racket

Abstract

The present invention provides a racket that can achieve excellent rebound performance without relying on the specifications of a wire guard tube (10). The tennis racket has a racket frame (4) and a wire guard tube (10). The racket frame (4) has a wire guard tube groove (22), a small groove (38) and a hole (24). The small groove (38) is recessed from the wire guard tube groove (22). The wire guard tube (10) has a base (26) and a tube (28). When the wire guard tube (10) is installed on the racket frame (4), the base (26) is accommodated in the wire guard tube groove (22), and the tube (28) passes through the hole (24). The base 26 does not enter the small groove (38). Therefore, there is a space provided by the small groove (38) on the further back side of the back side surface (32) of the base (26).

Description

Technical Field

[0001] The present invention relates to a racket for tennis or the like. Background Art

[0002] A tennis racket has a racket frame and strings. A tennis player hits a ball with the racket. The hit ball flies toward the opponent's court. A faster flying ball can help the tennis player win.

[0003] Japanese Patent Publication No. 2019-107057 discloses a tennis racket having a groove in the racket frame. The racket having the groove has a large deformation amount when hitting a ball. Therefore, the racket has excellent rebound performance.

[0004] In the past, the strings were directly passed through the hole formed in the frame. In recent years, the strings are passed through the hole via the wire guard tube in the tennis racket.

[0005] Japanese Patent Publication No. 2002-537004 discloses a tennis racket having a wire guard tube including a shank. The racket has a space between the racket frame and the wire guard tube. Therefore, the wire guard tube can be bent toward the racket frame. The bending of the wire guard tube contributes to the rebound performance of the racket.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2019-107057

[0009] Patent Document 2: Japanese Patent Application No. 2002-537004 Summary of the invention

[0010] Problems to be solved by the invention

[0011] In the racket disclosed in Japanese Patent Application Publication No. 2019-107057, the groove is exposed to the outer peripheral surface of the racket head. Therefore, the depth of the groove is uneven due to the grinding performed when the racket frame is manufactured. The uneven depth will impair the rebound performance and appearance.

[0012] In order to achieve sufficient flexure, the wire guard disclosed in Japanese Patent Publication No. 2002-537004 requires a sufficient thickness. However, a racket having a wire guard that is too thick has a large mass. Since a thick wire guard protrudes greatly from the wire guard groove, air resistance during a swing is increased. The protruding wire guard easily rubs against the ground during a swing. A deeper wire guard groove suppresses the protrusion of the wire guard. However, a deeper wire guard groove impairs the strength of the racket frame. The improvement in rebound performance brought about by the handle is limited.

[0013] An object of the present invention is to provide a racket that can achieve excellent rebound performance without depending on the specifications of a cord guard.

[0014] Means to solve problems

[0015] The racket of the present invention comprises a wire guard tube, a racket frame and a racket string. The wire guard tube comprises a base and a tube, the tube standing upright from the base and allowing the racket string to pass through. The racket frame comprises a wire guard tube groove accommodating the base and a small groove recessed from the wire guard tube groove.

[0016] Preferably, the width of the small groove is greater than or equal to 0.5 mm and less than or equal to 1.5 mm. Preferably, the depth of the small groove is greater than or equal to 0.1 mm and less than or equal to 1.0 mm.

[0017] Preferably, the ratio of the width of the small groove to the diameter of the string is 50% or more and 100% or less.

[0018] In the racket frame for a racket involved in the present invention, a wire guard tube and strings can be installed. The wire guard tube has a base and a tube standing upright from the base. The racket frame has: a wire guard tube groove accommodating the base; and a small groove recessed from the wire guard tube groove.

[0019] Effects of the Invention

[0020] In the racket involved in the present invention, when colliding with a ball, the base bends toward the center of the surface. This bending is a slight deformation. The deformed base will then recover. Through this deformation and recovery, a large amount of kinetic energy is transmitted to the ball, etc. The racket has excellent rebound performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a front view showing a racket according to an embodiment of the present invention.

[0022] Figure 2 Yes Display Figure 1 An enlarged exploded view of a portion of a racket.

[0023] Figure 3 Yes Display Figure 1 An enlarged right side view of a portion of the racket head of a racquet.

[0024] Figure 4 is along Figure 3 Cross-sectional view along line IV-IV.

[0025] Figure 5 is along Figure 4 An enlarged cross-sectional view taken along line VV.

[0026] Figure 6 Yes Figure 4 An enlarged view of a portion of the racquet head shown with the guard tube and strings.

[0027] Figure 7 It is along Figure 6 Cross-sectional view along line VII-VII.

[0028] Figure 8 is along Figure 6 Cross-sectional view along line VIII-VIII.

[0029] Fig. 9 It is a perspective view showing a wire guard tube of a racket according to another embodiment of the present invention.

[0030] Fig.10 This is a graph showing the evaluation results of the racket according to Example 1 of the present invention together with the evaluation results of the racket according to Comparative Example 1.

[0031] Fig.11 This is a graph showing the evaluation results of the racket according to Example 1 of the present invention and the evaluation results of the racket according to Comparative Example 1 together.

[0032] [Explanation of symbols]

[0033] 2. Tennis racket

[0034] 4. Shooting frame

[0035] 10, 40···Grommet

[0036] 12···beat the string

[0037] 14. Head shot

[0038] 22···Wire protection groove

[0039] 24···Kong

[0040] 26, 42···Base

[0041] 28, 44···Tube

[0042] 30, 46···Table side

[0043] 32, 48···dorsal side

[0044] 34···Line

[0045] 36···Surface

[0046] 38···Small slot DETAILED DESCRIPTION

[0047] Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

[0048] Figure 1 and Figure 2 A tennis racket 2 is shown. The tennis racket 2 has a racket frame 4, a grip 6, an end cap 8, a grommet 10, and strings 12. The tennis racket 2 can be used for hard tennis. Figure 1 In FIG. 1 , arrow X indicates the width direction of the tennis racket 2 , and arrow Y indicates the axial direction of the tennis racket 2 .

[0049] The racket frame 4 has a racket head 14, two throats 16 and a handle 18. The racket head 14 forms an outline of a surface (described in detail later). The front shape of the racket head 14 is roughly elliptical. The major diameter direction of the ellipse coincides with the axial direction Y of the tennis racket 2. The minor diameter direction of the ellipse coincides with the width direction X of the tennis racket 2. One end of each throat 16 is continuous with the racket head 14. The throat 16 merges with another throat 16 near the other end. The throat 16 extends from the racket head 14 to the handle 18. The handle 18 extends from the portion where the two throats 16 merge. The handle 18 is formed continuously and integrally with the throat 16. The portion sandwiched by the two throats 16 in the racket head 14 is the yoke 20. At Figure 1 In FIG. 1 , symbol Tp represents the top of the racket head 14 .

[0050] The frame 4 is hollow. The material of the frame 4 is fiber-reinforced resin. In this embodiment, the matrix resin of the fiber-reinforced resin is a thermosetting resin. A typical thermosetting resin is an epoxy resin. A typical fiber of the fiber-reinforced resin is a carbon fiber. The fiber is a long fiber.

[0051] like Figure 2 As shown, the racket head 14 has a wire protection tube groove 22. The wire protection tube groove 22 is recessed from the outer peripheral surface of the racket head 14. Figure 1 As shown, the grommet groove 22 is formed on substantially the entire circumference of the head 14 excluding the shoulder 20 .

[0052] The head 14 further has a plurality of holes 24. Each hole 24 penetrates the head 14. The plurality of holes 24 are arranged on substantially the entire circumference of the head 14.

[0053] The grip 6 is formed of a tape wound around a handle 18. The grip 6 suppresses slippage between the hand of a player and the tennis racket 2 when the player swings the tennis racket 2. An end cap 8 is attached to the end of the grip 6.

[0054] like Figure 2 As shown, the cable protection tube 10 has a base 26 and a plurality of tubes 28. The base 26 has a belt shape. The base 26 has a front side 30 and a back side 32. The shape of the front side 30 is generally flat. The shape of the back side 32 is generally flat. Each tube 28 is formed integrally with the base 26. The tube 28 stands upright from the base 26.

[0055] exist Figure 2 In FIG. 1 , arrow Tc indicates the thickness of the base 26. From the viewpoint of the strength of the base 26, the thickness Tc is preferably 0.5 mm or more, more preferably 0.7 mm or more, and particularly preferably 0.8 mm or more. From the viewpoint of lightness, the thickness Tc is preferably 1.5 mm or less, more preferably 1.3 mm or less, and particularly preferably 1.2 mm or less.

[0056] The wire tube 10 is typically made of a synthetic resin that is softer than the frame 4. The racket 2 may have a plurality of wire tubes 10. A wire tube 10 may be spaced apart from adjacent wire tubes 10. The number of tubes 28 in each wire tube 10 may be one.

[0057] The cable conduit 10 is mounted on the racket head 14. When the cable conduit 10 is mounted on the racket head 14, the base 26 is accommodated in the cable conduit groove 22. A portion of the base 26 may protrude from the cable conduit groove 22. Further, when the cable conduit 10 is mounted on the racket head 14, the tube 28 penetrates the hole 24.

[0058] like Figure 1 As shown, the string 12 is hung on the racket head 14. The string 12 is hung along the width direction X and the axial direction Y. A plurality of threads 34 are formed by the string 12. The portion of the string 12 extending along the width direction X is called a horizontal thread 34a. The portion of the string 12 extending along the axial direction Y is called a vertical thread 34b. A surface 36 is formed by a plurality of horizontal threads 34a and a plurality of vertical threads 34b. The surface 36 is generally along the XY plane. The surface 36 may be formed by two or more strings 12.

[0059] Figure 3 Yes Display Figure 1 An enlarged right side view of a portion of the racket head 14 is shown. Figure 4 is along Figure 3 Cross-sectional view along line IV-IV. Figure 5 is along Figure 4 The enlarged cross-sectional view of the VV line. Figure 3-5 The wire guard tube 10 and the string 12 are not shown. Figure 3 , arrow Z indicates the thickness direction.

[0060] like Figure 3-5 As shown, the frame 4 has a plurality of small grooves 38. Figure 4 and Figure 5 As shown, each small groove 38 is recessed from the wire protection tube groove 22. Figure 3 and Figure 4As shown, the small groove 38 is sandwiched between the two holes 24. The small groove 38 extends from the hole 24 to another hole 24 adjacent to the hole 24. The small groove 38 is formed on the substantially entirety of the racket head 14 except the racket shoulder 20. Figure 5 As shown, in this embodiment, the cross-sectional shape of the small groove 38 is substantially semicircular. The small groove 38 may have other cross-sectional shapes.

[0061] Figure 6 Yes Figure 4 A portion of the racket head 14 is shown in an enlarged view together with the wire guard tube 10 and the racket string 12, Figure 7 It is along Figure 6 The cross-sectional view of line VII-VII, Figure 8 is along Figure 6 Cross-sectional view along line VIII-VIII.

[0062] exist Figure 6-8 In the racket, the cable guard 10 is mounted on the racket head 14. The base 26 is accommodated in the cable guard groove 22, and the back side surface 32 of the base 26 contacts the bottom surface of the cable guard groove 22. Each tube 28 passes through the hole 24. The axial direction of the tube 28 is substantially consistent with the axial direction of the hole 24.

[0063] exist Figure 6-8 In the racket, the strings 12 are hung on the racket head 14. Figure 6 As shown, a portion of the string 12 is in contact with the base 26. The string 12 is bent near the boundary between the base 26 and the tube 28. A portion of the string 12 passes through the tube 28.

[0064] from Figure 6 and Figure 8 It is clear that the base 26 hardly enters the small groove 38. The base 26 is separated from the bottom of the small groove 38. Therefore, there is a space brought by the small groove 38 on the further back side of the back side surface 32 of the base 26.

[0065] When a tennis ball is hit with the tennis racket 2, the surface 36 receives an impact from the tennis ball when the ball is hit. Due to the impact, the surface 36 is deformed. Specifically, the surface 36 is bent in the direction opposite to the swing direction. This bending is accompanied by the extension of the string 12.

[0066] Due to the stretching of the string 12, in the string 12, Figure 7 The tension is generated in the direction indicated by the arrow A1. Due to this tension, the portion of the string 12 that contacts the base 26 moves Figure 8 The base 26 is pressed in the direction indicated by the middle arrow A2.

[0067] The base 26 is bent by being pressed by the string 12. The direction of the bending is Figure 8The base 26 is bent in the direction indicated by the arrow A2. As described above, there is space on the back side of the base 26 due to the small groove 38. Therefore, the base 26 can be bent without being hindered by the frame 4. In other words, the base 26 can be bent in a relatively free state. The deformation amount of the base 26 is large.

[0068] The deflected surface 36 recovers after the ball is hit. The stretched string 12 recovers after the ball is hit. Therefore, the deflected base 26 recovers after the ball is hit.

[0069] A general tennis racket transmits energy to a tennis ball by stretching and restoring the strings 12. The tennis racket 2 according to the present invention transmits energy to a tennis ball by bending and restoring the base 26 in addition to stretching and restoring the strings 12. When the tennis ball is hit with the tennis racket 2, the tennis ball flies at high speed. The tennis racket 2 has excellent rebound performance.

[0070] When a tennis ball is hit at a position far from the center of the surface 36, the string 12 is not stretched sufficiently. However, the deflection of the base 26 makes up for the lack of stretching. Therefore, even when a tennis ball is hit at a position far from the center of the surface 36, the tennis ball flies at a relatively high speed.

[0071] The flexure of the base 26 can also help absorb the shock. Even when a tennis ball is hit at a position far from the center of the surface 36, an excellent hitting feel can be obtained through the tennis racket 2.

[0072] In the tennis racket 2, the small groove 38 is covered by the base 26. Therefore, the small groove 38 does not spoil the appearance of the tennis racket 2. In addition, since the vicinity of the small groove 38 does not directly collide with the bottom surface, the tennis racket 2 is difficult to be damaged.

[0073] The tennis racket 2 does not need a thick base 26. Therefore, the tennis racket 2 can be lightweight. In the tennis racket 2, the base 26 protrudes from the grommet groove 22 by a small amount. Therefore, the air resistance during the swing of the tennis racket 2 is small. In the tennis racket 2, the friction between the grommet 10 and the ground is suppressed. The tennis racket 2 may also have the small groove 38 and the grommet with a handle disclosed in the Japanese Patent Publication No. 2002-537004.

[0074] exist Figure 3, arrow Wd indicates the width of the small groove 38. The width Wd is measured along the thickness direction. The width Wd is preferably not less than 0.5 mm and not more than 1.5 mm. In the tennis racket 2 having a width Wd of not less than 0.5 mm, the base 26 is sufficiently bent. From this viewpoint, the width Wd is more preferably not less than 0.7 mm, and particularly preferably not less than 0.8 mm. In the tennis racket 2 having a width Wd of not more than 1.5 mm, the base 26 that has entered the small groove 38 is prevented from escaping from the small groove 38. From this viewpoint, the width Wd is more preferably not more than 1.3 mm, and particularly preferably not more than 1.2 mm.

[0075] exist Figure 7 , arrow Dm indicates the diameter of the string 12. The ratio of the width Wd of the small groove 38 to the diameter Dm of the string 12 is preferably 50% or more and 100% or less. In the tennis racket 2 in which the ratio is 50% or more, the base 26 is sufficiently bent. From this viewpoint, the ratio is more preferably 60% or more, and particularly preferably 65% ​​or more. In the tennis racket 2 in which the ratio is less than 100%, the base 26 that has entered the small groove 38 is prevented from escaping from the small groove 38. From this viewpoint, the ratio is more preferably 90% or less, and particularly preferably 85% or less. In the case where the cross-sectional shape of the string 12 is non-circular, the diameter of the circle circumscribed with the shape is the diameter Dm.

[0076] exist Figure 5 In FIG. 1 , arrow Dp indicates the depth of the small groove 38. The depth Dp is preferably 0.1 mm or more and 1.0 mm or less. In the tennis racket 2 having a depth Dp of 0.1 mm or more, the base 26 is sufficiently bent. From this viewpoint, the depth Dp is more preferably 0.2 mm or more, and particularly preferably 0.3 mm or more. The strength of the tennis racket 2 having a depth Dp of 1.0 mm or less is excellent. From this viewpoint, the depth Dp is more preferably 0.8 mm or less, and particularly preferably 0.7 mm or less.

[0077] In the present embodiment, as described above, a plurality of small grooves 38 are formed on substantially the entirety of the racket head 14. The small grooves 38 may be formed only on a portion of the racket head 14. In the present embodiment, the horizontal wire 34a is shorter than the vertical wire 34b. Therefore, the stretching amount of the horizontal wire 34a tends to be smaller than the stretching amount of the vertical wire 34b. By forming the small grooves 38 in the region of the racket head 14 sandwiched between the two horizontal wires 34a, the small grooves 38 compensate for the insufficient stretching of the horizontal wire 34a.

[0078] An example of a method for manufacturing a tennis racket 2 of the present invention is described below. In this manufacturing method, a mandrel, a pipe, and a plurality of prepregs are prepared. Each prepreg is composed of a plurality of reinforcing fibers and a matrix resin arranged in parallel. In this manufacturing method, first, a mandrel is inserted into the pipe. The prepregs are wound around the pipe in sequence. The prepregs are wound into a cylindrical shape.

[0079] After the mandrel is extracted from the pipe, the pipe and the prepreg are placed in a mold. The mold has a small ridge (a small protrusion (Japanese: sujiyama)) on the surface of the cavity. In the mold, the pipe is filled with gas, so that the pipe expands. By this expansion, the prepreg is pressed to the surface of the cavity of the mold. The prepreg is heated, so that the matrix resin is cured. A molded body is obtained by curing. The molded body has a shape that is the inversion of the shape of the cavity surface. The molded body has a small groove 38. The small groove 38 has a shape that is the inversion of the shape of the ridge.

[0080] The molded body has a hole 24 passing through it. Further, the molded body is subjected to surface grinding, painting, and the like to obtain a frame 4. The frame 4 is provided with a grip 6, a wire guard 10, and the like. Further, the strings 12 are hung on the frame 4 to complete the tennis racket 2.

[0081] Fig. 9 4 is a perspective view showing a wire guard tube 40 of a racket according to another embodiment of the present invention. Figure 1-8 The racket 2 shown also has a grommet groove and small grooves.

[0082] The wire protection tube 40 has a base 42 and a tube 44. The base 42 has a disc shape. The base 42 has a front side 46 and a back side 48. The front side 46 is generally flat in shape. The back side 48 is generally flat in shape. The tube 44 is formed integrally with the base 42. The tube 44 stands upright from the base 42.

[0083] exist Fig. 9 In FIG. 4 , arrow Tc indicates the thickness of base 42. Thickness Tc is Figure 2 The thickness Tc shown is the same.

[0084] As mentioned above, the frame of the racket has a wire guard tube groove. When the wire guard tube 40 is installed on the frame, the back side surface 48 abuts against the bottom of the wire guard tube groove.

[0085] As mentioned above, the racket frame of the racket has a small groove. Therefore, in the racket, there is a space further back than the back side surface 48. In the racket, the base 42 can be easily deformed by the stretching of the strings. In addition to the stretching and recovery of the strings, the racket also transmits energy to the ball (or badminton) by the bending and recovery of the base 42. When the racket is hit, the ball flies at high speed. The racket has excellent rebound performance.

[0086] Example

[0087] Hereinafter, the effects of the present invention will be explained by way of examples, but the present invention should not be interpreted in a limited manner based on the description of the examples.

[0088] [Experiment 1]

[0089] [Example 1]

[0090] The racket frame is made by curing the matrix resin of the prepreg in a mold having ridges. Figure 1-8 The tennis racket shown. The racket has many small grooves. The width Wd of the small grooves is 1.0 mm. The depth Dp of the small grooves is 0.5 mm.

[0091] [Comparative Example 1]

[0092] A tennis racket of Comparative Example 1 was obtained in the same manner as in Example 1 except that a different mold was used. The mold did not have ridges. Therefore, the tennis racket did not have small grooves.

[0093] [Rebound coefficient]

[0094] A tennis ball is made to fly at a speed of 30 m / s and collide with the surface of a tennis racket. After the collision, the tennis ball rebounds. The speed of the tennis ball before the collision and the speed of the tennis ball after the collision are measured, and the rebound coefficient is calculated. The rebound coefficient is measured at the five measurement points shown in the following Table 1. In Table 1, x is the distance from the origin in the X direction, and y is the distance from the origin in the Y direction. The origin is the center of the surface.

[0095] Table 1 Measurement points of rebound coefficient

[0096]

[0097] The results of this measurement are shown in Fig.10 In the coordinate diagram of Fig.10 In the figure, the horizontal axis is the distance from the center to the measuring point, and the vertical axis is the rebound coefficient. Fig.10 It can be clearly seen that the tennis racket of Example 1 has excellent rebound performance in the entire width direction.

[0098] [Experiment 2]

[0099] The coefficient of repulsion was measured at five of the eight measurement points shown in Table 2 below using the tennis rackets of Example 1 and Comparative Example 1 used in Experiment 1. In Table 2, x is the distance from the origin in the X direction, and y is the distance from the origin in the Y direction. The origin is the top.

[0100] Table 2 Measurement points of rebound coefficient

[0101]

[0102] The results of this measurement are shown in Fig.11 In the coordinate diagram of Fig.11 In the figure, the horizontal axis is the distance from the top to the measuring point, and the vertical axis is the rebound coefficient. Fig.11 It is clear that the tennis racket of Example 1 has excellent rebound performance in the entire axial direction.

[0103] [Experiment 3]

[0104] [Examples 2-4]

[0105] Except for using different molds, tennis rackets of Examples 2 to 4 were obtained in the same manner as in Example 1. The dimensions of the grooves of these tennis rackets are shown in Table 3 below.

[0106] [Rebound coefficient]

[0107] The coefficient of restitution at the center of the surface of each tennis racket was measured in the same manner as in Experiment 1. The results are shown in Table 3 below.

[0108] Table 3 Measurement results

[0109]

[0110] As is clear from Table 3, the tennis rackets of the respective examples have excellent rebound performance.

[0111] [Summarize]

[0112] According to the results of Experiments 1-3, the advantages of the present invention are obvious.

[0113] Industrial Applicability

[0114] The racket involved in the present invention can be used in various games such as soft tennis, squash, badminton, etc.

Claims

1. A racket, wherein: The racket comprises a wire guard tube, a racket frame and a racket string. The wire guard tube has a base and a tube, the tube is erected from the base and is for the strings to pass through, The racket frame has: a wire protection tube groove accommodating the base; and a small groove recessed from the wire protection tube groove. The base is separated from the bottom of the small groove, and there is a space on the back side of the base caused by the small groove. The small groove extends from a hole that passes through the racket frame and the racket head to another hole adjacent to the hole. The width of the small groove is not less than 0.5 mm and not more than 1.5 mm, The depth of the small groove is greater than or equal to 0.1 mm and less than or equal to 1.0 mm. A ratio of the width of the small groove to the diameter of the string is greater than or equal to 50% and less than or equal to 100%.

2. The racket according to claim 1, wherein: The width of the small groove is greater than or equal to 0.7 mm and less than or equal to 1.3 mm.

3. The racket according to claim 1, wherein: The width of the small groove is greater than or equal to 0.8 mm and less than or equal to 1.0 mm.

4. The racket according to claim 1, wherein: The depth of the small groove is greater than or equal to 0.2 mm and less than or equal to 0.7 mm.

5. The racket according to claim 1, wherein: The depth of the small groove is greater than or equal to 0.3 mm and less than or equal to 0.5 mm.

6. The racket according to any one of claims 1 to 5, wherein: A ratio of the width of the small groove to the diameter of the string is greater than or equal to 65% and less than or equal to 85%.

7. A racket frame for a tennis racket, capable of being equipped with a wire guard tube and strings, wherein the wire guard tube has a base and a tube erected from the base, wherein: The racket frame has: a wire protection tube groove accommodating the base; and a small groove recessed from the wire protection tube groove. When the base is accommodated in the wire protection tube groove, the base is separated from the bottom of the small groove, and there is a space on the back side of the base caused by the small groove. The small groove extends from a hole that passes through the racket frame and the racket head to another hole adjacent to the hole. The width of the small groove is not less than 0.5 mm and not more than 1.5 mm, The depth of the small groove is greater than or equal to 0.1 mm and less than or equal to 1.0 mm. A ratio of the width of the small groove to the diameter of the string is greater than or equal to 50% and less than or equal to 100%.

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