JP2002035170A - Racket frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a racket frame which achieves excellent restitution characteristic in addition to excellence in lighter weight and operability and moreover secures a sufficient strength to hold gut spread with a higher tension. SOLUTION: An inner wall 12a of an outer shell layer 6 making up the side of an outer circumference portion 8 of a ball hitting part and a thin reinforcing rib 13 as link to bridge the inner wall 12a and an inner wall 12b of the outer shell layer 6 on the side of the inner circumference portion 9 facing the inner wall 12a are formed integrally in a hollow internal part of a tubular- structured outer layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket frame used for tennis (hereinafter, referred to as a racket frame).

[0002]

2. Description of the Related Art Conventionally, racket frames have been formed using materials such as wood and metal. However, at present, various characteristics such as toughness, rigidity and repulsion force required for racket frames are satisfied. In addition, since there is a large degree of freedom in designing such that a required shape can be easily obtained, a racket frame made of fiber reinforced resin has come to occupy the mainstream.

Usually, this type of racket frame 31 is
For example, as shown in FIG. 9 and FIG.
The shaft portion 33 and the grip portion 34 have a tubular structure composed of an outer shell layer 35 made of fiber reinforced resin. The hitting portion 32 of the racket frame 31 has an outer peripheral side surface 36, A number of gut insertion holes 38 are formed so as to penetrate the inner peripheral side surface 37. A gut protection groove 39 is formed in the outer peripheral side surface 36 of the hitting portion 32, and the gut protection groove 39 and each gut insertion hole 38 have the gut protection groove 3.
9, and a gut protection member 40 having a base and a tube fitted into the gut insertion hole 38 is mounted, and in the tube of the gut protection member 40, a gut 41 made of a material such as nylon, sheep, or whale muscle is provided. It is configured to be inserted to form a gut net surface.

A typical overall length L of this type of racket frame 31 is about 685 mm, the side width W of the frame in the direction orthogonal to the hitting surface is 20 mm to 23 mm, and the frame in the direction orthogonal to the side width W. Front width T is approximately 1
It is in the range of 2 mm to 15 mm, the mass before the gut is stretched is about 270 g to 330 g, and the moment of inertia in the swing direction around the point P, which is 80 mm from the grip end 42, as the rotation axis is 0.035 kg · m ² -0.03
Almost 7 kg · m ² .

In recent years, racket frames 3
In order to improve the operability of (1), weight reduction is required. Particularly, relatively weak players such as women, children, and elderly players have a strong demand. In addition to such light weight and good operability, there is also a demand for an improvement in resilience performance for improving the flight of a ball when hit. That is, a lightweight racket frame excellent in resilience performance is required. However, from the viewpoint of the collision between the racket frame and the ball, when the mass of the racket frame 31 is reduced based on the principle of energy conservation, the resilience performance of the ball tends to decrease. That is, as the weight of the racket frame is reduced, the resilience performance is reduced.

In view of these problems, various studies have been made to improve the resilience performance when hitting a ball, and in recent years, so-called "mode analysis" has been attempted.
A proposal for improving the resilience performance of a ball at the time of a hit by designing the racket frame with a higher natural frequency has been spotlighted.

[0007] For example, Japanese Patent Application Laid-Open No.
No. 0881, as shown in FIGS. 11 (a) and 11 (b),
Connect the frame body to the frame
3, a shaft portion 45 including a throat portion 44 extending on an axis in the longitudinal direction from the frame string portion 43, and a grip portion 4 extended and formed on the distal end side of the shaft portion 45.
6, the thickness Wa of the throat portion 44 is made larger than the thickness Wb of the grip portion 46 so that the natural frequency of the frame main body can be increased by the ball. Racket frames have been proposed and are known which are configured to correspond approximately to the time during which they are in contact with the surface, thereby enhancing the resilience characteristics of the ball.

[0008]

In this type of racket frame 47, the second moment of area of the frame is about 3 to about 2 times smaller than the second moment of area of the standard racket frame.
A racket frame having a so-called "thick racket" structure that is formed to be approximately four times as large is provided with a means for increasing the natural frequency of the frame, whereby the vibration energy of the racket frame 47 at the time of impact is reduced. Since it can be made to work effectively for acceleration promotion,
The rebound characteristics and directionality of the ball at the time of impact can be improved to a satisfactory level.

However, in this type of racket frame, as shown in FIG. 12A, the second moment of area of the frame is much larger than the second moment of area of the standard racket shown in FIG. 12B. Due to the formation, the cross-sectional circumferential length of the frame is increased by that amount, and the mass ratio occupied by the outer shell layer 48 constituting the racket frame tends to increase. Therefore, in the racket frame 47 in which the second moment of area is enlarged in this way, when designing on the assumption that a lightweight racket frame is obtained, in order to avoid an increase in the mass of the racket frame,
Thickness N of outer shell layer 48 compared to standard racket frame
Has a structural restriction that it must be relatively thin. As a result, the strength of the frame is relatively insufficient, and particularly, the hitting portion (the frame string portion 4)
In 3), as shown in FIG. 13, when the gut is stretched, the portion between the gut insertion holes 38 to which excessive stress concentration is applied from the gut 41 and the peripheral region Q of the gut insertion hole are easily crushed. There was a problem such as being damaged due to being damaged.

Therefore, in the above-mentioned region, it is required to make the thickness N of the outer shell layer 48 constituting the region large in order to maintain the strength of the frame when the gut is stretched. However, it has not been possible to further reduce the weight of the racket frame while securing a practically sufficient strength of the racket frame.

As described above, conventionally, the required characteristics of reducing the weight of the racket frame, improving the resilience performance, and further ensuring the required strength of the racket frame conflict with each other. It is now difficult to obtain a racket frame that has a design configuration and can sufficiently satisfy all of these requirements.

In view of the above problems, the present invention holds a gut which is excellent in resilience characteristics and high in tension while being a lightweight racket frame excellent in operability. It is an object of the present invention to provide a racket frame capable of securing sufficient strength.

[0013]

In order to achieve the above object, the present invention has the following arrangement. That is, the racket frame according to claim 1 of the present invention has a frame mass before gut stretching in the range of 230 g to 280 g, and the side surface width of the frame in a direction orthogonal to the hitting surface is 30 m.
In a racket frame made of fiber reinforced resin set in a range of m to 45 mm, the racket frame has a cross section cut in a direction perpendicular to the hitting surface, a hollow inside of an outer shell layer having a tubular structure, It is characterized in that a thin reinforcing rib for bridging and connecting the inner wall of the outer shell layer forming the outer peripheral side surface and the inner wall of the outer shell layer on the inner peripheral side surface facing the inner wall is integrally formed. It is assumed that.

According to a second aspect of the present invention, there is provided the racket frame according to the first aspect, wherein a length between the opposing inner walls of the reinforcing rib is 0.1 mm or less in a region constituting the hitting portion.
It is characterized in that it is set within a range of 5.0 mm.

According to a third aspect of the present invention, there is provided the racket frame according to the first or second aspect, wherein the thickness of the reinforcing rib is equal to 0.1.
The distance is set within a range of 2 mm to 2.0 mm.

A fourth aspect of the present invention is the racket frame according to the first, second, or third aspect, wherein a cross-sectional ratio (reinforcement) of the outer shell layer and the reinforcing rib in a cross section cut in a direction orthogonal to the hitting surface is provided. Rib / outer shell layer) is set in the range of 20% to 80%.

Claim 5 is the above-mentioned claim 1, 2, 3 or
4. The racket frame according to 4, wherein a ratio of a side width of the racket frame to a frame front width in a direction orthogonal to the side width (side width / front width) is set to 2.0 to 4.0. It is characterized by having.

According to a sixth aspect of the present invention, there is provided the racket frame according to the first, second, third, fourth, or fifth aspect, wherein a moment of inertia in a swing direction is set at a position 80 mm from a grip end portion of the racket frame as a rotation axis. Is 0.032k
It is characterized by being designed to be g · m ^{2 to} 0.035 kg · m ² .

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing the front and side surfaces of the racket frame of the present embodiment, and FIG.
FIG. 3 is a cross-sectional view taken along the line BB of FIG. 1, and FIG. 4 is an explanatory view showing the configuration of the frame in the AA line region.

That is, the racket frame 1 of this embodiment is
As shown in FIG. 1, a hitting portion 3 in which a gut 2 is stretched to form a hitting surface, and a shaft portion 5 connecting the hitting portion 3 and a grip portion 4 are formed of an outer shell layer 6 made of fiber-reinforced resin. Has a tubular structure composed of The overall length L of the racket frame 1 is 705 mm, and the side surface width W of the frame in a direction orthogonal to the hitting surface is 30 mm in the entire area of the hitting portion 3 excluding the grip portion 4 of the racket frame 1 and the shaft portion 4. The racket frame has a so-called “thick racket” structure designed within a range of up to 45 mm. The portion having the maximum width W1 of the side surface width W of the frame is 0.6 L or more of the total length L of the racket frame 1 from the grip end portion 7.
0.5L and its maximum width W1 is 35
mm to 45 mm. As shown in FIG. 1, the width of the portion from the portion having the maximum width W1 to the tip portion side of the hitting portion 3 and the grip portion 4 side of the shaft portion 5 is configured to be gradually reduced. The shaft 3 has a width of 30 mm to 36 mm (W2) on the tip side, and the shaft 5 has a width of 30 mm to 36 mm (W3) on the grip 4 side.

The front width T of the frame in a direction orthogonal to the side width W is designed to be approximately in a range of 12 mm to 15 mm, and is a ratio to the side width W of the frame (side width / front width). Is designed to be in the range of 2.0 to 4.0.

In the present embodiment, by designing such a racket frame shape, the out-of-plane primary natural frequency of the racket frame 1 is set to 200 Hz to 300 Hz while setting the bending rigidity of the frame to be high, so that the Is formed so that a high resilience performance can be obtained by eliminating the energy loss.

In the racket frame 1 of the present embodiment,
As shown in FIG. 2, the thickness N of the outer shell layer 6 constituting the racket frame 1 is made as thin as about 0.5 mm to 1.5 mm so that the mass of the racket frame 1 can be reduced. The racket frame 1 has a lightweight structure in which the weight of the racket frame 1 is in the range of 230 g to 280 g, particularly in the range of 230 g to 270 g before the gut is stretched.
The moment of inertia in the swinging direction about the point 80 mm from the grip end 7 is 0.032 kg · m.
It is set in the range of ^{2 to} 0.035 kg · m ² . By setting the racket frame 1 to a light weight and setting the moment of inertia within the small range as described above, a racket that is easy to swing even for a woman, a child, an aged player, or the like, and has good operability. Frame 1
Becomes

FIGS. 2 to 4 show the configuration of the hitting portion 3 of the racket frame 1 according to the present embodiment. The hitting portion 3 has a hollow tubular structure formed by an outer shell layer 6 made of fiber reinforced resin.
A number of gut insertion holes 10 are formed at an arbitrary interval in the circumferential direction so as to penetrate the outer peripheral side surface 8 and the inner peripheral side surface 9, and a gut protection groove is formed on the outer peripheral side surface 8 side. 11 is recessed. In the present embodiment, with the thickness N of the outer shell layer 6 being reduced, in the conventional racket frame, a portion between the gut insertion holes 10 or around the gut insertion hole 10 is formed by stretching the gut 2. Although there was a problem that the area was damaged,
The outer peripheral side surface 8 of the hitting portion 3 is provided inside the hollow of the outer shell layer 6.
The inner wall 12a of the outer shell layer 6 constituting the inner wall 12a and the inner wall 12b of the outer shell layer 6 on the side of the inner peripheral side 9 facing the inner wall 12a are integrally formed with the thin reinforcing ribs 13 to form a bridge. Even if the outer shell layer 6 has a thin structure, the outer shell layer 6 is configured to have sufficient strength to hold the gut 2 stretched with high tension.

That is, in the hollow inside of the outer shell layer 6 having a tubular structure, each of the outer shell layer 6 forming the outer peripheral side surface 8 side and the outer shell layer 6 forming the inner peripheral side surface 9 side of the hitting portion 3 is provided. Inner wall 12
a, a thin reinforcing rib 13 for bridging and connecting the 12b to each other
Is formed integrally, the stress from the gut 2 applied to the frame when the gut is stretched is received by both the outer shell layer 6 on the outer peripheral side surface 8 side and the outer shell layer 6 on the inner peripheral side surface 9 side. Become like Therefore, the racket frame 1 of the present embodiment
In this case, the outer shell layer 6 on the outer peripheral side surface 8 side and the outer shell layer 6 on the inner peripheral side surface 9 side are formed in the above-described region, though the thickness N of the outer shell layer 6 is generally reduced. The combined characteristics of both strength and rigidity can be expressed, and while being lightweight,
It is possible to obtain sufficient strength to hold the gut 2 stretched with high tension.

The shape and size of the reinforcing ribs 13 are variously different depending on the mass of the racket frame 1 itself, the thickness N of the outer shell layer 6, and the cross-sectional shape of the frame. As a result of conducting many experimental studies in consideration of the relationship between strength and mass on the premise of obtaining a lighter racket frame 1 while exhibiting practically sufficient strength, the inner wall of the reinforcing rib 13 opposed to the reinforcing rib 13 was obtained. The length R between 12a and 12b is 0.1 mm to 5.0.
mm, particularly preferably in the range of 1.0 mm to 3.0 mm. When the length R is smaller than 0.1 mm, the front width T of the hitting portion 3 must be designed to be extremely small, and the rigidity of the hitting portion 3 in the in-plane direction is reduced, so that the hitting ball is hit. There is a risk that the surface may not be stable. The length R is
If it is larger than 5.0 mm, the mass of the reinforcing rib 13 itself is increased in the racket frame 1, and there is a problem that the operability of the racket frame 1 is adversely affected.

The width S of the reinforcing rib 13 is as follows.
It is preferable that the distance be set in the range of 0.2 mm to 2.0 mm. When the width S is smaller than 0.2 mm,
Necessary strength development cannot be expected, and the width S is 2.0 m
When it is larger than m, there is a problem that the mass of the racket frame increases, which adversely affects operability. As a result of specifying the suitable range of the length R and the width S of the reinforcing rib 13, the reinforcing rib 13 has a shape corresponding to the cross section of the outer shell layer 6 cut in a direction orthogonal to the hitting surface.
3 cross section ratio (reinforcement rib / outer shell layer) is 20% to 80%
Is more desirably set within the range.

As a means for designing the length R of the reinforcing rib 13 within the range of 0.1 mm to 5.0 mm as described above, the cross-sectional shape of the frame as in the configuration of the above-described embodiment is used. In a flat shape such that the side width W / the front width T is in the range of 2.0 to 4.0,
6A, a concave groove 14 is provided on the inner peripheral side surface 9 side of the frame, as shown in FIG. 6A, so that the outer shell layer in a region constituting the concave groove 14 is formed. 6 is moved to the inner wall 12a side of the gut protection groove 11 on the outer peripheral side surface 8 side, and the inner walls 12a, 12b
The distance R between the reinforcing ribs 13 can be set to be within the above range by reducing the distance between the reinforcing ribs 13. Further, as shown in FIG. The inner wall 12a of the gut protection groove 11 is replaced with an inner wall 12b on the inner peripheral side surface 9 side.
The length R of the reinforcing rib 13 can be set within the range by reducing the distance between the inner walls 12a and 12b. Incidentally, in the above configuration, in the configuration in which the concave groove 14 is provided on the inner peripheral side surface 9 side of the frame, the displacement supporting point of the gut after the gut is stretched is compared with the racket frame without the concave groove 14. Outer side surface 8
Since it can be shifted to the side, it is more preferable because the racket frame 1 of the same size and shape can realize the enlargement of the sweet spot surface without enlarging the outer shape of the hitting portion 3. is there.

The racket frame 1 of the present embodiment as described above
In order to manufacture, for example, a plurality of prepreg sheets 16 for racket frame molding are laminated and wound around a tube 15 for internal pressure molding, and after arranging them in a cavity having a mold frame shape, In a normal method of manufacturing a racket frame made of fiber reinforced resin, in which compressed air or the like is injected into the tube 15 and heated, first, a plurality of prepreg sheets 16 are stacked and wound around the tube 15 in advance as shown in FIG. Spun frame molding material 1
7 are prepared, and are stacked and arranged in a direction orthogonal to the hitting surface. Next, the two superimposed as described above
A plurality of prepreg sheets 16 are laminated and wound around the frame forming materials 17, 17 to form a racket frame formed body 18, which is then loaded into a cavity of a mold, and heated. Means are formed by pressing.

As the main reinforcing fibers constituting the racket frame 1 made of the fiber-reinforced resin of the present embodiment, various types such as carbon fiber, glass fiber, boron fiber and aromatic polyamide fiber can be used. Carbon fibers are also preferable in terms of mass and cost. As the matrix resin, epoxy resin, nylon resin, etc. can be used,
Epoxy resins are preferred in terms of strength and durability.

The racket frame 1 of the present invention is not limited to the configuration of the above-described embodiment. For example, in the above-described embodiment, as the configuration of the reinforcing rib 13, the outer shell layer 6 on the outer peripheral side surface 8 side of the frame is used. Although a configuration in which one reinforcing rib 13 is provided to bridge and connect the outer shell layer 6 on the inner peripheral side surface 9 side has been described, a configuration in which two or more reinforcing ribs 13 are provided may be employed. Further, in consideration of the workability of drilling the gut insertion hole 10 and preventing the strength of the reinforcement rib 13 from being reduced by the drilling of the gut insertion hole 10, as shown in FIG. To the neutral axis M, eg ABS
Light and good formability plate material 19 of resin, polyamide resin, etc.
Can be buried.

[0032]

EXAMPLES In order to confirm the effects of the present invention, the following Table 1 was used.
The racket frames of Example 1 and Comparative Examples 1 to 3 shown in FIG.

[0033]

[Table 1]

That is, the racket frame 1 facilitated as the first embodiment has a “thick racket” structure in which the side surface width W of the frame is set in the range of 30 mm to 45 mm as in the above-described embodiment. As shown in FIG. 2, the outer shell layer 6 has a thickness N of 0.5 mm to 1.5 mm, and the outer peripheral side surface 8 and the inner peripheral side surface 9 of the frame are provided inside the hollow of the outer shell layer 6 having a tubular structure. A racket frame 1 having a structure integrally provided with reinforcing ribs 13 for bridging and connecting the sides was prepared. still,
The length R of the reinforcing rib was set in a range of 1.0 mm to 3.0 mm, and the width S was set in a range of 0.2 mm to 2.0 mm.

As Comparative Example 1, a racket frame having the above-mentioned structure without the reinforcing rib 13 was prepared. Other configurations of the racket frame of Comparative Example 1 were substantially the same as those of the racket frame 1 of Example 1 described above, and the weight of the racket frame was 255 g because the reinforcing ribs 13 were not provided.

As Comparative Example 2, the above Comparative Example 1 was used.
Similarly to the above, the racket frame is not provided with the reinforcing rib 13, and the thickness N of the outer shell layer 6 is set to 1.0 mm to 1.5 m.
m and a thicker one were prepared.

As a comparative example 3, a racket frame in which the side width W is set within the range of 23 mm to 26 mm without using the “thick rake” structure as in the above-described example 1 and the comparative examples 1 and 2 is used. And the thickness N of the outer shell layer 6 is 1.0 mm
When the mass of the frame is in the range of
A racket frame set to 260 g was prepared in the same manner as in the above. Note that the racket frame of Comparative Example 3 did not have the reinforcing ribs 13 as in Comparative Examples 1 and 2.

The racket frames of Example 1 and Comparative Examples 1 to 3 were subjected to the following strength tests in order to confirm the strength of the frames when the gut was stretched. That is, as shown in FIG. 8, a wire 20 having a diameter of 1.6 mm is provided between adjacent gut insertion holes 10 of the racket frame 1.
When the wire 20 is chucked at both ends and a tensile load is applied by the load cell 21, the outer shell layer forming the folded portion of the wire 20, that is, the portion between the gut insertion holes 10 of the racket frame 1. The load when 6 was collapsed or broken was measured. The measurement results at this time are shown in Table 2 below.
Shown in

[0039]

[Table 2]

Further, in addition to the above test, an actual hit test was performed on these racket frames. In this live hit test, among general amateur players, especially women, children and elderly players,
The ball was hit with the racket frames of Example 1 and Comparative Examples 1 to 3, and at that time, the operability (easiness of swinging) of the racket frame felt by the player and the resilience performance at the time of hitting were evaluated. The test results at this time are shown in Table 3 below.

[0041]

[Table 3]

From Tables 2 and 3, it can be seen that the racket frame 1 of the first embodiment has characteristics, such as operability and resilience upon impact, and strength of the frame, as compared with the racket frames of Comparative Examples 1 to 3. It was confirmed that excellent effects were obtained in both cases.

[0043]

As described above, the racket frame of the present invention is lightweight and has a lateral width of 30 mm.
Since it is a racket frame with a lightweight thick racket structure set within the range of ~ 45 mm, it is excellent in operability even for relatively weak players such as women and children, and even elderly players, and when hitting Good resilience characteristics can be obtained.

Further, in the present invention, the hitting portion is configured such that the inner wall of the outer shell layer forming the outer peripheral side of the frame and the inner peripheral side facing the inner wall are provided inside the hollow of the outer shell layer having the tubular structure. Since the thin reinforcing ribs are provided integrally to bridge and connect the inner wall of the outer shell layer on the side, the strength of the frame, which decreases with the weight reduction of the racket frame, can be sufficiently compensated. Things. In particular, in the present invention,
With the above-described configuration, the strength required for the racket frame can be sufficiently secured, so that the thickness of the outer shell layer can be made smaller than that of the conventional racket frame. As a result, the weight of the racket frame can be further reduced. Can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the front and side surfaces of a racket frame according to the present embodiment.

FIG. 2 is an end view taken along the line AA of FIG. 1;

FIG. 3 is a sectional view taken along the line BB of FIG. 1;

FIG. 4 is an explanatory diagram of a configuration of a frame in an AA line part region of FIG. 1;

FIG. 5 is an explanatory view illustrating a method of manufacturing the racket frame according to the embodiment.

FIG. 6 is an explanatory diagram showing another embodiment.

FIG. 7 is an explanatory diagram showing another embodiment.

FIG. 8 is an explanatory diagram showing a test method.

FIG. 9 is an explanatory view showing the front and side surfaces of a conventional racket frame.

FIG. 10 is an explanatory diagram of a configuration of a frame in a line CC region of FIG. 9;

FIG. 11 is an explanatory view showing a conventional racket frame.

FIG. 12 is an explanatory view showing a conventional racket frame.

FIG. 13 is an explanatory view showing a conventional racket frame.

[Explanation of symbols]

 Reference Signs List 1 racket frame 2 gut 3 hitting portion 4 grip portion 5 shaft portion 6 outer shell layer 7 grip end portion 8 outer peripheral side surface 9 inner peripheral side surface 10 gut insertion hole 11 gut protection groove 12a inner wall 12b inner wall 13 reinforcing rib 14 concave groove 15 tube 16 Pre-preg sheet 17 Frame molding material 18 Racket frame molded body 19 Plate material 20 Wire 21 Load cell 31 Racket frame 32 Hitting portion 33 Shaft portion 34 Grip portion 35 Outer shell layer 36 Outer side surface 37 Inner side surface 38 Gut insertion hole 39 Gut protection groove 40 Gut protection member 41 Gut 42 Grip end part 43 Frame tension part 44 Throat part 45 Shaft part 46 Grip part 47 Racket frame 48 Outer shell layer

Claims (6)

[Claims] 1. Frame weight before gut stretching is 230 g
280 g, and the side surface width of the frame in the direction perpendicular to the hitting surface is set in the range of 30 mm to 45 mm. In the racket frame made of fiber reinforced resin, the racket frame is perpendicular to the hitting surface. In the cross section cut in the direction in which the outer shell layer has a tubular structure, the inner wall of the outer shell layer forming the outer peripheral side surface of the frame and the inner wall of the outer shell layer on the inner peripheral side surface facing the inner wall are formed. A racket frame having a structure in which a thin reinforcing rib for bridging and connecting the two is integrally formed. 2. A length between opposing inner walls of the reinforcing rib is 0.1 mm to 5.0 mm in a region constituting a hitting portion.
2. The racket frame according to claim 1, wherein the range is set within the range. 3. The reinforcing rib has a thickness of 0.2 mm to 2.
3. The racket frame according to claim 1, wherein the racket frame is set within a range of 0 mm. 4. A cross-sectional ratio (reinforcement rib / outer shell layer) between the outer shell layer and the reinforcing rib in a cross section cut in a direction orthogonal to the ball striking face is set within a range of 20 to 80%. The racket frame according to claim 1, 2 or 3, wherein: 5. The ratio of the side width of the racket frame to the front width of the frame in a direction orthogonal to the side width (side width / side width).
The racket frame according to claim 1, 2, 3, or 4, wherein the front width is set to 2.0 to 4.0. 6. The swing moment of inertia about a point 80 mm from the grip end of the racket frame as a rotation axis is 0.032 kg · m ^{2 to} 0.035 kg.
· Claim 1, characterized in that it is designed in m ^2,
The racket frame according to 2, 3, 4, or 5.