BALL GAME RACKET FRAME, BALL GAME RACKET, AND METHOD FOR MANUFACTURING A BALL GAME RACKET FRAME

- Head Technology GMBH

A ball game racket frame includes a head portion, a grip portion and a shaft portion which connects the grip portion and the head portion. The ball game racket frame is at least partially made of at least one layer of a plurality of fibers which are randomly orientated and intertwined within the layer. According to further aspects, a ball game racket includes the ball game racket frame according to any of the embodiments described herein and a string bed plane comprising a plurality of strings which are attached to at least a portion of the head portion of the ball game racket frame. The string bed plane provides at least one striking surface for striking a game ball. According to yet further aspects, a method for manufacturing a ball game racket frame is disclosed.

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Description
BACKGROUND

Ball game rackets are available for a wide range of different leisure activities and/or sports. For instance, there is a relatively large market for tennis rackets with a broad selection of different available tennis rackets. Other leisure activities and/or sports, such as, but not limited to, badminton, squash, and table tennis, also form sizable markets with a variety of different ball game rackets available for users to choose from. Moreover, in recent years, padel tennis, sometimes also referred to as padel or pádel, has also grown in popularity.

Ball game rackets may be made from a variety of different materials. Simple, relatively low-priced ball game rackets are typically made of plastic or metal, such as aluminum. High-performance ball game rackets, on the other hand, are often made of more sophisticated and/or expensive material, such as carbon fiber, glass fiber and/or ceramic.

Such high-performance ball game rackets, in large part due to their more sophisticated and/or optimized material, offer a relatively light-weight construction while providing a relatively high stiffness to the respective ball game racket, e.g., which may reduce deformation of the ball game rackets during use, i.e., while striking a ball therewith. To achieve a relatively light-weight construction with a relatively high stiffness, manufactures of ball game rackets, at least in high-end ball game rackets, in recent years have focused mainly on the use of composite materials, in particular carbon fiber reinforced materials, in ball game rackets.

However, ball game rackets made of such high-strength materials do not have all of the qualities which a user may desire and/or expect from the respective ball game racket for the user's respective sport and/or leisure activity and/or which may be advantageous, e.g., with respect to the performance, quality and/or comfort of the respective ball game racket during use and/or the user's skills and/or experience.

Thus, based on the prior art, there remains a need to further improve the qualities of ball game rackets.

SUMMARY OF THE DISCLOSURE

It is therefore an object of the present invention to provide a ball game racket having improved characteristics during use thereof.

This object is achieved by a ball game racket frame defined by the features of claim 1. Variations and further developments are defined by the features of the dependent claims.

The ball game racket frame may include a head portion, a grip portion and a shaft portion which connects the grip portion and the head portion. The ball game racket frame may be at least partially made of at least one layer of a plurality of fibers which are randomly orientated and intertwined within the layer.

The term “randomly orientated”, within the meaning of the present disclosure, means that the fibers are provided in the layer of fibers in arbitrary, and thus multiple, directions, i.e., in a substantially non-unidirectional manner. This may be achieved, e.g., by arbitrarily arranging the fibers in the layer of fibers during manufacturing. However, the term “randomly orientated” does not exclude that some of the fibers provided in the layer of fibers may have the same orientation, which may occur, e.g., unintentionally during manufacturing. In other words, the fibers provided in the layer of fibers are still considered to be randomly orientated, even if (only) some of the fibers provided in the layer of fibers have the same orientation.

The term “intertwined”, within the meaning of the present disclosure, means that the fibers are at least partially connected and/or in contact with each other and/or overlap each other. This may provide a certain degree of mutual cohesiveness among the fibers in the layer. Preferably, at least some of the fibers may be stacked on top of each other in at least a section of the fibers and/or in at least a section of the layer of fibers. The fibers may be at least partially, e.g., at least some of the fibers and/or at least in at least one or more sections of the layer of fibers, pressed together, e.g., as a mat, or fiber mat, or a sheet of fibers, or fiber sheet.

The fibers provided in the layer of fibers, which are randomly orientated and intertwined within the layer, are preferably arranged substantially in a single plane, when the layer of fibers is spread on a substantially even surface before the layer of fibers is applied to the ball game racket frame.

As mentioned at the beginning, in recent years, the development of ball game rackets, in particular high-end ball game rackets, has been focused on the use of fiber reinforced composite materials, in particular carbon fiber reinforced materials. The fiber reinforced composite materials often include one or more layers of fibers which are substantially unidirectionally orientated in each layer of fiber reinforced composite material. This generally provides a relatively high degree of stiffness to the ball game racket in a direction which extends along the length of the fibers. Moreover, the weight of the ball game racket is kept relatively low due to the relatively low weight of fiber reinforced composite material.

However, there are several drawbacks to the fiber reinforced composite materials provided in the ball game rackets known from the prior art, in particular in which the fibers are unidirectionally orientated in the respective composite material. For instance, composite materials which include unidirectionally orientated fibers often have a relatively high degree of orthotropy, meaning that one or more properties of the layer(s) of the composite material, e.g., the strength, stiffness, and/or one or more further properties of the layer(s) of the composite material, differ along multiple, e.g., two or three, orthogonal axes in at least a section of the layer(s) of composite material. For instance, the fiber reinforced composite materials which have been used in the ball game rackets known from the prior art, in particular in which the fibers are unidirectionally orientated in the respective composite material, have a relatively low degree of dampening and/or shock absorption at least in one or more directions along the ball game racket, in particular the ball game racket frame. This may reduce, or at least limit, the playing characteristics, e.g., the playability of the ball game racket frame. Moreover, this may promote a transfer of forces and/or moments through the ball game racket frame, e.g., to the user who is gripping the respective ball game racket frame, which may be undesirable, e.g., since this may reduce the user's comfort and/or may cause injuries.

In some ball game rackets, a plurality of layers of unidirectionally fibers are arranged in a stacked manner, wherein the plurality of stacked layers of unidirectionally fibers are arranged such that the direction of the fibers in the respective layers may vary from layer to layer, i.e., the fibers of one layer may be orientated in a first direction and the fibers of a further layer may be orientated in a second direction which is different than the first direction, e.g., the fibers of one layer may be orientated at an angle which is greater than 0, e.g., 90°, with respect to the fibers of a further layer. However, such an arrangement also has a relatively low degree of dampening and/or shock absorption due to the unidirectional arrangement of the fibers in each layer.

Furthermore, the fiber reinforced composite materials which have been used in ball game rackets in the prior art, in particular in which the fibers are unidirectionally orientated in the respective composite material, have several drawbacks with respect to processing the respective material(s) and/or forming the ball game racket frame out of the respective composite material. For instance, fiber reinforced composite materials in which the fibers are unidirectionally orientated often have a relatively low drapability which may hamper the manufacturing process of the ball game racket and/or may negatively affect one or more properties of the manufactured ball game racket frame.

Providing at least one layer of a plurality of fibers which are randomly orientated and intertwined within the layer may improve the above-identified drawbacks. In particular, providing randomly orientated fibers in the at least one layer of fibers in the ball game racket frame provides the fibers in arbitrary, and thus multiple, directions, i.e., in a non-unidirectional manner, within each layer of fibers in the ball game racket (frame). This may improve the degree of dampening and/or the shock absorption properties of the ball game racket frame, e.g., since forces and/or moments which may be exerted onto the ball game racket frame, e.g., by striking a game ball with the respective ball game racket, may not be transferred along the fibers in a single direction in each layer of fibers due to the random orientation of the fibers in each layer. Instead, the randomly orientated fibers may distribute the forces and/or moments more evenly within each layer, which may improve the degree of dampening and/or the shock absorption properties of the ball game racket frame. This may increase the impact characteristics of the ball game racket frame, in particular when a game ball strikes a striking surface of the ball game racket.

Furthermore, the randomly orientated and intertwined fibers may also improve the deformability and/or the handleability of the material, i.e., the at least one layer of a plurality of randomly orientated and intertwined fibers, e.g., the drapability of the material, during manufacturing and/or prior to manufacturing the ball game racket frame. For instance, improving the drapability of the material may allow to achieve smaller radii in at least sections of the ball game racket frame and/or may facilitate providing relatively small radii in at least sections of the ball game racket frame.

Moreover, providing at least one layer of a plurality of fibers which are randomly orientated and intertwined within the layer may reduce and/or limit a degree of orthotropy of the layer of fibers, more specifically of the ball game racket frame, and/or may increase a degree of isotropy of the layer of fibers, more specifically of the ball game racket frame, in at least a section of thereof. This may provide a more balanced ball game racket (frame), e.g., compared with layers of composite material which only include unidirectionally orientated fibers.

One or more layers of a plurality of fibers which are randomly orientated and intertwined may be provided in a section of the ball game racket which at least partially defines at least one striking structure having at least one striking surface configured to strike a game ball during use of the ball game racket. Alternatively, or additionally, one or more layers of a plurality of fibers which are randomly orientated and intertwined may be provided in a section of the ball game racket which is arranged outside and/or at a distance from the at least one striking structure, more specifically the at least one striking surface. For instance, the striking surface(s) of a number of ball game rackets, e.g., tennis rackets, badminton rackets, etc., are provided with a string bed plane comprising a plurality of strings which are attached to at least a portion of the head portion of the ball game racket frame. In this case, the one or more layers of a plurality of fibers which are randomly orientated and intertwined would be provided in a section of the ball game racket frame which is arranged outside and/or at a distance from the at least one striking structure, more specifically the at least one striking surface, i.e., the string bed plane.

However, in a number of further ball game rackets, the respective striking surface(s) is/are at least partially defined or provided by a substantially solid structure, which is preferably continuous and uninterrupted at least section-wise, e.g., having a thickness, at least section-wise, of at least 5 mm, preferably at least 10 mm, and optionally having one or more holes extending at least partially therethrough, such as in padel tennis rackets and/or table tennis rackets. In this case, one or more layers of a plurality of fibers which are randomly orientated and intertwined may be provided in a section of the ball game racket which defines at least one striking structure having at least one striking surface configured to a strike a game ball during use of the ball game racket. In other words, the one or more layers of a plurality of fibers which are randomly orientated and intertwined may be arranged behind the striking surface, in a direction of a flight of a game ball which is directed towards the striking surface. Alternatively, or additionally, one or more layers of a plurality of fibers which are randomly orientated and intertwined may at least partially define the striking surface(s).

The ball game racket frame may include a plurality of layers of a plurality of fibers which are randomly orientated and intertwined within the layer. For instance, a plurality of layers of a plurality of fibers may be stacked on top of each other and/or a plurality of layers may each be arranged in different sections or the ball game racket frame, e.g., one or more first layers of fibers may be arranged in a first section of the ball game racket frame, e.g., in the head portion, and one or more second layers of fibers may be arranged in at least a second section of the ball game racket frame, e.g., in the a grip portion and/or the shaft portion.

The grip portion is configured to be gripped by a user, preferably by a user's hand, either by one hand or both hands of the user. For this purpose, the grip portion may include features which may facilitate gripping thereof, such as suitable dimensions, a suitable shape which suits the user's body part used to grip the grip portion and/or features which may reduce slipping between the user's body part which grips the grip portion, e.g., the user's hand(s), and the grip portion.

Preferably, the grip portion extends along a longitudinal axis to the shaft portion. In this case, the grip portion and the shaft portion may be aligned and may share a common longitudinal axis.

Alternatively, the grip portion and the shaft portion may be angled relative to each other, instead of being aligned and sharing a common longitudinal axis. For instance, the grip portion and the shaft portion may be angled relative to one another by at least 5′, preferably at least 10°, more preferably at least 15°, most preferably at least 20°. Alternatively, or additionally, the angle formed between the grip portion and the shaft portion may be at most 5°, more preferably at most 10°, more preferably at most 15°, most preferably at most 20°.

Preferably, the grip portion merges to the shaft portion. In other words, the grip portion may abut the shaft portion. However, it is also feasible that the grip portion and the shaft portion are separate, e.g., spaced from each other, preferably along a common longitudinal axis.

Preferably, the shaft portion extends and/or merges to the head portion. In other words, the shaft portion may abut the head portion at least partially.

The shaft portion may split into two sections leading to the head portion. This section of the shaft portion is often referred to as a throat portion.

The throat portion may be open, i.e., an opening may be formed between the two split sections. Alternatively, the throat portion may be closed. In this case, the throat portion does not include said opening.

The head portion may provide at least one striking surface, such as a substantially planar surface, for striking a ball during use in a ball game sport and/or leisure activity. The striking surface does not have to be substantially planar. Instead, the striking surface may be curved and/or angled in one or more sections thereof.

Alternatively, or additionally, one or more additional means may be provided for providing a striking surface for striking a ball during use in a ball game sport and/or ball game activity. For instance, a string bed plane comprising a plurality of strings may be attachable to at least a portion of the head portion. Such a string bed plane is commonly used for, amongst others but not limited to, tennis rackets, squash rackets and badminton rackets. The strings may be attached to a peripheral section of the head portion and may extend across an opening defined within the peripheral section of the head portion.

Alternatively, the head portion may have a solid surface, which is preferably continuous and uninterrupted at least section-wise, instead of a string bed plane, which may provide the striking surface for striking a ball during use in a ball game sport and/or ball game activity, such as for padel tennis, table tennis and pickleball. Such a striking surface may also have at least one opening formed therein, which is preferably configured as a through-hole, the opening preferably being smaller than the size of the ball to be struck by the corresponding ball game racket.

Preferably, the layer of fibers, which are randomly orientated and intertwined within the layer, is configured as a fiber veil, preferably a carbon fiber veil and/or a glass fiber veil. The carbon fiber veil may include a plurality of carbon fibers which are randomly orientated and intertwined within the respective layer of fibers. The glass fiber veil may include a plurality of glass fibers which are randomly orientated and intertwined within the respective layer of fibers. The term “fiber veil”, e.g., a carbon fiber veil and/or a glass fiber veil, is to be understood as a relatively thin ply of continuous material including strands of fibers which are preferably randomly looped and held together as a layer with a light binder. The fiber veil may be so thin such that it is at least partially transparent and/or translucent in its raw state, i.e., when viewing a single layer of carbon layer, i.e., before the layer of carbon has been applied to the ball game racket frame. The fiber veil may also be referred to as “fiber tissue”, e.g., carbon tissue, and/or “surfacing veil” in the field. The fiber veil is preferably configured as a mat or sheet.

Preferably, the layer of fibers, which are randomly orientated and intertwined within the layer, is configured as a non-woven fabric material. The non-woven fabric material may include at least one bonding agent for bonding the fibers at least partially together to form a layer of fibers.

Preferably, the fibers, which are randomly orientated and intertwined within the layer, are looped, preferably randomly looped, in the layer of fibers. The term “looped”, within the meaning of the present disclosure, is to be understood such that the respective fiber(s) has/have at least one redirection along a length of the respective fiber, in particular a redirection of the respective fiber by an angle which is larger than 90°, preferably an angle of at least 100°, more preferably at least 110°, more preferably at least 120°, more preferably at least 130°, more preferably at least 140°, more preferably at least 150°, more preferably at least 160′, more preferably at least 170′, most preferably at least 180°. Thus, at least a section of the respective fiber(s), e.g., a section in which the respective fiber(s) is/are redirected, may form a loop. For instance, one or more of the fibers, which are randomly orientated and intertwined within the layer, may extend, in a first section of the fiber, in a first direction, and, in at least a second section of the fiber, in a second direction, wherein the second direction may be angled with respect to the first section by one of the above-identified angles or angle ranges. The term “randomly looped”, within the context of the present disclosure, is to be understood such that various fibers, which are randomly orientated and intertwined within the layer, are looped arbitrarily, e.g., by non-purposely looping the fibers and/or looping the fibers without a target looping shape and/or target looping dimensions. In other words, one or more first fibers are looped in a manner, i.e., at an angle, which differs from the manner in which one or more second fibers are looped, i.e., the one or more second fibers may be looped at a different angle than the one or more first fibers.

Preferably, the fibers, which are randomly orientated and intertwined, are at least partially bonded together, preferably by one or more bonding materials which preferably include a thermoplastic material, a resin and/or a thermosetting material. This may increase the cohesiveness of the fibers in the layer. Preferably, the fibers, which are randomly orientated and intertwined, are at least partially embedded in at least one matrix in the layer of fibers. The one or more bonding materials may further enhance the dampening and/or shock absorption properties of the ball game racket frame.

Preferably, the fibers which are randomly orientated and intertwined, including any bonding material which may be provided to bond the fibers together, account for at least 20 wt %, preferably at least 30 wt %, more preferably at least 40 wt %, more preferably at least 50 wt %, most preferably at least 60 wt %, of a total weight of at least a segment of the ball game racket frame. Configuring the ball game racket frame to have a relatively large proportion of fibers, which are randomly orientated and intertwined, including the bonding material(s), may allow the positive effects of the fibers which are randomly orientated and intertwined which can be provided to the ball game racket frame to be increased. For instance, a relatively large amount of fibers which are randomly orientated and intertwined, may be achieved by providing a relatively high packing density of fibers which are randomly orientated and intertwined in the ball game racket frame. Configuring a layer of fibers which are randomly orientated is often disadvantageous for the packing density of fibers, i.e., only a relatively low packing density of fibers may be achieved by randomly orientating the fibers. The inventors have discovered means to increase the packing density of the fibers within the layer, e.g., by providing the fibers with one or more certain shapes and/or one or more dimensions, e.g., relatively short fibers, and/or by one or more processing steps, such as pressing the fibers together.

Preferably, the layer(s) of fibers which are randomly orientated and intertwined, including any bonding material which may be provided in the layer(s) to bond the fibers together, account for at least 10 vol %, preferably at least 20 vol %, more preferably at least 30 vol %, more preferably at least 40 vol %, more preferably at least 50 vol %, most preferably at least 60 vol %, of a total volume of the ball game racket frame in at least one cross-section of the ball game racket frame. A volume percentage (vol %) of the layer(s) of fibers, with respect to a total volume of the ball game racket frame in at least one cross-section of the ball game racket frame, may be determined via computer tomography, e.g., by scanning the concerned cross-section(s) of the ball game racket frame by means of a computer tomographic device and determining the volume percentage (vol %) of the layer(s) of fibers, with respect to a total volume of the ball game racket frame in the concerned cross-section(s) of the ball game racket frame, e.g., by means of suitable analysis software, e.g., by calculating a ratio of a sum of the areas of the layer(s) of fibers, which are randomly orientated and intertwined, in the concerned cross-section to the total area of the concerned cross-section. For instance, a suitable computer tomographic device may be a TomoScope® XS by Werth Messtechnik GmbH and a suitable analysis software for use with the computer tomographic device may be Avizo® by FEI Visualization Sciences Group.

Preferably, the fibers, which are randomly orientated and intertwined, include carbon fibers and/or glass fibers.

Preferably, the fibers, which are randomly orientated and intertwined, include recycled fibers, preferably recycled carbon fibers and/or recycled glass fibers. Using recycled carbon fibers and/or recycled glass fibers may reduce the cost of manufacturing the ball game racket frame and may reduce the ecological footprint of the ball game racket frame, which may increase the eco-friendliness of the ball game racket frame. Moreover, using recycled carbon fibers and/or recycled glass fibers, e.g., from used ball game rackets which are discarded, may eliminate the need to dispose of the carbon fibers and/or the glass fibers. This may be advantageous, in particular since the requirements, e.g., the provisions, for disposing carbon fibers and/or glass fibers may be particularly stringent, at least in some countries and/or regions. This may further reduce waste and/or the cost of manufacturing the ball game racket frame and may make manufacturing the ball game racket frame less dependent from material suppliers, which may make manufacturing the ball game racket frame less susceptible to problems in the supply change, e.g., material shortages. Moreover, carbon fibers and/or glass fibers, including recycled carbon fibers and/or recycled glass fibers, may provide a relatively high level of strength and/or durability to the ball game racket frame.

Preferably, the recycled fibers account for at least 20 wt %, preferably at least 25 wt %, more preferably at least 30 wt %, more preferably at least 35 wt %, more preferably at least 40 wt %, more preferably at least 45 wt %, most preferably at least 50 wt %, of a total weight of all fibers included in the ball game racket frame.

The fibers, which are randomly orientated and intertwined, may not be limited to a particular fiber length or average fiber length in order to achieve an advantageous effect based on the fibers being randomly orientated and intertwined within the layer of fibers. For instance, the fibers, which are randomly orientated and intertwined, may have a length or average length from 2 mm to 130 mm. However, the inventors have found that limiting the length or average length of the fibers, which are randomly orientated and intertwined, may provide further advantageous effects, e.g., by interrupting a transfer of forces and/or moments along each fiber substantially at the end of each fiber. This may further increase a degree of dampening and/or shock absorption of the ball game racket frame which may increase the playing characteristics, e.g., the playability, of the ball game racket (frame). Moreover, this may increase a degree of comfort of the ball game racket (frame) to the user. Preferably, the fibers, which are randomly orientated and intertwined, have an average length of no more than 30 mm, more preferably no more than 25 mm, more preferably no more than 20 mm, more preferably no more than 15 mm, more preferably no more than 12 mm, more preferably no more than 10 mm, more preferably no more than 8 mm, more preferably no more than 6 mm, most preferably no more than 4 mm.

Preferably, each fiber of the fibers, which are randomly orientated and intertwined, has a length of no more than 30 mm, more preferably no more than 25 mm, more preferably no more than 20 mm, more preferably no more than 15 mm, more preferably no more than 12 mm, more preferably no more than 10 mm, more preferably no more than 8 mm, more preferably no more than 6 mm, most preferably no more than 4 mm. This may further increase the degree of dampening and/or shock absorption of the ball game racket frame, e.g., by interrupting a transfer of forces and/or moments along each fiber substantially at the end of each fiber.

Preferably, the ball game racket frame is at least partially made of at least one layer of a plurality of substantially unidirectionally orientated fibers in at least one or more sections of the ball game racket frame. This may allow the advantageous properties of an arrangement of at least one layer of randomly orientated and intertwined fibers, such as an increased degree of dampening and/or shock absorption of the ball game racket frame, to be combined with one or more advantageous properties of unidirectionally orientated fibers, such as a relatively high degree of strength and/or durability. Alternatively, or additionally, this may allow one or more undesirable properties of the randomly orientated and intertwined fibers, e.g., one or more properties which may negatively the playability of the ball game racket, to be compensated by the unidirectionally orientated fibers and/or vice versa.

Preferably, the layer of fibers, which are randomly orientated and intertwined, is embedded between layers of prepregs of a composite material, the composite material preferably including a plurality of carbon fibers and/or a plurality of glass fibers. This may provide a relatively high degree of strength to the ball game racket frame, while achieving a relatively high degree of dampening and/or shock absorption of the ball game racket frame by means of the embedded layer of fibers which are randomly orientated and intertwined.

Preferably, the ball game racket frame is at least partially made of a plurality of fibers which are braided and/or a plurality of fibers which are woven. This may further balance the properties of the ball game racket frame. For instance, braided fibers and/or woven fibers may provide a relatively soft and/or cushioning, and thus, e.g., shock-absorbing, material to the ball game racket frame. A plurality of fibers which are braided and/or a plurality of fibers which are woven may be configured as one or more layers in the ball game racket frame. Alternatively, or additionally, a plurality of fibers which are braided and/or a plurality of fibers which are woven may be distributed within the ball game racket frame, e.g., strands of braided fibers and/or strands of woven fibers may be distributed within the ball game racket frame.

Preferably, the layer of fibers, which are randomly orientated and intertwined, has a ratio of a strength or a stiffness of the layer of fibers in a first direction to a strength or a stiffness of the layer of fibers in a second direction of no more than 12, more preferably no more than 11.5, more preferably no more than 11, more preferably no more than 10.5, more preferably no more than 10, more preferably no more than 9.5, more preferably no more than 9, more preferably no more than 8.5, more preferably no more than 8, more preferably no more than 7.5, more preferably no more than 7, more preferably no more than 6.5, more preferably no more than 6, more preferably no more than 5.5, more preferably no more than 5, more preferably no more than 4.5, more preferably no more than 4, more preferably no more than 3.5, more preferably no more than 3, preferably no more than 2.5, more preferably no more than 2, more preferably no more than 1.8, more preferably no more than 1.6, most preferably no more than 1.4, the first direction extending substantially perpendicularly to the second direction and the first direction and the second direction preferably lying in a single plane. This may reduce and/or limit a degree of orthotropy of the layer of fibers. This may ensure that the ball game racket frame is not considerably weaker, i.e., outside of the above-identified ratios, in the second direction compared with the first direction. This may provide a relatively balanced ball game racket frame. Moreover, this may ensure that the degree of dampening and/or shock absorption of the ball game racket frame is relatively high, in particular since the above-identified ratios may be achieved by providing in the ball game racket frame a relatively large amount of fibers which are randomly orientated and intertwined and/or a relatively large proportion of fibers which are randomly orientated and intertwined, with respect to the total material in the respective cross-section of the ball game racket frame, and/or by limiting the amount of unidirectionally orientated fibers provided in the ball game racket frame. Preferably, the ratio of strength or stiffness of the layer of fibers in the first direction to strength or stiffness of the layer of fibers in the second direction is determined based on a ratio of a Young's module E of the layer of fibers in the first direction to a Young's module E of the layer of fibers in the second direction. The Young's moduli of the layer of fibers may be determined by any method known in the art.

Preferably, the layer of fibers, which are randomly orientated and intertwined, has a ratio of a strength or a stiffness of the layer of fibers in a first direction to a strength or a stiffness of the layer of fibers in a second direction from 1.4 to 12, more preferably from 1.4 to 9, more preferably from 1.4 to 6, more preferably from 1.4 to 3, the first direction extending substantially perpendicularly to the second direction and the first direction and the second direction preferably lying in a single plane.

Preferably, the head portion, the shaft portion and/or the grip portion include(s) at least one layer of the of at least one layer of a plurality of fibers which are randomly orientated and intertwined. This may provide an increased degree of dampening and/or shock absorption of the ball game racket frame in the respective portion(s) by improving a distribution of forces and/or moments and/or by at least partially interrupting a transfer of forces and/or moments in the head portion, the shaft portion and/or the grip portion. Selectively providing the layer(s) of a plurality of fibers which are randomly orientated and intertwined in one or more certain portions of the ball game racket frame may allow the ball game racket frame to be fine-tuned and/or tailored to the respective user's desires and/or needs, e.g., to the respective user's style of play and/or experience.

The ball game racket frame may include a plurality of layers arranged in different sections of the ball game racket, wherein the layer(s) provided in a first section of the ball game racket, e.g., a section of the head portion, may purposely differ in one or more properties from the layer(s) provided in at least a second section of the ball game racket, e.g., a section of the shaft portion and/or the grip portion. For instance, a thickness of one or more layer(s) provided in a first section of the ball game racket, e.g., a section of the head portion, may intentionally differ, i.e., beyond manufacturing tolerances, in one or more properties from one or more layers provided in a second section, e.g., the shaft portion and/or the grip portion. Additionally, or alternatively, a section of the ball game racket may be provided with a plurality of layers, wherein a first layer of the plurality of layers may purposely differ in one or more properties from at least a second layer of the plurality of layers. The one or more properties may differ in one or more dimensions, e.g., a thickness, and/or a shape and/or one or more further properties, such as one or more properties related to the fibers, e.g., a density, a distribution, a length, a diameter, a degree of intertwining, a packing density, a degree of looping and/or a manner of looping, etc., of the fibers.

Preferably, the ball game racket frame includes a plurality of layers of the at least one layer of fibers, which are randomly orientated and intertwined, and a plurality of layers of fiber-reinforced prepregs, wherein the plurality of layers of fibers, which are randomly orientated and intertwined, and the plurality of layers of fiber-reinforced prepregs are stacked intermittently in at least a section of the ball game racket frame. This may provide a relatively even distribution of the properties provided by the fibers, which are randomly orientated and intertwined, and the fiber-reinforced prepregs, which may provide a relatively balanced ball game racket frame.

Preferably, the layer of fibers which are randomly orientated and intertwined, including any bonding material which may be provided to bond the fibers together, has an area weight of 20 to 150 g/m2, preferably an area weight of at least 20 g/m2, more preferably an area weight of at least 30 g/m2, more preferably an area weight of at least 40 g/m2, more preferably an area weight of at least 50 g/m2, more preferably an area weight of at least 60 g/m2, more preferably an area weight of at least 70 g/m2, more preferably an area weight of at least 80 g/m2, more preferably an area weight of at least 90 g/m2, more preferably an area weight of at least 100 g/m2, more preferably an area weight of at least 110 g/m2, more preferably an area weight of at least 120 g/m2, more preferably an area weight of at least 130 g/m2, more preferably an area weight of at least 140 g/m2, most preferably an area weight of at least 150 g/m2.

Preferably, at least one cross-section of the ball game racket frame, preferably at least one cross-section of the head portion, includes at least two layers of the fibers which are randomly orientated and intertwined. A first layer of the at least two layers, which is arranged further from a center of the cross-section than a second layer of the at least two layers, may have a greater thickness than the second layer. The first layer, which has a greater thickness than the second layer, is preferably arranged at a section of the head portion which is configured to receive one or more strings for providing a string bed plane which is configured to provide at least one striking surface for striking a game ball. This may absorb forces and/or moments and/or shocks which may be exerted onto the strings by a game ball.

Preferably, at least in a section of the ball game racket frame, the layer of fibers, which are randomly orientated and intertwined, has an average ratio of a length of the fibers in a fiber extension direction to a total length of the layer of fibers in the fiber extension direction of no more than 0.5, more preferably no more than 0.4, more preferably no more than 0.3. This may facilitate an interruption of a transfer of forces and/or moments through at least a section of the ball game racket frame, e.g., along the fibers.

Preferably, the fibers which are randomly orientated and intertwined account for at least 20 wt %, more preferably at least 30 wt %, more preferably at least 40 wt %, more preferably at least 50 wt %, most preferably at least 60 wt %, of a total weight of at least a segment of the ball game racket frame.

Preferably, the fibers which are randomly orientated and intertwined account for at least 10 vol %, preferably at least 20 vol %, more preferably at least 30 vol %, more preferably at least 40 vol %, more preferably at least 50 vol %, most preferably at least 60 vol %, of a total volume of the ball game racket frame in at least one cross-section of the ball game racket frame.

Preferably, a proportion of the fibers which are randomly orientated and intertwined and which have a length of no more than 30 mm, more preferably no more than 25 mm, more preferably no more than 20 mm, more preferably no more than 15 mm, account for at least 20 wt %, more preferably at least 30 wt %, more preferably at least 40 wt %, more preferably at least 50 wt %, most preferably at least 60 wt %, of a total weight of at least a segment of the ball game racket frame.

The object set out at the beginning is also achieved by a ball game racket including a ball game racket frame, preferably the ball game racket frame according to any of the embodiments described herein. The features, configurations and/or advantages detailed above with respect to the ball game racket frame apply accordingly to the ball game racket.

The ball game racket may include at least one striking surface for striking a game ball. The at least one striking surface may be provided by a string bed plane comprising a plurality of strings which are attached to at least a portion of the head portion of the ball game racket frame. Alternatively, the at least one striking surface may be at least partially provided by a solid surface, which is preferably continuous and uninterrupted at least section-wise, instead of a string bed plane, such as in the configuration of a padel tennis racket. Such a solid striking surface may also have at least one opening formed therein, which is preferably configured as a through-hole, the opening preferably being smaller than the size of the ball to be struck by the corresponding ball game racket.

The object set out at the beginning is also achieved by a method for manufacturing a ball game racket frame as defined by the independent claim. Variations and further developments are defined by the features of the dependent claims. The features, configurations and/or advantages detailed above with respect to the ball game racket frame and the ball game racket apply to the method accordingly.

The method may include the following steps:

    • a) providing at least one layer of a plurality of fibers which are randomly orientated and intertwined within the layer;
    • b) forming the ball game racket frame at least partially from the at least one layer of fibers.

Preferably, the method further includes the steps of providing at least one layer of a fiber-reinforced prepreg and forming the ball game racket frame at least partially from the at least one layer of fiber-reinforced prepreg. The steps of providing at least one layer of a fiber-reinforced prepreg and forming the ball game racket frame at least partially from the at least one layer of fiber-reinforced prepreg may be performed prior to steps a and b or after steps a) and b). Furthermore, one or both of the steps of providing at least one layer of a fiber-reinforced prepreg and forming the ball game racket frame at least partially from the at least one layer of fiber-reinforced prepreg may be performed between steps a) and b).

Preferably, the ball game racket frame is formed at least partially from a plurality of layers of fibers, which are randomly orientated and intertwined, and a plurality of layers of a fiber-reinforced prepreg, wherein the plurality of layers of fibers, which are randomly orientated and intertwined, and the plurality of layers of a fiber-reinforced prepreg are stacked intermittently in at least a section of the ball game racket.

The following list of aspects provides alternative and/or further features of the invention:

A ball game racket frame including a head portion and a grip portion, and optionally a shaft portion which connects the grip portion and the head portion, wherein the ball game racket frame is at least partially made of at least one layer of a plurality of fibers which are randomly orientated within the layer, wherein the plurality of fibers are preferably intertwined within the layer.

The ball game racket frame according to aspect 1, wherein the layer of fibers, which are randomly orientated and intertwined within the layer, is configured as a fiber veil, preferably a carbon fiber veil and/or a glass fiber veil.

The ball game racket frame according to aspect 1 or 2, wherein the layer of fibers, which are randomly orientated and intertwined within the layer, is configured as a non-woven fabric material.

The ball game racket frame according to any of the preceding aspects, wherein the fibers, which are randomly orientated and intertwined within the layer, are looped, preferably randomly looped, in the layer of fibers.

The ball game racket frame according to any of the preceding aspects, wherein the fibers, which are randomly orientated and intertwined, are at least partially bonded together, preferably by one or more bonding materials which preferably include a thermoplastic material, a resin and/or a thermosetting material.

The ball game racket frame according to any of the preceding aspects, wherein the fibers, which are randomly orientated and intertwined, are at least partially embedded in at least one matrix in the layer of fibers.

The ball game racket frame according to any of the preceding aspects, wherein the fibers which are randomly orientated and intertwined, including any bonding material which may be provided to bond the fibers together, account for at least 20 wt %, preferably at least 30 wt %, more preferably at least 40 wt %, more preferably at least 50 wt %, most preferably at least 60 wt %, of a total weight of at least a segment of the ball game racket frame.

The ball game racket frame according to any of the preceding aspects, wherein the layer(s) of fibers which are randomly orientated and intertwined, including any bonding material which may be provided in the layer(s) to bond the fibers together, account for at least 20 vol %, preferably at least 30 vol %, more preferably at least 40 vol %, more preferably at least 50 vol %, most preferably at least 60 vol %, of a total volume of the ball game racket frame in at least one cross-section of the ball game racket frame.

The ball game racket frame according to any of the preceding aspects, wherein the fibers, which are randomly orientated and intertwined, include carbon fibers and/or glass fibers.

The ball game racket frame according to any of the preceding aspects, wherein the fibers, which are randomly orientated and intertwined, include recycled fibers, preferably recycled carbon fibers and/or recycled glass fibers.

The ball game racket frame according to aspect 10, wherein the recycled fibers account for at least 20 wt %, preferably at least 25 wt %, more preferably at least 30 wt %, more preferably at least 35 wt %, more preferably at least 40 wt %, more preferably at least 45 wt %, most preferably at least 50 wt %, of a total weight of all fibers included in the ball game racket frame.

The ball game racket frame according to any of the preceding aspects, wherein the fibers, which are randomly orientated and intertwined, have an average length of no more than 30 mm, preferably no more than 25 mm, more preferably no more 20 mm, more preferably no more than 15 mm, preferably no more than 12 mm, more preferably no more than 10 mm, more preferably no more than 8 mm, more preferably no more than 6 mm, most preferably no more than 4 mm.

The ball game racket frame according to any of the preceding aspects, wherein each fiber of the fibers, which are randomly orientated and intertwined, has a length of no more than 30 mm, preferably no more than 25 mm, more preferably no more than 20 mm, more preferably no more than 15 mm, preferably no more than 12 mm, more preferably no more than 10 mm, more preferably no more than 8 mm, more preferably no more than 6 mm, most preferably no more than 4 mm.

The ball game racket frame according to any of the preceding aspects, wherein the ball game racket frame is at least partially made of at least one layer of a plurality of substantially unidirectionally orientated fibers in at least one or more sections of the ball game racket frame.

The ball game racket frame according to any of the preceding aspects, wherein the layer of fibers, which are randomly orientated and intertwined, is embedded between layers of prepregs of a composite material, the composite material preferably including a plurality of carbon fibers and/or a plurality of glass fibers.

The ball game racket frame according to any of the preceding aspects, wherein the ball game racket frame is at least partially made of:

    • a plurality of fibers which are braided;
    • and/or
    • a plurality of fibers which are woven.

The ball game racket frame according to any of the preceding aspects, wherein the layer of fibers, which are randomly orientated and intertwined, has a ratio of a strength or a stiffness of the layer of fibers in a first direction to a strength or a stiffness of the layer of fibers in a second direction of no more than 12, more preferably no more than 11.5, more preferably no more than 11, more preferably no more than 10.5, more preferably no more than 10, more preferably no more than 9.5, more preferably no more than 9, more preferably no more than 8.5, more preferably no more than 8, more preferably no more than 7.5, more preferably no more than 7, more preferably no more than 6.5, more preferably no more than 6, more preferably no more than 5.5, more preferably no more than 5, more preferably no more than 4.5, more preferably no more than 4, more preferably no more than 3.5, more preferably no more than 3, preferably no more than 2.5, more preferably no more than 2, more preferably no more than 1.8, more preferably no more than 1.6, most preferably no more than 1.4, the first direction extending substantially perpendicularly to the second direction and the first direction and the second direction preferably lying in a single plane.

The ball game racket frame according to any of the preceding aspects, wherein the layer of fibers, which are randomly orientated and intertwined, has a ratio of a strength or a stiffness of the layer of fibers in a first direction to a strength or a stiffness of the layer of fibers in a second direction from 1.4 to 12, more preferably from 1.4 to 9, more preferably from 1.4 to 6, more preferably from 1.4 to 3, the first direction extending substantially perpendicularly to the second direction and the first direction and the second direction preferably lying in a single plane.

The ball game racket frame according to any of the preceding aspects, wherein the head portion, the shaft portion and/or the grip portion include(s) at least one layer of the of at least one layer of a plurality of fibers which are randomly orientated and intertwined.

The ball game racket frame according to any of the preceding aspects, wherein the ball game racket frame includes a plurality of layers of the at least one layer of fibers, which are randomly orientated and intertwined, and a plurality of layers of fiber-reinforced prepregs, wherein the plurality of layers of fibers, which are randomly orientated and intertwined, and the plurality of layers of fiber-reinforced prepregs are stacked intermittently in at least a section of the ball game racket frame.

The ball game racket frame according to any of the preceding aspects, wherein the layer of fibers which are randomly orientated and intertwined, including any bonding material which may be provided to bond the fibers together, has an area weight of 20 to 150 g/m2, preferably an area weight of at least 20 g/m2, more preferably an area weight of at least 30 g/m2, more preferably an area weight of at least 40 g/m2, more preferably an area weight of at least 50 g/m2, more preferably an area weight of at least 60 g/m2, more preferably an area weight of at least 70 g/m2, more preferably an area weight of at least 80 g/m2, more preferably an area weight of at least 90 g/m2, more preferably an area weight of at least 100 g/m2, more preferably an area weight of at least 110 g/m2, more preferably an area weight of at least 120 g/m2, more preferably an area weight of at least 130 g/m2, more preferably an area weight of at least 140 g/m2, most preferably an area weight of at least 150 g/m 2.

The ball game racket frame according to any of the preceding aspects, wherein at least one cross-section of the ball game racket frame, preferably at least one cross-section of the head portion, includes at least two layers of the fibers which are randomly orientated and intertwined, wherein a first layer of the at least two layers, which is arranged further from a center of the cross-section than a second layer of the at least two layers, has a greater thickness than the second layer.

The ball game racket frame according to any of the preceding aspects, wherein, at least in a section of the ball game racket frame, the layer of fibers, which are randomly orientated and intertwined, has an average ratio of a length of the fibers in a fiber extension direction to a total length of the layer of fibers in the fiber extension direction of no more than 0.5, preferably no more than 0.4, more preferably no more than 0.3.

The ball game racket frame according to any of the preceding aspects, wherein the fibers which are randomly orientated and intertwined account for at least 20 wt %, more preferably at least 30 wt %, more preferably at least 40 wt %, more preferably at least 50 wt %, most preferably at least 60 wt %, of a total weight of at least a segment of the ball game racket frame.

The ball game racket frame according to any of the preceding aspects, wherein the fibers which are randomly orientated and intertwined account for at least 20 vol %, more preferably at least 30 vol %, more preferably at least 40 vol %, more preferably at least 50 vol %, most preferably at least 60 vol %, of a total volume of the ball game racket frame in at least one cross-section of the ball game racket frame.

The ball game racket frame according to any of the preceding aspects, wherein a proportion of the fibers which are randomly orientated and intertwined and which have a length of no more than 30 mm, more preferably no more than 25 mm, more preferably no more than 20 mm, more preferably no more than 15 mm, account for at least 20 wt %, more preferably at least 30 wt %, more preferably at least 40 wt %, more preferably at least 50 wt %, most preferably at least 60 wt %, of a total weight of at least a segment of the ball game racket frame.

A ball game racket including the ball game racket frame according to any of the preceding aspects and at least one striking surface for striking a game ball.

A method for manufacturing a ball game racket frame, preferably the ball game racket frame according to any of aspects 1 to 26, including the following steps:

    • a) providing at least one layer of a plurality of fibers which are randomly orientated, and preferably intertwined, within the layer;
    • b) forming the ball game racket frame at least partially from the at least one layer of fibers.

The method according to aspect 28, wherein the method further includes the steps of providing at least one layer of a fiber-reinforced prepreg and forming the ball game racket frame at least partially from the at least one layer of fiber-reinforced prepreg.

The method according to aspect 29, wherein the ball game racket frame is formed at least partially from a plurality of layers of fibers, which are randomly orientated and intertwined, and a plurality of layers of a fiber-reinforced prepreg, wherein the plurality of layers of fibers, which are randomly orientated and intertwined, and the plurality of layers of a fiber-reinforced prepreg are stacked intermittently in at least a section of the ball game racket.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention are further elucidated below with reference to the figures. The described embodiments do not limit the present invention.

FIG. 1 shows, in a schematic front view, a ball game racket frame according to an embodiment of the invention;

FIG. 2 shows, in a schematic enlarged cross-sectional view, a configuration of a cross-section of the ball game racket shown in FIG. 1 according to an embodiment of the invention;

FIG. 3 shows, in a schematic enlarged cross-sectional view, a configuration of a cross-section of the ball game racket shown in FIG. 1 according to an embodiment of the invention;

FIG. 4 shows, in a schematic front view, a layer of fibers which are randomly orientated and intertwined within the layer before the layer is applied to a ball game racket frame;

FIG. 5 shows, in a schematic front view, a ball game racket including a ball game racket frame according to a further embodiment of the invention;

FIG. 6 shows, in a schematic cross-sectional view, the ball game racket shown in FIG. 5 according to an embodiment of the invention;

 DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a ball game racket 10. In mere exemplary manner, the ball game racket 10 is illustrated as a tennis racket. However, the ball game racket 10 may also be any other ball game racket used for striking a ball or other object, such as a shuttlecock, in a leisure activity and/or a sports activity. For instance, the ball game racket 10 may be a badminton racket, a squash racket, or a paddle, such as for use in paddle ball, as shown in exemplary manner in FIGS. 5 and 6, or table tennis, or any other racket used in any other known racket sport.

The ball game racket 10 includes a ball game racket frame 12 having a head portion 14, a shaft portion 18 and a grip portion 20. As illustrated in FIG. 1, the ball game racket frame 12 may also include a throat portion 16 extending from the shaft portion 18 to the head portion 14.

The throat portion 16 may be open, in which case the throat portion 16 includes an opening 22, as illustrated in FIG. 1. Alternatively, the throat portion 16 may be closed, in which case the throat portion 16 does not include an opening. The throat portion 16 essentially serves the purpose of splitting the shaft portion 18 into two sections to extend around a circumference of the head portion 14. The throat portion 16 may also be omitted. In this case, the shaft portion 14 may be attached directly to the head portion 14.

The grip portion 20 may be configured to be gripped by a user, preferably by a user's hand, either by one hand or both hands of the user. For this purpose, the grip portion 20 may include features which may facilitate gripping thereof, such as suitable dimensions and/or a suitable shape and/or features which may increase the friction between the user's body, e.g., the user's palm, and the grip portion 20. The grip portion 20 may include a soft material, e.g., softer than the material of the shaft portion 18 and/or the head portion 14, to provide a comfortable grip for the user. The grip portion 20 extends along a longitudinal axis to the shaft portion 18.

The head portion 14 may comprise an opening 24 defined by a peripheral section 26 of the head portion 14, as shown in FIG. 1. The peripheral section 26 may be configured in a substantially oval shape, as shown in FIG. 1. Alternatively, the peripheral section 26 may be formed in any other shape, e.g., circular, rectangular, triangular, etc.

A string bed plane comprising a plurality of strings may be provided (not shown) and attached to at least a portion of the peripheral section 26 and extending across at least a portion of the opening 24. Such a string bed plane may provide a striking surface for striking a ball during use in a ball game sport and/or leisure activity.

Alternatively, the opening 24 may be omitted in the head portion 14. In this case, the head portion 14 may have a solid surface, which is preferably continuous and uninterrupted at least section-wise, instead of a string bed plane, which may provide the striking surface for striking a ball during use in a ball game sport and/or activity, as shown in FIG. 5. In such a configuration, the ball game racket 10 may be referred to as a paddle. Such a striking surface may also have at least one opening formed therein, the opening preferably being smaller than the size of the ball to be struck during use of the corresponding ball game racket in a respective ball game sport and/or activity (see FIG. 5 and the corresponding description further below).

The ball game racket frame 12 may be at least partially made of at least one layer of a plurality of fibers which are randomly orientated and intertwined within the layer. In particular, the layer of fibers, which are randomly orientated and intertwined within the layer, may be configured as a fiber veil, preferably a carbon fiber veil and/or a glass fiber veil.

Providing the ball game racket frame 12 with one or more layers of fibers which are randomly orientated and intertwined within the layer may improve the degree of dampening and/or the shock absorption properties of the ball game racket frame 12, in particular compared with ball game rackets which only include one or more layers of unidirectionally orientated fibers.

Furthermore, the randomly orientated and intertwined fibers may also improve the deformability and/or the handleability of the material, i.e., the at least one layer of a plurality of randomly orientated and intertwined fibers, e.g., the drapability of the material, during manufacturing and/or prior to manufacturing the ball game racket frame 12. For instance, improving the drapability of the material may allow to achieve smaller radii in at least sections of the ball game racket frame 12 and/or may facilitate providing smaller radii in at least sections of the ball game racket frame 12.

Moreover, providing at least one layer of a plurality of fibers which are randomly orientated and intertwined within the layer may reduce and/or limit a degree of orthotropy of the layer of fibers, more specifically of the ball game racket frame 12, and/or may increase a degree of isotropy of the layer of fibers, more specifically of the ball game racket frame 12, in at least a section of thereof. This may provide a more balanced ball game racket, e.g., compared with ball game rackets which only include layers of composite material having unidirectionally orientated fibers.

As shown in FIG. 1, a portion of the peripheral section 26 of the head portion 14 is cut along a cutting line 29, which is substantially perpendicular to the direction in which the peripheral section 26 extends around the opening 24. The cutting line 29 is illustrated as a dashed line to show an imaginary cut along said cutting line 29.

Based on the resulting cross-section 28 across a portion of the peripheral section 26 of the ball game racket frame 12 along line 29, a proportion, i.e., a percentage, e.g., a wt % and/or a vol %, of the fibers which are randomly orientated and intertwined, optionally including any bonding material which may be provided to bond the fibers together, of a total weight and/or a total volume, respectively, of at least a segment of the ball game racket frame, in particular at the respective cross-section 28, may be determined at the cross-section 28.

A plurality of cross-sections 28a, 28b, 28c, 28d, and 28e along several portions of the ball game racket frame 12 along a plurality of respective lines 29a, 29b, 29c, 29d, and 29e may be made to determine the proportion, i.e., a percentage, e.g., a wt % and/or a vol %, of the fibers which are randomly orientated and intertwined, optionally including any bonding material which may be provided to bond the fibers together, with respect to a total weight and/or a total volume, respectively, of at least a segment of the ball game racket frame, in particular at the respective cross-section 28, along the respective cross-section 28.

Thus, at least one cross-section, preferably a plurality of cross-sections, may be made in each of the head portion 14 and/or the shaft portion 18 and/or grip portion 20. For instance, a cross-section 28b, 28c, 28d, 28e along a portion of the grip portion 20 and/or the shaft portion 18, respectively, may have a first proportion, i.e., percentage, of fibers which are randomly orientated and intertwined, optionally including any bonding material which may be provided to bond the fibers together, with respect to a total weight and/or a total volume in the grip portion 20 and/or the shaft portion 18, respectively.

The shapes of the cross-sections 28, 28a, 28b, 28c, 28d, and 28e shown in FIG. 1 are for exemplary illustrative purposes only and do not necessarily reflect the actual cross-sections of the ball game racket frame 12 at the respective cross-section 28, 28a, 28b, 28c, 28d, and 28e. In fact, the ball game racket frame 12 may have any cross-sectional shape, e.g., circular, rectangular, or polygonal.

Preferably, the head portion 14, the shaft portion 18 and/or the grip portion 20 include(s) at least one layer of the at least one layer of a plurality of fibers which are randomly orientated and intertwined. This may provide an increased degree of dampening and/or shock absorption of the ball game racket frame in the respective portion(s) of the ball game racket frame 12 by improving a distribution of forces and/or moments and/or by at least partially interrupting a transfer of forces and/or moments in the head portion 14, the shaft portion 18 and/or the grip portion 20. Selectively providing the layer(s) of fibers which are randomly orientated and intertwined in one or more certain portions of the ball game racket frame 12 may allow the ball game racket frame 12 to be fine-tuned and/or tailored to the respective user's desires and/or needs, e.g., to the respective user's style of play and/or experience.

For instance, providing at least one layer of the of at least one layer of a plurality of fibers which are randomly orientated and intertwined at least in the head portion 14 may be advantageous to the impact characteristics of the ball game racket. In particular, as discussed above, a string bed plane comprising a plurality of strings may be attached to at least a portion of the peripheral section 26 of the head portion 14. Such a string bed plane may provide a striking surface for striking a ball during use in a ball game sport and/or leisure activity. Thus, providing at least one layer of fibers which are randomly orientated and intertwined at least in the head portion 14 may be an efficient and/or effective means for absorbing at least a portion of forces and/or moments which may be exerted to the ball game racket via the string bed plane.

Exemplary cross-sections 28 are shown in FIGS. 2 and 3. In particular, FIGS. 2 and 3 show configurations of the cross-section 28a of the head portion 14.

As shown in FIGS. 2 and 3, the ball game racket frame 12 may include a tube 30, sometimes also referred to as a bladder, in particular with respect to tennis rackets. The tube 30 includes a hollow space 32 arranged within the tube 30. The tube 30 may be covered in one or more layers 34 of a plurality of fibers which are randomly orientated and intertwined within the respective layer 34. As mentioned above, the cross-sections of the ball game racket frame 12, e.g., the cross-section 28a of the head portion 14 shown in FIGS. 2 and 3, may have any cross-sectional shape, e.g., circular, rectangular, or polygonal. The cross-sectional shape of the cross-section 28a shown in FIGS. 2 and 3 is thus only exemplary and does not limit the cross-sections of the ball game racket frame 12 to such a shape. The same applies to the cross-sectional shape of the tube 30. In fact, the tube 30 may have any cross-sectional shape and is thus not limited to the cross-sectional shape shown in FIGS. 2 and 3.

As shown in FIG. 3, the tube 30 may be covered in one or more layers 34 of fibers which are randomly orientated and intertwined within the layer 34, and optionally one or more layers 36 of prepregs of a composite material, e.g., prepregs which include unidirectionally orientated fibers in each layer thereof. As shown in FIG. 3, the one or more layers 36 of prepreg may be arranged between the tube 30 and the one or more layers 34 of fibers which are randomly orientated and intertwined within the respective layer 34. Alternatively, the one or more layers 34 of fibers which are randomly orientated and intertwined within the layer 34 may be arranged between the tube 30 and the one or more layers 36 of prepreg. Further alternatively, the one or more layers of fibers, which are randomly orientated and intertwined, and the one or more layers of fiber-reinforced prepregs, e.g., prepregs which include unidirectionally orientated fibers in each layer thereof, may be stacked intermittently in at least a section of the ball game racket frame 12. Alternatively, or additionally, at least one layer of fibers, which are randomly orientated and intertwined, may be embedded between layers of prepregs of composite material which preferably include unidirectionally orientated fibers in each layer thereof.

FIG. 4 shows, in an exemplary manner, a layer 50 of fibers 52 which are randomly orientated and intertwined within the layer 50, such as the layer(s) 34 shown in FIGS. 2 and 3, before the layer 50 is applied to the ball game racket frame 12. The layer 50 may be configured as a fiber veil, preferably a carbon fiber veil and/or a glass fiber veil. Alternatively, the layer 50 may be configured as a non-woven fabric material.

The fibers 52 may be at least partially bonded together by at least one bonding material 54, preferably a thermoplastic material, e.g., a resin and/or a thermosetting material.

At least some of the fibers 52, which are randomly orientated and intertwined within the layer 50, may be looped, preferably randomly looped, in the layer 50 of fibers 52, as indicated, for instance, at 52a in FIG. 4.

FIG. 5 shows an exemplary embodiment of a ball game racket 110 which also includes a ball game racket frame 112 having a head portion 114, a shaft portion 118 and a grip portion 120. The head portion 114 defines at least one striking surface 121, which is preferably substantially planar surface, for striking a ball during use in a ball game sport and/or leisure activity. The striking surface 121 does not have to be substantially planar. Instead, the striking surface 121 may be curved and/or angled in sections thereof. Preferably, the ball game racket 110 has two striking surfaces 121 which are arranged on opposite sides of the ball game racket 110, as shown in FIG. 6.

As shown in FIG. 5, the striking surface 121 may be at least partially defined by a solid structure, which is preferably continuous and uninterrupted at least section-wise. The solid structure may be at least partially defined by a core (see FIG. 6 and the corresponding description below).

The solid structure may have one or more openings 124 formed therein, preferably one or more through-holes which extend completely through the head portion 114, preferably substantially perpendicular to at least one of the striking surfaces 121. Alternatively, or additionally, a string bed plane comprising a plurality of strings, which are attachable to at least a portion of the head portion 114, may be provided to define the striking surface(s). In particular, the ball game racket frame 10 shown in FIG. 1 may be suitable for having such a string bed plane comprising a plurality of strings which may provide at least one striking surface for striking a ball during use in a ball game sport and/or leisure activity, as discussed above.

The ball game racket 110 shown in FIG. 5 is a padel tennis racket. However, the configuration of the ball game racket 110 as a padel tennis racket is only an exemplary embodiment. The ball game racket 110 may be any ball game racket which has a striking surface 121 which is defined by a substantially solid structure, which is preferably continuous and uninterrupted at least section-wise, and optionally having one or more openings 124, as shown in FIG. 5, and which is used for striking a ball or other object in a leisure activity and/or a sports activity. Such a ball game racket 110, i.e., as shown in FIG. 5, may be referred to as a paddle.

The ball game racket 110 may further include an opening 126 provided in the shaft portion 118, the opening 126 preferably extending completely through the ball game racket 110, preferably substantially perpendicularly to the at least one of the striking surfaces 121.

FIG. 6 shows a cross-sectional view of the ball game racket 110 shown in FIG. 5 along the cutting along A-A which extends through a section of the head portion 114. As shown in FIG. 6, the ball game racket 110 may include a core 129 and one or more layers 130 of a plurality of fibers which are randomly orientated and intertwined within the layer 130, such as one or more of the layer 50 shown in FIG. 4. One or more layers 130 of a plurality of fibers which are randomly orientated and intertwined within the layer 130 may be attached on one side or each side of the ball game racket 110, as shown in FIG. 6. An outer layer of the one or more layers 130 may at least partially define at least one of the striking surfaces 121, as shown in FIG. 6. Alternatively, one or more coatings, e.g., one or more coatings made of polyamide (PA), polylactides (PLA), and Polyethylene terephthalate (PET), and/or a powder, and/or one or more further layers of material, such as one or more layers of a further composite material, which preferably include unidirectionally orientated fibers, may be arranged on an outer surface of the layer(s) 130 and may thus at least partially define the striking surface(s) 121.

The core 129 may be made of a solid material, e.g., foam. Alternatively, the core 129 may be omitted. For instance, the core 129 may be replaced by a composite material, e.g., one or more layers of a composite material which includes a plurality of fibers, e.g., the one or more layers 130 and/or one or more layers of a composite material which includes unidirectionally orientated fibers.

Alternatively, or additionally, to the layers 130 provided in the head portion 114, as shown in FIG. 6, the shaft portion 118 and/or the grip portion 120 may be provided with one or more of the layers 130 shown in FIG. 6.

Optionally, the ball game racket 110 may include one or more layers of prepregs of a composite material, e.g., prepregs which include unidirectionally orientated fibers in each layer thereof. The one or more layers of prepreg, which preferably include unidirectionally orientated fibers, may be arranged between the core 129 and the layers 130 of fibers which are randomly orientated and intertwined, respectively. Alternatively, the one or more layers of prepreg, which preferably include unidirectionally orientated fibers, may be arranged on a side of the layers 130 which is opposite of the core 129. of fibers which are randomly orientated and intertwined, respectively. Further alternatively, the one or more layers of fibers 130, which are randomly orientated and intertwined, and the one or more layers of fiber-reinforced prepregs, e.g., prepregs which include unidirectionally orientated fibers in each layer thereof, may be stacked intermittently in at least a section of the ball game racket 110.

Claims

1. A ball game racket frame including a head portion, a grip portion and a shaft portion which connects the grip portion and the head portion, wherein the ball game racket frame is at least partially made of at least one layer of a plurality of fibers configured as a fiber veil formed of a non-woven fabric material, wherein the fibers are randomly orientated and intertwined within the at least one layer, wherein the at least one layer is embedded between layers of prepregs of a composite material, and wherein the fiber veil is at least partially transparent or at least partially translucent before incorporation into the ball game racket frame.

2. (canceled)

3. (canceled)

4. The ball game racket frame according to claim 1, wherein the layer(s) of fibers which are randomly orientated and intertwined, including any bonding material which may be provided in the layer(s) to bond the fibers together, account for at least 20 vol % of a total volume of the ball game racket frame in at least one cross-section of the ball game racket frame.

5. The ball game racket frame according to claim 1, wherein the fibers, which are randomly orientated and intertwined, have an average length of no more than 30 mm.

6. The ball game racket frame according to claim 1, wherein each fiber of the fibers, which are randomly orientated and intertwined, has a length of no more than 30 mm.

7. The ball game racket frame according to claim 1, wherein the ball game racket frame is at least partially made of at least one layer of a plurality of substantially unidirectionally orientated fibers in at least one or more sections of the ball game racket frame.

8. (canceled)

9. The ball game racket frame according to claim 1, wherein the ball game racket frame is at least partially made of:

a plurality of fibers which are braided; and/or
a plurality of fibers which are woven.

10. The ball game racket frame according to claim 1, wherein the layer of fibers, which are randomly orientated and intertwined, has a ratio of a strength or a stiffness of the layer of fibers in a first direction to a strength or a stiffness of the layer of fibers in a second direction of no more than 12, the first direction extending substantially perpendicularly to the second direction.

11. The ball game racket frame according to claim 1, wherein the layer of fibers, which are randomly orientated and intertwined, has a ratio of a strength or a stiffness of the layer of fibers in a first direction to a strength or a stiffness of the layer of fibers in a second direction from 1.4 to 12, the first direction extending substantially perpendicularly to the second direction.

12. The ball game racket frame according to claim 1, wherein the ball game racket frame includes a plurality of layers of the at least one layer of fibers, which are randomly orientated and intertwined, and a plurality of layers of fiber-reinforced prepregs, wherein the plurality of layers of fibers, which are randomly orientated and intertwined, and the plurality of layers of fiber-reinforced prepregs are stacked intermittently in at least a section of the ball game racket frame.

13. The ball game racket frame according to claim 1, wherein the layer of fibers which are randomly orientated and intertwined, including any bonding material which may be provided to bond the fibers together, has an area weight of 20 to 150 g/m2.

14. The ball game racket frame according to claim 1, wherein at least one cross-section of the ball game racket frame includes at least two layers of the fibers which are randomly orientated and intertwined, wherein a first layer of the at least two layers, which is arranged further from a center of the cross-section than a second layer of the at least two layers, has a greater thickness than the second layer.

15. The ball game racket frame according to claim 1, wherein, at least in a section of the ball game racket frame, the layer of fibers, which are randomly orientated and intertwined, has an average ratio of a length of the fibers in a fiber extension direction to a total length of the layer of fibers in the fiber extension direction of no more than 0.5.

16. The ball game racket frame according to claim 1, wherein the fibers which are randomly orientated and intertwined account for at least 20 wt % of a total weight of at least a segment of the ball game racket frame.

17. The ball game racket frame according to claim 1, wherein the fibers which are randomly orientated and intertwined account for at least 20 vol % of a total volume of the ball game racket frame in at least one cross-section of the ball game racket frame.

18. The ball game racket frame according to claim 1, wherein a proportion of the fibers which are randomly orientated and intertwined and which have a length of no more than 30 mm account for at least 20 wt % of a total weight of at least a segment of the ball game racket frame.

19. A ball game racket including the ball game racket frame according to claim 1 and at least one striking surface for striking a game ball.

20. A method for manufacturing a ball game racket frame, including the following steps:

a) providing at least one layer of a plurality of fibers configured as a fiber veil formed of a non-woven fabric material, where the fibers are randomly orientated and intertwined within the at least one layer, wherein the at least one layer is embedded between layers of prepregs of a composite material, and wherein the fiber veil is at least partially transparent or at least partially translucent before incorporation into the ball game racket frame;
b) forming the ball game racket frame at least partially from the at least one layer of fibers.

21. The method of claim 20, further including:

c) providing at least one layer of a fiber-reinforced prepreg; wherein the ball game racket frame is formed at least partially from the at least one layer of fiber-reinforced prepreg.

22. A ball game racket frame including a head portion, a grip portion and a shaft portion which connects the grip portion and the head portion, wherein the ball game racket frame is at least partially made of at least one layer of a plurality of fibers configured as a fiber veil formed of a non-woven fabric material, wherein the fibers are randomly orientated and intertwined within the at least one layer, wherein the at least one layer is embedded between layers of prepregs of a composite material, and wherein the fiber veil is at least partially transparent or at least partially translucent.

23. The ball game racket frame of claim 22, wherein the layer(s) of fibers which are randomly orientated and intertwined, including any bonding material which may be provided in the layer(s) to bond the fibers together, account for at least 20 vol % of a total volume of the ball game racket frame in at least one cross-section of the ball game racket frame.

Patent History
Publication number: 20240058656
Type: Application
Filed: Aug 18, 2022
Publication Date: Feb 22, 2024
Applicant: Head Technology GMBH (Kennelbach)
Inventors: Herfried LAMMER (St. Veit an der Glan), Stefan MOHR (Dornbirn), Ralf SCHWENGER (Weiler-Simmerberg)
Application Number: 17/890,523
Classifications
International Classification: A63B 49/02 (20060101);