Racket frame

Abstract

To make it possible to improve spin performance by suppressing abutment of a string to a wall surface of a through hole of a racket frame.SOLUTION: A racket frame 10 includes a face part 1. The face part 1 includes: an inner peripheral surface IS; an outer peripheral surface OS; a first end (end part) 11; a second end (rear end part) 12; and a side end part 13. In the face part 1, a plurality of through holes H is provided in a circumferential direction of the face part 1. Each of the plurality of through holes H goes through an inner peripheral surface IS and an outer peripheral surface OS of the face part 1. The plurality of through holes H includes a first hole H1 and a second hole H2 adjacent to each other. The first hole H1 and the second hole H2 are arranged in one of a first end (an end) 11, a second end (a rear end) 12 and a side end 13, and tilts so that a distance to each other becomes shorter from the outer peripheral surface OS to the inner peripheral surface IS.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a racket frame. [Background technology]

[0002] A hitting surface of a racket is formed by stringing the racket vertically and horizontally. For example, in the racket described in Japanese Patent No. 6943608 (Patent Document 1), a plurality of string insertion passages are formed in the racket frame, and a plurality of strings are formed in asymmetric positions on at least one of the vertical and horizontal sides. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6943608 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to improve spin performance, the movement of the string in the in-plane direction of the hitting surface is important. If the string passed through an insertion passage (through hole) provided in the racket frame hits the inner surface of the through hole, the movement of the string is restricted. Therefore, it is necessary to prevent the string from hitting the inner surface of the through hole provided in the racket frame so that the movement of the string is not restricted. With the racket described in the above publication, it is not possible to prevent the string from hitting the inner surface of the through hole of the racket frame. Therefore, since the movement of the string is restricted, it is not possible to improve spin performance.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a racket frame that can improve spin performance by preventing the strings from hitting the inner surface of the through holes in the racket frame. [Means for solving the problem]

[0006] The 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 side by side in a first direction. The face portion includes an inner peripheral surface, an outer peripheral surface, a tip portion located on the opposite side to the grip portion in the first direction, a rear end portion located on the grip portion side in the first direction, and a side end portion located in a second direction perpendicular to the first direction. The face portion is provided with a plurality of through holes in the circumferential direction of the face portion. Each of the plurality of through holes penetrates the inner peripheral surface and the outer peripheral surface of the face portion. The plurality of through holes includes a first hole and a second hole adjacent to each other. The first hole and the second hole are arranged at least in one of the tip portion, the rear end portion, and the side end portion, and are inclined so that the distance between them becomes closer from the outer peripheral surface toward the inner peripheral surface. The multiple through holes include a third hole and a fourth hole adjacent to each other. The third hole is disposed adjacent to the second hole. The fourth hole is disposed on the opposite side of the third hole from the second hole. The third hole and the fourth hole are disposed at the tip portion and are inclined so that the distance between them decreases from the outer peripheral surface toward the inner peripheral surface. The first hole and the second hole are disposed at the tip portion. The second hole and the third hole are inclined so that the distance between them increases from the outer peripheral surface toward the inner peripheral surface. Effect of the Invention

[0007] According to the present invention, the spin performance can be improved by preventing the string from hitting the inner surface of the through-hole of the racket frame. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a front view showing a schematic view of a racket frame according to the embodiment. [Diagram 2] 1 is an enlarged front view showing a schematic view of a racket according to an embodiment; [Diagram 3] FIG. 3 is an enlarged view showing a portion III in FIG. [Figure 4] FIG. 4 is an enlarged view showing a portion IV in FIG. [Diagram 5] 2 is an enlarged perspective view showing a schematic positional relationship between a plurality of through holes in a racket frame of the racket according to the present embodiment and strings. FIG. [Figure 6] FIG. 3 is an enlarged view showing a portion VI in FIG. [Figure 7]FIG. 2 is a front view for explaining a state in which strings are strung on a racket frame of the racket of the present embodiment. [Figure 8] FIG. 11 is an enlarged front view showing a schematic positional relationship between a plurality of through holes in a racket frame of a comparative example and strings. [Figure 9] FIG. 13 is an enlarged perspective view showing a schematic positional relationship between a plurality of through holes in a racket frame of a comparative example and strings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference characters unless otherwise specified, and the description thereof will not be repeated.

[0010] The structure of a racket frame 10 according to this embodiment will be described with reference to FIG. 1. In the following figures, for the sake of convenience, a plurality of through holes H are omitted as appropriate. The racket frame 10 according to this embodiment includes a face portion 1, a shaft portion 2, and a grip portion 3. The face portion 1, the shaft portion 2, and the grip portion 3 are arranged side by side in a first direction (vertical direction) D1. The shaft portion 2 is arranged between the face portion 1 and the grip portion 3 in the first direction D1.

[0011] The material used for the racket frame 10 is, for example, CFRP (Carbon Fiber Reinforced Plastic). However, the material used for the racket frame 10 is not limited to CFRP. For example, the material used for the racket frame 10 can be GFRP (Glass Fiber Reinforced Plastic) or the like.

[0012] The face portion 1 has an elliptical ring shape in a plan view. The longitudinal direction of the face portion 1 in the plan view is along a first direction D1. The lateral direction of the face portion 1 in the plan view is along a second direction (lateral direction) D2 perpendicular to the first direction D1. The depth direction of the face portion 1 in the plan view is along a third direction (thickness direction) D3 perpendicular to the first direction D1 and the second direction D2.

[0013] The face portion 1 has a first end (front end) 1a and a second end (rear end) 1b in the first direction D1. The first end 1a is an end of the face portion 1 located on the opposite side to the grip portion 3 in the first direction D1. The first end 1a is located at the front end of the face portion 1 in the first direction D1. The second end 1b is an end located on the grip portion 3 side in the first direction D1. The second end 1b is located at the rear end of the face portion 1 in the first direction D1.

[0014] The face portion 1 includes a first end portion (tip portion) 11 having a first end 1a, and a second end portion (rear end portion) 12 having a second end 1b. The first end portion (tip portion) 11 is located on the opposite side to the grip portion 3 in the first direction D1. The first end portion 11 extends along the circumferential direction of the face portion 1 with the first end portion 1a as the center. The second end portion (rear end portion) 12 is located on the grip portion 3 side in the first direction D1. The second end portion 12 extends along the circumferential direction of the face portion 1 with the second end portion 1b as the center. The second end portion 12 is disposed at an interval from the first end portion 11 in the first direction D1. The second end portion 12 is a yoke portion.

[0015] The face portion 1 includes a side end portion 13. The side end portion 13 is located in a second direction D2 perpendicular to the first direction D1. The side end portion 13 has a third end portion (left end portion) 13a and a fourth end portion (right end portion) 13b. The third end portion 13a is disposed between the first end portion 11 and the second end portion 12, and connects one end of the first end portion 11 to one end of the second end portion 12. The fourth end portion 13b is disposed between the first end portion 11 and the second end portion 12, and connects the other end of the first end portion 11 to the other end of the second end portion 12. The fourth end portion 13b is disposed at a distance from the third end portion 13a in the second direction D2.

[0016] The face portion 1 includes an inner peripheral surface IS and an outer peripheral surface OS. Each of a first end portion 11, a second end portion 12, a third end portion 13a, and a fourth end portion 13b of the face portion 1 has an inner peripheral surface IS and an outer peripheral surface OS. A plurality of through holes H are provided in the face portion 1 in the circumferential direction of the face portion 1. The plurality of through holes H are arranged at intervals in the circumferential direction of the face portion 1.

[0017] Each of the multiple through holes H penetrates the inner peripheral surface IS and the outer peripheral surface OS of the face portion 1. Each of the multiple through holes H has an inner surface. The inner surface of each of the multiple through holes H penetrates the inner peripheral surface IS and the outer peripheral surface OS of the face portion 1. An inner end of the inner surface of each of the multiple through holes H is connected to the inner peripheral surface IS of the face portion 1, and an outer end of the inner surface of each of the multiple through holes H is connected to the outer peripheral surface OS of the face portion 1. The multiple through holes H are provided in each of the first end portion 11, the second end portion 12, the third end portion 13a, and the fourth end portion 13b.

[0018] Each of the plurality of through holes H provided at the first end 11 and each of the plurality of through holes H provided at the second end 12 face each other in the first direction D1. Each of the plurality of through holes H provided at the third end 13a and each of the plurality of through holes H provided at the fourth end 13b face each other in the second direction D2.

[0019] The shaft portion 2 has a first branch member 2A and a second branch member 2B. The grip portion 3 is the portion that is gripped by a user of the racket 100. The grip portion 3 extends along the longitudinal direction of the racket frame 10. The grip portion 3 is located on the second end 12 side of the racket frame 10.

[0020] The structures of the racket frame 10 and racket 100 according to the present embodiment will be described with reference to FIGS.

[0021] 2 and 7, a racket 100 according to this embodiment includes a racket frame 10 and a string 20. The string 20 is strung on a face portion 1 of the racket frame 10. The string 20 is passed through each of a plurality of through-holes H. The string 20 has a plurality of main string portions 201, a plurality of cross string portions 202, and a plurality of folded-back portions 203.

[0022] The material of the string 20 is, for example, polyester, nylon, etc. The diameter of the string 20 is, for example, 1.20 mm or more and 1.30 mm or less. The diameter of the string 20 may be, for example, 1.20 mm, 1.25 mm, 1.30 mm, etc. The tension of the string 20 is, for example, 40 lbs or more and 60 lbs or less. The tension of the string 20 may be, for example, 40 lbs, 50 lbs, 60 lbs, etc.

[0023] The main string portions 201 extend along a first direction D1 between each of the through holes H arranged at the first end 11 and each of the through holes H arranged at the second end 12. The cross string portions 202 extend along a second direction D2 between each of the through holes H arranged at the third end 13a and each of the through holes H arranged at the fourth end 13b.

[0024] The multiple folded-back portions 203 are disposed outside the multiple through holes H. The multiple folded-back portions 203 are disposed between adjacent through holes H in the circumferential direction of the face portion 1 at each of the first end 11, the second end 12, the third end 13a, and the fourth end 13b. In other words, the string 20 is folded back outside the adjacent through holes H in the circumferential direction of the face portion 1 at each of the first end 11, the second end 12, the third end 13a, and the fourth end 13b.

[0025] The multiple through-holes H provided in the face portion 1 of the racket frame 10 will be described in detail with reference to FIGS.

[0026] 2 and 3, the face portion 1 of the racket frame 10 further includes a grommet 15. The grommet 15 protects the string 20. The material of the grommet 15 is, for example, a thermoplastic resin, a thermosetting resin, or rubber. The material of the grommet 15 may be, for example, a nylon resin. One through hole H is provided in one grommet 15. The minimum width of the hole of the grommet 15 is larger than the width of the string 20.

[0027] The multiple through holes H are provided symmetrically with respect to a center line CL (virtual line) of the face portion 1 passing through the first end 1a and the second end 1b. The center line CL passes through the central axis of the grip portion 3. The multiple through holes H include a first hole H1 and a second hole H2. The first hole H1 and the second hole H2 are arranged at least in one of the first end (tip portion) 11, the second end (back end portion) 12, and the side end portion 13. In this embodiment, the first hole H1 and the second hole H2 are arranged at all of the first end (tip portion) 11, the second end (back end portion) 12, and the side end portion 13. The multiple through holes H also include a third hole H3 and a fourth hole H4. The first hole H1, the second hole H2, the third hole H3, and the fourth hole H4 are holes through which the main string portion 201 of the string 20 is passed.

[0028] The first hole H1, the second hole H2, the third hole H3 and the fourth hole H4, which are arranged at the first end (tip portion) 11, are arranged in this order so as to be farther away from the center line CL.

[0029] 3 and 4, the first hole H1 and the second hole H2 are adjacent to each other. The first hole H1 is disposed at a position closest to the center line CL. The second hole H2 is disposed on the opposite side of the center line CL with respect to the first hole H1. The first hole H1 and the second hole H2 are inclined so that the distance between them decreases from the outer peripheral surface OS toward the inner peripheral surface IS. The center line passing through the center of the first hole H1 and the center line passing through the center of the second hole H2 are inclined in opposite directions with respect to the direction along the center line CL of the face portion 1.

[0030] The third hole H3 and the fourth hole H4 are adjacent to each other. The third hole H3 is arranged so as to be adjacent to the second hole H2. The third hole H3 is arranged on the opposite side of the second hole H2 from the first hole H1. The fourth hole H4 is arranged on the opposite side of the third hole H3 from the second hole H2. The third hole H3 and the fourth hole H4 are arranged at the first end (tip portion) 11. The third hole H3 and the fourth hole H4 are inclined so that the distance between them becomes closer from the outer peripheral surface OS toward the inner peripheral surface IS. The center line passing through the center of the third hole H3 and the center line passing through the center of the fourth hole H4 are inclined in opposite directions to each other with respect to the direction along the center line CL of the face portion 1.

[0031] The absolute value of the inclination angle of the first hole H1 with respect to the center line CL of the face portion 1 extending along the first direction D1 is equal to or less than the absolute value of the inclination angle of the second hole H2, and the absolute value of the inclination angle of the third hole H3 is equal to or less than the absolute value of the inclination angle of the fourth hole H4. Preferably, the absolute value of the inclination angle of the first hole H1 with respect to the center line CL is smaller than the absolute value of the inclination angle of the second hole H2, and the absolute value of the inclination angle of the third hole H3 is smaller than the absolute value of the inclination angle of the fourth hole H4.

[0032] The inclination angle of each of the first hole H1 and the third hole H3 is, for example, 2° or more and 4° or less in the counterclockwise direction, and the inclination angle of each of the second hole H2 and the fourth hole H4 is, for example, 3° or more and 5° or less in the clockwise direction. Preferably, the inclination angle of each of the first hole H1 and the third hole H3 is 3° in the counterclockwise direction, and the inclination angle of each of the second hole H2 and the fourth hole H4 is 4° in the clockwise direction. In this embodiment, the counterclockwise direction is defined as + (plus) and the clockwise direction is defined as - (minus).

[0033] 5, the planar shape of each of the plurality of through holes H is, for example, a circular shape. That is, in this case, the planar shape of each of the front and back surfaces of the plurality of through holes H is a circular shape. Note that the planar shape of the through holes H is not limited to a circular shape and may be, for example, an X-shape.

[0034] The multiple through holes H include a first hole H1, a second hole H2, a third hole H3, and a fourth hole H4, which are arranged at the second end (rear end) 12. The first hole H1, the second hole H2, the third hole H3, and the fourth hole H4, which are arranged at the second end (rear end) 12, are arranged in the same manner as at the first end (tip portion) 11.

[0035] 2 and 6, the multiple through holes H include a first hole H1, a second hole H2, a third hole H3, and a fourth hole H4 arranged at the side end 13. In this embodiment, the first hole H1, the second hole H2, the third hole H3, and the fourth hole H4 are provided at the third end 13a. The first hole H1, the second hole H2, the third hole H3, and the fourth hole H4 may be provided at the fourth end 13b. The first hole H1, the second hole H2, the third hole H3, and the fourth hole H4 are holes through which the cross string portion 202 of the string 20 is passed.

[0036] The arrangement of the first hole H1, the second hole H2, the third hole H3, and the fourth hole H4 arranged at the side end 13 will be described. The first hole H1 and the second hole H2 are adjacent to each other. The first hole H1 is arranged at a position closest to the center of the face portion 1 in the first direction D1. The second hole H2 is arranged on the opposite side of the center of the face portion 1 in the first direction D1 with respect to the first hole H1. The first hole H1 and the second hole H2 are inclined so that the distance between them becomes closer from the outer peripheral surface OS toward the inner peripheral surface IS. The center line passing through the center of the first hole H1 and the center line passing through the center of the second hole H2 are inclined with respect to the direction along the center of the face portion 1 in the first direction D1.

[0037] The third hole H3 and the fourth hole H4 are adjacent to each other. The third hole H3 is arranged so as to be adjacent to the fourth hole H4. The third hole H3 is arranged on the opposite side of the second hole H2 from the first hole H1. The fourth hole H4 is arranged on the opposite side of the third hole H3 from the second hole H2. The third hole H3 and the fourth hole H4 are inclined so that the distance between them becomes closer from the outer peripheral surface OS toward the inner peripheral surface IS. The center line passing through the center of the third hole H3 and the center line passing through the center of the fourth hole H4 are inclined with respect to the direction along the center of the face portion 1 in the first direction D1.

[0038] With reference to FIG. 7, a state in which the string 20 is strung on the racket frame 10 of the racket 100 of this embodiment will be described. A state in which the string 20 is strung on the first end (front end) 11 and the second end (rear end) 12 of the face portion 1 of the racket frame 10 will be described. The multiple turn-up portions 203 of the string 20 include a first turn-up portion 203a, a second turn-up portion 203b, a third turn-up portion 203c, a fourth turn-up portion 203d, and a fifth turn-up portion 203e. The main string portion 201 passing through the first hole H1 and the main string portion 201 passing through the second hole H2 are connected via the first turn-up portion 203a. The main string portion 201 passing through the second hole H2 and the main string portion 201 passing through the third hole H3 are connected via the second turn-up portion 203b. The main string portion 201 passing through the third hole H3 and the main string portion 201 passing through the fourth hole H4 are connected via a third folded portion 203c. The main string portion 201 passing through the fourth hole H4 and the main string portion 201 passing through the through hole H on the outside of the fourth hole H4 are connected via a fourth folded portion 203d. The main string portion 201 passing through the through hole H on the outside of the fourth hole H4 and the main string portion 201 passing through the through hole H on the further outside are connected via a fifth folded portion 203e. Although not shown, a string 20 is also strung on the side end portion 13 in the same manner. That is, the string 20 is also strung on the third end portion (left end portion) 13a and the fourth end portion (right end portion) 13b in the same manner.

[0039] In the above, the first hole H1, the second hole H2, the third hole H3, and the fourth hole H4 are arranged on one side of the center line CL. However, the first hole H1, the second hole H2, the third hole H3, and the fourth hole H4 may be arranged symmetrically with respect to the center line CL with the first hole H1 and the second hole H2 sandwiching the center line CL.

[0040] Next, the effects of the embodiment will be described in comparison with a comparative example.

[0041] 8 and 9, in the racket frame 10 of the comparative example, the first hole H1, the second hole H2, the third hole H3, and the fourth hole H4 each extend along the center line CL of the face portion 1. Therefore, when the ball hitting surface is formed by stringing the strings 20, the tension of the strings 20 causes the strings 20 to hit the inner circumferential surfaces IS of the inner surfaces of the first hole H1 and the second hole H2 located on both sides of the turn-back portion 203.

[0042] In the racket frame 10 according to this embodiment, the first hole H1 and the second hole H2 are inclined so that the distance between them decreases from the outer peripheral surface OS toward the inner peripheral surface IS. Therefore, when the first hole H1 and the second hole H2 are located on both sides of the folded-back portion 203, it is possible to prevent the string 20 from hitting the inner peripheral surface IS side of the inner surfaces of the first hole H1 and the second hole H2. Therefore, by preventing the string 20 from hitting the inner surfaces of the through-hole H of the racket frame 10, it is possible to improve the spin performance.

[0043] Moreover, the first hole H1 and the second hole H2 are disposed at least in one of the first end (tip portion) 11, the second end (butt portion) 12, and the side end 13. The vertical string 20 (main string portion 201) at the first end (tip portion) 11 is close to the hitting point and therefore has a large effect on spin performance. Therefore, by disposing the first hole H1 and the second hole H2 at the first end (tip portion) 11, the movement of the string 20 in the in-plane direction of the hitting surface can be secured, thereby improving spin performance.

[0044] Furthermore, the vertical strings 20 (main string portion 201) have a greater effect on spin performance than the horizontal strings 20 (cross string portion 202). Therefore, by arranging the first hole H1 and the second hole H2 at the second end (rear end) 12, the movement of the strings 20 in the in-plane direction of the ball hitting surface is ensured, thereby improving spin performance.

[0045] Also, the horizontal strings 20 (cross string portion 202) have a smaller effect on spin performance than the vertical strings 20 (main string portion 201), but they do affect spin performance. Therefore, by arranging the first hole H1 and the second hole H2 at the side end portion 13, the movement of the strings 20 in the in-plane direction of the ball hitting surface is ensured, thereby improving spin performance.

[0046] Also, by preventing the string 20 from hitting the inner surface of the through hole H of the racket frame 10, the appearance can be improved.

[0047] In addition, by preventing the string 20 from hitting the inner surface of the through hole H of the racket frame 10, damage to the grommet 15 and the string 20 can be reduced, thereby improving the durability of the grommet 15 and the string 20.

[0048] In the racket frame 10 according to this embodiment, the third hole H3 and the fourth hole H4 are inclined so that the distance between them decreases from the outer peripheral surface OS toward the inner peripheral surface IS. Therefore, when the third hole H3 and the fourth hole H4 are located on both sides of the folded-back portion 203, it is possible to prevent the string 20 from hitting the inner peripheral surface IS side of the inner circumference of the third hole H3 and the fourth hole H4. Therefore, by further preventing the string 20 from hitting the inner surface of the through-hole H of the racket frame 10, it is possible to further improve the spin performance.

[0049] In the racket frame 10 according to the present embodiment, the absolute value of the inclination angle of the first hole H1 with respect to the center line CL of the face portion 1 extending along the first direction D1 is equal to or less than the absolute value of the inclination angle of the second hole H2, and the absolute value of the inclination angle of the third hole H3 is equal to or less than the absolute value of the inclination angle of the fourth hole H4. The inventors have found that this effectively prevents the string 20 from hitting the inner surface of the through-hole H.

[0050] In the racket frame 10 according to the present embodiment, the absolute value of the inclination angle of the first hole H1 with respect to the center line CL is smaller than the absolute value of the inclination angle of the second hole H2, and the absolute value of the inclination angle of the third hole H3 is smaller than the absolute value of the inclination angle of the fourth hole H4. The inventors have found that this effectively prevents the string 20 from hitting the inner surface of the through-hole H.

[0051] In the racket frame 10 according to the present embodiment, the inclination angle of each of the first hole H1 and the third hole H3 is 2° or more and 4° or less in the counterclockwise direction, and the inclination angle of each of the second hole H2 and the fourth hole H4 is 3° or more and 5° or less in the clockwise direction. The inventors have found that this effectively prevents the string 20 from hitting the inner surface of the through-hole H.

[0052] The racket 100 according to this embodiment includes the above-mentioned racket frame 10 and strings 20 threaded through a plurality of through holes H. Therefore, the strings 20 are prevented from hitting the inner surfaces of the through holes H of the racket frame 10, thereby improving the spin performance.

[0053] (Example) Next, examples of the racket frame and racket according to the present embodiment will be described in comparison with comparative examples.

[0054] In this example, Examples 1 to 5 were compared with Comparative Examples 1 to 6 to verify the state in which the hitting surface was formed by stringing the string 20. Examples 1 to 5 have the same structure as the racket frame and racket according to the present embodiment. In Examples 1 to 5, the inclination angle of each of the first and third holes is 2° or more and 4° or less in the counterclockwise direction, and the inclination angle of each of the second and fourth holes is 3° or more and 5° or less in the clockwise direction.

[0055] In Comparative Example 1, the inclination angle of each of the first and third holes is 1° counterclockwise, and the inclination angle of each of the second and fourth holes is 1° clockwise. In Comparative Example 2, the inclination angle of each of the first and third holes is 5° counterclockwise, and the inclination angle of each of the second and fourth holes is 5° clockwise. In Comparative Example 3, the inclination angle of each of the first and third holes is 10° counterclockwise, and the inclination angle of each of the second and fourth holes is 10° clockwise.

[0056] In Comparative Example 4, the inclination angle of each of the first and third holes is 1° counterclockwise, and the inclination angle of each of the second and fourth holes is 1° clockwise. In Comparative Example 5, the inclination angle of each of the first and third holes is 5° counterclockwise, and the inclination angle of each of the second and fourth holes is 5° clockwise. In Comparative Example 6, the inclination angle of each of the first and third holes is 10° counterclockwise, and the inclination angle of each of the second and fourth holes is 10° clockwise.

[0057] In Example 1, the string material is polyester, the string diameter is 1.25mm, and the string tension is 50lbs. In Example 2, the string material is polyester, the string diameter is 1.25mm, and the string tension is 60lbs. In Example 3, the string material is polyester, the string diameter is 1.20mm, and the string tension is 50lbs. In Example 4, the string material is polyester, the string diameter is 1.20mm, and the string tension is 60lbs. In Example 5, the string material is nylon (multifilament), the string diameter is 1.30mm, and the string tension is 40lbs.

[0058] In Comparative Examples 1 to 3, the string material is polyester, the string diameter is 1.25 mm, and the string tension is 50 lbs. In Comparative Examples 4 to 6, the string material is polyester, the string diameter is 1.25 mm, and the string tension is 60 lbs.

[0059] In all of Comparative Examples 1 to 6, the strings hit the inner periphery of the inner surfaces of the first, second, third and fourth holes. In contrast, in all of Examples 1 to 5, the strings did not hit the inner periphery of the inner surfaces of the first, second, third and fourth holes. In addition, in all of Examples 1 to 5, the strings were located near the centers of the first, second, third and fourth holes on the side opposite to the folded-back portion.

[0060] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0061] 1 face portion, 2 shaft portion, 3 grip portion, 10 racket frame, 11 first end portion (tip portion), 13 side end portion, 20 string, 100 racket, CL center line, D1 first direction, D2 second direction, D3 third direction, H through hole, H1 first hole, H2 second hole, H3 third hole, H4 fourth hole, IS inner surface, OS outer surface.

Claims

1. A grip portion and A shaft portion connected to the grip portion; a face portion connected to the shaft portion, the face portion, the shaft portion, and the grip portion are arranged side by side in a first direction, the face portion includes an inner circumferential surface, an outer circumferential surface, a tip portion located on the opposite side to the grip portion in the first direction, a rear end portion located on the grip portion side in the first direction, and a side end portion located in a second direction perpendicular 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 disposed in at least one of the front end portion, the rear end portion, and the side end portion, and are inclined so that a distance between the first hole and the second hole decreases from the outer circumferential surface toward the inner circumferential surface, the plurality of through holes include a third hole and a fourth hole adjacent to each other, The third hole is disposed adjacent to the second hole, The fourth hole is disposed on an opposite side of the third hole from the second hole, the third hole and the fourth hole are disposed at the tip portion and are inclined so that a distance between them decreases from the outer circumferential surface to the inner circumferential surface, the first hole and the second hole are disposed in the tip portion, The second hole and the third hole are inclined so that the distance between them increases from the outer circumferential surface to the inner circumferential surface.

2. 2. The racket frame of claim 1, wherein an absolute value of an angle at which the first hole is inclined relative to a center line of the face portion extending along the first direction is less than or equal to an absolute value of an angle at which the second hole is inclined, and an absolute value of an angle at which the third hole is inclined is less than or equal to an absolute value of an angle at which the fourth hole is inclined.

3. 3. The racket frame of claim 2, wherein an absolute value of an angle at which the first hole is inclined relative to the center line is smaller than an absolute value of an angle at which the second hole is inclined, and an absolute value of an angle at which the third hole is inclined is smaller than an absolute value of an angle at which the fourth hole is inclined.

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

Images