JPH08280860A - Manufacture of frp bat - Google Patents

Abstract

PURPOSE: To provide a method for manufacturing FRP bats which can easily make adjustment of the swing balance of a bat without influencing the characteristics of the bat even with repeated application of shocks with striking of balls. CONSTITUTION: In manufacturing FRP bats having an FRP shell filled with a foamed core material, a hollow bat body 2 is formed previously from an FRP material for molding, and foaming resin grains 7a, 7b having different specific gravities are injected sequentially in the hollow part in lamination in the longitudinal direction of the bat and are heated so that they are expansion-integrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing bats for baseballs and softballs, and in particular, F formed of a fiber reinforced plastic (hereinafter referred to as FRP) material.
The present invention relates to a method for manufacturing an RP bat.

[0002]

2. Description of the Related Art Conventionally, bats for baseball and softball have been mainly made of materials such as wood and metal, but in recent years, the toughness and rigidity required for bats have been high. In addition, FRP bats have become popular because they satisfy various characteristics such as repulsive force and can easily obtain a required shape.

Swing balance of the bat is one of the scales that express the characteristics of the bat. Even if the weight of the bat is the same, the swingability varies depending on the swing balance. Therefore, it is said that the criteria for selecting a bat suitable for each are the weight of the bat and the swing balance.

The FRP bat (hereinafter abbreviated as bat) is generally an external pressure molding method in which a prepreg is wound around a core material formed of a mandrel or foamed resin, and heat and pressure molding is performed in a mold. The outer circumference of the tube is covered with a prepreg, and the tube is molded by an internal pressure molding method or the like in which the tube is expanded and heated and pressed in a mold. Other recently, for example, coating a core material with reinforcing fibers and arranging it in a mold, injecting a molding resin material into a closed mold, and reacting and curing the molding resin material in the mold. Therefore, a RIM molding method for molding a bat has been proposed and used.

The bats formed by the above method have the same characteristics such as rigidity, strength and weight, and the same specifications. In order to adapt to the swing balance required for each bat, a prepreg is used at the time of bat formation. A mass body of lead or the like is placed between the layers, and the mass body is fixed at the same time as molding of the bat, or the mass body is mixed in advance with the core material made of polyurethane or other foaming resin when molding the bat. I was adjusting the swing balance.

Also, as disclosed in Japanese Utility Model Publication No. 50-44210 shown in FIG. 5, a hollow light metal body is provided with a polyurethane or other synthetic resin material 10a having a relatively large expansion ratio at the center of the striking portion. Then, another synthetic resin material 10b such as polyurethane having a relatively small expansion ratio is filled between the synthetic resin material 10a and the main body, and by appropriately selecting the ratio of these synthetic resin materials, the whole bat can be obtained. As shown in Japanese Utility Model Publication No. 62-23505 shown in FIG. 6 for determining the center of gravity and the weight thereof, the rod-shaped body 12 is provided inside the hitting portion of the foamed core material main body 11. A bat core material that is embedded in the core material body 11 in the axial direction is proposed in which the weight balance of the core material is adjusted by changing the density and shape of the rod-shaped bodies 12. It has become known.

[0007]

These conventional methods have the following drawbacks. That is, the bat must be safely used for a long period of time and maintained its durability even under the severe condition that a high impact force is applied at the time of hitting. However, at the time of bat molding, a mass body such as lead is arranged between the layers of the prepreg, and the mass body is fixed at the same time as the molding of the bat, or in the case where the mass body is mixed in the core material of the foam, Vibration caused by impact at the time of hitting for a long time may cause cracks in the resin of the FRP layer in which the mass body is arranged or the foam around the mass body mixed in the foam, and may cause noise. was there.

Further, a resin material 10a having a large expansion ratio is inserted in the center of the striking portion of the main body, and a synthetic resin material 10b having a small expansion ratio is filled between the synthetic resin material 10a and the main body. In the case where the rod-shaped bodies 12 having different specific gravities are embedded inside the material main body 11, since the foams having different specific gravities are separately foamed and combined, the specific gravities are different. There has been a problem that interfacial peeling or cracking is likely to occur at the boundary surface of the foam layer of the foam.

Therefore, in view of the above-mentioned problems of the prior art, the present invention can be realized by repeated impacts at the time of hitting a ball.
It is an object of the present invention to provide a method for manufacturing an FRP bat that can easily adjust the swing balance of the bat without affecting the characteristics of the bat.

[0010]

In order to achieve the above object, the method of manufacturing a FRP bat according to the present invention is, as a first method thereof, an FRP outer shell having a foamed core material inside.
In the method for manufacturing an RP bat, after a hollow bat body is previously formed from an FRP molding material, and expandable resin particles having different specific gravities are sequentially injected into the hollow portion in the longitudinal direction of the bat and laminated. Is a method for manufacturing an FRP bat, which is formed by heating and foaming and integrating the expandable resin particles.

As a second method, in a method for producing an FRP bat having a foamed core material inside an FRP outer shell, expandable resin particles having different specific gravities are previously prepared in a mold for molding the core material. After sequentially pouring and laminating in the longitudinal direction of the bat, the foamable resin particles are heated and integrated to form a foamed core material, and then an FRP molding material is formed on the outer peripheral portion of the foamed core material. Is a winding method, and is placed in a mold for bat molding, and then heated and pressure-molded.

The expandable resin particles used in the present invention are in a state before foaming so that foams having different specific gravities can be filled in desired positions in the longitudinal direction within the hollow portion of the bat body. It is preferably a granular solid, and for example, expandable polyvinylidene chloride resin particles, expandable polypropylene resin particles, expandable polystyrene resin particles and the like can be used in an unexpanded or preexpanded form.

[0013]

According to the FRP bat manufacturing method of the present invention,
Since foamable resin particles having different specific gravities are sequentially poured in the longitudinal direction of the bat and laminated, and then heat-foamed and integrated to fill a foam core material to form an FRP bat, The swing balance of the bat can be easily adjusted by adjusting the specific gravity and injection amount of the resin particles. Further, since the granular expandable resin particles are used as the material for forming the expanded core material, the expandable resin particles having different specific gravities can be accurately weighed, poured and laminated and arranged before foam molding. Therefore, at the boundary surface, the expandable resin particles having different specific gravities are mixed, and thereafter, the expandable resin particles having different specific gravities are integrated by foam molding, so that the foam having different specific gravities as in the conventional case is formed. It is possible to form a bat having excellent durability without causing interfacial peeling or cracking at the boundary surface of the layers.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external view of a bat made by the method of the present invention, and FIG. 2 is a sectional view taken along line AA ′ of FIG.
[Fig. 3] is an explanatory view showing the manufacturing method thereof. As shown in FIGS. 1 and 2, the bat 1 manufactured according to the present embodiment has F
It has a configuration in which a bat body 2 made of an RP outer shell and a foam core material 3 made of expandable polyvinylidene chloride resin particles filled in the hollow portion of the bat body 2 are arranged.
Further, the foamed core material 3 has a structure in which a specific gravity is large at a portion 4 on the tip side in the longitudinal direction of the bat, and a small specific gravity is formed at a portion 5 on the lower end side.

An example of manufacturing the FRP bat will be described below. First, a prepreg is wound and laminated on the outer peripheral portion of a substantially bat-shaped mandrel, and then the prepreg is placed in a bat-molding die and heated and pressed to form a hollow bat body 2.

Thereafter, as shown in FIG. 3, the bat body 2 is opened through the opening 6 formed on the tip side of the bat body 2.
The non-foamed expandable polyvinylidene chloride-based resin particles (hereinafter, abbreviated as resin particles 7) are injected into the hollow portion. At that time, in order to form the foamed core material 3 having a different specific gravity in the longitudinal direction of the bat in the hollow portion of the bat body 2,
The resin particles 7 have a relatively large specific gravity in advance.
a (specific gravity 0.9) and resin particles 7b having a relatively small specific gravity
Prepare one with a specific gravity different from (specific gravity 0.03). Then, first, the resin particles 7b (1,000
0 cc) is injected into the lower end of the hollow portion, and then resin particles 7a (200 cc) having a large specific gravity are injected into the upper portion of the resin particles 7b having a small specific gravity to be laminated.

Then, after closing the opening 6 of the bat body 2 with a plug member 8 or the like, the bat body 2 is placed in a furnace and heated from the outside to foam the resin particles 7a, 7b in the hollow portion. Thus, the inside of the hollow portion is filled with the foamed core materials 3 having different specific gravities to form the bat 1.

In the above embodiment, after the bat body 2 having a hollow structure is formed in advance, the resin particles 7 are poured into the hollow portion of the bat body 2 and laminated, and then heated to foam to form a foam core. Although the method of forming the material 3 is used, as another embodiment, as shown in FIG. 4, a mold 9 for molding the core material is used in advance, and the specific gravity is different in the mold 9 for molding the core material. After the expandable resin particles are sequentially injected in the longitudinal direction of the bat and laminated, the foamable resin particles are heated and foamed to be integrated to form a foamed core material, and then the outer peripheral portion of the foamed core material is formed. It is also possible to form a bat by winding and laminating the FRP molding material, placing it in a mold for bat molding, and heat-pressing.

In the foam core material 3 of the bat shown in the above embodiment, the specific gravity of the upper end side portion 4 and the lower end side portion 5 are different in the longitudinal direction of the bat. The specific gravity and injection amount of the resin particles 7 can be arbitrarily designed in consideration of the desired center of gravity or weight of the bat.

[0020]

As described above, according to the method of manufacturing the FRP bat of the present invention, the expandable resin particles having different specific gravities are laminated and injected in the longitudinal direction of the bat, and foamed and integrated to form the foamed core material. Method, the swing balance of the bat can be easily adjusted by adjusting the specific gravity and the injection amount of the expandable resin particles. Further, since the expandable resin particles having different specific gravities have an integrated structure by foam molding, there is no occurrence of interfacial peeling, cracking, etc. at the boundary surface of the foam layer as in the conventional case.

[Brief description of drawings]

FIG. 1 is an external view of a bat made by a manufacturing method of the present invention.

FIG. 2 is a sectional view taken along the line A-A ′.

FIG. 3 is an explanatory view showing a manufacturing process of the bat of the present embodiment.

FIG. 4 is an explanatory view showing a manufacturing process of a bat of another embodiment.

FIG. 5 is an explanatory view showing a conventional example.

FIG. 6 is an explanatory diagram showing a conventional example.

[Explanation of Codes] 1 Bat 2 Bat body 3 Foam core 4 Part on the tip side 5 Part on the lower end side 6 Opening 7 Resin particles 7a Resin particles with high specific gravity 7b Resin particles with low specific gravity 8 Plug member 9 Mold 10a Synthesis Resin material 10b Synthetic resin material 11 Core material body 12 Rod-shaped body

Claims (3)

[Claims] 1. A method of manufacturing a FRP bat having a foam core material inside a FRP outer shell, wherein a hollow bat body is previously formed from an FRP molding material, and a foamable resin having a different specific gravity in the hollow portion. Particles are sequentially poured in the longitudinal direction of the bat so as to be laminated, and then heated to form the foamable resin particles by foaming and integrating the FRs.
Method for manufacturing P bat. 2. A method for producing an FRP bat having a foamed core material inside an FRP outer shell, wherein expandable resin particles having different specific gravities are previously provided in a mold for molding the core material in the longitudinal direction of the bat. After being sequentially poured into each of the above and laminated, the foamable resin particles are heated and foamed to form a foamed core material, and thereafter, the FRP molding material is wound and laminated around the outer peripheral portion of the foamed core material. A method for manufacturing an FRP bat, which is characterized in that it is subsequently placed in a mold for bat molding and is heated and pressed. 3. The FRP according to claim 1, wherein the expandable resin particles are expandable polyvinylidene chloride resin particles, expandable polypropylene resin particles, and expandable polystyrene resin particles. Bat manufacturing method.