JP4218871B2 - String protector and tennis racket provided with the string protector - Google Patents

Description

【００３７】
「実施例１」
ラケットフレームは、カーボン繊維を補強繊維とし、エポキシ樹脂をマトリクス樹脂としたプリプレグを積層して予備成形体（レイアップ）を形成し、これを金型に配置し、１４５℃、５０分間の条件で成形した。内圧は７ｋｇｆ／ｃｍ²とした。
成形したラケットフレームは、厚み２８ｍｍ、長さは２７．５インチ、ヘッド部に囲まれるフェイス面積（打球面積）は１１５ｉｎｃｈ²とした。
切れ込みを設けたストリング保護材および粘弾性材からなる振動減衰材は上記第１実施形態と同様とした。
ストリングには、バボラ社の合成繊維からなるストリングである「ＡＴＰツアークラシック」（ゲ−ジ：１．３５ｍｍ）を使用し、テンションは縦糸５０１ｂ×横糸４５１ｂとした。
【００３８】
「実施例２」
切れ込みを設けたストリング保護材および粘弾性材からなる振動減衰材をヘッド部の２時及び４時部分に配置した。２時部分に配置したストリング保護材の帯分の長さを９０ｍｍとし、４時部分に配置したストリング保護材の帯部の長さを８５ｍｍとした。他の構成は実施例１と同様とした。
「実施例３」
切れ込みを設けたストリング保護材及び粘弾性材からなる振動減衰材はヨークには設けず、ヘッド部の３時部分（９時部分）にのみ配置した。他の構成は実施例１と同様とした。
「実施例４」
ストリング保護材にＡＴＯ社のＲＩＬＳＯＮ（ＢＭＮ）を使用し、筒状部の厚さを２．４ｍｍとした。他の構成は実施例３と同様とした。
「実施例５」
ストリング保護材にＰＥＢＡＸ５５３３を使用し、筒状部材の厚さを０．７ｍｍとした。他の構成は実施例３と同様とした。
「実施例６」
粘弾性材は実施例１の粘弾性材に使用した物質にハイブラーＶＳ−１を２０重量部追加したゴム組成物を架橋して成形した。粘弾性材の厚さを０．６ｍｍとした。ショアＡ硬度は９２であった。他の構成は実施例３と同様とした。
「実施例７」
粘弾性材にハイトレルを使用した。他の構成は実施例３と同様とした。
「実施例８」
ストリング保護材として６ナイロンを使用し、筒状部材の厚さを２．７ｍｍとした。他の構成は実施例３と同様とした。
「実施例９」
ストリング保護材としてセプトン２０６３を使用し、筒状部材の厚さを０．５ｍｍとした。他の構成は実施例３と同様とした。
「実施例１０」
ストリング保護材の切れ込み長さを変更したこと以外は、実施例３と同様とした。切れ込みの長さを５ｍｍとした。
「実施例１１」
切り込みの長さを１３ｍｍとしたこと以外は実施例３と同様とした。
「実施例１２」
切り込みの長さを２ｍｍとしたこと以外は実施例３と同様とした。
「実施例１３」
切り込みの長さを１７ｍｍとしたこと以外は実施例３と同様とした。
「実施例１４」
粘弾性材を配置しなかった。他の構成は実施例３と同様とした。
【００３９】
「比較例１」
ストリング保護材に切れ込みを設けず、粘弾性材を配置しなかった。他の構成は実施例３と同様とした。
「比較例２」
ストリング保護材に切れ込みを設けなかった。他の構成は実施例３と同様とした。
【００４０】
［反発係数の測定］
反発係数は、図５に示すように、実施例１〜１４及び比較例１、２のテニスラケットに、各テニスラケットを垂直状態でフリーとなるようにグリップ部を柔らかく固定し、その打球面にボール打出機から一定速度Ｖ１（３０ｍ／ｓ）でテニスボールを打球面に衝突させ、跳ね返ったボールの速度Ｖ２を測定した。反発係数は発射速度Ｖ１、反発速度Ｖ２の比（Ｖ２／Ｖ１）であり、反発係数が大きい程、ボールの飛びが良いことを示している。このような方法で、打球面上で反発係数が最大となる最大反発位置を求め、最大反発係数を測定した。
【００４１】
［面外１次振動減衰率の測定］
実施例１〜１４及び比較例１、２のテニスラケットを図６（Ａ）に示すようにヘッド部１２の上端を紐５１で吊り下げ、ヘッド部１２とスロート部１３との一方の連続点に加速度ピックアップ計５３をフレーム面に垂直に固定した。この状態で、図６（Ｂ）に示すように、ヘッド部１２とスロート部１３の他方の連続点をインパクトハンマー５５で加振した。インパクトハンマー５５に取り付けられたフォースピックアップ計で計測した入力振動（Ｆ）と加速度ピックアップ計５３で計測した応答振動（α）をアンプ５６Ａ、５６Ｂを介して周波数解析装置５７（ヒューレットパッカード社製、ダイナミックシングルアナライザーＨＰ３５６２Ａ）に入力して解析した。解析で得た周波数領域での伝達関数を求め、テニスラケットの振動数を得た。振動減衰比（ζ）は下式より求め、面外１次振動減衰率とした。
【００４２】
ζ＝（１／２）×（Δω／ωｎ）
Ｔｏ＝Ｔｎ／√２
【００４３】
［面外２次振動減衰率の測定］
実施例１〜１４及び比較例１、２のテニスラケットを図６（Ｃ）に示すようにヘッド部１２上端を紐５１で吊り下げ、スロート部１３とシャフト部１４との連続点に加速度ピックアップ計５３をフレーム面に垂直に固定した。この状態で、加速度ピックアップ計５３の裏側のフレームをインパクトハンマー５５で加振した。そして、面外１次振動減衰率と同等の方法で減衰率を算出し、面外２次振動減衰率とした。
【００４４】
［耐久テスト方法］
実施例１〜１４及び比較例１、２のテニスラケットのグリップ部を、ゴムホースを介在させて固定し、ボールを７０ｍ／ｓｅｃのスピードで、ヘッド部１２のトップから１０ｃｍの箇所に衝突させた。３本中１本もストリング保護材が破損しなかった場合を○、１本でも亀裂等が生じた場合を△、破断した場合を×とした。
【００４５】
表１に示すように、実施例１〜１４と比較例１、２を比較することにより、切れ込みを設けたストリング保護材と粘弾性材からなる振動減衰材をテニスラケットに取り付けることにより、反発性能および振動減衰性能が向上することが確認できた。
【００４６】
実施例１と実施例２、３を比較することにより、切れ込みを設けたストリング保護材と粘弾性材の設置位置によって、反発性能および振動減衰性能が変化することが確認でき、また、打球面を時計面としたときの３時部分、９時部分とヨークに設置するのが好ましいことが確認できた。
実施例３〜５、８、９をそれぞれ比較することにより、ストリング保護材の厚さは耐久性の面から０．６ｍｍ〜２．５ｍｍとするのが好ましく、反発性能、振動減衰性能の面から１．２ｍｍとするのが最適であることが確認できた。
【００４７】
実施例３、１０〜１３をそれぞれ比較することにより、ストリング保護材に設ける切れ込みの長さは、耐久性の面から１５ｍｍ以下であることが好ましく、反発性能、振動減衰性能の面から３ｍｍ以上であることが好ましいことが確認できた。
【００４８】
【発明の効果】
以上の説明より明らかなように、本発明によれば、ラケットフレームに取り付けるストリング保護材の帯部から筒状部にかけてストリング挿通用の貫通穴を設けると共に帯部から筒状部にかけて切れ込みを設けることにより、筒状部が大きく変形するため反発性能を向上させることができる。
また、帯部のうちで、ストリングによる負荷が加わる部分とは独立性の高い状態となっているストリングによる負荷が加わらない部分は、打球時に発生するフレーム振動に合わせた変形が可能となり、ストリング保護材がフレームにとって動吸振器となる。これにより、振動減衰性能をより向上させることができる。
【００４９】
また、ストリング保護材とラケットフレームとの間に粘弾性材からなる振動減衰材を介在させることにより、さらに、振動減衰性能を大幅に向上させることができる。
【図面の簡単な説明】
【図１】 本発明のラケットフレームにストリングを張設した状態を示す部分正面図である。
【図２】 （Ａ）は第１実施形態のストリング保護材と粘弾性材とを取り付ける方法を示す図面、（Ｂ）はストリング保護材の要部拡大平面図、（Ｃ）は粘弾性材の平面図である。
【図３】 ラケットフレームに粘弾性材とストリング保護材を取り付けた状態を示す斜視図である。
【図４】 第２実施形態のストリング保護材の正面図である。
【図５】 最大反発係数の測定試験方法を示す図面である。
【図６】 （Ａ）（Ｂ）（Ｃ）は振動測定方法を示す図である。
【図７】 従来例を示す図面である。
【図８】 他の従来例を示す図面である。
【符号の説明】
１０ ラケットフレーム
１２ ヘッド部
１３ スロート部
１４ シャフト部
１７ ヨーク
２０ ストリング保護材
２０ａ 切れ込み
２１ 帯部
２２ 筒状部
３０ 粘弾性材からなる振動減衰材
Ｆ 打球面
Ｓ ストリング[0001]
[Technical field to which the invention belongs]
The present invention relates to a string protective material and a tennis racket provided with the string protective material, and more particularly, in a light weight racket, the string protective material is improved to improve resilience performance, shock absorption and vibration damping. It is.
[0002]
[Prior art]
In recent years, tennis rackets are molded from fiber reinforced resin, and the length and weight have been dramatically improved. However, due to weight reduction, the impact generated at the time of ball impact is increased, causing unpleasant vibrations and being easily transmitted to the elbow, causing tennis elbows (so-called “tennis elbow”). Furthermore, there is a problem that the resilience decreases as the light weight racket.
[0003]
In order to solve the above problems, various tennis rackets improved in order to improve shock absorption are provided. For example, in Japanese Patent Laid-Open No. 8-107951, as shown in FIG. A tennis racket is provided in which the through hole 3 is provided in the belt-like portion (base portion) 2 to improve the absorbability of the shock transmitted from the string.
Further, in Japanese Utility Model Laid-Open No. 5-35161, as shown in FIG. 8, a hollow portion 6 is provided in the base portion 5 in which the cylindrical body of the string protective material 4 is continuously provided, and the impact received by the string is absorbed by the hollow portion 6. Thus, a tennis racket having improved absorbability of shock transmitted from the string is provided.
[0004]
[Problems to be solved by the invention]
However, the tennis racket disclosed in Japanese Patent Application Laid-Open No. 8-107951 is not configured to deform the string protector 1 itself at the time of hitting, and therefore, the resilience cannot be improved and the vibration of the string is taken into consideration. However, there is a problem that the vibration absorption of the racket frame itself is not considered. Similarly, in the tennis racket of Japanese Utility Model Laid-open No. 5-35161, since the deformation of the string protective material 4 at the time of hitting is not taken into consideration, high resilience cannot be obtained, and the vibration absorption of the racket frame itself is not good. It is enough.
[0005]
The present invention has been made in view of the above problems, and aims to achieve both improvement in resilience performance and improvement in shock absorption and vibration damping in a tennis racket that has been reduced in weight.
[0006]
[Means for Solving the Problems]
  In order to solve the above-mentioned problem, the present invention has a cylindrical part protruding from the band part with a space therebetween, and a string insertion through-hole is provided in the cylindrical part from the band part serving as a base part of the cylindrical part. A string protector made of resin,
  Above base partWhenThe cylindrical partA continuous notch, the notch of the cylindrical part is a 3-15 mm notch parallel to the through hole,
  And the thickness of the said cylindrical part shall be 0.6-2.5 mmA string protective material is provided.
[0007]
Usually, if the string protector is low in rigidity and strength, the cylindrical part that protrudes from the racket frame is greatly deformed by string tension, and problems such as damage to the cylindrical part tend to occur. The string protection material requires a predetermined rigidity or more. Thus, since the string protective material has rigidity, it is not easily deformed at the time of hitting the ball. Therefore, in the conventional string protective material, the string protective material is deformed at the time of hitting and the resilience is enhanced by the spring effect by the deformation. I can't.
However, in the configuration of the present invention described above, since the notch is provided from the band portion of the string protective material to the cylindrical portion, the string is easily movable in the cylindrical portion at the time of hitting, so that high resilience performance can be obtained. .
In addition, since the through hole for inserting the string is provided from the band part of the base part of the cylindrical part and the above-mentioned notch is made in the through hole, the part to which the string load is applied and the string in the band part The parts where no load is applied are highly independent. Therefore, in the belt part, the part that is not subject to the string load that is highly independent of the part to which the string load is applied can be deformed in accordance with the frame vibration that occurs at the time of hitting the string, thereby protecting the string. The material becomes a dynamic vibration absorber for the frame. Thereby, the vibration of the racket frame can be greatly suppressed.
[0008]
The string protective material is preferably molded from a thermoplastic resin such as polyamide resin having good vibration damping properties, and specific examples include nylon 11, nylon 12, polyether block amide, and the like.
When the string protective material is molded from the above resin, the necessary hardness can be imparted to the string protective material, and the flexibility necessary to obtain the spring effect can be imparted.
[0009]
Further, the hardness index of the string protective material is preferably designed to match the vibration frequency (150 to 1,000 Hz) of the string and the frame when the ball is hit. Therefore, the string protective material has a complex elastic modulus E * of dynamic viscoelasticity at −5 ° C. measured at a frequency of 10 Hz is 0.6 × 10 6.⁸~ 2.0 × 10^Tendyn / cm²It is preferable to mold with a resin in the range.
[0010]
That is, since it is difficult to measure the frequency of the resin itself as the string protective material, the complex elastic modulus E * of the dynamic viscoelasticity of the resin is measured at 10 Hz, and the conversion law (empirical rule) of temperature and frequency is used. Have been identified. In the case of the frequency of 10 Hz, when converted to use conditions at a normal temperature (25 ° C.), it corresponds to −5 ° C. This is obtained by superimposing the curve of dynamic viscoelasticity data when the frequency is fixed and the temperature is changed and the curve when the frequency is changed.
As a result, as described above, the complex elastic modulus E * of dynamic viscoelasticity at −5 ° C. measured at a frequency of 10 Hz is 1.0 × 10⁸~ 2.0 × 10^Tendyn / cm²Is preferable, and more preferably 3.0 × 10⁹~ 2.0 × 10^Tendyn / cm²Range.
The complex elastic modulus E * of the dynamic viscoelasticity is 2.0 × 10^Tendyn / cm²If it is larger, the deformation of the string protective material due to the load at the time of hitting is small, so that a sufficient spring effect cannot be obtained and the resilience performance is not improved. Moreover, it is because a crack is easy to enter into the notch of a string protective material, and it becomes easy to break. Furthermore, the frequency of the dynamic vibration absorber becomes too large, and the vibration damping property of the racket frame is lowered. On the other hand, the complex elastic modulus E * of the dynamic viscoelasticity is 1.0 × 10.⁸dyn / cm²If it is smaller, stress concentration occurs on the racket frame, and the racket frame is easily damaged. Further, buckling deformation occurs at the time of hitting a ball, so that an optimal spring effect cannot be obtained.
[0011]
  The cylindrical part has a thickness of 0.6 to 2.5 mm.is doing.
  This is because if the thickness of the cylindrical portion is smaller than 0.6 mm, sufficient strength cannot be imparted to the string protective material, and the strength of the racket frame cannot be maintained, and is larger than 2.5 mm. This is because the cylindrical portion is difficult to deform and sufficient resilience performance cannot be obtained.
[0012]
  The length of the cut is 3 to 15 mm.AndMore preferably, it is 5-12 mm. If the length of the cut is shorter than 3 mm, each cylindrical portion cannot obtain sufficient independence, and the effect on high resilience and high vibration damping is reduced. On the other hand, if the length is longer than 15 mm, the strength of the cylindrical portion is reduced, and therefore, the cylindrical portion is easily damaged, and the cylindrical portion is greatly deformed, so that it is easy to contact the racket frame and unpleasant vibration sound is generated.
[0013]
It is preferable that six or more cylindrical portions are provided in the band portion.
In addition, at least some of the cylindrical portions may be provided with the notches extending from the base portion to the tip of the cylindrical portion over the entire length of the through hole.
Even with the above configuration, high resilience and high vibration damping can be obtained as in the case where the string protective material is cut.
[0014]
The present invention provides a tennis racket characterized in that the string protective material is fitted in a string groove provided in a racket frame surrounding a hitting surface.
[0015]
When the spring protector is attached to the tennis racket, the string protector is notched, so that the tubular portion is easily deformed and a tennis racket with excellent resilience performance can be obtained. In addition, as described above, the portion of the belt portion that is not subjected to the load due to the string that is highly independent of the portion that is subjected to the load due to the string is deformed in accordance with the frame vibration generated at the time of hitting the ball. The string protector becomes a dynamic vibration absorber for the frame. Thereby, a frame vibration can be suppressed greatly and it can be set as the tennis racket excellent in vibration damping performance.
[0016]
A vibration damping material having a viscoelastic material made of rubber, elastomer or resin having a lower elastic modulus than that of the string protective material and having a substantially band shape is interposed between the racket frame and the band portion of the string protective material.
It is preferable that the vibration damping material is in sufficient contact with the string protective material and the racket frame.
[0017]
As described above, when a vibration damping material made of a viscoelastic material is interposed between the band portion of the string protective material and the racket frame, it is possible to suppress the vibration of the string wound around the band portion from being transmitted to the racket frame. . Further, adjustment for deformation at the time of ball hitting becomes easy.
In addition, the string protective material is notched so that each cylindrical part behaves almost independently, and a vibration damping material made of a viscoelastic material is interposed to adjust the rigidity of the viscoelastic material. Thus, the amount of deformation of each cylindrical portion at the time of hitting the ball can be adjusted, and stable dynamic vibration absorber performance can be obtained.
[0018]
The viscoelastic material serving as the vibration damping material has a complex elastic modulus E * of dynamic viscoelasticity at −5 ° C. measured at a frequency of 10 Hz of 1.5 × 10 5.⁷~ 5.0 × 10⁹dyn / cm²It is preferable to set it as the range. More preferably, 5.0 × 10⁸~ 5.0 × 10⁹dyn / cm²Range.
The complex elastic modulus E * of the dynamic viscoelasticity of the viscoelastic material is 5.0 × 10⁹dyn / cm²If it is larger, the deformation amount at the time of hitting the ball is small and the spring effect cannot be obtained, and the spring constant as the dynamic vibration absorber is too large, and the dynamic vibration absorber effect is reduced.
The complex elastic modulus E * of the dynamic viscoelasticity is 1.5 × 10⁷dyn / cm²If it is smaller, the deformation at the time when the string is stretched is large, the spring effect at the time of hitting the ball is not obtained, and the spring constant is too small, so that it does not match the frequency of the dynamic vibration absorber.
[0019]
Specific examples of the viscoelastic material serving as the vibration damping material include the following materials.
What added the block copolymer which polystyrene and vinyl polyisoprene couple | bonded with respect to 100 weight part rubber | gum material in 5-80 parts. As the block copolymer in which polystyrene and vinyl polyisoprene are bonded, Kuraray's “Hibler” is preferably used.
In addition to the block copolymer in which polystyrene and vinyl polyisoprene are bonded to each other, there are various other mature plastic resins. For example, PR-12686 of Sumilite resin is preferably used.
Base rubber includes natural rubber, butyl rubber, acrylonitrile butadiene rubber, etc. Instead of adding the above-mentioned mature plastic resin, it is also effective to increase the amount of carbon black than usual and add 60 to 120 parts It is.
[0020]
Further, a modified thermoplastic resin or rubber is also preferably used.
For example, polyvinyl chloride, polyethylene, polypropylene, ethylene vinyl acetate copolymer, polymethyl methacrylate, polyvinylidene fluoride, polyisoprene, polystyrene, styrene-butacidiene-acrylonitrile copolymer, styrene-acrylonitrile copolymer, NBR, Polymer materials such as SBR, butadiene rubber, natural rubber, and isoprene rubber, and blends thereof can be used. Mica, glass fragments, class fibers, carbon fibers, calcium carbonate, barlite, precipitated barium sulfate, and other substances, corrosion inhibitors, dyes, antioxidants, stabilizers, wetting agents, etc. are added to these as needed. Can be added.
[0021]
What mix | blended the active component which increases the amount of dipole moments with the component which comprises the said base material is preferable.
An active ingredient is one whose active ingredient itself has a large amount of dipole moment, or whose active ingredient itself has a small dipole moment, but by adding the active ingredient, the dipole moment in the base material is dramatically increased. An ingredient that can be used. Specifically, cyclohexane, benzothiazol, dicyclohexylamine, cyclohexylaniline, higher fatty acids and the like are mixed and used as the active ingredient.
[0022]
When a thermoplastic resin is used, the heat distortion temperature is preferably 110 ° C. or higher. This is because the tennis racket may be left in the vehicle while maintaining the load from the string, and it is necessary to withstand the string load and heating.
It is also preferable that the loss coefficient tan δ of the viscoelastic material is large. This is because a larger tan δ is more effective for the dynamic vibration absorber function.
[0023]
The string protective material is preferably attached to the 3 o'clock portion and the 9 o'clock portion and the yoke when the entire circumference of the ball striking surface of the tennis racket or the ball striking surface is the clock face and the top position of the ball striking surface is 12 o'clock.
A sufficient rebound performance and a high vibration damping performance can be obtained not only when it is attached to the entire circumference but also when it is attached only to the 3 o'clock portion and 9 o'clock portion and the yoke.
[0024]
Moreover, it is preferable that the said string protection material attaches what provided six or more cylindrical parts in one strip | belt part in the above-mentioned position.
If it is set as the said structure, a resilience performance and a vibration damping performance can be improved effectively, and also a high resilience function and a dynamic vibration damper function can be made compatible.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a first embodiment of the present invention. A racket frame 10 (hereinafter abbreviated as a frame 10) is composed of a continuous pipe made of fiber reinforced resin, and the frame 10 allows the head portion 12 and the throat to be formed. A portion 13, a shaft portion 14, and a grip portion (not shown) are continuously formed, and both ends of the yoke 17 are connected to the throat portions 13 on both sides to surround the hitting surface F together with the head portion 12.
[0026]
A string groove 18 is provided on the outer peripheral surface side of the head portion 12 and the yoke 17, and a string hole 19 is formed at a predetermined interval from the bottom surface of the string groove 18 to the inner peripheral surface of the head portion 12 and the yoke 17. ing.
FIG. 2A shows the string protective material 20, which is attached to the outer peripheral surfaces of the head portion 12 and the yoke 17.
Further, a substantially band-shaped vibration damping material 30 made of a viscoelastic material between the string protection material 20 and the frame 10 is interposed.
[0027]
The string protection member 20 has a cylindrical portion 22 protruding from the string hole 19 integrally formed at a required interval with a band portion 21 fitted in the string groove 18. The string protection member 20 shown in FIG. 2A is attached to the 3 o'clock (9 o'clock) portion when the hitting surface F is a clock face and the top position is 12 o'clock when attached to the frame 10. The length is 120 mm, and eight cylindrical portions 22 are provided.
When the string protection member 20 is attached to the yoke 17, the length of the belt portion 21 is set to 60 mm, and six cylindrical portions 22 are provided.
[0028]
A string insertion through-hole 23 that is continuous from the band portion 21 corresponding to the base portion of the tubular portion 22 to the hollow portion of the tubular portion 22 is provided.
A pair of cuts 20a parallel to the through hole 23 are formed at opposite positions from the band portion 21 to approximately a half of the length of the cylindrical portion 22 in the longitudinal direction. The cylindrical portion 22 has a thickness of 0.6 mm to 2.5 mm, and is 1.2 mm in the embodiment shown in FIG. The length of the notch 20a is 3 mm to 15 mm, and in this embodiment is 9 mm.
Further, the band portion 21 is provided with a concave portion 21a for fitting a convex portion 32 protruding from the viscoelastic material 30.
[0029]
The string protective material 20 has a complex elastic modulus E * of dynamic viscoelasticity at −5 ° C. measured at a frequency of 10 Hz of 0.6 × 10⁸~ 2.0 × 10^Tendyn / cm²In this embodiment, E * is 1.47 × 10^Tendyn / cm²The resin is molded. In this embodiment, it is molded using RILSON (BMN-P40) manufactured by ATO which is 12 nylon.
[0030]
As shown in FIG. 2C, the band-shaped vibration absorbing material 30 made of the viscoelastic material is provided with holes 31 through which the cylindrical portions 22 of the string protection material 20 pass at predetermined intervals. A convex portion 32 is provided on the surface. The inner peripheral surface of the hole 31 has a size to be brought into contact with the cylindrical portion 31 and a thickness of 1.4 mm in the present embodiment.
[0031]
The vibration damping material 30 made of the viscoelastic material is molded from rubber, elastomer or resin having a lower elastic modulus than the string protective material 20. The complex elastic modulus E * of dynamic viscoelasticity at −5 ° C. measured at a frequency of 10 Hz is 1.5 × 10⁷~ 5.0 × 10⁹dyn / cm²The range is as follows.
[0032]
In this embodiment, it is molded from the following composition, and the above E * is 1.53 × 10 6.⁹dyn / cm²Therefore, the dynamic loss coefficient tan δ is set to 0.47.
The composition has 100 parts by weight of butyl rubber (trade name “IIR268” manufactured by Nippon Synthetic Rubber Co., Ltd.), 60 parts by weight of ISAF carbon black (trade name “Diamond I” manufactured by Mitsubishi Chemical Corporation), polystyrene block and vinyl-polypropylene block. 20 parts by weight of a triblock copolymer (Kuraray's trade name “HIBLER HVS-3”), 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, 1 part by weight of sulfur, a vulcanization accelerator (Ouchi Shinsei Chemical's A rubber composition comprising 1.5 parts by weight of a trade name “Noxeller TET”) and 1 part by weight of another vulcanization accelerator (trade name “Noxeller CZ” of Ouchi Shinsei Chemical Co., Ltd.). Cross-linked and molded to have a Shore A hardness of 90.
[0033]
The string protection member 20 is attached to the string groove 18 provided in the head portion 12 and the yoke 17 with the vibration damping material 30 interposed between the frame portion 10 and the cylindrical portion 22 is inserted into the string hole 19. .
In the string S, the string protection member 20 is stretched over the outer surface of the band portion 21 through a through hole 23 extending from the cylindrical portion 22 to the band portion 21.
[0034]
FIG. 4 shows a second embodiment of the present invention. Of the cylindrical members 22 ′ of the string protection member 20 ′, a cut 20a ′ is cut into a part of the cylindrical members 22A ′ from the belt portion 21 ′ to the cylindrical portion 22A. It is provided up to the tip of ', and the cylindrical portion 22' has a divided shape.
Since other configurations are the same as those of the first embodiment, description thereof is omitted.
[0035]
"Example"
As shown in Table 1 below, Examples 1 to 14 and Comparative Example 1 in which the specifications of the notch length, material, installation location, viscoelastic material, thickness, loss tan δ, and the like of the string protective material are different. 2 was produced.
The string protectors of Examples 1 to 14 and Comparative Examples 1 and 2 are attached to a tennis racket, the string is stretched, the coefficient of restitution of the tennis racket, the out-of-plane primary vibration and the out-of-plane secondary vibration attenuation rate, and The durability was measured.
The balance in Table 1 means the dimension from the grip end to the position of the center of gravity. For example, 1.47E10 in the complex elastic modulus E * is 1.47 × 10.^Tendyn / cm²Means.
[0036]
[Table 1]

[0037]
Example 1
The racket frame is formed by laminating prepregs made of carbon fibers as reinforcing fibers and epoxy resin as a matrix resin to form a preform (layup), which is placed in a mold and subjected to conditions of 145 ° C. and 50 minutes. Molded. The internal pressure is 7kgf / cm²It was.
The molded racket frame has a thickness of 28 mm, a length of 27.5 inches, and a face area (hitting ball area) surrounded by the head portion is 115 inches.²It was.
The vibration damping material made of the string protective material and the viscoelastic material provided with the cuts is the same as that in the first embodiment.
As the string, “ATP Tour Classic” (Gage: 1.35 mm), which is a string made of Babola synthetic fibers, was used, and the tension was set to warp 501b × weft 451b.
[0038]
"Example 2"
A vibration damping material made of a string protective material and a viscoelastic material provided with a cut was disposed at 2 o'clock and 4 o'clock of the head portion. The length of the band of the string protective material arranged at 2 o'clock is 90 mm, and the length of the string protective material arranged at 4 o'clock is 85 mm. Other configurations were the same as those in Example 1.
"Example 3"
The vibration-damping material made of the string protective material and the viscoelastic material provided with the cut was not provided on the yoke, and was arranged only at the 3 o'clock portion (9 o'clock portion) of the head portion. Other configurations were the same as those in Example 1.
Example 4
RILSON (BMN) manufactured by ATO was used as the string protective material, and the thickness of the cylindrical portion was 2.4 mm. Other configurations were the same as in Example 3.
"Example 5"
PEBAX5533 was used for the string protective material, and the thickness of the cylindrical member was 0.7 mm. Other configurations were the same as in Example 3.
"Example 6"
The viscoelastic material was molded by crosslinking a rubber composition obtained by adding 20 parts by weight of Hibbler VS-1 to the material used for the viscoelastic material of Example 1. The thickness of the viscoelastic material was 0.6 mm. The Shore A hardness was 92. Other configurations were the same as in Example 3.
"Example 7"
Hytrel was used for the viscoelastic material. Other configurations were the same as in Example 3.
"Example 8"
6 nylon was used as the string protective material, and the thickness of the cylindrical member was 2.7 mm. Other configurations were the same as in Example 3.
"Example 9"
Septon 2063 was used as a string protective material, and the thickness of the cylindrical member was 0.5 mm. Other configurations were the same as in Example 3.
"Example 10"
Example 3 was the same as Example 3 except that the cut length of the string protective material was changed. The length of the cut was 5 mm.
"Example 11"
Example 3 was the same as Example 3 except that the cut length was 13 mm.
"Example 12"
Example 3 was the same as Example 3 except that the length of the cut was 2 mm.
"Example 13"
Example 3 was the same as that of Example 3 except that the cut length was 17 mm.
"Example 14"
No viscoelastic material was placed. Other configurations were the same as in Example 3.
[0039]
“Comparative Example 1”
The string protective material was not cut and no viscoelastic material was placed. Other configurations were the same as in Example 3.
“Comparative Example 2”
The string protective material was not cut. Other configurations were the same as in Example 3.
[0040]
[Measurement of coefficient of restitution]
As shown in FIG. 5, the coefficient of restitution is fixed to the tennis rackets of Examples 1 to 14 and Comparative Examples 1 and 2 so that each tennis racket is softly fixed so that it is free in a vertical state. The tennis ball was made to collide with the ball striking surface at a constant speed V1 (30 m / s) from the ball launcher, and the speed V2 of the bounced ball was measured. The restitution coefficient is the ratio (V2 / V1) of the firing speed V1 and the rebound speed V2, and the larger the restitution coefficient, the better the ball flies. By such a method, the maximum restitution position where the restitution coefficient was maximum on the hitting surface was obtained, and the maximum restitution coefficient was measured.
[0041]
[Measurement of out-of-plane primary vibration damping ratio]
As shown in FIG. 6 (A), the tennis rackets of Examples 1 to 14 and Comparative Examples 1 and 2 are hung at the upper end of the head portion 12 with a string 51, and at one continuous point between the head portion 12 and the throat portion 13. The accelerometer 53 was fixed perpendicular to the frame surface. In this state, as shown in FIG. 6B, the other continuous point of the head portion 12 and the throat portion 13 was vibrated with an impact hammer 55. An input vibration (F) measured by a force pickup meter attached to the impact hammer 55 and a response vibration (α) measured by an acceleration pick-up meter 53 are subjected to a frequency analysis device 57 (manufactured by Hewlett-Packard Company, dynamics) through amplifiers 56A and 56B. Single analyzer HP3562A) was input and analyzed. The transfer function in the frequency domain obtained by the analysis was obtained, and the frequency of the tennis racket was obtained. The vibration damping ratio (ζ) was obtained from the following equation, and used as the out-of-plane primary vibration damping rate.
[0042]
ζ = (1/2) × (Δω / ωn)
To = Tn / √2
[0043]
[Measurement of out-of-plane secondary vibration damping ratio]
The tennis rackets of Examples 1 to 14 and Comparative Examples 1 and 2 are hung at the upper end of the head portion 12 with a string 51 as shown in FIG. 6C, and an accelerometer is provided at a continuous point between the throat portion 13 and the shaft portion 14. 53 was fixed perpendicularly to the frame surface. In this state, the frame on the back side of the acceleration pickup meter 53 was vibrated with an impact hammer 55. Then, the attenuation rate was calculated by a method equivalent to the out-of-plane primary vibration attenuation rate, and the out-of-plane secondary vibration attenuation rate was obtained.
[0044]
[Durability test method]
The grip portions of the tennis rackets of Examples 1 to 14 and Comparative Examples 1 and 2 were fixed with a rubber hose interposed therebetween, and the ball was allowed to collide with the 10 cm portion from the top of the head portion 12 at a speed of 70 m / sec. The case where one of the three string protective materials was not damaged was evaluated as ◯, and the case where even one of the cracks was cracked was evaluated as Δ.
[0045]
As shown in Table 1, by comparing Examples 1 to 14 with Comparative Examples 1 and 2, by attaching a vibration dampening material made of a string protective material and a viscoelastic material provided with notches to a tennis racket, the resilience performance It was also confirmed that the vibration damping performance was improved.
[0046]
By comparing Example 1 with Examples 2 and 3, it can be confirmed that the resilience performance and the vibration damping performance change depending on the installation position of the string protective material and the viscoelastic material provided with the notches. It was confirmed that it is preferable to install the watch face on the 3 o'clock portion, 9 o'clock portion and the yoke.
By comparing Examples 3 to 5, 8 and 9, respectively, the thickness of the string protective material is preferably 0.6 mm to 2.5 mm from the viewpoint of durability, from the viewpoint of resilience performance and vibration damping performance. It was confirmed that the optimum value was 1.2 mm.
[0047]
By comparing each of Examples 3 and 10 to 13, the length of the notch provided in the string protective material is preferably 15 mm or less from the viewpoint of durability, and 3 mm or more from the viewpoint of resilience performance and vibration damping performance. It was confirmed that it was preferable.
[0048]
【The invention's effect】
As is clear from the above description, according to the present invention, a string insertion through-hole is provided from the band portion of the string protection member attached to the racket frame to the cylindrical portion, and a notch is provided from the band portion to the cylindrical portion. Thereby, since a cylindrical part deform | transforms greatly, resilience performance can be improved.
Also, in the belt part, the part where the load by the string that is highly independent from the part to which the load by the string is applied can be deformed according to the frame vibration generated at the time of hitting, and the string is protected. The material becomes a dynamic vibration absorber for the frame. Thereby, vibration damping performance can be further improved.
[0049]
Further, the vibration damping performance can be greatly improved by interposing a vibration damping material made of a viscoelastic material between the string protection material and the racket frame.
[Brief description of the drawings]
FIG. 1 is a partial front view showing a state in which a string is stretched on a racket frame of the present invention.
FIGS. 2A and 2B are views showing a method of attaching the string protection material and the viscoelastic material according to the first embodiment, FIG. 2B is an enlarged plan view of the main part of the string protection material, and FIG. It is a top view.
FIG. 3 is a perspective view showing a state in which a viscoelastic material and a string protection material are attached to a racket frame.
FIG. 4 is a front view of a string protection material according to a second embodiment.
FIG. 5 is a drawing showing a test method for measuring the maximum coefficient of restitution.
6A, 6B, and 6C are diagrams illustrating a vibration measurement method.
FIG. 7 is a view showing a conventional example.
FIG. 8 is a view showing another conventional example.
[Explanation of symbols]
10 Racket frame
12 Head
13 Throat
14 Shaft part
17 York
20 String protector
20a notch
21 Belt
22 cylindrical part
30 Vibration damping material made of viscoelastic material
F Hitting surface
S string

Claims (9)

The cylindrical part protrudes with a gap from the band part, and is a resin string protective material provided with a through hole for string insertion from the band part serving as the base part of the cylindrical part to the cylindrical part,
The base portion and the cylindrical portion are provided with a continuous cut, the cut of the cylindrical portion is a 3-15mm cut parallel to the through hole,
And the thickness of the said cylindrical part is 0.6-2.5 mm, The string protective material characterized by the above-mentioned .   The string protective material according to claim 1, wherein the string protective material is formed of a polyamide resin. The complex elastic modulus E * of dynamic viscoelasticity measured at a frequency of 10 Hz at −5 ° C. is molded from a resin having a range of 0.6 × 10 ^{8 to} 2.0 × 10 ¹⁰ dyn / cm ² . The string protective material according to claim 1 or claim 2. 4. The string protective material according to claim 1 , wherein a pair of the notches are provided at symmetrical positions with respect to the axis of the through hole . 5. The string according to any one of claims 1 to 4, wherein the at least part of the cylindrical portion is provided with the notch in the entire length of the through hole from the base portion to the tip of the cylindrical portion. Protective layer. A tennis racket, wherein the string protecting member according to any one of claims 1 to 5 is fitted in a string groove provided in a racket frame surrounding a hitting surface . A vibration damping material having a viscoelastic material made of rubber, elastomer or resin having a lower elastic modulus than that of the string protective material in a substantially band shape is interposed between the racket frame and the band portion of the string protective material. Item 9. A tennis racket according to item 6 . The viscoelastic material has a complex elastic modulus E * of dynamic viscoelasticity at −5 ° C. measured at a frequency of 10 Hz in a range of 1.5 × 10 ^{7 to} 5.0 × 10 ⁹ dyn / cm ^2. Item 9. A tennis racket according to item 7. Alternatively the entire periphery of the ball striking face of the string protection member, the claims 6 to 8 is attached to the 3 o'clock section and 9 o'clock portion and the yoke when the 12 o'clock top position the ball striking face as watch face The tennis racket according to any one of the above items.

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