US20060199680A1 - Ball game racquet, especially tennis racquet - Google Patents

Ball game racquet, especially tennis racquet Download PDF

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Publication number
US20060199680A1
US20060199680A1 US11/267,575 US26757505A US2006199680A1 US 20060199680 A1 US20060199680 A1 US 20060199680A1 US 26757505 A US26757505 A US 26757505A US 2006199680 A1 US2006199680 A1 US 2006199680A1
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US
United States
Prior art keywords
racquet
spacing layer
prepreg
wall
layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US11/267,575
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English (en)
Inventor
Ralf Schwenger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Volkl Tennis GmbH
Original Assignee
Volkl Tennis GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Volkl Tennis GmbH filed Critical Volkl Tennis GmbH
Assigned to VOLKL TENNIS GMBH reassignment VOLKL TENNIS GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SCHWEGER RALF
Publication of US20060199680A1 publication Critical patent/US20060199680A1/en
Abandoned legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B60/00—Details or accessories of golf clubs, bats, rackets or the like

Definitions

  • the invention relates to a ball sport or ball game racquet, in particular a tennis racquet, with a racquet frame for holding the stringing and with a shaft extending from the racquet frame and with a racquet grip.
  • the racquet frame and the racquet shaft both feature a hollow frame profile made up of a plurality of walls or wall sections.
  • the invention also relates to a method for manufacturing a hollow frame profile for such a ball sport racquet.
  • Modern ball sport or ball game racquets in particular tennis racquets, consist among other things of a racquet frame and a racquet shaft extending from and connected with this racquet frame.
  • the racquet frame and the racquet shaft are manufactured from an outwardly closed hollow frame profile, which normally is made from a plurality of prepreg layers that are pressed together to form closed hollow frame profile.
  • Prepreg layers are layers of synthetic or plastic material reinforced by fibers, such as carbon fibers, glass fibers and also other fibers, which are pre-impregnated with resin.
  • Prepreg layers can be designed as woven prepreg layers, which are pre-impregnated in form of unidirectional and multi-axial layers.
  • various resins are used, especially epoxide or epoxy resins and phenolic resins, both of which hardly flow at room temperature.
  • the prepreg layers are placed in cold condition in a pre-defined mold and hardened under pressure and application of heat. Especially the application of heat causes the resin to liquefy temporarily so that it impregnates the fibers before it begins to harden.
  • blow molding methods for manufacturing a racquet frame and racquet shaft featuring a hollow frame profile with a pre-defined wall thickness and fiber orientation and a defined outer contour and surface.
  • a plurality of prepreg layers or prepreg layer windings are placed carefully and load-oriented on or around a core, which for example is covered with a tube, and pressed under high pressure into a female mold and hardened to achieve a defined surface and outer contour.
  • a core which for example is covered with a tube, and pressed under high pressure into a female mold and hardened to achieve a defined surface and outer contour.
  • the wall thicknesses and the outer diameters of the hollow frame profile have a significant influence on the playability of a tennis racquet, so that especially tennis racquets for amateur and hobby use have a very high and wide hollow frame profile with a wall thickness of less than 1 mm in order to achieve a very high degree of stiffness in combination with low weight (less than 200 g).
  • the hollow frame profile of the racquet frame and of the racquet shaft comprises for example four opposing walls in pairs, which can have one left and right opposing wall, each with a height of up to 30 mm or more and one upper and lower opposing wall, each with a width of up to 15 mm or more, to form a honeycomb cross section.
  • neither the upper and lower walls nor the left and right walls of the hollow frame profile are stiff; rather, they receive the necessary stiffness by suitably connecting the corresponding walls.
  • It is an object of the present invention is to provide for a ball sport racquet of the type mentioned at the outset featuring a sufficiently high degree of stiffness despite a high and wide hollow frame profile.
  • a ball sport or ball game racquet in particular tennis racquet, with a racquet frame for holding the stringing and with a shaft extending from the racquet frame and with a racquet grip, wherein the racquet frame and the racquet shaft both feature a hollow frame profile made up of a plurality of walls or wall sections, and wherein at least one of the walls of the racquet frame and/or of the racquet shaft features at least in some sections at least one spacing layer for increasing the stability of the ball sport racquet.
  • the increase of stability is not or only to a small extend obtained by the stability or strength of the material of the spacing layer itself, but mainly by the fact that prepreg layers or the windings of the wall or wall section are spaced from another by the spacing layer and that by that the moment of inertia of the wall and the stiffness the wall are increased without substantially increasing the weight of the ball sport racquet.
  • a spacing layer in at least one of the walls of the hollow frame profile of a ball sport racquet according to the invention, on at least one or more wall sections, significantly increases the stiffness of the overall racquet frame.
  • the spacing layer is provided in-between the wall layers forming the wall or wall section, that means in-between two windings in the shaft area and in the upper and lower wall sections of the hollow frame profile, if the hollow frame profile is made by winding the prepreg material around a core.
  • the spacing layer is manufactured from a porous or honeycomb material, which is for example known from airplane construction. Alternatively, various foam materials can be used for manufacturing the spacing layer, due to their low volume weight.
  • the density of the material used should be considerably below the density of the prepreg layers, which have a density of approx. 1.9 g/cm 3 .
  • the materials used preferably have a density of less than 1.0 g/cm 3 while also featuring a high degree of compressive strength. This is of particular importance, since when applying the blow molding method for manufacturing the hollow frame profile of the tennis racquet, pressures of more than 8 bar can occur, so that the material used as the spacing layer must be able to withstand such high pressures during the production process.
  • FIG. 1 shows a simplified representation in top view of a ball sport racquet in the form of a tennis racquet
  • FIG. 2 shows a simplified representation in cross section corresponding to the line 1 - 1 of FIG. 1 ;
  • FIG. 3 shows a simplified representation in cross section corresponding to the line 11 - 11 of FIG. 1 ;
  • FIG. 4 shows a simplified representation of shaft area of the ball sport racquet in the form of a tennis racquet
  • FIG. 5 shows a simplified representation of single selected production steps for a hollow frame profile manufactured according to the blow molding process.
  • the tennis racquet depicted in the drawings and generally designated 1 consists essentially of a racquet frame 2 forming the racquet head, of the stringing 3 located there, which comprises a plurality of crisscrossing string lengths 4 ′, 4 ′′ or strings 4 , and of a racquet shaft 6 connecting to the racquet frame 2 by means of a throat or heart 5 and on which (shaft) a racquet grip 7 is provided.
  • the throat 5 is connected with the racquet frame 2 in the connecting areas 5 ′, 5 ′′.
  • the racquet frame 2 features an outwardly closed hollow frame profile 8 , which is manufactured for example from a plurality of prepreg layers according to the blow molding process.
  • FIG. 2 shows a cross section corresponding to the line 1 - 1 of FIG. 1 .
  • the hollow frame profile 8 features by way of example an oval cross section flattened on two opposing sides each being at a distance form the stinging and parallel or nearly parallel with the stringing.
  • the hollow frame profile 8 features a hollow space 9 , which is surrounded by the walls of a plurality of prepreg layers or windings 10 .
  • the hollow frame profile 8 in the depicted embodiment consists of one upper and lower, opposing flat or nearly flat wall sections 8 . 1 , 8 . 2 and one left and right, likewise opposing wall sections 8 . 3 , 8 . 4 .
  • additional walls or wall sections can be provided for forming the hollow frame profile 8 .
  • the walls 8 . 1 and 8 . 2 are located on different sides of the strings 3 or stringing 4 , each with the greater distance from these strings.
  • the hollow frame profile 8 has for example a wall thickness W of approximately 1.0 mm.
  • the upper and lower wall sections 8 . 1 , 8 . 2 are parallel to each other in the depicted embodiment and are separated from each other by the hollow space 9 .
  • the left and right wall sections 8 are
  • FIG. 3 shows a cross section corresponding to the line 11 - 11 of FIG. 1 through one of the two hollow frame profiles 8 of the throat 5 .
  • the upper and lower wall sections 8 . 1 , 8 . 2 of the hollow frame profile 8 feature an upper and lower spacing layer 11 , 12 , which are embedded between one upper and lower prepreg winding layer 10 . 1 , 10 . 2 in the upper and lower wall sections 8 . 1 and 8 . 2 .
  • the spacing layer 11 , 12 is manufactured from a honeycomb material 11 . 1 , 12 . 1 , which is for example known from airplane construction. Alternatively, a foam material with a low volume weight can be used. In a preferred embodiment, the density of the material 11 . 1 , 12 . 1 is less than 1.0 g/cm 3 and therefore considerably less than the density of the prepreg layers 10 (approx. 1.9 g/cm 3 ). In addition, the material 11 . 1 , 12 . 1 of the spacing layers 11 , 12 has a compressive strength greater than 8.0 ⁇ 10 5 N/m 2 in order to be able to withstand the pressures of more than 8 bar occurring during the production process when the blow molding process is used to manufacture the hollow frame profile 8 .
  • FIG. 4 shows the shaft area of the tennis racquet 1 , in particular the throat 5 with one first and second hollow frame profile 8 a , 8 b , both of which are connected via the racquet shaft 6 .
  • the figure depicts a spacing layer 11 extending over the depicted hollow frame profile 8 a , 8 b and possessing the same curvature and which is inserted during the manufacturing process for the tennis racquet 1 for example into the upper wall section 8 . 1 of the second hollow frame profile 8 b to increase the stiffness of the tennis racquet 1 , particularly in the shaft area.
  • the insertion point of the spacing layer 11 in the throat 5 of the shaft area of the tennis racquet 1 is indicated by two arrows, which point to the upper wall section 8 . 1 of the second hollow frame profile 8 b.
  • the racquet shaft 6 also features a hollow frame profile 13 , which consists of upper and lower walls or wall sections 13 . 1 , 13 . 2 and left and right walls or wall sections 13 . 3 , 13 . 4 . Furthermore, the hollow frame profile 13 of the racquet shaft 6 also features one first and second connecting section 14 , 15 , by means of which the first and second hollow frame profile 8 a , 8 b of the throat 5 are connected with the racquet shaft 6 .
  • the first and second connection sections 14 , 15 are provided on the end of the racquet shaft 6 facing the racquet head and are connected with each other by means of a preferably semi-circular connecting element 16 , which closes the hollow space 17 of the hollow frame profile 13 of the racquet shaft 6 toward the outside.
  • the spacing layer 11 is inserted into the upper wall section 6 . 1 of the hollow frame profile 8 a of the throat 5 so that it projects at least partially over the second connecting section 15 into the racquet shaft 6 and therefore is integrated into the upper wall section 13 . 1 of the hollow frame profile 13 of the racquet shaft 6 .
  • a plurality of first and second spacing layers 11 , 12 can be provide both in the upper and in the lower wall sections 6 . 1 , 6 . 2 of the hollow frame profile 8 a , 8 b or 13 . 1 , 13 . 2 , said spacing layers being brought together or located parallel to each other in the shaft area and in particular below the connecting element 16 .
  • the spacing layers 11 , 12 can also be provided in different sections of the hollow frame profile 8 of the racquet frame 6 ; in particular, the spacing layers 11 , 12 can extend either individually or in pairs over the connecting areas 5 ′- 5 ′′ between the throat 5 and the racquet frame 2 . Also, the alternating integration of the spacing layers 11 , 12 in sections of the upper and/or lower wall sections 8 . 1 , 8 . 2 or 13 . 1 , 13 . 2 of the tennis racquet 1 is possible.
  • FIG. 5 shows by way of example a simplified depiction of the hollow frame profile 8 in various stages of production during the manufacture of the hollow frame profile 8 according to the blow molding process.
  • a first production step (a) the prepreg layers 10 are oriented carefully according to the load and then placed by winding on a core (not depicted in FIG. 5 ) covered with a hose. This forms at least one first prepreg layer 10 . 1 for achieving the upper and lower as well as left and right wall sections 8 . 1 through 8 . 4 .
  • a second production step (b) one first and second spacing layer 11 , 12 made of the material 11 . 1 , 12 . 1 described above are placed on the at least first prepreg layer 10 . 1 in the upper and lower wall area and surrounded with at least one second prepreg winding or layer 10 . 2 .
  • the spacing layers 11 , 12 of the hollow frame profile 8 that are already surrounded by a plurality of further prepreg layers 10 are shown in a further production step (c) in FIG. 5 .
  • the prepreg layers 10 including the spacing layers 11 , 12 are pressed to the hollow frame profile 8 according to FIG. 3 under application of heat.
  • the application of heat causes the resin provided in the prepreg layers 10 to liquefy, bonding the synthetic layers and the spacing layers 11 , 12 embedded therein, which then are compressed to a stiff hollow frame profile 8 , 8 a , 8 b in the pressing process.
  • the hollow frame profile 8 , 8 a , 8 b created by the heating and pressing process is shown in FIG. 5 in a fourth production step (d).
US11/267,575 2004-11-10 2005-11-04 Ball game racquet, especially tennis racquet Abandoned US20060199680A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102004054190A DE102004054190B3 (de) 2004-11-10 2004-11-10 Ballspielschläger, insbesondere Tennisschläger
DE102004054190.6 2004-11-10

Publications (1)

Publication Number Publication Date
US20060199680A1 true US20060199680A1 (en) 2006-09-07

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US11/267,575 Abandoned US20060199680A1 (en) 2004-11-10 2005-11-04 Ball game racquet, especially tennis racquet

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US (1) US20060199680A1 (de)
DE (1) DE102004054190B3 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140100063A1 (en) * 2012-10-04 2014-04-10 Babolat Vs Badminton racket

Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3949988A (en) * 1972-06-08 1976-04-13 Fischer Gesellschaft M.B.H. Racket
US4042238A (en) * 1975-01-27 1977-08-16 Composite Structures Corporation Racket
US4357013A (en) * 1981-07-31 1982-11-02 David Fernandez Reinforced foam core composite structure and method
US5029858A (en) * 1990-07-17 1991-07-09 Dennis Chen Structure of a composite fiber racket
US5122405A (en) * 1990-12-11 1992-06-16 Supracor Systems, Inc. Shock absorbing means for sporting equipment handles
US5314180A (en) * 1989-08-28 1994-05-24 Toray Industries, Inc. Sports instrument and impact-absorbing element to be attached to sports equipment
US5358261A (en) * 1993-12-16 1994-10-25 Cheng Chin Cheng Metal racket frame
US5482774A (en) * 1989-11-28 1996-01-09 Sumitomo Rubber Industries, Ltd. Composite prepeg and tennis rackets using the same
US5642881A (en) * 1996-02-02 1997-07-01 Lisco, Inc. Tri-hollow racket with traverse ribs
US5928090A (en) * 1997-09-09 1999-07-27 Cabales; Raymund S. Golf shaft for controlling passive vibrations
US6012996A (en) * 1998-03-05 2000-01-11 Shenly Won Sport Co., Ltd. Game racket frame made of fiber reinforced plastic
US6592475B2 (en) * 2000-10-17 2003-07-15 Babolat Vs Sports racket having a tubular frame with reinforcing element
US20030224865A1 (en) * 2002-05-29 2003-12-04 Lai Chien Hao Tubular sport items
US20040138015A1 (en) * 2003-01-09 2004-07-15 Kuo-Pin Yu Racket frame
US6966855B2 (en) * 2003-07-01 2005-11-22 Kuo-Pin Yu Racket with capability of vibration absorption

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2522857A1 (de) * 1975-05-23 1976-12-09 Glaser Dirks Flugzeugbau Gmbh Tennisschlaeger
DE8607726U1 (de) * 1986-03-20 1986-09-04 Julius & August Erbslöh GmbH & Co, 5620 Velbert Tennisschläger
CA2216508A1 (en) * 1997-02-13 1998-08-13 Lisco, Inc. Sporting equipment constructed with composite materials having composite rods interspersed with bias plies

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3949988A (en) * 1972-06-08 1976-04-13 Fischer Gesellschaft M.B.H. Racket
US4042238A (en) * 1975-01-27 1977-08-16 Composite Structures Corporation Racket
US4357013A (en) * 1981-07-31 1982-11-02 David Fernandez Reinforced foam core composite structure and method
US5314180A (en) * 1989-08-28 1994-05-24 Toray Industries, Inc. Sports instrument and impact-absorbing element to be attached to sports equipment
US5482774A (en) * 1989-11-28 1996-01-09 Sumitomo Rubber Industries, Ltd. Composite prepeg and tennis rackets using the same
US5029858A (en) * 1990-07-17 1991-07-09 Dennis Chen Structure of a composite fiber racket
US5122405A (en) * 1990-12-11 1992-06-16 Supracor Systems, Inc. Shock absorbing means for sporting equipment handles
US5358261A (en) * 1993-12-16 1994-10-25 Cheng Chin Cheng Metal racket frame
US5642881A (en) * 1996-02-02 1997-07-01 Lisco, Inc. Tri-hollow racket with traverse ribs
US5928090A (en) * 1997-09-09 1999-07-27 Cabales; Raymund S. Golf shaft for controlling passive vibrations
US6012996A (en) * 1998-03-05 2000-01-11 Shenly Won Sport Co., Ltd. Game racket frame made of fiber reinforced plastic
US6592475B2 (en) * 2000-10-17 2003-07-15 Babolat Vs Sports racket having a tubular frame with reinforcing element
US20030224865A1 (en) * 2002-05-29 2003-12-04 Lai Chien Hao Tubular sport items
US20040138015A1 (en) * 2003-01-09 2004-07-15 Kuo-Pin Yu Racket frame
US6966855B2 (en) * 2003-07-01 2005-11-22 Kuo-Pin Yu Racket with capability of vibration absorption

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140100063A1 (en) * 2012-10-04 2014-04-10 Babolat Vs Badminton racket
US9227113B2 (en) * 2012-10-04 2016-01-05 Babolat Vs Badminton racket
EP2716333B1 (de) * 2012-10-04 2018-04-18 Babolat Vs Federballschläger

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AS Assignment

Owner name: VOLKL TENNIS GMBH, SWITZERLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SCHWEGER RALF;REEL/FRAME:017124/0852

Effective date: 20051112

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION