GB2440509A

GB2440509A - Method of forming a badminton racquet having a T shaped joint

Info

Publication number: GB2440509A
Application number: GB0615263A
Authority: GB
Inventors: Tseng Yi Sheng
Original assignee: Dunlop Slazenger Group Ltd
Current assignee: Dunlop International Group Ltd
Priority date: 2006-08-01
Filing date: 2006-08-01
Publication date: 2008-02-06
Anticipated expiration: 2026-08-01
Also published as: GB0615263D0; GB2440509B

Abstract

A method of forming a badminton racquet having a head portion 22 and handle portion 24 formed of fibre reinforced plastics tubes, connected by a hollow, tubular 'T' shaped joint member 30, includes the steps of (a) forming prepreg head and handle tubes 22, 24, (b) bending head tube 22 into a loop, (c) connecting the ends of head tube 22 to the transverse ends 321 of joint 30, (c) connecting the end 241 of handle tube 24 to the free longitudinal end 341 of joint 30, such that head 22 and handle tube 24 are in communication via joint 30, (d) placing the tubes 22, 24 and joint 30 into a die 42, (e) inflating head tube 22 through handle tube 24 to force head tube 22 against an inner wall of die 42, and (f) curing head tube 22 so that head tube 22 and joint 30 are joined together. Three prepregs 40 may be wound around the connections of head tube 22, joint 30 and handle tube 24 before step (d). Handle tube 24 may also be inflated to press against the die and cured in steps (e) and (f), or may be cured prior to step (c).

Description

-1 2440509

BADMINTON RACQUET AND METHOD OF MANUFACTURING IT

The present invention relates to a badminton racquet and method of making it.

A conventional method of manufacturing badminton racquet is shown in Figure I In this, a prepreg is wound into a tube. The tube is bent into a frame 1. The frame I comprises an elliptical head 2 and a straight rod 3. An inlet 4 into the frame I is disposed at one end of the straight rod 3. The frame 1 is placed into a die (not shown). Then the frame I is inflated through the inlet 4 to force the frame I against an inner walls of the die. The frame 1 is then cured to form the badminton racquet.

Because the badminton racquet is integrally formed from a single material, the vibration energy generated by hitting the shuttle is transmitted directly to the user. and can cause injury to the user after a long time of use. Besides this, the prepreg is bent nearly 90 degrees at the connection 5 of the head 2 and the rod 3 so that the fibres of the prepreg are seriously twisted. The connection 5 becomes susceptible to structural defects and the racquet can break easily.

This problem can be serious since the connection 5 is the position at which the stress converges when the racquet hits the shuttle. . . * I * S.

The present invention seeks to provide a badminton racquet and method of manufacturing a badminton racquet which has improved vibration absorption properties.

The present invention also seeks to provide a badminton racquet and a method of manufacturing badminton racquet with improved structural strength.

According to a first aspect of the invention, a badminton racquet comprises a head portion formed of a fibre containing plastics material tube bent into a loop shape with the ends of the tube facing generally towards each other with a gap in between, a handle portion formed of a straight fibre containing plastics material tube and a joint member of a different material from that of the head portion and the handle portion connecting the head portion and the handle portion, the joint member being of generally MT" shaped form with the transverse or head portion of the MT being curved to correspond to the shape of the head and connected by its two ends to the two ends of the tube and the free end of the longitudinal or stem portion of the "T" being connected to the handle portion, the ends of the tubes and the ends of the joint member (30) being positioned within one another. *S

S

5.' The ends of the tubes may be located within the ends of the joint member or the ends of the joint member may be located within the ends of the tubes.

S

** The tubes and the joint member may secured together by strips of prepreg p. S material wound around the joints and thereafter cured or by glue.

According to a second aspect of the invention, a method of manufacturing a badminton racquet comprises (a) winding two prepregs into a first tube and a second tube respectively, wherein the second tube has a connecting end and an inlet end: (b) bending the first tube so that its ends face generally towards each other and connecting the first tube and the second tube together by a joint member of a different material to the tubes, wherein the joint member is of generally "T" shape with a transverse or head portion, a longitudinal or stem portion extending from a middle of the transverse or head portion, a chamber inside the joint member and three openings disposed at the two ends of the transverse or head portion and the connecting end of the longitudinal or stem portion respectively so that the chamber is open to the exterior; wherein the two ends of the first tube are connected to the two ends of the transverse or head portion of the joint member and the connecting end of the second tube is connected to the end of the longitudinal or stem portion of the joint member with the ends of the tubes and the ends of the joint member positioned one within the other and so that an inside of the second tube is in communication with an inside of the first tube through the openings and chamber of the joint member; and S.. (C) placing the first tube, the second tube and the joint member assembled together into a die, then inflating at least the first tube through the inlet of the second tube to force at least the first tube against an inner wall of ** the die, and then curing at least the first tube so that at least the first tube and :**. the joint member are joined together.

The two ends of the first tube may be inserted into the openings of the transverse or head portion of the joint member or the two ends of the first tube may be sleeved onto the two ends of the transverse or head portion of the joint member in step (b).

The first tube, the second tube and the joint member may be connected with each other by winding a prepreg respectively around the connections of the first tube, the joint member and the second tube or by gluing them in step (b).

The joint member may be made of a thermoplastic plastics material containing short fibresof nylon containing short fibres. The short fibres may be carbon fibres or glass fibres.

Alternatively, the joint member may be made of a metal or a metal alloy.

The two ends of the transverse or head portion of the joint member and the end of the longitudinal or stem portion of the joint member remote from the transverse or head portion may be provided with a plurality of longitudinal notches extending inwardly from the end.

In step C) the second tube may be also inflated in the die to force the second tube against the inner wall of the die and the second tube is also cured with the *. first tube in the die * . Alternatively, the second tube may be manufactured by winding a prepreg onto a mandrel and then curing the prepreg prior to assembling it to the joint member.

The invention will now be describes in greater detail, by way of example, with reference to the drawings, in which:-FIG. 1 is a perspective view of a frame made according to a conventional method.

FIG. 2 is a perspective view of a badminton racquet in accordance with a preferred embodiment of the present invention.

FIG. 3 is a schematic view of a first step in the manufacture of a badminton racquet as shown in FIG. 1; FIG. 4 is a schematic view of a second step in the manufacture of a badminton racquet as shown in FIG. 1; FIG. 5 is a sectional view taken along the 5-5 line in FIG. 4.

FIG. 6 is a schematic view of a third step in the manufacture of a badminton racquet as shown in FIG. 1;

I I

I

FIG. 7 is a partial perspective view of a badminton racquet according to a second embodiment of the present invention.

FIG. 8 is a schematic view of step of preparing a hollow rod according to a third embodiment of the present invention, and FIG. 9 is a schematic view of the connection of a hollow rod, a first tube and a joint member according to the third embodiment of the present invention.

Referring to FIG. 2, there is shown a badminton racquet 10 according to the first preferred embodiment of the present invention. This comprises a head frame 12, a shaft 14 and a handle 16.

A method, in accordance with the invention, of manufacturing the badminton racquet 10 will now be described:-First, a first tube 22 and a second tube 24 respectively, are wound from prepregs. one tube 24 is maintained straight 2 while The first tube 22 is formed into a generally half hoop shape while the second tube 24 is maintained straight as shown in FIG. 3. The second tube 24 has a connecting part 241 at one end and an inlet 243 to the tube 24 at its other end. Examples of the fibre which can be used in the prepregs includes carbon fibre, glass fibre, boron fibre or Kevlar fibre although any other suitable fibre can be used.

Then, one end of the first tube 22 is connected to the second end of first tube 22 and to the second tube 24 by means of a joint member 30, as shown in FIG. 4. The joint member 30 is suitably made of nylon 304 containing short fibres 302 (see FIG. 5). The short fibres 302 may be carbon fibres. In fact, the nylon 304 can be replaced by a thermoplastic plastics material and the short fibres 302 can be replaced by glass other suitable fibres. Even the joint member 30 can be made of metal or an alloy to achieve the results of the present invention.

The joint member 30 is generally of "T" shape and has a transverse or head portion 32, a longitudinal or stem portion 34 extending substantially at right angles from a middle of the transverse portion 32. A chamber 36 is provided inside the joint member 30 and there are three openings 321, 341 disposed at two ends of the transverse or head portion 32 and one end of the longitudinal or stem portion 34 respectively and communicating the chamber 36. The two ends of the first tube 22 are inserted into the two openings 321 of the transverse or head portion 32 of the joint member 30 and the connecting end 241 of the second tube 24 is inserted into the opening 341 of the longitudinal or stem portion 34 of the joint member 30 so that an inside of the second tube 24 is in communication with the inside of the first tube 22 through the chamber 36 of the joint member 30. The transverse or head portion 32 of the joint member 30 is curved to match that of the first tube 22. Besides, the two ends of the transverse or head portion 32 of the joint member 30 and the end of the longitudinal or stem portion 34 of the joint member 30 remote from the ::* transverse or head portion 32 are provided with a plurality of notches 38 to facilitate insertion of the first tube 22 and the second tube 24 into the joint V member 30. * S

I

Then, three prepregs 40 are wound respectively around the connections of the first tube 22, the joint member 30 and the second tube 24 so as to connect them firmly together. The two ends of the transverse or head portion 32 of the joint member 30 and the end of the longitudinal or stem portion 34 of the joint member 30 remote from the transverse or head portion 32 are provided with ripples 39 to increase the friction between the joint member 30 and the prepregs 40 so that the prepregs 40 are firmly wound around the joint member 30.

Finally, the first tube 22, the second tube 24 and the joint member 30 are placed together into a die 42 (FIG 6). The die is heated and inflate the first tube 22 and the second tube 24 are inflated through the inlet 243 to force the two tubes 22, 24 against an inner wall 44 of the die 42, The heat from the die will cure the two tubes 22, 24 so that the first tube 22, the second tube 24 and the joint member 30 are joined together. The first tube 22 and the transverse or head portion 32 of the joint member 30 jointly become the head frame 12 of the badminton racquet 10. The second tube 24 and the longitudinal or stem portion 34 of the joint member 30 jointly become the shaft 14 of the badminton racquet 10. The badminton racquet 10 is finished after the handle 16 is mounted at the end of the shaft 14.

Because the material of the joint member 30 is different from that of the first tube 22 and the second tube 24, vibration energy generated by hitting a shuttle can be reduced when the vibration waves transmitted from the first tube 22, the joint member 30 to the second tube 24. Thus the badminton racquet 10 manufactured according to the method of the present invention has improved vibration absorption ability. Furthermore, the joint member 30 is made of nylon 304 containing short fibres 302. The joint member 30 has great structural strength so that it can avoid structural defects around the connection of the head 2 and the rod 3 in conventional badminton racquet and lengthen the life of the racquet.

The way in which the joint member 30 is connected with the first tube 22 can be changed. As shown in FIG. 7, a badminton racquet manufactured in accordance with a second embodiment of the present invention comprises a first tube 52, a second tube 54 and a generally "1" shaped joint member 60 which are the same as in the badminton racquet 10 of the first embodiment of the present invention. The differences between them are that the two ends of the first tube 52 are sleeved onto the two ends of the transverse or head portion 62 of the joint member 60, and the first tube 52, the second tube 54 and the joint member 60 are connected to each other by glue, and the joint member 60 has no notches and ripples. The second tube 54 may also be sleeved onto the joint member 60 or may be inserted into the joint member 60 as in the first embodiment.

The shaft of the badminton racquet can also be manufactured by different processes. As shown in FIGS. 8-9, the method of manufacturing badminton racquet according to a third embodiment of the present invention comprises the following steps. * S

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First, a prepreg 70 is wound onto a mandrel 72 and then the prepreg 70 is cured to form a hollow rod 74. The hollow rod 74 has a connecting end and an inlet 742. Another prepreg is wound into a first tube 76 at the same stage.

Then, the hollow rod 74 and the first tube 76 are connected with a joint -10 -member 80. The inside of the hollow rod 74 is in communication with the inside of the first tube 76 through the joint member 80. At this time, the hollow rod 74 is already cured and hardened but the first tube 76 is not yet cured and hardened. The first tube 76, the hollow rod 74 and the joint member 80 are connected with each other by winding three prepregs 78 respectively around connections of the first tube 76, the joint member 80 and the hollow rod 74.

Finally, the first tube 76, the hollow rod 74 and the joint member 80 are placed together into a die (not shown). The first tube 76 is inflated through the inlet 742 of the hollow rod 74 to force the first tube 76 against the inner wall (not shown) of the die. Then the first tube 76 is cured so that the first tube 76, the joint member 80 and the hollow rod 74 are joined together. I.

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S S. S.

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S * S * S S.

Claims

-11 -CLAIMS: 1. A badminton racquet comprising a head portion formed of

a fibre containing plastics material tube bent into a loop shape with the ends of the tube facing generally towards each other with a gap in between, a handle portion formed of a straight fibre containing plastics material tube and a joint member of a different material from that of the head portion and the handle portion connecting the head portion and the handle portion, the joint member being of generally "T" shaped form with the transverse or head portion of the "T" being curved to correspond to the shape of the head and connected by its two ends to the two ends of the tube and the free end of the longitudinal or stem portion of the "T" being connected to the handle portion, the ends of the tubes and the ends of the joint member (30) being positioned within one another.

:
2. A badminton racquet as claimed in claim 1, wherein the ends of the tubes are located within the ends of the joint member.

3. A badminton racquet as claimed in claim 1, wherein the ends of the joint member are located within the ends of the tubes.

S * . S.

4. A badminton racquet as claimed in claim 1, 2 or 3, wherein the tubes and the joint member are secured together by strips of prepreg material wound around the joints and thereafter cured.

-12 - 5. A badminton racquet as claimed in claim 1, 2 or 3, wherein the tubes and the joint member are secured together by glue.

6. A method of manufacturing a badminton racquet comprising (a) winding two prepregs into a first tube and a second tube respectively, wherein the second tube has a connecting end and an inlet end; (b) bending the first tube so that its ends face generally towards each other and connecting the first tube and the second tube together by a joint member of a different material to the tubes, wherein the joint member is of generally "T" shape with a transverse or head portion, a longitudinal or stem portion extending from a middle of the transverse or head portion, a chamber inside the joint member and three openings disposed at the two ends of the transverse or head portion and the connecting end of the longitudinal or stem portion respectively so that the chamber is open to the exterior; wherein the two ends of the first tube are connected to the two ends of the transverse or head portion of the joint member and the connecting end of the second tube is connected to the end of the longitudinal or stem portion of the joint member with the ends of the tubes and the ends of the joint member positioned one within the other and so that an inside of the second tube is in communication with an inside of the first tube through the openings and chamber of the joint member; and (C) placing the first tube, the second tube and the joint member assembled together into a die, then inflating at least the first tube through the inlet of the second tube to force at least the first tube against an inner wall of the die, and then curing at least the first tube so that at least the first tube and -13 -the joint member are joined together.

7. The method of claim 6, wherein the two ends of the first tube are inserted into the openings of the transverse or head portion of the joint member in step (b).

8. The method of claim 6, wherein the two ends of the first tube are sleeved onto the two ends of the transverse or head portion of the joint member in step (b).

9 The method of claim 6, 7 or 8, wherein the first tube, the second tube and the joint member are connected with each other by winding a prepreg respectively around the connections of the first tube, the joint member and the second tube in step (b).

S I.

The method claim 6, 7, or 8, wherein the first tube, the second tube and the joint member are connected with each other by gluing connections of the first tube, the joint member and the second tube in step (b). S*

S S

S

: * 11. The method of any one of claims 6 to 10, wherein the joint member is made of a thermoplastic plastics material containing short fibres 12. The method of any one of claims 6 to 10, wherein the joint member is made of nylon containing short fibres.

-14 - 13. The method of claim 11 or 12, wherein the short fibres are carbon fibres or glass fibres.

14. The method of any one of claims 6 to 10, wherein the joint member is made of a metal or a metal alloy.

15. The method of any one of claims 6 to 14, wherein the two ends of the transverse or head portion of the joint member and the end of the longitudinal or stem portion of the joint member remote from the transverse or head portion are provided with a plurality of longitudinal notches extending inwardly from the end.

16. The method of any one of claims 6 to 15, wherein, in step C) the second tube is also inflated in the die to force the second tube against the inner wall of the die and the second tube is also cured with the first tube in the die "S p..

S

17. The method of any one of claims 6 to 15, wherein the second tube is 4' manufactured by winding a prepreg onto a mandrel and then curing the prepreg prior to assembling it to the joint member. S. -* S.

18. A badminton racquet substantially as described herein with reference to the drawings.

19. A method of manufacturing badminton racquet substantially as described

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herein with reference to the drawings. I. * . Is.*

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Amendments to the cLaims have been fiLed as foLLows CLAIMS: 1. A badminton racquet comprising a head portion formed of a single fibre containing plastics material tube bent into a loop shape with the ends of the tube facing generally towards each other with a gap in between, a handle portion formed of a straight fibre containing plastics material tube and a hollow joint member of a different material from that of the head portion and the handle portion connecting the head portion and the handle portion, the joint member being of generally "1" shaped form with the transverse or head portion of the 1T' being curved to correspond to the shape of the head and connected by its two ends to the two ends of the tube and the free end of the longitudinal or stem portion of the "T" being connected to the handle portion, the ends of the tubes with the ends of the joint member being positioned within one another and each of the three connections being individually wrapped in cured prepreg material so that outer surface of the joint member forms a part of the exterior surface of the racquet 2. A badminton racquet as claimed in claim 1, wherein the ends of the tubes are located within the ends of the joint member.

3. A badminton racquet as claimed in claim 1, wherein the ends of the joint member are located within the ends of the tubes.

4. A badminton racquet as claimed in claim 1, 2 or 3, wherein the tubes and the joint member are secured together by strips of prepreg material wound around the joints and thereafter cured.

5. A method of manufacturing a badminton racquet comprising (a) winding two prepregs into a first tube and a second tube respectively, wherein the second tube has a connecting end and an inlet end; (b) bending the first tube so that its ends face generally towards each other and connecting the first tube and the second tube together by a joint member of a different material to the tubes, wherein the joint member is of generally "T" shape with a transverse or head portion, a longitudinal or stem portion extending from a middle of the transverse or head portion, a chamber inside the joint member and three openings disposed at the two ends of the transverse or head portion and the connecting end of the longitudinal or stem portion respectively so that the chamber is open to the exterior; wherein the two ends of the first tube are connected to the two ends of the transverse or head portion of the joint member and the connecting end of the second tube is connected to the end of the longitudinal or stem portion of the joint member with the ends of the tubes and the ends of the joint member positioned one within the other and so that an inside of the second tube is in communication with an inside of the first tube through the openings and chamber of the joint member; (c) wrapping prepreg around the ends of the joint member and the ends of the tubes located therein leaving the rest of the joint member free and (d) placing the first tube, the second tube and the joint member assembled together into a die, then inflating at least the first tube through the inlet of the second tube to force at least the first tube against an inner wall of the die, and then curing the tubes and prepreg wrapping so that at least the first tube and the joint member are joined together.

6. The method of claim 5, wherein the two ends of the first tube are inserted into the openings of the transverse or head portion of the joint member in step (b).

7. The method of claim 5, wherein the two ends of the first tube are sleeved onto the two ends of the transverse or head portion of the joint member in step (b).

8 The method of claim 5, 6 or 7, wherein the first tube, the second tube and the joint member are connected with each other by winding a prepreg respectively around the connections of the first tube, the joint member and the second tube in step (b).

9. The method of any one of claims 5 to 8, wherein the joint member is made of a thermoplastic plastics material containing short fibres 10. The method of any one of claims 5 to 9, wherein the joint member is made of nylon containing short fibres.

11. The method of claim 9 or 10, wherein the short fibres are carbon fibres or glass fibres.

12. The method of any one of claims 5 to 8, wherein the joint member is made of a metal or a metal alloy.

13. The method of any one of claims 5 to 12, wherein the two ends of the transverse or head portion of the joint member and the end of the longitudinal or stem portion of the joint member remote from the transverse or head portion are provided with a plurality of longitudinal notches extending inwardly from the end.

14. The method of any one of claims 5 to 13, wherein, in step c) the second tube is also inflated in the die to force the second tube against the inner wall of the die and the second tube is also cured with the first tube in the die 15. The method of any one of claims 5 to 13, wherein the second tube is manufactured by winding a prepreg onto a mandrel and then curing the prepreg prior to assembling it to the joint member. tcl

16. A badminton racquet substantially as described herein with reference to the drawings.

17. A method of manufacturing badminton racquet substantially as described herein with reference to the drawings.