It is a well-known problem that vehicle tyres present a challenge for disposal.

This problem is especially the case with larger tyres such as those used for large earthmoving equipment.

This invention is directed to tyres of a type where a casing is substantially comprised of rubber (typically in the form of styrene butadiene rubber) from which tyres are substantially composed.

BACKGROUND ART The problem currently is that in any attempt to remove rubber or rubber-like materials from the body of the tyre, by for instance, grinding the material will firstly either cause the material to melt or as well burn.

Melting implicitly gums up any device being used as a removal instrument, and burning or smouldering changes the characteristics of the material so that apart from noxious fumes being issued, the material looses its flexibility or strength making any possibly recovered material of very little economic further value.

One present method of answering this problem is to freeze the tyre prior to using a removal tool.

The problem with this is that it firstly requires substantial overhead capital costs in order to have a freezing capacity for very large tyres and then to operate this for a long enough period to effect a solidification of the rubber or rubber-like material and then there is the actual cost of operating the freezer.

Finally however, the material that is currently being recovered from this method is in

the form of chips of a shape that do not always usefully assist in further use of the material in other applications.

An object of this invention is to propose an improved method for recovery of some tyre materials and also to propose an apparatus and a method of operating an apparatus, which provides for an improved removal procedure.

DISCLOSURE OF THE INVENTION In accordance with one aspect of this invention, although this need not necessarily be the broadest or indeed the only form of this, there is proposed a method of recovery which includes the steps of: effecting a removal of portions by use of a tool including an arcuate shaped blade and effecting a piece by piece removal of the tyre material by gouging pieces of the tyre with the tool from time to time.

In preference, the gouging is effected by a plurality of individual blades.

In preference, each blade is caused to engage with a gouging effect a pathway with respect to the tyre material at a speed below that which would cause melting by reason of frictional engagement or otherwise of the material being gouged.

In preference, there is provided a cutter-bar which includes a plurality of buttons each button being such as to have a perimeter curved or arcuate sharp edge thereby providing an arcuate shaped blade and such that respective buttons are positioned with their cutting edges located in an overlapping relationship along the axial direction of the cutter bar such that by rotation of the cutter-bar each of a set of the buttons in sequence engage and gouge portions of the tyre material.

In preference, for a tyre, the cutter-bar is held so that it will follow generally a pathway following a perimeter path of the tyre and be held in such a way that it will maintain pressure against an appropriately vulnerable portion of the tyre and be caused to follow a perimeter path while the cutter-bar is rotating about its own axis and thereby effecting the gouging action.

Cutter buttons of the type being considered in this application providing a circular gouging effect have never been used to the knowledge of the applicant for the recovery of tyre or tyre materials.

In preference, the relative shape of the cutting surfaces and the clearances relative to each cutter button and its position in relation to the cutter-bar and as it is being used, are selected so as to effect a useful gouging effect. It has been found that such clearance angles of cutting surfaces can be selected so as to be substantially more beneficial in some cases rather than others.

The invention can reside in the method of effecting recovery then of material from tyres and the invention can also reside in the recovered material which includes portions which are of curled shape. The term"curled shape"is used to identify the resulting material which is gouged by firstly a cutter-bar which is rotating and therefore passes through the material in a circular pathway, and also has an arcuate blade shape which is provided by in each case circular buttons which themselves then result in a length of recovered material also having a curved shape matching generally that of the diameter of each curved blade provided by the button.

Accordingly, the recovered material is curved in two ways namely, along its length and across its length.

A discovery of this invention is that materials recovered are very useful for applications, which have not hitherto been considered.

A first of these is a mat in which the material is held together in a matrix by a further binder that such that there are voids which allow for relative movement of the various pieces of recovered material.

Such an application as a mat using such recovered material is along the base of a playground for children so that the mats can be left for long periods outside because they comprise substantially long-lasting material recovered from tyres, but further, because of the individual curled shape, they are implicitly springy or additionally so, much more so than that which would be available because of the implicit nature of the material itself and this is very beneficial providing much more shock-absorbing effect for children who may fall onto the mat.

This then describes one application, but from this it is obvious that there are a number of other applications which could be equally beneficial.

To name but a few, the use of buffers which could surround roadside obstacles so as to reduce impact of motor vehicles against them.

Another application is to use such mats or other material on hard floors or concrete where others such as gymnasts might perform.

The location of such mats on the base and sides of low carrying trays where hitherto large rocks or other debris are loaded into the tray and without shock-absorption would effect denting and eventual substantial damage to the metallic nature of the tray.

Use of the material in other case can be used as refill in tyres and can either substantially or fully replace the pneumatic tube within a tyre.

For instance, a tyre that has been damaged can be subsequently filled with this material under a selected insertion pressure that such that there remains at least some interstices between the small curled particles.

In one application a tyre still on its rim has an access aperture cut either through the rim or even through a wall of the tyre and material the type of which we have previously discussed which is formed by this invention is then inserted to an extent that it is reasonably uniformly distributed throughout the inner part of the tyre and at a reasonably substantial pressure after which the axis aperture is closed by appropriate means.

The surprising discovery is that in such an application, the material continues to provide substantial resiliency for the use of the tyre again as a tyre for a vehicle, but at the same time, even a substantial weakening of portions of the tyre will not be so debilitating with respect to the continued performance of the tyre for vehicle support purposes.

In preference in another form the invention can be said to reside in a method of recovery of rubber or rubber like material from a vehicle tyre in the form of pieces the method including the step of gouging from the tyre each at least one piece where the gouging is effected by an arcuate blade which is pressed into the material with a sharp edge of the blade forward most and constrained to follow a circular path from a location of first engagement at an entry point at a surface of the material through a cutting path in the material to an exit point at a surface of the material.

In another preferred form method of recovery of rubber or rubber like material from

a vehicle tyre in the form of pieces the method including the step of gouging from the tyre at least one piece of the material where the gouging is effected by a circular blade which is pressed into the material with a sharp edge of a portion of the blade which is forward most being moved along a circular path from a location of first engagement at an entry point at a surface of the material through a cutting path in the material to an exit point at a surface of the material the speed of cutting movement of the blade being below that where a melting of the rubber or rubber-like material is caused.

In preference then the invention can also reside in each of these applications where it uses material recovered in the way described in connection with tyres.

For a better understanding of this invention it will now be described with reference to a preferred embodiment which shall be described with the assistance of drawings, it being understood however that it is not intended that the invention should necessarily be limited to any of the single features now described.

BRIEF DESCRIPTION OF THE DRAWINGS Accordingly this embodiment will be described with drawings in which: FIG. 1 is a perspective view of an apparatus supported with respect to a tyre where there is a downwardly depending cutter bar with a plurality of arcuate cutters and this is supported to be rotating about a perimeter path of the tyre; FIG. 2 is a side view of the type of tyre piece as it is cut; FIG. 3 is a cross-sectional view along the lines 3-3 in FIG. 2; FIG. 4 is a cross-sectional view of an arcuate button cutter of the type used in the embodiment; FIG. 5 is an end view of the cutter bar holding a plurality of the cutter buttons as in FIG. 4; FIG. 6 illustrates a portion of the tyre as it is being cut by the plurality of arcuate sharp blades of their respective buttons; FIG. 7 is a schematic view showing how each button on the cutter bar is offset one with respect to the other so that they provide an overlapping cutting pattern; FIG. 8 is a side elevation of a portion of the cutter bar showing how each of the cutter buttons is therefore offset to obtain the effect as in FIG. 7; FIG. 9 is a perspective view of two of the buttons held in a common radial position on the cutter bar; and

FIG. 10 is a further perspective view of a portion of the cutter bar again showing how several of the cutter buttons are relatively located with respect to cutter buttons at different radial positions.

BEST MODE FOR CARRYING OUT THE INVENTION Referring now in detail to the drawings, there is a cutter bar 1 which is supported by a frame 2 so as to be able to be rotated about firstly its own axis at 3 by drive means which are not specifically shown, and then to be driven around a perimeter path which is an inside path 4 of a tyre 5.

This is achieved by having the tyre 5 held in position on a base and having a central pivot 6 supporting a radial arm 7 to which the cutter bar 1 is supported and depends from, and then outside from this, a drive system 8 which includes wheels 9, one of which only is shown, which cause the radial arm 7 to rotate about the central axis of the stem 6 by being driven to engage the ground around an outside of the tyre.

From time to time, the position of a support block 10 to which the cutter bar is pivotally secured to, is changed so that there remains continuing outward pressure of the cutter bar against the inner surface of the tyre track 4.

This simply means then that the cutter bar is caused to rotate about its own axis 3 as it is then driven around the perimeter path and it is caused to push against the inner surface of the tyre material so that each of a plurality of cutter buttons will therefore effect a cutting action.

The result of this is to cause the cutting action to be a gauging action by a plurality of these cutter blades each of arcuate shape and such that each piece of rubber is snared and then gauged with a resultant piece of rubber which will take an acutely complex shape. This is shown in somewhat of an ideal arrangement in 11 in FIG. 2 and the cross-sectional view in FIG. 3.

In practice, the pieces of rubber come out somewhat more ragged, and there are some pieces longer than others and some that have slightly different arcuate cross- sectional shapes and so on.

The result, however, is that there are a number of cut tyre pieces shown typically at

11 which then can be collected for subsequent usage.

The tyre material from which most tyres are made these days use a material generally referred to as styrene butadiene rubber.

We have found that there is a limit to when such cutting can take place and a first of these is the temperature that can be reached by the material being cut.

Rubber is a most difficult material to cut because it is very vulnerable to melting at reasonably modest temperatures. If this occurs, then both any cutting action and subsequent use of any cutters becomes severely compromised thereafter.

In order to minimise this problem, the use of a plurality of individual cutter buttons has been of advantage, the angle of each blade as it approaches and cuts through the rubber, has been carefully selected to assist in minimising this effect, and finally, the speed with which the blade approaches and cuts through the rubber has also been carefully considered.

The speed itself is not a set velocity above which melting will occur and below which melting will not occur.

Clearly, surrounding temperatures will have a great deal to do with this speed, the particular formulation of the rubber itself will have more to do with this, the nature and size and sharpness of the individual blades will have further to do with this, and the extent of pressure that will be applied when the cutting is effected will also have more to do with this.

It is something that needs to be achieved by careful construction of the equipment as described and then trialed so that for an appropriate occasion, the velocity will then be selected appropriate to all of these conditions.

It has been discovered then that cutting of this form of rubber is feasible where the velocity of a cutting surface is selected so as to be below that which will cause a temperature to be reached which will cause the rubber or rubber like material to become sticky.

The result is that a piece of rubber can be cut which is curved in total side elevation and as well is curved in cross-section such as is shown at 12.

Both ends of the sliver or segment 11 will taper to a narrower point such as at 13.

This sliver while it is being cut from a solid piece of styrene butadiene rubber is because of this shape, if it is packed together with other pieces of similar shape or segments which have concave and convex surfaces, means that these particles tumbled or piled one on top of the other will capture a lot of air and will provide implicitly, substantial resiliency even if as is the case, from time to time, surfaces of various pieces of the rubber are joined and held together by some externally mixed binder.

Such a binder or glue can be latex rubber but such that such additional material does not of itself fill all of the space, therefore leaving many interstices which therefore provides for a substantial resilient support.

The way in which the segments or portions of rubber are gouged from the rubber of the tyre includes using a plurality of buttons each of which in this embodiment are shaped as is shown specifically in FIG. 4 which is a diametrical cross-section through such a button in which there is an annular blade at 15 supported by a body 16 which is secured to the cutter bar body 17 by a bolt shown at 18.

These buttons 14 can be selected in a variety of diameters from typically 6 millimeters in the one instance through to 16 millimeters in another.

The angle of the cutting blade which is a factor in effective gouging of the tyre casing material includes an undercut angle of 7 degrees as shown at 19 and an inner angle at 20 of 15 degrees.

These angles go toward assisting effective cutting and can be varied in our experience so far within about plus or minus 2 degrees in each case.

The cutter buttons can be referred to as indexed inserts and in one case can be purchased from"Kenna Metal"item k 313 which has been found to be effective.

If a plurality of these buttons 14 are supported so as to be outermost in relation to the diameter of the cutter bar body 17, then these can be offset particularly as is shown in both FIGS. 7 and 8 so that successive buttons can effectively then overlap each other with in the case of a 6 millimeter diameter button, a 4 millimeter separation centre to centre.

The results thus far established had been of very high significance indeed.

Tyres, especially those that are suitable for very large earthmoving equipment, that were previously disregarded to land fill, can now be economically and usefully used and slivers of material in the arcuate form described, can now be recovered in economic and significant quantities.

Some experiment has to take place in terms of the speed with which a cutter bar is used or a diameter of button is used or indeed the respective angles relating to the blade portion of this.

The recovery process has been found so far to create material which has of itself further economic value.