Racket Frame

Abstract

A racket frame includes a face portion. The face portion includes an inner circumferential surface, an outer circumferential surface, a first end portion (tip end portion), a second end portion (rear end portion), and a side end portion. The face portion is provided with a plurality of through holes in a circumferential direction of the face portion. Each of the plurality of through holes penetrates the inner circumferential surface and the outer circumferential surface of the face portion. The plurality of through holes include a first hole and a second hole adjacent to each other. The first hole and the second hole are arranged in at least one of the first end portion (tip end portion), the second end portion (rear end portion), and the side end portion, and are inclined such that a distance therebetween becomes shorter from the outer circumferential surface toward the inner circumferential surface.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This nonprovisional application is based on Japanese Patent Application No. 2023-035610 filed on Mar. 8, 2023 with the Japan Patent Office, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a racket frame.

Description of the Background Art

In a racket, a ball-hitting surface is formed by stretching a string in a lengthwise direction and a crosswise direction. For example, in a racket described in Japanese Patent No. 6943608, a plurality of insertion paths through which a string is inserted are formed in a racket frame, and a plurality of strings are formed at unsymmetrical positions on both sides of at least one of the lengthwise direction and the crosswise direction.

Motion of a string to an in-plane direction of a ball-hitting surface is important to improve spin performance. The motion of the string is limited when the string passed through an insertion path (through hole) provided in a racket frame contacts an inner surface of the through hole. Accordingly, it is required to suppress contact of the string with the inner surface of the through hole provided in the racket frame so as not to limit the motion of the string. In the racket described in the publication described above, it is not possible to suppress contact of the string with an inner surface of a through hole in the racket frame. Therefore, the motion of the string is limited, and thus spin performance cannot be improved.

SUMMARY OF THE INVENTION

The present invention has been made in view of the aforementioned problem, and an object thereof is to provide a racket frame that can improve spin performance by suppressing contact of a string with an inner surface of a through hole in the racket frame.

A racket frame of the present invention includes a grip portion, a shaft portion connected to the grip portion, and a face portion connected to the shaft portion. The face portion, the shaft portion, and the grip portion are arranged to be aligned in a first direction. The face portion includes an inner circumferential surface, an outer circumferential surface, a tip end portion located on a side opposite to the grip portion in the first direction, a rear end portion located on a side of the grip portion in the first direction, and a side end portion located in a second direction orthogonal to the first direction. The face portion is provided with a plurality of through holes in a circumferential direction of the face portion. Each of the plurality of through holes penetrates the inner circumferential surface and the outer circumferential surface of the face portion. The plurality of through holes include a first hole and a second hole adjacent to each other. The first hole and the second hole are arranged in at least one of the tip end portion, the rear end portion, and the side end portion, and are inclined such that a distance therebetween becomes shorter from the outer circumferential surface toward the inner circumferential surface.

According to the present invention, spin performance can be improved by suppressing contact of a string with an inner surface of a through hole in the racket frame.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view schematically showing a racket frame according to an embodiment.

FIG. 2 is an enlarged front view schematically showing a racket according to the embodiment.

FIG. 3 is an enlarged view showing a portion III in FIG. 2.

FIG. 4 is an enlarged view showing a portion IV in FIG. 3.

FIG. 5 is an enlarged perspective view schematically showing the positional relation between a string and a plurality of through holes in the racket frame in the racket in the present embodiment.

FIG. 6 is an enlarged view showing a portion VI in FIG. 2.

FIG. 7 is a front view for describing a state where the string is stretched over the racket frame in the racket in the present embodiment.

FIG. 8 is an enlarged front view schematically showing the positional relation between a string and a plurality of through holes in a racket frame in a racket in a comparative example.

FIG. 9 is an enlarged perspective view schematically showing the positional relation between the string and the plurality of through holes in the racket frame in the racket in the comparative example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described based on the drawings. It should be noted that, unless otherwise specified, identical or corresponding parts in the following drawings will be designated by the same reference numerals, and the description thereof will not be repeated.

Referring to FIG. 1, a structure of a racket frame 10 according to the present embodiment will be described. In the following drawings, for convenience of description, a plurality of through holes H are omitted as appropriate. Racket frame 10 according to the present embodiment includes a face portion 1, a shaft portion 2, and a grip portion 3. Face portion 1, shaft portion 2, and grip portion 3 are arranged to be aligned in a first direction (lengthwise direction) D1. Shaft portion 2 is arranged between face portion 1 and grip portion 3 in first direction D1.

The material used for racket frame 10 is CFRP (Carbon Fiber Reinforced Plastic), for example. However, the material used for racket frame 10 is not limited to CFRP. For example, GFRP (Glass Fiber Reinforced Plastic) or the like can be used as the material used for racket frame 10.

Face portion 1 has an elliptical annular shape in plan view. A longitudinal direction of face portion 1 in plan view is parallel to first direction D1. A short direction of face portion 1 in plan view is parallel to a second direction (crosswise direction) D2 orthogonal to first direction D1. A depth direction of face portion 1 in plan view is parallel to a third direction (depth direction) D3 orthogonal to first direction D1 and second direction D2.

Face portion 1 has a first end (tip end) 1a and a second end (rear end) 1b in first direction D1. First end 1a is an end of face portion 1 located on a side opposite to grip portion 3 in first direction D1. First end 1a is located at a foremost part of face portion 1 in first direction D1. Second end 1b is an end located on a side of grip portion 3 in first direction D1. Second end 1b is located at a rearmost part of face portion 1 in first direction D1.

Face portion 1 includes a first end portion (tip end portion) 11 having first end 1a, and a second end portion (rear end portion) 12 having second end 1b. First end portion (tip end portion) 11 is located on the side opposite to grip portion 3 in first direction D1. First end portion 11 extends along a circumferential direction of face portion 1 with first end 1a being located at the center. Second end portion (rear end portion) 12 is located on the side of grip portion 3 in first direction D1. Second end portion 12 extends along the circumferential direction of face portion 1 with second end 1b being located at the center. Second end portion 12 is arranged to be spaced from first end portion 11 in first direction D1. Second end portion 12 is a yoke portion.

Face portion 1 includes a side end portion 13. Side end portion 13 is located in second direction D2 orthogonal to first direction D1. Side end portion 13 has a third end portion (left end portion) 13a and a fourth end portion (right end portion) 13b. Third end portion 13a is arranged between first end portion 11 and second end portion 12, and connects one end of first end portion 11 and one end of second end portion 12. Fourth end portion 13b is arranged between first end portion 11 and second end portion 12, and connects the other end of first end portion 11 and the other end of second end portion 12. Fourth end portion 13b is arranged to be spaced from third end portion 13a in second direction D2.

Face portion 1 includes an inner circumferential surface IS and an outer circumferential surface OS. Each of first end portion 11, second end portion 12, third end portion 13a, and fourth end portion 13b of face portion 1 has inner circumferential surface IS and outer circumferential surface OS. Face portion 1 is provided with the plurality of through holes H in the circumferential direction of face portion 1. The plurality of through holes H are arranged to be spaced in the circumferential direction of face portion 1.

Each of the plurality of through holes H penetrates inner circumferential surface IS and outer circumferential surface OS of face portion 1. Each of the plurality of through holes H has an inner surface. The inner surface of each of the plurality of through holes H penetrates inner circumferential surface IS and outer circumferential surface OS of face portion 1. An inner side end of the inner surface of each of the plurality of through holes H is connected to inner circumferential surface IS of face portion 1, and an outer side end of the inner surface of each of the plurality of through holes H is connected to outer circumferential surface OS of face portion 1. The plurality of through holes H are provided in each of first end portion 11, second end portion 12, third end portion 13a, and fourth end portion 13b.

Each of the plurality of through holes H provided in first end portion 11 faces each of the plurality of through holes H provided in second end portion 12, respectively, in first direction D1. Each of the plurality of through holes H provided in third end portion 13a faces each of the plurality of through holes H provided in fourth end portion 13b, respectively, in second direction D2.

Shaft portion 2 has a first branch member 2A and a second branch member 2B. Grip portion 3 is a portion gripped by a user of a racket 100. Grip portion 3 extends along a longitudinal direction of racket frame 10. Grip portion 3 is located on a side of racket frame 10 closer to second end portion 12.

Referring to FIGS. 2 to 7, structures of racket frame 10 and racket 100 according to the present embodiment will be described.

Referring to FIGS. 2 and 7, racket 100 according to the present embodiment includes racket frame 10 and a string 20. String 20 is stretched over face portion 1 of racket frame 10. String 20 is passed through each of the plurality of through holes H. String 20 has a plurality of main string portions 201, a plurality of cross string portions 202, and a plurality of turned portions 203.

The material for string 20 is polyester, nylon, or the like, for example. String 20 has a diameter of more than or equal to 1.20 mm and less than or equal to 1.30 mm, for example. String 20 may have a diameter of 1.20 mm, 1.25 mm, 1.30 mm, or the like, for example. String 20 has a tension of more than or equal to 40 lbs and less than or equal to 60 lbs, for example. String 20 may have a tension of 40 lbs, 50 lbs, 60 lbs, or the like, for example.

The plurality of main string portions 201 extend between each of the plurality of through holes H arranged in first end portion 11 and each of the plurality of through holes H arranged in second end portion 12, along first direction D1. The plurality of cross string portions 202 extend between each of the plurality of through holes H arranged in third end portion 13a and each of the plurality of through holes H arranged in fourth end portion 13b, along second direction D2.

The plurality of turned portions 203 are arranged on a side more outward than the plurality of through holes H. The plurality of turned portions 203 are each arranged between through holes H adjacent in the circumferential direction of face portion 1, in each of first end portion 11, second end portion 12, third end portion 13a, and fourth end portion 13b. That is, string 20 is turned on the side more outward than through holes H adjacent in the circumferential direction of face portion 1, in each of first end portion 11, second end portion 12, third end portion 13a, and fourth end portion 13b.

Referring to FIGS. 2 to 6, details of the plurality of through holes H provided in face portion 1 of racket frame 10 will be described.

Referring to FIGS. 2 and 3, face portion 1 of racket frame 10 further includes grommets 15. Grommets 15 protect string 20. The material for grommets 15 is a thermoplastic resin, a thermosetting resin, rubber, or the like, for example. The material for grommets 15 may be a nylon resin, for example. One through hole H is provided to one grommet 15. The minimum width of a hole of each grommet 15 is larger than the width of string 20.

The plurality of through holes H are provided in line symmetry with respect to a center line CL (imaginary line) of face portion 1 passing through first end 1a and second end 1b. It should be noted that center line CL passes through the central axis of grip portion 3. The plurality of through holes H include a first hole H1 and a second hole H2. First hole H1 and second hole H2 are arranged in at least one of first end portion (tip end portion) 11, second end portion (rear end portion) 12, and side end portion 13. In the present embodiment, first hole H1 and second hole H2 are arranged in all of first end portion (tip end portion) 11, second end portion (rear end portion) 12, and side end portion 13. Further, the plurality of through holes H include a third hole H3 and a fourth hole H4. First hole H1, second hole H2, third hole H3, and fourth hole H4 are holes through which main string portions 201 of string 20 are passed.

First hole H1, second hole H2, third hole H3, and fourth hole H4 arranged in first end portion (tip end portion) 11 are arranged to be distant from center line CL in this order.

Referring to FIGS. 3 and 4, first hole H1 and second hole H2 are adjacent to each other. First hole H1 is arranged at a position closest to center line CL. Second hole H2 is arranged on a side opposite to center line CL with respect to first hole H1. First hole H1 and second hole H2 are inclined such that a distance therebetween becomes shorter from outer circumferential surface OS toward inner circumferential surface IS. A center line passing through the center of first hole H1 and a center line passing through the center of second hole H2 are respectively inclined on opposite sides with respect to a direction parallel to center line CL of face portion 1.

Third hole H3 and fourth hole H4 are adjacent to each other. Third hole H3 is arranged adjacent to second hole H2. Third hole H3 is arranged on a side opposite to first hole H1 with respect to second hole H2. Fourth hole H4 is arranged on a side opposite to second hole H2 with respect to third hole H3. Third hole H3 and fourth hole H4 are arranged in first end portion (tip end portion) 11. Third hole H3 and fourth hole H4 are inclined such that a distance therebetween becomes shorter from outer circumferential surface OS toward inner circumferential surface IS. A center line passing through the center of third hole H3 and a center line passing through the center of fourth hole H4 are respectively inclined on opposite sides with respect to the direction parallel to center line CL of face portion 1.

With respect to center line CL of face portion 1 extending along first direction D1, an absolute value of an angle of inclination of first hole H1 is less than or equal to an absolute value of an angle of inclination of second hole H2, and an absolute value of an angle of inclination of third hole H3 is less than or equal to an absolute value of an angle of inclination of fourth hole H4. Preferably, with respect to center line CL, the absolute value of the angle of inclination of first hole H1 is less than the absolute value of the angle of inclination of second hole H2, and the absolute value of the angle of inclination of third hole H3 is less than the absolute value of the angle of inclination of fourth hole H4.

The angle of inclination of each of first hole H1 and third hole H3 is more than or equal to 2° and less than or equal to 4°, for example, in a counterclockwise direction, and the angle of inclination of each of second hole H2 and fourth hole H4 is more than or equal to 3° and less than or equal to 5°, for example, in a clockwise direction. Preferably, the angle of inclination of each of first hole H1 and third hole H3 is 3° in the counterclockwise direction, and the angle of inclination of each of second hole H2 and fourth hole H4 is 4° in the clockwise direction. In the present embodiment, the counterclockwise direction is specified as + (plus), and the clockwise direction is specified as − (minus).

Referring to FIG. 5, each of the plurality of through holes H has a circular planar shape, for example. That is, in this case, each of front surfaces and back surfaces of the plurality of through holes H has a circular planar shape. It should be noted that the planar shape of through holes H is not limited to circular, and may be X-shaped, for example.

Further, the plurality of through holes H include first hole H1, second hole H2, third hole H3, and fourth hole H4 arranged in second end portion (rear end portion) 12. First hole H1, second hole H2, third hole H3, and fourth hole H4 arranged in second end portion (rear end portion) 12 are arranged in the same manner as in first end portion (tip end portion) 11.

Referring to FIGS. 2 and 6, the plurality of through holes H include first hole H1, second hole H2, third hole H3, and fourth hole H4 arranged in side end portion 13. In the present embodiment, first hole H1, second hole H2, third hole H3, and fourth hole H4 are provided in third end portion 13a. First hole H1, second hole H2, third hole H3, and fourth hole H4 may be provided in fourth end portion 13b. First hole H1, second hole H2, third hole H3, and fourth hole H4 are holes through which cross string portions 202 of string 20 are passed.

Arrangement of first hole H1, second hole H2, third hole H3, and fourth hole H4 arranged in side end portion 13 will be described. First hole H1 and second hole H2 are adjacent to each other. First hole H1 is arranged at a position closest to the center of face portion 1 in first direction D1. Second hole H2 is arranged on a side opposite to the center of face portion 1 in first direction D1 with respect to first hole H1. First hole H1 and second hole H2 are inclined such that a distance therebetween becomes shorter from outer circumferential surface OS toward inner circumferential surface IS. A center line passing through the center of first hole H1 and a center line passing through the center of second hole H2 are inclined with respect to a direction parallel to the center of face portion 1 in first direction D1.

Third hole H3 and fourth hole H4 are adjacent to each other. Third hole H3 is arranged adjacent to fourth hole H4. Third hole H3 is arranged on a side opposite to first hole H1 with respect to second hole H2. Fourth hole H4 is arranged on a side opposite to second hole H2 with respect to third hole H3. Third hole H3 and fourth hole H4 are inclined such that a distance therebetween becomes shorter from outer circumferential surface OS toward inner circumferential surface IS. A center line passing through the center of third hole H3 and a center line passing through the center of fourth hole H4 are inclined with respect to the direction parallel to the center of face portion 1 in first direction D1.

Referring to FIG. 7, a state where string 20 is stretched over racket frame 10 in racket 100 in the present embodiment will be described. A state where string 20 is stretched in first end portion (tip end portion) 11 and second end portion (rear end portion) 12 in face portion 1 of racket frame 10 will be described. The plurality of turned portions 203 of string 20 include a first turned portion 203a, a second turned portion 203b, a third turned portion 203c, a fourth turned portion 203d, and a fifth turned portion 203e. Main string portion 201 passing through first hole H1 is connected to main string portion 201 passing through second hole H2 via first turned portion 203a. Main string portion 201 passing through second hole H2 is connected to main string portion 201 passing through third hole H3 via second turned portion 203b. Main string portion 201 passing through third hole H3 is connected to main string portion 201 passing through fourth hole H4 via third turned portion 203c. Main string portion 201 passing through fourth hole H4 is connected to main string portion 201 passing through through hole H on a side more outward than fourth hole H4 via fourth turned portion 203d. Main string portion 201 passing through through hole H on the side more outward than fourth hole H4 is connected to main string portion 201 passing through through hole H on a further outward side via fifth turned portion 203e. Further, although not shown, string 20 is also stretched in the same manner in side end portion 13. That is, string 20 is stretched in the same manner in third end portion (left end portion) 13a and fourth end portion (right end portion) 13b

It should be noted that, in the above description, first hole H1, second hole H2, third hole H3, and fourth hole H4 are arranged on one side with respect to center line CL. However, first hole H1, second hole H2, third hole H3, and fourth hole H4 may be arranged such that first hole H1 and second hole H2 sandwich center line CL therebetween and are symmetrical with respect to center line CL.

Next, the function and effect of the embodiment will be described in comparison with a comparative example.

Referring to FIGS. 8 and 9, in racket frame 10 in the comparative example, each of first hole H1, second hole H2, third hole H3, and fourth hole H4 extends along center line CL of face portion 1. Accordingly, when a ball-hitting surface is formed by stretching string 20, string 20 contacts an inner circumferential surface IS side of an inner surface of each of first hole H1 and second hole H2 located on both sides of turned portion 203, due to the tension of string 20.

In racket frame 10 according to the present embodiment, first hole H1 and second hole H2 are inclined such that the distance therebetween becomes shorter from outer circumferential surface OS toward inner circumferential surface IS. Accordingly, when first hole H1 and second hole H2 are located on both sides of turned portion 203, it is possible to suppress contact of string 20 with an inner circumferential surface IS side of inner surfaces of first hole H1 and second hole H2. Therefore, spin performance can be improved by suppressing contact of string 20 with the inner surface of through hole H in racket frame 10.

Further, first hole H1 and second hole H2 are arranged in at least one of first end portion (tip end portion) 11, second end portion (rear end portion) 12, and side end portion 13. Since lengthwise string 20 (main string portions 201) in first end portion (tip end portion) 11 is close to a hitting point, it has a high impact on spin performance. Therefore, by arranging first hole H1 and second hole H2 in first end portion (tip end portion) 11, motion of string 20 to an in-plane direction of the ball-hitting surface is ensured, and thereby spin performance can be improved.

Further, lengthwise string 20 (main string portions 201) has a higher impact on spin performance than crosswise string 20 (cross string portions 202). Therefore, by arranging first hole H1 and second hole H2 in second end portion (rear end portion) 12, motion of string 20 to the in-plane direction of the ball-hitting surface is ensured, and thereby spin performance can be improved.

Further, crosswise string 20 (cross string portions 202) has an impact on spin performance, although the impact is lower than that of lengthwise string 20 (main string portions 201). Therefore, by arranging first hole H1 and second hole H2 in side end portion 13, motion of string 20 to the in-plane direction of the ball-hitting surface is ensured, and thereby spin performance can be improved.

Further, external appearance can be improved by suppressing contact of string 20 with the inner surface of through hole H in racket frame 10.

Further, by suppressing contact of string 20 with the inner surface of through hole H in racket frame 10, damage to grommet 15 and string 20 can be suppressed, and thereby durability of grommet 15 and string 20 can be improved.

In racket frame 10 according to the present embodiment, third hole H3 and fourth hole H4 are inclined such that the distance therebetween becomes shorter from outer circumferential surface OS toward inner circumferential surface IS. Accordingly, when third hole H3 and fourth hole H4 are located on both sides of turned portion 203, it is possible to suppress contact of string 20 with an inner circumferential surface IS side of inner circumference of third hole H3 and fourth hole H4. Therefore, spin performance can be further improved by further suppressing contact of string 20 with the inner surface of through hole H in racket frame 10.

In racket frame 10 according to the present embodiment, with respect to center line CL of face portion 1 extending along first direction D1, the absolute value of the angle of inclination of first hole H1 is less than or equal to the absolute value of the angle of inclination of second hole H2, and the absolute value of the angle of inclination of third hole H3 is less than or equal to the absolute value of the angle of inclination of fourth hole H4. The inventors of the present invention have found that this can effectively suppress contact of string 20 with the inner surface of through hole H.

In racket frame 10 according to the present embodiment, with respect to center line CL, the absolute value of the angle of inclination of first hole H1 is less than the absolute value of the angle of inclination of second hole H2, and the absolute value of the angle of inclination of third hole H3 is less than the absolute value of the angle of inclination of fourth hole H4. The inventors of the present invention have found that this can effectively suppress contact of string 20 with the inner surface of through hole H.

In racket frame 10 according to the present embodiment, the angle of inclination of each of first hole H1 and third hole H3 is more than or equal to 2° and less than or equal to 4° in the counterclockwise direction, and the angle of inclination of each of second hole H2 and fourth hole H4 is more than or equal to 3° and less than or equal to 5° in the clockwise direction. The inventors of the present invention have found that this can effectively suppress contact of string 20 with the inner surface of through hole H.

Racket 100 according to the present embodiment includes racket frame 10 described above and string 20 passed through the plurality of through holes H. Accordingly, spin performance can be improved by suppressing contact of string 20 with the inner surface of through hole H in racket frame 10.

Example

Next, examples of the racket frame and the racket according to the present embodiment will be described in comparison with comparative examples.

In the present example, a state where a ball-hitting surface was formed by stretching string 20 was investigated for Examples 1 to 5, in comparison with Comparative Examples 1 to 6. Examples 1 to 5 have the same structures as those of the racket frame and the racket according to the present embodiment. In Examples 1 to 5, the angle of inclination of each of the first hole and the third hole is more than or equal to 2° and less than or equal to 4° in the counterclockwise direction, and the angle of inclination of each of the second hole and the fourth hole is more than or equal to 3° and less than or equal to 5° in the clockwise direction.

In Comparative Example 1, the angle of inclination of each of the first hole and the third hole is 1° in the counterclockwise direction, and the angle of inclination of each of the second hole and the fourth hole is 1 in the clockwise direction. In Comparative Example 2, the angle of inclination of each of the first hole and the third hole is 5° in the counterclockwise direction, and the angle of inclination of each of the second hole and the fourth hole is 5° in the clockwise direction. In Comparative Example 3, the angle of inclination of each of the first hole and the third hole is 10° in the counterclockwise direction, and the angle of inclination of each of the second hole and the fourth hole is 10° in the clockwise direction.

In Comparative Example 4, the angle of inclination of each of the first hole and the third hole is 1° in the counterclockwise direction, and the angle of inclination of each of the second hole and the fourth hole is 1° in the clockwise direction. In Comparative Example 5, the angle of inclination of each of the first hole and the third hole is 5° in the counterclockwise direction, and the angle of inclination of each of the second hole and the fourth hole is 5 in the clockwise direction. In Comparative Example 6, the angle of inclination of each of the first hole and the third hole is 10° in the counterclockwise direction, and the angle of inclination of each of the second hole and the fourth hole is 10° in the clockwise direction.

In Example 1, the material for the string is polyester, the string has a diameter of 1.25 mm, and has a tension of 50 lbs. In Example 2, the material for the string is polyester, the string has a diameter of 1.25 mm, and has a tension of 60 lbs. In Example 3, the material for the string is polyester, the string has a diameter of 1.20 mm, and has a tension of 50 lbs. In Example 4, the material for the string is polyester, the string has a diameter of 1.20 mm, and has a tension of 60 lbs. In Example 5, the material for the string is nylon (multifilament), the string has a diameter of 1.30 mm, and has a tension of 40 lbs.

In Comparative Examples 1 to 3, the material for the string is polyester, the string has a diameter of 1.25 mm, and has a tension of 50 lbs. In Comparative Examples 4 to 6, the material for the string is polyester, the string has a diameter of 1.25 mm, and has a tension of 60 lbs.

In all of Comparative Examples 1 to 6, the string contacted an inner circumferential side of the inner surfaces of the first hole, the second hole, the third hole, and the fourth hole. In contrast, in all of Examples 1 to 5, the string did not contact an inner circumferential side of the inner surfaces of the first hole, the second hole, the third hole, and the fourth hole. Further, in all of Examples 1 to 5, the string was located in the vicinity of the center of each of the first hole, the second hole, the third hole, and the fourth hole, on a side opposite to the turned portions.

Although the embodiment of the present invention has been described, it should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present invention is defined by the scope of the claims, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.

Claims

1. A racket frame comprising: a grip portion;a shaft portion connected to the grip portion; anda face portion connected to the shaft portion, whereinthe face portion, the shaft portion, and the grip portion are arranged to be aligned in a first direction,the face portion includes an inner circumferential surface, an outer circumferential surface, a tip end portion located on a side opposite to the grip portion in the first direction, a rear end portion located on a side of the grip portion in the first direction, and a side end portion located in a second direction orthogonal to the first direction,the face portion is provided with a plurality of through holes in a circumferential direction of the face portion,each of the plurality of through holes penetrates the inner circumferential surface and the outer circumferential surface of the face portion,the plurality of through holes include a first hole and a second hole adjacent to each other, andthe first hole and the second hole are arranged in at least one of the tip end portion, the rear end portion, and the side end portion, and are inclined such that a distance therebetween becomes shorter from the outer circumferential surface toward the inner circumferential surface.

2. The racket frame according to claim 1, wherein the plurality of through holes include a third hole and a fourth hole adjacent to each other,the third hole is arranged adjacent to the second hole,the fourth hole is arranged on a side opposite to the second hole with respect to the third hole, andthe third hole and the fourth hole are arranged in the tip end portion, and are inclined such that a distance therebetween becomes shorter from the outer circumferential surface toward the inner circumferential surface.

3. The racket frame according to claim 2, wherein, with respect to a center line of the face portion extending along the first direction, an absolute value of an angle of inclination of the first hole is less than or equal to an absolute value of an angle of inclination of the second hole, and an absolute value of an angle of inclination of the third hole is less than or equal to an absolute value of an angle of inclination of the fourth hole.

4. The racket frame according to claim 3, wherein, with respect to the center line, the absolute value of the angle of inclination of the first hole is less than the absolute value of the angle of inclination of the second hole, and the absolute value of the angle of inclination of the third hole is less than the absolute value of the angle of inclination of the fourth hole.

5. The racket frame according to claim 4, wherein the angle of inclination of each of the first hole and the third hole is more than or equal to 2° and less than or equal to 4° in a counterclockwise direction, andthe angle of inclination of each of the second hole and the fourth hole is more than or equal to 3° and less than or equal to 5° in a clockwise direction.