US20250367509A1 - Racket - Google Patents

Racket

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Publication number
US20250367509A1
US20250367509A1 US19/193,598 US202519193598A US2025367509A1 US 20250367509 A1 US20250367509 A1 US 20250367509A1 US 202519193598 A US202519193598 A US 202519193598A US 2025367509 A1 US2025367509 A1 US 2025367509A1
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US
United States
Prior art keywords
sample
equal
head
racket
frame
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
US19/193,598
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English (en)
Inventor
Wataru KIMIZUKA
Seiji Hayase
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sumitomo Rubber Industries Ltd
Original Assignee
Sumitomo Rubber Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sumitomo Rubber Industries Ltd filed Critical Sumitomo Rubber Industries Ltd
Publication of US20250367509A1 publication Critical patent/US20250367509A1/en
Pending legal-status Critical Current

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    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A63B49/10—Frames made of non-metallic materials, other than wood
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A63B49/10—Frames made of non-metallic materials, other than wood
    • A63B49/11—Frames made of non-metallic materials, other than wood with inflatable tubes, e.g. inflatable during fabrication
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A63B2049/0201—Frames with defined head dimensions
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A63B2049/0201—Frames with defined head dimensions
    • A63B2049/0203—Frames with defined head dimensions height
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A63B2049/0201—Frames with defined head dimensions
    • A63B2049/0204—Frames with defined head dimensions width
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2102/00—Application of clubs, bats, rackets or the like to the sporting activity ; particular sports involving the use of balls and clubs, bats, rackets, or the like
    • A63B2102/02—Tennis
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2102/00—Application of clubs, bats, rackets or the like to the sporting activity ; particular sports involving the use of balls and clubs, bats, rackets, or the like
    • A63B2102/04—Badminton
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2209/00—Characteristics of used materials
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2209/00—Characteristics of used materials
    • A63B2209/02—Characteristics of used materials with reinforcing fibres, e.g. carbon, polyamide fibres
    • A63B2209/023—Long, oriented fibres, e.g. wound filaments, woven fabrics, mats
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B60/00—Details or accessories of golf clubs, bats, rackets or the like
    • A63B60/42—Devices for measuring, verifying, correcting or customising the inherent characteristics of golf clubs, bats, rackets or the like, e.g. measuring the maximum torque a batting shaft can withstand

Definitions

  • the present specification discloses a racket that is suitable for use in, for example, tennis, soft tennis, squash, padel, and badminton.
  • a racket disclosed in the present specification includes a frame including a head.
  • a ratio (G2/G1) of a ball-hitting face stiffness value G2 to a side pressure stiffness value G1 is greater than or equal to 3.20.
  • FIG. 1 is a front view showing a tennis racket according to one embodiment.
  • FIG. 2 is a right-side view showing the tennis racket of FIG. 1 .
  • FIG. 3 is an exploded view showing part of the tennis racket of FIG. 1 in an enlarged manner.
  • FIG. 4 is a perspective view showing part of a manufacturing process of the racket of FIG. 1 .
  • FIG. 5 is an enlarged sectional view taken along line V-V of FIG. 1 .
  • FIG. 6 is an enlarged sectional view taken along line VI-VI of FIG. 5 .
  • FIG. 7 is an enlarged view showing part of a prepreg for first fiber reinforced layers of a head of FIG. 6 .
  • FIG. 8 is an enlarged view showing part of a prepreg for second fiber reinforced layers of the head of FIG. 6 .
  • FIG. 9 is a perspective view showing part of a high-elasticity layer of the head of FIG. 6 .
  • FIG. 10 is an enlarged view showing part of a prepreg for the high-elasticity layer of FIG. 9 .
  • FIG. 11 is a graph showing a relationship between a side pressure stiffness value and a ball-hitting face stiffness value of a frame of the tennis racket of FIG. 1 .
  • FIG. 12 is a front view showing a method of measuring the side pressure stiffness value of the frame of the tennis racket of FIG. 1 .
  • FIG. 13 A is a plan view showing a method of measuring the ball-hitting face stiffness value of the frame of the tennis racket of FIG. 1
  • FIG. 13 B is a front view thereof.
  • FIGS. 1 to 3 each show a tennis racket 2 .
  • the racket 2 includes a frame 4 , a grip 6 , an end cap 8 , a grommet 10 , and a string 12 .
  • the racket 2 can be used in regulation-ball tennis.
  • an arrow X represents the width direction of the racket 2
  • an arrow Y represents the axial direction of the racket 2
  • an arrow Z represents the thickness direction of the racket 2 .
  • the illustration of the grommet 10 and the string 12 is omitted.
  • the frame 4 includes a head 14 , a first throat 16 a, a second throat 16 b, and a shaft 18 .
  • the head 14 forms the contour of a face 20 (the face 20 will be described below in detail).
  • the front view shape of the head 14 is substantially an ellipse.
  • the major axis direction of the ellipse coincides with the axial direction Y of the racket 2 .
  • the minor axis direction of the ellipse coincides with the width direction X of the racket 2 .
  • reference sign Ch indicates the center of the head 14 .
  • the first throat 16 a extends from the head 14 .
  • the second throat 16 b extends from the head 14 .
  • the second throat 16 b merges with the first throat 16 a at a position away from the head 14 .
  • the shaft 18 extends from the position where the two throats 16 merge together.
  • the shaft 18 is continuous with the throats 16 .
  • a portion of the head 14 is a yoke 22 .
  • the frame 4 is hollow.
  • the main material of the frame 4 is a fiber reinforced resin.
  • the fiber reinforced resin includes a resin matrix and a large number of reinforcement fibers.
  • the frame 4 includes a plurality of fiber reinforced layers. The fiber reinforced layers will be described below in detail.
  • Examples of the base resin of the frame 4 include: thermosetting resins such as epoxy resin, bismaleimide resin, polyimide, and phenolic resin; and thermoplastic resins such as polyether ether ketone, polyether sulphone, polyether imide, polyphenylene sulfide, polyamide, and polypropylene.
  • Epoxy resin is a particularly suitable resin for the frame 4 .
  • reinforcement fibers of the frame 4 include carbon fibers, metal fibers, glass fibers, and aramid fibers. Carbon filament fibers are particularly suitable fibers for the frame 4 . Multiple types of fibers may be used in combination as the reinforcement fibers.
  • the head 14 includes a groove 24 .
  • the groove 24 is recessed from the outer peripheral surface of the head 14 .
  • the groove 24 is formed over substantially the entire periphery of the head 14 , except the yoke 22 .
  • the head 14 further includes a plurality of holes 26 .
  • the plurality of holes 26 are arranged over substantially the entire periphery of the head 14 .
  • the grip 6 is formed by a tape wound around the shaft 18 .
  • the grip 6 suppresses slip between a hand of a player and the racket 2 when the racket 2 is swung by the player.
  • the grommet 10 includes a base 28 and a plurality of pipes 30 .
  • the base 28 is belt-shaped.
  • Each pipe 30 is integrated with the base 28 .
  • Each pipe 30 rises from the base 28 .
  • a typical material of the grommet 10 is a synthetic resin that is softer than the frame 4 .
  • the tennis racket 2 may include a plurality of grommets 10 .
  • the number of pipes 30 of each grommet 10 may be one.
  • the grommet 10 is attached to the head 14 .
  • the base 28 In a state where the grommet 10 is attached to the head 14 , the base 28 is accommodated in the groove 24 .
  • the base 28 may partly protrude from the groove 24 .
  • the pipes 30 extend through the respective holes 26 .
  • the string 12 is stretched on the head 14 .
  • the string 12 is stretched in the width direction X and the axial direction Y.
  • the string 12 extends through the pipes 30 .
  • the string 12 forms a large number of threads 32 .
  • portions extending in the width direction X are referred to as transverse threads 32 a .
  • portions extending in the axial direction Y are referred to as longitudinal threads 32 b.
  • the face 20 is formed by a plurality of transverse threads 32 a and a plurality of longitudinal threads 32 b.
  • the face 20 generally extends along an X-Y plane.
  • FIG. 1 shows part of the face 20 .
  • the face 20 may be formed by two or more strings 12 .
  • a mandrel, a tube, and a plurality of prepregs 34 are prepared.
  • Each prepreg 34 is made from a plurality of reinforcement fibers arranged in parallel and a matrix resin.
  • the mandrel is inserted into the tube.
  • the prepregs 34 are sequentially wound around the tube.
  • the prepregs 34 have a tubular shape.
  • FIG. 4 shows a tubular prepreg 34 p and a sheet-shaped prepreg 34 s. In FIG. 4 , the illustration of the mandrel and the tube is omitted.
  • the prepreg 34 s By rotating the mandrel, the prepreg 34 s is wound around the prepreg 34 p. As a result of the winding, the prepreg 34 s has a tubular shape, and thus a layered body 36 is obtained. Another prepreg 34 is further wound around the layered body 36 as necessary. A plurality of sheet-shaped prepregs 34 s may be layered one on top of another, which may be then wound around the mandrel or the prepreg 34 p. In FIG. 4 , an arrow A 1 represents the longitudinal direction of the layered body 36 .
  • the tube and the layered body 36 are set in a mold.
  • gas is injected into the tube, thereby inflating the tube.
  • the prepregs 34 are pressed against the cavity surface of the mold by the inflation.
  • the prepregs 34 are heated to cure the matrix resin.
  • a molded article is obtained by the curing.
  • the molded article has a reverse shape of that of the cavity surface.
  • the holes 26 are drilled in the molded article.
  • the molded article is further subjected to treatments such as surface polishing and painting, and thereby the frame 4 is obtained.
  • Components such as the grip 6 and the grommet 10 are attached to the frame 4 . Further, the string 12 is stretched on the frame 4 , and thus the tennis racket 2 is completed.
  • FIG. 5 is an enlarged sectional view taken along line V-V of FIG. 1 .
  • a cross section shown in FIG. 5 extends along a plane that is perpendicular to the axial direction of the frame 4 and that passes the center Ch of the head 14 .
  • the head 14 includes a first high-elasticity layer 37 a and a second high-elasticity layer 37 b (see also FIG. 2 ). Each high-elasticity layer 37 is positioned on the inner side in the head 14 in the thickness direction.
  • FIG. 6 is an enlarged sectional view taken along line VI-VI of FIG. 5 .
  • FIG. 6 shows the head 14 .
  • the head 14 includes a plurality of fiber reinforced layers 38 .
  • the head 14 includes a plurality of first fiber reinforced layers 38 a, a plurality of second fiber reinforced layers 38 b, and a plurality of third fiber reinforced layers 38 c.
  • the number of first fiber reinforced layers 38 a is five; the number of second fiber reinforced layers 38 b is five; and the number of third fiber reinforced layers 38 c is four.
  • the first fiber reinforced layers 38 a and the second fiber reinforced layers 38 b are arranged alternately in the thickness direction of the head 14 (i.e., the vertical direction in FIG. 6 ).
  • the first high-elasticity layer 37 a is formed by the plurality of third fiber reinforced layers 38 c.
  • the first high-elasticity layer 37 a is positioned on the inner side in the head 14 in the thickness direction (in FIG. 6 , the lower side).
  • the shape of the second high-elasticity layer 37 b is mirror-symmetrical to the shape of the first high-elasticity layer 37 a.
  • FIG. 7 shows a first prepreg 34 a for the first fiber reinforced layers 38 a.
  • the first prepreg 34 a includes a matrix 40 and a plurality of first reinforcement fibers 42 a arranged in parallel. Each first reinforcement fiber 42 a is inclined relative to the longitudinal direction A 1 .
  • an arrow ⁇ a represents an inclination angle (absolute value) of the first reinforcement fiber 42 a relative to the longitudinal direction A 1 .
  • the inclination angle ⁇ a is greater than or equal to 30° and less than or equal to 60°.
  • a reinforcement fiber 42 having an inclination angle of greater than or equal to 30° and less than or equal to 60° is referred to as a “bias-type reinforcement fiber”.
  • the first fiber reinforced layers 38 a include bias-type reinforcement fibers.
  • FIG. 8 shows a second prepreg 34 b for the second fiber reinforced layers 38 b .
  • the second prepreg 34 b includes the matrix 40 and a plurality of second reinforcement fibers 42 b arranged in parallel.
  • Each second reinforcement fiber 42 b is inclined relative to the longitudinal direction A 1 .
  • the direction in which each second reinforcement fiber 42 b is inclined is opposite to the direction (shown in FIG. 7 ) in which each first reinforcement fiber 42 a is inclined.
  • an arrow Ob represents an inclination angle (absolute value) of the second reinforcement fiber 42 b relative to the longitudinal direction A 1 .
  • the inclination angle Ob is greater than or equal to 30° and less than or equal to 60°.
  • Each second reinforcement fiber 42 b is a “bias-type reinforcement fiber”.
  • the second fiber reinforced layers 38 b include bias-type reinforcement fibers.
  • FIG. 9 shows part of the high-elasticity layer 37 .
  • the number of third fiber reinforced layers 38 c included in the high-elasticity layer 37 is four. These third fiber reinforced layers 38 c are obtained by folding a sheet-shaped third prepreg 34 c in such a manner that the sheet-shaped third prepreg 34 c is wound around itself.
  • FIG. 10 shows the third prepreg 34 c for the high-elasticity layer 37 .
  • the third prepreg 34 c includes the matrix 40 and a plurality of third reinforcement fibers 42 c arranged in parallel. Each third reinforcement fiber 42 c extends in the longitudinal direction Al. Each third reinforcement fiber 42 c has a zero inclination angle (absolute value) relative to the longitudinal direction A 1 . Each third reinforcement fiber 42 c may be slightly inclined relative to the longitudinal direction A 1 . In the present specification, a reinforcement fiber 42 having an inclination angle (absolute value) of less than or equal to 10° relative to the longitudinal direction A 1 is referred to as a “straight-type reinforcement fiber”.
  • the third fiber reinforced layers 38 c include straight-type reinforcement fibers. In other words, the high-elasticity layer 37 includes the straight-type reinforcement fibers.
  • a graph in FIG. 11 shows a relationship between a side pressure stiffness value G 1 and a ball-hitting face stiffness value G 2 of the frame 4 .
  • a straight line denoted by reference sign S 1 is expressed by a mathematical formula shown below.
  • the side pressure stiffness value G1 is relatively small, and the ball-hitting face stiffness value G2 is relatively large.
  • the side pressure stiffness value G1 is relatively small. According to findings obtained by the inventor of the present invention, in a vibration mode excited during a collision of the racket 2 with a tennis ball, the mode amplitude of the tennis ball is relatively large. Therefore, the speed of the tennis ball in the traveling direction at the end of the collision is high. In other words, the racket 2 whose side pressure stiffness value G1 is relatively small has excellent repulsion performance.
  • the ball-hitting face stiffness value G2 is relatively large. According to findings obtained by the inventor of the present invention, in a vibration mode excited during a collision of the racket 2 with a tennis ball, the mode amplitude of the tennis ball is relatively large. Therefore, the speed of the tennis ball in the traveling direction at the end of the collision is high. In other words, the racket 2 whose ball-hitting face stiffness value G2 is relatively large has excellent repulsion performance.
  • each high-elasticity layer 37 is positioned on the inner side in the head 14 in the thickness direction.
  • force in the thickness direction Z-direction
  • the force causes the head 14 to bend relative to the shaft 18 in the thickness direction.
  • the third reinforcement fibers 42 c are straight-type reinforcement fibers, due to the bending, a great tensile stress occurs on the third reinforcement fibers 42 c of the high-elasticity layer 37 .
  • the third reinforcement fibers 42 c suppress the bending.
  • the high-elasticity layer 37 contributes to achieving a large ball-hitting face stiffness value G 2 .
  • FIG. 12 shows a method of measuring the side pressure stiffness value G 1 .
  • the tennis racket 2 is placed on a base 44 , which is a rigid body.
  • the width direction X of the racket 2 coincides with the vertical direction.
  • the axial direction Y of the racket 2 coincides with the horizontal direction.
  • a plate 46 which is a rigid body, is lowered, and thereby a load is applied to the racket 2 .
  • a displacement (cm) of the plate 46 is measured from when the load is 25 kgf to when the load is 50 kgf.
  • the side pressure stiffness value G1 is calculated by dividing the load difference 25 kgf by the displacement (cm).
  • the side pressure stiffness value G1 is measured in a state where the string 12 is removed from the frame 4 .
  • the side pressure stiffness value G 1 is preferably less than or equal to 90 kgf/cm, more preferably less than or equal to 80 kgf/cm, and particularly preferably less than or equal to 75 kgf/cm.
  • the side pressure stiffness value G1 of the tennis racket 2 suitable for practical use is greater than or equal to 20 kgf/cm.
  • FIGS. 13 A and 13 B show a method of measuring the ball-hitting face stiffness value G2.
  • a first bar 48 a, a second bar 48 b, and a third bar 48 c are prepared.
  • the material of these bars 48 is steel.
  • Each bar 48 has a circular cross-sectional shape having a radius of 10.0 mm.
  • Each bar 48 extends in the width direction X.
  • the distance between the first bar 48 a and the third bar 48 c in the axial direction is 170 mm
  • the distance between the third bar 48 c and the second bar 48 b in the axial direction is 170 mm.
  • the first bar 48 a is positioned at the top of the head 14 .
  • the racket 2 is placed on the first bar 48 a and the second bar 48 b.
  • the width direction X and the axial direction Y of the racket 2 coincide with the horizontal direction.
  • the third bar 48 c is lowered, and thereby a load is applied to the tennis racket 2 .
  • a displacement (cm) of the third bar 48 c is measured from when the load is 25 kgf to when the load is 50 kgf.
  • the ball-hitting face stiffness value G2 is calculated by dividing the load different 25 kgf by the displacement (cm).
  • the ball-hitting face stiffness value G2 is measured in a state where the string 12 is removed from the frame 4 .
  • the ball-hitting face stiffness value G 2 is preferably greater than or equal to 100 kgf/cm, more preferably greater than or equal to 200 kgf/cm, and particularly preferably greater than or equal to 250 kgf/cm.
  • the ball-hitting face stiffness value G2 of the tennis racket 2 suitable for practical use is less than or equal to 500 kgf/cm.
  • an arrow Lh represents the length of each high-elasticity layer 37 in the axial direction.
  • the length Lh is a distance in the axial direction from a top Pt of the head 14 to an end Ed of the high-elasticity layer 37 .
  • the length Lh is preferably greater than or equal to 170 mm, more preferably greater than or equal to 250 mm, and particularly preferably greater than or equal to 340 mm for the reason that a large ball-hitting face stiffness value G2 can be achieved with such setting of the length Lh.
  • an arrow Tf represents the thickness of the frame 4
  • an arrow Wf represents the width of the frame 4
  • a ratio (Tf/Wf) of the thickness Tf to the width Wf is preferably greater than or equal to 2.0. If the ratio (Tf/Wf) of the tennis racket 2 is within this range, a large ratio (G2/G1) can be readily achieved. In light of this, the ratio (Tf/Wf) is more preferably greater than or equal to 2.2, yet more preferably greater than or equal to 2.4, and particularly preferably greater than or equal to 2.8. The ratio (Tf/Wf) of the tennis racket 2 suitable for practical use is less than or equal to 4.0.
  • the thickness Tf is preferably greater than or equal to 20.0 mm, more preferably greater than or equal to 26.0 mm, yet more preferably greater than or equal to 28.5 mm, and particularly preferably greater than or equal to 33.0 mm for the reason that a large ratio (G2/G1) can be readily achieved with such setting of the thickness Tf.
  • the thickness Tf of the tennis racket 2 suitable for practical use is less than or equal to 40.0 mm.
  • the ratio (G2/G1) is greater than or equal to 3.55.
  • the side pressure stiffness value G1 is relatively small, and the ball-hitting face stiffness value G 2 is relatively large. According to findings obtained by the inventor of the present invention, this tennis racket 2 has more excellent repulsion performance. In other words, the tennis racket 2 satisfying a mathematical formula shown below has more excellent repulsion performance.
  • the ratio (G2/G1) is greater than or equal to 3.90.
  • the side pressure stiffness value G 1 is relatively small, and the ball-hitting face stiffness value G 2 is relatively large. According to findings obtained by the inventor of the present invention, this tennis racket 2 has more excellent repulsion performance. In other words, the tennis racket 2 satisfying a mathematical formula shown below has more excellent repulsion performance.
  • the ratio (G2/G1) is greater than or equal to 4.10.
  • the side pressure stiffness value G1 is relatively small, and the ball-hitting face stiffness value G 2 is relatively large. According to findings obtained by the inventor of the present invention, this tennis racket 2 has extremely excellent repulsion performance. In other words, the tennis racket 2 satisfying a mathematical formula shown below has extremely excellent repulsion performance.
  • a tennis racket model for simulation was fabricated.
  • the specifications of the tennis racket model were as shown below.
  • Tennis racket models of samples 2 to 120 were fabricated in the same manner as the sample 1, except that the specifications of the tennis racket models were varied as shown in Tables 1 to 6 below.
  • the side pressure stiffness value G1 and the ball-hitting face stiffness value G2 of each sample were calculated by simulation. Further, a tennis ball was brought into collision with each sample, and the speed of the tennis ball when rebounding off the sample was calculated by simulation. The results are shown in Tables 1 to 6 below.
  • the ratio (G2/G1) is greater than or equal to 4.10.
  • the speed of the ball rebounding off each sample in Table 1 is greater than or equal to 5950 mm/s.
  • the ratio (G2/G1) is greater than or equal to 3.90 and less than 4.10.
  • the speed of the ball rebounding off each sample in Table 2 is greater than or equal to 5930 mm/s and less than 5950 mm/s.
  • the ratio (G2/G1) is greater than or equal to 3.55 and less than 3.90.
  • the speed of the ball rebounding off each sample in Table 3 is greater than or equal to 5900 mm/s and less than 5930 mm/s.
  • the ratio (G2/G1) is greater than or equal to 3.20 and less than 3.55.
  • the speed of the ball rebounding off each sample in Table 4 is greater than or equal to 5870 mm/s and less than 5900 mm/s.
  • the ratio (G2/G1) is less than 3.20.
  • the speed of the ball rebounding off each sample in Tables 5 and 6 is less than 5870 mm/s.
  • a racket including a frame including a head.
  • a ratio (G2/G1) of a ball-hitting face stiffness value G2 to a side pressure stiffness value G1 is greater than or equal to 3.20.
  • the head includes a high-elasticity layer that is positioned on an inner side in the head in a thickness direction of the head, the high-elasticity layer including straight-type reinforcement fibers.
  • the racket according to item 2 wherein the high-elasticity layer is present in a cross section that extends along a plane that is perpendicular to an axial direction of the frame and that passes a center of the head.
  • a ratio (Tf/Wf) of a thickness Tf of the frame to a width Wf of the frame is greater than or equal to 2.0.
  • the racket as described above is suitable also for use in, for example, soft tennis, squash, padel, and badminton.
  • the above descriptions are merely illustrative examples, and various modifications can be made without departing from the principles of the present invention.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Physical Education & Sports Medicine (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Laminated Bodies (AREA)
US19/193,598 2024-05-28 2025-04-29 Racket Pending US20250367509A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2024-086055 2024-05-28
JP2024086055A JP2025179357A (ja) 2024-05-28 2024-05-28 ラケット

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US20250367509A1 true US20250367509A1 (en) 2025-12-04

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US (1) US20250367509A1 (https=)
EP (1) EP4656257A1 (https=)
JP (1) JP2025179357A (https=)
CN (1) CN121016154A (https=)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0515617Y2 (https=) 1987-01-26 1993-04-23
JPH0687903B2 (ja) * 1989-12-05 1994-11-09 住友ゴム工業株式会社 テニスラケットフレーム
JP3820215B2 (ja) * 2002-12-20 2006-09-13 Ｓｒｉスポーツ株式会社 テニスラケット
JP2005065842A (ja) * 2003-08-21 2005-03-17 Sumitomo Rubber Ind Ltd ラケットフレーム
JP2005334160A (ja) * 2004-05-25 2005-12-08 Sri Sports Ltd テニスラケット

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