GB2333970A

GB2333970A - Shuttlecock

Info

Publication number: GB2333970A
Application number: GB9802818A
Authority: GB
Inventors: Richard Peter Harding
Original assignee: Dunlop Slazenger Group Ltd
Current assignee: Dunlop International Group Ltd
Priority date: 1998-02-10
Filing date: 1998-02-10
Publication date: 1999-08-11
Also published as: TW358749B; CN1227130A; GB9802818D0; JPH11267259A

Abstract

A hybrid plastic shuttlecock made of two different types of plastic for improved physical properties. A first type of plastic is used to form a stem assembly (1) having a base (2) to which a cork (12) is attached and from which a plurality of stems (5) extend. The "feathers" of the shuttlecock are provided by vanes (10) attached to each of the stems, the vanes being formed of a second type of plastic. The stem assembly may be produced by injection moulding, and the vanes by stamping from film material. The same basic material may be used for both the stem assembly and the vanes, different properties being achieved by different processing and/or by reinforcing the stems with fibre.

Description

Shuttlecock Shuttlecocks for the game of Badminton consist essentially of a striking member or 'cork' to which are attached 'flights' which provide direction and stability to the trajectory of the shuttlecock after it has been struck. The flights need to be light (so that the resulting shuttlecock is nose-heavy), be capable of rapid recovery from deformation and tough so that they can resist multiple deformations when repeatedly struck by a racket. Traditionally, these qualities have been met by the use of trimmed goose feathers assembled on the notional surface of the frustum of a cone with the smaller diameter of the frustum coinciding with the cork.

So called synthetic shuttlecocks are known in which the assembly of feathers are replaced by a plastic moulding consisting of a series of stems (representing the stems of the feathers) and a 'skirt' which is a lace-like structure attached to and joining all the stems so imitating the assembled vanes of the feather shuttlecock. The stems and vanes form an integral structure made by a process of injection moulding using suitable plastic material which can easily flow in a mould to form the intricate combined stem and lace structure, while providing suitable qualities of stiffness, toughness and recovery from deformation.

Because the integrated assembly is injection moulded both stems and vanes are of necessity made from the same plastic material and so a compromise is necessary in the properties afforded to them. Ideally, it is desirable that the stems should be stiffer than the compromise material allows and the necessary flow properties of the material suitable for producing the lace-like structure of the vanes prohibits the use of material most suitable for the stems.

The present invention addresses the above problem and enables a shuttlecock to be made wherein different materials can be used for the stems and vanes.

Preferably, the stems and vanes are separately manufactured and subsequently assembled to form a 'hybrid' shuttlecock with improved physical properties and playing characteristics.

According to a first aspect of the present invention there is provided a shuttlecock comprising: a striking member; a stem assembly having a base to which the striking member is attached and a plurality of stems extending from the base; and a plurality of vanes, each of which is attached to a respective one of the stems; wherein the stem assembly and the vanes are made of plastics material and the stem assembly is formed as a one-piece moulding, the plastics material used for the stem assembly having different properties from that used for the vanes. In one embodiment, the plastics material used for the stem assembly is a different basic material from that of the vanes. In an alternative embodiment, the same basic material is used for the stem assembly and the vanes, but processed in different ways so as to give different physical properties to the stem assembly and the vanes.

The one-piece moulding of the stem assembly is preferably achieved by injection moulding, and the vanes can conveniently be made by stamping from a film of plastics material.

There are various ways of attaching the vanes to the stems: by adhesive, by welding, or by mechanical means (e.g. stitching or stapling). These ways can be combined if desired.

In a preferred embodiment of the invention, the base comprises an attachment member to which the striking member is attached, and a disc-shaped portion from which the stems extend in a frusto-conical shape, the stems being linked part way along their lengths by at least one binding ring. Preferably also, each of the stems has a spade portion formed part way along its length, for facilitating attachment of its respective vane.

In a further preferred embodiment, each of the stems has a channel-shaped section.

The vanes may overlap one with another when assembled on the stems, and optionally the vanes are attached together where they overlap.

The stems can incorporate reinforcing fibre as a minor component.

According to a second aspect of the invention, there is provided a method of manufacturing a shuttlecock comprising the steps of: forming a stem assembly comprising a base and a plurality of stems extending from the base, by injection moulding of plastics material; forming a plurality of vanes by stamping from a film of plastics material; attaching one of the vanes to each of the stems, respectively; and attaching a striking member to the base.

Thus, the present invention enables the stems and vanes to be provided separately, made from materials having different properties as a result of being of different basic materials or of the same basic material subjected to different manufacturing processes, so that the desirable characteristics of each are optimised.

Moreover, all but the cork and vanes is formed as one integral piece for ease of assembly.

Reference will now be made, by way of example only, to the accompanying drawings in which: Figure 1 shows a stem assembly and a striking member for attachment thereto; Figure 2 shows a plurality of vanes in overlapping arrangement; Figure 3(a) shows a 'short' stem having a short spade, to which a vane is attached; Figure 3(b) shows a 'long' stem having a long spade, to which a vane is attached; and Figure 3 (c) shows a cross-section AA' of the stems and vane in Figures 3 (a) and (b).

Referring first to Figure 1, a stem assembly 1 is illustrated which provides a shell for the shuttlecock.

This stem assembly comprises a base 2 having an attachment member 3, to which a striking member 12 such as a cork can be attached as indicated, and a generally disc-shaped portion 4. Here, the term "cork" covers both natural cork and synthetic cork, the latter typically being an expanded thermoplastic material such as suitable compounds of ethylene-vinyl-acetate.

From the disc-shaped portion 4 a plurality of stems 5 extend, each inclined outwards at an obtuse angle to the base so as to lie on a frustum of a cone.

Part way along the stems 5 they are linked together by binding rings 6 and 7. A complete shuttlecock is constituted by the stem assembly 1 with striking member 12 attached and each of the stems carrying a vane 10.

Although not shown explicitly in the Figure, of course the stems are provided all around the circumference of the base at a regular spacing.

In a preferred embodiment, the stem assembly (less vanes) including the binding rings and base is produced by injection moulding. The vanes are separately manufactured by stamping out the appropriate shape from film material of appropriate thickness and density and these are attached to the individual stems of the moulded stem-assembly by adhesive, a welding process or by mechanical means or a combination of two or more of these means.

As indicated by dashed lines in Figure 1, a vane 10 is attached to the free end of each stem 5. Figure 2 shows vanes attached to three adjacent stems, the vanes being assembled on the stems so that they interleave by consecutively overlapping as shown in the Figure. This overlapping is continued by other vanes (not shown) all around the shuttlecock. The vanes may or may not be attached together where they overlap.

The attachment of each vane to its stem may be facilitated by the moulding-in of one or more flat areas on the stems referred to as 'spades' as shown in figure 3. The flat face of the spade faces outwards with respect to the axis of symmetry of the assembly of stems so that the vanes can be attached to the outer surfaces of the system of stems.

The stems and associated spades may be short (spade 8 in Figure 3(a)) or long (spade 9 in Figure 3 (b)) in that the stem and spade may or may not extend to the full length of the vane. The section through the stem may be of channel section, for instance as indicated by 11 in section AA' of Figure 3(c) to produce maximum stiffness in relation to weight per unit length.

A range of materials suitable for the stem assembly includes nylon, polyester (particularly polybutylene terephthalate), polypropylene and polycarbonate while that for the vanes includes nylon, polyester (particularly polyethylene terephthalate) and polypropylene. Blends of these and other materials may also be appropriate.

In certain circumstances the same basic material (eg polypropylene) may be used for both stems and vanes where slight differences in compound formulation and radical difference in production method of the components allow different qualities to be optimised.

For example, the same plastic material may be used for both stems and vanes but in the case of the stems the plastic may contain a small amount of reinforcing fibre, for example carbon fibre. Again, the stem system can be made by an injection moulding process but this process is not suitable for the vanes because of the extremely low thickness required for the latter (about O.lmm). The film material for the vanes can be produced by an extrusion and/or calendering process and this film may or may not be subject to axial orientation during processing. That is, plastic sheet may be stretched during manufacture along an axis to confer special directional properties by means of molecular alignment. In particular, bi-axial orientation is possible in which the film is stretched in two directions, usually at right angles.

The use of the same basic material for both vane and stem is advantageous in the case where welding is used to attach the vane to the stem, since it facilitates obtaining a good weld.

To summarise, the present invention can provide a hybrid plastic shuttlecock made of two different types of plastic for improved physical properties. A first type of plastic is used to form a stem assembly having a base to which a cork is attached and from which a plurality of stems extend. The "feathers" of the shuttlecock are provided by vanes attached to each of the stems, the vanes being formed of a second type of plastic. The stem assembly may be produced by injection moulding, and the vanes by stamping from film material. The same basic material may be used for both the stem assembly and the vanes, different properties being achieved by different processing and/or by reinforcing the stems with fibre.

Claims

CLAIMS 1. A shuttlecock comprising: a striking member; a stem assembly having a base to which the striking member is attached and a plurality of stems extending from the base; and a plurality of vanes, each of which is attached to a respective one of the stems; wherein the stem assembly and the vanes are made of plastics material, the plastics material used for the stem assembly having different properties from that used for the vanes.
2. A shuttlecock as claimed in claim 1, wherein the plastics material used for the stem assembly is a different basic material from that of the vanes.
3. A shuttlecock as claimed in claim 1, wherein the same basic material is used for the stem assembly and the vanes, but processed in different ways so as to give different physical properties to this stem assembly and the vanes.
4. A shuttlecock as claimed in claim 1, 2, or 3, wherein the stem assembly is an integral construction made by injection moulding.
5. A shuttlecock as claimed in claim 1, 2, 3, or 4, wherein the vanes are made by stamping from a film of plastics material.
6. A shuttlecock as claimed in any preceding claim, wherein the vanes are attached to the stems by adhesive.
7. A shuttlecock as claimed in any preceding claim, wherein the vanes are attached to the stems by welding.
8. A shuttlecock as claimed in any preceding claim, wherein the vanes are attached to the stems by mechanical means.
9. A shuttlecock as claimed in any preceding claim, wherein the base comprises an attachment member to which the striking member is attached, and a discshaped portion from which the stems extend in a frustoconical shape, the stems being linked part way along their lengths by at least one binding ring.
10. A shuttlecock as claimed in any preceding claim, wherein each of the stems has a spade portion formed part way along its length, for facilitating attachment of its respective vane.
11. A shuttlecock as claimed in any preceding claim, wherein each of the stems has a channel-shaped section.
12. A shuttlecock as claimed in any preceding claim, wherein the vanes overlap one with another when assembled on the stems.
13. A shuttlecock as claimed in claim 12, wherein the vanes are attached together where they overlap.
14. A shuttlecock as claimed in any preceding claim, wherein the stems incorporate reinforcing fibre as a minor component.
15. A shuttlecock, substantially as hereinbefore described with reference to the accompanying drawings.
16. A method of manufacturing a shuttlecock comprising the steps of: forming a stem assembly comprising a base and a plurality of stems extending from the base, by injection moulding of plastics material; forming a plurality of vanes by stamping from a film of plastics material; attaching one of the vanes to each of the stems, respectively; and attaching a striking member to the base.