GB2288346A

GB2288346A - Machine for shredding brush

Info

Publication number: GB2288346A
Application number: GB9505298A
Authority: GB
Inventors: Henry Brain; Andrew Frank; Kenneth Lindsay; John Mcauley
Original assignee: HARPER ADAMS ENTERPRISES LIMIT
Current assignee: HARPER ADAMS ENTERPRISES LIMIT
Priority date: 1994-03-16
Filing date: 1995-03-16
Publication date: 1995-10-18
Also published as: GB9405125D0; GB9505298D0

Abstract

A wood shredder (1) has a flywheel (22) mounted on an axle (10), the flywheel carrying L-section paddles (24) which in use urge brushwood fed down a feed chute (30) against the cutting edge of a knife (28). Because there is a flywheel the machine rotates at much slower speeds than conventional machines, and this results in there being less noise produced by the shredding machine. Furthermore, because the cutting blade is stationary it is easier to maintain. The axle (10) is usually connected in use to the power take-off of a tractor. The cutting machine usually has a support frame (16) which has a three-point linkage (40). <IMAGE>

Description

MACHINES FOR SHREDDING WOOD, GARDEN WASTE, AND THE LIKE This invention relates to machines for shredding or chopping wood, such as branches or twigs, garden waste, and other things to be shredded.

One known kind of machine for shredding brushwood, branches and other garden waste has several thin knife blades that rotate at very high speed (several thousand rpm) so as to enable the rotating knife blades to cut through even quite substantial branches or twigs. The processed material produced by such wood shredders is often used as a mulch of wood chippings to keep down weeds in gardens and public places.

According to a first aspect of the invention we provide a wood shredding machine having a rotating branch-engaging component which in use contacts branches or other material introduced into a cutting zone of the machine so as to cause them to be cut, broken or shredded, and which has flywheel means operatively coupled to said rotating component.

We have appreciated that the prior art arrangement has a disadvantage that has hitherto simply been accepted as inevitable: it is noisy. Because the prior art arrangement has a thin blade with a relatively small rotational moment of inertia it needs to be rotated at high speed in order to give it sufficient kinetic energy and momentum to cut through thicker branches. Its high speed of rotation makes it noisy in use. Many people consider this type of shredding machine too noisy for use in built-up areas such as parks or roads outside houses because of the disturbance to local people. At present branches from trees that have been pruned, or blown down, in such areas are loaded onto lorries and driven to a remote site for shredding. The resultant wood chippings are then, in some extreme cases, transported back to the same site from which the branches were collected and used as a mulch.This is clearly, with hindsight, wasteful of time and money.

We have found that if we use flywheel means adapted to have a higher rotational moment we can get satisfactory results if we rotate the branch-engaging component slower than is conventional. This has surprisingly made the machine quieter, which in turn allows us to shred mulch in situ, near where the branches lie. Even if the mulch or chippings are transported away they occupy much less space than a main branch with many side branches and twigs (which is mostly air).

Preferably the rotating branch-engaging component does not have a sharp, thin, edge which may be blunted or broken.

We may rotate the rotating component so that it has sufficient momentum and energy that it does not need a sharp cutting edge to break a wooden stick or branch.

Preferably there is a plurality of rotating branch-engaging components coupled to the flywheel means. Most preferably the or each branch-engaging component is provided on a flywheel, most preferably mounted on a flywheel.

Preferably the machine has cutting means which co-operates in use with the branch-engaging component so as to cut a branch or stick in use. Preferably the cutting means is stationery and the branch-engaging means moves past it. The cutting means preferably has a sharp edge and comprises knife means. Alternatively the cutting means may not have a sharp knife edge and may comprise shearing means, the branch or other material being sheared between the rotating branch-engaging component and the cutting means.

Preferably the rotating branch-engaging member has a projection portion that extends in the direction of the axis about which it rotates. It may have a projecting flange.

The rotating branch-engaging component may comprise an L-section elongate member.

There may be size-adjustment means provided to enable the size of chippings or mulch produced by the machine to be varied by the owner. The user may have to adjust the size-adjustment means whilst the machine is stopped, or even partially dismantled. For example, the rotating branch-engaging mean, or the cutting means, may be replaced with different versions to control the size of the chippings. The axial distance between an abutment surface provided on the flywheel, or on the branch-engaging means, and the operative edge (for example the cutting edge if it has one) of the cutting means may determine the size of wood chippings produced. This distance may be variable.

Preferably guard means is provided to guard the cutting zone. In practice we would provide a safety guard.

According to a second aspect the invention comprises a method of reducing the noise produced by a shredding machine when in use cutting or shredding a branch or the like, the method comprising using flywheel means so as to have a rotating shredding component with high kinetic energy and momentum such that the speed of rotation of the rotating shredding component necessary to ensure satisfactory cutting of suitable branches is relatively low.

Preferably the arrangement is such that the speed of rotation is less than 1000rpm, preferably less than 800 rpm, and most preferably less than 400 or 500rpm. In one embodiment the speed of rotation is 350rpm plus or minus 50rpm.

Preferably we use stationery knife means which co-operates with the rotating shredding component to cut the branch or the like.

According to a third aspect of the invention we provide a wood shredding or cutting machine having a rotating branch-engaging member and a cutting member, the branch-engaging member being adapted, when in use, to engage a branch (or other thing to be shredded) and to urge it against the cutting member so as to cut or shear it.

Preferably the cutting member is a knife and has a cutting edge, the branch-engaging member urging the branch, in use, against the cutting edge.

Preferably the cutting member is stationery and the cutting member moves past it in use. This may enable us to repair or replace the cutting member more easily than if it were a moving component.

Preferably the branch-engaging member is operatively coupled to flywheel means. Preferably it may be mounted on flywheel means. It is preferably mounted on a flywheel.

According to a fourth aspect the invention comprises a method of cutting or chopping branches, stems, twigs, or the like, comprising moving a rotating branch-engaging member past a closely spaced cutting or shearing member.

The cutting or shearing member is preferably a knife, and is preferably stationery.

The branch-engaging member preferably urges a branch to be cut against the cutting or shearing member.

In any of the aspects of the invention we may mount the machine on a frame or stand. The frame or stand may comprise part of the machine. There may be a 3-point linkage on the frame or stand adapted to connect it to a 3-point linkage of a tractor. The rotating branch-engaging component may be coupled to a rotating shaft that has connecting means adapted to connect it to the power take off of a tractor. Gearing means may be provided to enable the speed of rotation of the shaft that mounts the flywheel to be different from that of the power take off shaft of a tractor.

An embodiment of the machine will now be described by way of example only with reference to the accompanying drawings of which: Figure 1 shows a schematic view of a machine for shredding wood/garden waste; and Fidurss 2 to 7 stows sehematically details of the arrangement of the machine of Figure 1.

A chopping/shredding machine 1 is illustrated in the drawings which has a shaft 10 mounted via bearings 12 and 14 (not shown in Figure 1) on a support frame 16. The bearings are provided on cross-members 18 and 20 of the frame 16. A flywheel assembly 21 comprises a flywheel 22 mounted on the shaft 10 and three paddles 24 bolted to the flywheel 22 via bolts 26. A knife 28 is mounted on the frame 16 and is provided adjacent the flywheel 22. A feed chute 30 is also mounted on the frame and is provided adjacent the flywheel. A protective guard cover 32 is provided over the flywheel (and associated paddle and knife arrangement), but can be removed by the user for maintenance. A chipping exit guide 34 (not shown in Figure 1) is also mounted on the frame. Control means for switching the drive to the shaft 10 on and off, and/or for varying the speed is also provided, but is not shown.The control means may include a clutch.

A clutch or shear pin mechanism will usually be provided to allow for the possibility of the machine jamming.

The shaft 10 has a universal joint 36 at one end which is coupled to one end of another shaft 38, which in turn has a fitting at its other end adapted to connect to a power take-off shaft of a tractor.

The support frame 16 has a three-point linkage, referenced as 40, adapted to connect the frame to the three-point linkage of a tractor to enable the tractor to transport the machine.

The flywheel 22 has a relatively large moment of inertia (about the axis of rotation of the shaft 10) and carries the paddles 24 with it as it rotates. The paddles 24 comprise branch-engaging members which in use engage a branch, brushwood, or the like and urge the branch against the knife 28, cutting the branch.

Each paddle 24 is demountably connected to the flywheel 22 and comprises an L-section length of metal, typically steel, having a projecting portion 42 which extends in the axial direction, towards the knife 28.

This is best shown in Figure 4. The knife 28 has a cutting edge 44. In some alternative embodiments there may be no need for a cutting edge, if a shearing action will sever the branches.

Figure 2 shows the blade 28 mounted with its cutting edge 44 extending horizontally, and just below the central axis (referenced 46) of the shaft. This is also shown in Figure 5, which also shows the feed chute 30 delivering sticks etc to be chopped above the blade 28.

The feed chute 30 is also shown in Figure 7, as is the chipping exit guide 34. The diameter of the feed chute 30 controls the size of branches which can be fed into the machine. The chute will typically have a diameter of 20cm, and the machine will typically be able to cope with branches up to 8cm thick. It can, of course, also cut green wood, stems of plants, and other garden waste. Although the exit guide 34 is downwardly directed in this embodiment it could be directed to one side (or be split). It could be directed generally horizontally, or inclined from this.

The blade 28 is in this embodiment a forage harvester blade. This is strong, readily available, and because it is stationery it can be replaced easily. The guide 34 and/or guard 32 may be removable for this.

In the embodiment shown the machine runs with the flywheel rotating at 350rpm. This is practically an order of magnitude slower than the rotating blades of the prior art. We have found that this produces significantly less noise. In our embodiment we have found that we prefer to run the flywheel at less than 550rpm because of difficulty in feeding sticks in properly at high speeds. We may in other embodiments run the flywheel faster, or slower (for example it may be possible to go down to 300, 250, 200 or even lower rpm).

A surprisingly convenient feature is that the power take off shaft of most tractors rotates at about 350rpm when the tractor engine is at idle. This fits in well with the speed that we prefer to run our particular embodiment, but of course gears could be provided if it was desired to have a different speed.

It will be appreciated from a consideration of Figures 5 and 6 that, in one possible way of running the machine, as a stick is introduced into the cutting zone of the machine a length of it equal to length L shown in Figure 4 can protrude beyond the knife edge 44 (the stick abuts the front surface of the flywheel 22).

The flange 42 of the paddle 24 then, as it rotates past the open mouth of the chute 30, drags the stick (or sticks if several twigs are in the cutting zone) onto the knife 28 and the sticks are cut. Figure 4 shows that there is only a small clearance distance between the projection 42 and the cutting edge 44.

It will also be appreciated that the steel paddles 24 are heavy duty and will not be blunted, or broken, by use. This means that we do not have to repair or replace them for these reasons.

If it is desired to change the distance L, shown in Figure 4, then this could be done by moving the knife towards or away from the flywheel and changing the paddles 24 for ones with a different, complementary, length projecting flange 42.

Alternatively the flywheel might be changed for another whose front surface is at a different distance from the knife edge 44.

The speed of rotation of the flywheel may be such relative to the speed of feed of brushwood that the sticks may be cut before they contact the front face of the flywheel (and would therefore be cut into finer pieces).

Of course, we could have more or fewer than 3 paddles. We could have 4 or more, or 2, or 1. They could be provided integrally with the flywheel. We may have more than one cutting blade.

Claims

1. A wood shredding machine having a rotating branch-engaging component which in use contacts branches or other material introduced into a cutting zone of the machine so as to cause them to be cut, broken or shredded, and which has flywheel means operatively coupled to said rotating component.

2. A machine according to claim 1 in which the rotating branch-engaging component does not have a sharp, thin, edge which may be blunted or broken.

3. A machine according to claim 1 or claim 2 in which there is a plurality of rotating branch-engaging components coupled to the flywheel means.

4. A machine according to any preceding claim in which the or each branch-engaging component is provided on a flywheel.

5. A machine according to any preceding claim which has cutting means which co-operates in use with the branch-engaging component so as to cut a branch or stick in use.

6. A machine according to claim 5 in which the cutting means is stationery and the branch-engaging means moves past it.

7. A machine according to claim 5 or claim 6 in which the cutting means has a sharp edge and comprises knife means.

8. A machine according to claim 5 or claim 6 in which the cutting means comprises shearing means, the branch or other material being sheared, in use of the machine, between the rotating branch-engaging component and the cutting means.

9. A machine according to any preceding claim in which the rotating branch-engaging member has a projection portion that extends in the direction of the axis about which it rotates.

10. A machine according to claim 9 in which the branch-engaging member has a projecting flange.

11. A machine according to claim 9 or claim 10 in which the rotating branch-engaging component comprises an L-section elongate member.

12. A machine according to any preceding claim in which size-adjustment means is provided to enable the size of chippings or mulch produced by the machine to be varied by the user.

13. A machine according to any preceding claim in which guard means is provided to guard the cutting zone.

14. A machine according to any preceding claim which has a frame or stand.

15. A machine according to any preceding claim which is provided with a 3-point linkage on a frame or stand adapted to connect it to a 3-point linkage of a tractor.

16. A machine according to any preceding claim in which the rotating branch-engeging component is adapted to be coupled in use to a rotating shaft that has connecting means adapted to connect it to the power take off of a tractor.

17. A machine according to any preceding claim in which gearing means is provided to enable the speed of rotation of the shaft that mounts the flywheel to be different from that of a drive shaft that inputs power to the gearing means.

18. A wood shredding machine substantially as described herein with reference to the accompanying drawings.

19. A method of reducing the noise produced by a shredding machine when in use cutting or shredding a branch or the like, the method comprising using flywheel means so as to have a rotating shredding component with high kinetic energy and momentum such that the speed of rotation of the rotating shredding component necessary to ensure satisfactory cutting of suitable branches is relatively low.

20. A method according to claim 19 in which the arrangement is such that the speed of rotation is less than 1000rpm, or less than 800rpm or less than 500rpm.

21. A method according to claim 20 in which the speed of rotation is 350rpm plus or minus 50rpm.

22. A method according to claim 20 or claim 21 which employs stationery knife means which co-operates with the rotating shredding component to cut the branch or the like.

23. A method of reducing the noise produced by a shredding machine substantially as described herein.

24. A method of cutting or chopping branches, stems, twigs, or the like, comprising moving a rotating branch-engaging member past a closely spaced cutting or shearing member.

25. A method according to claim 24 in which the cutting or shearing member is a knife, and is stationery.