GB2307630A

GB2307630A - Rotor for cutting plants

Info

Publication number: GB2307630A
Application number: GB9624955A
Authority: GB
Inventors: Jacques Bachmann
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-12-01
Filing date: 1996-11-29
Publication date: 1997-06-04
Anticipated expiration: 2016-11-29
Also published as: FR2741775B1; GB2307630B; GB9624955D0; FR2741775A1

Abstract

The rotor comprises a hollow tube (1), the wall of which is cut to form pockets (11), arranged within the interior space of the tube and opening towards the outside via windows (10), in which are arranged blades, said pockets (11) comprising a base cup (12) and lateral walls (13). The lateral walls (13) of said pockets (11) extend towards the outside of the tube (1) and the rotation shaft of the blade is mounted on these projecting parts.

Description

ROTOR FOR CUTTING PLANTS The present invention generally relates to machines for cutting plants which are used in the fields of agriculture, forestry or for working open spaces, examples of such machines are hedge cutting machines, scrub-clearing machines, or flail trimmers for forestry or agricultural purposes.

These machines are used for cutting small plants such as grasses, brambles or small bushes or for cutting branches.

These machines use a cutting implement borne by a hydraulic arm.

The cutting implement is in the form of a rotor driven in rotation and bearing blades which are mobile about axes parallel to the axis of the rotor so as to operate like flails.

The rotors used for cutting grass are often shackle rotors, that is to say, rotors formed of a hollow cylindrical part bearing on its outer wall means for attaching the blades. These attachment means are usually composed of two devises or yokes bearing a dismountable shaft to permit the positioning of the blade between the two devises. When a blade encounters an obstacle during operation, it retracts by hitting the rotor and remaining against it. These rotors are of small diameter, of the order of 100 mm.

As for the rotors used for cutting wood, they are plate rotors, that is to say, rotors formed of a set of plates or discs distributed regularly along the axis and spaced apart by a distance such that it permits the positioning of a blade. Bars extending over the entire length of the rotor are arranged in openings in the plates or discs so as to be parallel to the axis.

These bars serve to stiffen the plates and rotation shaft to the blades which are positioned around them, being arranged between two plates. On some rotors, the blades are mounted on an independent axis arranged between two plates. When the blades encounter an obstacle, they retract towards the axis of rotation of the rotor and become positioned in the volume formed by the discs. These rotors are of large diameter, of the order of 400 mm.

Another embodiment of these rotors for cutting wood is proposed in FR 2 277 624. In this embodiment, the rotor is composed of a hollow tube of circular section, of a diameter similar to the discs used previously. This tube has windows cut into its wall.

Each window is closed towards the interior of the hollow tube by a curved wall and by lateral faces perpendicular to the axis of rotation. The blades are mounted in the pockets thus formed beneath each window and borne by bars of the same length as the tube and arranged parallel to the axis of rotation of said tube and passing through said lateral faces.

The rotors for grass take up little space, are not very heavy and are relatively inexpensive, but cannot be used for wood because it is not possible to impart thereto the strength necessary for this use.

As for the rotors for wood, they are very heavy and expensive, but they have the advantage of being able to be driven in rotation far more easily. The large diameter thereof imparts great inertia thereto, which makes it possible to reduce the forces to be applied. They cannot be used for cutting grass because their configuration does not permit ready evacuation of the cut grass and results in clogging by grass in the spaces between the discs.

Changing the worn blades can be done very simply and quickly on the shackle rotors since each blade is mounted on an individual shaft borne by two devises.

This permits change independently piece by piece of the worn blade at a suitable moment.

In the case of rotors for wood, changing of the worn blades is far more complex. It is necessary to remove the bar acting as a rotation shaft for the blade, which is a major operation owing to the length thereof. This removal is further hampered by the deformations caused to said bars by impacts to which they are subjected during operation. This complexity of replacement of the blades encourages the users to change all the blades borne by the same bar at the same time and to put off this intervention for as long as possible so that all the blades are worn, even if some blades ought to have been replaced earlier. This results in often working with a rotor which has lost its effectiveness.

The dismounting of the blades mounted independently between the plates is often also difficult owing to the deformation of said plates.

Whatever the type of mounting, with a bar of great length or with an independent axis, frequently blockages occur in the rotation of the blade on its axis, which results in destructive vibrations.

These major differences between the rotors for cutting grass and the rotors for cutting wood force the users, farmers, highway departments, etc., to have two machines available in order to be able to effect all the cutting operations, which puts a considerable strain on their budgets.

It would therefore appear to be desirable to have a rotor which can be used equally for grass and for wood.

To this end, the present invention proposes a rotor for cutting plants of the type comprising a hollow tube, the wall of which is cut to form pockets, arranged within the interior space of the tube and opening towards the outside via windows, in which are arranged blades, said pockets comprising a base cup and lateral walls, characterised in that the lateral walls of said pockets extend towards the outside of the tube and in that the rotation shaft of the blade is mounted on these projecting parts.

The rotor according to the invention is furthermore distinguished in that: - the rotation shaft of the blade is mounted on the projecting parts very close to the hollow tube, - the projecting parts of the lateral walls are rounded in shape, - for each pocket, the cup and the lateral walls are made integral with each other and with the tube by welding, - the pockets are formed by a sub-assembly composed of a base and two plates, - said sub-assembly is welded to the periphery of a window, - said sub-assembly is mounted removably in the hollow tube, - said sub-assembly is mounted in the tube by latching, - a bayonet mounting is used for mounting said subassembly in the tube.

The invention will be better understood with reference to the following description, given by way of non-limiting example with reference to the appended drawings, in which: - Figure 1 is a partial front view of a rotor according to the invention, - Figure 2 is a section along the line II-II in Figure 1, - Figure 3 is a partial view of the evolute of a hollow tube used for the production of a rotor according to the invention, - Figure 4 shows a variant of embodiment of the pockets arranged in the hollow tube of the rotor.

As can be seen in Figure 1, the rotor according to the invention is formed by a hollow tube 1 of circular section, the wall of said tube being cut out to form windows 10.

As shown in Figure 3, the windows 10 are of rectangular projection. The projection of the cutting plane P used for the view of Figure 2 has been shown in this Figure 3.

The windows, in the example of embodiment illustrated in the drawing, are regularly distributed in two spirals starting at diametrically opposed points on the tube 1. The windows arranged on one of the spirals are positioned staggered relative to the windows arranged on the other spiral. In known manner, in a variant these windows may be positioned in lines parallel to the axis of rotation of the rotor.

Pockets 11 which open towards the outside via the windows 10 are formed in the inner space of the tube 1.

In the example of embodiment illustrated in the drawing, these pockets comprise a cup 12 and lateral walls 13.

For each pocket 11, the cup 12 and the lateral walls 13 may be connected together and to the tube 1 by welding as in Figure 2.

According to the invention, the lateral walls 13 of each pocket 11 extend towards the outside of the tube 1 and the mounting of the rotation shaft of the blade is effected on these projecting parts.

By such mounting, the blade is articulated on a circle C' of a diameter greater than the diameter of the tube 1. The path thereof illustrated in Figure 2 by the circles C shown in short dashes is located for the major part on the outside of said tube 1, which ensures good evacuation of the cut plants and permits the use of the rotor according to the invention for cutting grass.

As can be seen in the drawing, the rotation shaft of the blade is mounted on the projecting parts very close to the hollow tube so as to restrict the deformation of these projecting parts. Preferably, only the passage necessary for positioning the fastening bolts of the rotation shafts of the blades is left between said rotation shafts and the hollow tube.

Preferably, and as illustrated in the drawing, the projecting parts of the lateral walls are rounded in shape so as to present less access to obstacles.

The presence of the pockets 11 enables the blades to retract into the volume of the tube without hitting the hollow tube when the rotor encounters major obstacles such as stumps, which makes it possible to use it for cutting wood and improves the operating conditions for the blades when cutting grass.

The invention thus provides a rotor suitable both for cutting grass and for cutting wood.

The replacement of the blades of the rotor according to the invention is effected individually, each blade being mounted on a rotation shaft borne by bearings fixed to the projecting parts of the lateral walls 13.

The mounting according to the invention permits a quick change of use of the rotor by only changing the blades, which avoids the manipulation of heavy parts which is usually necessary.

The rotor according to the invention will for example be produced using a hollow tube of a diameter of the order of 200 mm.

Such a rotor has an inertia similar to that of the rotors usually used for cutting wood and therefore considerably superior to that of the rotors usually used for cutting grass, and the rotation thereof therefore only requires reasonable forces.

This limitation of the forces necessary for driving the rotor makes it possible to reduce the power demand and hence to make energy savings.

The ventilation phenomena produced during the rotation of the rotor according to the invention are less, which makes operation quieter and improves the absorption of the vegetation.

According to the embodiment diagrammatically illustrated in Figure 4, the pockets are formed by a sub-assembly 3 composed of a base 32 similar to the cups 12 and two plates 33 similar to the lateral walls 13.

This sub-assembly is either welded to the periphery of the window 10 which receives it so as to create an integral unit of the same type as that shown in Figure 2, or mounted removably in the hollow tube.

Such a sub-assembly may be produced by machine welding, forging or foundry so as to be very solid and substantially non-deformable.

The removable mounting of the sub-assembly can be effected in any manner known in mechanics, latching by positioning elastic lugs which come to bear against the inner face of the tube, or bayonet mounting by cutting out openings on the edge of the windows 10 for fingers intended to be positioned beneath the wall of the hollow tube to pass through.

Claims

1. A rotor for cutting plants, of the type comprising a hollow tube (1), the wall of which is cut to form pockets (11), arranged within the interior space of the tube and opening towards the outside via windows (10), in which are arranged blades, said pockets (11) comprising a base cup (12) and lateral walls (13), characterised in that the lateral walls (13) of said pockets (11) extend towards the outside of the tube (1) and in that the rotation shaft of the blade is mounted on these projecting parts.

2. A rotor according to Claim 1, characterised in that the rotation shaft of the blade is mounted on the projecting parts very close to the hollow tube.

3 A rotor according to Claim 1 or according to Claim 2, characterised in that the projecting parts of the lateral walls (11) are rounded in shape.

4. A rotor according to any one of Claims 1 to 3, characterised in that for each pocket (11), the cup (12) and the lateral walls (13) are made integral with each other and with the tube (1) by welding.

5. A rotor according to any one of Claims 1 to 3, characterised in that the pockets are formed by a subassembly (3) composed of a base (32) and two plates (33).

6. A rotor according to Claim 5, characterised in that said sub-assembly (3) is welded to the periphery of a window (10).

7. A rotor according to Claim 5, characterised in that said sub-assembly (3) is mounted removably in the hollow tube (1).

8. A rotor according to Claim 7, characterised in that said sub-assembly (3) is mounted in the tube (1) by latching.

9. A rotor according to Claim 7, characterised in that a bayonet mounting is used for mounting said subassembly (3) in the tube (1).

10. A rotor according to any one of Claims 1 to 9, characterised in that it is suitable both for cutting grass and for cutting wood.

11. A rotor for cutting plants substantially as herein described with reference to Figures 1 to 3, or those Figures modified by Figure 4, of the accompanying drawings.