CN109069907B

CN109069907B - String set, string for longitudinal line and string for transverse line

Info

Publication number: CN109069907B
Application number: CN201780026198.2A
Authority: CN
Inventors: 大木胜敏; 千叶慎一郎; 小泽佳佑; 阪口巧
Original assignee: Yonex KK
Current assignee: Yonex KK
Priority date: 2016-04-27
Filing date: 2017-02-22
Publication date: 2021-08-06
Anticipated expiration: 2037-02-22
Also published as: EP3449983A1; KR20190022457A; US20190118045A1; MY191299A; JP2017196148A; CN109069907A; KR102668581B1; JP6812053B2; WO2017187742A1; EP3449983A4

Abstract

The invention provides a string set which can improve the light ball-picking performance and the ball-cutting performance in front of a net. The string group (20) is arranged as a vertical line and a horizontal line for the racket, and is provided with the following structure: the string comprises a first string (22) of small diameter stretched as either one of a vertical line and a horizontal line and having a small frictional force, and a second string (21) of large diameter stretched as the other of the vertical line and the horizontal line and having a larger frictional force than the first string. Thus, the functions are assigned to the first string and the second string, and the net front light ball-picking performance improved by increasing the surface friction force and the outer diameter of the string and the ball-cutting performance improved by decreasing the surface friction force and the outer diameter of the string are compatible.

Description

String set, string for longitudinal line and string for transverse line

Technical Field

The present invention relates to a string set stretched over a racket, a string for a vertical string, and a string for a horizontal string.

Background

In general, in a racket of a badminton, strings for vertical strings and strings for horizontal strings are stretched so as to cross each other, and form a front face of a shuttlecock. As each string, a structure is known in which a side wire is wound or braided around a core wire of a compound wire to coat the outside. Various proposals have been made for such strings to improve the functions such as durability (see, for example, patent document 1). For example, in the string described in patent document 1, the durability of the string is improved by adding metal powder such as titanium to the coating agent.

Patent document 1: japanese patent No. 3166031.

Disclosure of Invention

However, as a hitting ball of a badminton, a hitting ball called a "hit ball ahead (hairpin") and a hitting ball called a "cut ball" are known. The light ball-in-front is a shot for lightly bouncing back a shuttlecock (shuttelecock) dropped on the net to the opponent's court, and the cut ball is a shot for dropping a shuttlecock flying toward the top of the head to the net of the opponent's court by cutting the front surface of the racket. These shots have different functions for the string requirements, and it has become very difficult to improve the net-head hit performance (spin performance) and cut performance at the same time.

The present invention has been made in view of the above problems, and an object thereof is to provide a string set, strings for vertical strings, and strings for horizontal strings that can improve the light ball-picking performance and the ball-cutting performance in front of the net.

The string set of the present invention is stretched as a vertical string and a horizontal string with respect to a racket, and includes: the first string has a small diameter and is stretched as one of the vertical and horizontal lines, and the second string has a large diameter and is stretched as the other of the vertical and horizontal lines.

According to this structure, the friction force against the shuttlecock becomes large and the contact area becomes large because of the large diameter in which the surface friction force of the second string is large. Therefore, it becomes easy to improve the net-head light-hitting performance by rotating the rebounded shuttlecock when the net-head light-hitting is performed. Further, the friction force between the first string and the second string becomes small and the contact area becomes small due to the small diameter of the first string, which is small in surface friction force. Therefore, the first string and the second string are easy to move relatively when the ball is cut, so that the ball cutting performance is improved. In this way, the functions are assigned to the first strings and the second strings, and the net front light ball-picking performance improved by increasing the surface friction force and the outer diameter of the strings and the ball-cutting performance improved by decreasing the surface friction force and the outer diameter of the strings can be simultaneously achieved.

In the string set of the present invention, the first string is a string for the lateral line, and the second string is a string for the longitudinal line. According to this configuration, in addition to the net front light ball-picking performance and the ball-cutting performance, the outer diameter of the lateral string can be reduced to compensate for the deficiency of the hitting feeling (rebound feeling) caused by the increase in the outer diameter of the longitudinal string. Further, the edge breakage rate can be reduced by increasing the outer diameter of the chord for a longitudinal line, which is easily broken at the edge.

In the string set of the present invention, the frictional force when the second string moves relative to the first string is 2.2N or less. According to this structure, the second string becomes easy to move with respect to the first string, and the ball cutting performance can be improved.

In the chord group of the present invention, the outer diameter of the first chord is 94% or less of the outer diameter of the second chord. According to this configuration, the second string can be easily moved with respect to the first string, and the ball cutting performance can be improved, while the second string has a large diameter and the ball-picking performance in front of the net can be improved.

In the string set of the present invention, the surface friction of the racket front surface formed by the first strings and the second strings is 9N or more. According to this configuration, the frictional force on the front surface increases, and it becomes easy to impart rotation to the shuttlecock rebounded from the front surface.

In the chord group of the invention, the second chord has a coating film formed thereon, and at least an outer layer of the coating film of the second chord has a property of increasing grip with an increase in film thickness. According to this structure, the gripping force becomes large according to the film thickness of at least the outer layer of the coating film of the second string, and therefore, the surface friction force of the second string can be increased.

In the string set of the invention, at least the outer layer of the coating film of the second string is formed of polyurethane or rubber. With this configuration, the surface friction force of the second string can be increased with a simple configuration.

The string for a lateral string of the present invention is a string for a lateral string that crosses a racket and is stretched over a string for a longitudinal string, and is characterized in that the string for a lateral string has a smaller surface friction force and a smaller diameter than the string for a longitudinal string.

According to this configuration, the surface friction force of the string for the lateral line is reduced and the diameter is reduced as compared with the string for the longitudinal line, whereby the friction force between the strings is reduced and the contact area is reduced. Therefore, the strings for the vertical lines are easily moved relative to the strings for the horizontal lines during the ball cutting, and the ball cutting performance is improved. Even if the rotation is easily added by the string for the longitudinal cord having a large diameter and a large surface friction force, and the light ball-picking performance in front of the net is improved, the string for the longitudinal cord is sufficiently moved with respect to the string for the lateral cord, and the ball-cutting performance is not lowered. Thus, the functions of distributing the strings for the vertical strings and the strings for the horizontal strings can be achieved while achieving both the light ball-picking performance at the net front, which is improved by increasing the surface friction force and the outer diameter of the strings, and the ball-cutting performance, which is improved by decreasing the surface friction force and the outer diameter of the strings.

The string for a vertical string of the present invention is a string for a vertical string which is stretched across a racket and is provided on a string for a horizontal string, and is characterized in that the string for a vertical string has a larger surface friction force and a larger diameter than the string for a horizontal string.

According to this configuration, the friction force between the shuttlecock and the strings for vertical strings is increased and the contact area is increased by increasing the surface friction force and increasing the diameter of the strings for vertical strings as compared with the strings for horizontal strings. Therefore, it becomes easy to additionally rotate the shuttlecock rebounded when the shuttlecock is lightly picked in front of the net, thereby improving the performance of the light-picking shuttlecock in front of the net. Further, even if the ball cutting performance is improved by easily moving the strings for the longitudinal strings by the small-diameter strings for the transverse strings having a small surface friction, the ball cutting performance is not deteriorated because the surface friction of the strings for the longitudinal strings is sufficiently large. Thus, the functions of distributing the strings for the vertical strings and the strings for the horizontal strings can be achieved while achieving both the light ball-picking performance at the net front, which is improved by increasing the surface friction force and the outer diameter of the strings, and the ball-cutting performance, which is improved by decreasing the surface friction force and the outer diameter of the strings.

According to the present invention, the small-diameter first string having a small surface friction and the large-diameter second string having a large surface friction are used in combination, whereby the net front light ball-picking performance and the ball-cutting performance can be improved.

Drawings

Fig. 1 is a front view of a racket stretched with strings.

FIG. 2 is a diagram illustrating the front light ball picking performance and the ball cutting performance of the comparative example.

Fig. 3 is an explanatory diagram of the front light ball picking performance and the ball cutting performance of the present embodiment.

Fig. 4 is a cross-sectional view of the string of the present embodiment.

Fig. 5 is a diagram showing the relationship between the film thickness and the chord gauge of the polyurethane of the present embodiment.

Fig. 6 is a diagram showing a relationship between the horizontal line standard and the amount of movement of the vertical line in the present embodiment.

Fig. 7 is a diagram showing a relationship between the horizontal line standard and the frictional force when the vertical line moves in the present embodiment.

Fig. 8 is a diagram showing a relationship between a frictional force on a lateral line and a frictional force when a vertical line moves in the present embodiment.

Fig. 9 is an explanatory diagram of the hitting feel and the edge breakage rate of the present embodiment.

Fig. 10 is a diagram showing a relationship between the transverse wire standard of the present embodiment and the frictional force when the transverse wire passes through.

Fig. 11 is an explanatory view of the method for measuring the surface friction force according to the present embodiment.

Fig. 12 is an explanatory diagram of a method of measuring a frictional force when a vertical line moves according to the present embodiment.

Detailed Description

Next, a string set according to the present embodiment will be described with reference to the drawings. Fig. 1 is a front view of a racket stretched with strings. FIG. 2 is a diagram illustrating the front light ball picking performance and the ball cutting performance of the comparative example. Fig. 3 is an explanatory diagram of the front light ball picking performance and the ball cutting performance of the present embodiment. In addition, the same chord is used as the vertical line and the horizontal line in the comparative example, and different chords are used as the vertical line and the horizontal line in the present embodiment.

As shown in fig. 1, the vertical string 21 and the horizontal string 22 are stretched across the frame 53 of the racket 50 of the badminton racket to form a face 54 of the shuttlecock. The strings 21 for vertical lines and the strings 22 for horizontal lines intersect with each other so that the top and bottom of the strings alternate at the intersection position, and the strings 21 for vertical lines and the strings 22 for horizontal lines contact with each other only at the intersection position. When the shuttlecock is hit on the front face 54, the impact is dispersed to the strings 22 for the vertical strings and the strings 21 for the horizontal strings through the crossing positions, and the shuttlecock rebounds by the rebounding forces of the

strings

21 and 22.

As a ball hitting of a badminton, a ball hitting called a net head shot and a ball hitting called a cut ball are known. The net light shot is a shot that returns the shuttlecock through the front 54 of the racquet 50 to the net of the opponent's court with a light bounce. At this time, when the badminton ball is struck so that the front surface 54 of the racket 50 is substantially horizontal and bounces or rubs against the badminton ball, the bounced badminton ball is additionally rotated and returns to the opponent's court through the orbit immediately above. The cut ball is a ball that is hit by the face 54 in the form of a cut shuttlecock to the net of an opponent's court. At this time, the front 54 is obliquely touched against the shuttlecock, the strings 21 for the vertical lines are moved by the shuttlecock, and when the shuttlecock returns to the opponent's court along the track where the shuttlecock rapidly falls, the shuttlecock is additionally rotated.

However, as in the comparative example shown in fig. 2A, the

same strings

41 and 42 are generally used as the vertical strings and the horizontal strings of the racket. At this time, as a factor for determining the performance of the front-of-net light ball, the spin addition at the time of hitting the front-of-net light ball becomes important. The rotation is determined by the friction between the surface of the

strings

41, 42 and the cork leather of the shuttlecock. Therefore, in order to improve the front-net light-weight ball-picking performance, it is important to increase the string specifications (outer diameters) and the surface friction of the

strings

41 and 42. Therefore, if the string specifications and the surface friction of the

strings

41 and 42 are increased in order to improve the net front light ball-picking performance, the string 41 for the longitudinal string becomes difficult to move, and the ball-cutting performance is degraded.

On the other hand, as shown in fig. 2B, it is important that the string 41 for a longitudinal line easily moves as a factor for determining the chipping performance. The ease of movement of the strings 41 for the longitudinal line is determined by the frictional force between the strings and the contact area. Therefore, in order to improve the chipping performance, it is important to reduce the string specifications and the surface friction of the

strings

41 and 42 are reduced in order to improve the chipping performance, it becomes difficult to impart rotation to the shuttlecock and reduce the net head light-weight performance.

As described above, if the string specifications and the frictional force of the

strings

41 and 42 are increased, the net front light ball-picking performance is improved and the ball-cutting performance is lowered. Further, if the string specifications and the surface friction of the

strings

41, 42 are reduced, the ball cutting performance is improved and the net front light ball picking performance is reduced. Since there is a trade-off relationship between the front cut performance and the cut performance, it is difficult to improve both the front cut performance and the cut performance when the

same strings

41 and 42 are used as the lateral and longitudinal lines. In addition, the striking feel deteriorates when the string gauge is increased, and on the contrary, the edge is easily broken when the string gauge is decreased, and the tension becomes difficult when the surface friction is increased.

Therefore, in the present embodiment, the following configuration is provided: the string 21 for the longitudinal line with a large diameter (second string) and the string 22 for the transverse line with a small diameter (first string) having a large surface friction are assigned with the pre-net light ball-picking performance and the ball-cutting performance. Then, the disadvantage caused by increasing the chord length and the surface friction force of the string 21 for the vertical cord is improved by decreasing the chord length and the surface friction force of the string 22 for the horizontal cord. Conversely, the disadvantage caused by the decrease in the chord length and the surface friction force of the lateral string 22 is improved by the increase in the chord length and the surface friction force of the longitudinal string 21.

Specifically, as shown in fig. 3A, the string group 20 of the present embodiment includes a vertical string 21 having a larger diameter and a smaller diameter, and a horizontal string 22 having a larger surface friction than the horizontal string 22 and a smaller surface friction than the vertical string 21. Since the vertical string 21 is formed to have a large diameter with a large surface friction, the friction and contact area between the surface of the vertical string 21 and the shuttlecock become large, and the shuttlecock is easily rotated. By using the large-diameter strings 21 having a large surface friction as the longitudinal strings, the net front light-weight ball-picking performance can be improved even when the small-diameter strings 22 having a small surface friction are used as the lateral strings.

On the other hand, as shown in fig. 3B, since the string 22 for the lateral line has a small diameter with a small surface friction, the contact area and the surface friction between the

strings

21 and 22 are small, and the string 21 for the longitudinal line is easily moved relative to the string 22 for the lateral line. The vertical string 21 moves largely by the shuttlecock, and the force restored to the vertical string 21 acts on the shuttlecock, so that additional cutting is easy. By using the small-diameter strings 22 having a small surface friction as the transverse lines, the ball cutting performance can be improved even when the large-diameter strings 22 having a large surface friction are used as the longitudinal lines.

Further, the deficiency of the hitting feeling (rebound feeling) caused by increasing the string size of the vertical string 21 is compensated for by decreasing the string size of the horizontal string 22. On the other hand, the edge that is generated by the string gauge of the lateral string 22 being small is easily broken, and the string gauge of the vertical string 21 that is particularly easily broken is increased to compensate for this. Further, the difficulty in stretching due to the increase in the surface friction force of the string 21 for the vertical string is compensated for by reducing the surface friction force of the string 22 for the horizontal string.

Next, the string set of the present embodiment will be described in detail. Fig. 4 is a sectional view of the string of the present embodiment. The cross-sectional structure of the chord according to the present embodiment is not limited to the structure shown in fig. 4, and can be appropriately changed.

As shown in fig. 4, a coating film 16 is formed around a linear structure 13 composed of a core wire 11 and

side wires

12a and 12b to form a string 21. The

side wires

12a and 12b are woven around the core wire 11 of the compound wire to form a linear structure 13. The

side wires

12a and 12b are woven so that the core wire 11 is covered with 8 sets in the S direction and 8 sets in the Z direction, with a plurality of side wires forming 1 set.

Around the linear structure 13, after the inside is coated with polyamide or the like, the outer layer is coated with polyurethane to form a coating film 16 having a predetermined film thickness. That is, the coating film 16 has a two-layer structure of an inner coating layer (inner layer) and an outer coating layer (outer layer), and the outer coating layer has a higher frictional force (coefficient of friction) than the inner coating layer. Further, the coating film 16 may be formed of only polyurethane. In the following description, the film thickness t of the coating film 16 of the string 21 indicates the thickness of the linear structure 13 from the outermost surface.

Although not shown in detail, the lateral string 22 is formed substantially the same as the longitudinal string 21 except that the coating film is formed only of polyamide and the outer diameter of the linear structure is small. The string 22 for the lateral line is different from the string 21 for the longitudinal line, and the surface friction force is smaller than that of the string 21 for the longitudinal line because the outer layer of the coating film is also made of polyamide. The material of the core wire and the side wire of the string 21 for the longitudinal string and the string 22 for the transverse string is not particularly limited, and for example, polyamide, polyester, or the like is used.

Next, the front light ball hitting performance will be described. Fig. 5 is a diagram showing the relationship between the film thickness and the chord gauge of the polyurethane of the present embodiment. In fig. 5, the horizontal axis represents the thickness of the polyurethane film in the outer layer of the coating film, and the vertical axis represents the chord gauge. Further, the coating film is formed of polyurethane and polyamide as described above, and the thickness of the polyurethane in the outer layer can be increased by decreasing the thickness of the polyamide in the inner layer. Further, the gauge indicates the outer diameter at 25 pounds of traction.

As shown in fig. 5, when the surface friction of the string is changed and the trial hitting of the pre-net flick ball is repeated, the following is known: players feel that the surface friction of the string is more than 9N, which makes it easier for them to rotate on the shuttlecock, and more than 12N, which makes it easier for them to rotate on the shuttlecock. Therefore, the results shown in the figure were obtained when the relationship between the coating film thickness and the chord specification where the surface friction of the chord was 9N or more and 12N or more was examined. Here, the rotation region will be described as a region where the surface friction of the string is 9N or more, and the high rotation region will be described as a region where the surface friction of the string is 12N or more.

When the thickness of the polyurethane film shown on the abscissa of FIG. 5 is 0 μm, a range R1 having a chord gauge of about 0.80mm to 0.94mm is a rotation region, and a range R2 having a chord gauge of about 0.94mm or more is a high rotation region. When the thickness of the polyurethane film is 8 μm, the region R3 having a chord gauge of about 0.50mm to 0.65mm is a rotation region, and the region R4 having a chord gauge of about 0.65mm or more is a high rotation region. That is, as the thickness of the polyurethane film increases, the region in which additional rotation is easily applied becomes wider, and a surface friction force of 9N or more can be obtained even if the chord gauge is small. Additionally, the gauge indicates the outer diameter at 25 pounds of traction.

When the chord length shown by the vertical axis of FIG. 5 is 0.50mm, the range R5 where the film thickness is 8 μm or more is the rotation region. When the chord gauge is 0.80mm, the region R6 where the thickness of the polyurethane film is 0 μm to 2 μm is the rotation region, and the region R7 where the thickness of the polyurethane film is 2 μm or more is the high rotation region. That is, as the string gauge becomes larger, the region in which additional rotation is easily applied becomes wider, and a surface friction force of 9N or more can be obtained even if the film thickness of polyurethane is small. As described above, the larger the thickness and the chord gauge of the polyurethane, the wider the region in which the rotation is easily applied. The surface friction of the front surface 54 of the racket 50 formed of the strings 22 for the lateral strings and the strings 21 for the vertical strings is easily affected by the surface friction of the string (second string) having a larger surface friction.

When the film thickness of the polyurethane is large, the surface friction of the string is increased by increasing the grip on the shuttlecock. Further, when the string size is large, the surface friction of the string is increased by making the contact area of the surface of the string with the cork leather of the shuttlecock large.

As described above, in the present embodiment, by adjusting the film thickness and the chord specification of the polyurethane, an appropriate surface friction force is applied to the surface of the chord. The frictional force of the string IS measured, for example, by sliding a weight having cork leather adhered to the contact surface on the string surface stretched on the racket, using Autograph AG-IS (Shimadzu corporation).

Specifically, as shown in fig. 11, a racket 50 with

strings

21 and 22 stretched longitudinally and transversely is placed on a horizontal table 60, and a plate-like weight 32(1kg) with cork leather 31 is loaded. One end of the wire 33 IS attached to the weight 32, and the other end of the wire 33 IS attached to a chuck 72 of a tensile tester 70(Autograph AG-IS) via a pulley 71. The weight 32 on the surface of the string 21 is stretched by the raising of the collet 72, and the frictional force generated between the

strings

21, 22 and the cork leather 31 is measured as the tensile force of the tensile tester 70. That is, the surface friction of the string 21 is the friction when the weight 32 with the cork leather 31 and the weight of 1kg slides against the

strings

21 and 22.

Next, in order to select an optimum material, the surface friction force of the string was measured by forming the outer layer of the coating film with polyamide added with terpene resin, polyurethane excellent in production stability, and 3 kinds of rubber excellent in frictional property, and compared with the surface friction force of the string of the outer layer of the coating film 16 formed with polyamide. Under the same conditions, the chord gauge was set to 0.67mm, and the thickness of the outer layer of the coating film 16 was set to 10 μm. As a result, the results shown in table 1 were obtained. The terpene resin is a tackifying resin processed from turpentine and orange oil as raw materials.

[ Table 1]

The surface friction of the string using the polyamide added with terpene resin was 7.6N, which is greater than 6.3N of the surface friction of the string using polyamide, but less than 9N, which facilitates additional rotation. On the other hand, the surface friction force of the string using polyurethane and rubber was 12.5N and 21.4N, respectively, which was greater than 6.3N, and greater than 9N, which facilitates additional rotation. From this, it is known that sufficient frictional force can be obtained by using polyurethane or rubber as a coating agent.

Further, when the shuttlecock is additionally rotated by the string, it is preferable to use polyurethane or rubber as a material of the outer layer of the coating film 16. Further, from the viewpoint of processing stability, it is more preferable to use polyurethane. The material of the outer layer of the coating film is not limited to the above-mentioned material, and may be any material as long as the surface friction of the string is 9N or more. For example, even if polyamide or polyamide added with terpene resin is used, the thickness of the coating film 16 and the size of the string gauge are adjusted so that the surface friction of the string is 9N or more, and thus the coating film can be used as a material of the coating film. Further, if the surface friction of the string is 9N or more, the outer layer may be formed of the same material as the inner side of the coating film, for example, polyamide.

Next, the ball cutting performance is explained. Fig. 6 is a diagram showing a relationship between the horizontal line standard and the vertical line movement amount in the present embodiment. Fig. 7 is a diagram showing a relationship between the horizontal line standard and the frictional force when the vertical line moves in the present embodiment. Fig. 8 is a diagram showing a relationship between a frictional force on a lateral line and a frictional force when a vertical line moves in the present embodiment. In addition, the following are shown, respectively: in fig. 6, the horizontal axis represents the size of the horizontal line standard, and the vertical axis represents the amount of movement of the vertical line, in fig. 7, the horizontal axis represents the size of the horizontal line standard, and the vertical axis represents the frictional force when the vertical line moves, in fig. 8, the horizontal axis represents the frictional force of the horizontal line, and the vertical axis represents the frictional force when the vertical line moves. Hereinafter, the string for the vertical line is referred to as the vertical line, the string for the horizontal line is referred to as the horizontal line, the string specification for the vertical line is referred to as the vertical line specification, and the string specification for the horizontal line is referred to as the horizontal line specification, as appropriate.

As shown in FIG. 6, the ball cutting performance was confirmed by changing the cross-cut gauge of the vertical line having a thickness of 0.67mm and 10 μm of the polyurethane film. Here, a racket of ARC8DX (manufactured by Unix corporation) was struck with a vertical line and a horizontal line stretched at 25 pounds at a striking angle of 30 ° and a head speed of 200km/h using a pinball machine. When the transverse dimension is 0.65mm, the amount of longitudinal movement is about 5.50mm, and when the transverse dimension is 0.63mm, the amount of longitudinal movement is 6.00mm or more. Thus, the following was confirmed: the smaller the horizontal line gauge, the more the vertical line movement amount increases, and it becomes easy to additionally cut the shuttlecock.

Here, when the transverse line specification is changed and trial and error are repeated, the following is known: when the amount of the longitudinal movement is 6.0mm or more, the operator feels that additional cutting is easy. The friction force of the vertical line during movement was measured and was 2.2N or less. Therefore, the horizontal line specification and the horizontal line frictional force when the frictional force of the vertical line during movement became 2.2N or less were confirmed, and the results shown in fig. 7 and 8 were obtained. The friction force of the vertical line during movement is measured, for example, as follows: a cross thread was knitted on a vertical thread fixed with a load of 1000g, a load of 300g was attached to the cross thread, and the load cell was attached to a load cell FG-5005 (manufactured by zuo-tao-shi) and moved by an electric cylinder RCP2 (manufactured by IAI Corporation) as an electric slider.

Specifically, as shown in fig. 12, a 60 cm-long wire 82 is wound in a meandering manner around a plurality of roller pins 91a, one end of the wire 82 is fixed to a fixing pin 91b, and the other end of the wire 82 is attached to a weight 94 of 1000g via a pulley 92. Further, a transverse wire 81 of 90cm is wound around the plurality of roller pins 91c through the longitudinal wire 82, one end of the transverse wire 81 is attached to a hook 96 of a dynamometer 97, and the other end of the transverse wire 81 is attached to a weight 95 of 300g via a pulley 93. Thereby, the lateral lines 81 and the vertical lines 82 contact at a plurality of intersection positions 85 (15 positions in the present embodiment).

The force gauge 97 was attached to the electric slider 98 and slid at a drawing speed of 600mm/min and a moving distance of 100mm, and the slidability was measured. That is, the friction force when the vertical line moves is a relative friction force when the horizontal line 81 to which the 300g weight is attached is slid with respect to the vertical line 82 to which the 1000g weight is attached in a state of being in contact at a plurality of intersection positions 85 (15 positions in the present embodiment).

As shown in FIG. 7, the friction force when the vertical line was moved was confirmed by changing the horizontal line gauge with respect to the vertical line gauge of 0.67mm and the polyurethane film thickness of 10 μm. When the transverse wire gauge is 0.65mm, the friction force when the longitudinal wire moves is about 2.6N, and the longitudinal wire becomes difficult to move and the cutting becomes difficult to be applied. Further, when the transverse wire gauge is 0.63mm or less, the frictional force when the longitudinal wire moves becomes 2.2N or less, the longitudinal wire easily moves, and the cutting easily adds. Thus, the following was confirmed: the cutting performance is improved by the dimension of 0.67mm in the vertical line and the dimension of 0.63mm or less in the horizontal line, that is, the dimension of 94% or less in the vertical line.

As shown in fig. 8, the friction force when the vertical line moves was confirmed by changing the surface friction force of the horizontal line having a horizontal line gauge of 0.61mm with respect to the vertical line having a vertical line gauge of 0.67mm and a surface friction force of 4.3N. When the surface friction force of the lateral line is 2.3N, the friction force when the vertical line moves becomes about 2.8N, the vertical line becomes difficult to move, and the cutting becomes difficult to be applied. Further, when the friction force of the lateral line becomes 2.0N or less, the friction force becomes 2.2N or less when the vertical line moves, the vertical line easily moves, and the cutting becomes easy to be added. Thus, the following was confirmed: the surface friction force of the longitudinal line is 4.3N, and the surface friction force of the transverse line is less than 2.0N, so that the cutting performance is improved.

Next, the hitting feel and the edge breakage rate will be described. Fig. 9 is an explanatory diagram of the hitting feel and the edge breakage rate of the present embodiment. Fig. 9A is an explanatory view of the feel of hitting a ball, and fig. 9B is an explanatory view of the edge fracture rate.

As shown in fig. 9A, when the vertical and horizontal line sizes were the same and when the vertical and horizontal line sizes were large and the horizontal line size was small, the shuttlecock was struck and compared, and the feeling of striking was confirmed. When the vertical line specification and the horizontal line specification are both 0.67mm, the rebound feeling of the badminton is reduced. In addition, when the vertical line specification and the horizontal line specification are both 0.63mm, the rebound feeling of the shuttlecock is increased. Thus, when the vertical thread gauge is the same as the horizontal thread gauge, the rebound feeling is improved by reducing the vertical thread gauge together with the horizontal thread gauge.

On the other hand, when the vertical yarn gauge is 0.67mm and the horizontal yarn gauge is 0.61mm, the same rebound feeling as that when both the vertical yarn gauge and the horizontal yarn gauge are 0.63mm is obtained. That is, a more excellent rebound feeling was obtained when the gauge was 0.67mm in both the vertical and horizontal lines. Thus, the following was confirmed: even when the vertical yarn gauge is increased, a sufficient rebound feeling is obtained by decreasing the horizontal yarn gauge.

As shown in fig. 9B, the shuttlecock was hit and compared between the case where the vertical yarn size and the horizontal yarn size were the same and the case where the vertical yarn size was large and the horizontal yarn size was small, and the edge breakage rate was confirmed. Here, a test-play test was performed by stretching a vertical string and a horizontal string on a racket at 30 to 32 pounds. The edge cracking means that strings are cut at the edge of the racket, and the edge breakage rate is the probability of cutting the edge of a vertical string or a horizontal string stretched across the racket. The edge breakage rate was about 68% when the gauge of the longitudinal line and the gauge of the transverse line were both 0.63 mm.

In contrast, when the vertical line gauge is 0.67mm and the horizontal line gauge is 0.61mm, the edge breakage rate is reduced to about 32%. By increasing the specification of the longitudinal line and decreasing the specification of the transverse line, the edge fracture rate is greatly reduced. This is because the edge cutting is usually easily caused by the vertical line, and the size of the vertical line is more likely to affect the edge breakage rate than the size of the horizontal line. Thus, the following was confirmed: even when the lateral line gauge is reduced, the edge breakage rate can be reduced by increasing the vertical line gauge.

From the results of fig. 9A and 9B, the following was confirmed: by increasing the vertical line gauge and decreasing the horizontal line gauge, the edge breakage rate can be reduced without losing the hitting feeling of the shuttlecock. Therefore, the deficiency of the sense of bounce due to the increase in the vertical yarn gauge in order to improve the front light ball-picking performance can be compensated by reducing the horizontal yarn gauge. Further, the increase in the edge breakage rate caused by the reduction of the cross gauge for improving the ball cutting performance can be reduced by increasing the cross gauge.

Next, the ease of setting will be explained. In general, when a vertical string and a horizontal string are stretched over a racket, the vertical string is stretched over the racket, and then the horizontal string is stretched over the vertical string so as to pass through the vertical string. Therefore, in a state where the vertical strings are stretched on the racket, the stretching easiness varies depending on the passing easiness of the horizontal strings with respect to the vertical strings. Fig. 10 is a diagram showing a relationship between the horizontal line standard and the frictional force when the vertical line passes through the present embodiment. In fig. 10, the horizontal axis represents the size of the horizontal line standard, and the vertical axis represents the frictional force when passing through the horizontal line. If the friction force when passing the lateral line is 3.0N or more, the sliding is deteriorated, and the region is hard to stretch.

As shown in FIG. 10, the ease of passage of the transverse line with respect to the longitudinal line having a thickness of 10 μm of polyurethane was confirmed by using the transverse line coated with polyurethane (having a thickness of 10 μm) and the transverse line coated with nylon. When a polyurethane-coated cross thread is used, the cross thread gauge is in the range of 0.55 to 0.70mm, and the friction force when passing through the cross thread on a vertical thread becomes 3.0N or more, thereby deteriorating the sliding of the cross thread. Therefore, if the surface friction is increased by coating polyurethane on both the vertical and horizontal lines, the ease of stretching is reduced.

On the other hand, when the transverse threads coated with nylon are used, the transverse thread gauge is in the range of 0.55 to 0.70mm, and the frictional force when the transverse threads pass over the longitudinal threads is 3.0N or less, so that the transverse threads slide well. Therefore, the tensile easiness is improved by coating the normal nylon on the transverse wires to suppress the surface friction. Thus, the reduction in the ease of stretching caused by increasing the surface friction of the vertical threads to improve the front light ball-picking performance can be compensated by reducing the surface friction of the horizontal threads.

(examples)

The present invention will be described in more detail based on examples, but this is for illustrative purposes and the scope of the present invention is not limited to the examples described below.

A string having a string gauge of 0.67mm and a polyurethane film thickness of 0 μm, 4 μm, and 6 μm was prepared, and actual trial evaluation of the ball was performed. The evaluation was made by classifying the addition of spin into 6 ranks of "good addition", "slight addition", "normal", "slight addition not on", and "addition not on" by 10 middle and high-level players aged 20 to 50. As a result, the results shown in table 2 were obtained.

[ Table 2]

The thickness of the polyurethane film was evaluated as a standard (normal) film thickness. On the other hand, when the thickness of the polyurethane film was 4 μm, 9 persons rated "add" and only 1 person rated "add nothing". When the thickness of the polyurethane film was 6 μm, 4 persons rated "good addition", 3 persons rated "addition", 2 persons rated "slight addition", and only 1 person rated "slight addition". That is, the film thickness of the polyurethane was any of 4 μm and 6 μm chords, and 9 out of 10 persons evaluated as more additional rotation than "normal". Thus, the film thickness of the polyurethane was 4 μm and 6 μm, that is, the surface friction was 9N or more (see FIG. 5), and it was evaluated that the rotation was easily applied.

Next, transverse lines of 0.65mm, 0.63mm, 0.61mm and 0.58mm in transverse line gauge and longitudinal lines of 0.67mm in longitudinal line gauge and 10 μm in polyurethane film thickness were prepared and the actual test ball evaluation was performed. Here, the vertical and horizontal lines were set to 23 pounds on a NR900 (manufactured by yokex corporation), and the addition of a ball was rated in 5 ranks of "add", "slightly add", "normal", "slightly add", and "add" by 10 middle-high players aged 20 to 50. As a result, the results shown in table 3 were obtained.

[ Table 3]

When the size of the horizontal line gauge is 0.65mm, 2 persons rate "add", 2 persons rate "slightly add", 2 persons rate "normal", and 4 persons rate "slightly do not add". When the dimension of the horizontal line standard is 0.63mm, 2 persons are evaluated as "plus", 4 persons are evaluated as "slightly plus", 3 persons are evaluated as "normal", and 1 person is evaluated as "slightly not plus".

When the size of the horizontal line gauge is 0.61mm, 2 persons rate "add", 5 persons rate "slightly add", 2 persons rate "normal", and 1 person rate "slightly not add". When the size of the horizontal line gauge is 0.58mm, 7 persons rate "add" and 3 persons rate "slightly add". That is, the chord of 0.63mm, 0.61mm or 0.58mm in the dimension of the transverse line standard was evaluated to be higher than the "normal" value by more than half.

As described above, in the string group 20 of the present embodiment, the vertical string 21 having a larger diameter than the horizontal string 22 in surface friction is used, so that the frictional force between the shuttlecock and the vertical string 21 is increased and the contact area is increased. Therefore, it becomes easy to additionally rotate the rebounded shuttlecock when the shuttlecock is lightly picked in front of the net, thereby improving the performance of the light-picking shuttlecock in front of the net. Further, by using the small-diameter string 22 for lateral line having a smaller surface friction than the string 21 for longitudinal line, the friction between the string 21 for longitudinal line and the string 22 for lateral line is reduced, and the contact area is reduced. Therefore, the string 21 for the vertical line is easily moved relative to the string 22 for the horizontal line at the time of ball cutting, and the ball cutting performance is improved. In this way, the functions are assigned to the strings 21 for the longitudinal strings and the strings 22 for the transverse strings, and the light ball-picking performance at the net front, which is improved by increasing the surface friction force and the outer diameter of the strings, and the ball-cutting performance, which is improved by decreasing the surface friction force and the outer diameter of the strings, can be achieved at the same time.

The present invention is not limited to the above-described embodiments, and can be implemented by being variously modified. In the above-described embodiments, the size, shape, orientation, and the like shown in the drawings are not limited thereto, and can be appropriately changed within a range in which the effects of the present invention are exhibited. The present invention can be implemented with appropriate modifications without departing from the scope of the object of the present invention.

For example, in the present embodiment, the linear structure 13 is provided in a structure in which the

side wires

12a and 12b are woven around the core wire 11, but may be constituted by only the core wire 11. Further, the

side wires

12a and 12b are woven around the core wire 11, but may be wound only one layer around the core wire 11. Further, the lateral wires may be wound in two layers, and the first layer and the second layer may have different chord specifications (outer diameters).

In the present embodiment, the core wire 11 and the

side wires

12a and 12b may be formed of any one of a multifilament and a monofilament, and the number is not limited. When the core wire 11 is a single wire, the cross section is not limited to a circular cross section, and may be a polygon (e.g., a pentagon). Furthermore, hollow threads may be used for the core thread 11 and the

side threads

12a and 12 b.

In the present embodiment, the

strings

21 and 22 are provided in a structure formed of synthetic fibers, but are not limited thereto. The string-like structures 13 of the

strings

21 and 22 may be formed of natural strings made of natural fibers such as sheep intestines and whale tendons.

In the present embodiment, the structure in which the polyamide is coated on the lateral string cord 22 is described, but the structure is not limited to this. If the frictional force can be made smaller than that of the string 21 for longitudinal string, the string 21 for longitudinal string can be easily moved to improve the ball cutting performance, and the coating film of the string 22 for transverse string can be formed.

In the present embodiment, the string having a small diameter and a large diameter and having a large friction is used as the lateral line and the longitudinal line, respectively. The string with small diameter and small friction force is used as the longitudinal line, and the string with large diameter and large friction force is used as the transverse line, so that the light ball-picking energy and the ball-cutting performance in front of the net can be considered.

The present application is based on Japanese patent application 2016-. The contents of which are all incorporated herein.

Claims

1. A string group for a badminton racket, which is characterized in that,

the badminton racket is stretched as a longitudinal line and a transverse line,

the string set includes:

a small-diameter string for a lateral line having a small surface friction and stretched as the lateral line, an

A string for a longitudinal thread having a larger surface friction than the string for a lateral thread,

the friction force of the string for the longitudinal thread with respect to the shuttlecock becomes large and the contact area becomes large, so that the additional rotation to the rebounded shuttlecock during the previous light peach ball becomes easy, and

the friction force between the string for the lateral line and the string for the longitudinal line is reduced, the contact area is reduced, the string for the lateral line and the string for the longitudinal line are easy to move relatively during the ball cutting,

the outer diameter of the string for transverse wires is 94% or less of the outer diameter of the string for longitudinal wires,

coating films are formed on the strings for transverse lines and the strings for longitudinal lines,

the coating film of the string for a crosswire is formed of polyamide,

at least the outer layer of the coating film of the string for a longitudinal line is formed of polyurethane or rubber, and has a property that the gripping force becomes larger as the film thickness increases.

2. The string set for a badminton racquet according to claim 1,

the friction force during the movement of the string for the longitudinal string with respect to the string for the transverse string is 2.2N or less.

3. The string set for a badminton racquet according to claim 1,

the front surface friction of the racket formed by the strings for the transverse strings and the strings for the longitudinal strings is 9N or more.

4. A string for a cross string of a badminton racket is characterized in that,

strings for the longitudinal strings are crossed and stretched on the badminton racket,

the string for a vertical line has a smaller surface friction force and a smaller diameter than the string for a vertical line, and is easy to move relatively when a ball is cut, and has an outer diameter of 94% or less of the outer diameter of the string for a vertical line, and a coating film made of polyamide is formed.

5. A string for a longitudinal line of a badminton racket is characterized in that,

strings for cross and stretched on the cross string are arranged on the badminton racket,

compared with the string for the transverse wire, the string for the transverse wire has large surface friction and diameter, and larger friction and larger contact area relative to the shuttlecock, so that the additional rotation of the pre-peach ball on the rebounded shuttlecock becomes easy, a coating film is formed, at least the outer layer of the coating film is formed by polyurethane or rubber, and the coating film has the property that the holding power becomes larger along with the increase of the film thickness,

the outer diameter of the string for transverse wires is 94% or less of the outer diameter of the string for longitudinal wires.