JPH0353106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a method for manufacturing carbon fiber reinforced synthetic resin pipes.

[Prior art]

Carbon fiber reinforced synthetic resin pipe (hereinafter referred to as CFRP)
Because they have extremely high strength, Young's modulus, and bending elasticity, as well as being lightweight, they are being used as an alternative to conventional metal tubes in the drive shafts of helicopters, the masts of communications satellite antennas, etc. It is becoming widely adopted as a product.

This CFRP pipe has conventionally been manufactured by the method described in Japanese Patent Publication No. 16427/1983. The manufacturing method of this CFRP pipe involves wrapping a prepreg tape made of a large number of carbon fibers aligned in the same way and bonded with uncured thermosetting synthetic resin around the outer periphery of a mandrel made of a metal with a large coefficient of linear expansion. A coarse fiber tape that allows the flowing resin to pass through and a resin covering that absorbs the excess resin of the prepreg layer are sequentially wrapped around the outside of the prepreg layer, and the excess resin of the prepreg layer is removed by vacuum suction. After absorbing residual air (air that entered between the tapes when wrapping the prepreg tape) through the fiber tape and absorbing the excess resin with a resin absorbing material, the resin is heated to a temperature that hardens the resin of the prepreg layer. Then, the prepreg layer is pressurized from the inside by the thermal expansion of the mandrel to harden the resin, and after the temperature is lowered, the resin absorbing material impregnated with excess resin and the fiber tape are peeled off. This is a method of cutting a molded tube from a shrunken mandrel, and this manufacturing method allows for easy and efficient production of CFRP.
Tubes can be manufactured.

Recently, in addition to the conventional bleed type prepreg tape, which has a surplus of resin, non-bleed type prepreg tapes, in which the amount of resin is controlled to the minimum necessary, have also come into use. When manufacturing CERP pipes using this non-bleed type prepreg tape, there is no need to absorb excess resin from the prepreg layer, so in this case, it is necessary to absorb excess resin from the outside of the prepreg layer wrapped around the mandrel. The resin of the prepreg layer may be cured after winding an air-permeable fiber tape and absorbing the residual air in the prepreg layer by vacuum suction.

[Problem that the invention seeks to solve]

However, in the conventional manufacturing method described above, traces of the fibers from the fiber tape wrapped around the outside of the prepreg layer remain on the outer surface of the manufactured CFRP pipe, and fibers wrapped around the outside of the prepreg layer remain in the form of a network. If the tape has wrinkles, the wrinkles will leave traces on the outside surface of the pipe, making it impossible to obtain a CFRP pipe with a smooth outside surface without any irregularities. This is the same when a perforated resin film with a large number of holes is used instead of the fiber tape, and in that case as well, there are no traces of the holes in the perforated resin film on the outer surface of the manufactured CFRP pipe. Traces of the "wrinkles" of this resin film will remain. Although this unevenness on the outer surface of the tube does not affect the strength of the CFRP tube itself, it does not look good, and depending on the use of the CFRP tube, unevenness on the outer surface of the tube may become a problem. There is also.

Note that if the outer surface of the manufactured CFRP tube is polished, the outer surface of the tube can be finished to a smooth surface with no irregularities, but this will cut the carbon fibers on the outer surface of the tube, so the CFRP tube cannot be polished. The strength, etc. of

An object of the present invention is to provide a method for manufacturing a CFRP pipe that can produce a CFRP pipe with a high quality shape and a smooth outer surface without irregularities.

[Means to solve problems]

This invention involves wrapping a prepreg tape made of a large number of carbon fibers aligned in the same direction and bonded with an uncured thermosetting synthetic resin around the outer periphery of a mandrel made of a metal with a large coefficient of linear expansion. A plurality of tape-shaped metal foils having a width slightly wider than the length obtained by dividing the circumference of the prepreg layer into multiple pieces and having a coefficient of linear expansion sufficiently smaller than that of the mandrel are placed on the outside of the prepreg layer in the axial direction of the prepreg layer. The entire circumference of the prepreg layer is covered with the metal foil, and a breathable binding tape is wrapped around the outer circumference of the prepreg layer. The metal foil is tightened to the prepreg layer, and in this state, residual air or residual air and excess resin in the prepreg layer are removed by vacuum suction through the lap portions of each metal foil and the binding tape, and then the curing temperature of the resin is The method is characterized in that the resin is cured while applying pressure to the prepreg layer from the inside due to the thermal expansion of the mandrel, and then the binding tape and metal foil are peeled off, and a molded tube is cut out from the mandrel. That is.

[Effect]

That is, in this invention, a plurality of tape-shaped metal foils having a coefficient of linear expansion sufficiently smaller than that of the mandrel are placed on the outside of a prepreg layer wound around a mandrel, and the side edges of each metal foil are wrapped around each other to wrap the entire prepreg layer. The metal foil is wrapped to cover the periphery, and this metal foil is fastened to the prepreg layer with a breathable bonding tape, and residual air or residual air and excess resin in the prepreg layer is removed and the resin is cured. In this invention, the residual air in the prepreg layer or the excess resin combined with the residual air is removed through the lap part of the metal foil. There is no need to provide holes or the like for this purpose, and therefore, there is no problem of fiber traces from the fiber tape or traces from the holes in the perforated resin film remaining on the outer surface of the CFRP pipe manufactured using conventional manufacturing methods. Moreover, in this invention, since the metal foil is made of a material having a coefficient of linear expansion sufficiently smaller than that of the mandrel, even if the mandrel thermally expands during resin curing, the metal foil hardly elongates due to heat. Even if the metal foil covering the prepreg layer has wrinkles, when the prepreg layer is pressurized from the inside due to the thermal expansion of the mandrel, the metal foil tightened from the outside with the binding tape will not be affected by the pressure from the inside. The "wrinkles" are stretched by pressure, and therefore, the "wrinkle" marks of the fiber tape or perforated resin film are left on the outer surface of the CFRP pipe manufactured using the conventional manufacturing method. There's nothing left.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows the manufacturing method for CFRP pipes in the order of steps. Note that this example uses a bleed type prepreg tape that requires absorbing excess resin.

In FIG. 1, numeral 1 in the figure is a molding mandrel. This mandrel 1 is made of a metal tube, such as an aluminum tube, with a large coefficient of linear expansion.
Its outer surface is finished smooth and hardened by Toughflam treatment or the like.

To explain the manufacturing method of this CFRP pipe, first,
After applying a mold release agent such as silicone grease to the outer surface of the mandrel 1, as shown in FIG. Produce prepreg tape a bonded with curable synthetic resin
Wrap it evenly to the required thickness depending on the wall thickness of the CFRP pipe.

Figure 2 shows how to wrap this prepreg tape a.If the direction of the carbon fiber is oblique to the axial direction of the CFRP pipe to be manufactured, the length can be adjusted as shown in Figure 2a. Wrap a narrow strip of prepreg tape a with carbon fibers running in the direction around the mandrel 1 in a spiral shape, or
Or, as shown in Figure 2b, the CFRP to be manufactured
A wide prepreg tape (cut diagonally from the prepreg tape material with respect to the direction of the carbon fibers) a, which is approximately the same width as the length of the tube and has carbon fibers running diagonally through it, can be wrapped around the mandrel 1 in a roll. . In addition, when the direction of the carbon fiber is parallel to the tube axis direction, as shown in FIG. As shown in FIG. As shown in Figure e, a wide prepreg tape with carbon fibers running vertically.
It is sufficient to wind it around the mandrel 1 in the form of a roll. Note that some CFRP pipes only require carbon fibers to run in one direction, while others require carbon fibers to run in two or more directions. For winding 2, choose one of the above winding methods depending on the type of CFRP pipe to be manufactured, or
Alternatively, a combination of two or more may be used.

The prepreg tape 2 is wound around the mandrel 1 by heating the mandrel 1 to a temperature at which the resin of the prepreg tape 2 flows. When the prepreg tape 2 is wound a number of times to a uniform thickness, the resin of the wrapped prepreg tape 2 becomes fluidized by the heat of the mandrel 1, and the wrapped and laminated prepreg tape a becomes one prepreg layer A.

After this, as shown in FIG. 1b, a resin absorption material 2 such as glass cloth is wrapped around the outside of the prepreg layer A, and the outside is packed airtight with a backpack film 3 such as nylon film. Perform temporary bagging. This temporary bagging is carried out in a closed tank, where the air inside the pack is vacuum-suctioned and gradually heated to a temperature at which the resin of the prepreg layer A flows.
If the pressure is increased to about atmospheric pressure, most of the residual air and excess resin in prepreg layer A will be removed by vacuum suction force and pressure from the surroundings (excess resin will be absorbed by resin absorption material 2). .

After performing this temporary bagging, the back pack film 3 and the resin absorbing material 2 are removed, and if there are any irregularities on the outer surface of the prepreg layer A, they are leveled with a roller or the like. As shown in FIG. It is coated to cover the entire circumference.
The metal foils 4, 4 can be bent freely, and for example, stainless steel foil having a coefficient of linear expansion about 1/2 that of aluminum, which is the material of the mandrel 1, is used. The metal foils 4, 4 are cut to have a length that is approximately the same as the axial length of the prepreg layer A, and a width that is slightly wider than the half circumference of the prepreg layer A. As shown in the figure, first one metal foil 4 is applied along the axial direction of the prepreg layer 4, and then another metal foil 4 is applied to the other half of the prepreg layer A on both sides. By wrapping the edges around both side edges of the metal foil 4 that was previously applied to the prepreg layer A, the entire circumference of the prepreg layer A is covered as shown in Fig. 4. . Note that the surfaces of the metal foils 4, 4 that are in contact with the prepreg layer A are subjected to a peeling treatment by applying a peeling agent such as silicone grease.

After this, as shown in FIG. 1d, first, an air-permeable binding tape 5 through which a fluid resin such as a Teflon lid (commercially available) can pass is placed around the outer periphery of the metal foils 4, 4 covered with the prepreg layer A. The metal foils 4, 4 are tightly wound around the outer periphery of the prepreg layer A so as not to loosen. FIG. 5 shows a method of winding this binding tape 5. This binding tape 5 is wound in a spiral shape so that its side edges do not overlap.

Next, as shown in FIG. 1e, a resin absorption material 6 such as glass cloth is wrapped around the outside of the bonding tape 5 to a required thickness, and the outside is further airtightly covered with a backpack film 7 such as a nylon film. Then, carry out main bagging to completely remove the excess resin from the prepreg layer A. This book bagging is also done in a sealed tank.
By vacuum suctioning the air inside the pack and gradually heating it to a temperature at which the resin in prepreg layer A flows, and further pressurizing the inside of the tank to about 6 atmospheres, all of the residual air and excess resin in prepreg layer A can be removed. is removed through the lapped portions of the metal foils 4, 4 and the binding tape 5 by vacuum suction and pressure from the surroundings (excess resin is absorbed by a resin absorbent 6). The lap width of the metal foils 4, 4 is approximately 15 mm.
~20mm, and with this wrap width, the residual air and excess resin in the prepreg layer A will be
It is removed through the lap of the metal foils 4, 4 without resistance.

After performing this main bagging, the resin is heated to the curing temperature of the prepreg layer A while maintaining this state, and the prepreg layer A is
The resin is cured while applying pressure from the inside.
In this case, since the linear expansion coefficient of the metal foils 4, 4 is sufficiently smaller than that of the mandrel 1, the mandrel 1
Even if the metal foils 4, 4 undergo thermal expansion, there is almost no elongation due to heat, and the metal foils 4, 4 are tightened from the outside with binding tape and are pressurized from the outside by the air pressure inside the tank. Since the metal foils 4, 4 do not escape to the outside, the pressure from the inside due to the thermal expansion of the mandrel 1
The metal foils 4, 4, which are tightened from the outside with binding tape, are tightened. Therefore, even if there are "wrinkles" in the metal foils 4, 4 covered with the prepreg layer A, the "wrinkles" will be smoothed out by the metal foils 4, 4 under tension when the resin is cured. The resin of the prepreg layer A is cured using the metal foils 4, 4 with the wrinkles smoothed out as an outer mold.

After that, wait for the resin of the prepreg layer A to harden, remove the backpack film 7 and the resin absorbing material 6, further remove the binding tape 5, peel off the metal foils 4, 4, and remove the hardened prepreg. Layer A, that is, the formed tube, is die-cut, and the end of the formed tube A' shown in FIG. 1f is finished cut to complete the CFRP tube.

That is, in this method of manufacturing a CFRP pipe, a plurality of metal foils 4, 4 having a coefficient of linear expansion sufficiently smaller than that of the mandrel 1 are wrapped around the side edges of the prepreg layer A wrapped around the mandrel 1. The metal foils 4, 4 are fastened to the prepreg layer A with binding tape 5, and a resin absorption material 6 is wrapped around the outside of the metal foils 4, 4 to cover the entire circumference of the prepreg layer A. This manufacturing method is characterized by removing residual air and surplus resin and curing the resin. In this manufacturing method, residual air and surplus resin in the prepreg layer A are removed through the lap portions of the metal foils 4, 4. Therefore, there is no need to provide holes in the metal foils 4, 4 to allow fluidized resin or air to pass through. There is no problem of leaving traces of tape fibers or holes of the perforated resin film. Moreover, in this manufacturing method, since the metal foils 4, 4 are made of materials whose coefficient of linear expansion is sufficiently smaller than that of the mandrel 1, even if the mandrel 1 thermally expands during resin curing, the metal foils 4, 4,
4 hardly elongates due to heat, so there are "wrinkles" in the metal foils 4, 4 covered with the prepreg layer A.
Even if there is, when the prepreg layer A is pressurized from the inside due to thermal expansion of the mandrel 1, the metal foils 4, 4 tightened from the outside by the binding tape 5
The "wrinkles" are smoothed out by the pressure applied from the inside. Therefore, the "wrinkles" of the CFRP pipes are stretched out by applying pressure from the inside. No traces of wrinkles remain.

Therefore, according to this CFRP pipe manufacturing method, it is possible to manufacture a CFRP pipe with a high quality shape with a smooth outer surface and a smooth inner surface. Since it can be removed through the lap part of the pipe, the strength of the manufactured CFRP pipe is sufficient.

In the above embodiment, before covering the outer periphery of the prepreg layer A wrapped around the Yamandrel 1 with metal foils 4, 4, temporary bagging is performed to remove most of the residual air and excess resin in the prepreg layer A. However, when the thickness of the prepreg layer A wound around the mandrel 1 is thin, such as when manufacturing a thin-walled tube, the temporary bagging may be omitted. In addition, in the above embodiment, the prepreg tape a is wrapped around the mandrel 1 until the thickness corresponds to the wall thickness of the CRRP pipe to be manufactured in one step. The winding of the tape a may be performed in multiple steps, and in that case, temporary bagging may be performed each time the prepreg tape a is wound to an appropriate thickness. In addition, when winding the prepreg tape and temporary bagging are repeated in this way, if the amount of prepreg tape wrapped at one time is small, the temporary bagging may be performed only by vacuum suction and heating. Furthermore, in the above embodiment, each half circumference of the prepreg layer A wound around the mandrel 1 is coated with two metal foils 4, 4, but when manufacturing a large diameter CFRP pipe, the entire prepreg layer is covered with two metal foils 4, 4. The circumference may be divided into two or more regions and each region may be covered with metal foil, and in that case, a layer slightly wider than the length obtained by dividing the circumference of this prepreg layer into multiple parts is placed on the outside of the prepreg layer. If a plurality of tape-shaped metal foils with a width of 100 mm are covered with each metal foil along the axial direction of the prepreg layer, and the side edges of each metal foil are wrapped around each other, residual air in the prepreg layer can be removed. Alternatively, residual air and excess resin can be removed through the laps of each metal foil. Also, long CFRP
When manufacturing a tube, the prepreg layer A may be divided into a plurality of regions in the length direction, and each region may be covered with metal foil by wrapping the edges so as to cover the entire length of the prepreg layer.

In addition, in the above example, a bleed type prepreg tape that requires blotting of excess resin is used, but in this invention, a CFRP pipe is manufactured using a non-bleed type prepreg tape that does not require blotting of excess resin. In that case, only the residual air in the prepreg layer A needs to be removed, so a breathable binding tape 5 is wrapped around the outer periphery of the metal foil 4 and the metal foil 4 is attached to the prepreg layer A. It is sufficient to perform bagging and curing of the resin with only the bolts tightened.

〔Effect of the invention〕

In this invention, a plurality of tape-shaped metal foils having a coefficient of linear expansion sufficiently smaller than that of the mandrel are placed on the outside of a prepreg layer wound around a mandrel, and the side edges of each metal foil are wrapped around each other to cover the entire circumference of the prepreg layer. This metal foil is fastened to the prepreg layer with binding tape, and residual air or residual air and excess resin in the prepreg layer are removed through the laps of each metal foil, and the resin is cured. Therefore, according to the present invention, it is possible to manufacture a CFRP pipe with a high quality shape and having a smooth outer surface with no unevenness.
In addition, residual air in the prepreg layer can be removed through the lap of each metal foil, making it possible to
The strength of the CFRP pipe is also sufficient.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention. Fig. 1 is a manufacturing process diagram of a CFRP pipe, Fig. 2 is a plan view showing a method of wrapping prepreg tape around a mandrel, and Fig. 3 is a diagram showing a method of winding a prepreg tape onto a prepreg layer. Fig. 4 is an enlarged sectional view of the prepreg layer covered with metal foil, and Fig. 5 is a plan view showing how to wrap the bonding tape around the outer periphery of the metal foil. It is. 1...Mandrel, a...Prepreg tape,
A... Prepreg layer, 2... Resin absorption material for temporary bagging, 3... Back pack film for temporary bagging, 4... Metal foil, 5... Bondage tape, 6...
Resin absorbing material, 7... Backpack film,
A′……Formed tube.

Claims (1)

[Claims] 1. After wrapping a prepreg tape made of a large number of carbon fibers aligned in the same direction and bonded with uncured thermosetting synthetic resin around the outer circumference of a mandrel made of a metal with a large coefficient of linear expansion, , a plurality of tape-shaped metal foils each having a width slightly wider than the length obtained by dividing the circumference of the prepreg layer into multiple pieces and having a linear expansion coefficient sufficiently smaller than that of the mandrel are arranged along the axial direction of the prepreg layer. Then, the side edges of each metal foil are wrapped with each other so that the entire circumference of the prepreg layer is covered with the metal foil, and a breathable bonding tape is wrapped around the outer circumference of the prepreg layer. It is tightened to the prepreg layer, and in this state, residual air or residual air and surplus resin in the prepreg layer are removed by vacuum suction through the lap portion of each metal foil and the binding tape, and then heated to the curing temperature of the resin. The resin is cured while pressurizing the prepreg layer from the inside by thermal expansion of the mandrel, and then the binding tape and metal foil are peeled off, and a molded tube is cut out from the mandrel. A method for manufacturing fiber reinforced synthetic resin pipes.