TWI706801B - Net cable for racket - Google Patents

Abstract

The net string for a racket of the present invention can obtain the advantages of forming a hollow portion and improve durability. The racket net wire (10) is provided with a core wire (11) and a plurality of side wires (12) wound around the outer side of the core wire. The core line includes a solid part (20) formed in a predetermined area including the central axis position (C), and a plurality of hollow parts (21) formed around the solid part and extending in the extending direction of the core line. The number of hollow parts formed is an odd number, and they are arranged at equal angles around the solid part.

Description

Net cable for racket

The present invention relates to a racquet wire used for tennis, badminton, squash, etc., and particularly to a racquet wire in which a plurality of side wires are wound around the outer side of a core wire.

In tennis or badminton rackets, stretch the net line on the surface of the racket in a mesh shape. In addition, a net wire in which a monofilament of a thin side wire is wound on the outside of a monofilament or a multifilament used as a core wire is widely used as a net for a racket. The above network cable is generally called "monofilament type" when the core wire is monofilament, and "multifilament type" when the core wire is multifilament.

As disclosed in Patent Document 1, the monofilament type mesh wire proposes a structure in which a hollow portion is formed at the center axis position of the core wire. The formation of the relevant hollow part can improve the elasticity of the net line and improve the vibration absorption performance when hitting the ball.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2005-237877

However, in the mesh wire of Patent Document 1, when a force is applied in the radial direction of the cross section, there is a problem that the hollow portion becomes easily crushed in the radial direction. This hollow part is likely to be crushed at the intersection of the vertical and horizontal lines of the net line, and is also likely to occur when hitting the ball. Therefore, there are problems such as reducing the durability of the net line due to the crushing.

The present invention has been developed in view of the above circumstances, and aims to provide a racket wire that can obtain the advantages of forming a hollow portion and improve durability.

The racket netting line of the present invention is set in a racket netting line extending in a predetermined direction, and includes a solid part formed in a predetermined area including the position of the center axis, and a plurality of hollow parts formed around the solid part It is characterized by extending in the above-mentioned extending direction. In addition, the racket wire of the present invention is provided with a core wire and a plurality of side wires wound around the outer side of the core wire. The core wire includes: a solid part formed at a position including a central axis The predetermined area and the plurality of hollow portions are formed around the solid portion and extend in the extending direction of the above-mentioned core line.

According to these configurations, the center axis position becomes a solid part, and a hollow part is formed around the solid part. Therefore, by stretching and hitting the racket, strong force from the radial direction of the net line (thickness direction) ) Both sides In the hollow section. Thereby, the hollow portion is not easily crushed, and not only advantages such as vibration absorption effect at impact can be obtained, but also stress concentration caused by crushing can be prevented from increasing and durability reduction can be prevented. In addition, a plurality of hollow parts are formed around the solid part, which not only maintains the total opening area of the hollow parts, but also reduces the opening areas of the respective hollow parts, which also makes it difficult to crush the hollow parts.

In addition, in the net string for a racket of the present invention, the number of the hollow portions may be an odd number, and they may be arranged at equal angles centered on the solid portion. According to this configuration, the hollow parts are arranged around the solid part while being scattered, and the two hollow parts can not be arranged in the diameter direction of the mesh wire. Thereby, even if a force from the diameter direction is applied to one of the plurality of hollow parts and crushed by stretching the racket or the like, it is possible to suppress a large force from the diameter direction from acting on the other hollow parts. As a result, the two hollow portions can be prevented from being crushed at the same time, and the advantages of the hollow portion can be more easily and well utilized.

In addition, in the net string for a racket of the present invention, the number of hollow portions formed may be one of 3, 5, and 7. According to this structure, the size and arrangement of the hollow portion can be maintained in a well-balanced manner, the stress concentration on the hollow portion can be more relieved to improve durability, the state of forming the hollow portion can be maintained, and the advantages of the hollow portion can be well utilized.

In addition, in the string for a racket of the present invention, the plurality of hollow portions may be formed in the same shape. According to this configuration, even if the direction of the surrounding direction of the net line is changed, the performance related to the shot of the hollow portion can be stabilized without changing.

In addition, the string for the racket of the present invention occupies the racket The ratio of the opening area of the hollow portion in the entire cross section of the mesh wire may be 3.0% or more and 8.0% or less. With this range of values, it is possible to achieve both the improvement of the disconnection durability and the improvement of the hitting feeling that form the opposite relationship.

According to the present invention, a solid part is formed at the central axis position, and a plurality of hollow parts are formed around the solid part. Therefore, the advantages of forming the hollow part can be obtained and durability can be improved.

10‧‧‧Network cable

10A‧‧‧Network cable

11‧‧‧heart line

11A‧‧‧heart line

11a‧‧‧Groove

12‧‧‧Side line

13‧‧‧Resin coating

20‧‧‧Solid part

21‧‧‧Hollow part

21A‧‧‧Hollow part

31‧‧‧Hollow part

C‧‧‧Center axis position

Figure 1 is a cross-sectional view of the mesh line related to the first embodiment.

Figure 2 is a cross-sectional view of the mesh lines related to the comparison structure.

Figure 3 is a cross-sectional view of the mesh line related to the second embodiment.

Fig. 4 is a graph showing the relationship between the hollow ratio of the network cable, the natural frequency of vibration, and the breaking strength.

Figure 5 is a graph showing the relationship between the specifications of the network cable and the natural frequency.

Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In addition, the net string of the present invention can be applied to various rackets such as soft tennis, tennis, badminton, and squash as long as it is stretched on the frame of the racket to form a racket surface.

[First Embodiment]

Figure 1 is a cross-sectional view of the mesh line related to the first embodiment. As shown in Fig. 1, the mesh wire 10 is a core wire 11 with a cross section at the center forming a circular outer periphery; a plurality of side wires 12 spirally wound around the outer side of the core wire 11; and further formed on the periphery thereof The three-layer structure constituted by the resin coating 13 has a circular cross-section. The heart thread 11 and the side thread 12 are integrally adhered with an adhesive.

The core thread 11 is a monofilament made of synthetic fibers, preferably nylon 6 and nylon 66 polyamide fibers. And for the side thread 12, a monofilament, a multifilament, or a multi-monofilament made of synthetic fibers is used, preferably nylon 6 and nylon 66 polyamide-based fibers. The resin coating layer 13 preferably uses polyamide resin. In addition, polyester (polybutylene terephthalate, polyethylene terephthalate, etc.), polyolefin, polyphenylene sulfide, polyether ether ketone, etc. can also be used for the core wire 11 and the side wire 12.

The core wire 11 includes a solid portion 20 formed in a predetermined area including the central axis position C, and a plurality of hollow portions 21 formed around the solid portion 20. In other words, in the core line 11, as indicated by the two-dot dashed line in FIG. 1, the area where the cross section inside the plurality of hollow portions 21 is substantially circular forms the solid portion 20. The solid portion 20 and the plurality of hollow portions 21 are respectively formed to extend in the extending direction of the core wire 11.

The number of hollow portions 21 formed is an odd number. In the first embodiment, five hollow portions 21 are formed. The five hollow portions 21 are arranged at equal angles (each approximately 72°) with the solid portion 20 as the center. Therefore, all hollow The part 21 is formed on the line L (dotted line in Figure 1) connecting the hollow parts 21 and the central axis position C so that there are no other hollow parts 21, and any hollow parts 21 are not arranged in plural in the center. The radial direction of line 11.

The five hollow portions 21 are formed in substantially the same circumferential shape, and the first embodiment is formed in a substantially quadrangular shape in cross section. Specifically, it is provided with two sides forming a substantially right-angled internal angle, and two sides forming an obtuse internal angle at the opposite corners thereof, and are formed in an elongated shape that tapers toward the radially outer side of the center line 11. In addition, the five hollow portions 21 are formed to be approximately the same distance from the central axis position C, and the distance from the outer periphery of the core wire 11 is also approximately the same.

The ratio of the opening area (total) of all the hollow portions 21 occupying the entire cross section of the mesh wire 10 (hereinafter referred to as the "hollow ratio") is preferably set to 3.0% or more and 8.0% or less, and the reason will be described later.

Next, the deformation of the hollow portion 21 when the mesh cable 10 is stretched will be described while comparing it with the comparative structure in FIG. 2.

Once the net wire 10 is stretched on a racket frame (not shown) in a mesh shape, it receives a tensile force in the extending direction. At the same time, the intersecting part of the longitudinal and transverse lines stretched in a mesh shape is subjected to the compressive force from both sides of the diameter direction in the cross section. In addition, when hitting the ball with a racket, the net line 10 also receives a compressive force from both sides in the diameter direction in the cross section. Such a compressive force for the mesh wire 10, as long as it is in the diameter direction in the cross section, will have various effects due to changes in the direction of the surrounding direction of the stretched mesh wire 10. Here, consider the case where the compressive force acts in the direction of arrow F in Figure 1 as one example.

When the relevant compressive force acts, the uppermost hollow portion 21 in Figure 1 is crushed and deformed in the vertical direction in the diameter direction. However, since the other four hollow portions 21 are not located on the line of the arrow F on which the compressive force acts, the compressive force acting becomes extremely weak, and the deformation of the hollow portion 21 can be suppressed. That is, the four hollow parts 21 not on the line of the arrow F can maintain the open state. In addition, even if the diameter position where the compression force acts is changed, since the two hollow parts 21 are not arranged in the diameter direction, at least four hollow parts 21 can maintain the open state as described above.

In addition, in the uppermost hollow portion 21, the compressive force from below acts through the solid portion 20. Therefore, the force of crushing and deforming the hollow portion 21 is dispersed by the solid portion 20, and it can be estimated that the amount of crushing deformation becomes smaller. In addition, with respect to the compressive force from above, the solid portion 20 acts like a frame to support the uppermost hollow portion 21, and it is estimated that the uppermost hollow portion 21 becomes difficult to collapse. Therefore, even the uppermost hollow portion 21 can be suppressed from being collapsed and deformed.

Here, the five hollow portions 21 are formed at about 72° in the cross section centered on the axis center position C, and have the same shape. Therefore, the compressive force acting position indicated by the arrow F in Figure 1 is approximately When the multiple of 72° is changed, the hollow portion 21 is deformed in the same manner as described above. Depending on the change in the diameter position where the compression force acts, all the hollow portions 21 may overlap the diameter positions. In this case, the crushing deformation of the hollow portion 21 can be suppressed more satisfactorily.

Figure 2 is a cross-sectional view of the mesh lines related to the comparison structure. The network cable 10A related to the comparative structure is a modification of the network cable 10 of the first embodiment The forming position and shape of the hollow portion 21 is formed by forming a hollow portion 21A at the axial center position C of the core wire 11A. When the wire 10A of such a comparative structure has a compressive force acting in the direction of arrow F as described above, the two-dot dashed line in the figure indicates that the hollow portion 21A is flat and crushes both sides in the vertical direction (diameter direction). The reason for this may be, for example, that the hollow portion 21A is located at the shaft center position C, and the opening area of the hollow portion 21A is large.

The stress is concentrated on the left and right sides of the crushed hollow portion 21A, causing the stress-concentrated portion to produce cracks, durability and breaking strength, and other adverse effects. In contrast, the mesh cable 10 of the first embodiment can not only maintain the total opening area of each hollow portion 21, but also reduce the opening area, and suppress the crushing of each hollow portion 21 as described above. Therefore, it can suppress the comparison structure The stress is concentrated. In this way, it is possible to avoid the occurrence of cracks in the stress concentration part of the comparative structure, and to improve the performance for durability and breaking strength. As a result, the long life of the network cable 10 can be obtained, and not only can the high performance be maintained for a long period of time, but also the replacement frequency can be reduced, and the cost burden can also be reduced.

Here, as in the above-mentioned mesh wire 10, a plurality of hollow portions 21 are formed in the core wire 11, thereby comparing with a mesh wire in which the core wire 11 without the hollow portion 21 is formed as a solid wire (hereinafter, referred to as "solid mesh wire"), the following description advantage.

By comparing the formation of the hollow part 21 with a solid mesh wire, the size (diameter size) can be made thick without changing the weight per unit length. Thereby, the contact area between the net line 10 and the ball (badminton) can be enlarged, the controllability and driveability can be improved, and the force of hitting the ball can be increased. And, forming a solid network cable In the case of the mesh cable 10 of the same specification, the amount of the plurality of hollows 21 can be realized to improve the easy displacement of the mesh cable 10 and the high rebound force of recovery, and in addition to obtaining a light and sharp good hitting feeling, and Can improve the sound of hitting the ball.

The above advantages are not obtained by a solid wire, and it is not easy to obtain when the hollow part 21A is crushed in a comparative structure. That is, the above-mentioned advantages can be said to be unique and remarkable effects obtained by forming a plurality of hollow parts 21 as in the above-mentioned mesh wire 10.

[Second Embodiment]

Next, the second embodiment which is different from the first embodiment will be described with reference to FIG. 3. Figure 3 is a cross-sectional view of the mesh line related to the second embodiment. In addition, in the second embodiment, the same reference numerals are given to the constituent elements common to the first embodiment, and the description thereof is omitted.

In the mesh wire 10 according to the second embodiment, three hollow portions 31 are formed in the core wire 11. The three hollow portions 31 are arranged with the solid portion 20 as the center at equal angles of approximately 120°. Therefore, in the second embodiment, all the hollow portions 31 also form a positional relationship in which no other hollow portions 31 exist on the line L (dotted line in FIG. 3) connecting the hollow portions 31 and the central axis position C. Any hollow portion 31 is not arranged in plural in the radial direction of the core wire 11.

The three hollow portions 31 are formed in substantially the same circumferential shape, and the second embodiment is formed in a substantially triangular shape in cross section. Specifically, a substantially equilateral triangle shape is formed, and the base is located on the central axis position C side and bends concentrically with the center line 11, and the inner corners of the other two sides It becomes an obtuse angle and is positioned on the radially outer side of the core wire 11. In addition, the three hollow portions 31 are formed to have the same distance from the central axis position C, and the distance from the periphery of the core wire 11 is also set to be the same. The three hollow parts 31 are closer to the central axis position C than the hollow part 21 of the first embodiment, and are formed at positions farther from the outer periphery of the core wire 11.

In addition, the ratio of the opening area (total) of all the hollow portions 31 occupying the entire cross section of the center line 11 is also set to 3.0% or more and 8.0% or less.

On the radially outer side of each hollow portion 31 and on the outer peripheral surface of the core wire 11, a groove 11a formed with a V-shaped cut corner is formed. In addition, the formation of the related groove 11a may be omitted, and the core wire 11 may also form a substantially cylindrical periphery.

According to such a second embodiment, the same effects as those of the first embodiment can be obtained, and the number of hollow portions 31 formed has been reduced. Therefore, a mold and the like can be omitted, and manufacturing can be simplified.

Next, a description will be given of an experiment conducted to evaluate the hitting feeling, hitting sound, and durability of the net line related to the above-mentioned first embodiment. In the experiment, Examples 1 and 2 were used to fabricate the mesh cable of the first embodiment shown in Fig. 1. In Example 1, the hollow ratio of the hollow portion 21 was set to 4.2%, and Example 2 was set to 2.3%. In addition, in the comparative example, a mesh wire in which the core wire 11 is solid is produced. The other conditions are the same as in the respective examples and comparative examples.

For the net cables of Examples 1, 2 and the comparative example, in order to evaluate the feeling and sound of hitting the ball, an experiment was performed to measure the natural frequency of the net line. In addition, for the network cables of Examples 1 and 2, in order to evaluate the durability, measurement was performed Powerful experiment of disconnection of the network cable. The measurement results are shown in Figure 4A and Figure 4B. Fig. 4A and Fig. 4B are graphs showing the relationship between the hollow ratio of the mesh cable, the natural frequency of vibration, and the breaking strength. Figure 4A shows the measurement results of the natural vibration frequency and breaking strength of the wire stretched on the racket for hard tennis. Figure 4B shows the measurement results of the natural vibration frequency and breaking strength of the wire stretched on the soft tennis racket.

In the experiment to measure the natural frequency of the net cable, the net cables of Examples 1, 2 and Comparative Examples were stretched on a hard tennis racket with a tension of 50 pounds, and stretched on a soft tennis racket with a tension of 30 pounds. In addition, an acceleration sensor was installed on the grip of the racket after the stretch, and the output analysis of the acceleration sensor was performed using an FFT analyzer DS-2000 ((stock) Ono Sokki). Use the impact hammer to impact the intersection of the network cable, transform the obtained time axis vibration frequency into Fourier transform, and measure the primary natural vibration frequency of the network cable. The measurement results are shown in Figure 4A and Figure 4B.

In addition, using the rackets with the wires of Examples 1 and 2 and the comparative example, the feeling of hitting and the sound of hitting the ball felt by the players were evaluated. In this evaluation, Example 1 where the above-mentioned hollow rate became 4.2% was the most favorable, and then, Example 2 where the above-mentioned hollow rate became 2.3% was relatively good, while the comparative example and Example 1 were inferior to the player's feeling of hitting and hitting. The change of the natural frequency of the change of the ball sound is about 10 Hz or more. In the graphs of Fig. 4A and Fig. 4B, on the straight line obtained by the least square method from the measurement results of the natural frequency, the hollow ratio of the natural frequency of Example 1 minus 10 Hz is approximately 3%. Therefore, when the above-mentioned hollow ratio becomes 3.0% or more, a high hitting sound and a good hitting feeling can be obtained. and In addition, it can be inferred that the difference between Examples 1 and 2 is caused by the hollow ratio that is not affected by the number of hollow portions formed.

In the experiment for measuring the breaking strength of the mesh cable, the mesh cables of Examples 1 and 2 were measured with autograph AGS-J (manufactured by Shimadzu Corporation). The measurement conditions are based on the JIS L1013: 2010 edition of the "Test Methods for Chemical Fiber Yarns", with the test item gripping interval 250mm, tensile strength 300mm/min, and 3 tests. The measurement results of the average of the three tests are shown in Figure 4A and Figure 4B. The lower limit of the breaking strength that the network cable can withstand in actual use is 300N. In the graphs in Figs. 4A and 4B, the hollow rate is greater than 8% when the breaking strength is less than 300N on the straight line connecting the measurement results of the breaking strength. Therefore, when the above-mentioned hollow ratio becomes 8.0% or less, good disconnection durability can be exhibited. As explained above, when the above-mentioned hollow ratio is 3.0% or more and 8.0% or less, both the improvement of the disconnection durability and the improvement of the hitting feeling can be achieved in the opposite relationship.

Figure 5 is a graph showing the relationship between the specifications of the network cable and the natural frequency. In order to study the relationship between the specifications of the network cable and the presence or absence of the hollow part of the core wire, three types of comparative network cables (the core wire is solid) with specifications of 1.15mm, 1.2mm, and 1.25mm are prepared, and the specification is 1.25mm Example of the network cable. And, similar to the above, it was stretched on a soft tennis racket to measure the natural frequency. The measurement results are shown in Figure 5.

As can be understood from the graph in Figure 5, under the condition of the mesh line of 1.25 mm, compared with the comparative example in which the core line is solid, the measured value of the natural frequency of Example 1 where the core line forms a hollow portion Get bigger. because Therefore, as long as the specifications are the same, the side forming the hollow portion is lighter to obtain a sharp and good hitting feeling, and the hitting sound can be improved.

In addition, in the graph of Fig. 5, a straight line obtained by the minimum multiplication method is drawn from each measurement result of the natural frequency of the comparative example. On this straight line, the specification which is the same as the natural frequency of Example 1 whose specification is 1.25 mm is 1.215 mm. That is, as long as the natural frequency is the same, compared with the comparative example in which the core wire is solid, the side of Example 1 in which the core wire forms a hollow portion can be formed into a thicker specification. Thereby, while maintaining the hitting feeling and sound of hitting, the contact area between the net line and the ball (badminton) can be enlarged.

In addition, the present invention is not limited to the above-mentioned embodiment, and can be implemented with various modifications. In the above-mentioned embodiment, the size, shape, direction, etc. shown in the attached drawings are not limited to these, and can be appropriately changed within the range in which the effects of the present invention are exerted. In addition, it can be implemented with appropriate changes within the scope not departing from the purpose of the present invention.

For example, even if the number of hollow portions 21 and 31 formed in the core wire 11 is seven, the same effects as in the above-described embodiments can be obtained. Also, the number of hollow portions 21, 31 formed can be changed to an even number, but the odd number is arranged at equal angles with the solid portion 20 as the center to avoid not arranging the two hollow portions 21, 31 on the core wire 11 The diametrical direction makes the point where the two hollow parts collapse at the same time is advantageous. In addition, the number of hollow parts 21 and 31 formed may be an odd number of 9 or more. However, the number of formations of 3, 5, and 7 can increase the size and arrangement of the hollow parts 21 and 31 in a balanced manner, and can exhibit good durability And batting performance.

In addition, the opening shapes of the hollow portions 21 and 31 are not limited to those shown in the figure. The illustrated configuration examples can also be changed from the viewpoints of workability, shot performance, and durability.

In addition, in the mesh wire 10, the configuration of all the side wires 12 wound around the core wire 11 may be omitted. In this case, a monofilament made of synthetic fiber is used for the mesh wire 10, and polyester is preferably used. However, nylon 6 and nylon 66 polyamide fibers can also be used.

[Industrial availability]

The net string for a racket of the present invention has the effect of forming a hollow portion on one side and improving durability.

This application is based on Japanese Patent Application 2015-221973 filed on November 12, 2015. All of this content is included here.

10‧‧‧Network cable

11‧‧‧heart line

12‧‧‧Side line

13‧‧‧Resin coating

F‧‧‧Arrow

Line L‧‧‧

Claims (9)

A racket netting line, which is tied to a racket netting line extending in a predetermined direction, is characterized by comprising: a solid part formed in a circular area including a central axis position in a cross section, and a plurality of hollow parts formed in the solid part The periphery of the hollow portion extends in the extending direction and is formed into a substantially quadrangular shape or a substantially triangular shape; the side of the hollow portion on the side of the central axis position in the transverse section is arranged to extend in the circumferential direction of the concentric circles of the solid portion. A racket net wire tied to a racket net wire having a core wire and a plurality of side wires wound around the outer side of the core wire, characterized in that the core wire has: a solid part formed in a cross section including a central axis The circular area of the position and the plural hollow parts are formed on the periphery of the solid part and extend in the extending direction of the above-mentioned core line and are formed into a substantially quadrangular or substantially triangular shape; the cross section of the hollow part is on the side of the central axis The sides are arranged to extend in the circumferential direction of the concentric circles of the solid portion. For example, in the racquet wire described in the first item of the scope of patent application, the number of formation of the hollow portion is an odd number, and the solid portion is arranged at equal angles. For example, in the racquet wire described in the scope of the patent application, the number of formation of the hollow portion is an odd number, and the solid portion is arranged at equal angles. For example, in the net string for a racket described in item 3 of the scope of the patent application, the number of the hollow portion formed is one of 3, 5, and 7. For example, in the net string for a racket described in item 4 of the scope of the patent application, the number of the hollow portion formed is one of 3, 5, and 7. For the racket net string described in any one of items 1 to 6 of the scope of the patent application, the plurality of hollow portions are formed in the same shape. The racket wire described in any one of items 1 to 6 of the scope of patent application, wherein the ratio of the opening area of the hollow portion in the cross section of the entire cross section of the racket wire is 3.0% or more and 8.0% the following. As described in the seventh item of the scope of patent application, the ratio of the opening area of the hollow portion in the cross section of the entire cross-section of the racket wire is 3.0% to 8.0%.

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