JP2014171524A - Racket and grommet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge a sweet spot of a racket without changing the shape of a frame.SOLUTION: A racket comprises: a grip; an annular frame having a plurality of through-holes penetrating from an inner circumference to an outer circumference; a shaft for connecting the grip and the frame to each other; and a grommet which is attached to the outer circumference of the frame, includes a plurality of cylinder parts inserted into the plurality of through-holes formed in the frame, respectively, and a base part having a plurality of communication holes connecting the cylinder parts to one another and having communication holes communicating with the insides of the respective cylinder parts, and enables strings to be inserted into the cylinder parts and the communication holes. In the racket, when either the longitudinal direction of a racket or a direction orthogonal to the longitudinal direction on the hitting face of the racket is made a first direction, the portion of a base part to be attached to a second position on the outer side in the first direction than the first position has thickness from the inner circumference to the outer circumference larger than the portion of the base part to be attached to the first position in the first direction in the outer circumference of the frame.

Description

  The present invention relates to a racket used for tennis or the like, and a grommet attached to the racket.

  2. Description of the Related Art A racket used for tennis or the like is known that has a grip held by a player, a frame on which a string is stretched, and a shaft that connects the grip and the frame. The frame is provided with a plurality of string holes for inserting the strings along the circumferential direction of the frame. In general, a string is stretched on a frame via a grommet including a plurality of cylindrical portions and a base portion connecting them. Specifically, in a state in which the cylinder part of the grommet is passed through the string hole of the frame, the string that protrudes from the inside of the frame to the outside of the frame through the inside of the grommet part is folded back along the base part of the grommet and the next cylinder The operation of passing through the part is repeated. As a result, string portions (longitudinal strings) along the longitudinal direction of the racket are stretched in the frame at intervals in the width direction intersecting the longitudinal direction, and string portions along the width direction so as to intersect the longitudinal string A (horizontal string) is stretched at intervals in the longitudinal direction, and a net-like striking surface is formed in the frame (see, for example, Patent Document 1).

JP-A-6-269514

  By increasing the length of the vertical string and the horizontal string, and reducing the difference in the length of the vertical string aligned in the width direction and the difference in the length of the horizontal string aligned in the longitudinal direction, the ball rebound is good and the ball is hit. The sweet spot with small vibration at the time can be enlarged. However, if the shape of the frame is an ellipse or the like, the length of the vertical and horizontal strings passing through the end of the frame is the center of the frame when the string is folded along the outer peripheral surface of the curved frame. It becomes shorter than the length of the vertical string and the horizontal string passing through. Therefore, the area of the sweet spot is insufficient, and it is required to expand the area.

  The present invention has been made in view of such circumstances, and an object thereof is to enlarge the sweet spot of the racket without changing the shape of the frame.

  A main invention for achieving the above object includes a grip, an annular frame provided with a plurality of through holes penetrating from an inner peripheral surface to an outer peripheral surface, a shaft connecting the grip and the frame, and the frame. A grommet attached to an outer peripheral surface, and a plurality of cylindrical portions respectively inserted into the plurality of through holes provided in the frame, and a communication hole connecting the plurality of cylindrical portions and communicating with the inside of each cylindrical portion And a grommet having a grommet that allows a string to be inserted into the cylindrical portion and the communication hole, and in the longitudinal direction of the racket or on the striking surface of the racket When the direction orthogonal to the longitudinal direction is the first direction, the base portion attached to the first position in the first direction of the outer peripheral surface of the frame The portion of the base portion attached to the second position on the outer side in the first direction of the outer peripheral surface of the frame than the first position has a thickness from the inner peripheral surface to the outer peripheral surface. It is a racket characterized by being thick.

  Other features of the present invention will become apparent from the description of the present specification and the drawings.

  According to the racket and grommet of the present invention, the sweet spot of the racket can be enlarged without changing the shape of the frame.

It is the top view and side view of a racket for tennis. It is a perspective view of a racket. It is a figure explaining a mode that a string is stretched to a frame. It is explanatory drawing of the grommet attached to a frame 5A to 5C are explanatory diagrams of the first lower grommet of the present embodiment. 6A and 6B are explanatory views of a first lower grommet of a comparative example. It is a figure which shows the state which attached the 1st lower grommet to the flame | frame. 8A and 8B are views showing a modification of the first lower grommet.

=== Summary of disclosure ===
At least the following matters will become clear from the description of the present specification and the drawings.
That is, a grip, an annular frame provided with a plurality of through holes penetrating from an inner peripheral surface to an outer peripheral surface, a shaft connecting the grip and the frame, and a grommet attached to the outer peripheral surface of the frame. A plurality of cylindrical portions respectively inserted into the plurality of through holes provided in the frame, and a base portion provided with a plurality of communication holes that connect the plurality of cylindrical portions and communicate with the inside of each cylindrical portion. A racket having a grommet through which the string can be inserted into the cylindrical portion and the communication hole, and a longitudinal direction of the racket or a direction orthogonal to the longitudinal direction on the striking surface of the racket, Outer peripheral surface of the frame than the portion of the base portion attached to the first position in the first direction of the outer peripheral surface of the frame when the direction is one. The racket is characterized in that the base portion attached to the second position outside in the first direction is thicker from the inner peripheral surface to the outer peripheral surface than the first position. .
According to such a racket, the length of the string passing through the outer end portion (second position) in the first direction of the frame is changed to the center portion (first position in the first direction of the frame) without changing the shape of the frame. ) And the sweet spot can be enlarged.

In this racket, the shaft is bifurcated in a direction from the grip toward the frame when viewed from a direction orthogonal to the hitting surface of the racket, and the branched portion is along the hitting surface of the racket. A racket characterized by being bifurcated in a direction from the grip toward the frame when viewed from the direction.
According to such a racket, the base portion having a large thickness from the inner peripheral surface to the outer peripheral surface can be accommodated in the opening formed by the branching of the shaft. Air resistance can be suppressed. Further, by storing the base portion having a large thickness up to the opening portion of the shaft, the central portion in the first direction of the frame is passed to the length of the string at the position corresponding to the connection portion (opening portion) of the frame and the shaft. It can approach the length of the string. As a result, the sweet spot can be expanded to a position corresponding to the connection portion between the frame and the shaft.

In this racket, in the base portion of the grommet, a portion having a soft portion between the adjacent cylindrical portions, and a portion having a hard portion that is less elastically deformed than the soft portion between the adjacent cylindrical portions, Are alternately arranged, and the base portion closer to the second position than the first position than the soft portion of the base portion closer to the first position than the second position. The racquet is characterized in that the soft part of the is larger.
According to such a racket, different shot feelings are obtained when the string is folded at the base portion having the soft portion and when the string is folded at the base portion having the hard portion. In addition, when the string is folded back at the base portion having the soft portion, it is possible to absorb more vibration when the ball is hit back at a portion off the center of the frame.

A grommet attached to a racket having a grip, an annular frame provided with a plurality of through holes penetrating from an inner peripheral surface to an outer peripheral surface, and a shaft connecting the grip and the frame. A plurality of cylindrical portions respectively inserted into the plurality of through-holes provided in the base, and a base portion provided with a plurality of communication holes connecting the plurality of cylindrical portions and communicating with the inside of each cylindrical portion, The string can be inserted into the cylindrical portion and the communication hole, and when the first direction is a longitudinal direction of the racket or a direction perpendicular to the longitudinal direction on the striking surface of the racket, of the outer peripheral surface of the frame Outer side in the first direction than the first position in the outer peripheral surface of the frame, rather than a portion of the base portion attached to the first position in the first direction. Towards the site of the base unit attached to the second position, the thickness from the inner peripheral surface to the outer peripheral surface is thick, a grommet, wherein.
According to such a grommet, the length of the string passing through the outer end portion (second position) in the first direction of the frame is changed to the center portion (first position in the first direction of the frame) without changing the shape of the frame. ) And the sweet spot can be enlarged.

=== About Racket 1 ===
Hereinafter, as an example of the racket according to the present invention, a tennis racket will be described as an example.

  FIG. 1 is a plan view and a side view of a tennis racket (hereinafter referred to as a racket 1). The left figure is a plan view and the right figure is a side view. FIG. 2 is a perspective view of the racket 1, and FIG. 3 is a diagram illustrating a state in which the string 12 is stretched on the frame 11. The racket 1 includes a head 10 that is a part for hitting a ball, a grip 20 that is a part for a player to hold the racket 1, and a shaft 30 that integrally connects the head 10 and the grip 20. For the sake of explanation, the side where the head 10 is located in the longitudinal direction of the racket 1 is the front end side, and the side where the grip 20 is located is the rear end side. Further, on the striking surface of the racket 1 (that is, on a plane along the striking surface), the direction orthogonal to the longitudinal direction is defined as the width direction, and the direction orthogonal to the striking surface of the racket 1 is defined as the thickness direction.

  The head 10 includes a frame 11 having a substantially oval shape extending in the longitudinal direction, a string 12 stretched inside the frame 11, a grommet 40 attached to the outer peripheral surface 11 a of the frame 11, and a longitudinal direction of the frame 11. And a cover 14 attached to the front end portion. As shown in FIG. 3, a groove 111 is provided over the entire circumference of the frame 11 at the center in the thickness direction of the outer peripheral surface 11 a of the frame 11. The groove 111 is provided with a string hole 13 (corresponding to a through hole) that is a hole penetrating from the inner peripheral surface 11 b to the outer peripheral surface 11 a of the frame 11 and a hole for inserting the string 12. A plurality of string holes 13 are provided over the entire circumference of the frame 11.

  As shown in FIG. 3, the string 12 is stretched on the frame 11 via a grommet 40. The grommet 40 includes a plurality of tube portions 41 and a band-shaped base portion 42 that is provided with a plurality of communication holes 43 that connect the plurality of tube portions 41 and communicate with the hollow portions in each tube portion 41. The string 12 can be inserted into the cylindrical portion 41 and the communication hole 43 (details will be described later). In the grommet 40, the tip end portion (the end portion not connected to the base portion 42) of the cylindrical portion 41 is passed through the string hole 13 from the outer peripheral surface 11 a side of the frame 11, and the base portion 42 is a groove portion of the frame 11. It is attached to the outer peripheral surface 11 a of the frame 11 so as to be fitted into the frame 111. When the string 12 is stretched on the frame 11, the string 12 that passes from the inside of the frame 11 through the inside of the tubular portion 41 of the grommet 40 to the outside of the frame 11 extends along the base portion 42 of the grommet 40. The operation of being folded and passed through the next cylindrical portion 41 is repeated. As a result, a plurality of “vertical strings 121” that are portions of the strings 12 extending in the longitudinal direction are stretched inside the frame 11 at intervals in the width direction, and extend in the width direction so as to intersect the vertical strings 121. A plurality of “horizontal strings 122”, which are parts of the string 12, are stretched at intervals in the longitudinal direction to form a net-shaped hitting surface.

  As shown in the left diagram of FIG. 1, the shaft 30 has a first base end portion 31 that is a connection portion with the grip 20 and a left side in the width direction of the rear end portion of the frame 11 from the first base end portion 31. It has the 1st branch part 32a extended to an edge part, and the 2nd branch part 32b extended from the 1st base end part 31 to the right side edge part in the width direction among the rear-end parts of the flame | frame 11. That is, the shaft 30 is bifurcated toward the distal end side in the longitudinal direction (in the direction from the grip 20 toward the frame 11) when viewed from the thickness direction (direction orthogonal to the hitting surface of the racket 1). Therefore, a first opening 33 vacated in the thickness direction is formed by the rear end portion of the frame 11 and the first branch portion 32a and the second branch portion 32b.

  Further, as shown in the right diagram of FIG. 1, the first branch portion 32 a and the second branch portion 32 b are respectively connected to the second base end portion 34, which is a connection portion with the first base end portion 31, and the second base end portion. A third branch portion 35a extending from the portion 34 to the front end portion in the thickness direction of the rear end portion of the frame 11, and a rear side in the thickness direction of the rear end portion of the frame 11 from the second base end portion 34. And a fourth branch part 35b extending to the end part. That is, the first branch portion 32a and the second branch portion 32b are bifurcated toward the front end side in the longitudinal direction when viewed from the width direction (the direction along the hitting surface of the racket 1). Therefore, a second opening 36 vacated in the width direction is formed by the rear end portion of the frame 11 and the third branch portion 35a and the fourth branch portion 35b.

=== About Grommet 40 ===
FIG. 4 is an explanatory diagram of five grommets 40a to 40e attached to the frame 11. FIGS. 5A to 5C are explanatory diagrams of a first lower grommet 40d of the present embodiment, and FIGS. FIG. 7 is an explanatory view of a first lower grommet 40d ′ of a comparative example, and FIG. 7 is a diagram showing a state in which the first lower grommet 40d is attached to the frame 11. 5A and 6A are side views of the first lower grommets 40d and 40d ′, and FIGS. 5B and 6B are cross-sectional views when the first lower grommets 40d and 40d ′ are cut at the center in the thickness direction. FIG. 5C is a top view of the first lower grommet 40d.

  In the racket 1 of this embodiment, as shown in FIG. 4, five grommets 40 a to 40 e are attached to the outer peripheral surface 11 a of the frame 11. As described above, each of the grommets 40 a to 40 e includes a plurality of cylindrical portions 41 that are inserted into the string holes 13 provided in the frame 11, and a band-shaped base portion 42 that connects the plurality of cylindrical portions 41. . By stringing the string 12 on the frame 11 through the grommet 40, it is possible to protect the string 12 and to attenuate the vibration at the time of hitting the ball.

  For the sake of explanation, the grommet attached to the front end in the longitudinal direction of the frame 11 is referred to as an upper grommet 40a, and the grommet attached to the right side in the width direction of the frame 11 is referred to as a right grommet 40b. A grommet attached to the left side is called a left grommet 40c, and a grommet attached to the right side in the width direction of the rear end in the longitudinal direction of the frame 11 is called a first lower grommet 40d and is attached to the left side in the width direction. This grommet is referred to as a second lower grommet 40e. In addition, you may integrate the cover 14 attached to the front-end | tip part of the flame | frame 11, and the upper grommet 40a.

<< first lower grommet 40d, second lower grommet 40e >>
Hereinafter, the first lower grommet 40d and the second lower grommet 40e will be described in detail. However, the first lower grommet 40d and the second lower grommet 40e are symmetrical in the width direction, and the second lower grommet 40e is obtained by inverting the first lower grommet 40d in the width direction. Therefore, the first lower grommet 40d will be described as an example.

  In the first lower grommet 40d, as shown in FIG. 5A, six cylindrical portions 41 protrude from the inner peripheral surface 42b (surface on the side in contact with the frame 11) of the base portion 42. The six cylindrical portions 41 are arranged at intervals in the width direction in accordance with the positions of the string holes 13 of the frame 11. For the sake of explanation, the first cylinder part 411, the second cylinder part 412,..., And the sixth cylinder part 416 are called in order from the cylinder part 41 on the left side in the width direction.

  On the other hand, the outer peripheral surface 42a of the base portion 42 has an uneven shape, and the outer peripheral surface 42a between every other cylindrical portion 41 among the cylindrical portions 41 adjacent in the width direction protrudes. The part from which the outer peripheral surface 42 a protrudes is called a convex part 45, and the part that does not protrude is called a concave part 46. Specifically, between the first tube portion 411 and the second tube portion 412, between the third tube portion 413 and the fourth tube portion 414, between the fifth tube portion 415 and the sixth tube portion 416, The convex portion 45, and the concave portion 46 is between the second cylindrical portion 412 and the third cylindrical portion 413 and between the fourth cylindrical portion 414 and the fifth cylindrical portion 415.

  Further, on the outer peripheral surface 42a of the base portion 42, a groove portion 44 is provided at the central portion in the thickness direction, similarly to the upper grommet 40a shown in FIG. The groove portion 44 extends from one end to the other end in the width direction of the base portion 42. In order to represent this groove part 44, the external shape of the both sides in the thickness direction of the base part 42 is shown with a dotted line in FIG. 5B. In addition, the base portion 42 has six communication holes 43 respectively communicating with the hollow portions in the six cylinder portions 411 to 416, that is, six communication holes 43 penetrating from the inner peripheral surface 42 b to the outer peripheral surface 42 a of the base portion 42. One is provided. Since the opening portion of the communication hole 43 is provided in the groove portion 44, the string 12 coming out of the communication hole 43 is folded back at the groove portion 44 in the outer peripheral surface 42 a of the base portion 42. In addition, since the depth of the groove part 44 provided in the outer peripheral surface 42a of the base part 42 is substantially constant, the groove part 44 which is the folding | turning part of the string 12 also has uneven | corrugated shape.

  The inner peripheral surface 42b of the base portion 42 is curved in accordance with the shape of the portion of the outer peripheral surface 11a of the frame 11 to which the first lower grommet 40d is attached (that is, the right half of the rear end portion in the longitudinal direction of the frame 11). . The outer peripheral surface 42a of the base part 42 is also curved. However, the base portion 42 of the first lower grommet 40d of the present embodiment is closer to the right side in the width direction, that is, the portion attached to the outer side in the width direction of the frame 11 from the inner peripheral surface 42b to the outer peripheral surface 42a. The thickness up to is thick. Specifically, as shown in FIG. 5A, the length (d1 to d5) from the inner peripheral surface 42b to the outer peripheral surface 42a in the direction orthogonal to the inner peripheral surface 42b is longer. Therefore, the outer peripheral surface 42a of the base portion 42 has a lower degree of curvature than the inner peripheral surface 42b.

  In addition, since the outer peripheral surface 42a of the base portion 42 has an uneven shape, strictly speaking, the third cylindrical portion is larger than the thickness d1 between the first cylindrical portion 411 and the second cylindrical portion 412 (the convex portion 45). The thickness d3 between 413 and the fourth cylinder part 414 (convex part 45) is thicker, and the thickness d5 between the fifth cylinder part 415 and the sixth cylinder part 416 (convex part 45) is the thickest. The thickness d4 between the fourth cylinder portion 414 and the fifth cylinder portion 415 (recess 46) is thicker than the thickness d2 between the second cylinder portion 412 and the third cylinder portion 413 (recess 46). It has become. However, in the portion of the base portion 42 on the right side in the width direction from the sixth cylindrical portion 416, the base portion 42 does not protrude from the frame 11 or the shaft 30 when the first lower grommet 40d is attached to the frame 11 (FIG. 7). Further, the thickness from the inner peripheral surface 42b to the outer peripheral surface 42a is gradually reduced toward the right side in the width direction. By doing so, the air resistance at the time of swinging of the racket 1 can be suppressed.

  Further, the first lower grommet 40d is formed by two-color molding using a hard resin and a softer and more easily elastically deformable resin. An example in which the two-color molding resin is Pebax (registered trademark) made of a polyether block amide copolymer, the hard resin is Pebax 7033, and the soft resin is Pebax 3533 is described as an example, but is not limited thereto. In FIG. 5, a portion formed of a hard resin is indicated by white, and a portion formed of a soft resin is indicated by cross hatching. The tube portion 41 is formed of a soft resin, and the base portion 42 is mainly formed of a hard resin. However, as shown in FIG. 5B, a soft portion 47 made of a soft resin is embedded in the convex portion 45. On the other hand, the recess 46 is formed of only a hard resin. Therefore, the convex portion 45 is more easily elastically deformed than the concave portion 46. That is, in the base portion 42, there are a portion having the soft portion 47 between the adjacent cylindrical portions 41 and a portion having a hard resin portion (hard portion) that is less elastically deformed than the soft portion 47 between the adjacent cylindrical portions 41. , Lined up alternately. Note that the convex portion 45 is farther away from the frame 11 having higher rigidity than the concave portion 46. From this, it can be said that the convex portion 45 is more easily elastically deformed than the concave portion 46.

When the ball collides with the hitting surface, the string 12 generates a force that causes the folded portion (the convex portion 45 and the concave portion 46) of the string 12 to be directed toward the inside of the frame 11. At this time, since the convex portion 45 is more easily elastically deformed than the concave portion 46, the above force can be absorbed. Therefore, when the string 12 is folded at the convex portion 45, the vibration at the time of hitting is absorbed and a soft hit feeling is obtained as compared with the case where the string 12 is folded at the concave portion 46. What is a soft shot feeling?
It is a feeling that the impact at the time of hitting is small and the direction of hitting can be reliably controlled. On the other hand, when the string 12 is folded at the concave portion 46, a harder hitting feeling can be obtained than when the string 12 is folded at the convex portion 45. The hard feel of a ball is a feeling that provides a light rebound, can obtain a fast ball speed, and can swing out the racket 1 quickly. That is, if the first lower grommet 40d of the present embodiment is used, a different feel at impact can be obtained only by changing the tension of the string 12. As shown in FIG. 5B, a column 48 made of a hard resin may be provided between the soft portions 47 arranged in the width direction in the convex portion 45. By doing so, it is possible to prevent the convex portion 45 from being excessively deformed by the string 12 at the time of hitting.

  By the way, while increasing the length of the vertical string 121 and the horizontal string 122, the difference in the length of the vertical string 121 aligned in the width direction and the difference in the length of the horizontal string 122 aligned in the longitudinal direction are reduced. A sweet spot with good resilience (good flying) and small vibration during hitting can be enlarged. The length of the vertical string 121 is the length from the folding point of the string 12 on the front end side in the longitudinal direction to the folding point on the rear end side, and the length of the horizontal string 122 is the folding of the string 12 on the left side in the width direction. It is the length from the point to the right turn point. When the frame 11 is substantially oval (annular) like the racket 1 of the present embodiment, if the string 12 is folded back along the outer peripheral surface 11a of the curved frame 11, the center portion in the width direction of the frame 11 The length of the vertical string 121 passing through the outer end is shorter than the length of the vertical string 121 passing through the outer end, and the outer end is compared with the length of the horizontal string 122 passing through the center in the longitudinal direction of the frame 11. The length of the horizontal string 122 that passes through is shortened. Therefore, only the center part of the frame 11 becomes a sweet spot, and its area is insufficient.

  Here, the first lower grommet 40d 'of the comparative example will be described with reference to FIG. Similarly to the first lower grommet 40d of the present embodiment, the first lower grommet 40d ′ of the comparative example has an outer peripheral surface 42a ′ having an uneven shape, and a groove 44 ′ at the center in the thickness direction of the outer peripheral surface 42a ′. Is provided. However, in the first lower grommet 40d ′ of the comparative example, unlike the first lower grommet 40d of the present embodiment, the thickness from the inner peripheral surface 42b ′ to the outer peripheral surface 42a ′ of the base portion 42 ′ is constant. Yes. Strictly speaking, the thickness D1 between the first cylinder part 411 and the second cylinder part 412 (convex part 45 ′) and between the third cylinder part 413 and the fourth cylinder part 414 (convex part 45 ′). The thickness D1 is equal to the thickness D1 between the fifth cylinder portion 415 and the sixth cylinder portion 416 (convex portion 45 ′), and between the second cylinder portion 412 and the third cylinder portion 413 (concave portion 46 ′). The thickness D2 is equal to the thickness D2 between the fourth cylinder portion 414 and the fifth cylinder portion 415 (recess 46 ′).

  Therefore, the outer peripheral surface 42a 'of the first lower grommet 40d' of the comparative example is greatly curved along the outer peripheral surface 11a of the frame 11, like the inner peripheral surface 42b '. Therefore, the opening portion of the communication hole 43 communicating with the inside of the cylindrical portion 41 on the right side in the width direction, that is, the folding position of the vertical string 121 passing through the cylindrical portion 41 on the right side in the width direction is located on the distal end side in the longitudinal direction. The difference between the folding position of the vertical string 121 passing through the first cylinder portion 411 and the folding position of the vertical string 121 passing through the sixth cylinder portion 416 is large. Therefore, when the string 12 is stretched on the frame 11 via the first lower grommet 40d ′ of the comparative example, the width direction of the frame 11 is the same as when the string 12 is folded along the outer peripheral surface 11a of the frame 11. The length of the vertical string 121 passing through the outer end is shorter than the length of the vertical string 121 passing through the center of the frame 11, and the length of the horizontal string 122 passing through the center in the longitudinal direction of the frame 11 is outside. The length of the horizontal string 122 passing through the end is shortened. Therefore, the sweet spot is not wide enough.

  On the other hand, in the first lower grommet 40d of the present embodiment, the portion of the base portion 42 on the right side in the width direction is thicker. That is, in the outer peripheral surface 11a of the frame 11, the outer peripheral surface 11a of the frame 11 is more than the portion of the base portion 42 attached to a certain position (corresponding to the first position) in the width direction (corresponding to the first direction). A portion of the base portion 42 attached to an outer position (corresponding to the second position) in the width direction than a certain position is thicker from the inner peripheral surface 42b to the outer peripheral surface 42a. The “thickness from the inner peripheral surface 42b of the base portion 42 to the outer peripheral surface 42a” is the length from the inner peripheral surface 42b to the outer peripheral surface 42a in the direction orthogonal to the inner peripheral surface 42b of the base portion 42. Hereinafter, it is also simply referred to as “the thickness of the base portion 42”.

  Therefore, the outer peripheral surface 42a of the first lower grommet 40d (base portion 42) of the present embodiment has a smaller degree of curvature than the outer peripheral surface 11a of the frame 11, and is an arc-shaped surface that is closer to a straight line. Therefore, in the first lower grommet 40d of the present embodiment, compared to the first lower grommet 40d ′ of the comparative example, the opening portion of the communication hole 43 communicating with the cylindrical portion 41 on the right side in the width direction, that is, the vertical string 121. The folding position of the vertical string 121 passing through the left cylindrical portion 41 (n-th cylindrical portion) in the width direction and the right cylindrical portion 41 in the width direction can be positioned at the rear end side in the longitudinal direction. The difference from the folding position of the vertical string 121 that passes through the (n + 1th cylinder portion) can be reduced. Therefore, the length of the vertical string 121 passing through the outer end portion in the width direction of the frame 11 can be made closer to the length of the vertical string 121 passing through the center portion in the width direction of the frame 11. As a result, even when the ball is hit in an area off the center of the frame 11, the difference from when the ball is hit at the center can be reduced, improving the rebound of the ball and vibration at the time of hitting the ball. Can be reduced (the same feel at impact can be obtained). That is, the sweet spot can be enlarged.

  In addition, at a portion where the base portion 42 of the first lower grommet 40d is thick, the distance from the highly rigid frame 11 is increased, and elastic deformation is likely to occur. For this reason, even if a force is generated that causes the string 12 to return to the inner side of the frame 11 when the ball collides with the hitting surface, the force can be absorbed by the thick part of the first lower grommet 40. . Also from this point, it can be said that even when a ball is hit in a region off the center of the frame 11, a close shot feeling can be obtained when the ball is hit at the center and the sweet spot can be enlarged.

  Specifically, the vertical string 121 extends from the folded position on the rear end side in the longitudinal direction of the vertical string 121 passing through the n-th cylinder part 41 of the first lower grommets 40d and 40d ′ of the present embodiment and the comparative example. The length until reaching the inner peripheral surface 11b of the frame 11 was compared as the effective length. As a result, in the first lower grommet 40d ′ of the comparative example, when the effective length of the vertical string 121 passing through the first cylinder part 411 is 100 (%), the second cylinder part 412 to the sixth cylinder part 416 are changed. The effective length of the passing vertical string 121 was 100 (%), 99 (%), 97 (%), 95 (%), and 91 (%) in this order. On the other hand, in the first lower grommet 40d of the present embodiment, when the effective length of the vertical string 121 passing through the first tube portion 411 is 100 (%), the second tube portion 412 to the sixth tube portion. The effective length of the vertical string 121 passing through 416 was 100 (%), 99 (%), 98 (%), 96 (%), and 93 (%) in this order. Also from this result, the length of the vertical string 121 passing through the outer end in the width direction of the frame 11 is greater in the first lower grommet 40d of the present embodiment than in the first lower grommet 40d ′ of the comparative example. It can be seen that the length of the vertical string 121 passing through the center is approached.

  Further, by using the first lower grommet 40d of the present embodiment, the sweet spot can be enlarged without changing the shape of the substantially elliptical frame 11. In addition, although the flame | frame 11 of this embodiment is a substantially ellipse shape whose curvature degree of the front-end | tip part and rear-end part of a longitudinal direction is small compared with an ellipse, it is not restricted to this. The shape of the frame 11 may be, for example, an accurate oval shape, a perfect circle shape, or a frame close to a quadrangle shape. However, the effect of aligning the lengths of the vertical strings 121 is greater when the present invention is applied to an accurate elliptical or perfect circular frame. In addition, an accurate oval or perfect circular frame has a lower air resistance when swinging than a frame that is nearly square.

  In addition, since the outer peripheral surface 11a of the frame 11 is located on the distal end side in the longitudinal direction as the outer side (right side) in the width direction, in the first lower grommet 40d ′ of the comparative example, the outer side in the width direction of the frame 11 The length of the vertical string 121 passing through is shorter. Therefore, in the first lower grommet 40d of this embodiment, the thickness of the base portion 42 is gradually increased toward the outer side (right side) in the width direction (except for the difference in thickness due to the uneven shape). . By doing so, the difference in the length of the vertical string 121 that passes through each of the first to sixth cylinder portions 411 to 416 can be reduced. Accordingly, it is possible to reduce the difference in the rebound and feel of the ball due to the difference in the hitting place in the frame 11, and to enlarge the sweet spot.

  The first lower grommet 40d has been described so far, but as described above, the second lower grommet 40e is obtained by inverting the first lower grommet 40d in the width direction. Therefore, by stretching the string 12 using the second lower grommet 40e, the length of the vertical string 121 passing through the left (outer) end in the width direction of the frame 11 is set to the center in the width direction of the frame 11. The length of the passing vertical string 12 can be approached, and the sweet spot can be further enlarged. Note that the first lower grommet 40d and the second lower grommet 40e may be integrated, but attachment to the frame 11 is easier if they are separated.

  Moreover, in the racket 1 of this embodiment, as shown in FIGS. 1 and 2, the shaft 30 is viewed from the direction orthogonal to the striking surface of the racket 1 (thickness direction) toward the distal end side in the longitudinal direction. Bifurcated into two parts, and further, the branched parts (first branch part 32a and second branch part 32b) are directed toward the front end side in the longitudinal direction when viewed from the direction (width direction) along the striking surface of the racket 1. It is bifurcated. Therefore, as shown in FIG. 7, a part of the first lower grommet 40d can be accommodated in the second opening 36 provided in the second branch part 32b of the shaft 30, that is, the third branch part 35a. The first lower grommet 40d can be sandwiched between the fourth branch portion 35b. In particular, by connecting the second branch portion 32b at the right end portion in the width direction of the rear end portion of the frame 11, the portion where the thickness of the base portion 42 is the thickest is accommodated in the second opening portion 36. Can do. Therefore, even if the base portion 42 is thickened, the area of the base portion 42 protruding from the frame 11 and the shaft 30 can be reduced, and an increase in air resistance when swinging the racket 1 can be suppressed.

  In the case of a racket in which the second branch portion 32b is not branched, as shown in FIG. 8A described later, the length in the width direction of the first lower grommet 40d is set to be longer than the length in the width direction of the first opening portion 33. Must be shortened. Therefore, by providing the second opening 36 by branching the shaft 30, the length in the width direction of the first lower grommet 40 d can be increased, and the length of more vertical strings 121 can be increased. it can. That is, the sweet spot can be expanded to a position corresponding to the connection portion between the frame 11 and the shaft 30.

  Even when the first lower grommet 40d is used, the length of the vertical string 121 passing through the outer end portion is still shorter than the length of the vertical string 121 passing through the center portion in the width direction of the frame 11. For this reason, the vibration is greater when the ball is hit in an area away from the center than when the ball is hit at the center of the frame 11. Therefore, the position closer to the outer end portion in the width direction of the frame 11 than the soft portion 47 (volume) of the portion (convex portion 45) of the base portion 42 attached at a position close to the center portion in the width direction of the frame 11 The soft portion 47 (volume) of the portion (convex portion 45) of the base portion 42 attached to is increased. By doing so, when the string 12 is folded back by the convex portion 45, vibrations when the ball is hit in a region off the center of the frame 11 can be absorbed more, and a softer feel at impact can be obtained. However, the present invention is not limited to this, and the size of the soft portion 47 included in the convex portion 45 may be constant. That is, it is possible to freely adjust the size of the soft portion 47 by the amount that the thickness of the base portion 42 is increased.

=== Modification ===
8A and 8B are diagrams showing a modification of the first lower grommet 40d. In the above embodiment, as shown in the right diagram of FIG. 1, the shaft 30 is bifurcated and viewed from the width direction, and the racket 1 provided with the second opening 36 is taken as an example. The racket 1 without the second opening 36 may be used. In this case, as shown in FIG. 8A, since the length in the width direction of the first lower grommet 40d must be shorter than the length in the width direction of the first opening 33, the cylinder provided in the first lower grommet 40d. The number of parts 41 is four. Also in this case, the length of the vertical string 121 passing through the third cylinder part 413 and the fourth cylinder part 414 can be increased by increasing the thickness of the portion of the base part 42 on the right side in the width direction. The sweet spot can be expanded.

  In the first lower grommet 40d (FIG. 5) of the above embodiment, the outer peripheral surface 42a of the base portion 42 is curved, and the opening portion of the communication hole 43 located on the right side (outside) in the width direction (the folding back of the string 12). However, the position is not limited to this. For example, as shown in FIG. 8B, the outer peripheral surface 42a of the base portion 42 where the first to sixth cylinder portions 411 to 416 are provided may not be curved. In this case, the folding position of the vertical string 121 passing through the first to sixth cylindrical portions 411 to 416 can be aligned, and the difference in length of the vertical string 121 passing through the first to sixth cylindrical portions 411 to 416 is made smaller. The sweet spot can be further expanded.

  In the above embodiment, the thickness of the base portion 42 of the first lower grommet 40d is gradually increased, but the present invention is not limited to this. For example, the thickness of the base portion 42 where the third to fourth cylinder portions 413 to 414 are provided is the same as the thickness of the base portion 42 where the first to second cylinder portions 411 to 412 are provided. Only the thickness of the portion of the base portion 42 where the fifth to sixth cylinder portions 415 to 416 are provided may be increased.

  In the said embodiment, although the thickness of the base part 42 of grommets 40a-40c other than the 1st lower grommet 40d and the 2nd lower grommet 40e is made constant, it is not restricted to this. For example, you may make the thickness of the both ends in the width direction among the base parts 42 of the upper grommet 40a thicker than the thickness of the center part in the width direction. By doing so, the difference in length of the vertical strings 121 arranged in the width direction can be further reduced. Further, for example, the thickness of both end portions in the longitudinal direction of the base portion 42 of the right portion grommet 40b and the left portion grommet 40c may be made thicker than the thickness of the central portion in the longitudinal direction. By doing so, the difference in length of the horizontal strings 122 arranged in the longitudinal direction can be reduced. In these cases, the thickness of the base portion 42 of the first lower grommet 40d and the second lower grommet 40e may be constant.

  In the grommets 40a to 40e of the above-described embodiment, the outer peripheral surface is formed in a concavo-convex shape and the soft portion 47 is provided in the convex portion 45, but this is not restrictive. For example, the outer peripheral surfaces of the grommets 40a to 40e may be provided with the soft portion 47 in the base portion 42 without making the outer peripheral surfaces uneven, or conversely, the outer peripheral surfaces of the grommets 40a to 40e may be provided with an uneven shape. You may make it not provide the soft part 47 in 45. FIG. Even in these cases, a different shot feeling can be obtained by changing how the string 12 is stretched. In addition, although different shot feelings cannot be obtained, the outer peripheral surfaces of the grommets 40a to 40e may not be uneven, and the soft portion 47 may not be provided in the base portion 42.

=== Other Embodiments ===
The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

  For example, in the above embodiment, a tennis racket is given as an example of the racket according to the present invention, but the present invention is not limited to this. For example, the present invention may be applied to squash rackets, badminton rackets, and the like. Moreover, in said embodiment, although the racket 1 with which the string 12 was stretched in the flame | frame 11 was mentioned as an example as a racket which concerns on this invention, it is not restricted to this, The racket with which the string 12 is not stretched But you can.

1 racket, 10 heads, 11 frames, 12 strings,
13 string hole (through hole), 14 cover, 20 grip,
30 shaft, 31 1st base end part, 32a 1st branch part, 32 2nd branch part,
33 1st opening part, 34 2nd base end part, 35a 3rd branch part, 35b 4th branch part,
36 2nd opening part, 40 grommet, 41 cylinder part, 42 base part, 43 communicating hole,
44 groove part, 45 convex part, 46 concave part, 47 soft part, 48 pillar,

Claims (4)

Grip,
An annular frame provided with a plurality of through holes penetrating from the inner peripheral surface to the outer peripheral surface;
A shaft connecting the grip and the frame;
A grommet attached to the outer peripheral surface of the frame, a plurality of cylindrical portions respectively inserted into the plurality of through holes provided in the frame, and the plurality of cylindrical portions connected to each other and in each cylindrical portion A base portion provided with a plurality of communication holes communicating with each other, and a grommet capable of inserting a string into the cylindrical portion and the communication hole;
A racket having
When the first direction is the longitudinal direction of the racket or the direction perpendicular to the longitudinal direction on the striking surface of the racket, it is attached to the first position in the first direction on the outer peripheral surface of the frame. From the inner peripheral surface to the outer peripheral surface, the base portion attached to the second position outside the first position of the outer peripheral surface of the frame in the first direction than the first position of the base portion. The thickness of the
A racket characterized by. The racket according to claim 1,
The shaft is bifurcated in a direction from the grip toward the frame when viewed from a direction orthogonal to the hitting surface of the racket,
The branched portion is bifurcated in the direction from the grip toward the frame as seen from the direction along the hitting surface of the racket,
A racket characterized by. The racket according to claim 1 or 2,
In the base portion of the grommet, a portion having a soft portion between adjacent cylindrical portions and a portion having a hard portion that is less elastically deformed than the soft portion between adjacent cylindrical portions are alternately arranged.
The soft part of the base part closer to the second position than the first position than the soft part of the base part close to the first position compared to the second position. Is bigger,
A racket characterized by. A grommet attached to a racket having a grip, an annular frame provided with a plurality of through holes penetrating from an inner peripheral surface to an outer peripheral surface, and a shaft connecting the grip and the frame,
A plurality of cylindrical portions respectively inserted into the plurality of through-holes provided in the frame; and a base portion provided with a plurality of communication holes that connect the plurality of cylindrical portions and communicate with the interior of each cylindrical portion. ,
A string can be inserted into the cylindrical portion and the communication hole,
The base portion attached to the first position in the first direction on the outer peripheral surface of the frame when the first direction is the longitudinal direction of the racket or the direction orthogonal to the longitudinal direction on the striking surface of the racket The portion of the base portion attached to the second position on the outer side in the first direction of the outer peripheral surface of the frame is more thicker from the inner peripheral surface to the outer peripheral surface than the first portion. Is thick,
Grommet characterized by.

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