GB2145630A - Ball - Google Patents

Abstract

A ball for use in games such as cricket and baseball in which the ball 10 has a substantially smooth spherical shape and an array of indentations 12 disposed about an equatorial section 11 of the ball. The indentations 12 cause the ball to swing in flight enhancing its utility in the playing of the aforesaid games. The indentations may be provided in a raised band. <IMAGE>

Description

SPECIFICATION Improved ball The present invention relates to balls and more particularly to balls for playing games such as cricket, baseball and softball. In cricket and baseball, the player responsible for delivering the ball to the batter (i.e. the bowler or pitcher) often makes use of an aerodynamic effect to cause the ball to swing or deviate from its path as it approaches the batter.

In the case of the cricket ball, the aerodynamic effect is produced by a raised seam consisting of rows of stitching and the protuberance resulting from the joining of the lather hemispheres. In order to produce swing, the ball must be projected with the seam oriented at an angle to the direction of travel. Because the aerodynamic effect is sensitive to changes in the angle of the seam, it is necessary, in the interests of good swing, to keep the orientation of the seam reasonably constant during the progress of the ball towards the batsman. A high level of skill is required to project the ball in the correct orientation and to impart the degree of backspin necessary to stabilise the seam angle.

Baseballs and softballs do not have an aerodynamic seam, and swing must be developed by spinning the ball the so-called Magnus effect.

Not only is it difficult to obtain consistent swing with a conventional cricket ball for the reasons outlined, but the ball is subject to rapid reduction in aerodynamic effect with wear. In particular the seam tends to flatten rapidly with use and thus to become inefficient as an aerodynamic trip (see N. G.

Barton. "On the Swing of a Cricket Ball". Proc. R.

Soc. Lond.A379, 109--131(1982)).

It has been found by the present inventor that the disadvantages inherent in the seam of the traditional cricket ball as an aerodynamic trip may be overcome to a substantial extent by the use of a novel type of seam.

The present invention consists in a ball of a substantially smooth spherical shape and having around an equatorial section of the ball an array of indentations.

The seam row or rows of indentations in the surface of the ball has been found to produce an effect similar to that of the seam of a cricket ball. The indentations are preferably in the form of dimples, which resemble the indentations used on the surface of golf balls, and are'most preferably between 2.5 and 3.5mm in diameter and between 0,30 and 0.65mm in depth. There may be a single equatorial row of indentations or a plurality of such rows. Most preferably there are from three to five rows, each row being comprised of dimples as described above The equatorial section of the ball containing the rows of indentations preferably represents 20% or less of the diameter of the ball. In a conventional cricket ball the width of the section is preferably about 20mm.The indentations may have any desired pattern on the equatorial section of the ball. They may be in rows or in a random array. It is desirable, however, that the indentations be uniformly arrayed around the equatorial section in order to ensure that the aerodynamic effects produced by the ball in flight are uniform about the axis perpendicular to the plane of the equatorial section.

If desired, when used in the game of cricket, the seam section may be elevated, preferably by an amount of 0.4 to 0.75mm, above the surface of the ball. The addition of the elevated "trip" marginally increases the aerodynamic effect of the seam, and hence the degree to which the ball can be made to swing in flight.

Extensive wind tunnel testing has shown that the degree of swing obtained from balls using the new -seam can be made approximately equivalent to the -maximum swing of conventional cricket balls with pronounced seams, and is ordinarily greater than the swing obtained by imparting spin on baseballs and softballs. If desired for use in practice balls, the exact form of the seam can be varied to obtain considerably greater swing than is normal for cricket balls.

The swing obtained from balls using the new seam is much less sensitive to changes in seam angle than is the case with a conventional cricket ball: good swing may be obtained from seam angles ranging from 15 to 45". By comparison, the swing obtained from a conventional cricket ball decreases markedly beyond 30 of seam angle. It is thus easier for persons who have difficulty stabilizing the seam to obtain reasonable degrees of swing with balls using the new seam.

Because the seam is highly resistant to wear and flattening with use, swing is maintained in balls with the new seam over a longer period of use than is the case with conventional cricket balls.

It will be appreciated that the use of the expression "equatorial section" does not imply that the ball has any polarity other than that created by the presence of the section itself.

The ball is most preferably formed by injection moulding, or a like process, to provide an outer abrasion resistant synthetic plastic material.

If a hard ball is desired it is preferably formed with an abrasion resistant skin surrounding a solid sphere. The required weight may be obtained by the use of appropriate fillers in the inner sphere.

If a soft ball is desired, it is most preferably formed by an elastomeric abrasion resistant outer section surrounding an air core. If desired the pressure of the air may be raised in the course of manufacture, or a self-sealing teat or valve may be incorporated in the outer casing of the ball to permit adjustment of the air pressure during use of the ball.

If required, to obtain an appropriate degree of resilience and bounce, the outer section of the may be laminated from materials of different elastomeric properties and weights, with an abrasion resistant outer skin.

Preferably the soft balls according to this invention will bave a weight of from 92 to 120 grams for the game of cricket.

Hereinafter given by way of example only is a preferred embodiment of this invention described with reference to the accompanying drawing which shows an elevational view of a cricket ball according to this invention.

The ball 10 has a diameter of 69.5mm over the majority of its surface and is relatively smooth in those areas having that diameter. The ball is formed with a section 11 extending about an equator of the ball 10. The section 11 has a width of 20mm and is raised up from the surface of the ball by from 0.43 to 0.45mm. The section 11 is provided with four rows of dimples 12. Each dimple 12 is 3mm in diameter and has a depth of 0.58mm. The dimples 12 in each of the rows are so arranged that they are aligned on an axis angled to the plane of the equatorial section.

It will be recognised by persons skilled in the art that numerous variations and modifications may be made to the invention as described above without departing from the spirit or scope of the invention as broadly described.

Claims (10)

1. A ball of a substantially smooth spherical shape and having around an equatorial section of the ball an array of indentations.

2. A ball as claimed in claim 1 in which the indentations of the array are dimples having a diameter of from 2.5 to 3.5mm and a depth of from 0.3 to 0.65mm.

3. A ball as claimed in claim 1 or claim 2 in which the array of indentations comprises a plurality of rows of indentations each row lying parallel to an equatorial plane of the ball.

4. A ball as claimed in claim 4 in which there are from three to four rows of indentations.

5. A ball as claimed in any one of claims 1 to 4 in which the equatorial section of the ball occupies a width equal to no more than 20% of the diameter of the ball.

6. A ball as claimed in any one of claims 1 to 5 in which the equatorial section of the ball is raised up from the spherical surface of the ball.

7. A ball as claimed in claim 6 in which the equatorial section is raised up by an amount of from 0.4 to 0.75mm.

8. A ball as claimed in any one of claims 1 to 7 in which the ball is formed by injection moulding from a synthetic plastics material.

9. A ball as claimed in any one of claims 1 to 9 in which the ball has a weight of from 92 to 120 grams.

10. A ball substantially as hereinbefore described with reference to the accompanying drawing.