Practice baseball bat

Abstract

To provide a practice baseball bat that can realize accurate swings by improving bat control, reduce fatigue during long practice sessions, ensure versatility for both right-handed and left-handed batters, and ensure safety by improving grip strength. [Solution] The practice baseball bat 1 of the present disclosure has a bat body 10 and a grip portion 15 disposed on the base end 11 side of the bat body 10. A groove is formed on the surface of the grip portion 15, wrapping around the axis of the grip portion 15. The groove is composed of a plurality of grooves or a spiral groove 21.

Description

[Technical Field]

[0001] The present invention relates to a practice baseball bat. [Background technology]

[0002] In recent years, the technological development of baseball bats has made remarkable progress. For example, a practice baseball bat is known that has a predetermined length, a front end in the axial direction of which is formed as a handle portion that can be gripped by a user, and a rear end in the axial direction of which is formed as a bat head (see, for example, Patent Document 1).

[0003] This bat has a composite shaft section between the handle and the bat head end, with the composite shaft section having a bat main axis that is coaxial with the handle and the bat head end. An elastic annular body is annularly attached to the periphery of the composite shaft section, and the annular body is integrally connected to the composite shaft section. Furthermore, a sleeve made by braiding or weaving composite fiber bundles arranged at a predetermined angle into a tubular shape is annularly attached to cover the elastic annular body, and the sleeve forms a mesh-like resilient bridge around the outer periphery of the bat. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-196378 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional baseball bats, including the practice bat described in Patent Document 1, still have significant technical issues. In particular, problems stemming from the structure of the grip are prominent, which can be considered a serious technical issue for practice bats.

[0006] For example, because the grip of a conventional bat is based on a simple cylindrical shape, it is difficult to provide an optimal grip feel for both right-handed and left-handed batters. This problem is a major obstacle, especially for beginners and players in the training stage, preventing them from achieving stable bat control. Furthermore, it is difficult to obtain an appropriate grip feel depending on the batter's experience level and physique, hindering effective practice.

[0007] Furthermore, conventional grip structures do not have fully optimized surface treatments, making it difficult to provide optimal grip comfort depending on the batter's hand position and grip style. As a result, hand fatigue is significant during long practice sessions, making it difficult to continue practicing efficiently. It is also difficult to ensure sufficient grip strength both when used with bare hands and when wearing a glove. Thus, it can be said that conventional practice baseball bats have room for improvement in the grip area.

[0008] Furthermore, there is room for improvement in the selection of materials for the grip, and the current situation does not effectively reduce hand fatigue. These issues have a significant impact on batters' performance and hinder the improvement of their skills, especially during practice.

[0009] This invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide a practice baseball bat that can achieve accurate swings by improving bat control, reduce fatigue during long practice sessions, ensure versatility for both right-handed and left-handed batters, and ensure safety by improving grip strength. [Means for solving the problem]

[0010] The above-mentioned object of the present invention is achieved by the following configuration. [1] The bat body, a grip portion disposed on the base end side of the bat body, A groove is formed on the surface of the grip portion so as to wrap around the axis of the grip portion, The groove is composed of a plurality of grooves or a spiral groove. Practice baseball bat. [2] the groove is a double spiral groove, The double spiral groove is composed of a pair of spiral grooves that wind in opposite directions. [1] A practice baseball bat as described in [1]. [3] The plurality of grooves or the spiral groove are provided so that the depth thereof varies stepwise along the longitudinal direction of the grip portion. [1] A practice baseball bat as described in [1]. [4] The plurality of grooves or the spiral groove are provided at a pitch different from that at the center portion and at the end portions along the longitudinal direction of the grip portion. [1] A practice baseball bat as described in [1]. [5] A synthetic resin material is disposed at least at the bottom of the groove. [1] A practice baseball bat as described in [1]. [6] The cross-sectional shape of the groove is formed into a trapezoidal or arc shape whose width gradually decreases from the opening to the bottom of the groove. [1] A practice baseball bat as described in [1].

[0011] It is recommended to use the configuration described in [1] above. In this case, the grooves wound around the surface of the grip increase the contact area between the batter's hand and the bat, resulting in a more secure grip. This groove structure ensures an effective grip both when using the bat with bare hands and when wearing a glove. Furthermore, the spiral grooves provide an optimal grip feel for both right-handed and left-handed batters, achieving an appropriate grip that accommodates differences in batter experience level and physique, a challenge faced with conventional technology. This results in stable bat control and promotes the acquisition of an accurate swing. Furthermore, this groove structure reduces hand fatigue during long practice sessions, allowing for more efficient and continuous practice. It is recommended to use the configuration described above in [2]. In this case, a pair of spiral grooves wound in opposite directions provides an optimal grip for both right-handed and left-handed batters. Furthermore, this structure effectively suppresses bat wobble, enabling stable bat control. The double spiral groove structure also increases the contact area between the batter's hand and the bat, providing a more secure grip. Furthermore, an effective grip is ensured both when using the bat with bare hands and when wearing a glove, reducing hand fatigue during long practice sessions. It is recommended to use the configuration described above in [3]. In this case, the gradual change in depth evenly distributes pressure when gripping the bat, reducing discomfort and stress when gripping and helping to prevent hand fatigue during long periods of practice. The gradual change in groove depth also provides a natural guide for the grip, facilitating a more stable grip. This makes it easier for batters to grip the bat in the same position and form every time, improving the reproducibility of their swing. Furthermore, the gradual design with grooves of varying depths prevents the batter's grip force and pressure from concentrating in a specific area, reducing muscle fatigue in the hands and forearms during long periods of repetitive practice and reducing the risk of form problems and injury due to fatigue. It is recommended to use the configuration described above in [4]. In this case, the center of the grip is wrapped around the entire palm, while the edges are supported by the fingertips. This design optimizes friction and fit in each area by using a wider pitch in the center and a finer pitch at the edges. This design emphasizes ease of grip and stability in the center, while reducing fingertip slippage at the edges, supporting delicate control. As a result, grip slippage during a swing is suppressed, reducing bat trajectory deviation and improving accurate ball control and power transfer efficiency. Furthermore, the different pitches provide visual and tactile guidance, making it easy for even beginners to recognize the correct grip position, and the grip is adaptable to a variety of hand sizes and grip styles. It is recommended to use the configuration described above in [5]. In this case, the synthetic resin material has moderate elasticity and friction, which reduces the impact when gripping the bat and reduces strain on the palm and fingertips. It also ensures an effective grip, effectively reducing hand fatigue during long practice sessions. Furthermore, the properties of the synthetic resin material prevent slippage caused by moisture such as sweat or rain, creating a safer practice environment. It is recommended to use the configuration described above in [6]. In this case, the contact area between the batter's hand and the bat is optimized, effectively improving grip. In particular, the tapered width structure evenly distributes pressure on the hand and prevents excessive strain on any particular area. Furthermore, the trapezoidal or arc-shaped cross-section allows the fingers to naturally fit into the grooves when using the bat with bare hands or wearing a glove, providing a stable grip. Furthermore, this cross-sectional shape effectively wicks away moisture, such as sweat and rain, creating a non-slip structure. As a result, it becomes possible to maintain stable bat control even during long periods of practice, promoting the acquisition of accurate swing movements. [Effects of the Invention]

[0012] This invention makes it possible to achieve accurate swings by improving bat control, reduce fatigue during long practice sessions, ensure versatility for both right-handed and left-handed batters, and ensure safety by improving grip strength.

[0013] The present invention has been briefly described above. The details of the present invention will become clearer by reading the following detailed description of the invention (hereinafter referred to as "embodiments") with reference to the accompanying drawings. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of the appearance of a practice baseball bat according to a first embodiment. [Figure 2] Schematic diagram showing an example of the structure around the grip shown in Figure 1 [Figure 3]FIG. 3 is a cross-sectional view of a main part illustrating an example of the configuration of the spiral groove shown in FIG. 2. [Figure 4] FIG. 10 is an enlarged view of a main part illustrating an example of the structure of a double spiral groove according to a first modified example of the first embodiment. [Figure 5] FIG. 10 is an enlarged view of a main part illustrating an example of the configuration of a plurality of endless annular grooves around a grip portion according to a second embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One or more embodiments specifically disclosing a practice baseball bat according to the present invention will be described in detail below with appropriate reference to the accompanying drawings.

[0016] However, more detailed descriptions than necessary may be omitted. For example, detailed descriptions of already well-known matters or redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Furthermore, each of the accompanying drawings should be viewed according to the direction of the reference numerals.

[0017] Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0018] <Terminology> The terms "comprising" or "characterized by," which are synonymous with "comprising" and "containing," are intended to be interpreted in an inclusive or open-ended sense and do not exclude additional, unrecited elements or method steps. "Comprising" is a term of art used in claim language, meaning that the named claim elements are required, but that other claim elements may be added to form further structure within the scope of the claim. The terms "comprising" and "having" are similarly intended to be non-exclusive, meaning that there may be additional elements other than the recited elements.

[0019] Also, as used herein, the phrase "consisting of" excludes any element, step, or ingredient not specified in the claim. When the phrase "consisting of (or variations thereof)" appears in a section of the body of a claim rather than immediately following the preamble, it limits only the elements set forth in that section and does not exclude other elements from the claim as a whole. As used herein, the phrase "consisting essentially of" limits the scope of a claim to those elements or method steps specified in addition to those that do not materially affect the main and novel feature(s) of the claimed subject matter.

[0020] With respect to the terms "comprising," "consisting of," and "consisting essentially of," when one of these three terms is used herein, the presently disclosed and claimed subject matter may also include the use of either of the other two terms. Thus, in some embodiments not expressly recited otherwise, any instance of "comprising" may be replaced by "consisting of" or "consisting essentially of."

[0021] The term "process" or "step" may be used explicitly or implicitly in connection with process or method features, but no order or sequence is limited among such explicit processes or steps or among implicit processes or steps unless the order or sequence is stated.

[0022] First Embodiment A first embodiment of a practice baseball bat 1 according to the present invention will be described with reference to FIGS. 1 to 3. FIG.

[0023] [Basic structure of practice baseball bats]

[0024] An example of the basic configuration of a practice baseball bat 1 according to this embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram illustrating an example of the appearance of a practice baseball bat 1 according to this embodiment.

[0025] As shown in FIGS. 1 to 3, practice baseball bat 1 of this embodiment includes bat body 10 and grip portion 15.

[0026] Bat body 10 is the part used to directly hit a baseball, and is formed long and generally cylindrical or shaped like a bat. Grip portion 15 is integrally connected to one longitudinal end (base end 11) of bat body 10.

[0027] Bat body 10 is formed integrally with the grip from wood, but is not limited to this; various composite materials such as aluminum alloy, wood, and carbon fiber reinforced plastic may also be used as appropriate. The portion of the outer surface of bat body 10 other than grip portion 15 is set as the hitting area where the ball is actually hit. In this embodiment, the overall length, diameter, mass, etc. of bat body 10 are selected as appropriate depending on the user's physique and the purpose of practice.

[0028] Grip portion 15 is integrally formed at base end 11 in the longitudinal direction of bat body 10 and is the portion that the user grips with his or her hand. Grip portion 15 is formed in a generally cylindrical shape extending along the axial direction of bat body 10, and is generally thinner and shorter than the hitting portion, with a predetermined length. Grip portion 15 is made of the same material as bat body 10, but its surface may be coated with a synthetic resin or tape specifically for grips (see below for details).

[0029] In this embodiment, one spiral groove 21 is formed on the surface of the grip portion 15.

[0030] [About the spiral groove structure] An example of the configuration of one spiral groove 21 formed on the surface of the grip portion 15 will be described with reference to FIGS. FIG. 2 is a schematic diagram showing an example of the structure around the grip portion 15 shown in FIG. FIG. 3 is a cross-sectional view of a main part illustrating an example of the configuration of the spiral groove 21 shown in FIG.

[0031] As shown in FIGS. 2 and 3, in this embodiment, one spiral groove 21 is formed on the surface of the grip portion 15.

[0032] This spiral groove 21 has a structure that winds continuously from base end 16 to tip end 17 of grip portion 15. Spiral groove 21 winds in either a right-handed or left-handed direction and is formed approximately uniformly throughout grip portion 15. This single spiral groove 21 acts as a guide for the user's fingers when gripping the bat naturally, and can effectively prevent slippage, particularly in the rotational direction.

[0033] Furthermore, the spiral grooves 21 of this embodiment are provided with a depth and pitch that change stepwise along the longitudinal direction of the grip portion 15. For example, by providing deeper grooves in the area where the palm of the hand contacts and shallower grooves in the area where the fingertips contact, pressure distribution becomes even, making it possible to effectively reduce fatigue and discomfort during long periods of repetitive practice. Furthermore, by adopting a wider pitch on the palm side and a narrower pitch on both ends of the fingertips and little finger side, the pitch naturally corresponds to the spacing of the fingers when gripping, achieving a more secure grip.

[0034] Furthermore, a synthetic resin material RM is applied (one example of "disposed") to at least the bottom portion BT of the spiral groove 21. This synthetic resin material RM has appropriate elasticity and frictional force, and provides shock absorption and anti-slip functions when gripping, as well as preventing slipping due to sweat, rain, etc.

[0035] The cross-sectional shape of the spiral groove 21 is designed to be trapezoidal or arc-shaped, with the width gradually decreasing from the opening OP to the bottom BT. This structure makes it easier for the fingers to fit naturally into the groove, contributing to the dispersion of pressure and the efficient drainage of moisture.

[0036] That is, according to practice baseball bat 1 of this embodiment, a single spiral groove 21 is formed on the surface of grip portion 15 connected to one end of bat body 10. The depth and pitch of the groove change stepwise in the longitudinal direction, and synthetic resin material RM is disposed on bottom portion BT, giving the bat a trapezoidal or arc-shaped cross section. This results in practice baseball bat 1 that provides excellent grip, comfort, and safety for a variety of users.

[0037] [Features and advantages of this embodiment] [1] As described above, practice baseball bat 1 of this embodiment has bat body 10 and grip portion 15 disposed on the base end side of bat body 10. A groove is formed on the surface of grip portion 15, winding around the axis of grip portion 15. The groove is composed of multiple grooves or a spiral groove.

[0038] The grooves wound around the surface of the grip portion 15 increase the contact area between the batter's hand and the bat, resulting in a more secure grip. This groove structure ensures an effective grip both when using the bat with bare hands and when wearing a glove. Furthermore, the spiral grooves provide an optimal grip feel for both right-handed and left-handed batters, achieving an appropriate grip that accommodates differences in batter experience level and physique, a challenge faced with conventional technology. This results in stable bat control and promotes the acquisition of an accurate swing. Furthermore, this groove structure reduces hand fatigue during long practice sessions, allowing for more efficient and continuous practice.

[0039] [3] Furthermore, according to practice baseball bat 1 of the present embodiment, spiral groove 21 (one example of "multiple grooves or spiral grooves") is provided with a depth that varies stepwise along the longitudinal direction of grip portion 15.

[0040] This gradual change in depth evens out the pressure distribution when gripping the bat, reducing discomfort and stress when gripping and helping to prevent hand fatigue during long periods of practice. The gradual change in groove depth also allows the grip portion 15 to provide a natural guide for the fingers, facilitating a more stable grip. This makes it easier for the batter to grip the bat in the same position and with the same form every time, improving the reproducibility of the swing motion. Furthermore, the gradual design with grooves of varying depths prevents the batter's grip force and pressure from concentrating in a specific area, reducing muscle fatigue in the hands and forearms during long periods of repetitive practice and reducing the risk of form problems and injury due to fatigue.

[0041] [4] Furthermore, according to the practice baseball bat 1 of this embodiment, the spiral grooves 21 (an example of "multiple grooves or spiral grooves") are arranged along the longitudinal direction of the grip portion 15 at a different pitch in the central portion than in the end portions.

[0042] To accommodate this, the center of the grip is wrapped around the entire palm, while the edges are supported by the fingertips. The design optimizes friction and fit in each area by incorporating a wider pitch in the center and a finer pitch at the edges. This design emphasizes ease of grip and stability in the center, while the edges reduce fingertip slippage, supporting delicate control. This results in less grip slippage during the swing, reducing bat trajectory deviation and improving accurate ball control and power transfer efficiency. The different pitches also provide visual and tactile guidance, making it easy for even beginners to recognize the correct grip position, and the grip is adaptable to a variety of hand sizes and grip styles.

[0043] [5] Furthermore, according to practice baseball bat 1 of the present embodiment, synthetic resin material RM is disposed at least on bottom portion BT of spiral groove 21 (an example of a "groove").

[0044] Because the synthetic resin material RM has just the right amount of elasticity and friction, it absorbs the impact of gripping the bat and reduces strain on the palm and fingertips. It also ensures an effective grip, effectively reducing hand fatigue during long periods of practice. Furthermore, the properties of the synthetic resin material RM prevent slipping caused by moisture such as sweat or rain, creating a safer practice environment.

[0045] [6] Furthermore, according to the practice baseball bat 1 of this embodiment, the cross-sectional shape of the spiral groove 21 (an example of a "groove") is formed into a trapezoid or arc shape whose width gradually decreases from the opening OP of the groove toward the bottom BT.

[0046] This optimizes the contact area between the batter's hand and the bat, effectively improving grip. In particular, the tapered width evenly distributes pressure on the hand, preventing excessive strain on any particular area. The trapezoidal or arc-shaped cross-section allows the fingers to naturally fit into the grooves when using the bat with bare hands or wearing a glove, providing a stable grip. Furthermore, this cross-sectional shape effectively wicks away moisture, such as sweat and rain, creating a non-slip design. As a result, players can maintain stable bat control even during long practice sessions, promoting the development of accurate swing movements.

[0047] [Regarding one or more modified examples of this embodiment] One or more modifications of this embodiment will be described. Note that components identical or equivalent to those in the first embodiment described above may be denoted by the same or equivalent reference numerals in the drawings and description, and their description may be omitted or simplified. Furthermore, with regard to the technical content described in the claims of this utility model registration, it is not intended that the subject matter be limited in any way to one or more of these modifications.

[0048] (First Modification) A first modified example of this embodiment will be described with reference to FIG.

[0049] The configuration of the groove (double spiral groove 22) formed in the grip portion 15 in this modified example will be described with reference to FIG. FIG. 4 is an enlarged view of a main part for explaining an example of the structure of the double spiral groove 22 according to the first modified example of this embodiment.

[0050] As shown in Figure 4, in this modification, a pair of double spiral grooves 22 that wind in opposite directions are formed on the outer peripheral surface of the grip portion 15. The double spiral grooves 22 wind along the right-handed and left-handed thread directions, respectively, and are formed continuously throughout the entire grip portion 15. This provides a natural and stable gripping feel for both right-handed and left-handed batters, and also improves the fit of the fingers when gripping, the anti-slip effect, and the effect of suppressing bat wobble.

[0051] [2] According to practice baseball bat 1 of this modified example, the grooves are double spiral grooves. The double spiral groove is composed of a pair of spiral grooves that wind in opposite directions.

[0052] In this case, a pair of spiral grooves wound in opposite directions provides an optimal grip for both right-handed and left-handed batters. Furthermore, this structure effectively suppresses bat wobble, enabling stable bat control. The double spiral groove structure also increases the contact area between the batter's hand and the bat, providing a more secure grip. Furthermore, an effective grip is ensured both when using the bat with bare hands and when wearing a glove, reducing hand fatigue during long practice sessions.

[0053] <Second embodiment> A practice baseball bat 1 according to a second embodiment of the present invention will be described with reference to FIG. In addition, components that are the same as or equivalent to those in the first embodiment described above may be denoted by the same or equivalent reference numerals in the drawings, and their description may be omitted or simplified.

[0054] [Regarding the configuration of the multiple grooves in the grip portion 15] An example of the configuration of the plurality of grooves (endless annular groove 23) formed in the grip portion 15 according to this embodiment will be described with reference to FIG. FIG. 5 is an enlarged view of a main part illustrating an example of the configuration of the endless annular grooves 23 around the grip portion 15. As shown in FIG.

[0055] 5, in this embodiment, a plurality of endless annular grooves 23 are formed on the outer peripheral surface of grip portion 15, spaced apart at approximately equal intervals along the longitudinal direction of bat body 10. Each of the plurality of grooves is formed in a continuous (loop) shape around the circumference of the grip.

[0056] The endless annular grooves 23 are appropriately set according to the size of the user's hand and the gripping style. As in the first embodiment, the depth and pitch of each groove changes stepwise in the longitudinal direction. Similarly, a synthetic resin material RM is applied to each bottom BT of the groove. Furthermore, each cross-sectional shape may be formed into a trapezoid (or arc shape) whose width gradually decreases from the opening OP toward the bottom BT.

[0057] That is, in practice baseball bat 1 of this embodiment, instead of spiral groove 21 of the first embodiment, a plurality of endless annular grooves 23 spaced at approximately equal intervals on the surface of grip portion 15 are employed. In this case as well, it is possible to achieve stable gripping, excellent grip feeling, fatigue reduction, and slip resistance. The other configurations and their effects are the same as those of the first embodiment.

[0058] <Conclusion> Although one or more specific embodiments have been described above, the present invention is not limited to these embodiments, and modifications and improvements can be made as appropriate.

[0059] In other words, it is clear that a person skilled in the art can conceive of various modifications, alterations, substitutions, additions, deletions, and equivalents within the scope of the claims of the utility model registration, and it is understood that these also naturally fall within the technical scope of the present disclosure. Furthermore, the components in the above-described embodiments may be combined in any manner as long as they do not deviate from the spirit of the invention.

[0060] <Additional Notes> Furthermore, the features of the practice baseball bat (1) according to one or more embodiments described above will be briefly summarized and listed below in [1] to [6].

[0061] [1] The bat body, a grip portion disposed on the base end side of the bat body, A groove is formed on the surface of the grip portion so as to wrap around the axis of the grip portion, The groove is composed of a plurality of grooves or a spiral groove. Practice baseball bat. [2] the groove is a double spiral groove, The double spiral groove is composed of a pair of spiral grooves that wind in opposite directions. [1] A practice baseball bat as described in [1]. [3] The plurality of grooves or the spiral groove are provided so that the depth thereof varies stepwise along the longitudinal direction of the grip portion. [1] A practice baseball bat as described in [1]. [4] The plurality of grooves or the spiral groove are provided at a pitch different from that at the center portion and at the end portions along the longitudinal direction of the grip portion. [1] A practice baseball bat as described in [1]. [5] A synthetic resin material is disposed at least at the bottom of the groove. [1] A practice baseball bat as described in [1]. [6] The cross-sectional shape of the groove is formed into a trapezoidal or arc shape whose width gradually decreases from the opening to the bottom of the groove. [1] A practice baseball bat as described in [1]. [Industrial Applicability]

[0062] This invention is useful as a practice baseball bat that can achieve accurate swings by improving bat control, reduce fatigue during long practice sessions, ensure versatility for both right-handed and left-handed batters, and ensure safety by improving grip strength. [Explanation of symbols]

[0063] 1: Practice baseball bat 10: Bat body 11: Proximal end 12:Tip 15: Grip section 16: Proximal end 17:Tip 21 :Spiral groove 22:Double helical groove 23: Endless annular groove BT: Bottom OP: Opening RM: Synthetic resin material

Claims

1. The bat body, a grip portion disposed on the base end side of the bat body, A groove is formed on the surface of the grip portion so as to wrap around the axis of the grip portion, The groove is composed of a plurality of grooves or a spiral groove. Practice baseball bat.

2. the groove is a double spiral groove, The double spiral groove is composed of a pair of spiral grooves that wind in opposite directions.

2. The practice baseball bat of claim 1.

3. The plurality of grooves or the spiral groove are provided so that the depth thereof varies stepwise along the longitudinal direction of the grip portion.

2. The practice baseball bat of claim 1.

4. The plurality of grooves or the spiral groove are provided at a pitch different from that at the center portion and at the end portions along the longitudinal direction of the grip portion.

2. The practice baseball bat of claim 1.

5. A synthetic resin material is disposed at least at the bottom of the groove.

2. The practice baseball bat of claim 1.

6. The cross-sectional shape of the groove is formed into a trapezoidal or arc shape whose width gradually decreases from the opening to the bottom of the groove.

2. The practice baseball bat of claim 1.

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