EP1557204B1 - Racquet for ball sports and method for manufacturing - Google Patents

Abstract

Racket (2) comprises a racket head (6) and a frame (4) with a connected grip section (10). The racket head defines a tensioned surface and the frame profile has four trough-shaped indentations (12) lying opposite each other and arranged symmetrical to the longitudinal axis of the racket.

Description

The present invention relates to a racket for ball games, in particular a tennis, squash, badminton, racquetball or paddle tennis racket with excellent handling characteristics, as well as a manufacturing method for such a racket.

Such clubs typically include a frame that forms a club head and a handle portion connected thereto. Typically, a so-called heart region is formed in the transition region between the club head and the grip section. Typically, the frame is formed from a frame profile that is often made from a carbon fiber reinforced plastic material in a molding press. The club head of the racket defines a clothing plane in which the clothing of the racket is placed. To accommodate the sides of the clothing lying on the frame in the stringing plane through holes are provided for the implementation of clothing pages.

Moreover, it is known to provide at different points of the frame from each other different cross-sectional shapes of the frame profile, for example, to be able to provide relatively light clubs. From other points of view, it may be advantageous to provide frame profiles with varying cross-sectional shapes along the frame.

For example, the EP 0 676 222 B1 a racket having a handle and a frame having a head portion, force amplifying portions and flexible portions alternately formed along the entire frame or along a portion of the frame spaced from the handle. Each force amplifying portion is formed by a projecting frame portion having a relatively large side thickness measured in a direction perpendicular to the plane of the frame. Each of the flexible portions is formed by a recessed frame portion having a relatively small side thickness measured in a direction perpendicular to the plane of the frame. The number of 10 to 20 and the number of recessed flexible sections is also 10 to 20. This racket design to eliminate the insufficient acceleration capacity of a racket with conventional design of the classic type and the insufficient flexibility of a conventional "wide-body" racket.

The DE 37 16 708 A1 discloses a racquet having a head portion connected to a handle stem via a neck portion. The neck portion has a plurality of recesses on each of its upper and lower surfaces extending substantially parallel to the face of the head portion. These recesses are symmetrical and equidistant from each other.

The US-A-4,353,551 discloses a tennis racket with dynamically mounted mass parts which are arranged symmetrically to the longitudinal axis of the racket between a neck portion and a transverse axis of the club head. According to one embodiment, recesses are provided in the racket frame for receiving the mass parts.

The US-A-5,100,136 discloses a tennis racket with an oval club head and a club grip extending from a neck portion. An elongate, inserted channel is formed along the centerline of the outside of the head frame. In this channel a plurality of through holes are provided, can be passed through the strings of a string. On the head frame, an elongate passage opening is provided on both sides, which is spaced by a predetermined distance from the outside of the head frame for covering and extending through a base portion of the channel. Each passage opening thereby defines a pair of elongated ribs which are arranged parallel to the clothing surface and on both sides thereof. In each of the through holes, an elongated elastic member having a generally T-shaped cross section is provided.

The US-A-2002/0058557 discloses a tennis racket with a dynamic damper having a viscoelastic part and a mass part laminated thereto. The dynamic damper has horizontal frames and vertical frames so that the damper has a U-shaped cross-section. The horizontal frames are attached to the racket in its thickness direction, that is, in a direction perpendicular to the stringing plane, and the vertical frames in the width direction of the racket, that is, substantially parallel to the stringing plane of the racket. These viscoelastic dampers are preferably mounted in the region of 3 o'clock or 9 o'clock on the club head.

The present invention has for its object to provide an improved racket, which allows excellent ball guidance and acceleration and can be constructed at the same time in lightweight construction. This object is achieved with a racket having the features of independent claim 1. In the dependent claims preferred embodiments of the racket according to the invention are described. The independent method claim 11 relates to a manufacturing method for such a racket. The dependent claims relate to advantageous embodiments of the method according to the invention.

The racquet for ball games according to the invention has a frame formed from a frame or hollow profile, which has a club head and a preferably connected thereto via a heart region grip portion. The clubhead defines a stringing plane. The frame profile has four trough-shaped indentations, which are each arranged in pairs opposite and symmetrical to the longitudinal axis of the racket. In the region of the trough-shaped indentations, at least one opening extending through the frame profile is provided which runs essentially perpendicular to the clothing plane.

The trough-shaped recesses are preferably arranged on the frame profile such that a cross-sectional constriction or constriction results in a direction perpendicular to the clothing plane of the racket.

The head shape of the racket is largely arbitrary and can, for example, oval. ovate, drop-shaped, rectangular with rounded corners. To define the respective position of the trough-shaped indentations along the circumference of the club head, a dial of a watch is usually used, the 12 o'clock position being located at the outermost or free end of the club head (cf. FIG. 1 ). Accordingly, the 3 o'clock or 9 o'clock position is approximately in the middle of the total length of the club head.

The four trough-shaped indentations are arranged on the club head such that a first pair is provided between 2 o'clock and 4 o'clock, in particular at about 3 o'clock, and a second pair between 8 o'clock and 10 o'clock, in particular at about 9 o'clock. The trough-shaped indentations are accordingly spaced approximately as far from the handle end of the racket as the center of the club face or the area of the club face with maximum impact speed. Under certain circumstances, this preferred position for the trough-shaped indentations also about 1 cm to 4 cm, preferably 2 cm to 3 cm, be moved from the center in the direction of the free end of the club head.

The racket according to the invention thus has per racket side (front or back) on two trough-shaped indentations, one of which is located on this side and the other beyond the longitudinal axis of the racket. In other words, each racket side and racket half each have a single trough-shaped indentation - thus a total of exactly four indentations - provided on the racket according to the invention. Preferably, the recesses are arranged in the area at about 3 o'clock or 9 o'clock. According to the invention, a pair of trough-shaped indentations in the range between 2 o'clock and 4 o'clock, in particular at about 3 o'clock, and another pair of trough-shaped indentations between 8 o'clock and 10 o'clock, in particular at about 9 o'clock, are thus provided, ie the trough-shaped indentations arranged in pairs opposite and symmetrical to the longitudinal axis of the racket.

The cross-sectional constriction caused by the trough-shaped recesses arranged opposite the frame profile is preferably such that the frame height (in the direction perpendicular to the clothing plane) is about 60 to 95%, more preferably 70 to 90%, and even more preferably about 80% of the height of Frame profile outside the indentations amounts. The length of the recess along the frame is preferably in the range between 10 mm and 30 mm, more preferably between 12 mm and 25 mm, most preferably between 15 mm and 23 mm. The trough-shaped recesses preferably have a substantially circular arc-shaped cross section, viewed in the clothing plane, which has, for example, a radius of approximately 15 mm to 25 mm, more preferably approximately 20 mm. The cross section may also be elliptical, hyperbolic, polygonal or rectangular with rounded corners.

The racket according to the invention is particularly advantageous in terms of its improved ball guidance. In addition, vibrations that occur when hitting the ball, derived less to the handle than in known rackets. At the same time, however, the acceleration capacity that can be transferred to the ball with the racket according to the invention is improved. The advantageous properties of the racket according to the invention are probably due to the fact that the bending resistance of the frame profile is locally reduced by the trough-shaped indentations, so that a kind of "joint" ("control point") is created by these indentations.

As already mentioned above, the effect according to the invention is particularly advantageous, inter alia, if a pair of trough-shaped indentations in the range between 2 o'clock and 4 o'clock, in particular at about 3 o'clock, and another pair of trough-shaped indentations between 8 o'clock and 10 o'clock, in particular at about 9 o'clock, is provided, wherein the trough-shaped recesses are arranged opposite and symmetrical to the longitudinal axis of the racket. The Indentations at about 3 o'clock and 9 o'clock are where the ball is hit very often when playing (based on the clubface), so that the club virtually "encloses" the ball due to the local reduction of the bending resistance moment of the frame profile effected in the area of the indentations. , This has in particular a longer residence time of the ball on the fabric of the racket and thus an improved ball control result.

The effect of the invention is further enhanced by the openings. The opening extends through the pairs of oppositely arranged trough-shaped indentations. In symmetrical arrangements of two openings thus each trough-shaped indentation has a hole, so that in this area the outermost wall of the frame profile, i. the part of the wall of the frame profile which is furthest from the clothing plane, is substantially weakened, whereby the bending resistance moment of the frame profile is further reduced.

Such a weakening of the frame profile has hitherto been considered unrealisable, since it was assumed that this would inevitably result in the frame breaking at the loads occurring during play. However, it has been shown that not only a particularly good ball guidance is possible by the indentations and possibly openings, but at the same time the required stability of the racket remains guaranteed.

The trough-shaped recesses are preferably formed during the shaping of the racket in the molding press. The openings are preferably formed after forming the racket in the molding press subsequently to the frame. However, they may also be made during the molding process by, for example, inserting a core into the mold. The subsequent training is preferably carried out by drilling, milling or sawing.

The cross section of the opening is usually circular in the case of drilling, but may also have any other shape. A circular opening preferably has a diameter in the range between 2 mm and 8 mm, more preferably between 3 mm and 6 mm. In an opening formed by milling or sawing usually the two opposite holes are generated in the frame profile independently of each other, each of the holes is preferably formed in the direction of view parallel to the fabric plane substantially arcuate or trough-shaped. However, any other shape for the holes is possible. The length of each of the holes along the frame is preferably in the range between 1 mm and 10 mm, more preferably between about 3 mm and 7 mm. The depth of each hole is at least the wall thickness of the frame profile.

The width of the holes, i. their dimension in the direction of the side passage holes or perpendicular to the direction of the frame at the relevant location, is preferably in the range between 3 mm and 7 mm. The dimensions of the hole, in particular its width and depth, should be selected so that the hole does not extend to a provided in the frame groove for receiving a headband.

Analogous to the trough-shaped indentations, the openings are preferably provided in pairs substantially symmetrically to the longitudinal axis of the racket, ie, it may be two, four, six or more openings provided symmetrically to the longitudinal axis of the racket. The at least one opening is preferably in the range between 2 o'clock and 4 o'clock and / or between 8 o'clock and 10 o'clock at the club head. Particularly preferred is the paired arrangement of openings in this area. More preferably, at least one pair of apertures are provided at about 3 o'clock and 9 o'clock respectively at the club head. Further, it may be advantageous to provide a plurality of openings on each side, for example, a plurality of openings symmetrically at the 3 o'clock or 9 o'clock position or from 3 o'clock or 9 o'clock to the handle portion or starting from 3 o'clock or 9 o'clock be arranged towards the free end of the club head. Preferably, one through opening is provided centrally or centrally through a pair of opposing trough-shaped indentations.

In order to prevent the penetration of dirt and / or moisture into the frame profile, it is preferred to equip the opening with an insert, so that the frame profile is closed inwards. Preferably, the insert is tubular with a through hole formed; However, it can also be provided as a full element. The insert is usually made of an elastic material (e.g., rubber) so that the beneficial effects obtained by providing the apertures are minimally affected. It is also possible to cover each of the holes forming the opening with a separate cover made of an elastic material, whereby the same effect is achieved.

Furthermore, it may be preferable to reinforce the frame profile in the region of the recesses and the openings by the provision of reinforcing layers. In particular, reinforcing layers of carbon fiber, glass or aramid fabric and / or a unidirectional prepreg are suitable, which are arranged at an angle of ± 45 ° to the longitudinal extent of the frame profile (i.e., helically in the wall of the frame profile).

Fig. 1

eine schematische Vorderansicht eines erfindungsgemäßen Schläger, in der ein Ziffernblatt zur Angabe der jeweiligen Rahmenpositionen eingezeichnet ist;

Fig. 2a

eine vergrößerte Darstellung in perspektivischer Ansicht eines Bereichs des Rahmens eines erfindungsgemäßen Schlägers mit muldenförmiger Einbuchtung, wobei die Öffnung nicht gezeigt ist ;

Fig. 2b

eine vergrößerte Darstellung in perspektivischer Ansicht eines Bereichs des Rahmens eines erfindungsgemäßen Schlägers mit muldenförmiger Einbuchtung und der Öffnung;

Fig. 3

eine schematische Seitenansicht (Ansicht in der Bespannungsebene) auf den Rahmen eines erfindungsgemäßen Schlägers im Bereich der muldenförmigen Einbuchtungen;

Fig. 4

eine schematische Querschnittsansicht des Rahmenprofils eines erfindungsgemäßen Schlägers gemäß der in Figur 2 dargestellten Ausführungsform;

Fig. 5

eine perspektivische Schnittansicht des Rahmenprofils eines erfindungsgemäßen Schlägers mit muldenförmigen Einbuchtungen und der Öffnung;

Fig. 6a und 6b

Diagramme, in denen die relativen Geschwindigkeitswerte über der Rahmenposition für einen erfindungsgemäßen Schläger und für herkömmliche Schläger dargestellt sind; und

Fig. 7a und 7b

Diagramme, in denen die Kontaktzeit des Balls mit dem Schläger über der Rahmenposition für einen erfindungsgemäßen Schläger und für herkömmliche Schläger dargestellt ist.

The racket according to the invention will now be described by way of example with reference to preferred embodiments with reference to the drawings. Show it:

Fig. 1

a schematic front view of a racket according to the invention, in which a dial for indicating the respective frame positions is located;

Fig. 2a

an enlarged view in perspective view of a portion of the frame of a racket according to the invention with trough-shaped indentation, wherein the opening is not shown;

Fig. 2b

an enlarged view in perspective view of a portion of the frame of a racket according to the invention with trough-shaped recess and the opening;

Fig. 3

a schematic side view (view in the clothing plane) on the frame of a racket according to the invention in the region of the trough-shaped indentations;

Fig. 4

a schematic cross-sectional view of the frame profile of a racket according to the invention according to the in FIG. 2 illustrated embodiment;

Fig. 5

a sectional perspective view of the frame profile of a racket according to the invention with trough-shaped indentations and the opening;

Fig. 6a and 6b

Charts showing the relative speed values above the frame position for a racket according to the invention and for conventional rackets; and

Fig. 7a and 7b

Charts showing the contact time of the ball with the racket above the frame position for a racket according to the invention and for conventional rackets.

In the Fig. 1 shown schematic representation of the racket 2 according to the invention includes for better understanding a dial corresponding to a normal clock, wherein the 12 o'clock position (XII) is provided at the outermost free end of the racket.

The racket 2 according to the invention has a frame 4 which forms a racket head 6 and a handle section 10 preferably connected thereto via a heart area 8. The frame 4 is formed from a frame or hollow profile (see Fig. 4 ). The club head defines a clothing plane of the racket. For receiving the clothing, the frame 4 in the region of the club head 6 has a plurality of through holes 7 lying substantially in the clothing plane (FIG. Fig. 3 ) for the performance of stringed strings 9, of which in the cross section according to Fig. 4 one is shown schematically.

According to the invention, the frame profile is generally between about 2 o'clock and 4 o'clock, in particular at about 3 o'clock, or between about 8 o'clock and 10 o'clock, in particular at about 9 o'clock, in each case a pair of opposing trough-shaped indentations 12 intended. Thus, a total of four of the recesses 12 are formed on the racket 2 according to the invention. Due to the recesses 12, the frame height in the direction perpendicular to the clothing plane in this area is reduced by twice the amount T of each trough-shaped indentation 12. The depths T of the opposing indentations 12 are preferably dimensioned such that in the region of the indentations a frame height h results which is approximately 60 to 95%, preferably approximately 70 to 90%, more preferably approximately 80%, of the frame height H outside the indentations 12 is. Consequently, the racket according to the invention, for example, at a frame height H of 20 mm in the region of the opposing recesses 12 a frame height h of about 16 mm.

The length L of the trough-shaped recesses along the frame is typically in the range of 10 mm to 30 mm, preferably between 12 mm and 25 mm, and more preferably between 15 mm and 23 mm. It is further preferred to form the trough-shaped indentation 12 substantially in the form of a circular arc when viewed in the clothing plane, with radii R in the range between 15 mm and 25 mm being preferred. A radius of about 20 mm is currently particularly preferred.

The width B of the trough-shaped recess, i. their dimension in the direction of the string through holes or perpendicular to the direction of the frame at the relevant location, depends essentially on the cross-sectional shape of the frame profile and the depth T of the recess 12 from. However, the trough-shaped recesses 12 typically extend substantially over the entire width of the frame profile.

For a racket with a frame height H of 19 mm and a radius of the trough-shaped recess of 20 mm results in a trough length L of about 17 mm and a case depth T of about 1.9 mm, so that the frame height h in the region of the opposite recesses 12 is about 15.2 mm, ie about 80% of the frame height H. For a racket with a frame height H of 28.5 mm results for the same radius for the trough-shaped recesses a trough length L of about 20.6 mm and a bowl depth of about 2.85 mm. The remaining frame height h in the region of the indentations 12 is thus about 22.8 mm, which is also a Reduction of the frame height to 80% of lying outside the indentations 12 frame height H corresponds.

In Fig. 2a a recess 12 is shown in more detail on the frame 4 of the racket according to the invention.

In the in the FIGS. 2b . 4 and 5 illustrated embodiment of the racket 2 according to the invention, an opening 14 is further provided in the trough 12, which extends substantially perpendicular to the clothing plane or to the through holes 7 for the strings 9 through the frame profile to the opposite trough 12, preferably centrally through the Hopper. The opening 14 is, as in Fig. 2b shown formed in the form of a substantially circular cylindrical through hole. The bore extends through the two opposite walls of the frame profile, thereby forming two opposite, aligned holes in the frame profile. The diameter of the opening is preferably in the range between about 2 mm and 8 mm, more preferably between 3 mm and 6 mm.

To avoid the entry of dirt and / or moisture into the interior of the frame profile, an insert 16 is preferably provided in the opening 14, which terminates the frame profile to the interior of the opening 14. The insert 16 is preferably tubular, i. with a passage opening 18, formed. However, it can also be designed as a "lid" or solid profile. The insert 16 is typically made of a soft, resilient material so that it does not significantly affect the characteristics of the racquet in this area. Preferably, a transparent plastic (e.g., rubber) is used for this purpose. The tubular insert 16 preferably has a small wall thickness of e.g. about 0.5 to 1.5 mm, preferably from about 0.5 to 1 mm, on.

Another way to provide the opening 14 in the frame 4 of the racket 2 according to the invention is, instead of a through hole through the frame profile at the front and back of the frame each individual holes train. As already mentioned above, two opposite holes together form an opening 14 extending through the frame profile. The holes may have any desired shape, but are preferably substantially arcuate or trough-shaped when viewed parallel to the clothing plane. This can be realized for example by milling or sawing.

The length of the holes along the frame is preferably in the range between 1 mm and 10 mm, more preferably between 3 mm and 7 mm. The greatest depth of a hole corresponds at least to the wall thickness of the frame profile, so that the frame profile is at least partially completely removed to expose an opening in the interior of the frame profile. The maximum depth of the hole is preferably the depth up to a groove 20 (FIG. Fig. 4 ) for receiving a headband 22 ( Fig. 3 ) of the bat practicable. The width of the hole is preferably in the range between 3 mm and 7 mm.

Also in the case of such holes, it is preferable to provide the opening with a substantially tubular insert or lid, the shape of which may be adapted to the shape of the hole, so that neither dirt nor moisture can get into the interior of the frame profile.

The trough-shaped recesses 12 are preferably formed during molding of the racket frame 4 in the frame profile, for example by providing a corresponding bulge in the mold. Furthermore, it may be preferable to provide in the region of the recesses 12 one or more reinforcing layers in the material forming the frame profile. For this purpose, for example carbon fiber material, glass or aramid fabric and / or a unidirectional prepreg at an angle of ± 45 ° to the longitudinal frame extension (ie helically in the wall of the frame profile) are incorporated into the racket frame forming frame profile. This is preferably done by superimposing the different layers of frame material and reinforcing material and then rolling the superimposed materials into a "tube" which then inserted into the molding press and pressed under the action of temperature and pressure to the frame.

The racket according to the invention is particularly advantageous in terms of its improved ball guidance and the ability to give the ball excellent accelerations. The advantageous properties of the racket according to the invention are presumably due to the fact that the bending resistance of the frame profile is considerably lower due to the trough-shaped indentations 12 than in areas of the frame without indentations. As a result, a kind of "joint" is provided, which allows the particularly advantageous ball guide characteristic of the racket. Another advantage of the racket according to the invention lies in its improved damping.

wobei V_{ball(post_impact)} die Geschwindigkeit des Balles unmittelbar nach dem Auftreffen des Balles auf die Bespannung des Schlägers ist und V_{racket(pre_impact)} die Geschwindigkeit des Schlägers unmittelbar vor dem Treffen des Balls ist. Die Markierung auf dem in den Diagrammen gemäß Figur 6a und 6b jeweils rechts schematisch dargestellten Schläger gibt die Auftreffposition des Balls bezüglich der Längsachse des Schlägers, die durch den Griffabschnitt verläuft, an. Gemäß Figur 6a trifft der Ball etwas seitlich der Längsachse auf die Bespannung des Schlägers, wohingegen gemäß Figur 6b der Ball mittig auf die Bespannung des Schlägers trifft. Auf der Abszisse sind die Auftreffpositionen des Balls aufgetragen, wobei die Skala jeweils rechts mit null beginnt, das heißt am Griffende, und zum Kopfende des Schlägers hin der Abstand in Millimetern angegeben ist. Dies ist anhand des in den Figuren 6a und 6b jeweils unten schematisch dargestellten Schlägers leicht nachvollziehbar.In Figures 6a and 6b Relative speed values of the racket according to the invention are shown graphically at different frame positions compared to conventional rackets. The relative speed is in Figures 6a and 6b specified as ACOR, where: $$\mathrm{ACOR}\mathrm{=}\frac{{\mathrm{V}}_{\mathrm{ball}\left(\mathrm{post\_impact}\right)}}{{\mathrm{V}}_{\mathrm{racket}\left(\mathrm{pre\_impact}\right)}}-1$$

where V _{ball (post_impact) is} the speed of the ball immediately after the ball hits the racket and V _{racket (pre_impact) is} the speed of the racket immediately before the ball _hits . The marking on the in the diagrams according to FIGS. 6a and 6b each right schematically illustrated racket indicates the impact position of the ball with respect to the longitudinal axis of the racket, which extends through the handle portion to. According to FIG. 6a the ball hits slightly laterally of the longitudinal axis on the fabric of the racket, whereas according to FIG. 6b The ball hits the center of the clothing of the racket. On the abscissa, the impact positions of the ball are plotted, the scale each begins on the right with zero, that is, at the end of the handle, and the head of the racket towards the distance in millimeters is indicated. This is based on the in the Figures 6a and 6b each below schematically illustrated racket easy to follow.

The uppermost curve (white) in Figures 6a and 6b each represents the relative speed of a racket according to the invention, which in the Figures 6a and 6b denoted by "LM8 ++".

In comparison, a conventional "LM 8" racket was tested, ie the same racket for which the gray curve in Figures 6a and 6b applies, which, however, has no indentations. The curve appears in Figures 6a and 6b black and lies below the white curve for the same racket with indentations.

The lowest curve in Figures 6a and 6b (gray) represents a prior art racket approximately as appreciated in the introduction to the description EP 0 676 222 B1 As from the Figures 6a and 6b recognizable, this racket has a relative to the racket according to the invention significantly reduced relative speed and thus a comparatively poorer acceleration capacity. This applies both to the lateral impact of the ball ( FIG. 6a ) as well as for the central ball impact ( FIG. 6b ) over the entire measuring range along the club head.

In FIGS. 7a and 7b In each case, the contact time or dwell time of the ball is shown on the fabric of the racket in milliseconds above the racket position, wherein the impact positions of the ball in the same manner as in the Figures 6a and 6b are shown and turn on Figure 7a Ball impact points laterally of the longitudinal axis of the racket and at FIG. 7b central ball impact points were measured. As in Figure 7a recognizable, the contact time of the racket according to the invention (white line) over the entire measuring range above that of a same racket without indentations (black line) and also almost over the entire measuring range significantly above that of the conventional racket according to the prior art after EP 0 676 222 B1 (gray line), ie the contact time is longer in the racket according to the invention. For a central impact as shown by FIG. 7b this characteristic is even more pronounced. Here is the Contact time of the ball on the club according to the invention (white line) is significantly longer than in the comparison racket without indentations (black line) and even significantly longer than in the racket according to the prior art EP 0 676 222 B1 (gray line). This increased dwell time or contact time of the ball on the fabric of the racket according to the invention leads to a significantly improved ball control, so that not only the acceleration of the ball but also the accuracy of the club according to the invention over the prior art is significantly increased.

Claims (14)

1. A racket for ball games including a frame (4) having a racket head (6) and a handle portion (10) connected thereto and being formed of a frame profile, wherein the racket head (6) defines a stringing plane and the frame profile comprises four trough-shaped depressions (12) in the area of the racket head (4), said trough-shaped depressions (12) being arranged opposite to one another in pairs and essentially symmetrical with respect to the longitudinal axis of the racket (2), wherein each pair of opposite depressions (12) has an opening (14) extending essentially perpendicular with respect to the stringing plane of the racket (2) through the frame profile, characterized in that a first pair of trough-shaped depressions (12) is provided between two o'clock and four o'clock and a second pair of trough-shaped depressions is provided between eight o'clock and ten o'clock, wherein two of the trough-shaped depressions (12) are formed on a front side of the racket and two of the trough-shaped depressions (12) are formed on an opposite rear side of the racket.
2. The racket according to claim 1, wherein a first pair of trough-shaped depressions (12) is formed at about three o'clock and a second pair of through-shaped depressions (12) is formed at about nine o'clock, wherein two of the trough-shaped depressions (12) are formed on a front side of the racket and two of the trough-shaped depressions (12) are formed on an opposite rear side of the racket.
3. The racket according to claim 1, wherein a first pair of trough-shaped depressions (12) is displaced from the three o'clock position by about 2 to 3 cm towards a free end of the racket (2) and a second pair of trough-shaped depressions (12) is displaced from the nine o'clock position by about 2 to 3 cm towards the free end of the racket (2), wherein two of the trough-shaped depressions (12) are formed on a front side of the racket and two of the trough-shaped depressions (12) are formed on an opposite rear side of the racket.
4. The racket according to any one of claims 1 to 3, wherein the opposite trough-shaped depressions (12) each have a depth (T), so that when being viewed in a direction parallel to the stringing plane, there is a reduced frame height (h) ranging approximately between 60% and 95%, preferably between 70% and 90% and more preferably at 80% of a frame height (H) next to the depressions (12).
5. The racket according to any one of claims 1 to 4, wherein a length (L) of each trough-shaped depression (12) along the frame profile ranges between 10 mm and 30 mm, preferably between 12 mm and 25 mm and more preferably between 15 mm and 23 mm.
6. The racket according to any one of claims 1 to 5, wherein, when being viewed in the direction parallel to the stringing plane, each of the trough-shaped depressions is essentially circular and has a circular arc radius within the range between 15 mm and 25 mm, preferably of about 20 mm.
7. The racket according to any one of claims 1 to 6, wherein the opening is circular cylindrical and has a diameter (D) ranging between 2 mm and 8 mm, preferably between 3 mm and 6 mm.
8. The racket according to any one of claims 1 to 7, wherein an essentially tubular insert (16) is provided in the opening (14) in order to close the frame profile towards the interior.
9. The racket according to any one of claims 1 to 8, wherein in the area of the four trough-shaped depressions (12) the frame profile comprises one or more strengthening layer(s).
10. The racket according to claim 9, wherein the strengthening layer comprises a woven fabric made of carbon fiber, glass or aramid and/or a unidirectional prepreg and is arranged at an angle of ± 45° with respect to the longitudinal direction of the frame.
11. A process for producing a racket, in particular according to any one of claims 1 to 10, comprising the following steps:

    (a) forming a frame (4) consisting of a frame profile and comprising a racket head (6) and a handle portion (10) connected thereto; and

    (b) providing four trough-shaped depressions (12) which are arranged on the racket head (6) opposite to one another in pairs and essentially symmetrical with respect to the longitudinal axis of the racket (2), wherein a first pair of trough-shaped depressions (12) is provided between two o'clock and four o'clock and a second pair of trough-shaped depressions is provided between eight o'clock and ten o'clock, wherein two of the trough-shaped depressions (12) are formed on a front side of the racket and two of the trough-shaped depressions (12) are formed on an opposite rear side of the racket, wherein the frame profile comprises at least one opening (14) per depression (12).
12. A process according to claim 11, wherein the trough-shaped depressions (12) are formed simultaneously with the frame (4) during the step of molding the frame profile in a molding press.
13. The process according to claim 11 or 12, wherein the opening is formed by drilling, milling or sawing.
14. The process according to any one of claims 11 to 13, wherein an essentially tubular insert is introduced into the opening in order to close the frame profile towards the interior.

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