GB2447475A

GB2447475A - Tyre shredding apparatus

Info

Publication number: GB2447475A
Application number: GB0704861A
Authority: GB
Inventors: Liam Oldershaw
Original assignee: TYRE SHREDDERS UK Ltd
Current assignee: TYRE SHREDDERS UK Ltd
Priority date: 2007-03-14
Filing date: 2007-03-14
Publication date: 2008-09-17
Anticipated expiration: 2027-03-14
Also published as: GB2447475B; GB0704861D0

Abstract

A tyre shredding apparatus comprises two series of cutting discs 18 and two series of scavenger discs 16. Scavenger discs 16 help direct the material to be shredded towards the cutting discs 18. The first series of cutting discs 18 overlap the second series of cutting discs 18 in an axial direction. In order to allow the apparatus to shred more effectively a gap is provided between each of the overlapping discs in an axial direction. The apparatus may also be provided with a screen (20, fig.4) to prevent oversize material from leaving the apparatus. The two series of cutting discs 18 may be driven by separate drive means at different speeds and in opposite directions to one another.

Description

SHREDD ING APPARATUS

The present invention relates to tyre material shredding apparatus and methods of shredding tyre material to separate rubber from wire.

In a known tyre cutting arrangement shown schematically in Paynes 1 and 2 cuter discs 1 are mounted on parallel shafts 2. Broaching discs 3 are mounted on each side of the cutting discs on parallel shafts 4.

Tyres are fed to the cutting discs. In order to achieve optimum cutting, the cutting discs 1 are urged against each other at their adjacent circumferential extent. This achieves the best cutting action in the manner of a pair of scissors. Sharp edges are required.

These wear rapidly as the edges also have to cut the steel.

In addition, considerable power is required to slice through the rubber and tyre. All of the shafts are driven at the same speed by a common motor. Thus the motor has to have considerable power.

Rubber and wire separation by such an arrangement are not good. For instance, only 56% of the wire may be separated from the rubber.

It is an object of the present invention to attempt to overcome at least one of the above or other disadvantages.

According to one aspect of the present invention tyre material shredding apparatus includes at least a first and a second member rotatable about parallel axes each including a series of axially spaced shredders with the shredders of the first and second members overlapping each other in the direction between the axes of rotation of the first and second members and with a shredder from each of the first and second members being located, in an axial direction, between a shredder of the other member is characterised in that there is a gap in the axial direction between adjacent shredders of the first and second members.

According to a further aspect of the present invention a method of shredding tyre material to separate rubber from wire comprises passing the material through axially spaced shredders on first and second members rotating about parallel axes, each member including a series of axially spaced shredders with the shredders of the first and second members overlapping each other in the direction between the axes of rotation of the first and second members with a shredder from each of the first and second members being located in an axial direction between a shredder of the other is characterised in that shredding occurs in a gap in an axial direction between adjacent shredders of the first and second members to effect the shredding.

The present invention is defined in the claims and may

also be defined elsewhere in this specification.

The gap may be more than 0.2 or 0.4 or less than 2 or 1.8 or 1.4 or in the region of 1.2 or 1.1mm or in any range of any of these figures.

The first and second members may rotate at different rates of rotation such as within a range of 20 to 30 rpm or more than 20 or 22 or 24 or less than 30 or 28 or in any range of any of these figures.

The gap between adjacent shredders and broachers may be more than 2 or more than 2.5 or less than 5 or 4 or in the region of 3 mm or in any range of any of these figures. The ratio of the gap between adjacent shredders and broachers to the gap between adjacent shredders may be less than 5:0.2 or more than 1:1 or in the region of 3:1.

The distance between the screen and at least one shredder or, alternatively or additionally, at least one broacher may be less than 20 or 15 or more than 2 or in the region of 10 mm of in any range of any of these figures.

According to another aspect of the present invention a method of shredding tyre material to separate rubbers from wire causes passing the material through rotating members having spaced shredders to stretch and tear the rubber thereby causing the wire and rubber to separate.

The present invention includes any combination of the features of limitations.

The present invention may be carried into practice in various ways but one embodiment will now be described by way of example and with reference to the accompanying drawing in which:-Figure 3 is a schematic view of a tyre shredding system including a tyre supply station 10, a cutting station 12 and a tyre and wire separation station 14; Figure 4 is a side axial view of the cutting station 12; Figure 5 is a front, radial view of the cutting station; Figures 6 and 7 are a side and front view of a broaching disc 16 used in the cutting station; Figures 8 and 9 are a side and front view of a cutting disc 18; Figure 10 is a schematic view of a screen 20 used in the cutting station; and Figure 11 is a sectional view along the lines XI -XI of Figure 11.

In use, tyres 22 to be cut are placed onto a conveyor 24. The tyres fall onto a feed hopper 26 at the cutting station 12. The tyres may be partially cut before they are fed. The cutting station separates the tyres 22 into small pieces of rubber and wire which drop onto a conveyor 28. The conveyor 28 takes the cut rubber and wire to the separation station 14. At the separation station 14 an over band magnet 30 and a rare earth drum magnet 32 separate the rubber and the wire.

The cutting station 12 will now be described in more detail with reference to Figures 4 to 9. As shown in Figure 5, cutting discs or shredders 34 or 36 are mounted on parallel shafts 38 and 40. Broaching or scavenging discs 42 and 44 are mounted on parallel shafts 46 and 48.

Each disc includes a hub which abuts the hub of any adjacent disc on that shaft.

In the direction between the axes of the shredders the distance of the overlap 50 is between 7 and 15 and is preferably 10 mm.

In the axial direction, there is a degree of overlap between adjacent discs as indicated by the areas 48, where the cutting and broaching discs are adjacent and by the area 50, for the adjacent cutting discs. As seen in Figure 5, there are a series of discs 34, 36, 42, 44 along each shaft with all of the discs being spaced from adjacent ones.

The gap between adjacent cutting discs 34 and 36 is 0.6 mm but may be more or less such as more than 0.2 or 0.4 or less than 2 or less than 1.8 or less than 1.6 or less than 1.4 or in the region of 1.2 or 1.1mm or in any range between any given figures. As the cutting discs are spaced from each other the axial extent at the outer periphery need not be sharp and indeed ideally include a radius which may be 0.5 mm.

The gap between adjacent cutting discs and broaching discs is 3.1 mm but may be more than 2 or more than 2.5 or less than 5 or less than 4 mm or any range between any given figures.

The cutting disc shown in Figure 4 has a single hook 52 whereas that shown in Figures 8 and 9 includes two such hooks 54 diametrically opposed to each other. Either may be used. The hooks 54 have an outer surface on an arc having the same centre as the discs and leading and trailing recesses where they connect to the main portion of the disc. The hooks 52 shown in Figure 4 have an outer edge on an arc having the same centre as the disc. The leading edge includes a recess where it connects to the main portion of the disc and a trailing, rearwardly declining edge. Each broaching cutter includes four hooks 52 of the same profile or the hooks 52 of the cutting disc shown in Figure 4.

The cutting action will now be described. The tyres or pieces of tyres are caused to be cut or torn or reduced in size by passing between adjacent cutting discs. As this occurs the rubber is stretched and the separation of the wire, which is not elastic, is assisted. In this respect, as a rubber channel having a wire extending through it is opened up by the cutters the wire will come out of the channel, possibly as a result of the springy nature of the wire, even if the channel should later close.

The hooks 52 on the cutting discs assist in bringing pieces that are still too large, or which have not had sufficient separation, to be cut again either by passing these pieces to the broaching discs, which bring those pieces back on top of the cutting discs, or by dragging the pieces directly into the region between the cutting discs 34 and 36.

Adjacent cutter and broach disc shafts rotate in the same direction. Shafts 46 and 38 rotate in a clockwise direction and shafts 40 and 48 rotate in an anticlockwise direction.

Each shaft has its own motor and rotates at a different speed of between 23 to 28 rpm. For instance, the left hand broaching shaft may rotate at 23 rpm, the right hand broaching shaft at 24 rpm with the left hand cutter rotation at 28 rpm and the right hand one at 27 rpm. The speed of one or more motors may be varied continually or periodically if desired. This reduces the load on the motors as compared to conventional arrangements shown in Figures 1 and 2 that rotate at 30 to rpm and which are driven by a single motor at the same speed.

In addition, the adjacent surfaces in the present invention that effect the separation are always changing thus increasing the life of the parts. Further, if there is a part that is damaged for some reason, in conventional cutters those parts are destined to always cooperate on each rotation to continually effect a poor cut which is not the same with the present invention.

The current being driven by one or more motors is monitored and the rate of supply, such as the speed of the conveyor 24, can be altered to increase or decrease that rate.

Whilst the tyre material is being fed with rubber material water may be also be sprayed onto the cutting discs. This assists in lubricating the material and the discs.

The cutting station 12 also includes a screen 20. As shown in Figure 4, the screen is contoured in arcs around the centre of each shaft to leave a radial gap of 10mm between each hook 52 and the screen.

Whilst the hook may assist in compressing and pushing the pieces through the screen, when they are small enough they also clear pieces away from the top of the screen.

The screen includes openings 56 of 20 mm diameter at the surface that faces the hooks. These openings diverge outwardly to allow the rubber to enter the openings possibly under a slightly compressive force, and then spring outwardly to drop past the screen onto the conveyor 28, rather than spring out in an opening of constant size thereby blocking the sieve.

The conveyor 28 takes pieces of rubber and wire up to the separation station comprising the over band magnet 30 and the drum magnet 32, both of which are well known and thus will not be described in any great detail.

The over band magnet includes the magnet 58 itself which is fixed in position by means (not shown) above the conveyor 28. A conveyor 60 moves across the surface of the conveyor 28 at right angles thereto. The conveyor 60 includes outwardly facing flanges 62. Wire on the conveyor 28 is moved upwardly by the magnetic force of the magnet 58 and carried to the side of the conveyor 28.

When the wire is a sufficient distance from the magnetic force the wire falls off into a container (not shown) The drum magnet 32 includes axial extending magnets 64 on the inner circumferential surface. As the rubber moves over the end of the conveyor 28 it simply drops off. Any remaining wire remains attracted to the magnets 64 until they are sufficiently clear of the magnetic force at which time they too drop off into a container (not shown).

It is believed that up to 100% of the wire is separated from the rubber using the present apparatus.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification

(including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features

disclosed in this specification (including any

accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. Tyre material shredding apparatus including at least a first and a second member rotatable about parallel axes each including a series of axially spaced shredders with the shredders of the first and second members overlapping each other in the direction between the axes of rotation of the first and second members and with a shredder from each of the first and second members being located, in an axial direction, between a shredder of the other member characterised in that there is a gap in the axial direction between adjacent shredders of the first and second members.

2. Apparatus as claimed in claim 1 in which the gap includes the radially outermost extent of the shredders.

3. Apparatus as claimed in claims 1 or 2 in which the gap is more than 0.2 mm.

4. Apparatus as claimed in any preceding claim in which the gap is less than 2 mm.

5. Apparatus as claimed in any preceding claim in which at least a part of at least some shredders include a radially outer edge that is curved in the axial direction.

6. Apparatus as claimed in any preceding claim in which at least some shredders include an arcuate surface which arc has a radius the centre of which is the same as the axis of rotation of that shredder.

7. Apparatus as claimed in claim 6 in which at least some shredders include two arcuate surfaces of different radii the centre of which radii is the same as the axis of rotation of that shredder.

8. Apparatus as claimed in any preceding claim in which at least some shredders include at least one hook.

9. Apparatus as claimed in claim 8 in which the or each hook includes a rearwardly declining surface inwardly from the radially outermost extent of that hook.

10. Apparatus as claimed in any preceding claim in which the first and second members are arranged to rotate in opposite directions.

11. Apparatus as claimed in any preceding claim in which the first and second members rotate at different rates of rotation.

12. Apparatus as claimed in claim 10 or 11 including separate drives for the first and second members.

13. Apparatus as claimed in any preceding claim including control means arranged to monitor the degree of resistance to shredding.

14. Apparatus as claimed in claim 13 in which the control means are arranged to monitor at least one drive that causes rotation of at least one member.

15. Apparatus as claimed in claim 14 in which the control means are arranged to monitor the current of at least one drive.

16. Apparatus as claimed in claim 14 or 15 in which the cohtrol means are arranged to alter the rate of supply of tyre material to the shredders in response to the drive monitor.

17. Apparatus as claimed in any preceding claim including third and fourth members rotatable about parallel axis, which axes are parallel to the axes of the first and second axes, each member including a series of scavengers with the scavengers of each of the third and fourth members being arranged to cooperate with a different one of the first and second members whereby material is moved by the scavengers towards the overlap of the first and second members.

18. Apparatus as claimed in claim 17 including an overlap between the shredders and scavengers of the first and third and the second and fourth members in the direction between the axes of rotation of these members.

19. Apparatus as claimed in claim 18 including a gap between adjacent shredders and scavengers in the axial extent which gap is greater than the gap between adjacent shredders in that direction.

20. Apparatus as claimed in any of claims 17 to 19 whereby the speed of rotation of the third or fourth members is arranged to be different to the speed of rotation of the first or second members.

21. Apparatus as claimed in any of claims 17 to 20 in which the scavengers have any of the features of the shredders as referred to in any of claims 1 to 16.

22. Apparatus as claimed in any preceding claim including a screen arranged to limit the size of shredded rubber leaving the apparatus.

23. Type shredding apparatus including at least a first and second member rotatable about parallel axes each including a series of axially spaced shredders with the shredders of the first and second members overlapping each other at at least part of their peripheral extent in the direction between the axes of rotation of the first and second members and with a shredder from each of the first and second members being located, in an axial direction, between a shredder of the other member, the apparatus including a screen characterised in that the screen is located adjacent to the shredders.

24. Apparatus as claimed in claim 23 in which the shape of the screen follows the rotation of the shredder over part of the arc of rotation.

25. Apparatus as claimed in claim 23 or 24 in which the screen includes at least one arcuate section in the region of the shredder that the screen is adjacent to, which arc has the same axis as the axis of rotation of that shredder.

26. Apparatus as claimed in any of claims 23 to 25 in which the screen has a series of openings which have an increased cross-sectional area away from the surface that faces the shredder.

27. Tyre shredding apparatus as claimed in any of claims 23 to 26 in which the screen is included in apparatus having the features of any of claims 1 to 22.

28. Tyre material shredding apparatus including at least a first and a second member rotatable about parallel axes each including a series of axially spaced shredders with the shredders of the first and second members overlapping each other in the direction between the axes of rotation of the first and second members and with a shredder from each of the first and second members being located, in an axial direction, between a shredder of the other member characterised in that the speed of rotation of the members is arranged to be different.

29. Tyre shredding apparatus as claimed in claim 28 in which the apparatus is as claimed in any of claims 1 to 27.

30. Tyre material shredding apparatus including at least a first and a second member rotatable about parallel axes each including a series of axially spaced shredders with the shredders of the first and second members overlapping each other in the direction between the axes of rotation of the first and second members and with a shredder from each of the first and second members being located, in an axial direction, between a shredder of the other member with there being a gap between adjacent shredders at the radially outermost extent of the shredders and a screen, the screen having a shape which follows the rotational shape of the shredders over part of their arc of rotation.

31. Tyre shredding apparatus substantially as herein described with reference to and as shown in any of the accompanying drawings.

32. A method of shredding tyre material to separate rubber from wire comprising passing the material through a series of axially spaced shredders on first and second members rotating about parallel axes, with the shredders of the first and second members overlapping each other in the direction between the axes of rotation of the first and second members with a shredder from each of the first and second members being located in an axial direction between a shredder of the other characterised in that shredding is caused to occur in a gap in the axial direction between adjacent shredders of the first and second members to effect the separation.

33. A method as claimed in claim 32 comprising causing shredding to occur by stretching and tearing the rubber.

34. A method as claimed in claim 32 or 33 comprising causing the rate of rotation of one member to be less than the rate of rotation of the other member.

35. A method as claimed in claim 32 or 34 comprising causing each member to rotate with a separate drive.

36. A method as claimed in claim 32 or 35 comprising causing monitoring the effect required to drive at least one motor and varying the supply per unit of time of material to be shredded as a result of that monitoring.

37. A method as claimed in any of claim 32 to 36 comprising allowing shredded material to leave through a screen when the material has been shredded to below a size determined by the screen.

38. A method as claimed in claim 37 comprising causing shredded rubber to enter an opening having a first cross section in the screen of the surface of the screen under compression and then allowing the rubber to expand in the same opening spaced from the surface but having a greater cross-sectional area than that at the surface.

39. A method of shredding tyre material to separate rubber from wire causing passing the material through a series of axially spaced shredders on first and second members rotating about parallel axes, with the shredders of the first and second members overlapping each other in the direction between the axes of rotation of the first and second members with a shredder from each of the first and second members being located in an axial direction between a shredder of the other characterised in that rate of rotation of one member is less than the rate of rotation of the other.

40. A method as claimed in claim 39 causing monitoring the force required to rotate at least one member and varying the rate supply of material to be shredded as a result of that monitoring.

41. A method of shredding tyre material to separate rubber from wire causing passing the material through a series of axially spaced shredders of first and second members rotating about parallel axes, with the shredders of the first and second members overlapping each other in the direction between the axes of rotation of the first and second members with a shredder from each of the first and second members being located in an axial direction between a shredder of the other comprising allowing shredded rubber to leave through a screen by entering the screen under compression through an opening at the surface having a first cross-sectional area under pressure and then allowing the rubber to expand in the same opening spaced from the surface having a great crosssectional area than that of the opening at the surface.

42. A method of shredding tyre material substantially as herein described with reference to and as shown in any of the accompanying drawings.

43. A method of shredding tyre material as claimed in any of claims 32 to 42 when using apparatus as claimed in any of the claims 1 to 31.