WO2000067856A1

WO2000067856A1 - A ball game plate and a method for its manufacture

Info

Publication number: WO2000067856A1
Application number: PCT/SE2000/000803
Authority: WO
Inventors: Mats Erlandson; Bengt Erlandson
Original assignee: Mats Erlandson; Bengt Erlandson
Priority date: 1999-05-07
Filing date: 2000-04-28
Publication date: 2000-11-16
Also published as: AU4789300A; SE518316C2; SE9901669D0; SE9901669L

Abstract

A ball game plate comprises an orthogonal parallelepipedic plate that has two mutually opposing and generally parallel main surfaces and that has a groove of constant cross-section extending transversely across one main surface. The plate is comprised of rubber granules consisting of rubber shredded from used vehicle tyres, and a cured binder of elastomeric nature. The plate is porous and the binder is hardened whilst the rubber granules are in a compressed state in a plate manufacturing mould. The plate is manufactured by feeding a mixture of rubber granules and binding agent into the mould and compressing said mixture to a given degree of compression and porosity. The binder is caused to harden whilst keeping the mixture under compression.

Description

A BALL GAME PLATE AND A METHOD FOR ITS MANUFACTURE

The present invention relates to a ball game plate or slab of the kind defined in the preamble of Claim 1.

The invention also relates to a method of producing such a ball plate in accordance with the preamble of the independent method Claim.

A ball game generally referred to as "gully ball" has been played in town and city environments for many years. This game often utilises an artificial water drainage gully that extends from the outlet of a rainwater downpipe and terminates at the edge of the sidewalk.

The game involves throwing a ball, for instance a tennis ball generally perpendicular to the longitudinal direction of the gully from a given distance therefrom. Points are won each time a player is successful in striking the distal wall of the gully and catching the ball as it rebounds.

The gully is, of course, a permanent installation and is often comprised of a series of sidewalk plates that each have a groove formed in its upper surface. In order to enable the game "gully ball" to be played in places other than on a sidewalk that includes drainage gullies of this kind, it has been proposed that plates that include such "gullies" are produced so that players of this game can transport the plates to any desired place and place them on some suitable supporting surface, for instance a lawn, a beach or some other surface. 2

The impracticability of manufacturing such a plate from stone material will be readily understood, one reason being the risk of damaging surrounding objects, transport vehicles and the like. On the other hand, it is important that the plate is accurately shaped, particularly with respect to the groove or "gully" and the upper surface of the plate, and consequently many materials can be considered initially unacceptable to this end. For instance, wood is an unsuitable material since the shape of a wooden plate will be changed by weather, wind and time.

Furthermore, the plate must have a relatively large mass in order for it to remain stationary on its supporting surface when the groove is struck by a ball.

A study of material suitable for the construction of such a ball game plate showed that rubber was the best candidate, and accordingly the plate was made from solid vulcanised rubber. The plate was manufactured by vulcanising a vulcanizable rubber mass in a generally orthogonal parallelepipedic shape that included a semi-circular groove.

It was surprisingly discovered, however, that a ball plate made of vulcanised rubber has a relatively low shape accuracy. Furthermore, it was found that the surface roughness of the plate could not be varied, but remained as it was when the shaped surfaces were first established, and that the hardness of the plate could only be varied by changing the basic composition of the material. It was also found that the plate could not be modified with respect to water permeability. O 00/67856

3

The object of the present invention is to provide a ball game plate with which the aforesaid drawbacks can be eliminated either totally or partially, both with respect to the actual plate and also with respect to its method of manufacture.

This object is achieved with the plate according to the independent Claim directed to the ball game plate. The object is also achieved with the independent Claim directed to a method of producing said plate.

Further embodiments of the invention are set forth in the accompanying dependent Claims .

The invention is based fundamentally on the concept of distributing uniformly in a rubber plate rubber granules that are mutually bonded by an elastic binding agent. The rubber granules may conveniently comprise shavings or particles taken from recycled rubber material, for instance from rubber vehicle tyres. Such shavings or granules can be formed by milling away the surface layer of used vehicle tyres, for instance. Alternatively, the shavings/granules can be formed by freezing the rubber material to a temperature of -170°C for instance and then crushing the frozen material to a convenient particle/granule size of about 3-5 mm. These rubber granules are mixed with a binding agent which when cured has elastomeric properties, and are fed into a divided mould or form and therein compressed to a chosen plate porosity, wherewith the binding agent is caused to harden whilst the plate is in its chosen state of compression.

The invention provides a plate which retains a shape accuracy that conforms to the shape of the mould or form in which the plate is moulded. The inventive game plate thus has a high degree of shape accuracy as opposed to a form-moulded and vulcanised solid rubber mass. By way of comparison, a vulcanised massive rubber plate often became distorted in its thickness direction (+/-3-5 mm at a thickness of 40 mm), probably as a result of stresses in the outer layers and possibly also due to varying degrees of vulcanisation.

The invention enables the surface roughness of the plate to be readily modified, conveniently by selection of the size and shape of the rubber granules and/or by appropriate modification of the compression/porosity of the material during curing of the plate.

The thickness of the plate is not a critical feature of the invention other than that the thickness of the material at the bottom of the groove shall be comparatively small so as to provide a thin part that will function as a type of hinge means between those parts of the plate that lie adjacent to the groove.

According to the invention, the rubber granules may comprise a relatively hard rubber (vehicle tyre rubber) , so that the plate will obtain a relatively high surface hardness and density, and so that the plate as a whole will be able to adapt to the underlying supporting surface and lie stably on said surface even should it contain small irregularities. It is important m this regard that the plate will lie stably on its supporting surface even when hit by the ball. The surface roughness of the inventive game plate can be readily regulated in one and the same form or mould, by appropriate selection of the size and/or hardness of the rubber granules, the extent to which the material is compressed in the mould, the degree of porosity (the amount of binding agent added). Thus, ball game plates of differing properties adapted to the wishes of the user can readily be produced in one and the same mould.

The invention will now be described in more detail by way of example and with reference to the accompanying drawing.

Fig. 1 is a schematic view of an inventive game plate.

Fig. 2 is an enlarged sectional view of part of the surface layer of the plate shown in Fig. 1.

Fig. 3 is a schematic illustration of apparatus for manufacturing an inventive plate.

Fig. 4 illustrates schematically the use of the inventive game plate.

The game plate illustrated in Fig. 1 is an orthogonal parallelepipedic plate whose top and bottom surfaces measure 3 x 3 dm. The plate has a thickness of 4 cm. Provided in the upper surface of the plate is a groove 2 which extends between two mutually opposite side edges of the plate 1 and divides said plate into two essentially identical parts. The groove 2 has a constant cross-section along its length, said cross-section having an arcuate shape with a radius of about As shown in Fig. 2, the plate 1 is made of rubber granules 11 that are bound together by a binding agent 12, wherewith the plate material also includes pores 13 that communicate with one another so as to enable fluid to pass through the plate.

The granules 11 are produced from used vehicle tyres or from some other rubber whose hardness corresponds substantially to that of vehicle tyres. The granules are produced by milling or by crushing rubber that has been frozen to a temperature of -170°C for instance. The granules 11 have a mean size of 3-5 mm. The binder 12 is a polyurethane binder. Uncured polyurethane 12 and granules 11 are thoroughly mixed together and the mixture fed into a mould or form (Fig. 3) that includes at least two parts 21; 22, 23 which together form a mould cavity that is filled with a mixture 26 consisting of granules 11 and binder 12. The mould parts 21; 22, 23, which define the outer shape of the plate 1, are brought together while compressing the mixture 26 such as to obtain a suitable porosity 13, whereafter the binder is allowed to cure or harden whilst keeping the material under the chosen degree of compression and with the chosen porosity. The mould 2 can be held closed by resting one main part 22, 23 of the mould on an underlying surface 7 while pressing the other main part 21 of said mould towards the surface 7 with the aid of a piston- cylinder device 8 , in a conventional manner. It will be seen that one main part of the mould has a patrix 20 whose shape corresponds to the shape of the groove 2.

Fig. 4 shows a player 31 throwing a ball 30 onto the plate 1 and striking the wall of the groove that lies distal from the player, said ball 30 rebounding back to the player 31 therewith enabling the player to catch the ball.

Claims

1. A ball game plate (1) that has a generally flat undersurface so that the plate will lie stably on a generally flat underlying support surface (7), wherein the plate has an upper surface that includes a groove (2) of rounded cross- sectional shape, and wherein the groove (2) is adapted for rebound of a ball (30) that is thrown obliquely to the upper surface of the plate (1) transversely of the longitudinal direction of said groove (2) and strikes the side wall of said groove that lies distal from the ball thrower, characterised in that the plate is comprised of an elastomeric material in the form of rubber granules (11) that are bonded together by an elastic binder (12).

2. A ball game plate according to Claim 1, characterised in that the rubber granules (11) are bonded together by the binder (12) whilst in a compressed state.

3. A ball game plate according to any one of Claims 1-3, characterised in that said material has a porosity in the form of open cells (13) between said granules.

4. A ball game plate according to any one of Claims 1-3, characterised in that the rubber granules (11) are comprised of recycled rubber material.

5. A method of manufacturing a ball game plate according to any one of Claims 1-4, wherein the plate (1) includes a groove (2), characterised by feeding a mixture of rubber granules (11) and a binder (12) into a mould or form that includes at least two mould parts that define the outer surfaces of said plate (1); bringing the mould parts (21; 22, 23) together such as to compress said mixture to a chosen porosity; and allowing the binder to cure or harden in the mould whilst keeping the mixture compressed.

6. A method according to Claim 5, characterised in that the rubber granules are comprised of pieces of recycled rubber material; and in that the binder is a polyurethane binder.

7. A method according to Claim 5 or 6 , characterised in that the surface roughness of the plate (1) is modified by selection of the size of the granules and/or the degree of compression of the mixture.

8. A method according to Claim 7, characterised in that the plate is permeable to fluid by virtue of having an open cell structure.