JPH01297086A - Racket frame - Google Patents

Abstract

PURPOSE:To obtain a racket frame with a little vibration and impact even when a ball hitting is executed in dislocation from an impact center by causing the back width of a frame part to support a longest longitudinal gut and a longest lateral gut to be small, composing a part whose back width is made large between them, and gradually increasing and decreasing the space between the frame parts of the back widths. CONSTITUTION:A top 5 and a yoke 7 are made into the minimum back widths as the frame parts to support a longitudinal gut 8, and the top 5 and yoke 7 are formed with an HP(hyperbolic parabolic) curved surface and an EP(elliptic parabolic) curved surface, respectively. The back width dimension is formed to be maximum in respective line parts of frame parts B, B, D and D at four points in the approximately intermediate respective parts of the top 5 and sides 6 and 6 and the yoke 7 and sides 6 and 6. The space between the minimum part and maximum part of the frame back width is formed in the curved surface to be smooth in which the back width is gradually increased and decreased, and even the section of a shaft part 3 from a yoke part 2 up to a grip 4 edge is made to gently correspond the thickness of the grip part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a racket frame used for tennis, badminton, etc.

(Prior art) Generally, tennis rackets, badminton rackets, etc. have a racket frame that is made of a material such as FRP and is integrated with the face, yoke, and shaft (including the grip).
It is constructed by molding, forming a large number of gutt holes in this oblong face portion, and tightening the gutts into the gutt holes.

The repulsive action of this racket when hitting a ball, etc. is due to the repulsive force (spring j1) of the guts stretched on the face, but the repulsive force of the guts is mainly caused by the elasticity of the guts, the elasticity around the hole that supports the guts, and the face. It is known that the elasticity of the frame of the section and the elasticity of the shaft section depend on three spring elements. Since these three spring elements are connected in series, unless they have equal strength,
The weakest spring will be the main force in repulsion, and this will determine the repulsion of the racket.

The three factors that determine the elasticity of these rackets are described below.

(b) The guts stretched on the face part have warp threads and
As weft threads, each thread is usually strung consecutively. For that reason,
Both the warp and the weft have the longest strings in the center (centerline) and become shorter toward the ends.

Although the tension of these strings can be differentiated between the warp and weft, the strings in one direction are almost constant in one racket frame.

The elasticity of the gut (the strength of the spring) depends on its tension and length, if the material is the same thickness. That is, if the tension is constant, it is inversely proportional to the length. Generally, in the case of a racket frame, if the length of the central part in the major axis direction and the minor axis direction is l, the length of each end is approximately 0.6, so the spring force of the end guts is It is 1.67 times the spring force of Gatsuto.

(U) Furthermore, the holes that support the guts are formed in a line in the width direction of the face portion.

The elasticity around these holes becomes a very stiff spring as long as it is based on the deformation of the grommet, and unless the face and shaft parts have very high rigidity, they have the property of not functioning as a spring. Therefore, when considering the repulsive force of a racket, the elasticity around the string hole is usually not taken into account.

(8) Furthermore, the elasticity of the frame of the face is influenced by the size and shape of the oval, the rigidity of the material, etc.1, and these factors affect the racket's weight, quality distribution, swing balance, etc. It is determined based on the assumption that the value is within the target range.

In the past, the oval shape of the face part was usually formed by a frame with equal back width and thickness all around. The cross-sectional circumference of this face frame is approximately 60 to 70 mm in relation to the weight of the racket frame, but the ratio of thickness (b) to back width (h) is approximately 1:1.5 to 2. (See Figure 20).

The deformation of such a conventional racket frame when hitting a ball is
This is the deformation mode of the rod, and the deformation of the frame of the face part is deformed into a spoon shape as shown in FIG. Its bending rigidity is defined by the product EI of the second moment of area I and the elastic modulus E. In addition, the spring that supports the gut mainly deforms the grommet and hardly contributes to repulsion, but plays a larger role in absorbing shock.

In recent years, various shapes have been tried for the side shape of the face portion, that is, the back shape, with the aim of improving repulsion performance. For example, there are known shapes in which the back width of the portion of the face portion closer to the yoke is larger, or the shape where the back width dimension is larger at the sides (left and right center portions) of the face portion.

(Problem to be solved by this invention) In tennis, badminton, etc., when a ball is hit with the center of impact (center of impact, sweet spot) off, an undesirable shock and vibration is applied to the arm, and this repetition causes damage to the tennis ball. It is known to cause tennis elbow.

Eliminating this shock and vibration has been a long-standing challenge in manufacturing racket frames using high-strength composite materials (high rigidity).

If the rigidity of the frame is lowered to soften the impact when the ball is hit off the sweet spot, the resulting frame vibration will be slow to dampen, leaving the player feeling uncomfortable in the hand. On the other hand, if the frame rigidity is increased, vibration damping will be faster, but the impact will be felt more strongly. These two conflicting problems could not be solved by considering only frame rigidity.

Another reason for this shock and vibration is that the face frame of tennis rackets, etc., is oval in shape, and the strings are stretched vertically and horizontally in the major and minor diameter directions, going from the center to the ends. However, since the tension of these guts is almost the same, the repulsive force (spring force) of the guts becomes stronger toward the ends.

For this reason, when the ball is hit with the edge of the racket away from the center of impact, the deflection of the gut is small, and the impact is felt more in the hand than when the ball is hit at the sweet spot.

Making the deflection of these guts equal over the entire face is a desirable structure for players to soften the impact of the ball.

To do this, for example, it is possible to change the tension of the strings depending on the length, but the strings used in general rackets such as tennis rackets have strings in the major axis direction (warp threads) and short axis strings (weft threads). ), each of which is mechanically stretched vertically and horizontally, which would be impossible in reality, and even if it were possible, there would be problems that would make it impractical.

This invention reduces vibration and impact even with a highly rigid frame by changing the cross-sectional shape of the racket frame that supports the strings without changing the tension of the strings depending on the length, and provides good repulsion performance. The purpose is to obtain a racket frame.

In other words, by making the part of the frame that supports the short guts more deformable than the part of the frame that supports the longer guts, and by supporting the shorter guts with softer springs than the parts that support the longer guts, the ball was hit off the center of impact. The objective is to obtain a racket frame with very little vibration and impact compared to conventional racket frames.

(Means for solving the problem) In order to achieve this purpose, among the strings that are stretched on the face of the racket frame, a frame portion that supports the shorter strings of the strings that are stretched in the same direction. The structure is such that it is easier to deform than the frame part that supports the long gut.

More specifically, the back widths of the mutually opposing frame portions supporting the longest vertical gut of the face portion constituting the racket frame and the mutually opposing frame portions supporting the longest horizontal guts are configured to be small, and these frames A frame part with a large back width is formed between the parts, and a frame part with a back width that gradually increases or decreases between the frame part with a large back width and the frame part with a small back width.

In addition, in a racket frame in which the back width of the face portion that constitutes the racket frame is constant and the outer peripheral surface is curved, the frame portions that support the longest vertical gutt of the face portion and the longest horizontal gutts are arranged opposite to each other. It consists of frame parts with a small radius of curvature of the straight cut cross section (cut surface perpendicular to the central axis of the frame) of the outer peripheral curved surface of the supporting frame parts facing each other, and the straight cut surface of the outer peripheral curved surface of the frame is formed between these frame parts. A frame that has a frame portion with a large radius of curvature on the cut surface curve, and the outer circumferential curved surface is formed with a radius of curvature that gradually increases or decreases between the frame portions with the large and small curvature radius of the straight cut section of the frame outer circumferential curved surface. Even if it is composed of parts, it has the same function and effect.

Furthermore, the radius of curvature of the straight-cut cross section of the back width and outer circumferential curved surface of the mutually opposing frame portions that support the longest vertical string of the face portion that make up the racket frame, and the mutually opposing frame portions that support the longest horizontal string of the racket frame has been reduced. between these frame parts, a frame part with a large radius of curvature of the straight cut section of the outer peripheral curved surface is constructed; The same effect can be obtained by using frame portions formed by a back width and a radius of curvature that gradually increases or decreases between frame portions having a small radius.

(Effect) If you put a lot of effort into a face frame with this shape,
The longer the length and width of each gutt, the smaller the back width of the face frame part, the radius of curvature of the cut section of the outer peripheral curved surface, or both are smaller. The radius of curvature of the back of the face frame or the straight cut section of the outer circumferential curved surface is large and smooth.

The repulsion springs of a racket can be roughly divided into three types: springs for the guts, springs for the part that supports the guts, and springs for the face frame and shaft.

These springs are connected in series, so if the frame and shaft have high rigidity, the two main sources of repulsion will be the gut spring and the spring in the part that supports the gut.

If the material, cross-sectional area, and tension of Guttu springs are the same, the spring depends only on the length.

In addition, unlike conventional frames, the frame spring that supports the gutt is not easily deformed due to the deformation of the rod, but the main deformation is the curved surface (shell) that makes up the outer periphery of the frame, and the deformation of this curved surface can be restored. Force becomes the main force in repulsion.

This deformation of the curved surface of the frame outer periphery is caused by wall thickness (1), material (
Young's modulus E), radius of curvature (a), and back sling (Harima) (
Depends on h). Therefore, the material (Young's modulus E) and wall thickness (
If 1) is the same, the back width (h) or the radius of curvature (a)
Depends on. With respect to a concentrated load on the frame face surface, the deformation of the outer peripheral curved surface of the frame is proportional to the cube of the back width or the cube of the radius of curvature, and the resulting spring force is inversely proportional. Therefore, due to the combination of the springs of the gut due to the difference in length and the hardness and softness of the spring supporting the gut due to the difference in the frame back width or the frame outer circumferential curvature radius, the repulsion when hitting a ball is approximately equal for the entire face surface. - The racket frame when hitting a ball is different from a conventional racket frame in that the frame hardly deforms in the same manner as the rod deforms, and only flexes in the gut (see Fig. 19). Therefore, less vibration occurs, shock is absorbed, and the entire face
They have the same spring characteristics.

(Example) The present invention will be described based on drawings showing embodiments.

1 to 7 show a tennis racket according to an embodiment in which the dimensions of the back width are changed and the outer circumferential surface is mainly formed of a HP curved surface, and FIG. 1 shows the plane (gut surface) of the tennis racket, Figure 2 shows the front of the tennis racket. 3 to 7 are A, 81C, and D of FIG. 1, respectively.

The cross-sectional shape of the face frame portion taken along line E is shown.

8 to 14 show other embodiments of a tennis racket in which the dimensions of the back width are changed and the outer peripheral surface is formed with an EP curved surface. FIG. 8 shows a plan view, and FIG. 9 shows a front view. 10 to 14 show cross-sectional shapes of the face frame section taken along lines F, G, H, I, and J in FIG. 8.

The names used for these face frames are defined in the first section.
As shown in FIGS. 5 and 16, the process is as follows.

The back width (h) is the frame thickness dimension in the direction perpendicular to the face surface, the thickness (b) is the frame thickness dimension in the same direction as the face surface, and the wall thickness (1) is the thickness dimension of the cylindrical wall forming the frame.
The radius of curvature (a) is the radius of a directly cut section of the outer peripheral surface of the frame.

(X) shows the outer peripheral surface side of the face frame, and (Y) shows the inner peripheral surface side of the face frame.

Tennis rackets are made of fiber-reinforced composite materials such as CFRP, high-strength (high-rigidity) composite materials such as metal, aluminum alloy, and other moldable materials, and include a face portion (1) consisting of an oval frame, and a grip. Shaft part (3) including part (4), face part (1) and shaft part (3)
The yoke part (2) is a continuous part between the two parts.

In the face portion (1), (5) indicates the top, (6) the side, and (7) the yoke. That is, the oval face part (1) has a top (5) at both ends of the vertical center line, which is the center line in the major axis direction, and a yoke (force) at the proximal side. The parts on both sides of the horizontal center line, which is the center line of the direction, are the left and right sides (6), (6).Several vertical guts (8) and horizontal guts ( 9).

The frame of the face part (1) supports the longest vertical gut (8) between the parts that face each other in the center line in the long diameter direction, that is, the top (5) part and the yoke (7) part, and The longest horizontal gut (9) is supported between the parts facing each other in the line, that is, both sides (6), (6) parts.

In the racket frames shown in Figures 1 to 7, the wall thickness (t) and material (Young's modulus E) of the face frame are constant, the radius of curvature (a) is also constant over most of the frame, and the back width is This is a configuration in which (h) is changed. The radius of curvature (a) consists of a nearly constant HP curved surface with a radius of curvature (a) of -18mn<O in the parts other than the yoke (7) part, and the radius of curvature (a) is only near the yoke (force part).
This is an example consisting of an EP curved surface of >O.

In this example, the maximum weight of the racket with guts is 340g~
Since the racket weighs about 360g, the face part (1)
The maximum circumferential length of the cross section of the frame is around 60 to 70 mm, and the maximum wall thickness (1) is about 1 mm (8 braises). Since the wall thickness (t) is small, the cross-sectional shape of the frame of the face part (1), except for the yoke (7), is a shape that is less likely to buckle, in terms of an inverted arch shape or a curved shape.
A hyperbolic parabolic surface (f
(P curved surface), mainly the back width (h)
By changing the strength of Gatsuto's support spring.

That is, the top (5) supporting the longest vertical gut (8)
), each part of the yoke (7), each part of both sides (6), (6) supporting the longest horizontal gutt (9), supports the shorter vertical gutt (8) and horizontal gutt (9). The back width (h) is formed to be relatively smaller than the supporting portion.

Therefore, the top (5) and yoke (force is
8) It becomes an extremely small back sling as a frame part that supports
In this embodiment, each is formed to 25IIlff+.

As for the outer circumferential surface, the top (5) is formed of an HP curved surface as shown in FIG. 3, and the yoke (7) is formed of an EP curved surface as shown in FIG. 7, but the entire surface may be formed of a HP curved surface. Also, both sides (6), (6) are frame portions that support the horizontal guts (9) and have an extremely small back width of 2811IIm, and the outer peripheral surfaces are HP curved surfaces.

These four frame parts B, B, D, and D are approximately in the middle of each of the top (5) and sides (6), (6), and the yoke (7) and sides (6), (6). The back width dimension is maximized at each line portion. i.e. top(5)
and side (6), (6), and side (6), (6
) and yoke (in terms of strength, take the maximum back width dimension respectively. In this example, the top (5) and side (6)
In the middle part, the B line part becomes the maximum back width and is 33v++
It is. Further, in the intermediate portion between the side (6) and the yoke (7), the maximum back width is 35III11 at the D line portion. This frame portion with the maximum back width supports both ends of the vertical gut (8), which is the shortest, and the horizontal gut (9), respectively, in the gut where the ball is actually hit.

The frame is formed by a smooth curved surface in which the back width gradually increases and decreases between the minimum part and the maximum part of the frame back width. The back width of the frame part where these back widths change smoothly is
Precisely, they are determined according to the length of the guts they support.

The above back width dimensions are just one example, and there are infinite combinations considering the material, wall thickness, etc., and the weight of the racket! (peripheral length of the cross section of the frame) and ease of making a mold (mold) are other main factors that are related.

Generally, the material is 100% CFRP or CFRP
Using a material that is a mixture of 80% glass fiber and 20% glass fiber, the wall thickness (1
) is 1 mm and the radius of curvature (a) is constant, then the back sling (
h) The minimum back width is 20-25mm, the maximum back width is 25-3
Take a value in the range of about 51.

Generally, the back width (h) is the top (5) and both sides (6).
, (6), Yoke (assuming each back width of the force is 1, the maximum back width of the portion located in the middle of these is 1.26.

However, this value is just a standard, and there may be problems with appearance,
When the radius of curvature is mainly changed, other adjustments are made as appropriate depending on the wall thickness (1) and the material (Young's modulus E).

In addition, in this example, the top (5) (
The yoke (force (D line part)) had the same minimum back width dimension, but between the maximum part B and the B line part, and the D
The back width dimension of the A line portion and the D line portion may be different as long as it is relatively minimum between the A line portion and the D line portion.

In this example, most of the outer circumferential surface of the frame is made of HP (Hyperbolic P) with a radius of curvature (a) of
a1aboroid, ) formed by a curved surface (hyperbolic paraboloid),
The radius of curvature (a) only near the yoke (7) is λ>0
E P (Elliptic Pa1aboroid
) It is a mixed curved surface composed mainly of HP curved surfaces (elliptic paraboloids), but it may be composed only of HP curved surfaces, or it may be composed of EP convex curved surfaces as shown in Figs. 8 to 14. is also possible.

When this curved surface is considered as the curved surface of the outer peripheral surface of the frame's directly cut section, the HP curved surface has an inverted arch shape (Figs. 15 and 17), and the EP convex curved surface has an arch shape (Figs. 16 and 18). .

The cross section of the shaft part (3) from the yoke part (2) to the end of the grip (4) gradually and smoothly changes in thickness so as to correspond to the thickness of the grip part (4).

In addition, in the embodiments in which the frame outer peripheral surface is an EP convex curved surface shown in FIGS. ■The back width dimension of the ■ line between the 4th line and the J line is maximum.

The back width dimensions of this example drawing are 24 mm each for the smallest F line and J line parts, 251111 mm for the H line part,
It is 26 mm at the G line part, which is the maximum part, and 281 mm at the 1 line part. Moreover, (10) is a concave groove formed with a constant width on the outer peripheral surface side of the EP convex curved surface.

In addition, as in claim 4, the material (Young's modulus E), the wall thickness (
1) may be kept constant and both the back width (h) and the radius of curvature (a) may be varied.

In this case, the top (5) supporting the longest vertical gutt (8)
), each part of the yoke (7), both sides (6) that support the longest horizontal gut (9), and (6), the back width and radius of curvature are formed to the minimum, and each of these parts The maximum part of the back width and the radius of curvature are formed at four locations approximately in the middle of the frame, and the frame is formed by a smooth curve that gradually increases and decreases the back width and the radius of curvature between these parts.

Furthermore, as in the racket frame of the third aspect, the material (Young's modulus E), the wall thickness (1), and the back width (h) may be kept constant and only the radius of curvature (a) may be changed.

In this case, the top (5) supporting the longest vertical gutt (8)
), each part of the yoke (7), and both sides (6), (6) that support the longest horizontal gut (9), the radius of curvature of the cut section of the outer circumferential surface of the frame is minimized to the minimum. However, the maximum radius of curvature of the cut cross section of the outer circumferential surface of the frame is formed at four locations approximately in the middle of each of these portions, and the frame is formed of a smooth curve that gradually increases or decreases the radius of curvature between these portions.

Such a face frame can also be formed by appropriately deforming a pipe-shaped body having an appropriate thickness.

Furthermore, by changing the wall thickness (1) or the material (Young's modulus E), the top (5
), the yoke (7), and the side (6) have the structure that is most difficult to deform, and the shorter support part of the gat can be configured to have a structure that is more easily deformed according to the length of the gat. good.

It is also possible to construct a frame portion having a deformability corresponding to the length of the gutt by a combination of these elements, including the back width (h) and radius of curvature (a).

The operation and theory of the repulsive force of the racket of the racket frame according to the embodiment of this invention is as follows.

Listing the factors that affect the repulsive force of a racket,
As mentioned above, (a) elasticity of the gut, ([+) elasticity around the hole that supports the gut, (c)
There are three possible causes: elasticity of the face frame and shaft. These elasticities (spring forces) are connected in series, so if they do not have equal strength, the weakest spring force will be the main repulsive force, and the repulsive characteristics of the racket will mainly be It is represented by this spring force. Among these, regarding the elasticity around the hole that supports the gutt (b), since the elasticity of the face frame and shaft must be extremely stiff, it will not function as a spring, so in normal cases, the elasticity of the gutt (b) will not function as a spring. Elasticity and ()X)
The elasticity of the face frame and shaft (the elasticity of the part that supports the racket) is considered to influence the elasticity of the racket. And the elasticity (spring force) of Ga Soto
depends on the tension and its length, or is inversely proportional to the length if the tension is constant. However, since the face of a tennis racket is oval, the tension in the gut is the same, but
The lengths are different, and if the length of the central part in the vertical and horizontal directions is 1, the length of the end part of the dowel is 60% (0,6) of that length. Therefore, the strength of the spring force is the reciprocal of 0.6 at the center, that is, about 1.67 times.

In order to equalize the elasticity of the whole strings of these face portions (1), the number of holes supporting the strings may be adjusted depending on the length of the strings.

To do so, the following conditions need to be met.

■ Gatsuto and the supporting part of Gatsuto 7 (structure where the neck is the main body of the racket's repulsive force.

■ In order to satisfy the conditions of ■, the elasticity of the racket's face frame and shaft should be as stiff as possible. For this reason, the circumference of the cross section of the frame is designed to keep the racket weight and swing balance within the target values, and the back sling (
h) is large and the thickness (b) is small to form an oval frame cross section.

■ The supporting force of the gut is determined by the restoring force of the deformation of the outer peripheral curved surface of the face frame.

The strength of this supporting force is determined by the back width (h) of the frame, the radius of curvature (a) of the cut cross section of the outer circumferential surface, and the wall thickness (1), assuming that the material (Young's modulus E) is - constant. be done. If the wall thickness (1) of the frame is constant, it depends on the size of the back rlBh) or the radius of curvature (a).

■ As mentioned above, Gatsuto's spring horn has a spring force approximately 1.67 times stronger at the ends than at the center. Considering the spring force of the support part of the gut, if the support spring force of the end part is about 60% of that of the center part, the spring force of the center part and the end part will be approximately the same strength. However, since the gut and frame are not perpendicular to each other at the end, it is necessary to multiply the cosine of the intersection angle. The angle is between 30 degrees and 60 degrees, and its cosine is 0.87.
Since the spring force is 0.5, the spring force at the ends is about 50% to 30% of that at the center.

■ Assuming that approximately I/2 part of the cross section supports the gutts as an arch whose tension is the back width (h) of the cross section of the frame, the supporting force will be the radius of curvature (a) or the back width (h).
h) is inversely proportional to the cube of the length. If the back width (h) of the center part is set to 1, and the springs at the ends are set to about 50% of the spring force of this part, a cross section with a back width (h) times the cube root of 2 (1,26) is formed. do it. In other words, the top (5) of the face part (1), which is the supporting part of the long gut (HP
Curved surface = A line part, EP curved surface = F line part, same below) Left and right sides (6), (6), (C line part x 2, H line part x
2), yoke (7) (E line part, J line part), assuming that the back width is 1 (minimum part), the four parts (
B line part, D line part) x 2, (G line part, 1 line part) x
The back width (maximum part) of each line part of 2 is the width of each line of 4 above.
The area is approximately 1.26 times larger than the area.

(Effect of the invention) The effects of this invention are as follows.

(1) Because the frame has little bending, vibration is less likely to occur. Even if it occurs, it decays quickly.

(2) The spring that supports the gut is based on the restoring force of the deformation of the outer peripheral curved surface of the frame, so it restores itself with a strong force within a short time and has a momentum that accelerates the return of the deformation of the gut.

Therefore, it has a high coefficient of repulsion and is effective in accelerating the ball at a speed higher than the swing speed of the racket.

(3) Since the support spring of the gut can be coordinated according to the length of the gut, even if the ball is hit off the center of impact, the impact will not be felt much.

The above three points solve all the long-standing problems of conventional racket frames constructed with high rigidity.

Furthermore, as a secondary effect, even when the ball is hit off the sweet spot, there is less impact and vibration than with conventional racket frames, which helps prevent tennis elbow.

[Brief explanation of the drawing]

1 to 19 show embodiments of the invention. Figures 1 to 7 show a tennis racket in which the back width dimension of the face frame is changed and the outer peripheral surface of the frame is mainly an IP curved surface. The figure is a front view of the tennis racket, and FIGS. 3 to 7 are end views (cross-sectional explanatory diagrams) of the face frame section taken along lines A, B, C, D, and E in FIG. 1, respectively. Figure 3 is an end view on line A, Figure 4 is an end view on line B, and Figure 5 is an end view on line B.
The figure is a C-line end view, FIG. 6 is a D-line end view, and FIG. 7 is an E-line end view. FIGS. 8 to 14 show tennis rackets in which the back dimensions are similarly changed and the outer peripheral surface of the frame is composed of 22 curved surfaces.
Figure 8 is a plan view, Figure 9 is a front view, Figures 10 to 14.
The figures are end views (cross-sectional explanatory views) of the face frame portion of each line FlG, H, I, and J in FIG. FIG. 12 is an H-line end view, FIG. 13 is a one-line end view, and FIG. 14 is a J-line end view. Fig. 15 is a cross-sectional explanatory diagram of the HP curved racket frame;
Fig. 16 is a cross-sectional explanatory diagram of a racket frame with 22 curved surfaces;
Figure 17 is a local explanatory diagram of the HP curved surface, and Figure 18 is 22
It is a local explanatory diagram of a curved surface. FIG. 19 is an explanatory diagram showing the deformation of the racket frame when a ball is hit with the racket of the present invention. FIG. 20 and FIG. 21 are conventional examples. FIG. 20 is a cross-sectional explanatory diagram of a conventional racket frame, and FIG. 21 is an explanatory diagram showing deformation of the racket frame when a ball is hit with the conventional racket frame. (1)...Face part 1, (2)...Yoke part, (3)...Shaft part (4)...Grip part 1, ( 5)...Top, (6)...Side, (7)...Yoke (8)...Vertical gut, (9)...・・Horizontal gut, (10) ・・・Groove, ASC, E%PSH, J ・・・・・Minimum frame back width part, B, DSG, 1 ・・・・Maximum frame back width Part, (h)... Back width, (a)... Radius of curvature, (1)... Thickness, (b)... Thickness, ( X)...Face frame outer circumference side, (Y)...
...Inner circumference side of face frame. Patent applicant: Teru Nakamura Patent attorney: Tadashi Yasuhara 2 Masayoshi Yasuhara Brother-in-law 6 Figure Addition Figure 7 Figure 1 Figure 8 Figure 12 Figure 13 Figure 14 Figure 16 Figure 15 Figure 19 Figure 21 Figure 18 Figure 17

Claims (4)

[Claims] (1) Regarding multiple strings stretched in the same direction among the strings stretched on the face part, the frame part that supports the shorter strings is structured to be more easily deformed than the frame part that supports the longer strings. A racket frame that is characterized by: (2) The back width of the frame portions facing each other that support the longest vertical string of the face portion constituting the racket frame and the frame portions facing each other that support the longest horizontal string are configured to be small, and the back width of these frame portions is reduced. It is characterized by comprising a frame part with a large back width in between, and a frame part with a back width that gradually increases or decreases between the frame part with a large back width and the frame part with a small back width. racket frame. (3) In a racket frame in which the back width of the face part constituting the racket frame is constant and the outer peripheral surface is configured as a curved surface, the mutually opposing frame parts that support the longest vertical string of the face part and the longest horizontal string are supported. A frame part with a small radius of curvature of the straight cut cross section curve of the outer peripheral curved surface of the frame parts facing each other, and a frame part with a large curvature radius of the straight cut cross section curve of the frame outer peripheral curved surface between these frame parts. A racket frame characterized in that the outer circumferential curved surface is formed with a frame portion having a radius of curvature that gradually increases or decreases between frame portions with large and small curvature radii of the directly cut section of the outer circumferential curved surface of the frame. (4) The radius of curvature of the straight-cut section of the back width and outer circumferential curved surface of the mutually opposing frame portions that support the longest vertical string of the face portion and the mutually opposing frame portion that supports the longest horizontal string that constitute the racket frame. Between these frame parts, a frame part with a large curvature radius of the cut cross section of the back width and outer peripheral curved surface is constructed, and the back width and the large radius of curvature, and the back width and A racket frame characterized in that it is composed of frame parts formed with a back width and a radius of curvature that gradually increases or decreases between frame parts with a small radius of curvature.