GB2375054A

GB2375054A - Game balls

Info

Publication number: GB2375054A
Application number: GB0208042A
Authority: GB
Inventors: George Duncan Anderson
Original assignee: Mitre Sports International Ltd
Current assignee: Mitre Sports International Ltd
Priority date: 2001-04-19
Filing date: 2002-04-08
Publication date: 2002-11-06
Anticipated expiration: 2022-04-08
Also published as: ZA200202750B; GB0109650D0; GB0208042D0; AU784858B2; AU3434602A; HK1048961B; GB2375054B; NZ518297A; HK1048961A1

Abstract

Balls for sports use, comprising a set of panels (1) joined together edge-to-edge wherein one or more of said panels has at least one preformed flexion line (2) extending across the panel. In particular elongate sports balls (6) having a number of panels (1) joined together by seams, in which each panel (1) is longitudinally elongate so as to extend most or all the length of the ball (6) and has a plurality of flexion lines (2) extending longitudinally side by side along substantially or entirely the length of that panel. Also a method for producing such panels, and a method for producing sports balls from the panels.

Description

GAME BALLS This invention has to do with balls for sports use, and has particular relevance for elongate (oval) balls such as are used for playing rugby football and American football.

A conventional ball for rugby union consists of four generally leaf-shaped panels seamed to one another along their side edges and extending the full length of the ball. Usually each panel consists of a rubber outer layer backed by a fabric inner layer. An inflatable bladder occupies the ball interior. It is usual for the outer surface of the rubber layer to be marked with the manufacturer's trade mark and also embossed with a pimple pattern to improve grip. In this embossing procedure a layup of the fabric backing and the uncured rubber panel is pressed at raised temperature between an embossing plate having the pimple pattern and a flat base plate, curing the rubber and simultaneously joining it to the backing fabric.

What we now propose, in a game ball having a cover made from a set of panels joined together edge-to-edge, is to provide one or more panels with at least one preformed

flexion line extending across the panel. The flexion line may be provided by a line of reduced thickness of the panel material. Additionally or alternatively, the flexion line may involve a linear indentation of the

panel material on the reverse i. e. inner face. A , preferred form provides the flexion line as a line of reduced thickness provided by an indented groove only in the reverse face of the panel material, i. e. without any substantial groove or rib on the obverse (outer) face, at least in the untensioned (non-inflated) condition of the panel.

A functional benefit of this is in providing a line across which the panel is preferentially flexible, so that to some extent portions to either side of the line behave as separate panels. This means that for a given number of panels, a better contour of the ball shape can be achieved on inflation, since in general the larger the number of panels the better the conformity of the inflated ball to the desired shape (oval or spherical).

The use of numerous panels adds to the expense and in some games is restricted by rules. For example a rugby union ball is required to be made up from not more than four panels.

Preferably each panel has more than one flexion line, the lines preferably extending side by side. They may be parallel, or may converge towards ends of the panel. A preferred embodiment is an elongate ball such as a rugby

ball. In such a ball the preferred construction has the j or each flexion line extending generally longitudinally of the ball. In particular, where such a ball has panels which are elongate in the longitudinal direction of the ball-so that they extend most or all the length of the ball-the or each flexion line may extend substantially or entirely the length of that panel.

Thus, one preferred embodiment of the invention is an elongate ball with a cover sub-divided circumferentially (i. e. around the axis of the elongation) into a plurality of discrete panels joined together by seams, e. g. from three to ten panels, and in which each panel is longitudinally elongate so as to extend most or all of the length of the ball and has a set of flexion lines as described extending longitudinally and side by side.

Individual panels for any of the balls described above, preformed with the line (s) of flexion, are an independent aspect of the invention. Methods of making such panels, and methods of making the balls incorporating the

characteristic panels and/or the characteristic method of making the panels, are also aspects of the invention.

The panel material may in itself be conventional. For example a plastic or elastomeric impermeable outer layer can be used. Formations to create the flexion lines can exploit formability e. g. thermoformability of such material whether in the cured, set or uncured state. The preferred material is a rubber such as conventionally used. It is also preferred that the outer layer be backed on the inside by a textile layer and again this may be conventional. Usually the textile layer has a low flexural modulus and need not itself be modified at the line of flexion.

We mentioned above that a preferred way of making the flexion lines involves a linear indentation (groove) on the reverse of the panel material, more preferably without any corresponding surface feature on the obverse.

When a ball made using such panels is inflated, the relative recessing of the groove surfaces means that the pressure from the inner bladder acts primarily on the regions between the flexion lines, causing these regions to stand proud of the flexion lines on the ball exterior when the ball is fully inflated. With a series of

flexion lines this can create a characteristic ribbed surface contour which has several advantages. Firstly, it can improve grip by virtue of its own shape. Secondly it can help water to run off the ball, again improving

grip. Thirdly, depending on the disposition of the t flexion lines, it may improve the flight characteristic of the ball through the air e. g. by greater circularity and/or by enhancing turbulence within a boundary layer next to the ball surface; this is known to delay boundary layer breakaway at the rear of a body travelling through the air and hence reduce drag.

Because the flexion lines can improve the rounding of the ball profile in response to internal pressure, compared with conventional panels, the regularity of the ball shape can be improved and this improves consistency in kicking direction as well as flight characteristics.

An embodiment of the invention is now described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a plan view of the reverse surface of a panel for making a rugby ball; Fig. 2 is a section at II-II of Fig. 1 showing the layer construction of the panel;

Fig. 3 shows schematically portions of moulding plates used in making the panel; Fig. 4 is a side view of a made-up rugby ball; Fig. 5 is an end view of the same ball, and Fig. 6 is a plan view of the reverse of a panel showing an alternative disposition of flexion lines.

With reference initially to Figs. 1 and 2, a panel 1 for a rugby union football is generally leaf-shaped, with curved longitudinal boundaries 9 meeting at pointed ends 18. This shape is conventional for a four-panel ball.

Fig 2 is a cross-section showing how the panel is made up from an outer rubber layer 11 whose thickness-again conventionally-is between 0. 5mm and lmm and an inner layer 13 of rubberised fabric making a laminate about 2mm thick.

Fig. 3 shows schematically in cross-section a set of moulding plates used in making the panels 1. The moulding arrangement has a metal base plate 4 adapted to be sandwiched between a pair of embossing plates 5 to make a symmetrical arrangement. To make panels, an uncured rubber layer 11 and fabric layer 13 are laid up together between the base plate 4 and embossing plate 5, with the rubber layer 11 towards the embossing plate. A

similar layup is made on the other side of the base plate. Heat and pressure are then applied to cure the rubber layers, at the same time forming a integral bond between the fabric and rubber so that the fabric acts as a reinforcing and cushioning backing for the elastomer.

The surface of the embossing plate is formed with an array of small embossing indentations 51 which provide the outer surface of the rubber layer with innumerable minute protrusions giving better grip properties to the ball surface. So far, this is conventional. The distinctive feature is the provision of a series of parallel ribs 41 on the surface of the base plate. In this embodiment the ribs are spaced about 10mm apart and their height is up to about 1mm. The effect of these is to form a corresponding series of parallel grooves 15 in the reverse surface 14 of the rubber layer 11, the curing of the rubber making these grooves permanent. The fabric layer 13 follows the contour of these grooves 15, being bonded to the rubber surface, but need not itself be thinned at these regions.

Fig. 2 shows that the thickness of the rubber layer 11 is substantially reduced, e. g. by at least 50%, at these grooves 15. This creates flexion lines 2 at which the rubber material will flex relatively readily. Naturally

the relative increase in flexibility depends upon the depth of the groove relative to the rubber thickness. Because the rubber layer derives much of its structural integrity from the interior fabric backing it may be

possible to indent the grooves 15 substantially right , through the rubber layer 11. A panel with such a partial discontinuity is regarded herein as a single panel.

A rugby union football is made up from the panels in a generally conventional way, joining four of them together outside-in along seams 3 but leaving a small region unstitched, turning them rightside-out, inserting an inflation bladder and finally closing the cover by stitching the final portion.

The as-formed panel 1 has an outer surface 12 which is plain except for the pimpled grip pattern, i. e. it does not show the flexion lines 2. When the ball is inflated however the bladder acts initially on the lands between the grooves on the inner faces of the panels and pushes these relatively outwardly so that in the inflated ball (Figs. 4,5) the surface shows a pattern of bulging lands 19 between the flexion lines 2. The grip pattern 17 (shown only partially in Fig. 5, to avoid obscuring the figure) extends over the entire rubber surface. Because

the flexion lines 2 give preferential flexing, the ball 6 approximates more closely to a circular outline around its axis than a conventional ball. At the same time the characteristic ribbed exterior shape improves grip and handling.

The skilled person will appreciate that the parallel arrangement of grooves described above is not the only possibility. For example as shown in Fig. 6 the grooves might be curved so as to converge along the panel. Also, the grooves may not continue all the way to the extreme ends. In some kinds of ball there may be a discrete end panel e. g. a circular panel and the flexion lines described may terminate at or near the boundary with that end panel. Likewise the spacing of the flexion lines and their number may be varied.

Claims

CLAIMS: 1. A game ball comprising a set of panels joined together edge-to-edge, wherein one or more of said panels has at least one preformed flexion line extending across the panel.

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2. A game ball according to claim 1 wherein the or each flexion line is provided by a line of reduced thickness of the panel material and/or a linear indentation in the inner face of the panel material.
3. A game ball according to claim 2 wherein the or each flexion line is a line of reduced thickness of the panel material provided by a linear indentation groove in the inner face of the panel material.
4. A game ball according to any one of the above claims wherein each panel has a plurality of flexion lines extending side by side.
5. A game ball according to claim 4 wherein the plurality of flexion lines extend parallel to one another.
6. A game ball according to claim 4 or 5 wherein the plurality of flexion lines converge towards an end of the panel.
7. A game ball according to any one of the above claims which is an elongate ball wherein the or each flexion line extends generally longitudinally along the ball.

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8. An elongate game ball according to claim 7 in which the panels are elongate in the longitudinal direction of the ball.
9. An elongate game ball according to claim 7 or 8 wherein the panels extend most or all the length of the

ball, and the or each flexion line extends substantially I or entirely the length of the respective panel.
10. An elongate game ball according to any one of claims 1 to 6 having three to ten panels joined together by seams, in which each panel is longitudinally elongate so as to extend most or all the length of the ball and has a plurality of flexion lines extending longitudinally side by side along substantially or entirely the length of that panel.
11. A game ball according to any one of claims 1 to 10 wherein each panel has a plastic or elastomeric impermeable outer layer and a textile inner layer.
12. A game ball according to claim 11 wherein each panel has a rubber outer layer and a rubberised fabric inner layer.
13. A game ball according to anyone of the preceding claims which is a rugby ball.
14. A game ball panel having at least one preformed flexion line extending across the panel.
15. A game ball panel according to claim 14 wherein the or each flexion line is provided by a line of reduced

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thickness of the panel material and/or a linear indentation in the inner face of the panel material.
16. A game ball panel according to claim 15 wherein the or each flexion line is a line of reduced thickness of the panel material provided by a linear indentation groove in the inner face of the panel material.
17. A game ball panel according to any one of claims 14 to 16 wherein the panel has a plurality of flexion lines extending side by side.
18. A game ball panel according to claim 17 wherein the plurality of flexion lines extend parallel to one another.
19. A game ball panel according to claim 17 or 18 wherein the plurality of flexion lines converge towards at an end of the panel.
20. A panel according to any one of claims 14 to 19 having a plastic or elastomeric impermeable outer layer and a textile inner layer.
21. A panel according to claim 20 having a rubber outer layer and a rubberised fabric inner layer.
22. A method for the production of a panel for a game ball as defined in any one of claims 1 to 13 comprising providing a first plate having at least one rib on its surface and a second plate; placing a panel blank between the first and second plates; applying heat and pressure so that the rib forms the flexion line.

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23. A method for the production of a game ball comprising joining together edge-to-edge a plurality of panels as defined in any one of claims 14 to 21.