GB2333723A

GB2333723A - Machines and methods suitable for use in disintegration of rubber tyres

Info

Publication number: GB2333723A
Application number: GB9801763A
Authority: GB
Inventors: Keith Trevor Rogers; Christopher Chatfield; Antony Lewis Farmer; David James Lewis
Original assignee: TECHNIC GROUP PLC
Current assignee: TECHNIC GROUP PLC
Priority date: 1998-01-28
Filing date: 1998-01-28
Publication date: 1999-08-04
Also published as: GB9801763D0

Abstract

A machine suitable for using in disintegration of rubber tyres comprising a support 12 for mounting a tyre 10 for rotation about a first axis A, extending in a direction from front to rear of the machine, first and second abrading tools 14 mounted for rotation about second and third axes parallel with the first axis and at opposite sides of the first axis, means mounting each tool for movement lengthwise of its axis of rotation to and fro between a retracted position and an advanced position wherein the retracted position of the first tool is at a rear portion of the machine, the retracted position of the second tool is at a front portion of the machine and the advanced positions are at a central portion between the front and rear portions of the machine, the advanced positions of the first and second tools overlapping when considered in a direction lengthwise of the first axis, the machine further comprising means for mounting the tools for movement towards and away from the first axis. A sensor 26 detects when the metal centre of the tyre is reached to terminate the abrasion action.

Description

MACHINES AND METHODS SUITABLE FOR USE IN DISINTEGRATION OF RUBBER TYRES This invention is concerned with machines and methods suitable for use in disintegration of rubber tyres and especially of solid rubber tyres for example solid rubber tyres used on fork lift trucks and certain earth moving equipment.

When tyres come to the end of their useful working life it is necessary to dispose of them and past practice has been to bury many worn-out tyres in suitable land-fill sites. This method of disposal is not regarded as being environmentally friendly and it is desirable to find ways of recycling the rubber compound from which the tyres are made. In order to recycle the rubber compound from used tyres, it is necessary to disintegrate the tyres or break them down reducing them into particles. It has been proposed to disintegrate tyres by forcing each tyre through a shredding machine consisting of two sets of interleaved cutting discs, each disc in a set being spaced by an equal amount from the next adjacent discs but this is a time consuming process and the shredded rubber produced by this means requires further treatment for most types of further use of the material. This known process is also slow and relatively expensive to carry out.

It has also been proposed to remove surface portions of pneumatic tyres to provide a suitable foundation for tyre retreading; and particulate material produced from this source can be recycled. However, equipment for removing the appropriate surface portions of a tyre for retreading is not suitable for completely disintegrating a solid tyre.

It is one of the various objects of the present invention to provide an improved machine suitable for use in the disintegration of solid rubber tyres.

It is another object of the present invention to provide a machine and method suitable for use in disintegrating rubber tyres having improved control of the disintegration operation.

The invention may be considered to provide, in one aspect, a machine suitable for using in disintegration of rubber tyres comprising a support for mounting a tyre for rotation about a first axis extending in a direction from front to rear of the machine, first and second tools mounted at opposite sides of the first axis means mounting each tool, for lengthwise movement parallel to the first axis, to and fro between a retracted position and an advanced position wherein the retracted position of the first tool is at a rear portion of the machine, the retracted position of the second tool is at a front portion of the machine and the advanced positions of both tools are at a central portion between the front and rear portions of the machine, the advanced positions of the first and second tools overlapping when considered in a direction lengthwise of the first axis, the machine further comprising means for mounting the tools for movement towards and away from the first axis.

Preferably, the tools are rotary tools mounted for rotation about second and third axes which are parallel with the first axis; thus the lengthwise movement of the first and second tools is along their respective axes of rotation. Preferably, both of the rotary tools comprise a body portion and at least one helical blade extending at least partly round the body portion; suitably each tool comprises a plurality of helical blades arranged in groups, each group subtending the same angle of less than 1800 about its axis of rotation with the blades in each group being parallel to the other blades in that group. Conveniently, the blades in each group are equally spaced one from the next and the spacing between the blades in each of the groups is the same. In a preferred embodiment the leading end of one group of blades is closely adjacent the trailing end of the next adjacent group of blades and the leading end of the said one group of blades is offset from the trailing end of the next adjacent group of blades by the spacing between adjacent blades in one of the groups, considered in the direction of the first axis.

In a preferred machine in accordance with the invention this means mounting the tools for said movement lengthwise of their axes of rotation comprises first and second carriages on which the first and second tools are mounted respectively, the first and second carriages being mounted on ways for said lengthwise movement, and drive means for propelling the carriages along the slideways. Any suitable drive means may be used, for example electric motors or pneumatic systems; however, the drive means preferably comprise hydraulic piston and cylinder arrangements, eg hydraulic rams, one associated with each of the first and second carriages.

Preferably, the means for mounting the abrading tools also comprises third and fourth carriages on which the first and second abrading tools are mounted, the third and fourth carriages conveniently mounting the abrading tools by means of first and second carriages as set out in the last preceding paragraph, the first and second carriages being mounted on the third and fourth carriages. The third and fourth carriages are mounted on ways for said movement towards and away from the first axis and the machine further comprises drive means for propelling the third and fourth carriages along the ways. Any suitable drive means may be used for this purpose for example electric or pneumatic motors, if necessary driving through suitable gearing mechanism; however, it is preferred that the drive means comprise hydraulic piston and cylinder arrangements, eg hydraulic rams, one associated with each slideway.

A machine in accordance with the invention suitably comprises means for adjusting the retracted position of each abrading tool and conveniently also adjusting the distance of travel between the retracted position and the advanced position. Preferably, the machine is so constructed and arranged that the abrading tools are moved from their retracted to the advanced positions in synchronism. Furthermore, in a preferred machine each abrading tool is also movable lengthwise of its axis of rotation to a rest position beyond its retracted position, considered in the direction when travelling from the advanced position towards the retracted position. In addition, a preferred machine in accordance with the invention comprises stop means arranged to stop the travel of the abrading tool beyond a maximum advanced position considered in the direction when travelling from the retracted position to the advanced position.

In a preferred machine in accordance with the invention including first and second carriages on which the abrading tools are mounted, the travel of the tools between the retracted and advanced positions is effected by moving the carriages appropriately along the ways on which the carriages are mounted. Where the drive means for the first and second carriages comprises hydraulic piston and cylinder arrangements, the various movements are controlled by control of the hydraulic piston and cylinder arrangements.

A machine in accordance with the invention comprising third and fourth carriages as referred to above, preferably comprises stop means limiting the movement of the third and fourth carriages between rest positions remote from the first axis and fully advanced positions, said stop means being arranged to return the third and fourth carriages to their rest positions after they have reached their fully advanced positions.

Conveniently a machine in accordance with the invention comprises means for setting a start position for each of the third and fourth carriages between their respective rest and fully advanced positions. The third and fourth carriages are, in use of the machine advanced from the rest positions, the start positions being equidistant from the first axis. The machine conveniently further comprises means for advancing the third and fourth carriages in synchronism from their start positions towards the first axis in equal step-wise increments. A preferred the machine comprises means for causing the third and fourth carriages to advance by one of said increments in synchronism with the to and fro movement of the first and second carriages, conveniently each time the first and second carriages return letter to their retracted positions or their advanced positions.

In another aspect, the invention may be considered to provide a machine suitable for use in disintegration of rubber tyres comprising a support for mounting a tyre for rotation about a first axis, at least one tool mounted for movement towards the first axis whereby to remove material from a tyre mounted on the support as the tyre is rotated about the first axis and a detector adapted to be in positioned adjacent a surface of a tyre mounted on the support and from which material is to be removed, the detector being arranged to detect metal within the tyre and to cause the tool to be removed from engagement with said surface of the tyre when the detector detects metal within the tyre adjacent the surface.

A machine in accordance with the invention which comprises a pair of tools, means mounting said tools for movement lengthwise of a first axis of rotation to and fro between retracted and advanced positions and means mounting the tools for movement towards and away from the first axis preferably also comprises a detector as set out in the last preceding paragraph. Where the machine comprises third and fourth carriages, the detector is conveniently arranged to cause the third and fourth carriages to return to their rest positions.

A detector of a machine in accordance with the invention preferably comprises a probe including a metal detector and the machine preferably comprises means for urging the probe into resilient engagement with a peripheral surface of a tyre mounted on the support of the machine which is to be operated on by the tools.

In another aspect the invention may be considered to provide a machine suitable for use in disintegration of annular rubber tyres comprising at least one tool and a support for a tyre comprising a chuck having at least three arms adapted to be introduced into the opening at the centre of the tyre, means for moving the arms outwardly to grip the tyre and means for rotating the chuck to thereby rotate a tyre gripped by the arms.

In yet another aspect the invention may be considered to provide a method of reducing a solid rubber tyre to particulate rubber material comprising mounting the tyre on a support and rotating the tyre about a first axis, intermittently moving the tools into engagement with a peripheral surface of the tyre whereby to remove rubber material in particulate form from the peripheral surface, the tools being disposed opposite one another at opposite sides of the first axis and being moved in synchronism in directions parallel with the first axis into engagement with the peripheral surface from retracted positions at opposite ends of the tyre considered in a direction parallel with the first axis and the tools being moved to advanced positions in which the tools overlap one another considered in the direction of the first axis whereby each tool operates on part of the width of the tyre, a first of the tools acting on a first part of the tyre closest to its retracted position and the second of the tools acting on the other part of the tyre closest to its retracted position and remote from the retracted position of the first tool and contiguous with the first part of the tyre so that the whole of the peripheral surface of the tyre is treated by the tools.

In another aspect the invention may be considered to provide a method of controlling a tyre disintegration machine for disintegration of solid rubber tyres to particular form by removing material from a peripheral surface of the tyre, in which a metal detector is positioned adjacent peripheral surface of the tyre and the detector is arranged to terminate removal of material from the surface when the detector detects metal within the tyre adjacent the surface.

Preferably in carrying out a method as set out in either one of the last two preceding paragraphs a machine in accordance with invention is used.

There now follows a detailed description to be read with reference to the accompanying drawings of a machine and method for disintegrating rubber tyres, embodying the invention. It will be realised that this machine and method have been selected for description to illustrate the invention by way of example.

In the accompanying drawings: Figure 1 is a front perspective view of a machine embodying the invention; Figure 2 is a left hand end view of the illustrative; Figure 3 is a rear view of the illustrative machine with parts broken away; Figure 4 is a front view of the illustrative machine, partly broken away; Figure 5 is a diagrammatic plan of the illustrative machine; Figure 6 is a hydraulic circuit diagram showing drive means for moving the third and fourth carriages; and Figure 7 is a hydraulic circuit diagram showing drive means for moving first and second carriages of the illustrative machine.

Figure 8 is a front view of a rasping tool suitable for use in the illustrative machine; Figure 8A is a fragmentary view showing part of a helical blade of the rasping tool indicated by reference I in Figure 8; and Figure 9 is a perspective view of a chuck of the illustrative machine.

There is described a machine for disintegration of rubber tyres 10 comprising a support 12 for mounting a tyre 10 for rotation about a first axis A extending in a direction from front to rear of the machine, a first tool 14 and a second tool 16 mounted for rotation about second and third axes B, C respectively, parallel with the first axis A and at opposite sides of the first axis (see Figure 5). The tools are mounted for movement in directions indicated by the arrows D, E, lengthwise of their axes B, C to and fro between a retracted position and an advanced position. The retracted position of the first tool 14 is at the rear portion of the machine and the retracted position of the second tool is at a front portion of the machine and the advanced positions of both tools 14, 16 are at a central region between the front and rear portions of the machine. The advanced positions of the first and second tools 14, 16 overlap when considered in a direction extending lengthwise of the first axis A. The tools are also mounted for movement towards and away from the first axis in a direction at right angles to the axis A generally indicated by the arrows F, G. The illustrative machine further comprises a detector 26 adapted to be positioned adjacent a surface 28 of the tyre 10 mounted on the support 12, the detector being arranged to detect metal within the tyre and to cause the tools 14, 16 to be removed from engagement with the surface 28 of the tyre when the detector 26 detects metal within the tyre adjacent the surface 28.

The illustrative machine further comprises a chuck 30 arranged to grip a tyre and rotate it about the axis A. The directions of rotation of the tools 14, 16 and of the chuck are shown by arrows on Figure 1.

The first and second tools 14, 16 used in the illustrative machine are rotary abrading tools of a general type which is commonly termed a rasping tool (or rasp) by those skilled in the art; the tools 14, 16 are described in detail hereinafter.

The illustrative machine includes a frame 32 on which are mounted the support 12 and first, second, third and fourth means 18, 20, 22, 24 mounting the tools 14, 16 for movement. The means 18, 22 mounting the first tool 14 are generally similar in construction and operation to the means 20, 24 mounting the second tool 16 and only the first means 18, 22 mounting the tool 14 will be described in detail.

The means 18 mounting the tool 14 for movement lengthwise of its axis B for movement to and fro in the direction indicated by the arrow D comprises a first carriage 34 and the means 22 for mounting the tool 14 for movement, indicated by the arrow F towards and away from the first axis A comprises a third carriage 36 on which the first carriage 34 is mounted. The third carriage 36 is mounted by bearings (not shown) on ways provided by parallel bars 38 secured to the frame.

Drive means provided by a hydraulic ram 40 is arranged to propel the third carriage 36 along the ways 38. The hydraulic circuit associated with the hydraulic piston and cylinder arrangement 40 is shown in Figure 6 and will be described in greater detail hereinafter.

The first carriage 34 is mounted by bearing means (not shown) on ways provided by parallel bars 42 secured to the third carriage 36, for movement lengthwise of the axis B in a direction indicated by the arrow D. The first carriage 34 is arranged to be moved by a hydraulic ram 44 comprising a hydraulic cylinder 46 secured to the third carriage 36 and driving the first carriage 34 through the piston rod. The relevant hydraulic circuit is shown in Figure 7 and will be described in more details subsequently.

An electric motor 48 is secured to the carriage 34 and its output shaft (not shown) lies along the axis B. The abrading tool 14 is secured to the output shaft and is thus mounted for rotation about the axis B.

The illustrative machine comprises means 50 for collecting particulate material removed from a tyre during operation of the machine.

This means comprises a hood 52 and a suction apparatus (not shown) connected to the hood 52 by flexible pipe 54 so that particulate rubber material abraded from the tyre 10 is sucked from the hood 52 through the pipe 54 by the suction apparatus, for collection in a receptacle (not shown) in a manner well-known in the art. The hood includes a shutter 56 arranged to be pivoted about the axis B by a piston and cylinder arrangement 58 mounted on the hood. The shutter can be pivoted between an open position in which it is shown in Figure 1 where the abrading tools 14, 16 are exposed for abrading operation on the tyre 10 to a closed position in which the shutter 56 shrouds the exposed part of the abrading tool 14, 16 to afford protection when the abrading tools 14, 16 are moved to their rest positions.

As mentioned previously, the construction and mounting of the second carriage 35 and fourth carriage 37 is similar to that of the first carriage 34 and third carriage 36 and these will not, therefore, be described in detail. However, the first and second carriages 34, 35 are arranged to travel in opposite directions in synchronism along their axes B, C, as discussed in more detail hereinafter.

The support 12 comprises a pillar 60 of the frame 32 which projects upwardly from a rear portion of the frame 32. The chuck 30 is mounted for rotation about the first axis A in bearings (not shown) carried by the pillar 60. The first, second and third axes A, B, C may be both parallel and coplanar. The illustrative machine further comprises an electric drive motor (not shown) mounted on the frame and arranged to drive the chuck 32 for rotation about the first axis A.

Although the motor driving the chuck 30 and the motors 48 are all electric motors in the illustrative machine, it will be understood that in a machine in accordance with the invention otherwise similar to the illustrative machine any suitable motor may be used, for example the motors may be hydraulic motors if desired.

The chuck 30 has three arms 62 mounted in a body portion 64 for sliding movement radially of the axis A. The arms are slidable in radial slots of inverted T cross-section and thus are retained captive to the body portion 64, whilst permitting the required radial sliding movement. The body 64 is drivingly connected to the electric motor for rotation about the axis A. The body 64 is mounted closely adjacent the pillar 60 and the arms 62 project forwardly from the body 64, parallel with the axis A for a distance sufficient to accommodate the wall-to-wall depth of all of the sizes of tyre intended to be disintegrated by the illustrative machine. Each of the arms 62 has an outwardly facing serrated surface 66 which is adapted to engage an inner surface of a tyre to be disintegrated when the arms 62 are introduced into the opening 68 at the centre of the tyre, as the arms 62 are moved outwardly away from the axis A. The arms each also comprise a stop finger 69 projecting outwardly beyond the serrated face 66 at a rear end of the arms, adjacent the body 64, the stop finger 69 providing a stop against which a rear edge portion of the tyre 10 to be disintegrated is arranged to abut to locate the tyre 10 lengthwise of the axis A.

The chuck 30 also comprises means, of a type known to the person skilled in the art, by which the arms 62 can be moved radially outwardly of the axis A to grip the tyre surface defining the opening 68 and clamp the tyre 10 to the rotary chuck 30 for rotation therewith and for retracting the arms inwardly towards the axis A to release the base 11 on which the rubber portion of the tyre 10 is built, from the chuck so that this base 11 may be removed after the rubber has been removed. The means for moving the arms 62 inwardly and outwardly conveniently operates using a camming action and can be locked with the arms gripping a tyre 10, in known manner.

Detector 26 (see Figure 4) is mounted on a bracket 70 which is upstanding from an upper rear portion of the pillar 60 and projects forwardly to overhang the position at which a tyre 10 is mounted on the chuck 30. The detector 26 comprises a probe 72 which is mounted on the bracket for upwards and downward movement radially to the axis A by means of a piston and cylinder arrangement (not shown) which is activated by an air solenoid valve when chuck rotation begins. The probe 72 is carried on a housing 74 which also mounts, at its lower end, a wheel 76.

The wheel is arranged to contact the peripheral surface 28 of a tyre when the housing 74 is lowered towards the axis A and the wheel runs on the surface 28 as the tyre 10 is rotated by rotation of the chuck 30. The wheel spacers probe 72 by a preselected fixed distance from the surface 28. The housing 74 is resiliently mounted so that it is urged into resilient engagement with the peripheral 28 thus to accommodate any irregularities in the surface 28. In the operation of the illustrative machine, as the surface 28 of the tyre 10 is abraded away by the tools 14, 16 the probe 72 is urged downwardly and maintained in resilient engagement with the surface 28.

The foundation of rubber tyres includes a metallic base layer 11 from which the rubber compound is built up. Thus, as the rubber compound of the tyre 10 is abraded away by the tools 14, 16, the diameter of the tyre being operated upon is gradually reduced and the probe 72 approaches more and more closely the axis A (and the metallic base layer on which the tyre is built). When the probe 72 detects metal within the tyre 10 adjacent the surface 28 a signal is passed to the control system of the illustrative machine and the probe 72 is raised out of engagement with the surface 28. By the same signal the hydraulic rams 40 are signalled to retract the third and fourth carriages 36, 37 to their rest positions, thus removing the abrading tools 14, 16 from engagement with the tyre 10.

Furthermore, the signal causes the rams 44 to retract the first and second carriages to their rest positions respectively at the rear and the front of the illustrative machine. The chuck 30 is then operated to retract the arms 62 radially inwardly towards the axis A and allow the remains of the tyre base (from which substantially all of the rubber compound has been removed) to be taken from the chuck.

In the correct operation of the illustrative machine it is necessary that the inward movement of the tools 14, 16 towards the first axis A is controlled so that the abrading tools 14, 16 operate correctly on the peripheral surface 28 of the tyre 10. It is also important that the to and fro motion of the tools 14, 16 between the advanced and retracted positions of the tools 14, 16 is also controlled carefully; in both cases the movements must be substantially symmetrical for most efficient operation.

In the illustrative machine, this is achieved by a combination of hydraulic and electrical means, as described hereafter, but other means may be used, if desired, for example electrical stepping motors and associated control systems might be used.

Turning now to the hydraulic system for moving the third and fourth carriages in the directions of the arrows F, G towards and away from the first axis A, reference is directed to Figure 6. The piston rods 41 of the hydraulic rams 40 are secured to the frame 32 of the illustrative machine and the cylinders of the rams 40 are secured to the third and fourth carriages 36, 37. Leading end portions of the cylinders 39 between the piston rods 41 and the pistons of the rams 40 are connected by a hydraulic fluid pipe 80. The hydraulic system further comprises a hydraulic power pack 82 supplying hydraulic fluid under pressure via a pipe 84 to a solenoid operated three way valve 86. The valve 86 is movable between three positions: a first position in which hydraulic fluid from the power pack 82 is connected via the pipe to a pipe 88 leading to the rear of the piston of the cylinder 39 mounted on the third carriage 36, a second position in which the valve 86 blocks hydraulic fluid from the pipe 84 passing through the valve 86, and a third position in which hydraulic fluid from the power pack is connected via the pipe 84 through the valve 86 to a hydraulic pipe 90 connected to the rear of the piston of the cylinder 39 mounted on the fourth carriage 37. When the solenoid valve 86 is in the first position admitting hydraulic fluid under pressure to the pipe 88, this drives the cylinder 39 (and thus the carriage 36 to which it is secured) towards the carriage 37. Admission of fluid under pressure through the pipe 88 and relative movement of the piston and the carriage 36 as specified causes fluid under pressure to be expelled from that cylinder 39 through the pipe 80, from the front of the piston, to enter the other cylinder 39 at the front and thus urge the other cylinder 39 (and the carriage 37 to which it is secured) towards the carriage 36. Fluid is expelled from the rear of the piston of the cylinder 39 mounted on the carriage 37 through the pipe 90 and the solenoid valve 86 back to the power pack 82.

As the rams 40 are identical the volume of fluid expelled from the ram mounted on the carriage 36 to the ram 40 mounted on the carriage 37 is such that each of the carriages 36, 37 moves the same incremental distance inwardly towards one another and towards the first axis A. The solenoid 86 is held in the first position to admit fluid under pressure to the pipe 88 for a preselected time following which the valve 86 is moved to the second position to prevent hydraulic fluid reaching either of the pipes 88, 90. The timer is triggered again subsequently at intermittent intervals to move the valve 86 to the first position and admit fluid under pressure to the pipe 88. This movement of the solenoid valve 86 is triggered by movement of the first carriage 18 each time the carriage 18 reaches its retracted position as discussed hereinafter. Thus each time the carriages 18, 20 reach their retracted positions the valve 86 is moved to its first position to cause the third and fourth carriages 36, 37 to be advanced by an incremental step. The length of the incremental step is determined by the time for which the solenoid valve 86 remains in its first position and this is governed by an adjustable timer (not shown) of the control system.

The timer is adjusted by the operator of the illustrative machine to give incremental steps of a desired length. The length of the incremental steps of the third and fourth carriages 36, 37 is a factor in determining the size of the particles removed from the surface 28 of the tyre 10 by the abrading tools 14, 16 in the operation of the illustrative machine.

The incremental movement of the carriages 36, 37 continues until the detector 26 detects presence of metal as hereinbefore described and signals the end of the operating cycle of the machine. The signal emitted by the detector 26 causes the solenoid valve 86 to move to its third position thus admitting fluid under pressure to the pipe 90 and causing the third and fourth carriages 36, 37 to be retracted away from each other and the first axis A. This retraction of the carriages 36, 37 continues until one of the carriages is detected by a photocell (not shown) which causes the solenoid valve 86 to move to its second position and thus cut off supply of hydraulic fluid under pressure to either of pipes 88, 90. The third and fourth carriages 36, 37 are thus stopped in their rest positions.

When a new tyre to be disintegrated is placed on to the chuck 30 and locked in place, the control system is adjusted so that when the machine is started, the solenoid valve 86 is moved to the first position to admit fluid under pressure to the pipe 88 and the timer is caused to hold the solenoid valve 86 in its first position until the carriages 36, 37 reach a start position in which they are equally spaced from the first axis A. The timer is adjusted according to the diameter of the tyre being operated upon so that when the carriages 36, 37 are in the start position the abrading tools 14, 16 are still spaced from the peripheral surface 28 of the tyre.

When the carriages 36, 37 reach the start position the timer signals the control system for the f

The control system for the first and second carriages is shown in Figure 7. The rams 44 by which the first and second carriages 34, 35 are moved are mounted on the third and fourth carriages 36, 37. Piston rods 45 of the rams 44 are connected to the corresponding one of the first and second carriages 34, 35. Portions of the cylinders 46 between the pistons (not shown) and the ends at which the piston rods project from the rams 44 are connected together by a hydraulic pipe 92. Hydraulic fluid is supplied to this control system by a power pack 94 through a pipe 96 and a second solenoid valve 98. The second solenoid valve 98 is movable between three positions: a first position in which hydraulic fluid under pressure is supplied from the power pack 94 through the pipe 96 and second solenoid valve 98 to a pipe 100 which is connected to the rear of the cylinder 44 which drives the second carriage 35 at the rear of the piston, a second position in which the solenoid valve 98 blocks hydraulic fluid from the power pack 94 passing through the second solenoid valve 98 and a third position in which hydraulic fluid from the power pack 94 passes through the pipe 96 and solenoid valve 98 to a pipe 102 connected to the cylinder which moves the first carriage 34 to the rear of the piston.

It can be seen that the pistons 44 are both mounted on the front of the illustrative machine. Thus, when fluid under pressure is admitted through the pipe 100 to the cylinder 44 which operates the second carriage 35, the second carriage 35 is caused to move rearwardly. As the carriage 35 moves rearwardly, fluid under pressure is expelled from the cylinder 44 which is moving the carriage 20 through the pipe 92 to the front of the cylinder 44 which operates the carriage 34 thus causing the piston rod 45 operating the first carriage 34 to be drawn back into the cylinder 44, pulling the first carriage 34 forwardly from its rest position. Fluid from the rear of the cylinder 44 driving the first carriage 34 is returned through the pipe 102 and solenoid valve 98 to the power pack 94. This movement of the piston rod secured to the carriage 34 draws the carriage 34 forwardly Thus, assuming that the first and second carriages 34, 35 start from their rest positions in which the first carriage 34 is at the rear of the machine and the second carriage 35 is at the front of the machine the carriages 34, 35 move from their rest positions towards one another.

When the illustrative machine is first started to operate on a tyre which is mounted on the chuck 30, this movement of the first and second carriages 34, 35, from their rest positions will be such as to move them to their retracted positions. These retracted positions are chosen according to the depth of the type between the sides of the tyre, considered in a direction lengthwise of the first axis A so that the first and second abrading tools 14, 16 are clear of the tyre 10. When the carriages 34, 35 reach their retracted positions under the control of a timer activated by initiating start of the machine, a second timer is activated and the solenoid valve 98 is held in the first position to continue movement of the carriages 34, 35 towards their advanced positions. The distance between the retracted and advanced positions is determined by the second timer and when the timer times out it operates the solenoid 98 to move it to the third position to admit fluid under pressure to the pipe 102, thus, to move the first carriage 34 rearwardly from its advanced position towards its retracted position and to move the second carriage 35 forwardly from its advanced position to its retracted position. Reciprocation of the carriages 34, 35 between their advanced and retracted positions continues until the detector 26 sends the signal terminating operation of the machine whereupon the carriages 34, 35 are returned to their rest positions by the rams 44.

Each time the second times out, terminating the return from the advanced to the retracted position at the retracted position, a signal is given starting the timer controlling movement of the third and fourth carriages 56, 37 to move the carriages by the ram 40 inwardly by one incremental step, as described previously.

The rams 44 are identical and thus the distances moved by the carriages 34, 35 between their advanced and retracted positions are the same for each of the carriages. The control system ensures that the carriages 34, 35 are reciprocated in synchronism.

As the carriages are reciprocated, the motors 48 are operated to rotate the abrading tools 14, 16 at high speed about their axes B, C and the wheel 10 supported on the chuck is rotated about the axis A. The abrading tools 14, 16 which are commonly referred to in the art as rasping tools contact the rubber compound of the tyre and, at each stroke, rasp rubber compound from the peripheral surface 28 of the tyre for collection by the suction means as described previously until the operation is terminated by the detector 26 as described previously.

When the carriages 34, 35 are in their advanced positions the tools are at their advanced positions at a central portion of the machine between the front and rear portions of the illustrative machine. The advanced positions of the first and second tools 14, 16 overlap when considered in a direction lengthwise of the first axis, by a small distance of a few millimetres conveniently about 10mm. Thus, in the operation of the illustrative machine the first tool operates to abrade approximately the half of the tyre closest to the rear of the machine (that is closest to the pillar 60) and the second abrading tool 16 operates to abrade the half of the tyre closest to the front of the illustrative machine (that is the half of the tyre remote from the pillar 60). Care is taken to ensure that the machine is adjusted so that the travel of the first and second tools 14, 16 overlaps slightly at the central portion of the illustrative machine. This central portion will correspond roughly with the centre of the tyre considered in the direction of the first axis A.

Operation of the illustrative machine in the way described ensures that both of the rasping tools 14, 16 operate effectively on the tyre and that the forces on the machine are substantially balanced. This arrangement allows rapid reduction of the rubber compound of solid tyres to a particulate form, the size of the particles being governed by adjustment of this machine, most significantly the incremental inward travel of the third and fourth carriages 36, 37 but also, to some extent, by the speed of rotation of the chuck 30, the abrading tools 14, 16 and also by the construction of the abrading tools.

Reference is now directed to Figures 8 in which is shown the rotary rasping tool 16; the tool 14 is generally similar except that it is intended to rotate in the opposite direction to the tool 16. As can be seen the tool comprises a body portion 104 on which are mounted a plurality of helical blades 106 which extend at least partly around the body portion 104, the blades being helical with respect to the axis of rotation C of the tool 16.

The helical blades 106 are arranged in groups 108a, 108b - 108n encompassing an arc subtending an angle of less than 1800 about its axis C of rotation. The blades 106 in each group are parallel to one another and equally spaced one from the next. There are five blades in each group in the rasping tools 14, 16 of the illustrative machine. As can be seen viewing Figures 8 and 9 the leading end 110 of one group 108a of blades is offset from the trailing end 112 of the next adjacent group 108b of blades by the spacing between adjacent blades in the groups.

The control systems of the illustrative machine can readily be adjusted to maximise the efficiency in operating on tyres of different diameters and depths considered in the direction of rotation of the tyre.

It is possible to reduce the rubber compound of solid tyres to particulate form in a very short time - for example a matter of four or five minutes for a relatively small solid tyre but longer for larger tyres.

The illustrative machine further comprises photocells arranged to detect the presence of the first and second carriages when they reach their rest positions, or should the carriages reach a maximum advanced position. The photocells are arranged to return the first and second carriages to their rest positions (from their maximum advanced positions), to send a signal to stop the operation of the illustrative machine and to retain them in their rest positions once the carriages 34, 35 have reached those positions.

Although the illustrative machine utilises abrading tools 14, 16 with helical blades arranged in groups, machines in accordance with the invention otherwise similar to the illustrative machine may use rotary abrading tools with different configurations. However, the tools of the configuration shown and described have been found to give good performance and produce relatively small sized particles which are more readily usable in a variety of recycling operations.

Although it is not preferred, machines otherwise generally similar to the illustrative machine may utilise abrading tools which are not rotatable. However, such fixed tools are slower and much less satisfactory in use in most circumstances.

The particulate material produced may be re-used for example in carpet backing or, indeed, in producing tyre compound.

Claims

CLAIMS 1. A machine suitable for using in disintegration of rubber tyres comprising a support for mounting a tyre for rotation about a first axis, extending in a direction from front to rear of the machine, first and second tools mounted at opposite sides of the first axis, means mounting each tool, for lengthwise movement parallel to the first axis to and fro between a retracted position and an advanced position wherein the retracted position of the first tool is at a rear portion of the machine, the retracted position of the second tool is at a front portion of the machine and the advanced positions of both tools are at a central portion between the front and rear portions of the machine, the advanced positions of the first and second tools overlapping when considered in a direction lengthwise of the first axis, the machine further comprising means for mounting the tools for movement towards and away from the first axis.
2. A machine according to claim 1 wherein the tools are rotary tools mounted for rotation about second and third axes parallel with the first axis.
3. A machine according to claim 2 wherein at least one of the tools comprises a body portion and a helical blade extending at least partly around the body portion.
4. A machine according to claim 3 comprising a plurality of blades, the blades being arranged in groups encompassing an arc subtending an angle of less than 1800 about the second or third axis, as appropriate, the blades in each group being parallel to the other blades in that group.
5. A machine according to claim 4 wherein the blades in a group are equally spaced one from the next.
6. A machine according to claim 5 wherein the spacing between the blades in each of the groups is the same.
7. A machine according to claim 6 wherein the leading end of one group of blades is offset from the trailing end of the next adjacent group of blades by the spacing between adjacent blades in one of the groups, considered in the direction of the axis of rotation of the tool.
8. A machine according to any one of the preceding claims wherein the means mounting the abrading tools for said movement lengthwise of the first axis comprises first and second carriages on which the first and second abrading tools are mounted respectively, the first and second carriages being mounted on ways for said movement in a direction lengthwise of the first axis and drive means for propelling the carriages along the ways.
9. A machine slideways according to claim 8 wherein the drive means comprises hydraulic rams, one associated with each carriage.
10. A machine according to any one of the preceding claims comprising means for adjusting the retracted position.
11. A machine according to claim 10 comprising means for adjusting the distance of travel between the retracted position and the advanced position.
12. A machine according to any one of the preceding claims so constructed and arranged that the abrading tools are moved from their retracted to their advanced positions in synchronism.
13. A machine according to any one of the preceding claims wherein each abrading tools is mounted for movement to a rest position beyond its retracted position considered in the direction when travelling from the advanced position towards the retracted position.
14. A machine according to any one of the preceding claims comprising stop means arranged to stop travel of the abrading tool beyond a maximum advanced position considered in the direction when travelling from the retracted position to the advanced position.
15. A machine according to any one of the preceding claims wherein said means for mounting the abrading tools for movement towards and away from the first axis comprises third and fourth carriages on which the first and second abrading tools are mounted respectively, the third and fourth carriages being mounted on ways for said movement towards and away from the first axis and drive means for propelling the third and fourth carriages along the ways.
16. A machine according to claim 8 wherein the means mounting the abrading tools for said movement parallel to the first axis comprises first and second carriages on which the first and second abrading tools are mounted respectively, and said means for mounting the abrading tools for movement towards and away from the first axis comprises third and fourth carriages which provide ways on which the first and second carriages are mounted for said movement parallel to the first axis, the third and fourth carriages being mounted on ways for said movement towards and away from the first axis, and comprising drive means for propelling the third and fourth carriages along their ways.
17. A machine according to either one of claims 15 and 16 wherein the drive means comprise hydraulic rams, one associated with each way.
18. A machine according to any one of claims 15 to 17 comprising stop means limiting the movement of the third and fourth carriages between rest positions remote from the first axis and fully advanced positions, said stop means including means to return the third and fourth carriages to their rest positions when they reach their fully advanced positions.
19. A machine according to claim 18 comprising means for setting a start position for each of the third and fourth carriages between their respective rest and fully advanced positions, to which the third and fourth carriages are, in use of the machine, advanced from their rest positions.
20. A machine according to claim 19 comprising means for advancing the third and fourth carriages from their start positions towards the first axis in synchronism in equal increments and means for causing the carriages to advance by one of said increments each time the first and second carriages return to either their retracted positions or their advanced positions.
21. A machine according to any one of claims 18 to 20 comprising a detector adapted to be positioned adjacent a surface of a tyre mounted on the support and from which material is to be removed, the detector being arranged to detect metal within the tyre and to cause the tool to be removed from engagement with said surface of the tyre when the detector detects metal within the tyre adjacent the surface, the detector being arranged to cause the carriages to return to their rest positions.
22. A machine according to anyone of claims 1 to 20 comprising a detector adapted to be in positioned adjacent a surface of a tyre mounted on the support and from which material is to be removed, the detector being arranged to detect metal within the tyre and to cause the tool to be removed. from engagement with said surface of the tyre when the detector detects metal within the tyre adjacent the surface.
23. A machine suitable for use in disintegration of rubber tyres comprising a support for mounting a tyre for rotation about a first axis, at least one tool mounted for movement towards the first axis whereby to remove material from a tyre mounted on the support as the tyre is rotated about the first axis and a detector adapted to be in positioned adjacent a surface of a tyre mounted on the support and from which material is to be removed, the detector being arranged to detect metal within the tyre and to cause the tool to be removed from engagement with said surface of the tyre when the detector detects metal within the tyre adjacent the surface.
24. A machine according to any one of claims 21 to 23 wherein the detector comprises a probe including a metal detector and means for urging the probe into resilient engagement with a peripheral surface of a tyre mounted on the support which is to be operated on by the tools.
25. A machine according to any one of the preceding claims comprising means for collecting material removed from the tyre during operation of the machine.
26. A machine according to any one of the preceding claims wherein the support comprises a chuck having at least three arms adapted to be introduced into the opening at the centre of the tyre, means for moving the arms outwardly to grip the tyre and means for rotating the chuck to thereby rotate a tyre gripped by the arms.
27. A machine suitable for use in disintegration of annular rubber tyres comprising at least one tool and a support for a tyre comprising a chuck having at least three arms adapted to be introduced into the opening at the centre of the tyre, means for moving the arms outwardly to grip the tyre and means for rotating the chuck to thereby rotate a tyre gripped by the arms.
28. A method of reducing a solid rubber tyre to particulate rubber material comprising mounting the tyre on a support and rotating the tyre about a first axis, intermittently moving the tools into engagement with a peripheral surface of the tyre whereby to remove rubber material in particulate form from the peripheral surface, the tools being disposed opposite one another at opposite sides of the first axis and being moved in synchronism in directions parallel with the first axis into engagement with the peripheral surface from retracted positions at opposite ends of the tyre considered in a direction parallel with the first axis and the tools being moved to advanced positions in which the tools overlap one another considered in the direction of the first axis whereby each tool operates on part of the width of the tyre, a first of the tools acting on a first part of the tyre closest to its retracted position and the second of the tools acting on the other part of the tyre closest to its retracted position and remote from the retracted position of the first tool and contiguous with the first part of the tyre so that the whole of the peripheral surface of the tyre is treated by the tools.
29. A method of controlling a tyre disintegration machine for disintegration of solid rubber tyres to particular form by removing material from a peripheral surface of the tyre, in which a metal detector is positioned adjacent peripheral surface of the tyre and the detector is arranged to terminate removal of material from the surface when the detector detects metal within the tyre adjacent the surface.
30. A method according to either one of claims 17 and 28 carried out using a machine according to any one of claims 1 to 6.