JP2019187965A - Badminton racket - Google Patents

Abstract

To enable reduced diameter of a shaft while avoiding insufficient strength of the shaft.SOLUTION: A racket (10) of the present invention includes a frame (13) extending in an annular shape, a grip (11), and a shaft (12) that couples the frame and the grip. The shaft is formed to be solid by a fiber-reinforced resin. The shaft is formed to have a substantially circular shape in a cross sectional view in a plane orthogonal to an extension direction, and has a diameter dimension set to be 5.7 mm or more and 6.2 mm or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a badminton racket having a shaft.

  In the badminton, the player plays by swinging the racket and hitting the shuttle. For example, as disclosed in Patent Document 1, a badminton racket includes a shaft extending linearly by connecting a grip and an annular frame, and the frame and the shaft are made of fiber reinforced resin.

JP-A-11-262545

  In the racket shaft as disclosed in Patent Document 1, since the fiber reinforced resin is formed in a hollow cylindrical shape, the outer diameter is 6.4 mm or more in order to ensure both strength and performance. It was. On the other hand, it is desired to reduce the air resistance during swinging by increasing the shaft diameter and reducing the air resistance during swinging to increase the swing speed and improve swing performance. However, it has been difficult to ensure the strength to withstand actual play.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a badminton racket capable of reducing the diameter of the shaft while avoiding insufficient strength of the shaft.

  The badminton racket according to the present invention is a badminton racket including a frame extending in an annular shape, a grip, and a shaft connecting the frame and the grip, and the shaft is solidly formed of fiber reinforced resin. When viewed in cross-section on a plane orthogonal to the extending direction, the shape is approximately circular and the diameter dimension is set to 5.7 mm or more and 6.2 mm or less.

  According to this configuration, the shaft is formed of a solid fiber reinforced resin and formed to have the outer diameter as described above, thereby realizing both of ensuring the strength of the shaft and reducing the diameter of the shaft. Is possible. Thereby, while having the durability required for play, it is possible to reduce the air resistance in the shaft at the time of swing and improve the swing-out performance.

  In the present invention, the diameter dimension of the cross section may be set to about 6 mm. According to this configuration, it is possible to achieve a good balance between securing the strength of the shaft and improving the swing-out performance by reducing the diameter.

  According to the present invention, it is possible to reduce the diameter of the shaft while avoiding insufficient strength of the shaft.

It is a front view of the racket which concerns on embodiment of this invention. It is sectional drawing of the shaft cut | disconnected by the AA line of FIG. It is a figure which becomes the outer diameter dimension of the shaft of an Example and a comparative example, and shows the relationship with strength. It is explanatory drawing of experiment which measures the bending amount of the racket of an Example and a comparative example.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is a front view of a badminton racket according to an embodiment. In the following drawings, some components may be omitted for convenience of explanation.

  As shown in FIG. 1, a badminton racket (hereinafter referred to as “racquet”) 10 includes a grip 11 held by a player, a shaft 12 having one end connected to the grip 11 and extending in a linear direction, and a shaft 12 And an elliptical frame 13 connected to the other end of the frame. A string 14 is stretched inside the frame 13, and a striking surface 15 on which the shuttle is hit is formed by the string 14.

  In the claims and the description of the present specification, unless otherwise specified, as indicated by an arrow in FIG. 1, the side where the frame 13 is located in the longitudinal direction of the racket 10 is the front end side, and the grip 11 is The side where it is located is the rear end side. The direction orthogonal to the ball striking surface 15 is the front and back direction, and the direction perpendicular to the longitudinal direction on the ball striking surface 15 (that is, on the plane along the ball striking surface 15) is the left-right direction.

  The grip 11 and the shaft 12 are connected in a state where the shaft 12 is inserted into the grip 11 by a predetermined length and fixed by adhesion or the like.

  The frame 13 is formed of a hollow body having a predetermined thickness, and various cross-sectional shapes such as a circle, an ellipse, and a square can be adopted. The frame 13 is formed using internal pressure molding by expansion of a medium such as air. Although it can be exemplified that the frame 13 is filled with a predetermined foam material, the filling of the foam material may be omitted in a part or all of the frame 13. In the racket 10, the frame 13 and the shaft 12 are connected by a T-shaped joint (not shown) incorporated therein.

  FIG. 2 is a cross-sectional view of the shaft cut along line AA in FIG. As shown in FIG. 2, the shaft 12 is formed in a substantially circular shape when viewed in cross section on a plane orthogonal to the extending direction. The shaft 12 includes a core portion 12a located on the center side and a cylindrical portion 12b into which the core portion 12a is inserted to form the outer peripheral surface of the shaft 12, and is formed solid. Both the core portion 12a and the cylindrical portion 12b of the shaft 12 are formed of fiber reinforced resin including a reinforcing material made of fiber.

  In the present embodiment, the shaft 12 is formed so that its outer diameter is substantially the same from the front end to the rear end. In the shaft 12, the diameter D of the cross section is set to 5.7 mm or more and 6.2 mm or less, preferably 6.0 mm or more and 6.2 mm or less, and more preferably about 6.0 mm. . The reason will be described later.

  Next, a method for manufacturing the badminton racket according to the present embodiment will be described. First, a resin sheet (carbon sheet) of a thermosetting fiber reinforced resin (FRP: Fiber Reinforced Plastics) is prepared. The fiber reinforced resin is a semi-cured mixture of reinforcing fibers mixed with thermosetting resins such as epoxy and vinyl ester resins. Carbon fibers, glass fibers, organic fibers, ceramic fibers, etc. are used as the reinforcing fibers. Can be selected as appropriate. The resin sheet of this embodiment uses carbon fibers as reinforcing fibers.

  In order to form the shaft 12, a plurality of resin sheets are concentrically stacked on the mandrel and heated, and then the mandrel is removed to form the cylindrical portion 12 b. The orientation directions of the carbon fibers in the plurality of resin sheets are combined with appropriate directions such as the extending direction of the shaft 12, the direction orthogonal to the extending direction, and the direction oriented in a 45 ° direction with respect to the extending direction.

  Before and after the formation of the cylindrical portion 12b, a fiber reinforced resin made of the same material as the resin sheet is heat-formed into a round shaft shape to form the core portion 12a. Thereafter, the core portion 12a is inserted into the cylindrical portion 12b and fixed by means such as adhesion as required. The outer diameter of the core portion 12a and the inner diameter of the cylindrical portion 12b are set to be approximately the same size, and are formed so that no gap is generated between them.

  In the above, in forming the shaft 12, the core portion 12a and the cylindrical portion 12b are formed separately, but the solid shaft member having the outer diameter of the shaft 12 is prevented from being formed by thermoforming. Not a thing.

  Before and after the shaft 12 is formed, in order to form the frame 13, a plurality of resin sheets for the frame 13 are laminated to form a resin sheet cylinder wound in a cylindrical shape. Thereafter, a T-shaped joint having an adhesive attached is attached to both ends of the resin sheet for the frame 13 which are curved and butted together, and the joint is also attached to the distal end side of the cylindrical portion 12b of the shaft 12. After the frame 13 to which the joint is mounted in this way and the tip end side of the shaft 12 are placed in the mold, the mold is heated and pressurized to join the frame 13 and the shaft 12.

  Next, with reference to FIG. 3, an experiment conducted on the relationship between the outer diameter of the shaft and the amount of deformation will be described. FIG. 3 is a diagram showing the relationship between the outer diameter dimensions of the shafts of Examples and Comparative Examples and the amount of deformation. In FIG. 3, the horizontal axis indicates the outer diameter of the shaft, and the vertical axis indicates the amount of bending (relative value) of the shaft.

  In the experiment, as an example, a racket having a shaft having a solid cross-sectional shape as shown in FIG. 2 was manufactured as described in the above embodiment. In the experiment, as a comparative example, a racket in which the shaft of the example was changed to a hollow cylindrical shape was manufactured. The shafts of the examples were shaped after molding using a plurality of resin sheets that had a bending strength in the range of 1,200 MPa to 2,000 MPa and a flexural modulus of 130 GPa to 230 GPa. As long as the plurality of resin sheets are within the above range, the bending strength and the bending elastic modulus may be the same or different. The shaft of the comparative example was shaped after molding using a resin sheet that has a bending strength in the range of 1200 MPa to 2100 MPa and a flexural modulus of 160 GPa to 230 GPa.

  In each of the examples and comparative examples, a racket including a shaft having an outer diameter shown on the horizontal axis in FIG. 3 in a range of 5.6 mm to 7.0 mm was manufactured. The inner diameter of the shaft of the comparative racket was set to 2.8 mm.

  FIG. 4 is an explanatory diagram of an experiment for measuring the bending amount of the racket according to the example and the comparative example. As shown in FIG. 4, in this experiment, the racket grip is fixed, a predetermined load F is applied to the front end side of the frame, and the amount of deformation in the front and back direction at the front end of the frame is applied before the load F is applied. It was measured as the amount. In this measurement, the load F was applied to the racket of the comparative example in which the outer diameter dimension of the shaft was 6.4 mm in the measurement performed for each racket in which the outer diameter dimension of the shaft was changed as described above in the examples and comparative examples. The value of the amount of bending when added was 100, and the amount of bending of the rackets of other comparative examples and examples was measured as relative values. The measurement results are shown in the graph of FIG.

  As can be understood from the graph of FIG. 3, in both the example and the comparative example, the greater the outer diameter of the shaft, the smaller the amount of bending of the shaft becomes linear (linear), and the strength as the shaft. Becomes higher.

  Here, in the comparative example, a racket having an outer diameter of the shaft of 6.4 mm has been commercialized and has a track record of use, so that a racket with a bending amount of 100 or less satisfies the strength condition of the shaft. Become. Therefore, in the embodiment in which the shaft is solid, the strength condition is satisfied when the outer diameter of the shaft is 6.0 mm or more. In particular, when the outer diameter of the shaft is 6.0 mm or more and 6.2 mm or less, and more preferably when the outer diameter of the shaft is about 6.0 mm, the outer diameter of the shaft is secured while ensuring the strength of the shaft. Can be made thinner than the comparative example of 6.4 mm, and the swing resistance can be improved by reducing the air resistance during swing.

  Further, in the comparative example, the racket having an outer diameter of the shaft of 6.0 mm was proved that the racket was not able to play sufficiently due to insufficient strength. In the comparative example in which the outer diameter of the shaft is 6.0 mm, the bending amount is 123. Therefore, when the bending amount is larger than 123, the strength is insufficient. Therefore, in the embodiment, it is assumed that the strength condition is satisfied with the shaft having an outer diameter of 123 or less. In other words, in the embodiment, it is assumed that the strength condition is satisfied when the bending amount is 5.7 mm or more, which is sufficiently smaller than 123. With such an outer diameter, the swing resistance can be further improved by further reducing the air resistance during swing by further reducing the diameter.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, direction, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, the connection between the shaft 12 and the frame 13 is not limited to the joint described above, and other connection structures may be employed as long as the racket can be played in the same manner as the racket of the above embodiment.

  The present invention relates to a badminton racket capable of reducing the diameter of a shaft while avoiding insufficient strength of the shaft.

10 rackets (badminton rackets)
11 Grip 12 Shaft 13 Frame

Claims (2)

A badminton racket comprising an annularly extending frame, a grip, and a shaft connecting the frame and the grip,
The shaft is solidly formed of a fiber reinforced resin, and has a substantially circular shape and a diameter of 5.7 mm or more and 6.2 mm or less when viewed in cross section in a plane orthogonal to the extending direction. Badminton racket.   The badminton racket according to claim 1, wherein a diameter dimension of the cross section is set to about 6 mm.

Images