EP1154822B1 - Racket for ball games - Google Patents

Description

The invention relates to a ball game racket, especially tennis rackets, with several longitudinal strings and a plurality of perpendicular to the longitudinal strings arranged substantially vertically Cross strings, with the main strings with the cross strings Forming crossing points and at least one part the crossing points between a respective longitudinal string and a respective cross string secured against falling out, elastic intermediate members are provided.

Such a ball game racket is known from DE-OS 2654896 known. The focus of this document is the task intersecting transverse and longitudinal strings of a ballgame racquet to block at the crossing points, so that the strings can not move against each other. These described intermediate links should be made of rigid or semi-rigid Material, preferably of a plastic, such as Polyacethal or polyamide resin, but also of a metal consist. It also addresses the possibility that the Intermediate links store and return elastic energy can. The intermediate links are essentially fully cylindrical shaped and have a diameter of 3 to 4 mm. To accommodate the strings grooves are provided whose bottoms should have a distance to each other between 0 and 0.4 mm.

The tennis racket described in the document has a natural gut string, which is the preferred one Material for playing tennis acts as natural gut has an elastic elongation of 25% and over a prolonged period no material fatigue shows. Natural gut strings are very expensive, so that they significantly increase the purchase price of a tennis racket.

For this reason, tennis rackets are currently predominantly in the Insert whose strings are made of Nylon® or polyester.

To the best possible playing characteristics of a tennis racket to ensure there are a number of parameters that must be considered when selecting the clothing. Especially here is the used string material and the Thickness of the used string crucial, because of the elasticity properties the string the playing characteristics of the ready-covered racket to be determined.

Basically, there are conflicting requirements. On the one hand, elastic strings are used for soulful play needed, which is already at lower loads stretch sufficiently to give a total spring effect of the covering to enable. On the other hand, for harder punches also the strength of the covering important, because the Stringing on hard punches may not extend so far that it comes to a kind of trampoline effect, the ball direction would make it uncontrollable. Too deep immersion in the string bed also leads to absorption the forces applied by the player as well as a reduction the rebound forces.

By an elongation of the strings also allows the elasticity conventional strings very quickly after that until finally have no elasticity.

There is therefore a need for a ball game racket over has a high elasticity and beyond low shows possible material fatigue phenomena.

FR-A-721 797 describes platelets of elastic material, the elasticity of a tennis racket stringing in which the tiles at the crossing points the clothing in each case between a longitudinal and a Cross string of the covering to be inserted. The tiles are after insertion by the exerted by the fabric Pressure almost completely compressed, so that they can not act as an effective spring element. something similar applies to the elastic described in FR-A-786 619 Platelets, which may be made of rubber, for example, and at the crossroads of a tennis string made of metal are arranged.

FR-A-2208689 and DE-A-29 22 631 describe intermediate links, as the protective particles for each used Tennis string serve, whereby an influence of the Game characteristics of tennis racket stringing not desired is.

DE 43 05 829 A1 has a string for the covering of a Tennis, badminton or squash racket to the object, the from several, present as round braid, single filaments consists. Such so-called. Multifilament strings are Entwikkelt been made to match the playing characteristics of a tennis string to come as close as possible to the preferred natural gut material.

US-A-4,168,065 shows a tennis racket cover arranged at the crossing points spacer particles, the provide a concave surface shape of the clubface. Refer to the intended changes in the game characteristics focus on the simplification of, for example, top spin or side-spin punches.

The invention is therefore based on the object, a ball game rackets to create that in its playing characteristics is variable and those of a tennis racket with strings from natural intestine waiving the material natural gut as close as possible or even better.

• die Längssaiten und die Quersaiten aus einem Material bestehen, das eine elastische Längsdehnung von maximal 15% aufweist,
• die Zwischenglieder in Richtung von einer jeweiligen Quersaite zu einer jeweiligen Längssaite eine elastische Stauchung aufweisen, die bei einem Druck von 22 N/mm² mindestens 20% beträgt,
• die Zwischenglieder eine Länge von 0,5 bis 2,5 mm aufweisen, und
• die Zwischenglieder in ihrem mittleren Bereich einem Querschnitt aufweisen, der größer als der Querschnitt der Zwischenglieder an den Stirnseiten ist.

This object is achieved in the aforementioned ball game rackets in that

• the longitudinal strings and the transverse strings are made of a material having a maximum elastic elongation of 15%,
• the intermediate links in the direction of a respective transverse string to a respective longitudinal string have an elastic compression, which is at least 20% at a pressure of 22 N / mm ² ,
• the intermediate links have a length of 0.5 to 2.5 mm, and
• the intermediate links in their central region have a cross section which is larger than the cross section of the intermediate links at the end faces.

As provided for the longitudinal strings and the cross strings a material whose elastic elongation does not exceed 15% is limited, come according to the invention materials for the Strings in question, the generally lower fatigue by continuous use of the ball game racket show than hitherto usual materials for Ballspielschlägersaiten. So is the elastic strain at Nylon® strings at 28%, while the elastic elongation at Polyester strings is between about 15% and 25%. Opposite come in accordance with the invention also string materials Question that has not been considered in ball game rackets been drawn. In particular, steel strings, Aramid fibers with an elastic elongation of about 4% and Kevlar® strings are used. Preferably, the Cross strings and the longitudinal strings, however, from hochverstrecktem Polyester with an elastic elongation in the range of 8 to 12%.

The missing compared to the prior art elasticity the fabric formed by the longitudinal and transverse strings a ball game racket according to the invention of the pontics provided, whose elastic compression exceeds a predetermined minimum value, that is their elasticity must have a minimum value.

The number of intermediate links to be provided is preferred evenly distributed over the longitudinal and transverse strings, depends on the desired elasticity of the fabric. Basically, the elastic compression of the intermediate links with decreasing elastic elongation of the Increase strings. The intermediate links act like spring elements, by the impact of a ball on the fabric be compressed and then their stored return elastic energy to the ball again. Prefers are at least 20% of the crossing points with the pontics fitted. To further increase the elasticity However, the clothing can also be 50% and even 95% of the Intersection points be equipped with pontics. Around the playing characteristics of a natural gut string especially close or surpass these, the proportion of with intersections equipped intersections so high be as possible.

The intermediate links may be made of polyurethane, for example or rubber. Basically, however, each one is Material conceivable that meets the requirements of the elastic Compression met. There are also intermediate links conceivable, the consist of several components, one of which as a spring element is trained. The materials polyurethane and However, rubber is characterized by the fact that they are durable are claimable, without fatigue demonstrate. It should be noted that the intermediate links over the life of a commercial example Tennis string can only be used for about 10 minutes.

Preferably, the elastic compression of the intermediate links at a pressure of 22 N / mm ^{2 is} between 40 and 70%, particularly preferably between 50 and 60%. It has been shown that a length of a full polyurethane material cylinder of 0.8 to 1.2 mm with a diameter between 1.5 and 2 mm is particularly favorable.

To secure the intermediate links against falling out, show the front strings facing a main string or a cross string the intermediate links preferably each have a groove for Recording of the longitudinal or transverse string. The groove can be in their shape adapted to that of a standard tennis string which has a diameter of 1.0 to 1.4, preferably from 1.1 to 1.2 mm, has.

The intermediate links have one in their middle area Cross section, which is larger than the cross section of Intermediate links on the front strings is. That way the middle region of the intermediate links an increased spring force, the relevant for the elasticity of the intermediate member is.

Conventional strings have one upon impact of a ball linear force-strain curve. If a number of appropriate Intermediate links in a tennis racket stringing is inserted, results in a progressive force-strain curve and change the playing characteristics of the stringing through the extra elasticity. At the impact of a Balles on the so changed covering acts on the spring elements a momentary compressive force under which these compressed become. This is not just the case at the ball hits the strings directly, but through the interwoven strings it comes to a Distribution of load, taking at all crossing points the respective two crossing strings on each other are pressed and intermediate members are pressed together. This already causes the introduction of a smaller number (For example, 15 pieces) of the intermediate links a significant Change of game properties.

The elastic intermediate links now make it possible to to provide a racquet clothing, which meets the two conflicting requirements, both weak and heavy use to provide adequate elasticity behavior. This is made by a covering with an even relatively inelastic String achieved, with low impact by the elastic intermediate links a satisfactory Elasticity is achieved. For the soulful tennis game So these intermediate links take over most of the rebound forces, because at the low stress the relatively inelastic string not very much extended, but by the compression of the spring elements as a whole nevertheless a high elasticity is achieved. The rebound forces are by choosing the hardness of the intermediate links (for example, by the shape or the material) adjustable. The rebound forces can be applied almost without fatigue be, as a short compressive stress the material is not as much harms as a permanent tensile load and even after a long game a total of only a very short Loading time arises.

For the athletic "power game" with a lot of power, however gives the relatively inelastic string the necessary control and precision, which is too deep immersion of the ball in the Besaitungsfläche and thus an undesirable trampoline effect prevented.

This combination was previously not possible with a stringing, because these are either relatively elastic or inelastic was selected, depending on the style of play. In known strings It is noticeable that after an extremely short time (about 30 Minutes of play) the rebounds for the soulful Lost tennis game. This happens due to a Elongation of the strings under heavier loads, but also by prolonged lying of the covered rackets. This results a lack of elasticity of the strings when sentimental Game, with no sufficient spring-back forces sentimentally played balls are more present. For top players one can observe that these in a match Change your racket up to seven times to use a stringing to avoid this effect.

With the pontics according to the invention this occurs Effect not on. Here is the behavior at low forces (soulful game) by the as "compression springs" too meaningful intermediate links, which determines no fatigue subject.

Basically it is possible the number, the position and to choose the elasticity of the intermediate links individually so that an optimal adaptation to each type of game done can. Particularly advantageous is the arrangement of the intermediate links in the edge area of the racket, which makes a very good Damping of the vibrations is achieved over the Frame to be transferred to the striking arm. An attenuation These vibrations have a significant effect on education a tennis elbow caused by the vibrations opposite.

Fig. 1

eine aus dem Stand der Technik bekannte Ausführungsform eines Zwischengliedes für einen Tennisschläger;

Fig. 2

eine andere aus dem stand der Technik bekannte Ausführungsform eines Zwischengliedes für einen Tennisschläger;

Fig. 3

die Ausführungsform für ein Zwischenglied von Fig. 2 in zusammengedrücktem Zustand;

Fig. 4

einen Ausschnitt aus einer Tennisschlägerbesaitung, die mit Zwischengliedern ausgestattet ist;

Fig. 5

einen Tennisschläger, der an seinem Rand mit Zwischengliedern ausgestattet ist; und

Fig. 6

eine weitere Ausführungsform eines Zwischengliedes für einen Tennisschläger.

Embodiments of the invention will be described in more detail with reference to the drawings. Show it:

Fig. 1

a known from the prior art embodiment of an intermediate member for a tennis racket;

Fig. 2

another known from the prior art embodiment of an intermediate member for a tennis racket;

Fig. 3

the embodiment for an intermediate member of Figure 2 in a compressed state.

Fig. 4

a section of a Tennisschlägerbesaitung, which is equipped with pontics;

Fig. 5

a tennis racket equipped with pontics at its edge; and

Fig. 6

Another embodiment of an intermediate member for a tennis racket.

In Figure 1, an intermediate member 1 for a string crossing the stringing of a tennis racket made of hochverstrecktem Polyester with an elastic elongation of 10%. Between crossing strings (not shown) is the intermediate member 1, made of polyurethane material is made. The two ends 2, 3 of the intermediate member 1 are formed as groove-shaped brackets that each other are arranged at a 90 ° angle and crossing each other Partially surround strings. Between these two Mounts a block 4 is arranged polyurethane material. This block 4 is referred to herein as a "spring element", because he is mainly for the cushioning of the strings caused against each other at a compressive stress by the elongation of the strings, is responsible. However, since the entire intermediate member in one piece from the resilient polyurethane material is made, finds part of the suspension also in the area of brackets.

In the known embodiment of an intermediate member shown in Fig. 1 is the Spring element designed as a cube of approx. 1-2 mm edge length. The brackets are elongated half shells, the two sides protrude beyond the spring element.

In Fig. 2 is an alternative embodiment of an intermediate member 5 shown from the prior art. Here is the spring element as Cuboid of about 1.5 mm in length and a base of approx. 1.2 x 1.2 mm executed. The attached to the strings cup-shaped Brackets close flush with the spring element from.

FIG. 3 shows the intermediate member 5 from FIG. 2, whereby by impact the two strings on each other are pressed. This can happen on the one hand that the string crossing is hit directly by the ball and so on the superimposed strings are pressed together. By alternately over and interwoven Arrangement of Besaitung (see Fig. 4) spreads a such compressive stress over the entire surface of the clothing, so that even at such string crossings compressive forces arising from the point of impact of the ball lie.

As shown in Figure 3, the spring element under the Compressive stress elastically compressed. hereby it comes to the storage of energy in the spring element, which is released again during the subsequent spring-back. While this case at the individual intersection point only one very low travel is achieved (the total height of the Intermediate member is depending on the embodiment about 0.5 to 2.5 mm) results for the playing characteristics of the fabric important overall spring force from the addition of the Spring forces of the individual intermediate elements. Depending on the number the longitudinal transverse strings and the resulting crossing points the strings of a racket is the number the possible intermediate elements 300 to 400 pieces.

In the embodiment, the fabric is formed from a relatively inelastic, otherwise unusable string, For example, a steel side or a plastic string made of highly stretched polyester (polyethylene terephthalate). After attaching the fabric with a relatively low tensile force become the intermediate links 5 already described some string crossings inserted into the fabric. hereby results in a greater clamping force, because the intermediate links have a longitudinal extent of 0.5 to 2.5 mm. By the subsequent introduction of these intermediate links at some (eg 20) string crossings the Hardness of the clothing subsequently increased. coverings, already some of their elasticity by extension may have lost the strings under stress, so by subsequent insertion of the intermediate links again get an increased stringing hardness and already lost Regain elasticity.

The so-strapped and pinned racket now shows in both high stress areas (i.e. hard strokes) as well as emotional play (eg Lobs and stops) very good gameplay. With soulful Game, i. low stresses will be the necessary Elasticity mainly by the compression of the spring elements the intermediate links applied. The relatively inelastic String lengthens under such conditions only very little. By distributed as described above Stress of all intermediate links in the fabric results However, a total of very high elasticity, the supportive feeling game.

At high loads, i. hard blows are the Spring elements also compressed. Because of the very However, the load also expands the used String material now elastic, making it a total of one sufficiently elastic playing behavior comes. Due to the high strength of the string used is too high "Trampoline effect" in which the ball is too deep in the stringing dips and thus becomes uncontrollable, avoided. The intermediate links are here, as shown in Fig. 3, Although maximally compressed. This results however, due to the prevailing compressive stress no Damage to the material, i. after the blow, the spring elements completely elastic again to the old size spring back.

In the arrangement of the intermediate links in the tennis racket stringing It is suggested that these are mainly in the area of to arrange so-called "sweet spot". This is the area in which ideally the ball meets the bat. The Effect of the pontics is most pronounced when they are concentrated in this area.

Claims (7)

1. Racket for ball games, in particular a tennis racket, with several longitudinal strings and several transverse strings, which are essentially arranged vertically to the longitudinal strings, said longitudinal strings forming points of intersection with the transverse strings, and elastic intermediate elements, which are secured against falling out, being provided between a respective longitudinal string and a respective transverse string for at least part of the points of intersection,
   characterised in that

   the longitudinal strings and the transverse strings consist of a material which has a maximum elastic lengthening strain of 15%,

   the intermediate elements (1; 5; 7) in the direction of a respective transverse string to a respective longitudinal string have an elastic compression, which is at least 20% at a pressure of 22 N/mm²,

   the intermediate elements (1; 5; 7) have an overall height of 0.5 to 2.5 mm and

   the intermediate elements (7) have in their central area a cross section greater than the cross section of the intermediate elements (7) on the front ends.
2. Racket for ball games according to claim 1, characterised in that the transverse strings and the longitudinal strings consist of highly drawn polyester with an elastic lengthening in the range of 8 to 12 %.
3. Racket for ball games according to one of the claims 1-2, characterised in that at least 20%, preferably at least 50% and in particular at least 95%, of the points of intersection are fitted with the intermediate elements (1; 5; 7).
4. Racket for ball games according to one of the claims 1-3, characterised in that the intermediate elements (1; 5; 7) consist of polyurethane or caoutchouc.
5. Racket for ball games according to one of the claims 1-4, characterised in that the elastic compression of the intermediate elements (1; 5; 7) lies between 40 and 70% at a pressure of 22 N/mm².
6. Racket for ball games according to claim 5, characterised in that the elastic compression of the intermediate elements (1; 5; 7) lies between 50 and 60% at a pressure of 22 N/mm².
7. Racket for ball games according to one of the claims 1 to 6, characterised in that the front ends of the intermediate elements (1; 5) facing a longitudinal string or a transverse string, respectively, have a groove for the accommodation of the longitudinal or the transverse string.

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