Protective coil and racket

Abstract

It is made possible to improve the rebound performance at the time of hitting a ball with a racket. The wire cover (25-28) is configured with a band portion (31) and a cylinder portion (32) protruding from one side of the band portion. The cylinder portion is provided with a plurality of ribs (36) extending along the extension direction of the center axis (C) of the cylinder main body (35). The plurality of ribs include first ribs (36a) protruding from the outer peripheral surface of the cylinder main body toward both sides in the extension direction of the band portion, and second ribs (36b) protruding from the outer peripheral surface of the cylinder main body toward both sides in a direction orthogonal to the extension direction of the band portion. Two or more first ribs are respectively formed on both sides in the extension direction of the band portion, and one or more second ribs are respectively formed on both sides in the direction orthogonal to the extension direction of the band portion.

Description

TECHNICAL FIELD

[0001] The present application relates to a grommet mounted to a frame of a racket to avoid contact of a string with the frame, and a racket using the grommet. BACKGROUND

[0002] In a racket for tennis or badminton, as disclosed in Patent Literature 1, a frame formed in a ring shape is provided, and a string is stretched on the inner side of the frame to form a face. In addition, a plurality of holes for the string to pass through are formed at regular intervals on the frame. A grommet is mounted in each hole, and a cylindrical portion (hereinafter, referred to as "cylinder portion") of the grommet is interposed between the inner peripheral surface of the hole and the string to avoid contact therebetween.

[0003] With the racket, the string is deformed by flexure at the time of hitting a ball. Due to the deformation by flexure, force is applied to the cylinder portion of the grommet to deform the cylinder portion, and the restoring force due to the deformation of the cylinder portion is applied not only to the string but also to the ball in contact with the string.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2012-517873

[0007] Patent Literature 2: Japanese Patent Application Laid-Open No. Sho 56-4042 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] Each hole of the frame is formed in a circular hole shape, and the cylinder portion of the grommet is formed in a circular cylinder shape. In order to facilitate the work of inserting the cylinder portion into each hole of the frame, the outer diameter of the cylinder portion is formed smaller than the inner diameter of the hole to form a gap between the hole and the cylinder portion. If the gap is formed, when the string is deformed by flexure at the time of hitting a ball with the racket to apply force to the cylinder portion, the cylinder portion is easily deformed by the size of the gap. Due to this deformation of the cylinder portion, there is a problem that the time from the deformation to the recovery of the cylinder portion is lengthened to degrade the rebound performance of the ball hit.

[0010] Here, if the outer diameter size of the cylinder portion is increased to reduce the gap, the cylinder portion is difficult to deform at the time of hitting a ball, but the resistance to insert the cylinder portion into each hole of the frame is increased, and there is a problem that it is difficult to insert the cylinder portion into the hole.

[0011] In Patent Literature 2, a grommet in which ribs are formed in a cylindrical portion is known. The ribs are formed in four at intervals of 90° in the circumferential direction of the cylindrical portion. However, in Patent Literature 2, the position (rotation angle) of the circumferential direction of the cylindrical portion and the ribs in the hole is arbitrary. Although the ribs are pressed against the hole of the frame by the pressing force applied by the tension of the string, in the grommet of Patent Literature 2, the pressing force acts on one rib, and the rib is easily crushed to increase the gap between the hole and the cylindrical portion. Therefore, in the grommet of Patent Literature 2, there is a problem that it is difficult to improve the rebound performance of the ball hit by the racket.

[0012] The present application has been achieved in view of this point, and aims to provide a grommet and a racket capable of improving the rebound performance when a ball is hit with a racket.

[0013] Technical solution for solving the problem

[0014] The grommet according to one aspect of the present application includes a band portion extending in a prescribed direction, and a cylindrical portion protruding from one side of the band portion, and is attached to a frame in the shape of a ring in a racket, characterized in that the cylindrical portion includes a cylindrical main body through which a string passes in a state of penetrating a hole formed in the frame, and a plurality of ribs protruding from an outer peripheral surface of the cylindrical main body and extending in the direction of the central axis in the cylindrical main body, the plurality of ribs including first ribs protruding from the outer peripheral surface of the cylindrical main body toward both sides of the direction of extension of the band portion, and second ribs protruding from the outer peripheral surface of the cylindrical main body toward both sides of a direction orthogonal to the direction of extension of the band portion, two or more of the first ribs being formed on both sides of the direction of extension of the band portion in the cylindrical main body, and one or more of the second ribs being formed on both sides of the direction orthogonal to the direction of extension of the band portion in the cylindrical main body.

[0015] The racket according to one aspect of the present application includes the grommet having a plurality of the cylindrical portions, and a frame in which the string is tensioned in the longitudinal direction and the lateral direction, characterized in that the grommet is attached to the frame with the cylindrical portions penetrating the hole formed in the frame, and the string is tensioned through the plurality of the cylindrical portions.

[0016] Effects of the invention

[0017] According to the present invention, there can be two or more first ribs that are pressed against the holes in the frame by the tension of the strings. This prevents the first ribs from being crushed, making it difficult for gaps to form between the tube and the holes in the frame, thereby suppressing deformation of the tube when the racket is used to hit the ball. Furthermore, second ribs can be formed on both sides in a direction orthogonal to the extension direction of the strip portion, in other words, on both sides in the inward and outward directions of the racket. These second ribs suppress deformation of the tube even when force is applied to it due to string deflection caused by hitting the ball. Thus, with the first and second ribs, the tube is less likely to deform when the racket is used to hit the ball, shortening the time it takes for the tube to return to its original shape after deformation, thereby improving the rebound performance of the shot. Attached Figure Description

[0018] Figure 1 is an external view of the racket involved in the embodiment. Figure 1A This is a front view of the racket. Figure 1B This is a side view of the racket.

[0019] Figure 2 This is a front view illustrating the state of the protective coil after it has been removed from the frame.

[0020] Figure 3 This is a front sectional view of the upper part of the racket, showing the string tension in the embodiment.

[0021] Figure 4 This is a partially enlarged perspective view of the protective coil in the implementation method.

[0022] Figure 5 This is a partial front view of the protective coil in the embodiment.

[0023] Figure 6 yes Figure 3 A sectional view along line AA.

[0024] Figure 7 yes Figure 6 A magnified view of a portion of the image. Detailed Implementation

[0025] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. Furthermore, examples of applying the protective coil according to the present invention to rackets for hard or soft tennis balls will be described below, but the application is not limited thereto and modifications are possible. For example, it can also be applied to rackets for squash, badminton, etc.

[0026] Figure 1 is an external view of the racket according to an embodiment of the present invention. Figure 1A This is a front view of the racket. Figure 1B This is a side view of the racket. Furthermore, for ease of explanation, some components have been omitted from the following figures.

[0027] As shown in Figure 1, the racket 10 includes a head 11 as the hitting part, a handle 12 as the part for the player to hold the racket 10, and a shaft 13 that integrally connects the head 11 and the handle 12. Furthermore, in the following description, as indicated by the arrow in Figure 1, the long side of the racket 10 is defined as the longitudinal direction, the side containing the head 11 along this longitudinal direction is defined as the upper side, and the side containing the handle 12 is defined as the lower side. Additionally, the direction orthogonal to the longitudinal direction on the hitting surface 22 of the racket 10 (i.e., on the plane along the hitting surface 22) is defined as the transverse direction, and the direction orthogonal to the hitting surface 22 of the racket 10 is defined as the inward direction. Figure 1A The front side of the paper ( Figure 1B The left side of the paper is designated as the front side, and its opposite side is designated as the back side.

[0028] Viewed from the inside out, the shaft 13 has a throat 15 that branches into two branches from the handle 12 toward the head 11, on both sides laterally ( Figure 1A A yoke 17 is formed between the throat 15 (left and right sides) of the racket head 11, forming part of the racket head 11. The yoke 17 forms the lower side of the frame 20, which will be described later. In addition, the shaft 13 is not limited to this and may not be branched into two strands.

[0029] The racket head 11 has a ring-shaped frame 20 that is elongated in the longitudinal direction and strings 21 stretched on the inner side of the frame 20 in both the longitudinal and transverse directions. The strings 21 form hitting faces 22 on both the inner and outer surfaces of the inner side of the frame 20. The frame 20 is formed, for example, by molding a hollow cylindrical body made of fiber-reinforced resin into an elliptical shape. Alternatively, the frame 20 may not be hollow and may be filled with foam material, or may be made of wood or metal.

[0030] A groove 20b is provided on the outer peripheral surface 20a of the frame 20, with the central portion being recessed compared to the two side portions in the inward direction. The groove 20b is continuously provided along the circumference of the frame 20. In addition, a through hole 23 is formed in the frame 20, which extends from the bottom side of the groove 20b of the frame 20 to the inner peripheral surface 20c. Multiple through holes 23 are provided along the circumference of the frame 20.

[0031] Figure 2 This is a front view illustrating the state of the protective coil after it has been removed from the frame. Also, as... Figure 2 As shown, four protective coils 25-28 are installed on the outer periphery of the frame 20, and the wire 21 is stretched onto the frame 20 through these protective coils 25-28. In this embodiment, in Figure 2When viewed from the front, the upper guard coil 25 extends from approximately 11 o'clock to approximately 1 o'clock. The guard coils 26 and 27 on the lateral sides extend from near the lateral ends of the upper guard coil 25 to the position of the lowest through-hole 23 formed on the lateral side of the frame 20. Additionally, the lower guard coil 28 is located at the yoke 17. Furthermore, the lengths of each guard coil 25 to 27, except for the lower guard coil 28, along the circumference of the frame 20 can be varied depending on various conditions.

[0032] Each retaining coil 25-28 can be exemplified as a molded body formed by injection molding of thermoplastic resin. Each retaining coil 25-28 has a strip-shaped portion 31 extending in the circumferential direction of the frame 20, and a plurality of cylindrical portions 32 protruding from one side of the strip-shaped portion 31. The front-to-back width of the strip-shaped portion 31 is set to be larger or the same as the front-to-back width of the groove portion 20b, and smaller than the front-to-back width of the frame 20.

[0033] In the cylindrical portion 32, the strip-shaped portion 31 serves as the base, and the top portion, opposite to the base, penetrates through the through hole 23 from the outside of the frame 20. Through this penetration, the protective coils 25-28 are mounted to the frame 20. In this state, the top portion of the cylindrical portion 32 is positioned to protrude inward from the inner circumferential surface 20c of the frame 20. Here, the internal space of each cylindrical portion 32 is formed as an insertion passage 33 through which the wire 21 is inserted (see reference). Figure 3 Furthermore, considering the workability of allowing the wire 21 to pass through, the inner diameter of the insertion passage 33 is larger than the diameter of the wire 21.

[0034] Next, refer to Figure 3 The key points of setting up line 21 in this embodiment will be explained. Figure 3 This is a front sectional view of the upper part of the racket, showing the string tensioning state in the embodiment. Here, the tensioning method of the string 21, which is tensioned longitudinally in the sweet spot of the central region of the frame 20, that is, the warp string 21 that is tensioned in the central region S (see Figure 1), will be explained.

[0035] like Figure 3 As shown, when the frame 20 is stretched with a warp thread 21, for example, when viewed from the position and direction of arrow a1, the thread 21 extends from the top side of the tube 32 towards the base side. Then, the thread 21 folds back at the base (one end side) of the tube 32, becoming the position and direction of arrow a2 along the surface of the strip 31 on the outside of the frame 20. Next, the thread 21 folds back at the base of the adjacent tube 32 in the transverse direction, extending from the base side of the tube 32 towards the top side, becoming the position and direction of arrow a3, and extending longitudinally on the inside of the frame 20.

[0036] This technique is implemented alternately on the lower and upper sides of the frame 20 by a single warp thread 21. Thus, the warp thread 21 is repeatedly inserted and folded back through the insertion passages 33 within the multiple cylindrical sections 32, meandering and extending laterally. At this time, the direction of extension of the thread 21, including the directions of arrows a1 to a3, becomes the direction of tension of the thread 21.

[0037] Next, the specific structure of the tube portion 32 in the upper guard coil 25, that is, the tube portion 32 through which the warp thread 21 in the central region S (see Figure 1) is inserted, will be described. Figure 3 As shown, the cylindrical part 32 has a cylindrical body 35 through which the wire 21 passes when it passes through the through hole 23 of the frame 20.

[0038] Figure 4 This is a partially enlarged perspective view of the protective coil in the implementation method. Figure 5 This is a partial front view of the protective coil in the embodiment. For example... Figure 4 and Figure 5 As shown, in addition to the cylindrical body 35, the cylindrical portion 32 also has multiple ribs 36 protruding from the outer periphery of the cylindrical body 35. The cylindrical body 35 is formed into a shape that gradually tapers from the top end.

[0039] Rib 36 extends along the central axis C of the cylinder body 35, and is formed to the same length as the cylinder body 35 in this direction. Figure 5 As shown, the top end of the cylindrical body 35 protrudes inward from the inner circumferential surface 20c of the frame 20. Consequently, the rib 36, which is the same length as the cylindrical body 35, is formed to extend inward beyond the inner circumferential surface 20c of the frame 20. This allows for an overall increase in rigidity based on the rib 36 along the length of the cylindrical portion 32.

[0040] Figure 6 yes Figure 3 A cross-sectional view along line AA. Besides... Figure 4 In addition, there are also Figure 6 As shown, ribs 36 are formed at equal angles in the circumferential direction of the cylindrical body 35. In this embodiment, six ribs 36 are formed at 60° intervals in the circumferential direction of the cylindrical body 35.

[0041] Figure 7 yes Figure 6 A magnified view of a portion of the image. Also, as... Figure 7 As shown, in the cylindrical section 32, six ribs 36 protrude from the outer peripheral surface of the cylindrical body 35. Here, in the description of the protruding direction of the ribs 36, they will sometimes be referred to as... Figure 6 and Figure 7The extending direction of the left-right strip 31 is simply referred to as the "extending direction". When the retaining coil 25 is mounted on the frame 20, this extending direction is consistent with the extending direction of the ring forming the frame 20. Furthermore, in the description of the protruding direction of the rib 36, the direction orthogonal to the extending direction of the strip 31 is sometimes referred to as... Figure 6 and Figure 7 The vertical direction (in the racket) is referred to as the "orthogonal direction". When the guard coil 25 is installed on the frame 20, this orthogonal direction is consistent with the inside and outside direction of the racket 10.

[0042] In the cylindrical portion 32, six ribs 36 protrude from the outer peripheral surface of the cylindrical body 35 in both the extending direction of the strip portion 31 and in an orthogonal direction relative to the extending direction. More specifically, four of the six ribs 36, two on each side of the extending direction, protrude from the outer peripheral surface of the cylindrical body 35 in both directions of the extending direction; these four ribs 36 are designated as first ribs 36a. Additionally, two of the six ribs 36, one on each side of the orthogonal direction, protrude from the outer peripheral surface of the cylindrical body 35 in both directions of the orthogonal direction; these two ribs 36 are designated as second ribs 36b. In other words, the six ribs 36 in the cylindrical portion 32 include four first ribs 36a and two second ribs 36b.

[0043] The short side of the rib 36 is formed by conical surfaces on both sides, and the width of the short side of the rib 36 increases as it approaches the outer peripheral surface of the cylinder body 35.

[0044] The shape and size of each rib 36 are configured such that, when the cylindrical portion 32 of the above-described shape is inserted into the through hole 23 of the frame 20, the protruding tip side of each rib 36 can contact the inner circumferential surface of the through hole 23. This prevents the cylindrical portion 32 from displacing radially within the through hole 23. Furthermore, when the cylindrical portion 32 is inserted into the through hole 23 to install the coil guard 25 onto the frame 20, it prevents an increase in frictional resistance to the cylindrical portion 32, thus maintaining good workability for installing the coil guard 25.

[0045] In this embodiment, the racket 10 is configured to have multiple tube portions 32 in each of the guard coils 25 to 28, but the tube portion 32 having the multiple ribs 36 described above may also be a part of it.

[0046] To illustrate specifically, the cylindrical portion 32 with multiple ribs 36 is configured to allow the warp threads 21 to pass through. Alternatively, the cylindrical portion 32 through which the warp threads 21 pass through the central region S can also have multiple ribs 36. Specifically, when there are 16 warp threads 21, multiple ribs 36 are formed in the cylindrical portions 32 (in other words, 10 cylindrical portions 32) that allow 10 warp threads (threads 21) to pass through in the upper center of the left-right direction, and multiple ribs 36 are formed in the cylindrical portions 32 (in other words, 6 cylindrical portions 32) that allow 6 warp threads to be inserted in the lower center of the left-right direction (yoke 17). This is because players mostly use the upper part of the frame 20 to hit the ball, and the force is easily applied to the upper part of the racket 10, making the upper cylindrical portion 32 of the frame 20 easy to move, but it is necessary to restrict the movement of this upper cylindrical portion 32. In addition, when a portion of the multiple cylindrical portions 32 is provided with multiple ribs 36, the outer peripheral surface of the other cylindrical portions 32 is formed by the outer peripheral surface of the cylinder through the cylinder body 35.

[0047] When the wire 21 is stretched as described above, the stretching direction of the wire 21 is meandering, so that the cylindrical portion 32 is pressed against the through hole 23 in the extending direction of the strip portion 31. In this state, for example in Figure 7 In the cylindrical section 32 shown, the line 21, which passes through the insertion passage 33 and then folds back, is pressed to the right side of the figure. Figure 7 The cylindrical portion 32 protrudes from the right side of the cylindrical body 35 in this figure, forming two first ribs 36a, thus suppressing the crushing deformation of the first ribs 36a themselves. As a result, it is difficult for gaps to form between all the ribs 36 and the through holes 23.

[0048] Furthermore, for the cylindrical portion 32, there exists a line 21 that folds back after passing through the insertion passage 33 and... Figure 3 Conversely, pressing to the left (see reference) Figure 6 and ​ Even in this case, since two first ribs 36a protrude from the main body 35 on both sides of the extension direction of the strip portion 31, the crushing deformation of the first ribs 36a themselves can be suppressed.

[0049] When the ball is hit using the racket 10 in this embodiment, the string 21 stretched in the longitudinal direction is subjected to forces in the inward and outward directions and in the lateral direction, causing it to bend. Due to the bending of the string 21, the upper and lower guard loops 25, 28 are subjected to a force and deformed in their cylindrical portions 32, and the restoring force resulting from this deformation acts on the string 21. Thus, in addition to the restoring force of the bent string 21, the restoring force of the cylindrical portions 32 also acts on the ball, and through these forces, the ball is bounced away.

[0050] Here, four first ribs 36a are formed in the barrel portion 32, thereby making it difficult for gaps to form between the barrel portion 32 and the through hole 23 of the frame 20 due to the tension of the string 21. As a result, deformation of the barrel portion 32 when hitting the ball with the racket 10 can be suppressed. Moreover, second ribs 36b are formed protruding from the barrel body 35 in the directions corresponding to the inside and outside directions of the racket 10, so even if the string 21 bends significantly in the inside and outside directions due to hitting the ball, the force generated by this bend can be used to suppress deformation of the barrel portion 32.

[0051] In this embodiment, because the barrel 32 has a first rib 36a and a second rib 36b, it is difficult for the barrel 32 to deform when the racket 10 is used to hit the ball. As a result, the time from deformation of the barrel 32 to returning to its original shape can be shortened, thereby improving the rebound performance of the hit and enabling faster ball speed.

[0052] Furthermore, since the position of the cylindrical portion 32 around the central axis C can be fixed by the strip portion 31, the rotation of the cylindrical portion 32 around the central axis C within the through hole 23 can be restricted. This prevents the number of first ribs 36a from decreasing to less than one on each side of the extension direction of the strip portion 31, maintaining a total of two ribs. Therefore, in the cylindrical portion 32 having the first rib 36a and the second rib 36b, the aforementioned rebound performance of the ball can be stably achieved.

[0053] Furthermore, during continuous use of the racket 10, the shaft 32 is subjected to load through repeated pulling and switching of the strings 21, but this load also suppresses the crushing deformation of the first rib 36a itself. As a result, the aforementioned rebound performance effect can be obtained over a long period of time.

[0054] Furthermore, the tube portion 32 has multiple ribs 36, which are formed to the same length as the tube body 35 and extend inward beyond the inner circumferential surface 20c of the frame 20. Therefore, the rigidity of the tube portion 32 can be increased by the ribs 36. With the increased rigidity of the tube portion 32, the tube portion 32 becomes less prone to deformation when hitting the ball with the racket 10, and the aforementioned rebound performance effect can be obtained.

[0055] Furthermore, the warp line 21 has a significant impact on hitting performance, including rebound performance. Therefore, by forming a first rib 36a and a second rib 36b in the cylindrical portion 32 through which the warp line 21 is inserted, the aforementioned effect can be achieved efficiently. Moreover, by forming the first rib 36a and the second rib 36b in the cylindrical portion 32 through which the warp line 21 is inserted, the aforementioned effect can be achieved even more efficiently.

[0056] Here, since the tube portion 32, which is configured such that the weft threads 21 are inserted on both sides of the frame 20, does not have ribs 36, the rebound performance may be suppressed. However, compared to the rebound performance, the weft threads 21 are more helpful for the feel of hitting the ball, and can be designed to complement the rebound performance of the warp threads 21 and the tube portion 32 with ribs 36, so that the racket 10 as a whole can achieve good balance.

[0057] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be made to implement it. In the above embodiments, the size, shape, orientation, etc., of the figures shown are not limited thereto, and appropriate modifications can be made within the scope of achieving the effects of the present invention. In addition, appropriate modifications can be made to implement the invention without departing from the scope of its objectives.

[0058] For example, ribs 36 may be provided for the cylindrical portion 32 through which the latitude line 21 is inserted. In this case, the orientation of the cylindrical portion 32 through which the longitude line 21 is inserted is changed by 90° from the longitudinal direction to the transverse direction.

[0059] Furthermore, in the cylindrical portion 32, for a single cylindrical body 35, it is sufficient that two or more first ribs 36a are formed on each side of the extending direction of the strip portion 31, such as three or four. Similarly, for a single cylindrical body 35, it is sufficient that one or more second ribs 36b are formed on each side of the direction orthogonal to the extending direction of the strip portion 31, such as two or three. Therefore, an example can be provided where eight ribs 36 are formed at 45° intervals along the circumference of the cylindrical body 35.

[0060] Industrial availability

[0061] This invention relates to a retainer coil that can improve the rebound performance when hitting a ball with a racket, and a racket using the retainer coil.

[0062] This application is based on Japanese Special Application 2021-012755, filed on January 29, 2021. Its entire contents are contained herein.

Claims

1. A racket that has: A protective coil, comprising a strip-shaped portion extending in a predetermined direction and a plurality of cylindrical portions protruding from one side of the strip-shaped portion; and The frame has lines stretched along its longitudinal and transverse directions in a ring shape. Its features are, The plurality of cylindrical sections are each passed through a hole formed in the frame to mount the protective coil onto the frame, and the wire passes through the plurality of cylindrical sections and is stretched. One of the plurality of cylindrical portions includes: A cylindrical body, through which the wire passes in a state that extends through the hole formed in the frame; and Multiple ribs are formed on the outer peripheral surface of the cylinder body to project from the outer peripheral surface and extend along the direction of extension of the central axis in the cylinder body. The plurality of ribs includes a first rib protruding from both sides of the outer peripheral surface of the cylindrical body toward the extending direction of the strip portion, and a second rib protruding from both sides of the outer peripheral surface of the cylindrical body toward a direction orthogonal to the extending direction of the strip portion. The first rib has two or more branches on each side of the extending direction of the strip-shaped portion in the main body of the cylinder. The second rib is formed in two or more directions on both sides of the cylindrical body, which are orthogonal to the extending direction of the strip-shaped portion. The plurality of ribs are formed to extend inward beyond the inner circumferential surface of the frame. Each of the plurality of ribs has such a shape and size that, when the plurality of cylindrical parts are respectively inserted into the holes formed on the frame, the top end of each of the plurality of ribs protruding from the outer peripheral surface of the cylindrical body can contact the inner peripheral surface of the holes formed on the frame.

2. The racket according to claim 1, characterized in that, Two first ribs are formed on each side of the extending direction of the strip portion in the cylindrical body, and one second rib is formed on each side of the direction orthogonal to the extending direction of the strip portion in the cylindrical body.

3. The racket according to claim 1, characterized in that, One of the plurality of cylindrical sections is provided for the wire insertion, which is stretched longitudinally and passes through the central region of the frame.

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