JPH0470917B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to a so-called glass fiber impregnated with a resin.
This invention relates to a baseball bat made of reinforced plastic that does not break and has the same deflection and flight distance as a wooden bat, and a method for manufacturing the same.

<Prior Art> Wooden bats are generally known as baseball bats, but recently, due to the lack of wood (resources), metal bats have appeared and become popular due to their emphasis on robustness. However, considering the material of metal bats, it is difficult to achieve the same flexibility as wood, and in recent years metal bats have been made thinner in order to extend flight distance.
Even if metal fatigue is not involved, many accidents resulting in breakage have become a problem.

In addition, recently, plastics have made remarkable progress, and a few attempts have been made to manufacture baseball bats made of reinforced plastics (FRP), but they have problems with strength and flexibility, and manufacturing methods that are especially suitable for mass production are not suitable. Therefore, it has not reached the stage of practical application.

For example, there is a baseball bat made of reinforced plastic disclosed in Japanese Patent Publication No. 49-28614, but this is simply a matter of inserting glass fibers such as pine in the gap between the shaped tube and the split mold to define the thickness of the bat. It is necessary to fill in an amount corresponding to the size of the gap to be formed, which is an extremely troublesome task. Moreover, the disadvantage of manufacturing this bat is that when finishing the reinforced plastic bat taken out of the mold, it is necessary to directly support both ends of the hollow bat body. This causes a blurring phenomenon, making it impossible to finish with precision. Of course, the wall thickness will not be uniform.

In addition, in the manufacturing method of baseball bats disclosed in Japanese Patent Publication No. 55-51584, glass fiber fabric with dense warp threads is made to have an uneven curve extending from the grip part, the ball hitting part, and the intermediate part (tapered part) of the bat. It is tedious to cut the batt into an expanded bat shape and then wrap the batt core material around each piece. Of course, in this case,
In order to create a structure wrapped in multiple sheets of glass fiber fabric, multiple sheets of paper patterns are required, making the process even more complicated and unsuitable for mass production. In addition, a structure in which a sheet is simply wrapped around the core body will be weak, or if the core body is made of a strong material, it will become too strong and it will not be possible to obtain the same flexibility as a wooden bat.

<Problems to be Solved by the Invention> In general, a baseball bat has a structure including a ball hitting part, a bending part, a tapered part in the middle, and a grip end part. Here, the problem with hollow bats is that the ball hitting part has a thick part that can withstand the impact of the ball, and the flexible part is in a state of instantaneous contact (so-called follow-through) when the ball hits the ball hitting part. If the deflection that produces the ball cannot be obtained, the flight distance will not be achieved, and the structure must necessarily be thinner than the ball-striking part. If you don't do that, you won't be able to get a flexibility similar to that of wood bats. However, the structure of the thick and thin parts must be of a simple type suitable for mass production.

In view of the above-mentioned circumstances, the present invention provides a circular knitted reinforcing material that can be used as a reinforced plastic base material, which can be easily fitted into a butt mold.
The purpose of the present invention is to provide a hollow reinforced plastic baseball bat that uses a woven glass fiber cylinder, simplifies the lamination work and finishing process of each part, and has a lightness and flexibility close to that of a wood bat, and a method for manufacturing the same. That is.

<Means for Solving the Problems> The reinforced plastic baseball bat, which is the first invention of the present invention, has a plurality of circular knitted or woven glass fiber cylinders that are laminated over the entire length of the bat. The glass fiber cylinders that are further stacked on the ball-hitting part are made of different lengths, and the stepped inclined part formed by the difference in length is made into a hollow reinforcing material buttshell, and the reinforcing material buttshell is made of polyester. It is impregnated with resin to form a hollow reinforced plastic butt body. In this case, the thickness of the ball-hitting portion is such that thick glass fiber cylinders are appropriately interposed and laminated between thin glass fiber cylinders to provide an impact-resistant structure.

The second invention is a method for manufacturing a baseball bat made of reinforced plastic, in which a glass fiber cylinder made of circular knitting, woven cylinder, etc. is held in a core mold having a roughly bat shape with rotating support parts at the front and rear ends. Insert multiple pieces over the entire length of the butt from the small diameter side, which is the part side, and
A process of laminating a hollow reinforcing material butt shell in which a tapered part is formed by stacking reinforcing glass fiber cylinders of different lengths that are further stacked on the ball-hitting part so that the end edges are stacked and sloped from the flexible part side. , an air venting step in which the reinforcing material butt shell is placed in a vacuum type tank and the inside thereof is evacuated, a resin impregnation step in which a predetermined resin is injected into the tank under pressure, and a resin-impregnated butt shell taken out from the tank. A drying process in which the mold is dried and fitted into a predetermined molding mother mold, and the mother mold is placed in a furnace for further drying, and the main body of the hollow reinforced plastic butt, which is formed by drying, is placed on a wood copying lathe while still in the core mold to give a surface finish. It consists of a processing step and a finishing step of removing the core mold from the hollow reinforced plastic bag body.

<Function> As mentioned above, by making the reinforcing material of the reinforced plastic batt into a circular knitted or woven glass fiber cylinder structure that is easy to fit into the core mold, the lamination can be done by simply fitting one after another into the core mold. By obtaining a butt shell and selecting the stacked number and tube length, each part of the bat (striking part, tapered part, flexible part, grip part, etc.) can be made to have the desired thickness, which in turn improves the finish of the bat and improves the user's taste. You will get a bat with effects that match your physical strength, and you will also be able to fly farther.

<Example> Hereinafter, the present invention will be described in detail based on the drawings of the example.

1 is a metal core mold in the shape of an elongated butt, which has a ball hitting part 1a which has a slightly smaller diameter as a whole than a bat product, and a flexible part 1c and a grip part 1d of the same small diameter, which are connected via a tapered part 1b. At the center of both ends of the core mold 1, there are bearing holes 2, which serve as rotation support parts.
2'. In this case, the flexible portion 1c and the grip portion 1d have the same diameter and are on the die-cut side (see Fig. 2).

Here, a wax-based mold release agent a is applied to the surface of the core mold 1, and a circular knitted glass fiber cylinder 3 knitted using yarn made of a plurality of glass fiber strands is attached to the outer periphery of the core mold 1 at the grip portion 1d. A plurality of pieces are sequentially fitted over the entire length of the butt, starting from the narrower diameter side, like putting on socks. In this case, the glass fiber cylindrical body 3 made of thin threads has a thickness of at most 2.
~ 3 sheets stacked. In this case, the glass fiber cylinder 3 serving as the base is provided with a folded portion 3e over the entire length of the core mold 1 and at the end of the ball hitting portion 1a on the resin injection side to prevent it from slipping off.

Next, in forming the thick wall portion 3a that will become the ball hitting portion, the ball hitting portion 1a and the tapered portion 1b of the core mold 1 are formed.
A plurality of glass fiber cylinders 3 having different lengths are fitted in order from the longest glass fiber cylinder 3, but at this time, one end of each group of glass fiber cylinders 3 is aligned with the end of the ball hitting portion 1a. If the edges of different lengths are made to face the tapered portion 1b side one after another, a stepped inclined portion 4 will inevitably be obtained there. That is, by simply fitting four to eight glass fiber cylinders 3 into the ball-hitting portion 1a, a hollow reinforcing material butt shell 5 having a desired taper 3b is obtained (see FIG. 5). In this case, the laminated structure of the glass fiber cylinder 3 is such that one or two layers of thick glass fiber cylinders 3' are interposed alternately between the thin glass fiber cylinder 3 and the butt weight and strength. The structure shall meet the requirements. Of course, the tips of the glass fiber cylinders 3, 3' in the thick portions also have a folded part 3e, similar to the base material, and the folded part 3e
Separate fixing flange pieces 8, 8' are used to fit the entire body from both ends to prevent it from being clamped and displaced.
In this case, the folding portion 3e has an appropriate number of cuts in the radial direction to facilitate folding. Incidentally, the glass fiber cylinders 3, 3' may be provided with longitudinal incision lines if necessary. This is particularly suitable for woven tube structures.

In this way, the hollow reinforcing material butt shell 5 is obtained by laminating an appropriate number of glass fiber cylinders 3, 3' on the core mold 1, and the outer periphery of the butt shell 5 is
Furthermore, one piece of glass fiber tape 6 is sequentially wound from the grip portion 1d side to cover the entire length, thereby tightening the lamination of the glass fiber cylinders 3, 3' and reinforcing the bending strength in the longitudinal direction (Fig. 6). reference).

After that, a plurality of reinforcing bat shells 5 with the core mold 1 are housed together in the air vent/resin injection tank 9 with the ball hitting part 3a side down, and the lid 9a is closed.
Close and seal. At this point, a vacuum pump (not shown) connected to the stopper 10 at the upper end of the tank 9 is driven to create a slight vacuum inside the tank and remove the fibers contained in the glass fiber cylinders 3 and 3' and the tape 6. Remove the air in between to ensure good resin impregnation.

Next, resin A made of polyester resin or the like is injected under pressure through the plug 11 placed at the bottom of the tank 9 (5
-6 atmospheres), and when the core mold 1 is taken out from the tank 9 after a predetermined period of time (for example, 1 hour), the reinforcing material butt shell 5 is impregnated with the resin A and becomes a reinforced plastic. Of course, when the resin A is injected under pressure, the fixed folded portion 3e of the reinforcing material butt shell 5 is placed downward to prevent curling up due to the pressure of the injected resin.

The reinforced plastic bag body 12 taken out from the tank 9 is left to dry for a while (it will be 70-80% dry in about 5-6 hours).

Next, this reinforced plastic bat main body 12 is fitted together with the core mold 1 into a metal bat molding mother mold 13 (see FIGS. 9A and 9B). In this case, the core mold 1 is supported on the end frame portion 13a of the molding mother mold 13 to ensure centering. Lightly press the molding mother mold 13, which will become the two-split mold, and close it using an appropriate stopper (not shown).
Fix it with.

After that, the molding matrix 13 is placed in a furnace (not shown) and heated slightly (at 80° C. for about 2 hours) to completely dry the reinforced plastic bag main body 12, thereby forming a solidified reinforced plastic bag main body 12. get.
In general, baseball bats vary in shape, weight, grip shape, etc., depending on the preference of the user, and as the level of baseball progresses, a wide variety of demands arise. Therefore, even when the bat body is completed using a mold, it is necessary to make modifications such as making the grip portion thinner or the ball hitting portion thinner to reduce the weight. This reshaping and finishing cutting will be carried out in the following operations.

That is, the bearing holes 2 and 2' provided at both ends of the core die 1 with the butt body 12 are inserted into the woodworking copying lathe 1, for example.
5, and the rotating shaft 16 is rotated. Here, large irregularities are cut in advance with a hand-held file, and then the outer surface of the bat body 12 is cut with a cutting whetstone 18 that moves following the pattern 17 of the bat model curve arranged on the side. Perform surface finishing. When cutting the plastic, water is poured from the water inlet 19 facing near the contact area of the cutting wheel 18 to ensure smooth cutting without scattering cutting powder.

Next, when the bat body 12 whose surface has been finished is tapped on one end of the core die 1 and pulled out from the grip portion 1d side, the bat body 12 will have a ball-striking part 12a with a larger diameter than the tip, a tapered part 12b, and a narrower part. Flexible part 1 of diameter
2c and a grip portion 12d of the same diameter. Of course, at this time, the fixing flange pieces 8, 8' are removed in advance. Since the bat main body 12 obtained in this way is formed to have a slightly longer length than the actual bat product, the front end and rear end where the folded part 3e is located are cut b as shown in FIG. 11A, and the bat head and grip end are Set to the length excluding. When cutting b, the butt body 12
is a little long, so if you move the cutting position back and forth,
The bat body 12 can be freely configured to suit the length of the ball-hitting part and the grip part, or to make the ball-hitting part short and the grip part long.

Finally, screw holes 20, 20 are formed in the head hole 12e and rear end hole 12f of this bat body 12, and a separately formed wooden or plastic cap 21 is inserted into the head hole 12e. If the grip end 22 is applied with adhesive and then screwed in and fixed, the baseball bat 12' made of reinforced plastic becomes sealed (hollow) as a whole. In this case, since the grip portion 12d still has a small diameter structure, a separate glass fiber tape 6' impregnated with resin is sequentially wound and overlapped so that the grip end 22 side has a large diameter. After the fiber tape 6' is solidified, it is tapered toward the grip end material to form the desired grip taper 12d' and grip end 22, thereby producing a bat product (see FIG. 15).

Example: Ball hitting part diameter 59mm, tapered part intermediate diameter 46mm,
The butt core mold has a bending part diameter of 24.5mm and a total length of 920mm.
A glass fiber cylinder with a diameter of 65 mm, a thickness of 0.2 mm, and a length of 920 mm is slightly shifted to one side so as to have a folded part of 15 mm at the end of the ball-hitting part, and two pieces are fitted over the entire length, and in this ball-hitting part, Length 290mm, 280mm,
Glass fiber cylinders of 270 mm, 260 mm, and 250 mm, and two thick glass fiber cylinders of length 285 mm and 275 mm are stacked alternately, and a string-shaped glass fiber of 50 mm width is wound over the entire length on the surface. Reinforced butt shell.
This reinforcing butt shell is placed together with the core mold in a tank with a lid for air venting and resin injection, and the tank is evacuated at one end to remove the air between the fibers.Then, the polyester resin is pressurized to 5 atmospheres in the tank. After 1 hour, the reinforcing material butt shell impregnated with resin was taken out and left in the atmosphere for 5 hours.
Once the reinforced plastic bag body is relatively dry, it is placed in a bat molding mold that will be split into two parts, and this molded mold is placed in a furnace and heated at 80℃ for 2 hours to solidify the reinforced plastic bag body. obtain. After that, the butt body was finished, and then the core mold was removed and the front and back ends were cut to form the 834mm butt main body, to which the 30g cap and 30g grip end were screwed together using adhesive. If, total length
864mm, ball hitting part diameter 65mm, tapered part intermediate diameter 49mm,
A butt product with a flexible portion diameter of 26 mm and a weight of 900 g was obtained.
In this case, the thickness of the flexible part was 2.5 mm, and the thickness of the ball hitting part was 6 mm, giving a degree of flexibility close to that of a wood bat.

<Effects of the Invention> As described above, the reinforced plastic baseball bat of the present invention and the method for manufacturing the same include directly stacking a plurality of glass fiber cylinders such as circular knits and woven tubes on a core mold, and further stacking them on the ball-hitting part. By using multiple glass fiber cylinders with different lengths, a reinforcing material buttshell with an inclined tapered part can be easily obtained when stacked, making it easy to form a buttshell and suitable for mass production. Good workability. Moreover, since this tapered part has a layered structure, the amount of resin that accumulates in the tapered part after resin impregnation is minimized, and it has a predetermined strength.
It will not cause cracks during use. In addition, in the case of the ball-hitting part, the reinforcing material itself is constructed by laminating an appropriate number of thick glass fiber cylinders, so the increased resin impregnation and the strength of the thick threads themselves combine to create a sufficiently impact-resistant structure. . In addition, since the flexible part has a thin structure made by stacking only a plurality of thin glass fiber cylinders, it has just the right amount of bending, making it possible to hit (foil-through) similar to a wood bat. Of course, this bat body is constructed to be slightly longer than the bat product, so by selecting the cutting position, a desired bat such as a bat with a slightly longer ball hitting portion or a bat with a slightly longer grip portion can be easily obtained.

Furthermore, since the surface finishing work of the reinforced plastic vat body, which is removed from the mold, is carried out with the core mold still attached, the vat body does not suffer from axial runout, has a uniform wall thickness, and achieves a highly accurate surface finish. can. Moreover, for this finishing cutting, a disk-shaped file or grindstone that is well suited for cutting reinforced plastics is used, and water is poured at this time, so it goes without saying that heat generation due to cutting does not occur, and it is not harmful to the human body. This results in smooth finishing work with no dust particles. In addition, since the cap and grip end portions disposed at the front and rear ends of the bat body, which is a bat product, are threaded together with adhesive, there is no separation even under severe impact.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a perspective view of the butt body, FIG. 2 is a side view of the core mold,
Figure 3 is a slope view of the glass fiber cylinder, Figure 4 is an explanatory diagram of the glass fiber cylinder stacked on the core mold, Figure 5 is an explanatory diagram of the formation of the ball hitting part and tapered part, and Figure 6 is reinforcement. A side view of the material butt shell, FIG. 7 is a sectional view of the folded part of the reinforcing material butt shell, FIGS. 8 A and B are illustrations of the butt shell accommodated in a tank and resin injection, and FIGS. 9 A and B are resin injection diagrams. 10 is an explanatory view showing the surface finishing process of the reinforced plastic butt body. FIGS. 11A and B are explanatory views of forming the butt body. Figure 12 is a partially cutaway side view of the cap, Figure 13 is a partially cutaway side view of the grip end, Figure 14 is a side view of the grip end and cap attached to the bat body, and Figure 1 is a side view of the grip end with the cap attached to the bat body.
FIG. 5 is an explanatory view showing the finishing process of the grip end. 1...Core mold, 1a...Ball hitting part, 1b...Tapered part, 1c...Flexible part, 1d...Grip part, 2, 2'...Bearing hole, 3...Glass fiber cylinder,
3′... Thick fiberglass cylinder body, 3e... Folded part,
4... Stacked sloped portion, 5... Hollow reinforcing material batt shell, 9... Tank, 12... Reinforced plastic butt body, 13... Butt molding matrix, 15...
...Lathe, 18...Cutting wheel, A...Resin.

Claims (1)

[Scope of Claims] 1. A plurality of glass fiber tubes such as circular knitting or woven tubes using yarns made of a plurality of glass fiber strands are overlapped over the entire length of the batt, and thick yarns of different lengths are further added to the ball hitting part. A glass fiber cylinder and a thin glass fiber cylinder are laminated with their tips aligned, the stacked slope formed on the tapered side edge is used as the taper part, and the entire length is wrapped with glass fiber tape to form a hollow reinforcing material butt shell. A baseball bat made of reinforced plastic, characterized in that the hollow reinforcement bat shell is impregnated and solidified with resin to provide a hollow reinforced plastic bat body. 2. A plurality of glass fiber cylinders made of circular knitting, woven tubes, etc. are fitted over the entire length of a bat-shaped core mold with rotating support parts at the front and rear ends, and glass fibers of different lengths are further overlapped on the ball-striking part. A process of stacking hollow reinforcing material butt shells to form a tapered part by stacking the ends of the fiber cylinders in stages so as to be inclined from the flexible part side, and a step of storing the reinforcing material butt shells in a tank and evacuating the inside to create a vacuum. a resin impregnation step in which the resin is then processed and injected into the tank, a drying step in which the resin-impregnated butt taken out from the tank is dried, fitted into a predetermined molding mold and dried in a furnace, and a hollow reinforcement formed by drying. A finishing process in which the plastic butt body is rotated while being inserted into the core mold, and the surface is cut while pouring water with a cutting wheel that follows the shape of the butt template curve, and the core mold is removed from the hollow reinforced plastic butt body. A method for manufacturing a baseball bat made of reinforced plastic, comprising a finishing step of removing the .