JP2007044335A - Bat and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enlarge a sweet spot area, improve a shock-absorbing characteristic, improve strength by uniformizing the thickness of a bat body, lighten its weight and provide a satisfactory swing balance. <P>SOLUTION: This bat comprises the bat body 2, and a foam core material 3 formed in its inside space 2A. The foam core material 3 is formed by filling inside the bat body 2 with the interior content of approximately 100% of methacrylic resin foam beads 15 treated with a prescribed foaming process and heating and secondarily foaming it with the inside space 2A closed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a bat body is formed using a metal material or fiber-reinforced plastic (FRP) made of aluminum, titanium, or an alloy thereof, and a foam core material is formed inside the bat body using a foam resin. The present invention relates to a baseball or softball bat and a manufacturing method thereof.

Baseball and softball bats are mainly made of wood, FRP or metal, especially for amateurs. Such bats have a method of filling a hollow bat body with a resin core material for the purpose of enhancing mechanical rigidity, shock absorption characteristics, etc., and controlling swing balance. ing.
For example, in Patent Document 1, an FRP bat body is filled with expandable polyvinylidene chloride resin particles, expandable polypropylene resin particles, or expandable polystyrene resin particles to control swing balance. . In Patent Document 2, repulsion characteristics equivalent to those of a wooden bat are obtained by filling a foam body such as dicyclopentadiene (DCPD) resin inside an aluminum bat body.
JP-A-8-280860 JP 2001-79132 A

In the FRP bat described in Patent Document 1, the swing balance is adjusted by adjusting the specific gravity and the injection amount of the expandable resin particles.
However, the expandable resin particles used as the core material of the FRP bat have such characteristics that the foaming force is weak and the hardness is small. Therefore, the FRP bat has a problem that a practical bat cannot be obtained because the resin core material becomes heavy when the expansion ratio is lowered in order to increase the hardness. In addition, the FRP bat has a problem that the use of such expandable resin particles makes it impossible to increase the ball flight distance or the effective hitting area, that is, the sweet spot area or to improve the impact absorption.
On the other hand, the aluminum bat described in Patent Document 2 has substantially the same repulsion characteristics and shock absorption as the wooden bat. By the way, in an aluminum bat, the bat body is generally manufactured by a swaging molding process in a cold state, but there is a problem that the thickness of the grip portion increases from the tapered portion, the weight is increased, and the balance is deteriorated. Therefore, the aluminum bat can be reduced in thickness by, for example, subjecting the region from the tapered portion to the grip portion in advance to a grinding process and then performing a swaging process.
However, in such an aluminum bat, there is a problem that the mechanical strength is reduced by scratching the raw aluminum tube by grinding. In addition, in aluminum bats, the grinding amount must be precisely controlled to satisfy the reference value, and grinding must be performed, and the corresponding area of the tapered portion is ground stepwise, resulting in steps. There was also a problem of end.
Accordingly, the present invention solves the above-mentioned problems of the conventional FRP butt aluminum bat, expands the sweet spot area and improves the shock absorption characteristics, and makes the bat main body uniform to improve the strength. The present invention has been proposed for the purpose of providing a bat that can be made lighter and obtains a good swing balance and a manufacturing method thereof.

The bat according to the present invention that achieves the above-described object includes a bat main body and a foamed core material formed of expandable resin beads filled in the internal space. In the bat according to the present invention, the bat main body is made of a metal material or a fiber reinforced plastic made of aluminum or an alloy thereof, titanium or an alloy thereof, and the entire end portion is closed and an opening is provided at the grip end. It is formed in a cylindrical body having a substantially bottomed long axis, and foamable resin beads are filled into the internal space from the opening. In the bat according to the present invention, foamed methacrylic resin beads subjected to a predetermined foaming treatment are used as expandable resin beads, and the internal space of the bat body is filled with an internal volume of approximately 100%. In the bat according to the present invention, the foam core material is formed by subjecting the bat main body in which the opening portion is closed and the internal space is sealed to heat treatment to expand the expanded methacrylic resin beads.
According to the vat according to the present invention, the expanded methacrylic resin beads forming the expanded core material may be formed of a conventional foaming resin such as a foaming vinylidene resin, a foaming polypropylene resin, or a foaming polystyrene resin. In comparison, it has large foaming properties, hardness or light weight. The expanded methacrylic resin beads have a hardness of about 1.8 times and a weight of about 0.7 times in the same volume as compared to, for example, an expandable vinylidene resin, and reduce the filling amount to reduce the weight. A secondary foaming process is performed by a heat treatment at a relatively low temperature for a short time after filling to obtain a large internal pressure on the bat body.
According to the bat of the present invention, the foam core material formed by the foamed methacrylic resin beads reduces the weight and expands the sweet spot area by applying a constant pressure to the bat main body from the inside, and absorbs the impact. Increase properties.

  Also, the manufacturing method of the bat according to the present invention that achieves the above-described object is to close the tip portion using a metal material or a fiber reinforced plastic made of aluminum, an alloy thereof, titanium or an alloy thereof, and an opening at the grip end. The bat main body formed in a cylindrical body having a substantially bottomed long axis and the foam core material formed by the foamable resin beads filled in the internal space of the bat main body. As described above, a vat is manufactured using foamed methacrylic resin beads subjected to a predetermined foaming treatment. The bat manufacturing method according to the present invention includes a step of filling expanded methacrylic resin beads with an internal volume of approximately 100% from the opening on the grip portion side into the internal space of the bat body, and a plug member in the opening on the grip portion side. The inner space of the bat main body is configured as a sealed space portion by fitting and fixing, and the foamed methacrylic resin beads are secondarily foamed in the inner space by subjecting the bat main body to a heat treatment.

  Furthermore, in the manufacturing method of the bat according to the present invention, the manufacturing process of the bat main body includes a cylindrical material forming process, a spinning rolling process, and a swaging process, and has a predetermined shape having an opening in the grip part. Form the bat body. The bat manufacturing method according to the present invention forms a bottomed cylindrical cylindrical material using a material in the manufacturing process of the bat body. The manufacturing method of a bat according to the present invention is a spinning method in which a cored bar is inserted into an inner hole of a cylindrical material and a plurality of rolling rollers arranged at different positions in the circumferential direction are pressed against the outer peripheral portion. By performing the rolling process, a bat main body material having a predetermined thickness in the corresponding region of the grip portion is formed. The manufacturing method of a bat according to the present invention includes a bat body having a predetermined shape in which a grip portion and a sweet spot portion are connected by a continuous surface via a tapered portion by performing a cold swaging process on a bat body material. Form.

  According to the bat manufacturing method of the present invention, the expanded methacrylic resin beads used as the material of the expanded core material are generally used expandable resins such as expandable vinylidene resins, expandable polypropylene resins or expandable resins. Compared to polystyrene resin, it has large foaming properties and hardness or light weight properties. For example, compared with expandable vinylidene resin, the hardness in the same volume is about 1.8 times and the weight is about 0.7. Is double. According to the manufacturing method of the bat according to the present invention, the foamed methacrylic resin beads are foamed in a predetermined foaming process, for example, about 20 times, and the bat body is filled with an internal volume of approximately 100%, thereby reducing the filling amount and reducing the weight. To make it easier. According to the manufacturing method of the bat according to the present invention, the plug member is fixed to the opening on the grip portion side, and heat treatment is performed in a state where the internal space of the bat main body is a sealed space portion, so that the expanded methacrylic resin beads are secondary. Since foaming is performed, a re-foaming process is performed by a heat treatment at a relatively low temperature for a short time, and a large internal pressure on the bat body can be obtained. According to the bat manufacturing method of the present invention, the bat body is subjected to a large constant pressure from the inside due to the foamed core material, so that the sweet spot region is expanded and the impact absorption characteristics are enhanced. To manufacture.

  Further, according to the bat manufacturing method of the present invention, in the spinning rolling process, the core metal is inserted into the inner hole of the cylindrical material, and the outer peripheral portion is rotated in three directions while rotating at a speed of, for example, 300 rpm to 600 rpm. The rolling roller is pressed simultaneously, and the bat body material is formed by rolling in the axial direction while making the material in close contact with the cored bar and drawing. According to the bat manufacturing method of the present invention, by controlling the pressing operation of the rolling roller against the cylindrical material by the controller, the corresponding region of the grip portion is ideal over the entire axial length without becoming thick. A bat body material having an appropriate thickness is formed. According to the bat manufacturing method of the present invention, the bat body material is subjected to cold swaging to form a bat body having a predetermined shape in which the grip portion and the sweet spot portion are continuous via the taper portion. To do. According to the manufacturing method of the bat according to the present invention, the bat main body is formed with a predetermined thickness over the whole, so that weight reduction and good balance can be achieved and high strength can be achieved.

 According to the present invention configured as described above, a predetermined foaming treatment is performed on the internal space of the bat main body to reduce the filling amount and fill the expanded methacrylic resin beads with an internal volume of approximately 100%. Since the foamed methacrylic resin beads are subjected to secondary foaming treatment to form a foam core material in a sealed state, the weight is reduced and a large constant pressure from the inside by the foam core material in a wide area with respect to the bat body Acts to form a large sweet spot area and to improve the shock absorption characteristics.

  Hereinafter, a baseball or softball bat 1 shown as an embodiment of the present invention will be described in detail with reference to the drawings. The bat 1 includes a bat body 2 made of a lightweight metal, for example, aluminum or an alloy thereof, a metal material made of titanium or an alloy thereof, or FRP, and a foaming property sealed in an internal space 2A of the bat body 2. It is comprised from the foaming core material 3 formed of the resin bead 15. The bat 1 uses, for example, an aluminum material as a material, and forms a cylindrical bat material as will be described in detail later, a spinning rolling process on the cylindrical material, and a swaging process The bat main body 2 having a predetermined shape is formed through the steps.

As shown in FIG. 1, the bat main body 2 includes a sweet spot portion 4 having a slightly thicker diameter and a substantially uniform shaft diameter and a predetermined length with the distal end closed, and a base end from the sweet spot portion 4. The taper portion 5 that is gradually reduced in diameter toward the head, the narrow grip portion 6 that has a predetermined axial diameter from the taper portion 5 and continues, and the end of the grip portion 6 around the circumference. It is comprised from the grip end part 7 formed by protrusion. The bat body 2 is provided with an opening 8 in the grip end portion 7, and an internal space 2 </ b> A that is sealed by fitting and fixing a plug member 9 formed of a nylon resin material into the opening 8. Composed.
The bat body 2 is formed in a cylindrical body having a substantially bottomed long axis, with the end portion of the sweet spot portion 4 closed and the opening 8 provided in the grip end portion 7. The bat body 2 is formed with a substantially uniform thickness as a whole, and an internal space 2A is formed that is filled with a foamed resin material that forms the foam core material 3 over its entire length. The bat body 2 is formed such that the foam core material 3 having a large thickness is formed in the internal space 2 </ b> A having a large inner diameter in the sweet spot portion 4, and the foam core material 3 is also formed in the grip portion 6 via the taper portion 5. To.

For the foamed core material 3, foamed methacrylic resin beads 15 that have been subjected to a predetermined foaming process, for example, a foaming process of about 20 times, as a foamed resin material are used. By the way, a methacrylic resin has a large foaming characteristic, hardness, or light weight as compared with an expandable vinylidene resin, an expandable polypropylene resin, or an expandable polystyrene resin. For example, methacrylic resin has a large foaming characteristic of about 1.8 times the hardness and about 0.7 times the weight in the same volume as compared with the expandable vinylidene resin. The foamed methacrylic resin beads 15 are made of methacrylic resin beads having such characteristics. The bat body 2 is filled in the internal space 2A from the opening 8 of the grip end portion 7 with an internal volume of approximately 100%.
As will be described in detail later, the foam core material 3 is obtained by subjecting the bat body 2 to a predetermined heat treatment in a state where the plug member 9 is fitted into the opening 8 and the internal space 2A is sealed, thereby expanding the foamed methacrylic resin beads. 15 is subjected to a secondary foaming treatment. The foamed core material 3 acts to increase the internal pressure of the internal space 2 </ b> A by further expanding the foamed methacrylic resin beads 15 from the state where the internal capacity is approximately 100% in the internal space 2 </ b> A of the bat body 2.

In the bat 1 configured as described above, as described above, the bat body 2 including the tapered portion 5 and the grip portion 6 is formed with a uniform thickness as a whole, thereby reducing weight and weight balance. Is optimized. In the bat 1, the expanded methacrylic resin beads 15 of about 20 times are used as the material of the foam core material 3, so that even if a larger filling space portion is formed inside the bat body 2, in other words, a large sweet spot portion. Even if it comprises 4, the weight increase is suppressed and the foam core material 3 with a large hardness is formed over the full length. In the bat 1, foaming is performed to increase the internal pressure of the bat body 2 by subjecting the bat body 2 to heat treatment in a state in which the internal space 2 </ b> A is sealed and secondary foaming of the foamed methacrylic resin beads 15 having high foaming characteristics. A core material 3 is formed.
In the bat 1, the repulsive force of the bat main body 2 is increased by generating a large internal pressure by the foamed core material 3. In the bat 1, the foamed methacrylic resin beads 15 are packed over the entire inner space 2 </ b> A of the bat body 2 to form the foamed core material 3, so that the portion close to the tip portion, the tapered portion 5, or the grip portion 6. The ball that hit the ball can produce the same hitting feeling and flying distance as the ball hit the sweet spot in the conventional bat.
That is, in the bat 1, the sweet spot portion 4 can be expanded by suppressing the increase in weight and forming the foam core material 3 in a large area of the bat body 2. In the bat 1, the foam core material 3 that applies a large internal pressure to the bat body 2 improves the shock absorption, thereby absorbing a large impact or vibration at the time of impact. Therefore, in the bat 1, the foam core material 3 has the same characteristics as the wooden bat, which reduces the burden on the user and reduces damage to the bat body 2 to improve durability. It is done. In the bat 1, for example, it is not necessary to fill the interior space of the bat body with a sound deadening material or the like like a conventional metal bat.

The bat 1 configured as described above includes a process of manufacturing the bat body 2 and a process of forming the foam core 3 in the internal space 2A of the bat body 2. As described above, the manufacturing process of the bat main body 2 includes a cylindrical material forming process, a spinning rolling process, and a swaging process using a metal material or FRP made of aluminum, its alloy, titanium, its alloy, or the like. Then, the bat body 2 is formed. The manufacturing process of the bat main body 2 forms the cylindrical material 10 shown in FIG. 2 by the cylindrical material forming process. The cylindrical material 10 has substantially the same diameter as the axial diameter of the sweet spot portion 4, and the entire thickness is formed to be approximately equal to the thickness of the bat body 2.
The manufacturing process of the bat body 2 is performed by subjecting the cylindrical material 10 to a rolling process using the spinning rolling device shown in FIG. The bat body material 11 shown in FIG. 4 having a reduced diameter to a predetermined shaft diameter is formed. As shown in FIG. 3, the spinning rolling apparatus is arranged at a position different from each other in the circumferential direction on the cored bar 12 of a predetermined shape that is inserted into the inner hole of the cylindrical material 10 and the outer peripheral part of the cylindrical material 10. A plurality of rolled rollers 13a to 13c are provided. The spinning rolling apparatus presses the rolling rollers 13a to 13c against the outer peripheral portion while rotating the cylindrical material 10, so that the corresponding portion H of the cylindrical material 10 and the grip portion 6 are rolled into a predetermined shape. Process.

The cored bar 12 is formed with an appropriate taper taper so that the material can be taken out after processing.
In the spinning rolling process, the corresponding portion H described above is rolled by pressing the rolling rollers 13a to 13c with a predetermined pressure and moving them in the axial direction while rotating the cylindrical material 10 at 300 rpm to 600 rpm. In the spinning rolling process, for example, by controlling the pressing operation and the moving operation of the rolling rollers 13a to 13c by a motion controller, the taper portion 5 and the grip portion 6 that are continuous from the sweet spot portion 4 to the cylindrical material 10 are supported. The part is efficiently and precisely formed into a predetermined shape. In the spinning rolling process, the material can be formed into a predetermined shape without damaging the material, so that the mechanical strength of the bat body 2 is improved.
By the way, in the spinning rolling process, it is possible to form the bat body material 11 having a predetermined shape in a state where the corresponding portions of the taper portion 5 and the grip portion 6 are held at a predetermined thickness, as shown in FIG. More specifically, the taper portion 5, the sweet spot portion 4 and the grip portion 6 of the bat main body material 11 are not yet formed in a final shape.

Therefore, in the manufacturing process of the bat main body 2, the sweet spot portion 4 and the grip portion 6 are interposed via the taper portion 5 by performing a cold swaging processing step that is conventionally performed on the bat main body material 11. The bat body 2 having a predetermined shape shown in FIG. In the manufacturing process of the bat main body 2, although details are omitted, a rounding process for closing the tip part and a process of forming the grip end part 7 at the end part of the grip part 6 are also performed in the subsequent process.
In the manufacturing process of the bat 1, a process of filling the internal space 2 </ b> A with the foamed methacrylic resin beads 15 in the bat body 2 manufactured through the above-described processes, and a process of fixing the plug member 9 to the opening 8. Then, the foamed core material 3 is formed through the secondary foaming process of the foamed methacrylic resin beads 15 to manufacture the bat 1. In the manufacturing process of the bat 1, in the filling process of the expanded methacrylic resin beads 15, the expanded methacrylic resin beads having the above-described excellent characteristics from the opening 8 of the grip end portion 7 with respect to the bat main body 2 as shown in FIG. 15 is filled in the internal space 2A. In the manufacturing process of the bat 1, since the methacrylic resin beads 15 are filled from the opening 8 on the grip end portion 7 side, the mechanical rigidity of the bat main body 2 is increased as compared with the structure of filling from the large diameter tip side. To be able to.
In the filling step of the expanded methacrylic resin beads 15, the expanded methacrylic resin beads 15, which have been increased by about 20 times by subjecting the expanded methacrylic resin bead powder to a foaming process in which steam and heat are applied in advance, overflow the opening 8. The inner space 2A is filled with approximately 100% of the volume so as to exit. The filling process of the expanded methacrylic resin beads 15 becomes considerably heavy when the expanded methacrylic resin beads 15 are filled in the bat main body 2 in an unexpanded state with a capacity of about 100%. By applying, the increase in weight is suppressed.

In the manufacturing process of the bat 1, when the foamed methacrylic resin beads 15 having a reduced expansion ratio are used, the weight of the bat main body 2 is increased even if it is lighter than other foamed resin materials. Will increase. Further, in the manufacturing process of the bat 1, when the expanded methacrylic resin beads 15 having a larger expansion ratio in order to suppress the filling amount are used, even if the expansion characteristic is large compared with other expanded resin materials, the secondary It is difficult to generate a sufficient internal pressure by performing a foaming process. Therefore, in the manufacturing process of the bat 1, expanded methacrylic resin bead powder expanded to about 10 times to about 30 times, preferably about 20 times is used.
In the manufacturing process of the bat 1, the internal space 2 </ b> A of the bat body 2 is made a sealed space by fitting the plug member 9 into the opening 8 and fixing it with an adhesive or the like. In the manufacturing process of the bat 1, a secondary foaming process in which the foamed methacrylic resin beads 15 are secondary foamed in this state is performed. The secondary foaming step is a step of heating the bat body 2 at 120 ° C. for about 30 minutes, for example, and further foams the expanded methacrylic resin beads 15 expanded about 20 times in the internal space 2A. The expanded methacrylic resin beads 15 are expanded by crushing each other space in the internal space 2 </ b> A, thereby increasing the volume and constituting the expanded core material 3 that applies a large internal pressure to the bat body 2. . In the manufacturing process of the bat 1, the bat 1 in which the foam core material 3 is formed in the internal space 2 </ b> A of the bat body 2 is manufactured through the secondary foaming process of the expanded methacrylic resin beads 15 through the above processes.
In the manufacturing process of the bat 1, finishing processing such as painting or engraving is performed before putting the beads, and after obtaining the above-described process, a non-slip vantage is wound around the outer periphery of the grip portion 6 and the bat 1 1 is completed.

It is sectional drawing of the bat shown as embodiment. It is sectional drawing of the cylindrical raw material used as the raw material of a bat main body. It is process explanatory drawing which performs a spinning rolling process to a cylindrical raw material with a spinning rolling apparatus. It is sectional drawing of the bat main body raw material which gave the spinning rolling process. It is sectional drawing of the bat main body formed by giving cold swaging processing to the bat main body raw material. It is sectional drawing of the bud main body which gave the bat main body material the rounding process and the process with an end. It is process explanatory drawing with which a bat main body is filled with an expanded methacrylic resin bead.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bat 2 Bat main body 2A Internal space 3 Foam core material 4 Sweet spot part 5 Taper part 6 Grip part 7 Grip end part 8 Opening part 9 Plug member 10 Cylindrical material 11 Bat main body material 12 Core metal 13 Rolling roller 15 Foamed methacrylic resin beads

Claims (3)

  Aluminum or its alloy, titanium or its alloy metal material or fiber reinforced plastic is used as the material, the tip is closed and the grip end is provided with an opening to form a cylindrical body with a substantially bottomed long axis. And a foamed core material formed of foamable resin beads filled in the internal space from the opening of the bat body, and the foamed core material is foamed with a predetermined foaming treatment. Using methacrylic resin beads, the bat body is filled with a content of about 100%, and the foamed methacrylic resin beads are subjected to secondary foaming by closing the opening and sealing the internal space. A bat characterized by being formed.   The tip part is closed using aluminum or its alloy, titanium or its metal material or fiber reinforced plastic as a raw material, and the entire grip end is formed into a cylindrical body with a bottomed long axis. A method for producing a bat comprising a bat body and a foam core material formed of foamable resin beads filled in the internal space of the bat body, and the foamed resin beads are subjected to a predetermined foaming treatment. Methacrylic resin beads are used, and the step of filling the foamed methacrylic resin beads into the internal space of the bat body from the opening on the grip part side with an inner volume of about 100% and the opening on the grip part side are plugged By inserting and fixing a member, a step of forming the internal space of the bat body into a sealed space portion, and adding to the bat body Method for producing a butt, characterized in that by applying the process and a step of the foamed methacryl resin beads is the secondary foaming in said interior space.   The manufacturing process of the bat main body includes a step of forming a cylindrical cylindrical material using the material, a core metal is inserted into an inner hole of the cylindrical material, and the position is different from each other in the circumferential direction. The corresponding region of the grip portion is made to have a predetermined thickness by performing a spinning rolling process in which the plurality of arranged rolling rollers are pressed against the outer peripheral portion and the respective rolling rollers are moved in the axial direction while rotating the cylindrical material. A bat having a predetermined shape in which a grip portion and a sweet spot portion are connected by a continuous surface via a taper portion by forming a bat body material and applying a cold swaging process to the bat body material. The bat manufacturing method according to claim 2, further comprising: forming a bat body having a predetermined shape having an opening in the grip portion.

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