GB2136695A - Badminton racket - Google Patents

Abstract

A badminton racket includes a tubular frame comprising a shaft and a head loop, in which the area defined by the outer perimeter of the head loop, i.e. the stringing area inside the head loop and the tubular loop itself, is from 280 to 360 sq. cms. Conventional-length shafts may be used resulting in racket frames about 2 cm shorter and 2 to 4 g lighter than conventional frames and with improved balance and 'feel' properties. The tubular frame may be of metal, e.g. steel or aluminium alloy, or of fibre-reinforced plastics material.

Description

SPECIFICATION Badminton rackets This invention relates to badminton rackets and particularly to tubular frames therefor.

Tubular metal-framed badminton rackets have been popular for many years and have largely, aithough not entirely, replaced the traditional wooden-framed rackets. One principal reason for this is that the tubular metal-framed rackets are lighter in weight. A badminton racket frame is required to be as light as possible consistent with adequate strength and in recent years much development work has been directed to the saving of weight without incurring other penalties in the playing properties and strength of the racket.

A conventional metal badminton racket has an overall length of about 66 to 67 cm, which is usually made up of a shaft and handle of about 41 to 42 cm. length and a head loop of about 380 sq.cm, or more, i.e.

including the frame. We have now found that significant advantages can be obtained by producing a racket with a head size of rather less than conventional size.

The invention provides, therefore, a tubular frame for a badminton racket, the frame having a shaft and a head loop, in which the area defined by the outer perimeter of the head loop is from 280 to 360 sq. cms.

Preferably this head loop area is from 290 to 350, especially 300 to 330 sq.cms.

It will be appreciated that the area defined by the outer perimeter of the head loop area comprises the stringing area inside the head loop plus the tubular loop itself.

The frame is preferably of tubular steel or aluminium alloy and has a weight of from 86 g to 90 g compared with weights of from 90 g upwards for conventional metal rackets, i.e. for the completed unstrung frame.

Alternatively the tubular frame may be of fibre-reinforced plastics material. It may be of thermoplastics, e.g. nylon, or thermosetting, e.g. polyester, type and glass, carbon or boron fibres, or mixtures thereof, can be used as the reinforcing medium.

It will normally be found convenient to use conventional shafts and handles so that the overall length of rackets of the invention will be shorter than for conventional rackets by any difference in length of head. This may be for example about 2 cms. so that the overall length is for example 64 to 65 cms.

The frame may be formed and finished by any suitable methods and has the advantage when of tubular metal of being able to be made by the now conventional techniques and materials for metal-framed badminton rackets. Thus conventional tube-forming and joining techniques and conventional stringing hole formation and stringing techniques may be utilised as may the use of grommets, finishing operations and the like.

Where a separate throat-piece is used to join head and shaft, e.g. the conventionally-used T-piece, it may be necessary to estimate the area occupied by the head loop in the vicinity of the throat piece, e.g. by a notional extension of the two ends of the head loop. However, the amount of variation will be small relative to the total area and hence of no great consequence.

Rackets made according to the invention have been found to have surprisingly good playing properties.

For example, the wind-resistance to the racket during acceleration tests has been found to be reduced by from 10 to 25%.

Furthermore a weight saving of about 2 to 4 g for the head is complemented by a saving in string weight of about 1 g. This total weight saving is very significant and in conjunction with the decreased wind-resistance enables-the racket to be accelerated faster into the stroke by players. This is a particularly advantageous property for a badminton racket.

The novel dimensions of rackets of the invention also result in the moving of the balance point of the racket nearer the handle end of the shaft when compared for a conventional racket. This movement can be for example from 1/2 to 1 cm. This balance point change results in a racket of better balance and "feel" to the player.

Another advantage of racket frames of the invention is that they can be strung at greater tension than conventional rackets as they have a greater ability to resist distortion. This enables greater power to be generated which is advantageous for the stronger players.

In addition to having physically measurable advantages over conventional-sized rackets, rackets of the invention have proved surprisingly acceptable to players. Use of a racket depends on a complex combination of characteristics in which appearance and 'feel' play a large part. Despite their smaller size, we have found that rackets of the invention do not deter players from playing shots with confidence, although it is believed that this confidence can diminish as the racket head gets even smaller so that head sizes below those specified above are not intended to be part of the present invention.

The invention is further illustrated by the following example.

A racket frame of the invention was made from conventionally-used aluminium tube in the form of a head loop of area 324.25 sq.cms. attached by a conventional T-piece connector to a conventional shaft and handle giving a frame of overall length 64.6 cm.

The head of the racket frame was then subjected to comparative wind resistance tests with the head of a leading commercially available conventional racket namley the Carlton 3.7. This had a head loop area of 397.8 sq.cm. and an overall length of 66.05 cm. The shafts and handles were removed from the rackets and the heads attached in turn to a spindle via their T-piece connectors. The spindle was rotated at a speed such that the head traveis at the speed similar to that used in a powerful serve or smash hit.

By using a wattmeter the power being used by the electric motor was measured. The first measurement to be taken was that drawn by the motor when running light, so that this would be deducted from the other readings to determine the powerto drive the racket.

The test rackets were then fitted so that the power to drive them could be measured.

The 3.7 head was first used and was taken as standard.

Thus, reiative to standard - the power to drive a racket head is given by: PS-PT x 100% PS PT = Power to drive test racket PS = Power to drive standard racket Power required to drive the test spindle without racket is: 190W Power required to drive standard racket head was: 525 - 190 = 335W Power required to drive racket head of invention was: 456 - 190 = 266W Relationship between standard and small head of invention was: 335-266 x 100 20 6% 335 i.e. head of invention requires 20.6% less power.

As we know the power consumed and the velocity, it is possible to calculate the wind resistance at that speed.

The velocity at the centre of the racket head was 34 metre per second (M/S) and given that 1 watt = 1 newton metre/second (1 NM/S): Standard racket head: Wind load = 335 N 34 = 9.87 Newtons Similarly: head of invention: wind load = 7.82 N It can be seen from the above that the racket head of the invention had considerably reduced wind resistance. Rackets of the invention were also subjected to player tests which rated them as "excellent" and "considerably improved" in playing properties such as power and manoeuvrability.

Claims (10)

1. A badminton racket frame of tubular construction, the frame comprising a shaft and a head loop, in which the area defined by the outer perimeter of the head loop is from 280 to 360 square centimetres.

2. A badminton racket frame according to Claim 1, in which the tubular frame is of metal.

3. A badminton racket frame according to Claim 2, in which the frame is of steel or an aluminium alloy.

4. A badminton racket frame according to Claim 1, in which the tubular frame is of reinforced plastics material.

5. A badminton racket frame according to Claim 4, in which the reinforcement is of glass, carbon or boron fibres or blends thereof.

6. A badminton racket frame according to any one of Claims 1 to 5, in which said area is from 290 to 350 square centimetres.

7. A badminton racket frame according to Claim 6, in which said area is from 300 to 330 square centimetres.

8. A badminton racket frame according to any one of the preceding Claims, in which the frame weighs from 86 to 90 g.

9. A badminton racket frame according to any one of the preceding claims, which has an overall length of 64 to 65 cms.

10. A badminton racket frame according to Claim 9, in which the length of the shaft and handle is 41 to 42 cms.