difficult to form a tightly wound preform, it was necessary to fix several places by welding from the inside of the preform.

The bulk of the preform is large, and the thickness of the preform is 280% of the thickness of the completed cylinder.
Therefore, a heat-expandable core was not used, and a heat-molding was performed under the same conditions as in Example 1 using a fluid-filled flexible bag core. The produced bag body was slightly uneven in thickness, and the ends were rough due to the collapse of the preform. The ends of the bag protruded from the mold during the heat molding, making it difficult to remove the core.

(Comparative Example 2) The fibers were arranged in the longitudinal direction and the lateral direction:
The prepreg sheet was prepared in the same manner as in Example 1 except that two glass plain woven fabrics having the same rigidity in both directions were combined to form reinforcing fibers, and a nylon 6 matrix was prepared. In this case, the rigidity in the lateral direction is the same as in the first embodiment.
It was 1.7 times.

It was difficult to wind the prepreg sheet so that the preform could be inserted into an outer mold having an inner diameter of 55 mm, because the rigidity of the prepreg sheet in the lateral direction was high and the gap between the layers was large. Therefore, the expected 10
The circumference could not be wound, and it was wound 9 times. In this case, the gap between the layers was 0.126 mm on average. The appearance of the completed cylinder was good, but there was uneven thickness in the circumferential direction and delamination occurred in a part of the thick part. Table 1 shows the main points of the above examples and comparative examples.

[0035]

[Table 1]

[0036]

Since the present invention is configured as described above, it has the following effects.
Since the stiffness in the transverse direction is 70% or less of the stiffness in the longitudinal direction and the prepreg sheet having a small stiffness in the transverse direction is used, the prepreg sheet is easy to wind even if a resin having low tackiness is used for the matrix, It is possible to make a thin, non-bulky preform with almost no gap.

Further, since the preform does not collapse and the rebound of the edge of the sheet is small, the shape of the preform can be easily maintained, the core and the outer mold can be easily mounted, and the expansion resin can be used. The child is easy to use. In addition, since the preform is ideally manufactured, a homogeneous and high-quality cylindrical body free from uneven thickness and delamination can be manufactured even with an inexpensive material having a relatively low molding temperature. Therefore, it is possible to easily manufacture a crash element or a torque tube that requires high performance and reliability.

That is, according to the present invention, the high productivity and high quality fiber-reinforced thermoplastic resin described above is used.
A cylinder such as a crash element or a torque tube can be manufactured.

[Brief description of the drawings]

1A to 1D are a partially cutaway plan view and a perspective view showing a manufacturing process of the present invention.

FIG. 2 is a cross-sectional view showing a molding step of the present invention.

FIG. 3 is a partially cutaway plan view showing an example of the prepreg sheet of the present invention.

FIG. 4 is a partially cutaway plan view showing an example of the prepreg sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical body 6 Vertical fiber bundle 2 Prepreg sheet 7 Horizontal fiber bundle 3 Preform 8 Outer type 4 Reinforcement fiber 9 Core 5 Matrix

Claims (6)

[Claims] 1. A matrix made of a thermoplastic resin and reinforcing fibers in which fibers are arranged in a plurality of directions, wherein the direction having the maximum bending rigidity is defined as the longitudinal direction, and the lateral rigidity is 70% or less of the longitudinal rigidity. The prepreg sheet set to
A preform is formed by winding two or more turns in a cylindrical shape so that the longitudinal direction is the axial direction of the cylindrical body, a core is inserted into the preform, and an outer mold is put on the outside thereof, and the preform and the core are formed. Is heated by a heating means to plasticize the matrix of the preform, and by pressing the preform with the expansion force of the core and the outer mold, the layers are fused to form a cylinder, and the cylinder is cooled by the cooling means. A method of manufacturing a cylinder made of a fiber-reinforced thermoplastic resin, wherein the matrix is cooled and cured, and the cured cylinder is released from the core and the outer mold. 2. The fiber according to claim 1, wherein the reinforcing fibers comprise a longitudinal fiber bundle and a lateral fiber bundle substantially perpendicular to the longitudinal direction.
A method for producing a tubular body comprising the fiber-reinforced thermoplastic resin described in the above item. 3. The method for producing a tubular body according to claim 1, wherein the reinforcing fibers are made of the fiber-reinforced thermoplastic resin according to claim 1, which is a combination of longitudinal fibers and non-directional nonwoven fabric. 4. The method for producing a tubular body according to claim 1, wherein the reinforcing fibers are made of the fiber-reinforced thermoplastic resin according to claim 1, wherein the longitudinal fibers and the knit are combined. 5. The preform according to claim 1, wherein the core is made of a heat-expandable resin, and the core is expanded by heating to press the preform. A method for producing a cylindrical body made of a fiber-reinforced thermoplastic resin. 6. The preform according to claim 1, wherein the core has a fluid sealed in a flexible tubular bag, and the preform is pressed by an increase in the pressure of the fluid. Item 3
A method for producing a tubular body comprising the fiber-reinforced thermoplastic resin according to claim 4.