JPS649933B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing curved laminated tubes for frames of badminton rackets, tennis rackets, fishing nets, etc., or curved golf shafts, curved ski stocks, etc.

Conventionally, as a method for forming curved objects, resin-impregnated reinforcing fibers are covered with foamable synthetic resin or hollow rubber tubes, and the hollow tubes are formed by expansion pressure caused by foaming during heat molding or by expansion of the hollow tubes by pressurized air. An internal pressure molding method was adopted, and the reinforcing fibers impregnated with resin were in the form of braids, bag-like fabrics, or filament windings.

A similar method can be considered in principle to use a prepreg sheet as a reinforcing fiber impregnated with resin, but there are problems such as rupture of the sheet-winding product if it expands from inside.
The reality is that it has not been put into practical use.

The manufacturing method according to the present invention uses a core body having heat resistance, pressure resistance, and flexibility in the sheet winding method, and employs an external pressure forming method, so there are no problems such as those described above, and the sheet winding method does not have the above-mentioned problems. By appropriately adjusting the usage pattern, it is possible to manufacture curved laminated tubes (molded products) having arbitrary rigidity and elastic modulus, and it is possible to easily manufacture rackets, ball net frames, curved shafts, etc., and it is also advantageous. The products produced by this method are technologically progressive, such as being lightweight and having high strength because they make effective use of the strength and rigidity of fibers.

That is, in the manufacturing method of the present invention, a resin-impregnated prepreg sheet made of high-strength, high-modulus fibers is cut into a predetermined pattern, and then wrapped around a core having heat resistance, pressure resistance, and flexibility. wrapped or covered with shrink tape or shrink tube, then wrapped around the desired mold and fixed, heated and cured under external pressure as necessary, and after curing, the core is removed or left as necessary, prepreg sheet, core,
It is characterized by a clever combination of pressure and heating methods.

The high-strength, high-modulus fibers used in the present invention are one or two selected from long fibers such as carbon fibers, glass fibers, aromatic polyamide fibers, boron fibers, alumina fibers, and silicon coverite fibers. Combinations of more than one type are preferred, and examples of the form of prepreg sheets formed from such fibers include unidirectionally aligned sheets, woven fabrics, mats, and the like.

The resin impregnated into the sheet of the above-mentioned form is preferably a thermosetting resin such as an epoxy resin or a polyester resin.

The core body around which the resin-impregnated prepreg sheet is wound is a solid or hollow core body selected from metals such as steel, stainless steel, aluminum, and copper, and heat-resistant synthetic resins such as polyester, nylon, polypropylene, and Teflon. A rod-shaped material having heat resistance, pressure resistance, and flexibility may be used.

Further, the cross-sectional shape of the core can be arbitrarily determined depending on the purpose, such as a circle, an ellipse, a square, or a concave shape.

In short, the core has a rod-like shape that has enough flexibility to bend into a desired shape after wrapping the prepreg sheet, and has heat and pressure resistance that prevents the core from buckling during heat and pressure molding. Any material can be used.

Furthermore, in the case of a hollow body, if necessary, a core rod may be inserted in the center and a prepreg sheet may be wrapped around the body, and a tube-shaped body that is easily bent may also be used. A solid core can be pulled out after curve forming and only the formed laminated tube can be used. However, when using a hollow core, the core can be pulled out after curve forming and only the formed laminated tube can be used. It is also possible to leave the core in the range where there is no problem in terms of physical properties and weight and use it as a composite laminated pipe.

As such a hollow core, an FRP tube is suitable, but a synthetic resin tube such as polyester or nylon may also be used.

In order to pull out the core, a release agent is applied to the core, and Teflon tubes have particularly good release properties and can be preferably used.

When the resin-impregnated prepreg wound around the core is heat-molded without applying pressure, the volatile matter in the prepreg and the thermal expansion of the air trapped between the laminated sheets cause
This causes phenomena such as frequent occurrence of voids and peeling, making it difficult to obtain a curved laminated pipe with high strength.

In the present invention, the above problem is solved by the shrinkage pressure generated during heating by wrapping shrink tape, shrink tube, etc. It is possible to further improve the quality, shape, and accuracy by using these in combination.

Shrink tapes and tubes can be made from cellophane, polypropylene, polyester, nylon,
Heat-shrinkable tapes or tubes made of synthetic resin that can withstand the heat molding conditions of polyvinyl chloride and the like are desirable.

In addition, tubes made of silicone rubber or synthetic rubber can be used as means for tightening the resin-impregnated reinforcing fiber tubular material and prepreg coated on the core body, and air pressure is applied to the tube with a diameter smaller than the outer diameter of the tubular material coated on the core body. to inflate the tube to a value greater than the outer diameter of the tube.
A collapsible tube may also be preferably used, in which a core covered with a tubular material is inserted into the tube in this state, and then the air pressure is released to utilize the elastic contraction pressure generated when the tube contracts.

In the present invention, the prepreg laminate covered with the above-mentioned shrink tape or shrink tube is put into a mold as it is, or is bent and heat-cured without using a mold,
It is very convenient in that a desired molded product can be obtained.

However, it is also possible to perform molding that can apply pressure to further improve quality, shape, and precision.
A high degree of dimensional accuracy can be achieved as required.

In addition to pressing with a mold, external pressure can be applied by inserting a material with a high coefficient of linear expansion such as rubber into the mold and utilizing linear expansion pressure, or by using air pressure or steam pressure by the autoclave method. It is.

In addition, when winding the resin-impregnated prepreg sheet mentioned above around the core, if the prepreg sheet is a unidirectionally aligned sheet, the fibers are arranged in a direction parallel to the axis of the core and bent. This may cause fiber disorder, so it is desirable to wind at least the outermost layer so that the fiber direction makes an appropriate angle with the axis of the core.

Examples of the present invention will be described below.

[Example 1] A unidirectionally aligned sheet prepreg of carbon fiber impregnated with an epoxy resin is cut into a predetermined pattern.

On the other hand, a core bar is inserted into a thick Teflon tube with pressure resistance to keep it straight.
Apply mold release material and sheet temporary fixing resin to the tube surface.

After winding the pattern-cut sheet prepreg around the Teflon tube, wrap it with heat-shrinkable polypropylene tape under moderate tension, remove the core, and insert a flexible core wire in its place. Using this, the tube with the sheet wrapped around it is wrapped and fixed around a cylindrical mold with grooves on its side.

Next, this was heated and cured in a furnace under predetermined conditions, and then removed from the mold, the Teflon tube was pulled out, and the polypropylene tape on the surface was removed to obtain a carbon fiber resin laminated tube curved into a circular shape.

When the surface of the laminated tube thus obtained is polished and painted, it becomes a material that has an excellent appearance, is lightweight, has high strength, and has high elasticity and can be used as frames for fishing nets, badminton rackets, etc.

[Example 2] In Example 1 above, if a glass cloth/phenolic resin flexible FRP tube is used instead of the core Teflon tube, a lightweight composite laminate can be created without pulling out the core tube. It is possible to manufacture curved frames of tubes.

Since the present invention employs the method described above, there is no rupture of sheet winding products, which was a problem in internal pressure molding, and it is possible to mold extremely stable curved laminated tubes. By adjusting the usage pattern appropriately, curved laminated tubes with arbitrary rigidity and elastic modulus can be manufactured, and can be used for frames of fishing nets, badminton rackets, tennis rackets, etc., as well as bicycles. It can be used for various purposes such as frames, automobile parts, furniture, and curved golf shafts.

Claims (1)

[Claims] 1. A resin-impregnated prepreg sheet made of high-strength, high-modulus fibers is cut into a predetermined pattern, and then wrapped around a core having heat resistance, pressure resistance, and flexibility,
Wrap or cover the peripheral surface with shrink tape or a shrink tube, then wrap it around a desired mold and fix it, heat and cure it under external pressure if necessary, and after curing, remove the core or leave it as necessary. A method for manufacturing a curved laminated pipe characterized by: 2. A patent in which the above-mentioned high-strength, high-modulus fiber is made of one or a combination of two or more selected from carbon fiber, glass fiber, aromatic polyamide fiber, boron fiber, alumina fiber, and silicon carbide fiber. A method for manufacturing a curved laminated pipe according to claim 1. 3. The method for manufacturing a curved laminated pipe according to claim 1 or 2, wherein a resin selected from epoxy resin, polyester resin, and phenolic resin is used as the impregnating resin. 4. A method for manufacturing a curved laminated pipe according to claim 1, 2, or 3, using a sheet-like material made of a unidirectionally aligned fiber sheet, woven fabric, or mat as the impregnated prepreg sheet. . 5. The curved laminated pipe according to claim 1 or 2 or 3 or 4, in which a solid or hollow rod-shaped body selected from metal, FRP, and synthetic resin is used as the core body. manufacturing method. 6 Claims 1, 2, or 3 in which a tape or tube selected from cellophane, polypropylene, polyester, nylon, silicone rubber, synthetic rubber, and polyvinyl chloride is used as the shrink tape or tube. or fourth
5. A method for manufacturing a curved laminated pipe according to item 5. 7 Claims 1 or 2 or 3 or 4 in which pressure by a mold, linear expansion pressure of rubber, etc., air pressure, etc. are used as the means for applying the external pressure.
A method for manufacturing a curved laminated pipe according to item 5 or 6.