GB2240301A - Games racket frame - Google Patents
Games racket frame Download PDFInfo
- Publication number
- GB2240301A GB2240301A GB9001924A GB9001924A GB2240301A GB 2240301 A GB2240301 A GB 2240301A GB 9001924 A GB9001924 A GB 9001924A GB 9001924 A GB9001924 A GB 9001924A GB 2240301 A GB2240301 A GB 2240301A
- Authority
- GB
- United Kingdom
- Prior art keywords
- grommet
- racket
- grommet strip
- tubular members
- tubular
- 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.)
- Withdrawn
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/68—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts by incorporating or moulding on preformed parts, e.g. inserts or layers, e.g. foam blocks
- B29C70/86—Incorporated in coherent impregnated reinforcing layers, e.g. by winding
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
- B29C70/34—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
- B29C70/342—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation using isostatic pressure
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
- B29C43/10—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
- B29C43/12—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies using bags surrounding the moulding material or using membranes contacting the moulding material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/52—Sports equipment ; Games; Articles for amusement; Toys
- B29L2031/5245—Rackets
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Composite Materials (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Physical Education & Sports Medicine (AREA)
- Moulding By Coating Moulds (AREA)
Abstract
A games racket frame is made by assembling, in a compression mould, an integral grommet strip (10) together with two tubular members (30; 40), closing the mould and subjecting the contents to heat and pressure, whereby the tubular members (30; 40) become permanently bonded to the grommets and, between adjacent grommets, to each other. The grommet stop (10) is made of a material which is capable of bending, under the moulding conditions, with the material of the tubular members (30; 40). The grommet strip (10) may be made of an injection-mouldable thermoplastics material and the tubular members (30; 40) may be made of a fibre-reinforced thermosetting material. <IMAGE>
Description
GAMES RACKET FRAME
This invention relates to a games racket frame.
In particular, this invention relates to a method of making a moulded frame for a games racket and to a games racket frame made thereby.
Whilst the present invention will be described herein with particular reference to a frame for a tennis racket, it is not to be construed as being limited thereto. Other games rackets, for example squash rackets, rackets for "short-tennis", racketball and the like may also include frames made according to the method of the present invention.
Tennis racket frames are currently made by two basic methods (a) Compression moulding of fibre-reinforced
thermosetting materials; (b) Injection moulding of fibre-reinforced thermo
plastics materials.
In method a) the fibres are substantially continuous while in method b) they are discontinuous. Generally, compression moulding is a less convenient process than injection moulding, but articles of higher specific stiffness and strength can be produced.
One important advantage of injection moulding is that stringing holes can be moulded directly into the racket frame, whereas in compression moulding the holes must generally be provided by means of a separate operation (e.g. by drilling) after the moulding process is complete. This creates certain problems, in that the resulting holes tend to have sharp edges and in turn some form of grommet is required to protect the strings from damage.
Several methods for moulding stringing holes in a compression moulded racket frame have been proposed, but none has hitherto proved commercially satisfactory.
In particular, previously-proposed methods involving the use of retractable hole-forming pins have been found to result in mouldings containing areas of structural weakness.
We have now found that the above-mentioned problems may be minimised by means of the present invention.
The basic concept is first to mould a plurality of grommets, from a suitable material, to form an integral grommet strip. This grommet strip is then assembled, in a compression mould, together with two generally tubular members. In the resulting moulding, individual grommets of the grommet strip pass between the tubular members, which contact each other between the grommets and become bonded together at these positions.
Accordingly, the present invention provides a method of making a games racket frame, the frame comprising a head for stringing, a handle and a plurality of hollow string-protecting grommets constituting an integral grommet strip and extending through the head in the plane of the stringing, in which a first tubular member is placed in a compression mould, the grommet strip is superposed on the first tubular member, a second tubular member is superposed on the grommet strip, the mould is closed and the mould contents are subjected to heat and pressure, whereby the first and second tubular members become permanently bonded to each other and to the grommet strip.
The grommet strip is preferably made of a material capable of bonding, under the moulding conditions, with the material of the tubular members.
Suitably, the grommet strip is made of an injectionmouldable thermoplastics material. For example, the grommet strip may be made of a material comprising a poly(phenylene)ether. A particularly preferred material for making the grommet strip is
poly (2, 6-dimethyl-l, 4-phenylene) oxide, available from Huls AG under the Registered Trade Mark
VESTORAN.
The two tubular members may suitably comprise a fibre-reinforced thermosetting material.
Preferably, the fibres are continuous and may be in the form of one or more layers of a fabric wrap or one or more layers of a braided tube.
The tubular members may be formed by first impregnating the fibres with a thermosetting resin then laying the fibres around a mandrel and placing the assembly in the mould.
It is particularly convenient for the mandrel to be an inflatable mandrel, whereby during the moulding process the tubular assemblies are urged into bonding contact with each other and with the grommet strip.
The fibres may comprise fibres of carbon, glass, polyamide, or aramid or a combination thereof.
Suitable thermosetting materials include epoxy polyester and methacrylate resins.
In a preferred embodiment of the present invention, the grommet strip comprises a plurality of hollow tubular grommets joined together at one end by means of a joining member.
In a second preferred embodiment, the grommet strip comprises a plurality of hollow tubular grommets joined at each end to one of a pair of joining members to form a generally ladder-like structure.
In a further preferred embodiment, each joining member is so shaped that on completion of the moulding it partially or substantially encloses one or both of the tubular members.
In a still further embodiment, each grommet may be provided with a removable plug at one or both open ends to prevent ingress of moulding material during the moulding process.
Each grommet may be of substantially circular cross-section.
Alternatively, each grommet may be of a noncircular (for example, oval) cross-section to facilitate bonding of the tubular members to the grommets and, between the grommets, to each other
It will be appreciated that the temperature of the moulding process must be chosen so that the grommet strip is not softened and distorted by the pressure of the inflatable mandrels which provide the overall moulding pressure. This can be achieved by the choice of suitable thermosetting resins for use with the tubular assemblies.
Preferred embodiments of the present in#vention will be illustrated, merely by way of example, in the following description and with reference to the accompanying drawings.
In the drawings (wherein like numerals denote like parts):
Figure 1 is a perspective view of an integral
grommet strip for use in accordance
with the present invention;
Figure 2 is a section on line II-II of Figure
1;
Figure 3 is a section through a mould prior
to making a racket frame according
to one embodiment of the present invention
Figure 4 is a view from below of a portion
of a racket frame made in the mould
of Figure 3;
Figures 5 and 6 are respectively sections through å racket frame according to second
and third embodiments of the present
invention;
Figure 7 is a view from below of a portion
of a racket frame according to a further
embodiment of the present invention;
and
Figure 8 is a section on line VIII-VIII of
Figure 7.
Referring to Figures 1 and 2, a grommet strip 10 comprises a plurality of hollow grommets 11. Each grommet 11 is provided with an opening 12 at one end and an opening 13 at the opposite end, to allow passage of the stringing of the completed racket. The grommets 11 are integrally formed with a joining member 14 so that each grommet has its opening 12 in the plane of the joining member 14 and all grommets extend from the joining member 14 in the same direction and at substantially 900 to member 14.
In Figure 3, a pair of complementary mould parts 21 and 22 define between them a moulding cavity 23, about a mould parting-line 24.
A first tubular assemb y 30, comprising a resinimpregnated fibrous wrap 31 on an inflatable mandrel 32, is placed in one half of the cavity 23. A grommet strip 10 is laid above the assembly 30 and a second tubular assembly 40 (comprising a resin-impregnated fibrous wrap 41 on an inflatable mandrel 42) is laid above the grommet strip 10.
The mould is then closed and the mandrels 32 and 42 are inflated to urge assemblies 30 and 40, during moulding, into bonding contact with each other and with the grommet strip 10.
Figure 4 shows a portion of a racket frame, made in the mould of Figure 3 and comprising tubular members 30 and 40 moulded integrally with grommet strip 10. The tubular members 30 and 40 are bonded to the grommets 11 and, between the grommets, to each other.
Referring to Figure 5, the grommet strip 50 has a joining member 51 which is shaped so as to partially enclose tubular members 30 and 40 when moulding is complete.
In Figure 6, the grommet strip 60 has a joining member 61 which is shaped so as to substantially enclose tubular members 30 and 40 when moulding is complete.
Referring now to Figures 7 and 8, the grommet strip 70 is provided with grommets 71 which are of generally oval cross-section. This facilitates bonding of the tubular member530 and 40 to the grommets 71 and, between the grommets, to each other.
Claims (27)
1. A method of making a games racket frame, the frame comprising a head for stringing, a handle and a plurality of hollow string-protecting grommets constituting an integral grommet strip and extending through the head in the plane of the stringing, in which a first tubular member is placed in a compression mould, the grommet strip is superposed on the first tubular member, a second tubular member is superposed on the grommet strip, the mould is closed and the mould contents are subjected to heat and pressure, whereby the first and second tubular members become permanently bonded to each other and to the grommet strip.
2. A method according to Claim 1, in which the grommet strip is made of a material capable of bonding, under the moulding conditions, with the material of the tubular members.
3. A method according to Claim 2, in which the grommet strip is made of an injection-mouldable thermoplastics material.
4. A method according to Claim 2 or 3, in which the grommet strip is made of a material comprising a poly(phenylene)ether.
5. A method according to Claim 4, in which the grommet strip is made of
poly (2,6-dimethyl-1, 4-phenylene) oxide.
6. A method according to any one of Claims 1 to 5, in which the tubular members comprise a fibrereinforced thermosetting material.
7. A method according to Claim 6, in which the fibres are continuous.
8. A method according to Claim 6 or 7, in which the fibres comprise one or more layers of a fabric wrap.
9. A method according to Claim 6 or 7, in which the fibres comprise one or more layers of a braided tube.
10. A method according to any one of Claims 6 to 9, in which the fibres are laid around a mandrel to form the tubular members.
11. A method according to Claim 10, in which the mandrel is an inflatable mandrel.
12. A method according to Claim 11, in which inflation of the inflatable mandrel during the moulding process urges the tubular members into contact with each other and with the grommet strip.
13. A method according to any one of Claims 6 to Claim 12, in which the fibres are of carbon, glass, poylamide, aramid or a combination thereof.
14. A method according to any one of Claims 6 to 13, in which the thermosetting material is an epoxy, a polyester or a methacrylate resin.
15. A method according to any one of Claims 1 to 14, in which the grommet strip comprises a plurality of hollow tubular grommets joined together at one end by means of a joining member.
16. A method according to any one of Claims 1 to 14, in which the grommet strip comprises a plurality of hollow tubular grommets joined at each end to one of a pair of joining members to form a generally iadderlike structure.
17. A method according to any one of Claims 1 to 16, in which each joining member is so shaped that on completion of the moulding it partially or substantially encloses one or both of the tubular members.
18. A method according to any one of Claims 1 to 17, in which each grommet is provided with a removable plug at one or both open ends to prevent ingress of moulding material during the moulding process.
19. A method according to any one of Claims 15 to 18, in which each grommet is of substantially circular cross-section.
20. A method according to any one of Claims 15 to 18, in which each grommet is of non-circular crosssection.
21. A method according to Claim 20, in which each grommet is of generally oval cross-section.
22. A method of making a games racket frame, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
23. A games racket frame made by the method of any one of Claims 1 to 22.
24. A games racket having a frame according to
Claim 23.
25. A racket according to Claim 24, which is a tennis racket.
26. A racket according to Claim 24, which is a squash racket.
27. A racket according to Claim 24, which is a "short-tennis racket or a racketball racket.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9001924A GB2240301A (en) | 1990-01-27 | 1990-01-27 | Games racket frame |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9001924A GB2240301A (en) | 1990-01-27 | 1990-01-27 | Games racket frame |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9001924D0 GB9001924D0 (en) | 1990-03-28 |
| GB2240301A true GB2240301A (en) | 1991-07-31 |
Family
ID=10670035
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9001924A Withdrawn GB2240301A (en) | 1990-01-27 | 1990-01-27 | Games racket frame |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2240301A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998028049A1 (en) * | 1996-12-23 | 1998-07-02 | Prince Sports Group, Inc. | Notched, slotted grommet for sports racquet |
| US5833560A (en) * | 1997-03-19 | 1998-11-10 | Prince Sports Group, Inc. | Racquetball racquet |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1312543A (en) * | 1970-07-29 | 1973-04-04 | Robin J | Method of making a frame for a tennis racket |
| GB1366773A (en) * | 1972-06-20 | 1974-09-11 | Kicherer K H | Method of producing a racket frame |
| US4031181A (en) * | 1972-04-05 | 1977-06-21 | General Dynamics Corporation | Method for molding high strength facing |
| GB1554353A (en) * | 1976-07-13 | 1979-10-17 | Bosch Gmbh Robert | Tennis rackets |
-
1990
- 1990-01-27 GB GB9001924A patent/GB2240301A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1312543A (en) * | 1970-07-29 | 1973-04-04 | Robin J | Method of making a frame for a tennis racket |
| US4031181A (en) * | 1972-04-05 | 1977-06-21 | General Dynamics Corporation | Method for molding high strength facing |
| GB1366773A (en) * | 1972-06-20 | 1974-09-11 | Kicherer K H | Method of producing a racket frame |
| GB1554353A (en) * | 1976-07-13 | 1979-10-17 | Bosch Gmbh Robert | Tennis rackets |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998028049A1 (en) * | 1996-12-23 | 1998-07-02 | Prince Sports Group, Inc. | Notched, slotted grommet for sports racquet |
| US5833560A (en) * | 1997-03-19 | 1998-11-10 | Prince Sports Group, Inc. | Racquetball racquet |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9001924D0 (en) | 1990-03-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |