KR102668581B1 - String sets, warp strings and weft strings - Google Patents

Abstract

To provide string sets that can improve hairpin performance and cut performance. The string set 20 is a string set woven with warp and weft for a racket, and is a first string set with a small diameter and a small friction force woven with either the warp or weft. It is characterized in that it is provided with a string 22 and a second string 21 that is woven with either warp or weft yarns and has a greater friction force and a larger diameter than the first string. For this reason, the functions were divided into the first string and the second string to achieve both hairpin performance, which is improved by the large surface friction and outer diameter of the string, and cut performance, which is improved by the small surface friction and outer diameter of the string.

Description

String sets, warp strings and weft strings

The present invention relates to string sets, warp strings and weft strings woven into a racket.

Generally, in a badminton racket, warp (warp) strings and weft (weft) strings are woven so that they intersect, and a face surface that catches a shuttlecock is formed. It is known that each string is made by rolling or braiding side yarns around a multifilament core yarn and coating the outer surface. For such strings, various proposals have been made to improve functions such as durability (for example, see Patent Document 1). For example, the durability of the string described in Patent Document 1 is improved by adding metal powder such as titanium to the coating agent.

Patent Document 1: Japanese Patent Laid-Open No. 3166031 (2001.03.09)

However, in badminton, shots called hairpins and shots called cuts are known. A hairpin is a shot in which a shuttlecock that has fallen in front of the net is lightly struck into the opponent's court, and a cut is a shot in which a shuttlecock that has flown over the head is intercepted (cut) diagonally with the face of the racket and dropped in front of the opponent's net. These shots require different string functions, and it has become difficult to improve hairpin performance (spin performance) and cut performance at the same time.

The present invention was made in consideration of the above points, and its purpose is to provide a string set, a warp string, and a weft string that can improve hairpin performance and cut performance.

The string set of the present invention is a string set woven with warp and weft for a racket, and is a string set with a small diameter and a small surface friction force woven with either warp or weft. It is characterized by comprising one string and a second string having a larger diameter and having a greater surface friction than the first string, which is woven with either warp or weft yarns.

Due to this configuration, the surface friction force of the second string is large and the diameter is large, so the friction force against the shuttlecock increases and the contact area increases. Therefore, the shuttlecock bounced during the hairpin is more likely to spin, thereby improving hairpin performance. Additionally, since the surface friction of the first string is small and has a small diameter, the friction between the first and second strings decreases and the contact area decreases. Accordingly, the first string and the second string become relatively easy to move during cutting, thereby improving cutting performance. In this way, by distributing the performance between the first string and the second string, hairpin performance improved by the large surface friction force and outer diameter (outer diameter) of the string and cut performance improved by the small surface friction force and outer diameter of the string are achieved. You can do it.

In the string set of the present invention, the first string is a weft string, and the second string is a warp string. According to this configuration, in addition to achieving both hairpin performance and cut performance, the lack of hitting feeling (bounce feeling) caused by an increase in the outer diameter of the warp string can be compensated for by reducing the outer diameter of the weft string. Additionally, by increasing the outer diameter of the warp string, which is prone to edge breakage, the probability of edge breakage can be reduced.

In the string set of the present invention, the frictional force when the second string moves with respect to the first string is 2.2 [N] or less. This configuration makes it easier for the second string to move relative to the first string, thereby improving cut performance.

In the string set of the present invention, the outer diameter of the first string is 94% or less of the outer diameter of the second string. Due to this configuration, even if the hairpin performance is improved by making the second string large in diameter, the cut performance can be improved by making it easier to move the second string with respect to the first string.

In the string set of the present invention, the surface friction force of the face surface of the racket formed by the first string and the second string is 9 [N] or more. Due to this configuration, the surface friction of the face surface increases, making it easy for a shuttlecock bounced off the face surface to spin.

In the string set of the present invention, a coating film is formed on the second string, and at least the surface layer of the coating film of the second string has the ability to increase the grip force as the film thickness increases. Due to this configuration, the grip force is increased by the film thickness of at least the surface layer of the coating film of the second string, and thus the surface friction force of the second string can be increased.

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

The weft string of the present invention is a weft string that is tied across a warp string to a racket, and is characterized by having a smaller surface friction force and a smaller diameter than that of the warp string.

Due to this configuration, the surface friction of the weft string is made smaller and the diameter is smaller than that of the warp string, so the friction between the strings becomes smaller and the contact area becomes smaller. Therefore, the warp string becomes easier to move relative to the weft string during cutting, thereby improving cutting performance. In addition, even if the hairpin performance is improved by making it easier to spin by using a warp string with a large surface friction force and a large diameter, the cut performance does not deteriorate because the warp string moves sufficiently with respect to the weft string. In this way, by distributing the functions between the warp string and the weft string, it is possible to achieve both hairpin performance, which is improved by the large surface friction and outer diameter of the string, and cut performance, which is improved by the small surface friction and outer diameter of the string.

The warp string of the present invention is a warp string that is tied across a weft string to a racket, and is characterized by having a larger surface friction force and a larger diameter than the weft string.

Due to this configuration, the surface friction of the warp string is increased and its diameter is made larger than that of the weft string, thereby increasing the friction between the shuttlecock and the warp string and increasing the contact area. Therefore, the shuttlecock bounced during the hairpin is more likely to spin, thereby improving hairpin performance. In addition, even if the cut performance is improved by making it easier to move the warp string by using a weft string with a small surface friction and a small diameter, the hairpin performance does not deteriorate because the surface friction of the warp string is sufficiently large. In this way, by distributing the functions to the warp string and the weft string, it is possible to achieve both hairpin performance, which is improved by the large surface friction and outer diameter of the string, and cut performance, which is improved by the small surface friction and outer diameter of the string.

According to the present invention, hairpin performance and cut performance can be improved by using a combination of a small-diameter first string with a small surface friction force and a large-diameter second string with a large surface friction force.

Figure 1 is a front view of a racket with woven strings.
Figure 2 is an explanatory diagram of hairpin performance and cut performance of a comparative example.
Figure 3 is an explanatory diagram of the hairpin performance and cut performance of the present embodiment.
Figure 4 is a cross-sectional schematic diagram of the string of this embodiment.
Figure 5 is a diagram showing the relationship between the film thickness and string gauge of the polyurethane of the present embodiment.
Fig. 6 is a diagram showing the relationship between the weft gauge and the warp movement amount according to the present embodiment.
Fig. 7 is a diagram showing the relationship between the weft gauge of this embodiment and the frictional force during warp movement.
Fig. 8 is a diagram showing the relationship between the friction force of the weft yarn and the friction force during warp movement in this embodiment.
Fig. 9 is an explanatory diagram of the shot feeling and edge damage probability of the present embodiment.
Figure 10 is a diagram showing the relationship between the weft gauge of this embodiment and the frictional force when the weft is sandwiched.
Fig. 11 is an explanatory diagram of the method for measuring surface friction force according to the present embodiment.
Fig. 12 is an explanatory diagram of the method of measuring friction force when the slope moves in this embodiment.

Hereinafter, the string set of this embodiment will be described with reference to the attached drawings. 1 is a front view of a racket with woven strings. Figure 2 is an explanatory diagram of the hairpin performance and cut performance of a comparative example. Figure 3 is an explanatory diagram of the hairpin performance and cut performance of this embodiment. Additionally, the comparative example uses the same string for the warp and weft threads, while the present embodiment uses different strings for the warp and weft threads.

As shown in Figure 1, the frame 53 of the badminton racket 50 is woven so that the warp string 21 and the weft string 22 intersect, forming a face surface 54 for hitting the shuttlecock. It is done. The warp string 21 and the weft string 22 intersect at the intersection position so that the strings are turned upside down, and the warp string 21 and the weft string 22 are in contact only at this intersection position. When the shuttlecock touches the face surface 54, the impact is distributed to the warp string 22 and the weft string 21 through the intersection position, and the shuttlecock is bounced by the repulsive force of each string 21 and 22.

Known shots in badminton include shots called hairpins and shots called cuts. A hairpin is a shot in which the shuttlecock is lightly bounced with the face surface 54 of the racket 50 and returned to the front of the net of the opponent's court. In this case, the shuttlecock is struck with the face surface 54 of the racket 50 roughly horizontal, and when the shuttlecock is struck in a grazing manner, the bounced shuttlecock is spun and returned to the opponent's court in a trajectory close to the immediate top. A cut is a shot in which the shuttlecock is hit at an angle with the face (54) and dropped in front of the net of the opponent's court. In this case, the face surface 54 is set at an angle with respect to the shuttlecock, the inclined string 21 is moved by the shuttlecock, and when returning, the shuttlecock is rotated, drawing a sharply falling trajectory and returning to the opponent's court.

However, as in the comparative example shown in FIG. 2A, the same strings 41 and 42 are generally used for the warp and weft threads of the racket. In this case, the degree of spin when hitting the hairpin is important as a factor that determines hairpin performance. Spin is governed by the friction between the surfaces of the strings 41 and 42 and the cork leather of the shuttlecock. For this reason, in order to improve hairpin performance, it is important to increase the string gauge (outer diameter) and surface friction of the strings 41 and 42. Accordingly, if the string gauge and surface friction force of the strings 41 and 42 are increased to improve hairpin performance, it becomes difficult for the warp string 41 to move and the cut performance deteriorates.

On the other hand, as shown in FIG. 2B, it is important that the warp string 41 is easy to move as a factor determining cut performance. The degree of movability of the warp string 41 is influenced by the friction force or contact area between the strings. For this reason, in order to improve cut performance, it is important to reduce the string gauge and surface friction of the strings 41 and 42. Therefore, if the string gauge and surface friction of the strings 41 and 42 are reduced in order to improve the cut performance, it becomes difficult to spin the shuttlecock, thereby deteriorating the hairpin performance.

In this way, if the string gauge and friction force of the strings 41 and 42 are increased, hairpin performance improves, but cut performance deteriorates. Additionally, if the string gauge and surface friction of the strings 41 and 42 are reduced, the cut performance improves but the hairpin performance deteriorates. Since hairpin performance and cut performance are in a trade-off relationship, it was difficult to simultaneously improve hairpin performance and cut performance when the same strings 41 and 42 were used for the warp and weft yarns. In addition, if the string gauge is large, the feel at impact deteriorates, and if the string gauge is small, the edge becomes more likely to be damaged, and if the surface friction is large, it becomes difficult to tie.

Therefore, in this embodiment, the warp string 21 (second string), which has a large surface friction force and a large diameter, and the weft string 22 (first string), which has a small surface friction force and a small diameter, have hairpin performance and cut performance. The functions are distributed. In addition, the disadvantages arising from the increase in the string gauge and surface friction of the warp string 21 are attempted to be improved by reducing the string gauge and surface friction of the weft string 22. Conversely, the disadvantages caused by the small string gauge and surface friction of the weft string 22 are attempted to be improved by increasing the string gauge and surface friction of the warp string 21.

Specifically, as shown in FIG. 3A, the string set 20 of the present embodiment includes a warp string 21 with a larger diameter and a larger surface friction force than the weft string 22, and a warp string 21. It is composed of a weft string 22 with a smaller surface friction force and a smaller diameter. Since the warp string 21 has a large surface friction force and is formed with a large diameter, the friction force and contact area between the surface of the warp string 21 and the shuttlecock increase, making it easy for the shuttlecock to spin. In this way, by using the string 21 with a large surface friction force and a large diameter for the warp yarn, hairpin performance can be improved even if the string 22 with a small surface friction force and a small diameter is used for the weft yarn.

On the other hand, as shown in FIG. 3B, since the weft string 22 has a small surface friction force and is formed in a small diameter, the contact area and surface friction force between the strings 21 and 22 become small, and the weft string 22 ), the inclined string 21 becomes easier to move. The warp string 21 is greatly moved by the shuttlecock, and the force returning the warp string 21 to its original state acts on the shuttlecock, making it easier to apply a cut. In this way, by using the string 22 having a small surface friction and a small diameter for the weft, cut performance can be improved even if the string 22 having a large surface friction and a large diameter is used for the warp yarn.

Additionally, the lack of hitting feeling (bounce feeling) caused by an increase in the string gauge of the warp string 21 is compensated for by reducing the string gauge of the weft string 22. On the other hand, the degree to which edge damage occurs due to a small string gauge of the weft string 22 is compensated for by increasing the string gauge of the warp string 21, which is particularly prone to edge damage. In addition, the difficulty in tying caused by the increased surface friction of the warp string 21 is compensated for by reducing the surface friction of the weft string 22.

Hereinafter, the string set of this embodiment will be described in detail. Figure 4 is a cross-sectional schematic diagram of the string of this embodiment. Additionally, the cross-sectional structure of the string of this embodiment is not limited to the structure shown in FIG. 4 and can be changed as appropriate.

As shown in FIG. 4, the string 21 is constructed by forming a coating film 16 around a thread-shaped structure 13 consisting of a core seal 11 and side seals 12a and 12b. The thread-like structure 13 is constructed by braiding side threads 12a and 12b around a multifilament core thread 11. The side yarns 12a and 12b are made up of a plurality of side yarns, and 8 sets in the S direction and 8 sets in the Z direction are braided to surround the core yarn 11.

Around the thread-like structure 13, polyamide or the like is coated on the inside, and then polyurethane is coated on the surface to form a coating film 16 with a predetermined film thickness. That is, the coating film 16 is composed of a two-layer structure of an inner coating layer (inner layer) and an outer coating layer (surface layer), and the friction force (coefficient of friction) of the outer coating layer is higher than that of the inner coating layer. Additionally, the coating film 16 may be formed solely of polyurethane. In addition, in the following description, the film thickness (t) of the coating film 16 of the warp string 21 represents the thickness from the outermost surface of the thread-shaped structure 13.

In addition, although not shown in detail, the weft string 22 is formed in approximately the same way as the warp string 21, except that the coating film is formed only of polyamide and the outer diameter of the thread-like structure is small. . Unlike the warp string 21, the weft string 22 has a surface friction force smaller than that of the warp string 21 because the surface layer of the coating film is also formed of polyamide. In addition, the materials of the core yarn and side yarn of the warp string 21 and the weft string 22 are not particularly limited, but for example, polyamide, polyester, etc. are used.

Next, hairpin performance will be described. Figure 5 is a diagram showing the relationship between the film thickness and string gauge of the polyurethane of the present embodiment. Additionally, in Figure 5, the horizontal axis represents the polyurethane film thickness of the surface layer of the coating film, and the vertical axis represents the string gauge. Additionally, the coating film is formed of polyurethane and polyamide as described above, and by reducing the film thickness of the polyamide on the inside, it becomes possible to increase the film thickness of the polyurethane on the surface layer. Additionally, the gauge indicates the outer diameter when towing 25 ponds.

As shown in Figure 5, as a result of repeatedly hitting the hairpin while changing the surface friction of the string, the player is prone to spin on the shuttlecock when the surface friction of the string is 9 [N] or more, and is prone to spin on the shuttlecock when the surface friction of the string is 12 [N] or more. It was found that it felt more prone to spin. Therefore, as a result of investigating the relationship between the film thickness of the coating film and the string gauge where the surface friction of the string is 9 [N] or more and 12 [N] or more, results as shown in the drawing were obtained. Here, a string surface friction force of 9 [N] or more is described as a spin region, and a string surface friction force of 12 [N] or more is described as a high spin region.

When the polyurethane film thickness shown on the horizontal axis of Figure 5 is 0 [㎛], the string gauge is in the range of about 0.80 [mm] -0.94 [mm], R1 becomes the spin region, and the string gauge is about 0.94 [mm] or more. Range R2 becomes the high spin region. Also, when the polyurethane film thickness is 8 [㎛], R3 in the range of about 0.50 [㎜] -0.65 [㎜] with the string gauge becomes the spin region, and R4 in the range of about 0.65 [㎜] or more with the string gauge is high. It becomes a spin area. In other words, as the polyurethane film thickness increases, the area prone to spin expands, making it possible to obtain a surface friction force of 9 [N] or more even if the string gauge is small. Additionally, the gauge indicates the outer diameter when towing 25 ponds.

When the string gauge shown on the vertical axis in FIG. 5 is 0.50 [mm], the range R5 where the film thickness is 8 [μm] or more becomes the spin region. Additionally, when the string gauge is 0.80 [㎜], the range R6 where the polyurethane film thickness is 0 [㎛] -2 [㎛] becomes the spin region, and the range R7 where the polyurethane film thickness is 2 [㎛] or more is the spin region. It becomes a high spin area. In other words, as the string gauge increases, the area prone to spin expands, making it possible to obtain a friction force of 9 [N] or more even if the polyurethane film thickness is small. In this way, the larger the polyurethane film thickness and string gauge, the wider the area prone to spin. In addition, the surface friction force of the face surface 54 of the racket 50 formed by the weft string 22 and the warp string 21 is influenced by the surface friction force of the string (second string) with the larger surface friction force. easy to receive

When the polyurethane film thickness is large, the grip force for the shuttlecock increases, thereby increasing the surface friction of the string. Additionally, when the string gauge is large, the contact area between the surface of the string and the cork leather of the shuttlecock increases, thereby increasing the surface friction of the string. In this way, in this embodiment, an appropriate frictional force is provided to the surface of the string by adjusting the polyurethane film thickness and the string gauge. In addition, the friction force of the string described above is measured, for example, by sliding a weight with cork leather on the contact surface over the string surface hung on the racket using Autograph AG-IS (produced by Shimadzu Corporation). .

Specifically, as shown in FIG. 11, a racket 50 with strings 21 and 22 strung vertically and horizontally is placed on a horizontal table 60, and a plate shape to which cork leather 31 is attached is attached. The weight 32 (1 [kg]) is raised. One end of a wire 33 is attached to the weight 32, and the other end of the wire 33 is connected to the chuck 72 of the tensile tester 70 (Autograph AG-IS) through the sheave 71. It is installed. Due to the rise of the chuck 72, the weight 32 on the surface of the string 21 is tensioned, and the frictional force generated between the strings 21 and 22 and the cork leather 31 is measured as the tensile force of the tensile tester 70. . That is, the surface friction force of the string 21 is the friction force when a weight 32 with a weight of 1 [kg] and attached with a cork leather 31 is slid against the strings 21 and 22.

Next, in order to select the optimal material, the surface friction of the string was measured by forming the surface layer of the coating film with three types of polyamide with terpene resin, polyurethane with excellent production stability, and rubber with excellent friction properties, and using polyamide. The surface friction force of the string forming the surface layer of the coating film 16 was compared. Additionally, as common conditions, the string gauge was set to 0.67 [mm] and the film thickness of the surface layer of the coating film 16 was set to 10 [μm]. As a result, the results shown in Table 1 were obtained. Terpene resin is a tackifying resin processed from terpene oil or orange oil.

Surface layer of coating film surface friction polyamide standard
(6.3N) Polyamide + Terpene Resin △
(7.6N) Polyurethane ○
(12.5N) rubber ○
(21.4N)

The surface friction force of the string using polyamide with added terpene resin was 7.6 [N], which was greater than the surface friction force of 6.3 [N] for the string using polyamide, but less than 9 [N], which is prone to spin. In contrast, the surface friction of strings made of polyurethane and rubber are 12.5 [N] and 21.4 [N], respectively, which is greater than the surface friction of 6.3 [N] of strings made of polyamide, which makes it more prone to spin. N] It was more than that. As a result, it was found that sufficient frictional force could be obtained by using polyurethane or rubber as a coating agent.

Therefore, when spinning a shuttlecock with a string, it is preferable that polyurethane or rubber be used as the material for the surface layer of the coating film 16. Additionally, from the viewpoint of processing stability, it is more preferable to use polyurethane. Additionally, the material for the surface layer of the coating film is not limited to the above-mentioned materials, and may be any material that provides a string surface friction force of 9 [N] or more. For example, even if it is polyamide or polyamide to which terpene resin has been added, it can be used as a coating film material by adjusting the film thickness of the coating film 16 and the size of the string gauge to set the surface friction of the string to 9 [N] or more. You can. Additionally, if the surface friction of the string is 9 [N] or more, the surface layer may be formed with the same material as the inside of the coating film, for example, polyamide.

Next, cut performance will be explained. Fig. 6 is a diagram showing the relationship between the weft gauge and the warp movement amount in this embodiment. Fig. 7 is a diagram showing the relationship between the weft gauge of this embodiment and the frictional force during warp movement. Figure 8 is a diagram showing the relationship between the frictional force of the weft yarn and the frictional force during warp movement in this embodiment. In addition, in Figure 6, the horizontal axis is the size of the weft gauge, the vertical axis is the movement amount of the warp yarn, in Figure 7, the horizontal axis is the size of the weft yarn gauge, the vertical axis is the friction force when the warp yarn moves, and in Figure 8, the horizontal axis is the friction force of the weft yarn, and the vertical axis is represents the friction force when the slope moves. In the following, the warp strings are appropriately referred to as warp yarns, the weft strings are referred to as weft yarns, the string gauges for warp yarns are called warp gauges, and the string gauges for weft yarns are referred to as weft gauges.

As shown in Figure 6, the cut performance was confirmed by changing the weft gauge for a warp yarn with a warp gauge of 0.67 [mm] and a polyurethane film thickness of 10 [μm]. Here, the warp and weft threads were tied to an ARC8DX (Yonex Co., Ltd. product) racket with a 25 pond, and a smash machine was used at a hitting angle of 30° and a swing speed of 200 [km/h]. When the weft gauge is 0.65 [mm], the warp movement amount is about 5.50 [mm], and when the weft gauge is 0.63 [mm], the warp movement amount is 6.00 [mm] or more. As a result, it was confirmed that as the weft gauge becomes smaller, the amount of warp movement increases, making it easier to apply a cut to the shuttlecock.

Here, as a result of repeated trials while changing the weft gauge, it can be seen that the player feels that the cut can be easily applied when the warp movement amount is 6.0 [mm] or more. The friction force when the slope moved at this time was measured and was 2.2 [N] or less. Therefore, as a result of checking the friction force of the weft gauge and the weft yarn, where the friction force when the warp yarn moves is 2.2 [N] or less, the results shown in Figures 7 and 8 were obtained. In addition, the friction force when the warp yarn moves can be measured, for example, by applying a load of 1000 g, inserting the weft yarn into the fixed warp yarn, applying a load of 300 g to the weft yarn, installing it on a force gauge FG-5005 (made by Sato Corporation), and using an electric gauge. It is measured by moving the force gauge with the Robosilinder RCP2 (IAI Corporation product) as a slider.

Specifically, as shown in FIG. 12, a warp 82 of 60 [cm] is wound in a meandering manner on a plurality of roller pins 91a, and one end of the warp 82 is fixed to a fixing pin 91a. The other end of the warp 82 is installed on the weight 94 of 1000 [g] through the pulley 92. In addition, a 90 [cm] weft thread 81 is rolled around a plurality of roller pins 91c as if threading the warp thread 82, and one end of the weft thread 81 is connected to the hook 96 of the force gauge 97. It is installed, and the other end of the weft 81 is installed on the weight 95 of 300 [g] through the pulley 93. For this reason, the weft 81 and the warp yarn 82 are in contact at a plurality of intersection portions 85 (15 locations in this embodiment).

In addition, the force gauge 97 is installed on the electric slider 98, and the activity is measured by sliding it at a tensile speed of 600 [mm/min] and a moving distance of 100 [mm]. In other words, the friction force when the warp yarn moves means that the additional weft yarn 81 of 300 [g] is placed at a plurality of intersection parts 85 (15 places in this embodiment) with respect to the warp yarn 82 of 1000 [g] additionally installed. ) This is the relative friction force when sliding in a contact state.

As shown in FIG. 7, for a warp yarn with a warp gauge of 0.67 [mm] and a polyurethane film thickness of 10 [μm], the weft gauge was changed and the friction force when the warp yarn moved was confirmed. When the weft gauge is 0.65 [mm], the friction force when the warp yarn moves is about 2.6 [N], making it difficult for the warp yarn to move and making it difficult to apply a cut. Additionally, when the weft gauge is 0.63 [mm] or less, the friction force when the warp yarn moves becomes 2.2 [N] or less, making it easier for the warp yarn to move and for cuts to be applied. In this way, it was confirmed that cut performance improves when the weft gauge is 0.63 [mm] or less compared to the warp gauge of 0.67 [mm], that is, when the weft gauge is 94% or less of the warp gauge.

As shown in Figure 8, for a warp with a warp gauge of 0.67 [mm] and a surface friction of 4.3 [N], the surface friction of the weft with a weft gauge of 0.61 [mm] was changed to check the friction when the warp moved. . When the surface friction of the weft is 2.3 [N], the friction when the warp yarn moves becomes about 2.8 [N], making it difficult for the warp yarn to move and making it difficult to apply a cut. Additionally, when the friction force of the weft becomes 2.0 [N] or less, the friction force when the warp yarn moves becomes 2.2 [N] or less, making it easier for the warp yarn to move and making it easier to apply a cut. In this way, it was confirmed that cut performance was improved when the surface friction of the weft yarn was 2.0 or less compared to the surface friction of the warp yarn of 4.3 [N].

Next, the feel of the shot and the probability of edge damage are explained. Fig. 9 is an explanatory diagram of the shot feeling and edge damage probability of the present embodiment. FIG. 9A is an explanatory diagram of the feel of a shot, and FIG. 9B is an explanatory diagram of the probability of edge damage.

As shown in FIG. 9A, the shot feeling was checked by hitting a shuttlecock and comparing the case where the warp gauge and the weft gauge were the same and the case where the warp gauge was made large and the weft gauge was made small. When both the warp gauge and weft gauge were 0.67 [mm], the bouncing feeling of the shuttlecock was reduced. Additionally, when both the warp gauge and weft gauge were 0.63 [mm], the bouncing sensation of the shuttlecock increased. In this way, when the warp gauge and the weft gauge are the same, the bouncing feeling is improved by making both the warp gauge and the weft gauge smaller.

On the other hand, when the warp gauge was 0.67 [mm] and the weft gauge was 0.61 [mm], the same bouncing feeling was obtained as when both the warp gauge and the weft gauge were 0.63 [mm]. In other words, a better bouncing feeling was obtained than when both the warp gauge and weft gauge were set to 0.67 [mm]. In this way, it was confirmed that even when the warp gauge is large, a sufficient bounce feeling can be obtained by making the weft gauge small.

As shown in FIG. 9B, the hitting feel was confirmed by hitting a shuttlecock in a case where the warp gauge and the weft gauge were the same and a case where the warp gauge was made large and the weft gauge was made small. Here, a try-out test was conducted by tying warp and weft threads to a racket with 30 to 32 ponds. Additionally, edge damage means that the string is cut at the edge of the frame, and edge damage probability is the probability that the warp or weft threads tied to the racket will be edge damaged. When both the warp gauge and weft gauge were 0.67 [mm], the probability of edge damage was about 68%.

In contrast, when the warp gauge was 0.67 [mm] and the weft gauge was 0.61 [mm], the probability of edge damage decreased to about 32%. By increasing the warp gauge and reducing the weft gauge, the probability of edge damage is greatly reduced. This is believed to be because, in general, edge damage is likely to occur in the warp, and the size of the warp gauge is more likely to have an effect on the probability of edge damage than the size of the weft gauge. In this way, it was confirmed that even when the weft gauge is small, the probability of edge damage can be reduced by increasing the warp gauge.

From the results of FIGS. 9A and 9B, it was confirmed that it was possible to reduce the probability of edge damage without reducing the feeling of hitting the shuttlecock by increasing the warp gauge and reducing the weft gauge. Therefore, in order to improve hairpin performance, it is possible to compensate for the lack of bouncing feeling caused by increasing the warp gauge by making the weft gauge smaller. Additionally, in order to improve cut performance, it is possible to reduce the increase in the probability of edge damage caused by reducing the weft gauge by increasing the warp gauge.

Next, we will explain how easy it is to tie. Normally, when tying the warp and weft threads to a racket, the warp thread is tied to the racket and then the warp thread is inserted as if threading the weft thread. For this reason, the ease of tying changes depending on the ease of inserting the weft into the warp while the warp is tied to the racket. Fig. 10 is a diagram showing the relationship between the friction force when sandwiching the weft gauge and the weft of this embodiment. Additionally, in Figure 10, the horizontal axis represents the size of the weft gauge, and the vertical axis represents the friction force when inserting the weft thread. If the friction force when inserting the weft is more than 3.0N, it will not be smooth and the area will be difficult to tie.

As shown in Figure 10, in the case of using weft yarns coated with polyurethane (film thickness 10 [μm]) and the case of using weft yarns coated with nylon, the warp gauge is 0.67 [mm] and the film thickness of polyurethane is 10. The ease of inserting the weft for a warp of [㎛] was confirmed. When polyurethane-coated weft yarns are used, the friction force when inserting the weft yarns into the warp yarn when the weft gauge is in the range of 0.55-0.70 [mm] becomes 3.0 [N] or more, making the weft yarns not smooth. Therefore, if the surface friction is increased by coating both the warp and weft threads with polyurethane, the ease of tying decreases.

On the other hand, when a weft coated with nylon is used, the friction force when inserting the weft yarn into the warp yarn is 3.0 [N] or less when the weft gauge is in the range of 0.55-0.70 [mm], so the smoothness of the weft yarn is good. Therefore, the ease of tying is improved by coating the weft with conventional nylon to suppress surface friction. In this way, in order to improve hairpin performance, it is possible to compensate for the decrease in ease of tying caused by increasing the surface friction of the warp yarn by reducing the surface friction of the weft yarn.

(Example)

Hereinafter, the present invention will be described in more detail based on examples, but these are described for illustration purposes and the scope of the present invention is not limited to the following examples.

Strings with a string gauge of 0.67 [mm] and polyurethane film thicknesses of 0 [μm], 4 [μm], and 6 [μm] were prepared, and a trial evaluation of the hairpin was performed. Ten intermediate-to-advanced people in their 20s to 50s evaluated the degree to which the spin took place, divided into six levels: 'takes well', 'takes a bit', 'takes a little', 'average', 'slightly does not take', and 'does not take'. As a result, the results shown in Table 2 were obtained.

Polyurethane
Film thickness
［㎛］ How much spin it takes well
It takes It takes a little
It takes commonly a little
It doesn't catch It doesn't work
does not 0 0 0 0 10 0 0 4 0 9 0 0 0 One 6 4 3 2 0 One 0

The polyurethane film thickness of 0 [μm] was evaluated as a standard (normal). In contrast, when the film thickness of polyurethane was 4 [㎛], 9 people evaluated it as 'caught' and only 1 person evaluated it as 'not stuck'. In addition, when the polyurethane film thickness is 6 [㎛], 4 people evaluated it as 'it sticks well', 3 people evaluated it as 'it sticks', 2 people evaluated it as 'it takes a little bit', and only 1 person evaluated it as 'slightly not sticking'. In other words, for either string with a polyurethane film thickness of 4 [μm] or 6 [μm], 9 out of 10 people evaluated that it spins more than 'normally'. In this way, it was evaluated that spin is likely to occur when the polyurethane film thickness is 4 [μm] or 6 [μm], that is, when the surface friction force is 9 [N] or more (see FIG. 5).

Next, prepare a warp yarn with a weft gauge of 0.65 [mm], 0.63 [mm], 0.61 [mm], and 0.58 [mm], a warp gauge of 0.67 [mm], and a polyurethane film thickness of 10 [㎛]. So, a trial evaluation of the cut was conducted. Here, the warp and weft threads were tied with a 23 pond thread on an NR900 racket (manufactured by Yonex Co., Ltd.), and 10 middle-to-upper-level players in their 20s to 50s were asked to rate the degree of cut as 'takes', 'takes a little', 'normal', and 'takes a little'. The evaluation was divided into five levels: ‘does not take’ and ‘does not take’. As a result, the results shown in Table 3 were obtained.

weft
Gauge [㎜] It takes a little
It takes commonly a little
It doesn't catch It doesn't catch 0.65 2 2 2 4 0 0.63 2 4 3 One 0 0.61 2 5 2 One 0 0.58 7 3 0 0 0

When the size of the weft gauge is 0.65 [mm], 2 people rated it as 'it takes', 2 people evaluated it as 'it takes a little bit', 2 people evaluated it as 'average', and 4 people evaluated it as 'slightly does not take it'. When the size of the weft gauge is 0.63 [mm], 2 people evaluated it as 'it takes', 4 people evaluated it as 'it takes a little bit', 3 people evaluated it as 'average', and 1 person evaluated it as 'it does not take a bit'. When the size of the weft gauge is 0.61 [mm], 2 people evaluated it as 'taking', 5 people evaluated it as 'slightly taking', 2 people evaluated it as 'average', and 1 person evaluated it as 'slightly not taking'. When the size of the weft gauge is 0.58 [mm], 7 people rated it as ‘taking’ and 3 people said ‘it takes a bit’. In other words, more than half of the strings with weft gauge sizes of 0.63 [mm], 0.61 [mm], and 0.58 [mm] were rated higher than 'normal'.

As described above, in the string set 20 of the present embodiment, by using the warp string 21, which has a larger surface friction force and a larger diameter than the weft string 22, the friction between the shuttlecock and the warp string 21 increases. At the same time, the contact area increases. Therefore, the shuttlecock bounced during the hairpin is more likely to spin, thereby improving hairpin performance. In addition, by using the weft string 22, which has a smaller surface friction force and a smaller diameter than the warp string 21, the friction between the warp string 21 and the weft string 22 decreases, and at the same time, the contact area decreases. Therefore, the warp string 21 becomes easier to move relative to the weft string 22 during cutting, thereby improving cutting performance. In this way, the performance is distributed between the warp string 21 and the weft string 22, so that the hairpin performance is improved by the large surface friction and outer diameter of the string, and the cut performance is improved by the small surface friction and outer diameter of the string. can be compatible.

Additionally, the present invention is not limited to the above embodiments and can be implemented with various modifications. In the above embodiment, the size, shape, direction, etc. shown in the accompanying drawings are not limited thereto and can be appropriately changed within the range of achieving the effect of the present invention. In addition, it is possible to implement the present invention with appropriate changes as long as it does not deviate from the scope of the purpose of the present invention.

For example, in this embodiment, the thread-like structure 13 has a structure in which the side threads 12a and 12b are braided around the core thread 11, but it may be composed of only the core thread 11. Also, although the side yarns 12a and 12b are braided around the core yarn 11, the side yarns may be braided only one layer around the core yarn 11. Additionally, the side seals may be rolled in two layers, and the string gauges (outer diameters) of the side seals of the first and second layers may be different.

Additionally, in this embodiment, the core yarn 11 and the side yarns 12a and 12b may be made of either multifilament or monofilament, and their number is not limited. Additionally, when the core thread 11 is a monofilament, the cross-section is not limited to a circular shape, and the cross-section may be polygonal (for example, pentagonal). Additionally, hollow threads may be used for the core seal 11 and the side seals 12a and 12b.

In addition, in this embodiment, the strings 21 and 22 are made of synthetic fibers, but the structure is not limited to this. The thread-like structures 13 of the strings 21 and 22 may be formed of natural strings made of natural fibers such as sheep stomach or whale tendon.

In addition, in this embodiment, a configuration in which polyamide is coated on the weft string 22 has been described, but the configuration is not limited to this configuration. The coating film of the weft string 22 may be formed in any way as long as the friction force is smaller than that of the warp string 21 and the cutting performance can be improved by making the warp string 21 easy to move.

In addition, in the present embodiment, a configuration in which a string with small friction and a small diameter is used in the weft yarn, and a string with a high friction force and a large diameter in the warp yarn is used, but the configuration is not limited to this. It is possible to achieve both hairpin performance and cut performance even when using a small diameter string with small friction in the warp yarn and using a large diameter string with high friction in the weft yarn.

This application is based on Japanese Patent Application No. 2016-089286, filed on April 27, 2016. All of this information is included here.

Claims (10)

In a set of strings woven with warp and weft yarns for a racket,
A first string woven with either warp or weft yarns;
and a second string having a larger diameter than the first string, which is woven with either warp or weft yarns,
The surface friction force of the second string, which is measured when a weight of 1 [kg] with cork leather attached is slid while placed horizontally and tied to a racket, is measured under the same conditions as the surface friction force of the second string. greater than the surface friction force of the first string,
The first string is a weft string,
A string set, characterized in that the second string is a warp string. According to paragraph 1,
A string set, characterized in that, on the face of the racket formed by the first string and the second string, the surface friction force measured under the same conditions as the surface friction force of the second string is 9 [N] or more. According to paragraph 2,
A coating film is formed on the second string,
A string set, wherein at least the surface layer of the coating film of the second string has the property of increasing grip strength as the film thickness increases. In a set of strings woven with warp and weft yarns for a racket,
A first string woven with either warp or weft yarns;
and a second string having a larger diameter than the first string, which is woven with either warp or weft yarns,
The surface friction force of the second string, which is measured when a weight of 1 [kg] with cork leather attached is slid while placed horizontally and tied to a racket, is measured under the same conditions as the surface friction force of the second string. greater than the surface friction force of the first string,
On the face of the racket formed by the first string and the second string, the surface friction force measured under the same conditions as the surface friction force of the second string is 9 [N] or more,
A coating film is formed on the second string,
A string set, wherein at least the surface layer of the coating film of the second string has the property of increasing grip strength as the film thickness increases. According to paragraph 4,
The first string is a weft string,
A string set, characterized in that the second string is a warp string. According to any one of claims 3 to 5,
A string set, wherein at least the surface layer of the coating film of the second string is formed of polyurethane or rubber. According to any one of claims 1 to 5,
When the second string moves with respect to the first string, the first string with a 300 [g] weight is in contact with the second string with a 1000 [g] weight at 15 intersection points. A string set characterized in that the frictional force measured when sliding is 2.2 [N] or less. According to any one of claims 1 to 5,
A string set, characterized in that the outer diameter of the first string is 94% or less of the outer diameter of the second string. In the weft string that is tied across the warp string to the racket,
The surface friction force measured when a weight weighing 1 [kg] with cork leather attached is slid while tied to a racket and placed horizontally is smaller than that of the warp string, and has a smaller diameter than the warp string. A weft string made of . In the warp string that is tied across the weft string to the racket,
The surface friction force measured when a weight of 1 [kg] with cork leather attached is slid while tied to a racket and placed horizontally is larger than that of the weft string, and has a larger diameter than the weft string. A warp string made of .

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