JP2002052107A - Bat for baseball satisfying standard specification - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum baseball bat which has the ball repulsion characteristic nearly to that of a wooden bat and is therefore substantially almost the same in a bat velocity as that of the wooden bat with a similar weight, shape and size. SOLUTION: The bat has an outer shell 10 formed of aluminum and a packing material 30 packed into the shell at the point of a ball hitting region. The outer shell has the largest external diameter in the ball hitting region and is so set that the ratio of the largest external diameter to the thickness of the shell in the hitting region is 40:1 to 90:1. The packing material comes into contact with the annular inside surface of the shell in the hitting region, supports the same from the inner side and has partial density ranging from 10 to 30 lbs/cu.ft. (about 0.02 to 0.06 kg/cm3) and hardness from 25 to 65 with a Shore D tester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rigid shell tuber bat having an outer shell of metal or composite material,
In particular, it relates to aluminum baseball bats commonly used at colleges and low levels. Such bats typically have a metal shell formed of a resin composite, an alloy of aluminum or titanium, or other metal. Such bats are used in baseball and softball at virtually all levels that are not professional baseball levels. Here, the terms "aluminum" and "titanium" include the metal itself, mixtures of the metal, alloys of the metal, and formulated alloys for the manufacture of bat shells.

[0002]

BACKGROUND OF THE INVENTION Recently, National Collegi
ate Athetic Association
(NCAA) found that, for player safety reasons, the hitting speed of a hit ball with a non-wood bat was 34 inches (86.36 cm), a major baseball standard
That it must be less than the maximum average pop-out speed using a solid wooden bat. Indicated. Bats meeting such specifications are expected to reduce the occurrence of obstacles to players and reduce the danger in games. A typical 34 inch bat is about 10,5
00 to 12,000 oz. in ² (ounce x (inch) ² ) (about 1920 kg · cm ^{2 to} about 2194 k
g · cm ² ), so that a cylindrical hard shell bat can be used for 10,500 oz.
It is envisioned that it must have a moment of inertia less than or close to in ² . Test the moment of inertia to determine the weight of the bat in ounces and the balance point in inches and 6 inches (15.24 cm) from the base of the knob to swing like a pendulum
It is determined by pivoting away and measuring the average swing time over a period of not less than 10 cycles.

[0003] Cylindrical bats are known which are formed by a hardened outer shell and a reinforced or shock-absorbing inner layer which may have a solidified foam therein. For example, SI
MULATED WOOD COMPOSITE BA
Sound on March 7, 1995 under the name of LL BAT
US Patent 5,395,10 to r et al
The bat described in No. 8 has a composite shell reinforced with fiber that is filled with expandable urethane foam to provide compressive stress therebetween. Also, on November 15, 1994, Easton e
U.S. Pat. No. 5,364,095 to tal discloses a cylindrical metal ball bat reinforced internally with a fiber composite.

Also, US Pat. No. 5,114,144, issued to Baum on May 15, 1992, discloses an extruded aluminum coated with a layer of woven or woven cloth impregnated with a synthetic resin. Or a foam core (foam density of 5 to 15 1 bs / cu.ft. (About 0.01 to 0.03 kg / cm ³ )) and a resin coated wood veneer,
A composite baseball bat is disclosed that has an elongated plate or piece surface layer to form a wooden bat. Baum on October 17, 1995
U.S. Patent No. 5,458,330, issued to the date, discloses a composite bat having a wooden veneer surface and a hollow foam core. In addition, Baum in October 1995
U.S. Pat. No. 5,460,369, issued on May 24, discloses a composite bat having an intermediate composite layer bonded to a composite hollow core and a wooden veneer surface. The core may have flexible urethane foam, and a cavity may be present in the core at the impact area, wherein the cavity may be filled with a low density material. And the core is preferably
With a relatively high density near the end of the barrel, the density can be varied throughout the length of the bat.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ball resilience characteristic similar to the ball resilience characteristics of a wooden bat by emulating the longitudinal flexibility and cross-sectional rigidity characteristics of a wooden bat of similar size and shape. It is an object of the present invention to provide a double hardened shell baseball bat in which the speed of the bat swung is substantially the same as that experienced with a wooden bat of similar weight, shape and size.

[0006]

SUMMARY OF THE INVENTION The present invention provides: a) a ball having a maximum outer diameter in the hitting area and a ratio of the maximum outer diameter to the thickness of the shell wall in the hitting area of 40:
A cylindrical outer shell of 1 to 90: 1, b) contacting and supporting the annular inner surface of the shell from the inside in the hitting area, from 10 to 30 lbs. / C
u. ft. (About 0.02 to 0.06 kg / cm ³ )
And a filler having a hardness of 25 to 65 in a Shore D test apparatus. Furthermore, the present invention provides a)
An aluminum alloy shell having a maximum outer diameter to shell wall thickness ratio of 45: 1 to 75: 1 in the ball hitting area; b) contacting the inner annular surface of the shell in the hitting area with the inner face; From 10 to 30 lbs. / C
u. ft. (About 0.02 to 0.06 kg / cm ³ )
And a filler having a partial density in the range of 40 to 65 and a hardness of 40 to 65 on the Shore D test apparatus, having a longitudinal flexibility close to that of a wooden bat of the same geometric shape. Provides an aluminum shell ball bat.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS.
The baseball bat has a rigid outer shell 10 formed of a composite structure or metal or alloy, preferably aluminum. This outer shell has a handle 12
, A barrel (barrel) 14, and a tapered portion 16 connecting these handles and the barrel. A knob 20 closes the handle end of the bat, and a plug 22 is typically secured to the end of the bat tube, as is known. The ball hit area of the bat, that is, the hitting area, extends over substantially the entire length of the cylindrical portion 14 and extends to a part of the tapered portion of the bat.

The specifications of the bat of the present invention are deliberately designed to match or resemble the specifications of a typical wooden bat of similar weight and shape by imitating the cross-sectional rigidity and longitudinal flexibility of the wooden bat. Have been. Wood is very flexible to bending, thus reducing the effective leverage created by batters. At the same time, the high cross-sectional stiffness of the hard wooden bat, if any, causes a slight so-called "trampoline effect", which results in a higher hitting ball speed generated by a typical aluminum bat.

Metals, such as alloys of aluminum and titanium, are much more significant than wood if the metal shell bat is formed with approximately the same outside diameter, ie, geometry, as the correspondingly formed wooden bat. Due to its high modulus of elasticity, metal shell bats have a substantially higher longitudinal stiffness, when formed of an aluminum alloy, than 2.5 to 3.0 times that of wooden bats. are doing. In order to increase the longitudinal flexibility of a metal shell bat as much as a wooden bat, the shell wall thickness must be significantly reduced. When the shell wall thickness is reduced to increase the longitudinal flexibility to the desired degree, the bat diameter relative to the wall thickness is about 67: 1 for an aluminum shell bat. Was found by experiment. However, this presents another problem in that the walls are not thick enough to combat the tough game without increasing the permanent distortion due to the impact. Also, thinning rather than thickening the metal shell bat wall generally results in an undesirable high ball rebound due to the high flexibility of the bat wall, commonly referred to as the "trampoline effect". In comparison, wooden bats have a high cross-sectional rigidity (low trampoline effect) that withstands ball impacts well.

Known prior art composite bats having resilient walls as well as metal shell bats have a partially flexible outer wall of the bat shell so that they rebound in response to the impact of the struck ball, It has been deliberately designed to create a trampoline effect to provide thrust that increases the speed of the ball. It is an object of the present invention to control or reduce the speed of the ball struck to the extent that would be experienced with a wooden bat at best, so that the impact resistance in the striking area to substantially eliminate or reduce the trampoline effect Bats having a thin bat shell wall have been developed to increase longitudinal flexibility in combination with a semi-cured low density material that functions as filler 30. In a preferred embodiment, the semi-cured low-density material forming the filler 30 is a foam, especially a lightweight synthetic resin foam, ie, a microsphere.
Or a foam having a functional equivalent to that contained therein. However, it will be appreciated that those in the field can choose various other materials to achieve the same effect. Although not limited,
The filling material 30 is made of a lightweight material, packed hair (packed hair).
sphere) (eg, glass or plastic microshair or mixtures thereof),
Lightweight granules, such as plastic beads (eg, of propylene, polyethylene and nylon), shell flour, corn flour, sand and mixtures thereof; Bron thermoset or thermoplastic foams of (polyurethane, nylon, polythrene); It can be formed with these mixtures. This filler 30 may be formed by casting at a predetermined position in the shell or may be preformed and then inserted therein. A void at the end of the tube portion 14 extending about one inch (2.54 cm) from the plug 22 at the end of the tube may remain.

[0011] The shell is designed such that the bat has substantially the same flexible end to end from one end to the other as the correspondingly shaped wooden bat, and a geometric shape, such as K749. It is preferably formed of an aluminum alloy. Aluminum alloy tube 14
Is set to be a very thin wall in the hitting area (generally, a part of the cylindrical portion 14 and the tapered portion 16) as compared with the conventional aluminum bat. A typical conventional aluminum bat is 0.880 to 0.890.
It has an outer handle diameter of inches (about 2.24 to 2.26 cm) and a shell wall thickness of about 0.080 to 0.100 inches (about 0.203 to 0.254 cm). In the present invention where an aluminum alloy is used as the shell material, the thickness of the shell wall is 0.039.
To 0.055 inch (about 0.10 to 0.14c
m), preferably between 0.045 and 0.050 inch (about 0.11 to 0.13 cm). Also, if titanium is used as the shell material, the wall thickness must be further reduced to have the desired longitudinal flexibility, for example, about 0.030 inches (about 0.030 inches). 0.08 cm).

The ratio of the outer diameter of the cylindrical portion 14 to the thickness of the shell wall in the impact area is about 4 depending on the shell material used.
The ratio is 5: 1 to 75: 1, which is slightly larger for titanium. Bat shells formed of a composite such as resin reinforced with carbon or fiberglass strands are also contemplated in the present technique, but have not been manufactured and tested. In comparison, a typical conventional aluminum bat exhibits a wall to wall ratio of about 20 to 25: 1. The relatively thin-walled shell 10 has a semi-hardened (compared to conventional resilient fillers used to cushion impact) filler 30 in a preferred embodiment.
A hard shell bat with excellent longitudinal flexibility close to the operating characteristics of a similarly shaped wooden bat, formed of a synthetic resin foam substantially filling the interior of the bat shell 10 in the hitting area; Has become. The synthetic resin foam is a plastic, non-blown resin foam having mixed bubbles, such as by mixing the microshair with the resin component, rather than forming bubbles during solidification of the foam component.

As noted above, other materials may be used to form a relatively light, incompressible filler to provide an inward support for the thin walled butt shell 10. obtain. For example, it may include a gas or other blowing agent that blows the microshair into a thermoplastic or thermoset resin matrix, or may include shell powder, corn powder, sand, or glass or plastic microshair. Blow foams containing packed particulate material may be used. 10 to 35 lbs. /
cu. A filler having a density of about 0.02 to 0.07 kg / cm ³ and a hardness of 25 to 65 as measured by a Shaw D test apparatus is a thin-walled aluminum shell as described above. It has been found that it is necessary to properly form the support from the inside for the. At present, Applicants desire to use dicyclopentadiene (DCPD) resin, which is a thermoset resin foam with microshair mixed therein. Metal foam structures are also contemplated.

In order to achieve the objects of the present invention, a carefully controlled relationship between the strength and density of the foam filler 30 in the hit area and the wall thickness of the metal shell 10 must be maintained. In general, low packing densities can be used when the shell walls are relatively hot, without material impact on the weight of the bat. As the shell walls become thinner, denser fillers are desired to maintain proper weight and balance. Also, the filler 30 must be stiff to minimize radial displacement of the shell 10 during impact of the bat. As the size of the bat increases, a lighter filler 30 is required to keep the bat from becoming too heavy.

FIG. 3 shows two related curves, each showing the relationship between filler density and hardness versus shell wall thickness. One curve is 2x5 / 8 inch (about 6.68 c
m) for a bat having an outer diameter of 2, while the other curve is for a bat having an outer diameter of 2 x 1/2 inch (about 6.35 cm). The density curve is shown by the solid line,
The hardness curve is indicated by a broken line. The shell wall thickness in inches is shown on the vertical axis and the density is lb
s. / Cu. ft. Where hardness is expressed in Shore D units and these are shown on the horizontal axis. Typically,
The 2x5 / 8 inch metal shell bat is 0.04 inch so that the shell has adequate flexibility without being heavy.
30 to 0.55 inches (about 0.08 to 1.40
cm) thick shell walls. With future developments in Al or Ti strength, it may be possible to use metal shell walls thinner than those described here in the future. For aluminum shells using commonly available materials, the minimum wall thickness should not be less than 0.039 inches (about 0.1 cm). If a relatively strong metal such as titanium is used, 0.032 inches (about 0.08 inches)
cm) seems to be the minimum acceptable operable shell wall thickness to achieve wood-like flexibility. The final wall thickness can be adjusted as necessary to achieve a comparable dynamic compression response and well-tuned bending composition to the wood bat corresponding to the filler used.

10 lbs. / Cu. ft. (About 0.0
Low partial density such as 2 kg / cm ³ )
Light foam with nal density should be used for relatively thick butt shell walls, while 35 lbs. / Cu. ft. (About 0.07
Heavy foams with high partial densities, such as kg / cm ³ ), are required when the shell wall thickness is near the lower end of said tolerance range. About 0.050 Itin (about 0.13 cm) for relatively heavy aluminum shell butt
Thick shell wall is approximately 20 lbs. / Cu. ft.
It was found that only a filler density (about 0.04 kg / cm ³ ) was required, resulting in a limit combination that could withstand the impact. The filler hardness of about 40 in the Shore D test apparatus is:
The shell wall thickness is near the upper end of the range, for example, about 0.050 inch (about 0.13 c
m) proved to be suitable. However, if the shell wall thickness in the hit area decreases, a harder filler material is required. Generally, the hard filling material is
Due to the weight, holes 32 in the annular wall of the filler 30 can be formed to reduce the weight, as described below, without sacrificing the required strength. Similar curves are also shown in the diagram for a 2x1 / 2 inch aluminum shell batni which would have a corresponding shell wall thickness, foam density, and filler hardness.

The filler 30 can be introduced into the bat shell 10 in the hit area in various ways. These methods are, for example, pressing, transfer molding, injection molding or injection molding after the foam has not yet been solidified or fully cured in the form of a pre-molded foam core. Alternatively, the uncured resin component, the cured component, and the micro hair may be put together in the bat shell 10, and the resin foam may be cured at that location.
If a foam filler is used, preferably
The foam may be cured during the filling process or during curing to prevent voids from forming during normal use of the lovat between the interior surface of shell 10 and the interior of foam filler 30 or the foam itself. It has a shrinkage of less than 1%. For maximum durability, great care must be taken with each step of the bat making, e.g. pressing the filler into place, if the shrinkage of the foam exceeds the desired limits and minimizes or eliminates voids. Is particularly necessary. The bat constructed as described above is 34 inches (86.36c).
m) required for 10,500 oz. −i
n ² . Has a moment of inertia that substantially meets or exceeds the reference description of minimum moment of inertia.

Although tacky adhesives can be used,
There is essentially no need for a tacky adhesive between the metal shell 10 and a foam filler 30, such as a synthetic resin foam, and if the foam is injected or poured into the shell and cured there. Is not particularly necessary. Because
The adhesive causes deterioration of the upper part of the foam core,
This is because the resin foam typically expands during the curing process, causing significant compression interengagement between filler 30 and shell 10 without the use of additional adhesive. Further, a metal shell 10 made of aluminum is used.
During the manufacturing process, the foam may be heated to expand its nominal diameter and then cooled to shrink to the intended final diameter as the foam cures. As a result, Ciel 1
0 and a significant compressive stress occurs between the filler 30 and the filler 30 without using a separate tacky adhesive.
Can be held in place. The cured foam is characterized by almost no holes or gaps in the filler 30 and between the annular surface of the filler and the butt shell.

As the filler 30 becomes heavier, as the shell wall becomes thicker, as the bat becomes heavier, and as the bat wall becomes thinner, the proper bat weight, balance and support of the shell wall are obtained. The need to foam with higher density and stiffness increases to maintain Very thin metal shell walls require a denser and harder filler 30 because the compression and shear strength of the foam decreases as the density decreases. Also,
The foam must not interfere with the designed longitudinal flexibility of the shell that must be maintained.
This is because shell materials such as aluminum and titanium have a much higher composition and density than wood.

The longitudinal flexibility of the bat is determined independently of the flexibility of the handle, the tapered connection area and the barrel, so that the butt and one end of the wooden bat of the corresponding weight and geometry are determined. From the other end. Each test is determined by supporting the bat at two locations about 15 inches (about 38.1 cm) apart. Therefore, when testing the handle 12, one of the support positions is
Near the knob 20 and when testing the barrel, one support position is near one end of the bat barrel. And preferably, about 80 pounds (about 36.29
kg) of vertical load is applied midway between the two support positions, ie, 7.5 inches (about 19.05 cm) away from the support position, and the applied load is the same load applied to the wooden bat. The desired warpage is produced in a manner similar to that produced. Test results show that the desired warpage at the handle 12 must be in the range of 0.046 to 0.055 itin (about 0.12 to 0.14 cm).

Approximately 15 inches (about 38.1 cm) apart 2
The butt tube portion 14 supported at the two positions is similarly tested for longitudinal tube flexibility. And, preferably, a vertical load of about 80 pounds is applied to the tube portion 14 between the two support positions, ie, 7.5 inches (about 19.05 cm) away from the support position. Thus, the applied load causes the same desired bow as would be caused by the same load applied to the wooden bat. The results of this test indicate that the desired warpage in the barrel should be about 0.0046 inches (about 0.012 cm).

Approximately 15 inches (about 38.1 cm) apart
The bat is supported at one of the two positions, and the flexibility of the longitudinal taper is similarly tested. And, preferably,
A vertical load of about 80 pounds is intermediate between the two support positions, or 7.5 inches (about 1 inch) from the support position.
9.05 cm) applied to the taper at a distance so that the applied load produces the desired bow similar to that caused by the same load applied to the wooden bat. The results of this test indicate that the desired warpage at taper 16 should be about 0.029 inches (about 0.07 cm).

A section stiffness test was also performed to determine the amount of radial displacement of the cylindrical portion 14, ie, the shell wall, under a load applied in the lateral direction. In these tests, the cylinder was supported horizontally in a V-shaped block, and a load of 550 pounds was applied from above to the cylinder.
1 inch square (2.54c
m ² ) by adding to a square block.
Wooden bats are typically 0.020 inches (approx.
05 cm). A typical conventional aluminum bat is 0.032 inch (about 0.032 inch).
8 cm). The thin wall bat of the present invention exhibits a high cross-sectional displacement of 0.104 inches (about 0.26 cm) when not internally supported by the filler 30 and is filled with a predetermined synthetic resin foam. In this case, it shows 0.018 inches (0.05 cm), that is, almost the same sectional displacement as a wooden bat. Thus, a thin-walled bat with filler is described to perform substantially the same properties as a wooden bat of approximately the same geometry.

FIG. 4 shows a pre-cast or molded bat foam filler 3 having a hole 32 in the annular surface.
Indicates 0. The weight per volume of the foam in which the holes are formed in this way (as opposed to the same weight per volume of the foam in which the holes are not formed) is as follows.
0 to 30 lbs / cu. ft. (Partial density within the density range of about 0.02 to 0.06 kg / cm ³ ). The filler 30 in the embodiment shown in FIG. 4 is significantly heavier than the preferred density range and is conveniently formed by using a pre-cast foam.
Foams having a density within the preferred density range are difficult to work because they can be cast raw and bare. To this end, the perforations in the annular surface of the foam are lightened without sacrificing the required support strength. As a result, the partial density of the filler 30 is reduced to a preferred range. Foam filler 30 in which holes are formed as shown in FIG.
Can be formed by various methods, such as by forming holes in a pre-formed mold or cast filler, or by using removable pins in the casting mold.

Fillers 30 that have been satisfactorily tested in rigorous tests are 10 to 30 lbs. / Cu. ft.
(About 0.02 to 0.06 kg / cm ³ ) within the preferred range of 22.5 lbs. / Cu. ft. (About 0.05 kg / cm ³ )
Approximately 41 lbs. With a suitable number of holes in a 15/64 inch annular surface. / Cu. ft. (About 0.08 kg / cm
³ ) Pourable D having a density of
Formed by CPD resin foam. 33 lbs. With 13/64 inch holes in the annular surface to reduce the partial density to the desired range. / Cu. ft. (About 0.07k
g / cm ³ ) of injectable foam were satisfactorily tested. The test method involved hitting 20 baseball balls at a speed of 136 mph (about 218.87 km / hr) on the same spot on the barrel of the bat.
Also, a similar test of the butt taper would result in 100 mph (approximately 160.
It was done by hitting 100 baseball balls at a speed of 93 km / h).

Preferably, the holes or holes 32 are drilled or drilled radially in the annular surface of the filler material 30, but this is not essential. The holes 32 may be blind holes approximately 1 inch (2.54 cm) deep or blind holes through the filler 30. A slightly higher rebound speed of the ball from the bat, if holes are used,
Can be expected. The pattern and spacing of the holes 32 in the annular surface of the filler material 30 is not considered essential, but may be regular, such as rows extending longitudinally at equal intervals in the circumferential direction or circles at equal intervals in the longitudinal direction. It is preferred to be formed in a simple pattern. The number and spacing of the holes 32 are
However, the indentation must be selected to safely support the thin-walled metal or alloy shell 10 and to avoid fatigue collapse under severe or normal conditions of use. If a circular hole 32 is used, the minimum distance between the centers of the holes should preferably not be less than about twice the diameter of the hole.

It is, of course, within the scope of the present invention to use holes other than circular holes and / or to use a mixture of holes of different sizes or shapes. It is believed that using more small holes is a more durable filler than using fewer large holes.

Those skilled in the art will recognize that various further modifications of the present invention can be made from the above embodiments, and that the scope of protection is defined only by the claims.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a bat according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the bat shown in FIG.

FIG. 3 is a diagram showing the relationship between various bat parameters, including the outer diameter of the hitting area, shell wall thickness, foam filler density, and Shore D hardness.

FIG. 4 is a perspective view of a perforated foam bat filler.

[Explanation of symbols]

10 outer shell, 12 handle, 14 cylinder (barrel), 20 knob, 30 filler

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Dewey Chowbin 7855, Haskell Avenue, Van Neuss, California 91406, USA

Claims (25)

[Claims] 1. a) having a maximum outer diameter in the ball hitting area;
A cylindrical outer shell having a maximum outer diameter to shell wall thickness ratio of 40: 1 to 90: 1 in the hitting area; and b) contacting the shell inner annular surface in the hitting area. This was supported from the inside and 10 to 30 lbs. / C
u. ft. (About 0.02 to 0.06 kg / cm ³ )
A ball bat with standardized specifications, comprising a filler having a partial density in the range of 25 and a hardness of 25 to 65 in a Shore D test apparatus. 2. The ball bat according to claim 1, wherein the filler is a foam material. 3. The ball bat of claim 2, wherein said foam material has a shrinkage during solidification of no greater than 1.0%. 4. The ball bat according to claim 3, wherein said foam material is a thermosetting resin having microbubbles mixed therein and a Shore D hardness in a range of 40 to 65. 5. The ball bat according to claim 4, wherein said foam material is a dicyclopentadiene (DCPD) resin. 6. The shell, wherein the shell is formed of aluminum and the ratio of the maximum outer diameter to the wall thickness of the shell in the hit area is 45: 1 to 75: 1.
2. The ball bat of claim 1 wherein said shell has a wall thickness between 0.039 and 0.055 inches in the hitting area. 7. The filler material is a foam material compressed and constrained within the shell, characterized by the absence of an adhesive between the foam material and the shell. 6 ball bat. 8. The impact area has a size of about 2 × 5/8 (about 6.6).
8 cm), and the partial density of the foam material is:
Approximately 25 pounds / cubic foot (approximately 0.05 kg / c
m ³⁾ and is, Shiyoa D hardness of the foam, the ball bat of claim 7 is about 55. 9. The filler is formed of an injectable material having a density greater than the partial density range, has a plurality of holes in an annular surface, and the filler further comprises: The ball bat of claim 1, wherein the ball bat is in contact with the bat shell in the hitting area. 10. The ball bat according to claim 9, wherein said holes are oriented radially. 11. The ball bat of claim 9, wherein said filler is a thermosetting resin having microbubbles mixed therein and a Shore D hardness in the range of 40 to 65. 12. The ball bat according to claim 11, wherein the foam material is dicyclopentadiene (DCPD) resin. 13. The shell is made of aluminum, and the ratio of the maximum outer diameter to the wall thickness of the shell in the hit area is 45: 1 to 75: 1, and Shells are 0.039 to 0.055 inches (about 0.10 to 0.14 cm) in the impact area
The ball bat of claim 9 having a wall thickness of: 14. The apparatus according to claim 1, wherein the hit area is about 2 × 5/8 (about 6.
68 cm) and the partial density of the foam material is about 25 pounds / cubic foot (about 0.05 kg / c
m ³⁾ and is, Shiyoa D hardness of the foam, the ball bat of claim 13 is about 55. 15. An aluminum alloy shell having a maximum outer diameter to shell wall thickness ratio of 45: 1 to 75: 1 in the ball hitting area; and b) an annular inner surface of said shell in said hitting area. And supports it from the inside, from 10 to 30 lbs. / C
u. ft. (About 0.02 to 0.06 kg / cm ³ )
And a filler having a partial density in the range of 40 to 65 and a hardness of 40 to 65 in the Shore D test apparatus, having a longitudinal flexibility close to that of a wooden bat of the same geometric shape. Aluminum shell ball bat. 16. The filling material is formed of an injectable material and has a plurality of holes in an annular surface, and the filling material is in contact with the bat shell in the hitting area. Item 15. A ball bat according to item 15. 17. The ball bat of claim 16, wherein said holes are woven in a radial direction and said injectable material has a density greater than said partial density range. 18. The ball bat of claim 16, wherein said material is a synthetic resin foam. 19. The shell of claim 19 wherein the hitting area is 0.039.
To 0.050 inch (about 0.10 to 0.13c
17. The ball bat of claim 16, having a wall thickness of m). 20. About 2 × 5/8 (about 6.
68 cm) and the partial density of the foam is:
Approximately 25 pounds / cubic foot (approximately 0.05 kg / c
m ³ ), and the foam has a Shore D hardness of about 5
20. The ball bat of claim 19, wherein the number is 5. 21. The ball bat according to claim 20, wherein the foam is a thermosetting resin having microbubbles mixed therein. 22. The ball bat of claim 21, wherein said foam is dicyclopentadiene (DCPD) resin. 23. The ball bat of claim 15, wherein said foam is constrained in a compressed condition within said shell. 24. The ball bat of claim 23, wherein said foam has a shrinkage during solidification of no greater than 1.0%. 25. The ball bat of claim 23, wherein the ball bat is characterized by the absence of an adhesive between the foam and the shell.