EP0163710B1 - Tennis racket frame - Google Patents

Abstract

The frame of a tennis racket is comprised of a U-shaped hollow section (1, 1a), made according to an injection moulding process, open outwardly in the frame plane, which is formed of a linking bridge (4) and lateral branches (31, 32) and which is rigidly nested into and covered by a counter-section (30). Between the two sections (1, 1a; 30), reinforcement ribs (15, 49, 50, 51) and the holes (8) for the support sleeves (10) receiving the strings are connected to one of the two sections (1, 1a; 30) so as to form a single piece, the reinforcement ribs (15, 49) being attached to the support sleeves (10). In order to obtain a racket having an excellent rigidity to distorsion and which is very easy to play, reinforcement ribs (15, 49, 50, 51) are attached to the support sleeves (10) and are connected both to the linking bridge (4) of the U-shaped hollow section (1, 1a) and to the lateral branches (31, 32) of said hollow section (1, 1a).

Description

The invention relates to a tennis racket, consisting of an injection-molded, open to the outside U-shaped profiled hollow profile, which consists of a connecting web in which the holes for the implementation of the strings are arranged, to which lateral U-legs connect , which define an interior, which is positively covered by a counter profile, in which holes are also arranged for the passage of the strings, which are aligned with the holes in the hollow profile, reinforcing ribs being arranged in the interior of the hollow profile.

A tennis racket mentioned at the outset has become known, for example, with the subject of US Pat. No. 4,194,738. The U-shaped profiled hollow profile shown there has no reinforcing ribs in the interior. Rather, the reinforcing ribs are formed on the central web of the counter profile inserted into the hollow profile and are supported on the base of the connecting web of the U-shaped profiled hollow profile. The purpose of this measure is to force the stringing force from the strings onto the hollow profile. A disadvantage of this, however, is that the reinforcing rib is formed as a central, circumferential rib on the counter profile, which means that the racket head is only slightly resistant to torsion, because a central, continuous rib, which lies loosely on the inside of the connecting web of the hollow profile, a relative allows severe twisting of the club head. Another disadvantage is that only low bending stiffness and poor damping capacity are achieved.

In addition, there is an unfavorable weight distribution of the known tennis racket because it is very top-heavy. The U-shaped profiled hollow profile is namely equally strong in the entire head area, which leads to the fact that the tip of the tennis racket is particularly heavy, which leads to the described top heaviness and thus to difficult playability.

The U-shaped hollow profile in the club head area converges in the grip area to form a double-T profile. From an injection molding point of view, such a double-T profile can only be mastered with appropriate side shifters, which leads to increased production costs and thus to higher costs of this tennis racket. In addition, there is the disadvantage that only one and the same grip thickness can be produced in the mold; there is therefore no possibility of using interchangeable inserts with which different grip thicknesses could be produced. Different grip strengths can therefore only be achieved with this known tennis racket by foaming a polygonal grip profile onto the double-T profile, which in turn is surrounded by a corresponding masking tape. This has the disadvantage that the handle consists of several different materials, which may have connection problems.

With FR-A-2 270 908 a further tennis racket frame, made by injection molding, has become known, which is composed of two half-shells which, when placed on top of one another, overlap and are connected to one another. However, the profile of this tennis racket does not consist of a hollow profile which is open to the outside and has the disadvantages of poor flexural rigidity, torsional rigidity and poor damping behavior.

The object of the invention is to develop a tennis racket according to US Pat. No. 4,194,738 in such a way that it has improved mechanical properties at comparable or lower production costs, particularly with regard to the torsional rigidity, the flexural rigidity and the damping behavior.

To achieve the object, the invention proposes a framework with the features of claim 1.

An essential feature of the invention is therefore that the reinforcing ribs are arranged in the U-profile itself, which are also connected in one piece with the U-profile molded support sleeves, in which the holes for the strings are made. The stringing is therefore no longer - as in US-A-4 194 738 - transmitted to the U-profile via the counter-profile and a reinforcing rib connected to the counter-profile, but the U-profile itself now serves directly to take the load in the direction of the covering. The improved bending stiffness and torsional stiffness is achieved by the aforementioned reinforcing ribs, which are integrally connected to the support sleeves. Support sleeves and reinforcing ribs are thus load-transferring elements in the U-shaped hollow profile.

A particularly favorable distribution of the reinforcing ribs results from the fact that the reinforcing ribs extend in a star shape from the support sleeves and are connected both to the connecting web and to the U-legs.

Outstanding static and dynamic properties can be achieved with a tennis racket designed according to the invention. In particular with regard to the transmission of force to the ball, the inherent damping (reverberation behavior), the torsional elasticity (torsional stiffness) and the fatigue strength with strings, properties are achieved that have previously only been achieved with much more complex, plastic Laminations process to produce rackets, which are reinforced in places by graphite inlays. In this known method, a tube is wrapped with resin-impregnated glass fiber rows, graphite inserts and other insert parts being introduced during the winding process. The rowing produced in this way is placed in a closed press mold, whereupon the tube is inflated so that the synthetic resin layer attaches to the heated press mold and hardens. 60% of the production costs of such a known racket are reworking costs, which are incurred by grinding, deburring, filling, painting and drilling the string feedthroughs. Such a known racket with excellent playing properties costs about 3 to 4 times the manufacturing costs that must be used in a racket according to the present invention. It has been shown that a racket according to the present invention has equally good static and dynamic properties (based on the parameters mentioned above), but is much cheaper to manufacture.

According to the subject matter of claim 6, it is preferred in this case if the reinforcing ribs and the support sleeves extend up to close to the end faces of the U-legs of the hollow profile, the counter profile being inserted into the interior of the hollow profile defined thereby, which has a tapering side Profile legs covering the end faces of the U-legs. This results in an optically closed impression of the club head, it being possible to design the counter profile in a different color than the U profile. By inserting the counter profile into the interior of the U profile, the string knots are optimally protected. A soft transition at the edges is achieved by the tapered profile legs lying on the end faces of the U-legs, whereby the edges of the hollow profile itself are still protected against damage.

For high strength requirements, it can be provided according to the subject matter of claim 7 that the counter profile is integrally connected to the U-legs of the hollow profile in the region of the tapered profile legs. Such a material connection could take place by ultrasonic welding or by vibration welding. Gluing is also possible.

A complete protection of the string knots results from the subject of claim 8 in that the counter profile has a circumferential locking groove, which is delimited by opposite, lateral locking lips, behind which an elastically deformable protective profile can be pressed into the locking groove, which covers the string knots . As a result, the entire narrow side of the club head is protected against damage and the visual impression is optimal, because the knots are no longer visible.

It is preferred if the bending moment of resistance of the hollow profile in the head area of the racket is reduced compared to the bending moment of resistance in the other areas. The tip of the racket head thus has a U-profile of smaller width and lower leg height than comparatively the rest of the U-profile in the other areas of the racket head. By coordinating the dimensions of the U-profile on the racket tip in comparison to the other areas, you can therefore set the tennis racket top-heavy or handle-heavy.

Experience has shown that the greatest bending and torsional loads act on the heart area of the racket. It is therefore preferred according to the subject matter of claim 9 if in the heart region of the racket two U-profiles with reinforcing ribs molded therein are integrally formed on the circumferential hollow profile defining the club head, the U-profiles converging in the handle of the racket and integrally there connect the edge profile of the handle. The corresponding one-piece connection is made in the casting mold with the help of sliders moving to the side, which is easy to master by injection molding or casting.

It is essential here that the handle of the racket consists of a polygonal, approximately rounded profile edge profile, which has a central bore. The longitudinal axis of the bore is aligned parallel to the longitudinal axis of the racket, so that the handle can be formed directly in the injection mold by a slide which moves in at the end and which enters the central bore. This results in an optimal connection to the two U-profiles of the centerpiece and a heavy-duty connection. Another advantage is that the diameter of the edge profile can be changed directly by replaceable inserts in the injection mold, so that it is possible to produce the racket with a certain grip strength in one step in the mold. It is then no longer necessary to foam up a further grip piece or to take other measures in order to obtain a desired grip strength.

According to the invention, only the hollow profile is produced by injection molding. The counter profile and the cover profile can be produced by extrusion. It is also essential that the material used for the hollow profile produced by the injection molding process is a high-strength, thermoplastic, to which carbon fibers in the range from 20 to 40% by weight are added. In addition to the addition of carbon fibers, glass fibers can also be added. B. a Share of 20% glass fibers and 20% carbon fibers can be used. These mixing ratios can be varied within a wide range and depend on the desired final strength and the required manufacturing costs. In the injection mold inserts, the z. B. additionally strengthen the heart area, be inserted.

The subject matter of the present invention results not only from the subject matter of the individual patent claims, but also from the combination of the individual patent claims with one another.

All of the information and features disclosed in the documents, in particular the spatial design shown in the drawings, are claimed to be essential to the invention, insofar as they are new to the prior art, individually or in combination.

In the following, the invention is explained in more detail with reference to drawings showing several possible embodiments. Further features and advantages of the invention which are essential to the invention emerge from the drawings and their description.

• Figur 1: Horizontal-Teilschnitt durch einen Tennisschläger nach der Erfindung in Höhe der Schnittlinie I-I in Figur 2,
• Figur 2: Seitenansicht des U-förmig profilierten Hohlprofils in Richtung des Pfeiles 11 in Figur 1,
• Figur 3: Schnitt gemäss der Linie III-III (Fig. 2) durch das Hohlprofil mit eingesetztem Gegenprofil und Schutzprofil,
• Figur 4: eine Variante zur Ausführung des Gegenprofils,
• Figur 5: schematisiert gezeichnete, verschiedene Querschnittsgebungen für das U-Profil,
• Figur 6: schematisiert eine Querschnittsform, bei der Stützhülsen einstückig mit dem Hohlprofil verbunden sind,
• Figur 7: eine zweite Variante zur Ausbildung der Verstärkungsrippen in einer Ansicht ähnlich wie in Figur 2,
• Figur 8: dritte Variante der Ausbildung der Verstärkungsrippen,
• Figur 9: vierte Variante zur Ausbildung von Verstärkungsrippen.

Das in den Figuren 1 bis 3 gezeigte Hohlprofil 1a besteht aus einem U-Profil 2a, welches gemäss Figur 3 eine dachkant-förmige Profilgebung aufweist.Show it:

• FIG. 1: horizontal partial section through a tennis racket according to the invention at the section line II in FIG. 2,
• FIG. 2: side view of the U-shaped profiled hollow profile in the direction of arrow 11 in FIG. 1,
• Figure 3: Section along the line III-III (Fig. 2) through the hollow profile with inserted counter profile and protective profile,
• FIG. 4: a variant for the execution of the counter profile,
• FIG. 5: schematically drawn, different cross-sectional conditions for the U-profile,
• FIG. 6: schematically shows a cross-sectional shape in which support sleeves are connected in one piece to the hollow profile,
• FIG. 7: a second variant for forming the reinforcing ribs in a view similar to that in FIG. 2,
• FIG. 8: third variant of the design of the reinforcing ribs,
• Figure 9: fourth variant for the formation of reinforcing ribs.

The hollow profile 1a shown in FIGS. 1 to 3 consists of a U-profile 2a, which according to FIG. 3 has a roof-shaped profile.

A central web part 25 lying horizontally in FIG. 3 is adjoined at an angle to the horizontal by two web parts 26, 27 which merge into vertical U-legs 31, 32.

According to FIG. 1, reinforcing ribs 15 are built into the U-profile, which are integral with the material of the U-profile 2a. Figure 1 and Figure 3 show that 25 support sleeves 10 are formed on the inside of the central web part, to which the reinforcing ribs 15 (Fig. 2) connect laterally and in a star shape. The support sleeves 10 are connected in the direction of the longitudinal axis (section line II in FIG. 2) by the central ribs 28, while the spread apart side ribs 29, which meet in the region of the inner wall of the U-legs 31, 32 and there with the U-legs 31, 32 are connected in one piece.

The resulting spaces between the reinforcing ribs 28, 29 are filled in the injection mold by sliders.

FIG. 1 shows the horizontal section through the central rib 28, the (cut) support sleeves 10 forming bores 8 for the passage of the strings. The diameter of the bores 8 is chosen so that it is smaller than the web width of the web part 25 (see FIG. 3).

The club head is formed by the all-round, self-contained U-profile 2a. In the connection area 41, two U-profiles 39, 40 are formed in one piece from the surrounding U-profile 2a. This forms the heart region 38, in the center of which a V-shaped recess 48 is formed. The two U-profiles 39, 40 also have internal reinforcing ribs 15 in the manner described with reference to FIGS. 2 and 3. However, the support sleeves 10 shown in FIG. 2 with the bores 8 made therein are missing.

The two U-profiles 39, 40 converge in a connection area 42 on the handle 43 and are connected there in one piece to the edge profile 48 of the handle 43. The edge profile is a hexagonal to ten-sided profile approximated to the round profile, this edge profile 46 being shaped in the injection molding machine by means of a slide which moves into the central bore 44 in the direction of the arrow 45.

In Figures 1 and 5 it is indicated schematically that the section modulus 11 of the hollow profile 1a at the tip of the racket head is lower than the section modulus 12 of the hollow profile 1a in the remaining area. The transition here is continuous, with symmetrical U-profiles with different leg lengths 13 and web width 14 being used with respect to the axis of symmetry 16 (FIG. 5).

The reinforcing ribs 15, which form the support sleeve 10 with the bore 8 introduced therein, extend close to the end faces of the lateral U-legs 31, 32 (FIG. 3). A counter profile 30 is inserted into the interior space 18 of the hollow profile 1a defined in this way, which covers the end faces of the U-legs 31, 32 with lateral, tapering profile legs 33. The profile legs 33 have a radius 47 on the surface, with which they run into two opposing, facing locking lips 35, which have a locking groove 34 between them for receiving a protective profile 36 train. The protective profile 36 here consists of an elastic band which can be clipped into the locking groove 34 behind the locking lips 35. As a result, the string knots 37 are optimally protected and are no longer visible from the outside.

Bores 5 (not shown in FIG. 3) are made in the counter profile 30, which are aligned with the bores 8 in the U profile 2a.

4 to 9 show simplified modifications of the preferred exemplary embodiment shown in FIGS. 1 to 3.

The hollow profile 1 shown in FIG. 6 is in turn a U-profile 2, in which the counter profile 3 can be designed differently according to the representations in FIGS. 4, 6 to 9.

In the embodiment in FIG. 6, the connecting web 4 of the U-profile 2 has support sleeves 10 formed integrally with this connecting web 4. The support sleeves 10 have such a clear diameter that the bores 5, which can be integral with the counter-profile 3, but not need to be introduced. In such designs, injection technology always ensures that the bores 5 for the string feed-throughs are kept clear of every burr and always ensure optimal and rapid threading of the strings.

In the counter profile 3, recesses 23 are then provided, which serve to accommodate the strings, so that the strings are embedded on the outer circumference of the racket in a manner protected against mechanical damage.

Figure 4 shows that the counter profile can also be formed from a band 20 on which the guide sleeves 7 are integrally formed with the holes 5 made therein.

The comparison between Figures 3 and 6 shows that the U-profile can be formed at an angle of 90 ° with a straight connecting web 4, while according to Figures 1 to 3, the connecting web 4a is roof-shaped. As a result, the air resistance of the racket is lower in the plane perpendicular to the stringing plane and the ball does not jump off uncontrollably when it hits the outside of the hollow profile 1a.

Overall, the invention shows that it is possible to design a racket made by injection molding in such a way that it is equivalent in terms of its static and dynamic properties to rackets, the production of which causes a multiple of the costs that are spent on the racket according to the invention .

For reasons of cost, it is preferred here if the material thicknesses of the reinforcing ribs 15 of the connecting webs 4 and the U-legs 31, 32 are chosen to be the same.

With reference to FIGS. 7 to 9, further design variants are mentioned with regard to the design according to FIG. The same reference numbers apply to the same parts, it being essential that reinforcing ribs 49, which have a cruciform shape, are formed in the U-profile 2a shown in FIG. The U-legs 31, 32 of the U-profile 2a are connected to one another via reinforcing ribs running in the transverse direction, while the support sleeves 10 are connected to each other via reinforcing ribs running in the longitudinal direction. This results in a grid or grid-shaped arrangement of the reinforcing ribs 49.

In FIG. 8, an X-shaped arrangement of the reinforcing ribs 50 is provided, while in FIG. 2, a zigzag-shaped arrangement of the reinforcing ribs 51 is provided.

These design variants can therefore directly replace the exemplary embodiment according to FIG. 2.

Claims (11)

1. Frame for a tennis racket, characterized by

(a) an injection molded U-shaped and in the plane of the frame towards the outside open profiled frame member (1, la) consisting in section of two laterally legs (31, 32) with a connecting land (4, 4a) between them:

(b) a counter profiled frame member (30) which is positive covering the open side of the frame member (1, 1a);

(c) supporting sleeves for receiving the strings, and which being one-piece joined to the connecting land (4,4a);

(d) each supporting sleeve comprising at least two reinforcing ribs (15, 49, 50, 51) one-piece joined to the connecting land (4, 4a) whereat one of the reinforcing ribs is one-piece joined to one of the laterally legs of the U-shaped member and the other one of the reinforcing ribs to the second leg.

2. Frame for a tennis racket according to Claim 1,
characterized in that the reinforcing ribs (15) extend star-shaped radially from the supporting sleeves (10) towards the laterally legs (31, 32) and that supporting sleeves (10) are connected with each other by an additional central rib (29).

3. Frame for a tennis racket according to Claim 1.


characterized in that the reinforcing ribs (49) are provided extending star-shaped from the supporting sleeves (10) whereat one reinforcing rib is connecting the supporting sleeves (10) with each other and the other reinforcing ribs extending towards the laterally legs (31, 32).

4 Frame for a tennis racket according to Claim 1,
characterized in that the reinforcing ribs (30) are extending in pairs X-shaped arranged from the supporting sleeves (10) towards the laterally legs (31, 32).

5. Frame for a tennis racket according to Claim 1.
characterized in that the reinforcing ribs (51) extend zig-zag shaped between the supporting sleeves (10).

6. Tennis racket according to one of Claims 1 through 5,
characterized in that the supporting ribs (15, 28, 29, 49-51 ) extend up to near the ends of the U-shaped legs (31, 32) and the counter-profiled member (30) respectively, that in the inner space (18) of the profiled frame member (1, 1a) defined by this, the counter-profiled member (30) is inlaying with its acutely conical and tapered laterally ends (33) covers the end faces of the U-shaped legs (31, 32).

7. Tennis racket according to Claim 4,
characterized in that the counter-profiled member (30) is positively attached frame member (1 a) by means of welding or cementing in the region of the acutely conical formed profiled legs (33).

8. Tennis racket according to Claim 7,
characterized in that the counter-profiled member (30) comprise a catch groove (34) which is confined by opposing arranged laterally catch lips (35), behind which an elastically workable protection profile (36) can be receivingly in, which covers the string knots (37).

9. Tennis racket according to Claim 1,
characterized in that in the heart region (38) of the racket two U-shaped members (30, 40) with thereto one-piece formed reinforcing ribs (15,49-51) are attached to the hollow profiled frame member (1, 1a), and that the U-shaped members (39, 40) converge in the handle (43) of the racket and in that region connect to the edge profile (46) of the handle (43).

10. Tennis racket according to Claim 9,
characterized in that the handle (43) of the racket consists of a multi-edged, a round profile like edge profile (46) which is having a central bore (44).

11. Frame for a tennis racket according to Claim 1,
characterized in that the counter-profiled member is formed by a band (20) to which joined are guiding sleeves (7) with therein arranged bores (5).

Images