EP0555666B1 - Method of manufacture of a tennis racket frame - Google Patents

Method of manufacture of a tennis racket frame Download PDF

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Publication number
EP0555666B1
EP0555666B1 EP93100859A EP93100859A EP0555666B1 EP 0555666 B1 EP0555666 B1 EP 0555666B1 EP 93100859 A EP93100859 A EP 93100859A EP 93100859 A EP93100859 A EP 93100859A EP 0555666 B1 EP0555666 B1 EP 0555666B1
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EP
European Patent Office
Prior art keywords
bridge
thermoplastic
frame
hybrid yarn
process according
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Expired - Lifetime
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EP93100859A
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German (de)
French (fr)
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EP0555666A1 (en
Inventor
Giorgio Dr. Greening
Philippe Saguet
Regina Laws
Peter Dr. Ittemann
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Cytec Technology Corp
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Cytec Technology Corp
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    • 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
    • A63B49/03—Frames characterised by throat sections, i.e. sections or elements between the head and the shaft
    • 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
    • A63B60/06—Handles
    • A63B60/08—Handles characterised by the material
    • 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
    • A63B49/10—Frames made of non-metallic materials, other than wood
    • 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
    • A63B49/10—Frames made of non-metallic materials, other than wood
    • A63B49/11—Frames made of non-metallic materials, other than wood with inflatable tubes, e.g. inflatable during fabrication
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2209/00—Characteristics of used materials
    • A63B2209/02—Characteristics of used materials with reinforcing fibres, e.g. carbon, polyamide fibres
    • A63B2209/023—Long, oriented fibres, e.g. wound filaments, woven fabrics, mats

Definitions

  • the invention relates to a method for producing a tennis racket frame from tubular fiber composite material based on thermoplastic fiber / carbon fiber hybrid yarn.
  • Hybrid yarns in which thermoplastic fibers and reinforcing fibers are intimately mixed, have been increasingly used in the past few years for the production of high-performance composite materials.
  • the hybrid yarns as well as fabrics made therefrom, e.g. Braids are very flexible and can therefore be deformed as required. If they are consolidated by pressing at temperatures above the softening point of the thermoplastic, it melts and forms a matrix in which the reinforcing fibers are embedded in the preferred direction.
  • Tennis racket frames are also made from such hybrid yarn braids.
  • the starting point is a tubular braid into which an inflatable tube is inserted.
  • the braid is folded in the form of a tennis racket.
  • This structure is placed in a metal mold, the tube is inflated, and the tool is heated so that the braid is consolidated into a fiber-reinforced tube.
  • a tennis racket which is constructed from a frame and from a web.
  • the frame consists of a plastic tube that is reinforced with carbon fibers.
  • the web is tubular and is foamed with a thermoplastic material. Both elements are first prefabricated separately and then joined in a subsequent work step in such a way that they create a material connection.
  • EP-A 0 411 437 discloses a process for producing expandable granules and foams therefrom. These plastics are made using a blowing agent. For this purpose, the blowing agent and the granulated plastic material are mixed in an extruder. The resulting material is cooled to avoid uncontrolled expansion.
  • the invention was therefore based on the object of finding a better solution to the problem mentioned.
  • Figure 1 shows a sketch of the finished tennis racket frame, with (1) the handle, (2) the two legs and (3) the bridge.
  • Hybrid yarn made of carbon fibers and thermoplastic fibers as well as a preferred process for its production and processing into composite materials are described in EP-B 0 156 599. It is also mentioned there that the hybrid yarn can be used to produce fabrics which can be processed into composite bodies.
  • thermoplastics for the thermoplastic fibers are, for example, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyphenyl sulfide, polysulfones, polyether sulfones and polyether ketones; polyamides, such as polyamide-6 and polyamide-6,6, are particularly suitable.
  • thermoplastic materials for the plastic foam can in principle be the same thermoplastics as those from which the fibers are made.
  • the softening points should be of the same order of magnitude or slightly lower.
  • the thermoplastics should be selected so that the softening temperature of the thermoplastic plastic containing blowing agent is somewhat lower than the temperature at which the hybrid yarn is consolidated.
  • Polyamides, polyesters and polyetherimides as well as polysulfones and polyether sulfones are preferred.
  • the granules or the strand of thermoplastic plastic containing blowing agent can, e.g. described in DE-A 39 25 740, can be produced by extruding granules containing blowing agent.
  • Low-boiling liquids which preferably do not dissolve the thermoplastic, but at most swell, are preferred as blowing agents, preferably in amounts of 1 to 20, in particular 2 to 10,% by weight.
  • Suitable blowing agents are e.g. halogenated hydrocarbons such as dichloromethane and chlorobenzene, ketones such as acetone and methyl ethyl ketone, ethers, alcohols, water and mixtures thereof.
  • chemical blowing agents such as azo compounds and carbonates can also be used.
  • a tubular braid is first formed from the hybrid yarn.
  • the diameter of the cane depends on how thick the frame should be at each point; the tube is generally thicker on the handle than on the oval ring.
  • the wall thickness of the braid is on the order of 1 to 2 mm.
  • a flexible, thin-walled (0.05 to 2.0 mm) inflatable tube preferably made of a rubber or a high-melting plastic film, is then inserted into the tubular braid, after which the tubular braid is folded together in the form of a tennis racket frame.
  • a tubular hybrid yarn braid is again formed, which is approximately the length of the future bridge and has two tongue-shaped segments at each end.
  • Thermoplastic granulate or thermoplastic strand containing blowing agent is introduced into this mesh, expediently in a flat, flexible, thin-walled hose, preferably made of the same thermoplastic material as the thermoplastic fibers or a higher melting plastic.
  • the amount of granules filled in and the amount of blowing agent contained therein determine the density of the foam that forms when heated and the internal pressure that is to be built up in the process.
  • the density should be between 20 and 400 g / l, in particular between 50 and 200 g / l; the internal pressure in the order of 5 to 10 bar.
  • This piece of tubular hybrid braid is then placed as a bridge between the legs of the frame so that the two legs are encompassed by the tongue-shaped segments at the end of the braid. This state is shown in Figure 2.
  • the structure is then placed in a multi-part, preferably two-part metal mold, the inner surfaces of which correspond to the desired shape of the finished tennis racket frame.
  • the mold is closed and the tube is inflated to an internal pressure of the order of 5 to 10 bar, whereby the hybrid yarn braid is pressed against the mold wall.
  • the tool is then heated to a temperature above the melting point of the thermoplastic fibers and held at this temperature for about 3 to 30 minutes.
  • the tube can also be inflated simultaneously with or after the tool has been heated. If polyamide fibers are used, the tool temperature is around 300 ° C. The fibers fuse to form a consolidated plastic matrix in which the carbon fibers are embedded.
  • the two ends of the tube connect to form the handle of the racket, and the tongue-shaped segments of the bridge connect with the legs, so that the bridge is firmly integrated into the frame. If the mold temperature is sufficiently high, the thermoplastic granules also melt in the bridge, gaseous blowing agent is released and presses the walls of the braid forming the bridge firmly against the mold wall, so that this hybrid yarn braid is also consolidated. The tool is then cooled, the finished frame is demolded and, if necessary, reworked. The flexible hose can be pulled out or left in the frame.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Physical Education & Sports Medicine (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Pulmonology (AREA)
  • Laminated Bodies (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Moulding By Coating Moulds (AREA)
  • Molding Of Porous Articles (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

Abstract

The bridge (3) between the arms (2) of the grip (1) is also a tube of consolidated thermoplastic fibre/carbon fibre-hybrid yarn, which is filled with a foamed thermoplastic with a density between 20 and 400 g/l. The thermoplastic fibres comprise a polyamide and the plastic foam is a polyamide, a polysulphone or a polyether sulphone. To make the racquet frame, a tubular network of thermoplastic/carbon fibre/hybrid yarn is formed, into which is introduced a flexible, thin-walled, inflatable hose. The tubular network is formed into the shape of a racquet frame, and a piece of tubular hybrid yarn network is laid as bridge (3) between the arms (2) of the frame so that the two arms are encompassed by two tongue-shaped segments of the bridge. The frame is placed in a metal mould which is then closed. The hose is then inflated exerting a pressure on the hybrid yarn network which by subsequent heating is consolidated to form a fibre-reinforced tube.

Description

Die Erfindung betrifft ein Verfahren zur Herstellung eines Tennisschlägerrahmens aus rohrförmigem Faserverbundwerkstoff auf Basis von Thermoplastfaser/Kohlenstoffaser-Hybridgarn. Hybridgarne, in denen Thermoplastfasern und Verstärkungsfasern innig vermischt sind, werden in den letzten Jahren in zunehmendem Maße zur Herstellung von Hochleistungsverbundwerkstoffen verwendet. Die Hybridgarne sowie daraus hergestellte Flächengebilde, z.B. Geflechte, sind sehr flexibel und deshalb beliebig verformbar. Wenn man sie durch Verpressen bei Temperaturen oberhalb des Erweichungspunktes des Thermoplasten konsolidiert, schmilzt dieser und bildet eine Matrix, in der die Verstärkungsfasern in Vorzugsrichtung orientiert eingelagert sind.The invention relates to a method for producing a tennis racket frame from tubular fiber composite material based on thermoplastic fiber / carbon fiber hybrid yarn. Hybrid yarns, in which thermoplastic fibers and reinforcing fibers are intimately mixed, have been increasingly used in the past few years for the production of high-performance composite materials. The hybrid yarns as well as fabrics made therefrom, e.g. Braids are very flexible and can therefore be deformed as required. If they are consolidated by pressing at temperatures above the softening point of the thermoplastic, it melts and forms a matrix in which the reinforcing fibers are embedded in the preferred direction.

Aus derartigen Hybridgarngeflechten werden auch Tennisschlägerrahmen hergestellt. Man geht dabei von einem rohrförmigen Geflecht aus, in das man einen aufblasbaren Schlauch einführt. Das Geflecht wird in Form eines Tennisschlägers zusammengelegt. Dieses Gebilde wird in eine Metallform eingelegt, der Schlauch wird aufgeblasen, und das Werkzeug wird erhitzt, so daß das Geflecht zu einem faserverstärkten Rohr konsolidiert. Probleme bereitet dabei der Aufbau der "Brücke" zwischen den beiden Schenkeln des Griffes, welche zur Stabilisierung des Schlägers notwendig ist.Tennis racket frames are also made from such hybrid yarn braids. The starting point is a tubular braid into which an inflatable tube is inserted. The braid is folded in the form of a tennis racket. This structure is placed in a metal mold, the tube is inflated, and the tool is heated so that the braid is consolidated into a fiber-reinforced tube. The construction of the "bridge" between the two legs of the handle, which is necessary to stabilize the racket, presents problems.

Es ist nicht möglich, den aufblasbaren Schlauch, der im äußeren Rahmen des Tennisschlägers liegt, auch in die Brücke zu verlegen, um damit die Brücke an das Rohr, aus dem der Rahmen geformt wird, direkt anzubinden und beide gemeinsam unter Druck zu setzen. Man hat deshalb schon versucht, ein brückenförmiges Gebilde aus duroplastischem Polyurethanschaum mit Hybridgarngeflecht zu überziehen, dieses Gebilde zwischen die Schenkel des Rahmens einzulegen und zusammen mit dem Rahmen zu konsolidieren. Dabei entsteht aber kein genügender Innendruck in der Brücke, so daß hier das Hybridgarngeflecht nicht ausreichend konsolidiert wird. Dies führt zu porösen Schwachstellen, welche bei den hohen Torsions- und Zugbelastungen, welchen gerade die Brücke des Tennisschlägers ausgesetzt ist, Anlaß zu Bruch geben kann.It is not possible to lay the inflatable tube that is in the outer frame of the tennis racket in the bridge in order to directly connect the bridge to the tube from which the frame is formed and to pressurize both together. Attempts have therefore already been made to cover a bridge-shaped structure made of thermoset polyurethane foam with hybrid yarn braid, to insert this structure between the legs of the frame and to consolidate it together with the frame. However, there is no sufficient internal pressure in the bridge, so that the hybrid yarn braid is not sufficiently consolidated here. This leads to porous weak points, which are the high torsional and Tensile loads, which the tennis racket's bridge is exposed to, can give rise to breakage.

Aus der DE-A 22 07 802 ist ein Tennisschläger bekannt, der aus einem Rahmen und aus einem Steg aufgebaut ist. Der Rahmen besteht aus einem Kunststoffrohr, das mit aus Kohlenstoff bestehenden Fasern verstärkt ist. Der Steg ist rohrförmig ausgebildet und ist mit einem thermoplastischen Material ausgeschäumt. Beide Elemente werden zunächst getrennt vorgefertigt und in einem anschließenden Arbeitsgang derart zusammengefügt, daß sie eine stoffschlüssige Verbindung schaffen.From DE-A 22 07 802 a tennis racket is known which is constructed from a frame and from a web. The frame consists of a plastic tube that is reinforced with carbon fibers. The web is tubular and is foamed with a thermoplastic material. Both elements are first prefabricated separately and then joined in a subsequent work step in such a way that they create a material connection.

Die EP-A 0 411 437 offenbart ein Verfahren zur Herstellung von expandierbarem Granulat und Schaumstoffen daraus. Diese Kunststoffe werden durch Verwendung eines Treibmittels hergestellt. Dazu werden das Treibmittel und das granulierte Kunststoffmaterial in einem Extruder gemischt. Das resultierende Material wird gekühlt, um eine unkontrollierte Expansion zu vermeiden.EP-A 0 411 437 discloses a process for producing expandable granules and foams therefrom. These plastics are made using a blowing agent. For this purpose, the blowing agent and the granulated plastic material are mixed in an extruder. The resulting material is cooled to avoid uncontrolled expansion.

Der Erfindung lag also die Aufgabe zugrunde, eine bessere Lösung für das genannte Problem zu finden.The invention was therefore based on the object of finding a better solution to the problem mentioned.

Diese Aufgabe wird erfindungsgemäß durch das im Anspruch 1 gegebene Verfahren gelöst. Granulat oder einen Strang aus treibmittelhaltigem,This object is achieved by the method given in claim 1. Granules or a strand of blowing agent containing

Abbildung 1 zeigt eine Skizze des fertigen Tennisschlägerrahmens, wobei mit (1) der Griff, mit (2) die beiden Schenkel und mit (3) die Brücke bezeichnet sind.Figure 1 shows a sketch of the finished tennis racket frame, with (1) the handle, (2) the two legs and (3) the bridge.

Hybridgarn aus Kohlenstoffasern und Thermoplastfasern sowie ein bevorzugtes Verfahren zu seiner Herstellung und die Verarbeitung zu Verbundwerkstoffen sind in EP-B 0 156 599 beschrieben. Dort wird auch erwähnt, daß aus dem Hybridgarn Gewebe hergestellt werden kann, das man zu Verbundkörpern verarbeiten kann.Hybrid yarn made of carbon fibers and thermoplastic fibers as well as a preferred process for its production and processing into composite materials are described in EP-B 0 156 599. It is also mentioned there that the hybrid yarn can be used to produce fabrics which can be processed into composite bodies.

Bevorzugte thermoplastische Kunststoffe für die Thermoplastfasern sind z.B. Polypropylen, Polyethylenterephthalat, Polybutylenterephthalat, Polyphenylsulfid, Polysulfone, Polyethersulfone und Polyetherketone; besonders geeignet sind Polyamide, wie Polyamid-6 und Polyamid-6,6.Preferred thermoplastics for the thermoplastic fibers are, for example, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyphenyl sulfide, polysulfones, polyether sulfones and polyether ketones; polyamides, such as polyamide-6 and polyamide-6,6, are particularly suitable.

Die thermoplastischen Kunststoffe für den Kunststoffschaum können grundsätzlich die gleichen Thermoplasten sein, wie die, aus denen die Fasern bestehen. Die Erweichungspunkte sollen in der gleichen Größenordnung oder etwas niedriger liegen. Grundsätzlich sollen die Thermoplaste so gewählt werden, daß die Erweichungstemperatur des treibmittelhaltigen thermoplastischen Kunststoffs etwas niedriger liegt als die Temperatur, bei der das Hybridgarn konsolidiert wird. Bevorzugt sind Polyamide, Polyester und Polyetherimide sowie Polysulfone und Polyethersulfone.The thermoplastic materials for the plastic foam can in principle be the same thermoplastics as those from which the fibers are made. The softening points should be of the same order of magnitude or slightly lower. In principle, the thermoplastics should be selected so that the softening temperature of the thermoplastic plastic containing blowing agent is somewhat lower than the temperature at which the hybrid yarn is consolidated. Polyamides, polyesters and polyetherimides as well as polysulfones and polyether sulfones are preferred.

Das Granulat bzw. der Strang aus treibmittelhaltigem thermoplastischem Kunststoff kann, wie z.B. in DE-A 39 25 740 beschrieben, durch Extrudieren von treibmittelhaltigem Granulat hergestellt werden. Als Treibmittel kommen bevorzugt niedrig siedende Flüssigkeiten in Frage, die den Thermoplasten nicht lösen, sondern höchstens quellen, vorzugsweise in Mengen von 1 bis 20, insbesondere von 2 bis 10 Gew.-%. Geeignete Treibmittel sind z.B. halogenierte Kohlenwasserstoffe, wie Dichlormethan und Chlorbenzol, Ketone, wie Aceton und Methylethylketon, Ether, Alkohole, Wasser und Gemische davon. Grundsätzlich können auch chemische Treibmittel, wie Azoverbindungen und Carbonate verwendet werden.The granules or the strand of thermoplastic plastic containing blowing agent can, e.g. described in DE-A 39 25 740, can be produced by extruding granules containing blowing agent. Low-boiling liquids which preferably do not dissolve the thermoplastic, but at most swell, are preferred as blowing agents, preferably in amounts of 1 to 20, in particular 2 to 10,% by weight. Suitable blowing agents are e.g. halogenated hydrocarbons such as dichloromethane and chlorobenzene, ketones such as acetone and methyl ethyl ketone, ethers, alcohols, water and mixtures thereof. In principle, chemical blowing agents such as azo compounds and carbonates can also be used.

Zur Herstellung des erfindungsgemäßen Tennisschlägerrahmens wird zunächst ein rohrförmiges Geflecht aus dem Hybridgarn gebildet. Der Durchmesser des Rohrgeflechts richtet sich danach, wie dick der Rahmen an der jeweiligen Stelle sein soll; am Griff ist das Rohr im allgemeinen dicker als am ovalen Ring. Die Wanddicke des Geflechts liegt in der Größenordnung von 1 bis 2 mm. Man führt dann einen flexiblen, dünnwandigen (0,05 bis 2,0 mm) aufblasbaren Schlauch, vorzugsweise aus einem Kautschuk oder aus einer hochschmelzenden Kunststoffolie, in das rohrförmige Geflecht ein, anschließend wird das rohrförmige Geflecht in Form eines Tennisschlägerrahmens zusammengelegt.To manufacture the tennis racket frame according to the invention, a tubular braid is first formed from the hybrid yarn. The diameter of the cane depends on how thick the frame should be at each point; the tube is generally thicker on the handle than on the oval ring. The wall thickness of the braid is on the order of 1 to 2 mm. A flexible, thin-walled (0.05 to 2.0 mm) inflatable tube, preferably made of a rubber or a high-melting plastic film, is then inserted into the tubular braid, after which the tubular braid is folded together in the form of a tennis racket frame.

Nun wird die Brücke gebildet. Dazu formt man wieder ein rohrförmiges Hybridgarngeflecht, welches etwa die Länge der späteren Brücke hat und an beiden Enden jeweils zwei zungenförmige Segmente aufweist. In dieses Geflecht wird treibmittelhaltiges Thermoplast-Granulat bzw. Thermoplast-Strang eingegeben, zweckmäßigerweise in einem flachgelegten, flexiblen, dünnwandigen Schlauch, vorzugsweise aus dem gleichen thermoplastischen Kunststoff wie die Thermoplastfasern oder einem höherschmelzenden Kunststoff. Die Menge des eingefüllten Granulats sowie die Menge des darin enthaltenen Treibmittels bestimmen die Dichte des Schaums, der sich beim Erhitzen bildet, sowie den Innendruck, der dabei aufgebaut werden soll. Die Dichte soll zwischen 20 und 400 g/l, insbesondere zwischen 50 und 200 g/l liegen; der Innendruck in der Größenordnung von 5 bis 10 bar. Dieses Stück rohrförmigen Hybridgeflechts wird dann als Brücke so zwischen die Schenkel des Rahmens gelegt, daß die beiden Schenkel von den zungenförmigen Segmenten an den Endes des Geflechts umfaßt werden. Dieser Zustand ist in Abbildung 2 dargestellt.Now the bridge is built. To do this, a tubular hybrid yarn braid is again formed, which is approximately the length of the future bridge and has two tongue-shaped segments at each end. Thermoplastic granulate or thermoplastic strand containing blowing agent is introduced into this mesh, expediently in a flat, flexible, thin-walled hose, preferably made of the same thermoplastic material as the thermoplastic fibers or a higher melting plastic. The amount of granules filled in and the amount of blowing agent contained therein determine the density of the foam that forms when heated and the internal pressure that is to be built up in the process. The density should be between 20 and 400 g / l, in particular between 50 and 200 g / l; the internal pressure in the order of 5 to 10 bar. This piece of tubular hybrid braid is then placed as a bridge between the legs of the frame so that the two legs are encompassed by the tongue-shaped segments at the end of the braid. This state is shown in Figure 2.

Das Gebilde wird dann in eine mehrteilige, vorzugsweise zweiteilige Metallform gelegt, deren Innenflächen der gewünschten Form des fertigen Tennisschlägerrahmens entsprechen. Die Form wird geschlossen und der Schlauch wird zu einem Innendruck in der Größenordnung von 5 bis 10 bar aufgeblasen, wodurch das Hybridgarngeflecht gegen die Formwand gepreßt wird. Das Werkzeug wird dann auf eine Temperatur oberhalb des Schmelzpunktes der Thermoplastfasern erhitzt und etwa 3 bis 30 min bei dieser Temperatur gehalten. Das Aufblasen des Schlauchs kann auch gleichzeitig mit oder nach dem Erhitzen des Werkzeugs vorgenommen werden. Im Fall der Verwendung von Polyamidfasern liegt die Werkzeugtemperatur bei etwa 300°C. Dabei verschmelzen die Fasern zu einer konsolidierten Kunststoffmatrix, in der die Kohlenstoffasern orientiert eingelagert sind. Dabei verbinden sich auch die beiden Enden des Rohres und bilden den Griff des Schlägers, ferner verbinden sich die zungenförmigen Segmente der Brücke mit den Schenkeln, so daß die Brücke fest in den Rahmen eingebunden wird. Bei ausreichend hoher Werkzeugtemperatur schmilzt auch das Thermoplastgranulat in der Brücke auf, gasförmiges Treibmittel wird freigesetzt und preßt die Wände des die Brücke bildenden Geflechts fest an die Formwand, so daß auch dieses Hybridgarngeflecht konsolidiert. Das Werkzeug wird dann abgekühlt, der fertige Rahmen entformt und gegebenenfalls nachbearbeitet. Der flexible Schlauch kann herausgezogen oder im Rahmen belassen werden.The structure is then placed in a multi-part, preferably two-part metal mold, the inner surfaces of which correspond to the desired shape of the finished tennis racket frame. The mold is closed and the tube is inflated to an internal pressure of the order of 5 to 10 bar, whereby the hybrid yarn braid is pressed against the mold wall. The tool is then heated to a temperature above the melting point of the thermoplastic fibers and held at this temperature for about 3 to 30 minutes. The tube can also be inflated simultaneously with or after the tool has been heated. If polyamide fibers are used, the tool temperature is around 300 ° C. The fibers fuse to form a consolidated plastic matrix in which the carbon fibers are embedded. The two ends of the tube connect to form the handle of the racket, and the tongue-shaped segments of the bridge connect with the legs, so that the bridge is firmly integrated into the frame. If the mold temperature is sufficiently high, the thermoplastic granules also melt in the bridge, gaseous blowing agent is released and presses the walls of the braid forming the bridge firmly against the mold wall, so that this hybrid yarn braid is also consolidated. The tool is then cooled, the finished frame is demolded and, if necessary, reworked. The flexible hose can be pulled out or left in the frame.

Claims (10)

  1. A process for manufacturing a tennis racket frame comprising the steps of:
    a) forming a frame consisting of side pieces, said frame being formed of a tubular braid of thermoplastic fiber/carbon fiber hybrid yarn, into which a flexible, thin-walled, inflatable hose is inserted;
    b) inserting a bridge of tubular hybrid yarn braid between said side pieces;
    c) putting the frame and the bridge into a multipart metal mold which can be closed;
    d) inflating the hose; and
    e) heating the metal mold to an operating temperature,
    characterized in that
    f) prior to heating the metal mold, the bridge is partly filled with granules or a strand of a thermoplastic containing a propellant.
  2. The process according to claim 1, characterized in that the bridge has two tongue-shaped segments at the ends, respectively, said segments embracing said side pieces.
  3. The procees according to claim 1 or 2, characterized in that the hose is inflated simultaneously with or after the heating of the metal mold.
  4. The process according to one of claims 1 to 3, characterized in that the thermoplastic containing a propellant has a melting temperature which is lower than the operating temperature of the metal mold, thus expanding when the metal mold is heated.
  5. The process according to one of the preceding claims, characterized in that the hybrid yarn of the bridge is a thermoplastic fiber/carbon fiber hybrid yarn.
  6. The process according to one of the preceding claims, characterized in that the granules containing a propellant are contained in a flexible, thin-walled, inflatable hose, which has been inserted into the hybrid yarn braid of the bridge.
  7. The process according to one of the preceding claims, characterized in that the frame and the bridge consist of a hybrid yarn of consolidated thermoplastic fibers/carbon fibers.
  8. The process according to one of the preceding claims, characterized in that the foamed thermoplastic within the bridge shows a density between 20 g/l and 400 g/l.
  9. The process according to one of the preceding claims, characterized in that the thermoplastic fibers consist of a polyamide.
  10. The process according to one of the preceding claims, characterized in that the thermoplastic within the bridge consists of a polyamide, a polysulfone or a polyether sulfone.
EP93100859A 1992-01-29 1993-01-21 Method of manufacture of a tennis racket frame Expired - Lifetime EP0555666B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP96118475A EP0763372A3 (en) 1992-01-29 1993-01-21 Tennis racket frame

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4202335A DE4202335A1 (en) 1992-01-29 1992-01-29 TENNIS RACKET FRAME
DE4202335 1992-01-29

Related Child Applications (2)

Application Number Title Priority Date Filing Date
EP96118475A Division EP0763372A3 (en) 1992-01-29 1993-01-21 Tennis racket frame
EP96118475.1 Division-Into 1996-11-18

Publications (2)

Publication Number Publication Date
EP0555666A1 EP0555666A1 (en) 1993-08-18
EP0555666B1 true EP0555666B1 (en) 1997-05-21

Family

ID=6450432

Family Applications (2)

Application Number Title Priority Date Filing Date
EP93100859A Expired - Lifetime EP0555666B1 (en) 1992-01-29 1993-01-21 Method of manufacture of a tennis racket frame
EP96118475A Ceased EP0763372A3 (en) 1992-01-29 1993-01-21 Tennis racket frame

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP96118475A Ceased EP0763372A3 (en) 1992-01-29 1993-01-21 Tennis racket frame

Country Status (6)

Country Link
EP (2) EP0555666B1 (en)
JP (1) JPH05253322A (en)
CN (1) CN1079919A (en)
AT (1) ATE153247T1 (en)
DE (2) DE4202335A1 (en)
ES (1) ES2102535T3 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6953405B2 (en) 2002-02-19 2005-10-11 Stx, Llc Vibration damping field hockey stick
US7462118B2 (en) 2004-01-09 2008-12-09 Stx, Llc Back and edge weighted field hockey sticks

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102631768A (en) * 2012-03-19 2012-08-15 刘自平 Method for manufacturing solid racket
RU2762639C1 (en) * 2020-11-16 2021-12-21 Юрий Михайлович Тебенко Base of table tennis racket

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE795562A (en) * 1972-02-18 1973-06-18 Franz Volkl O H G TENNIS RACKET
DE3566128D1 (en) * 1984-03-15 1988-12-15 Basf Structural Materials Inc Composite carbon fibre and thermoplastic fiber blends
DE3925740A1 (en) 1989-08-03 1991-02-07 Basf Ag METHOD FOR PRODUCING EXPANDABLE GRANULES AND FOAMS THEREOF
GB2234909A (en) * 1989-08-05 1991-02-20 Heh Chien Hwa Racket frame
JPH0687903B2 (en) * 1989-12-05 1994-11-09 住友ゴム工業株式会社 Tennis racket frame

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6953405B2 (en) 2002-02-19 2005-10-11 Stx, Llc Vibration damping field hockey stick
US7462118B2 (en) 2004-01-09 2008-12-09 Stx, Llc Back and edge weighted field hockey sticks

Also Published As

Publication number Publication date
ES2102535T3 (en) 1997-08-01
ATE153247T1 (en) 1997-06-15
EP0763372A2 (en) 1997-03-19
CN1079919A (en) 1993-12-29
EP0763372A3 (en) 1997-03-26
DE59306477D1 (en) 1997-06-26
DE4202335A1 (en) 1993-08-05
EP0555666A1 (en) 1993-08-18
JPH05253322A (en) 1993-10-05

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