JP2000288127A - Racket and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a racket manufacturing method obtaining a molding stable in quality and laterally well-balanced by applying a uniform and sufficient pressure into a flexible tube to be a core material. SOLUTION: This racket manufacturing method uses an internal pressure molding method of laminating fiber reinforced resin prepreg on the outer periphery of a flexible tube to form a premolding 1, disposing the premolding 1 in a die 2 and then injecting gas in the tube to press the premolding 1 to the inner surface of the die 2. Openings are provided at both ends of the flexible tube. Both openigns 3 are placed in line with each other so as to form a racket grip part, and circular arc shape is formed between the openings 3 so as to form a frame part 5, thus forming the premolding 1. The die 2 is pressurized and heated, and gas is injected from both sides of the openings 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber reinforced resin racket using an internal pressure molding method and a method for producing the same.

[0002]

2. Description of the Related Art Regarding a method of manufacturing a fiber reinforced resin racket used for tennis, squash, badminton, etc.,
Using a flexible tube as the core material, laminating a fiber reinforced resin prepreg on its outer periphery and placing it in a mold, sending compressed air into the tube and pressing the molding material against the mold to form an internal pressure that forms a racket There is generally known a molding method and an external pressure molding method in which a material formed in advance into a substantially racket frame shape from a hard foamed resin or the like is used as a core material, a fiber reinforced resin prepreg is laminated on the outer periphery, placed in a mold, and pressed. Have been.

Here, a conventional internal pressure forming method is shown in FIG. 3, in which compressed air is fed from an opening 3 at one end of a flexible tube 1 which constitutes a grip portion 4 of a racket. Arrow) On the other hand, the opening 3 at the other end of the tube
a was bent and sandwiched between the molds 2 so as to eliminate air leakage and to mold.

However, in such a conventional internal pressure molding method, sufficient pressure is applied to the tube near the side where the compressed air is supplied, but the pressure decreases in the portion near the closed tube end on the opposite side. Not enough molding pressure is obtained,
For example, a shift may occur in the laminated fiber reinforced resin prepreg, and a crack may be formed between layers. In order to reduce the weight while securing the strength of the racket, it is effective to increase the fiber content of the fiber-reinforced resin to reduce the resin component, but if the molding pressure is not sufficient, the resin of the laminated prepreg is not sufficient. There was a problem that they did not integrate with each other. In particular, fiber-reinforced resins and organic fibers with high elastic modulus,
When a reinforcing material such as amorphous fiber is used, or when a metal plate is inserted into a grip to increase rigidity, the hardness and properties of the materials are different, and the adhesiveness to the prepreg during molding and the displacement between layers are caused. Was sometimes a problem.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention is not only capable of obtaining a stable molded product by applying uniform and sufficient pressure to a flexible tube serving as a core material,
An object of the present invention is to provide a manufacturing method capable of manufacturing a racket in which left and right balance is achieved.

[0006]

The present invention has been made to solve the above problems, and the gist of the racket manufacturing method of the present invention is as follows. That is, a fiber-reinforced resin prepreg is laminated on the outer periphery of a flexible tube serving as a core material to form a preform, and after the preform is disposed in a mold, a gas is inserted into the flexible tube. A method of manufacturing a racket using an internal pressure molding method in which a preform is pressed against an inner surface of a mold, wherein openings are provided at both ends of a flexible tube, and the opening of the opening is formed so as to constitute a grip portion of the racket. Manufacture of a racket in which both are arranged side by side and an arc is formed between the openings so as to form a frame portion, a preform is formed, a mold is heated under pressure, and gas is inserted from the openings at both ends. Pertains to the method.

Preferably, the fiber content of the fiber reinforced resin prepreg forming a part of the preform is 65% by weight or more and 75% by weight or less, and the preform is located at a position symmetrical to the left and right of the preform. A prepreg of at least one type different from a fiber reinforced resin prepreg forming a part of a molded article is disposed. Further, a metal material is arranged at a position symmetrical to the left and right of the preform, and particularly, the metal material is arranged at least at a position constituting a grip portion of the racket.

The gist of the racket of the present invention is a characteristic racket obtained by the above-described manufacturing method, in which a flexible tube penetrating a frame portion and a grip portion expands substantially symmetrically on the left and right sides of the racket. Pertaining to rackets that are

[0009]

The most important feature of the manufacturing method of the present invention is that an opening is provided at both ends of a flexible tube, and gas is inserted from both sides of the opening. Therefore, a uniform and sufficient pressure can be applied to the entire area inside the tube. Also, the tube must not only be flexible, but must withstand the pressure and heating in the mold. Therefore, the material of the tube is flexible and should be above 150 ° C., preferably 180 ° C.
The material must be able to withstand temperatures of at least ℃. Examples of such a material include a polyamide resin, a polyester resin, a fluororesin, and butyl rubber used for a tire tube.

[0010] The fiber reinforced resin prepreg laminated on the outer periphery of the flexible tube as the core material is a main component that forms substantially the entire racket frame. Usually, about four to six layers are laminated. . However, according to the production method of the present invention, uniform and sufficient pressure can be applied to the flexible tube of the core material. Since it is difficult for a shift to occur and a crack is hardly generated between the laminations, for example, about eight to ten layers can be laminated. The prepreg is preferably a unidirectional fiber reinforced resin prepreg, and its fiber content is usually 5%.
It is from 0% by weight to 60% by weight. However, according to the production method of the present invention, the resin component is small and the fiber content is 60% by weight or more, particularly 65% by weight for the same reason as described above.
Even in the case of not less than 75% by weight, there is no problem that the laminated prepregs are not integrated,
The racket can be reduced in weight.

The reinforcing fibers and resin in the fiber-reinforced resin prepreg used in the present invention are not particularly limited as long as they are commonly used for rackets. That is, as the reinforcing fibers, for example, inorganic fibers such as carbon fibers and glass fibers, and at least one kind of organic fibers such as aramid fibers and high-tensile polyethylene fibers can be used.As the resin, for example, an epoxy resin and an unsaturated polyester Thermosetting resins such as resins and vinyl ester resins can be used alone or in combination.

According to the production method of the present invention, a preform is formed by laminating the core material (flexible tube) and a fiber-reinforced resin prepreg. The openings at both ends of the flexible tube are arranged side by side to form the grip portion of the racket, and the frame portion is formed in an arc shape except for the vicinity of the opening serving as the grip portion. A mouthpiece is attached to the opening of the flexible tube of the preform placed in the mold, and is connected to a pipe for sending compressed air.

The mold is set on a steam press, and the preform is heated under pressure and gas is inserted into the flexible tube. That is, immediately after the mold is press-fixed by the steam press machine, the compressed air opening valve is opened to expand the flexible tube, and the preform is pressed into the mold to perform molding. Press temperature is 1
The temperature is 10 ° C. to 165 ° C., and heating is performed for about 10 to 30 minutes until the resin of the fiber reinforced resin is cured. Since the heating temperature and the curing time vary depending on the resin impregnated in the fiber, they are adjusted according to the resin used. The pressure to be applied is not particularly limited, and may be a pressure that does not cause the mold lid to rise or move due to the air pressure supplied to the tube or the flow of the resin. Further, the pressure in the tube during molding is 1 kg / cm2 to 10 kg / cm2.
According to the present invention, there is no particular problem even if the pressure is set higher than the general pressure of 4 kg / cm2 to 5 kg / cm2.

In order to reinforce the racket symmetrically in the preform, the preform should be symmetrically positioned in the preform.
At least one or more layers of a prepreg of a type different from the above-mentioned fiber-reinforced resin prepreg which forms a part of the preform can be arranged. The arrangement place is arranged as needed on the frame portion, the grip portion, or the like, and may be on the preform or between layers. Here, different types of prepregs mainly mean different properties, for example, those using fiber reinforced resin having a relatively high elastic modulus, reinforced fibers such as organic fibers for inorganic fibers and amorphous fibers.

Further, for the same reason as described above, a metal material can be disposed. The metal material is used particularly when it is arranged in a grip portion or the like to increase rigidity. As the metal material, for example, a thin plate of a titanium alloy, an amorphous metal plate, or the like is used. In the present invention, it is possible to use a prepreg or a metal material of a different type from the fiber-reinforced resin prepreg which forms a part of the preform, because the whole is uniformly and sufficiently pressed during the molding. This is because displacement between the inner layers is less likely to occur and interlayer adhesion is improved. Therefore, there is no problem in the adhesiveness or displacement with the prepreg due to the difference in hardness and properties of the material of the preform.

According to the production method of the present invention, a preform in which a tubular continuous fiber is arranged in a flexible tube is placed in a mold, and a resin is injected into the mold to fill the resin into the continuous fiber. It goes without saying that the present invention can be directly applied to a method of manufacturing a racket by the so-called RTM method of impregnating and performing internal pressure molding.

[0017]

The present invention will be described in more detail with reference to the following examples. A flexible tube serving as a core material is made of nylon and has a thickness of 70 μm. A unidirectional fiber reinforced resin prepreg containing a carbon fiber having an elasticity of 24 ton is used as a fiber reinforced resin prepreg laminated on the outer periphery thereof. It was used as a preform. The carbon fiber content was 60%.
The first embodiment has a weight percent of 70% by weight, the second embodiment has a weight of 70% by weight, and the third embodiment has a thin plate of a titanium alloy inserted between carbon fiber reinforced resin prepreg layers in the grip portion. The resins used are all epoxy resins.

In each embodiment, five layers of the above-described unidirectional fiber reinforced resin prepreg are laminated, and caps for sending compressed air are attached to both ends of the flexible tube. Then, the temperature of the steam press is set to 145 ° C, and the mold is preheated to 100 ° C. When the lid of the mold is opened and a nylon tube 1 (preformed body) on which a carbon fiber reinforced resin prepreg is laminated is set in a mold 2 as shown in FIG. The mounting portion) is aligned to form an end of the racket grip portion 4 and a space between the openings forms the frame portion 5.

Subsequently, the mold lid is closed and pressurized and heated by a steam press to perform molding. When the steam press is closed and sufficient pressure is applied to the mold, the compressed air valve is opened. Send compressed air into the nylon tube (arrow). Then, pressure is applied from both ends in the tube, and the air pressure in the tube is 7.0 kg / cm.
2 is uniform. Then, pressure molding is performed at a mold temperature of 130 ° C. for 30 minutes.

On the other hand, as shown in FIG. 3, the same material as described above except that the base is attached only to the opening 3 at one end of the nylon tube 1, and the opening 3 a at the other end is bent and sandwiched in the mold 2. The molding conditions (conventional internal pressure molding method) were taken as a comparative example (conventional example), and compared with an example of a method of forming a racket by feeding compressed air from both ends of the tube (a manufacturing method of the present invention). . Note that Comparative Examples 1 to 3 correspond to Examples 1 to 3, respectively.

The finish of the racket molded under each condition was cut at the grip portion near the end of the tube, and the state of lamination of the carbon fiber reinforced resin was observed. The results are shown in the table of FIG. As shown in FIG. 2, all of the examples obtained better results than the comparative example. In particular, when the fiber content was 70% by weight (Example 2), when the titanium sheet was inserted (Example 2). Even in the case of 3), since the molding is favorably performed, it is understood that the racket excellent in quality, which is balanced in the left and right, can be formed by the manufacturing method of the present invention.

[0022]

As described above, according to the present invention, in the internal pressure molding method of a racket, since compressed air is fed from both ends of the tube, uniform and sufficient pressure can be applied to the core tube, and the left and right balance can be achieved. It is possible to obtain a molded product which is stable in quality. In particular, when a prepreg with a low resin content (high fiber content) is used or when a thin metal plate is inserted, the more difficult it is to mold using the conventional manufacturing method, the better the molding state is, and a high quality racket is manufactured. The racket can be reduced in weight and rigidity can be improved.

[Brief description of the drawings]

FIG. 1 is a top view showing a state in which a preform of the present invention is arranged in a mold.

FIG. 2 is a table comparing the cross-sectional states of a racket formed by a manufacturing method of the present invention and a conventional manufacturing method.

FIG. 3 is a top view showing a state in which a preform according to a conventional method is arranged in a mold.

[Explanation of symbols]

 1 Preformed body 2 Mold 3 3a Flexible tube opening 4 Grip 5 Frame

Continuing on the front page F-term (reference) 4F205 AA29 AA36 AD03 AD12 AD16 AD18 AD19 AD25 AH59 AM26 AR20 HA08 HA25 HA33 HA37 HA40 HA45 HB01 HC02 HC17 HE06 HF05 HG03 HK02 HK03 HK04 HK05 HK16 HK19 HK26 HK28 HK31 AHTA4A03 HT03 AD16 AD18 AD19 AD25 AH59 AM26 AR20 LA02 LB01 LB11 LD15 LG04 LG06 LG38 LH02 LH06 LH13 LH18 LJ01 LJ29 LN09 LW01 LW06 LW26

Claims (6)

[Claims] 1. A preform is formed by laminating a fiber-reinforced resin prepreg on the outer periphery of a flexible tube serving as a core material, and after placing the preform in a mold, a gas is introduced into the flexible tube. A racket manufacturing method using an internal pressure molding method of pressing the pre-formed body against the inner surface of the mold by inserting a
Openings are provided at both ends of the flexible tube in the preform, and both of the openings are arranged side by side so as to form a grip portion of a racket, and the openings are arranged in an arc shape so as to form a frame portion. A method for manufacturing a racket, comprising heating a mold under pressure and injecting gas from the openings at both ends. 2. A fiber reinforced resin prepreg forming a part of the preform has a fiber content of 65% by weight or more and 75% by weight or more.
The method for producing a racket according to claim 1, wherein the content is not more than% by weight. 3. The prepreg according to claim 1, wherein at least one layer of a prepreg of a type different from a fiber-reinforced resin prepreg forming a part of the preform is arranged at a position symmetrical to the left and right of the preform. Racket manufacturing method. 4. The racket manufacturing method according to claim 1, wherein a metal material is disposed at a position symmetrical to the left and right of the preform. 5. The racket manufacturing method according to claim 1, wherein a metal material is disposed at least at a position constituting a grip portion of the racket. 6. A racket obtained by the manufacturing method according to claim 1, wherein the flexible tube penetrating the frame portion and the grip portion expands substantially symmetrically on the left and right sides of the racket. .