GB2026327A - Badminton rackets - Google Patents

Abstract

A throat piece of Y-shape is provided for a badminton racket. The ends of the head loop of the racket are secured one to each arm 11, 12 of the Y and the racket shaft is secured to the tail 14 of the Y. The included angle 2??? between the axes of the arms of the Y is from 110 DEG and 150 DEG . The arms and tail piece are preferably hollow with the head loop ends and the shaft respectively secured inside them. <IMAGE>

Description

SPECIFICATION Badminton rackets This invention relates to badminton rackets and particularly to rackets having a metal frame defining a head portion for stringing.

Metal-framed badminton rackets are well known and have found wide acceptance in the sport. One known form of such rackets has a tubular metal frame bent into a substantially oval loop to form the stringing area of the head, the ends of the frame being secured to the throat area of the racket inside a separate metal or plastics throat piece. The throat piece is designed to receive and secure the shaft of the racket. Thus the throat piece acts as a conventional T-piece joint and receives and effectively joins together the three parts.

The present invention provides an improved racket construction in the throat area whereby the rotational strength of the throat joint is improved. Also it may be possible that the balance point and centre of percussion, i.e.

sweet spot" of the racket can be brought to more advantageous positions.

Accordingly this invention provides a throat piece for a badminton racket, the throat piece being Y-shaped, the arms of the Y being to receive one end each of the head loop of the frame of the racket and the tail-piece of the Y being to receive the shaft of the racket, the included angle between the axes of the arms of the fork of the Y being from 110" to 150 .

The invention also provides a badminton racket having a metal frame in the form of a loop defining the head area, the ends of the loop being secured one to each of the arms of the fork of a Y-shaped throat piece, the tailpiece of the Y receiving the shaft of the racket and the included angle between the arms of the fork of the Y being from 110" to 150 .

The arms and tail-piece of the Y-piece are preferably hollow with the ends of the frame loop and the shaft being secured inside the arms and tail-piece respectively. However the arms and/or tail of the Y may be secured outside the ends of the frame loop and shaft respectively if desired and they may be solid.

It will be appreciated, however, that a hollow construction may be preferable for reasons of weight saving.

The throat piece is preferably of lightweight metal, e.g. aluminium or magnesium alloy but it may be of plastics material if desired. It is conveniently a one-piece construction, e.g.

casting or moulding but a drilled forging could also be utilised.

Although the included angle between the arms of the fork of the Y could in theory vary from a very small minimum value, say 10 to 15 , up to a maximum value of say 165 to 170 , we have found in practice that a maximum value of about 150 is desirable if a reasonable improvement in torsional strength of the throat joint is to be achieved. Similarly, at the other extreme, very low values of the included angle would result in a long, narrow extension of the head towards the handle end of the shaft. This would have the disadvantage of extra weight (since the shaft would effectively become a double shaft) and of causing extra tension in the extended frame because of the number of extra cross-strings that would be required.It might even prove necessay to utilise a "separator" throat piece between the double shafts so formed in order to prevent collapse of the frame. For these reasons, therefore, the present invention is limited to Y-pieces in which the included angle between the two arms of the fork of the Yisfrom 110 to 150 . 120 to 140 is a particularly preferred range and angles of, say, 130 to 132" are believed to be particularly acceptable in terms of strength and market acceptance.

It will be appreciated that the angles referred to above are measured between the axes of the arms of the fork of the Y. In other words the angle is measured from the longitudinal axis of each arm; the external angles and outside dimensions of the Y-piece are less important. Thus it is not necessary, for example where a hollow construction is used, that the arms of the Y have walls of uniform thickness, although this may well be convenient from the points of view of manufacture and weight. Thus, if desired, at one extreme the fork of the Y between the two arms could be filled in. However, in a badminton racket where weight is a problem, this could be a disadvantage.

The longitudinal axis of the tail of the Y will normally divide the included angle between the two arms of the fork of the Y into two substantially equal halves. (This half angle will for convenience hereafter be referred to as 'H'). In other words the shaft of the racket when fitted to the Y-piece lies along the longitudinal axis of the head.

The ends of the frame loop and the shaft of the racket are preferably secured to the Ypiece by glueing although other means, e.g.

rivets may be used, alternatively or additionally.

The preferred throat piece is made of magnesium alloy having a density of about 1.8 g/cc but other lightweight materials having densities from 1.2 to 3.0 g/cc may be used.

Aluminium alloys having densities from 2.6 to 2.8 g/cc are a preferred alternative. However, the lighter magnesium gives an advantage in that for a throat piece of a given weight, say 4.6 grammes, the magnesium throat piece can have longer arms and hence a greater surface area for glueing. Hence a stronger bond can be achieved between throat piece arms and frame.

Typical preferred throat pieces of the invention have weights in the range 4.5 to 4.7 grammes.

As indicated above, rackets of the present invention have greater resistance to torsional rotation in the throat area than rackets having a T-piece, this being a direct result of the angled fork of the Y bearing against and resisting rotation of the ends of the frame.

Thus rackets of the invention can be strengthened in the throat area without incurring any weight penalty.

Another advantage of utilising the angled fork of the Y-piece is effectively to lengthen the strung head of the racket by a small, but not insignificant, amount. For example, a conventional badminton racket has an overall length of about 26 inches. By bringing the ends of the frame head loop into the upwardly-extending arms of a Y instead of into the horizontally extending arms of a T-piece, the string surface of the head is extended towards the handle end of the racket by about 4 inch where 8 is 66 and by about i inch where a is 60 . This extension is for the same length and weight of head loop and hence enables the shaft to be shortened by the same amount without loss of overall length.A typical badminton shaft is of tubular steel having a greater wall thickness at the head end than the handle end. Hence the shortening of the shaft can be at its heaviest end and a conventional shaft weighing about 21 grammes can be reduced by about 12 grammes where #= 60 . This weight loss is very useful in the context of providing a very light but sufficiently strong racket.

The extension of the strung head of the racket described above also has the advantage of raising the "sweet spot" of the racket nearer the centre of the strung area. The sweet spot on a conventional racket is closer to the throat than to the geometric centre and a change to bring sweet spot and centre of geometry of stringing area nearer together is beneficial to the playing properties of the racket. Similarly the balance point can be moved nearer the longitudinal centre of the racket.

If desired the arms of the 'Y' may be provided with holes through them to provide stringing apertures for the central longitudinal strings of the racket. Usually there will only be one stringing aperture per arm, i.e. one pair of corresponding holes in the wall of each arm in the case of a hollow construction.

These apertures may be lined with hollow grommets, which may be of plastics material, e.g. nylon, to insulate the strings from the edges of the holes in the arm.

One embodiment of the invention is now described by way of example only with reference to the accompanying drawings in which: Figure 1 is a plan view of a Y-throat piece; Figure 2 is a section through the throat piece of Fig. 1; Figure 3 is a view, in the direction of arrow B of Fig. 2, of the opening of one of the arms of the Y-piece, and Figure 4 is a view in the direction of arrow A or Fig. 1.

The throat piece 10 is a one-piece magnesium alloy casting having a generally Y-shape.

The arms 11, 1 2 of the Y are hollow and are designed to receive one end each (not shown) of the metal head loop of a badminton racket frame. The bore 1 3 of each arm 11, 1 2 is sufficient to accommodate its loop end as a snug fit. The Y has a hollow tail piece 1 4 which has a parallel bore 1 5 to receive the shaft (not shown) of a badminton racket.

Arms 11, 1 2 each have a pair of corresponding holes 1 1 A, 11 B and 1 2A, 2B drilled through their wall. These holes are each of diameter sufficient to accommodate a hollow plastics rivet (not shown). When the racket frame is strung a longitudinal string can thereby pass through each of arms 11 and 1 2.

Arms 11 and 1 2 embrace an included angle XYZ of 132" so that the half angle a is 66 . The longitudinal axis of tail 14 divides angle XYZ into two equal sectors.

Both the shaft and the ends of the frame loop of a racket may be secured inside the tail and arms respectively of the Y-piece by glueing.

Claims (16)

1. A throat piece for a badminton racket, the throat piece being Y-shaped, the arms of the Y being to receive one end each of the head loop of the frame of the racket and the tail-piece of the Y being to receive the shaft of the racket, the included angle between the axes of the arms of the fork of the Y being from 110' to 150'.

2. A throat piece according to Claim 1, in which the arms and tail of the Y-piece are hollow.

3. A throat piece according to Claim 1 or 2, in which the included angle is from 120 to 140 .

4. A throat piece according to Claim 1, 2 or 3 in which the included angle is from 130 to 132".

5. A throat piece according to any one of the preceding claims, which is of aluminium alloy or magnesium alloy.

6. A throat piece according to any one of claims 1 to 4, which is of plastics material.

7. A throat piece according to any one of the preceding claims, which is a one-piece casting or moulding.

8. A throat piece according to any one of the preceding claims, which is made of a material having a density of from 1.2 to 3.0 g/cc.

9. A throat piece according to any one of the preceding claims, which weighs from 4.5 to 4.7 grammes.

10. A throat piece according to any one of the preceding claims, in which the longitudinal axis of the tail-piece divides the included angle between the longitudinal axes of the arms of the fork of the Y into two equal halves.

11. A throat piece substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

1 2. A badminton racket frame incorporating a throat piece according to any one of the preceding claims.

1 3. A badminton racket having a metal frame in the form of a loop defining the head area, the ends of the loop being secured one to each of the arms of the fork of a Y-shaped throat piece, the tail-piece of the Y receiving the shaft of the racket and the included angle between the arms of the fork of the Y being from 110' to 150'.

14. A badminton racket according to Claim 13, in which the ends of the loop of the frame and the shaft of the racket are secured inside the Y piece by glueing.

1 5. A badminton racket according to Claim 1 3 or 14, in which the arms of the fork of the Y have holes to allow longitudinal strings of the racket to pass through.

16. A badminton racket according to Claim 15, in which the holes are lined with hollow grommets of plastics material.