JPH0133687B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that these reinforced fibers, which are reinforced with fibers having a high degree of stiffness and impregnated with a hardenable plastic material, are applied to a mandrel at a predetermined wrapping angle. Next, we will discuss a method for manufacturing a plastic tube made by curing the entire structure. The present invention also relates to a plastic tube made by this manufacturing method and a power transmission shaft equipped with such a plastic tube.

Fiber-reinforced plastic tubing often requires high fiber contents to obtain high values of strength and stiffness. In glass fiber reinforced plastics technology, the usual method is to carry out a final circumferential wrapping (wrapping angle of about 90°) of the glass fibers under a predetermined tension onto the finished fiber structure.
This peripheral wrapping compresses the fibrous structure underneath and extrudes excess laminated resin. However, this method is not effective in making plastic tubes reinforced with highly stiff fibers, especially carbon fibers. This is because these fibers have extremely high anisotropy. This type of winding around the carbon fiber can be performed, for example, in the longitudinal direction (with a winding angle of
(approximately 0°) or 45° winding, the anisotropy of the fibers will result in a lower temperature during the manufacturing of the tubing or its subsequent operations, during curing of the laminated resin, or during temperature fluctuations. A high degree of interlaminar stress occurs. These stresses have a very significant effect on the strength properties of the tubing.

It is therefore an object of the present invention to provide a process for producing fiber-reinforced plastic tubes which results in high fiber contents even in the case of reinforcing fibers with a high degree of stiffness or significant anisotropy.

Another object of the invention is to provide a new carbon fiber reinforced plastic tube, especially for use as a transmission or drive shaft.

The method for manufacturing fiber-reinforced plastic tubes of the present invention involves impregnating reinforcing fibers into a thermosetting resin matrix system,
This is wound around the mandrel according to the filament winding method, crossing the tube axis at a predetermined winding angle of up to ±30°, and after winding, the resin matrix system is cured by heat. In the production of fibre-reinforced plastic twisted tubes, especially power transmission shafts, in which the reinforcing fiber-resin matrix compound has considerable anisotropy, the reinforcing fibers are cured prior to curing the resin matrix system. The reinforcing fibers have a modulus of elasticity in the longitudinal direction that is lower than the modulus of elasticity in the circumferential direction of the tube of the resin matrix compound, and the thermal expansion coefficient of the reinforcing fibers in the longitudinal direction is higher than the coefficient of thermal expansion in the circumferential direction of the tube of the reinforcing fiber-resin matrix compound. Wrapping a peripheral pressure wrapping material of lightweight fiber material having a coefficient, at this time, the peripheral pressure wrapping material is
characterized by applying tension to the fibers such that they are oriented at a wrap angle in the range of 80° to 90° and the reinforcing fibers in the underlying fibrous structure are compressed and excess resin is forced out of the structure. That is.

In this manufacturing method, the reinforcing fiber content in the formed tubular body is 50 to 70% by volume.
It is preferable to apply the tension to a range of . Further, it is preferable that the wrapping material has an elastic modulus of about 3000 N/mm ² .

Further, the power transmission shaft of the present invention includes a tube made of carbon fiber reinforced plastic material, an attachment fixed to two ends of the tube, and a shaft having at least substantially the same difference as the tube. wall reinforcements consisting of a carbon fiber reinforced plastic material having a reinforcing fiber structure similar to that of the tube, tapering substantially gently towards the middle of said tube; radial bolts located in the area of the pipe and securing the fitting to the tube.

Furthermore, the present invention provides that the fiber-reinforced plastic tube is made of carbon fibers oriented at a predetermined wrapping angle with respect to the tube axis, and that the fiber-reinforced plastic tube is made of a material that is relatively elastic and has a high coefficient of thermal expansion compared to the reinforced carbon fibers. The present invention relates to a power transmission shaft further comprising a peripheral wrapping body wound around the carbon fiber at an angle in the range of ±80° to ±90° with respect to the tube axis.

According to the present invention, prior to the curing operation, the reinforcing fibers are wrapped around the reinforcing fibers with a material that is relatively elastic and has a high coefficient of thermal expansion compared to the fibers (wrapping angle of approximately ±80° to ±90°). Do it against. The wrapping material, which may be fibers, strips or cloth, for example of polyester or polyamide, is preferably applied under tension so that the fiber content of the tube wall is about 50 to 70% by volume. The elastic modulus of this wrapping material is, for example, approximately 3000 N/mm ² .

The reinforcing fibers may be carbon, with a maximum ±
It is preferable to determine the direction with a wrapping angle of 30°, preferably ±10° to ±20°. The fiber content is preferably between 50 and 70% by volume.

A torque fitting may be secured to the tube or to each end thereof to form a propulsion shaft.

In conventional power transmission shafts made of carbon fiber reinforced plastic material, such as those described in U.S. Pat. No. 4,041,599 or U.S. Pat. Joined or integrated (wrapped) with a long tubular section at each tube end. In both cases, torque transmission takes place via a joined joint, which has proven to be unsuitable, especially at high torques. Moreover, it is difficult in practice to wrap the fitting around the tube at the extremely small wrap angle (approximately .+-.10 DEG to .+-.20 DEG relative to the tube axis) required in accordance with the above precautions. All of these problems, together with the high cost of fibers, have made propulsion shafts made of fiber-reinforced plastics not traditionally advantageous.

It is therefore another object of the invention to provide a transmission shaft with improved torque introduction.

Embodiments of the plastic tube power transmission shaft and the manufacturing method thereof according to the present invention will be described in detail below with reference to the accompanying drawings.

The power transmission shaft illustrated in FIGS. 1 and 2 is reinforced with carbon fibers and is provided at each end (as shown in FIG. It consists of a reinforced plastic tube 1 (only one end is shown). A metal fitting 4 is pushed into the inner reinforcing sleeve 2. Torque is transmitted from the metal fitting 4 to the transmission shaft by means of radial bolts 5. Each bolt 5 is secured by a sleeve 6 joined to the outer reinforcing sleeve 3.

The fiber-reinforced plastic tube according to the present invention is disclosed in, for example, U.S. Pat.
It is made by the winding method described in the specifications of No. 3202560, No. 3216876, No. 3700519, and No. 4089190. As shown in FIGS. 5, 6, and 7, the reinforced carbon fiber F impregnated with curable plastic is wound around the mandrel D from two reels at a predetermined winding angle α. The fibers from one reel intersect with the fibers from the other reel so as to form a wrapping pattern as shown in FIGS. 3 and 7. The fiber F from one reel is wound around the mandrel D at an angle α, and the fiber F from the other reel is wound around the mandrel D at an angle α.
When wound around mandrel D at an angle -α, the fibers of one set intersect the fibers of the other set at an angle of 2α. The whole is then cured by heat.

The reinforced carbon fiber used was purchased from Park Avenue 270, 10017, New York City, New York, USA.
Carbon or pitch fibers sold as Thornel Type P by Union Carbide Corporation are preferred.

The inclination or wrap angle of the fibers relative to the tube axis varies according to the intended application. The winding angle α (FIG. 3) with respect to the tube axis A is about ±25° to a maximum of ±30°, but preferably a maximum of ±20° or less.
A wrap angle of less than 10° increases the elastic modulus of the tube in the longitudinal direction, but also reduces the torsional stiffness to an unacceptably low value for use as a propulsion shaft. Wrapping angles of ±11° to ±17° have proven advantageous in practice, particularly angles in the range of ±12° to ±14°. These wrap angles provide a sufficiently high torsional stiffness and a sufficiently high longitudinal bending stiffness. It is clear that it is also possible to provide a plurality of layers of reinforcing fibers each oriented with different winding angles within the given limits.

The fiber content of the plastic tube is about 50 to 70% by volume, preferably about 60 to 70% by volume. To obtain this relatively high fiber content, according to the invention, the outside of the tube is provided with a peripheral wrapping 7 (FIG. 3) of a lightweight material with a low modulus of elasticity. This lightweight material is relatively elastic compared to carbon fiber and also has a high coefficient of thermal expansion. This operation is carried out during manufacture, ie while the laminated resin is still flowable. For example, polyester (e.g. Diolene (RTM) elastic modulus approx. 3000 N/mm ² ) or polyamide (+B nylon (RTM) tearstrip (Interglass quality 7849)) can be or cloth). The coefficient of thermal expansion of this seed material must be higher in the peripheral direction than the corresponding coefficient of the reinforcing fiber-resin blend, for example about 25-30.10 ^-6 /oK and above. Peripheral wrapping has the highest tension (traction force approx.
200 to 500N). However, the traction force must of course not reach a value that would damage the material. This peripheral wrapping pushes out excess laminated resin from the fiber body, but due to its high coefficient of thermal expansion and elasticity, almost no interlaminar stress occurs during cooling after curing and during cooling of the tube.

a curable epoxy resin of low viscosity, such as the resin sold under the trade name Araldit CY209 by Ciba Geigy Aktiengesellschaft, Basel, Switzerland;
A combination with the hardener HT972 or other resin and hardener combinations having the required heat resistance and mechanical strength is used as the plastic material for the production of the tubes of the invention.

The tube 1, which is highly anisotropic and also has reinforcing fibers oriented at small angles to the tube axis, exhibits very different strengths, modulus of elasticity values and coefficients of thermal expansion, especially in the longitudinal and circumferential directions. Therefore, it has obvious significant anisotropy.

Due to the significant anisotropy of the multilayer tube structure, the reinforcing sleeves 2, 3, which sandwich the ends of the tube 1 and are subjected to high transmission torques, are made of the same or similar material as the tube 1; It is extremely important that the anisotropy is the same, or at least substantially the same. Otherwise, during temperature fluctuations, significant stresses will occur between each reinforcing sleeve 2, 3 and the tube end, leading to breakdown in extreme cases.

It is also important that the reinforced area of the tube 1 does not end abruptly, but that the thickness of the tube wall at each tube end tapers gradually down to the wall thickness of the tube 1. For this purpose, the reinforcing sleeves 2, 3 are machined so that they have a conical taper toward the center of the tube. Such a smooth continuous transition from the reinforced tube end to the unreinforced wall area of the tube 1 makes it possible to avoid stress peaks.

In FIGS. 1, 2 and 4, the wall reinforcement at each tube end is formed by a previously formed reinforcing sleeve glued to the outside or inside of the tube 1. In FIGS.
However, these reinforcements may be made in a number of other ways. However, in this case, the winding method requires the use of an extremely small winding angle, so it is not very easy.

For example, as shown in FIG. 5, reinforcing sleeves 12 of a suitable shape, which have been previously formed and are placed on a mandrel D used for making a tube at intervals corresponding to the desired length of the tube, are By covering it with carbon fiber F, it can be integrated into a tube structure.

As shown in FIG.
Use 2. The winding 22 consists of a unidirectional fiber cloth G. The fibers of the fabric G are aligned to occupy the same position within the winding 22 as the fibers of the tube so as to provide the same anisotropy.

Integrating the wall reinforcement directly into the tubular fiber structure (fifth step)
Figures 6 and 6) Alternatively, wrapping 22 of unidirectional cloth G
may be subsequently applied to the finished tube 1 as shown in FIG.

For continuous tube production, as is conventional in the case of glass fiber reinforced plastic tubes, the most advantageous method is to wrap the tube over a preformed sleeve as shown in FIG. It is thought that.

In the case of tubes made according to FIGS. 5, 6 and 7, each tube end is simply thickened outwardly. However, this is not a problem if the wall thickness thus obtained is sufficient to absorb the stresses caused by the torques applied during use.

The cardan type transmission shaft made of plastic material with a winding angle of ±12° to the axis and a pitch fiber content of 70% of the total material volume has a critical speed of more than 8100 Npm and a required maximum shaft torsion angle of 12°. It had such twisting stiffness that it could not be exceeded by the torque (1500Nm).

Although the present invention has been described in detail with reference to its embodiments, it is obvious that the present invention can be modified in various ways without departing from its spirit.

[Brief explanation of drawings]

FIG. 1 is a axial cross-sectional view of one end of an embodiment of a power transmission shaft manufactured by the manufacturing method of the present invention, and FIG.
3 is a reduced perspective view showing the winding structure of the tube constituting the shaft in FIG. 1; FIG. 4 is an axial sectional view of the wall reinforcement of the shaft in FIG. 1; FIG. 5 is a sectional view taken along the line; , FIG. 6, and FIG. 7 are manufacturing process diagrams of different wall reinforcing materials produced by the present manufacturing method. 1...Pipe, 2, 3...Sleeve (wall reinforcement material),
4... Stump, 5... Bolt, F... Fiber, D...
Mandrel.

Claims (1)

[Scope of Claims] 1 (a) a tube made of carbon fiber reinforced plastic material; (b) fittings fixed to two ends of the tube; and (c) fittings provided at each end of the tube, a wall reinforcement consisting of a carbon fiber reinforced plastic material having a reinforcing fiber structure similar to that of the tube, having at least approximately the same anisotropy as said tube, tapering substantially gently towards the middle of said tube; (d) radial bolts located in the area of these wall reinforcements and securing said fitting to said tube. 2. The power transmission shaft according to claim 1, comprising a sleeve fixed to each end of the tube and fixing a radial bolt. 3. The power transmission shaft according to claim 2, wherein each end of the tube is reinforced only on the outside of the tube. 4. The power transmission shaft according to claim 1, wherein each end of the tube is reinforced both on the outside of the tube and on the inside of the tube. 5. The power transmission shaft according to claim 1, in which the wall reinforcing material is integrated with the pipe. 6. A power transmission shaft according to claim 4, wherein the wall reinforcement is formed by separately made tubular sections that are wound around the tubular structure during its manufacture. 7. Transmission shaft according to claim 1, wherein the wall reinforcement is formed by local additional wrappings of unidirectional fiber fabric applied during manufacture of the tube. 8. The power transmission shaft according to claim 7, wherein the additional winding body is arranged above the tube fiber. 9. The power transmission shaft according to claim 7, wherein at least some of the tube fibers are arranged above the additional winding. 10. A power transmission shaft according to claim 1, wherein the wall reinforcement is formed by separately made tubular sections joined to the tube. 11 (a) A tube formed of carbon fibers oriented at a predetermined wrapping angle with respect to the tube axis, and (b) a tube that is relatively elastic and has a high coefficient of thermal expansion compared to the reinforcing carbon fibers. (c) a peripheral wrap made of a material wrapped around the carbon fiber at an angle in the range of ±80° to ±90° with respect to the tube axis; a carbon fiber-reinforced plastic material having a reinforcing fiber structure similar to that of said tube and having at least approximately the same anisotropy as said tube, with a substantially gradual taper toward the middle of said tube; wall reinforcement material with
A power transmission shaft comprising a fitting at each end of the tube; and (e) a radial bolt located in the area of each wall reinforcement and securing the fitting to the tube. 12. The power transmission shaft according to claim 11, wherein the reinforcing fiber content is in the range of 50 to 70% by volume. 13. The power transmission shaft according to claim 11, wherein substantially all of the reinforcing fibers are oriented at an angle of at most ±30° with respect to the tube axis. 14 Place the reinforcing fibers at an angle of ±10° or ± to the tube axis.
14. A power transmission shaft as claimed in claim 13, oriented at an angle of 20 degrees. 15 Impregnating the reinforcing fiber into a thermosetting resin matrix system, wrapping it around the mandrel according to the filament winding method at a predetermined winding angle of up to ±30° with respect to the tube axis, and then winding it. Reinforcement fibers made by curing the resin matrix system with heat - resin matrix
In the production of fibre-reinforced plastic twisted pipes, especially power transmission shafts, in which the compound has considerable anisotropy, a cured reinforcing fiber-resin matrix is applied on top of the reinforcing fibers prior to curing the resin matrix system. The reinforcing fiber-resin matrix is made of a lightweight fiber material having a fiber longitudinal elastic modulus lower than the tube circumferential elastic modulus of the compound and a fiber longitudinal thermal expansion coefficient higher than the tube circumferential thermal expansion coefficient of the compound. The peripheral pressure wrapping material is wound such that the peripheral pressure wrapping material is oriented at a wrapping angle in the range of 80° to 90° with respect to the tube axis, and the reinforcing fibers in the lower fibrous structure are A method for making fiber reinforced plastic tubing characterized by applying tension to the fibers so that the compressed excess resin is forced out of the structure. 16. Fiber reinforcement according to claim 15, wherein the peripheral pressure wrapping material is applied under tension such that the reinforcing fiber content in the formed tubular body is in the range of 50 to 70% by volume. How to make plastic pipes. 17. The method for manufacturing a fiber-reinforced plastic tube according to claim 16, wherein organic fiber is used as the peripheral pressure wrapping material. 18. The method for producing a fiber-reinforced plastic tube according to claim 17, wherein polyester fiber is used as the organic fiber. 19. The method for producing a fiber-reinforced plastic tube according to claim 17, wherein polyamide fibers are used as the organic fibers. 20. The method for producing a fiber-reinforced plastic tube according to claim 15, wherein carbon fiber is used as the reinforcing fiber. 21. A method for producing a fiber-reinforced plastic tube according to claim 15, which allows the peripheral pressure wrapping to be applied under maximum tension without damage to this material. 22. The method for producing a fiber-reinforced plastic pipe according to claim 15, wherein the thermal expansion coefficient of the peripheral pressure wrapping material is larger than the corresponding coefficient of the reinforcing fiber-resin compound in the circumferential direction. 23 Thermal expansion coefficient is approximately 25 to 30・10 ^-6 /ok
23. A method for manufacturing a fiber-reinforced plastic tube according to claim 22, which increases the height of the tube. 24. The method for manufacturing a fiber-reinforced plastic tube according to claim 15, wherein the elastic modulus of the peripheral pressure wrapping material is about 3000/mm ² .