FR2741775A1 - ROTOR FOR CUTTING PLANTS - Google Patents

Abstract

The twist comprises a hollow tube (1), the wall of which is cut to present pockets (11), arranged in the internal space of the tube and opening outwards through windows (10), in which knives are arranged, said pockets (11) comprising a bottom cup (12) and side walls (13). According to the invention, the side walls (13) of said pockets (11) extend outwards from the tube (1) and the rotation shaft of the knife is mounted on these protruding parts.

Description

i

ROTOR FOR CUTTING PLANTS

  The present invention relates generally to machines for cutting plants used in the agricultural, forestry or for working in green spaces, such as the cutters,

  brushcutters, forestry or agricultural shredders.

  These machines are used for cutting small plants such as herbs, brambles or small

  bushes or for cutting branches.

  These machines use a cutting tool carried by

a hydraulic arm.

  The cutting tool is in the form of a rotor driven in rotation and carrying movable knives around axes parallel to the axis of the rotor so as to

to work like plagues.

  The rotors used for cutting the grass are often shackle rotors, that is to say rotors consisting of a hollow cylindrical piece carrying on its outer wall means for hooking the knives. These attachment means are usually composed of two yokes carrying a removable shaft to allow the knife to be placed between the two yokes. When a knife encounters an obstacle during work, it retracts by tapping on the rotor and staying against it. These rotors are of small diameter, of

around 100 mm.

  The rotors used for cutting wood are flange rotors, that is to say rotors consisting of a set of flanges or discs regularly distributed along the axis and spaced by a distance such that it allows the installation of a knife. Bars extending over the entire length of the rotor are arranged in openings of said flanges or discs so as to be parallel to the axis. These bars serve to stiffen the flanges and the shaft for rotation of the knives which are positioned around them while being disposed between two flanges. On certain rotors, the knives are mounted on an independent axis disposed between two flanges. When the knives meet an obstacle, they retract in the direction of the axis of rotation of the rotor and are positioned in the volume generated by the discs. These rotors are of diameter

important, 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 with circular section of diameter similar to the discs used previously. This tube has windows cut out from its wall. Each window is closed towards the inside of the hollow tube by a curved wall and by lateral faces perpendicular to the axis of rotation. The knives are mounted in the pockets thus formed under each window and carried by bars of the same length as the tube arranged parallel to the axis of rotation.

  of said tube and passing through said lateral faces.

  Rotors for grass are compact, light and fairly inexpensive, but cannot be used for wood because they cannot be

  provide the necessary resistance for this use.

  Rotors for wood are very heavy and expensive, but they have the advantage of being able to be rotated much more easily. Their large diameter gives them great inertia which reduces the forces to be applied. They cannot be used for cutting the grass because their configuration does not allow good evacuation of the cut grass and leads to grass jams in the spaces

between discs.

  The change of used knives is done very simply and quickly on the shackle rotors since each knife is mounted on an individual shaft carried by two yokes. This allows for a piecemeal change from

used knife at the right time.

  In the case of rotors for wood, changing used knives is much more complex. It is necessary to remove the bar serving as shaft of rotation to the knife which is an important work because of the length of this one. This shrinkage is further hampered by the deformations generated on said bars by the shocks received during work. This complexity of replacing knives pushes users to change all the knives carried by the same bar at the same time and to postpone the time of this intervention as much as possible so that all the knives are worn out even if some knives should have been changed earlier . This leads to working often

  with a rotor having lost its efficiency.

  The disassembly of knives mounted independently between the flanges, is often also

  difficult due to the deformation of said flanges.

  Whatever the type of assembly, with a very long bar or with an independent axis, there frequently occur blockages in rotation of the knife on its axis

  which generates destructive vibrations.

  These important differences between the rotors for cutting grass and the rotors for cutting wood oblige users, farmers, bridge and road services ... to have two machines to be able to make all the cuts, which is a major problem. their budget. It therefore appears desirable to have a rotor which can be used interchangeably for grass and for wood. To this end, the present invention provides a rotor for cutting plants of the type comprising a hollow tube, the wall of which is cut to present pockets, arranged in the internal space of the tube and opening towards the outside through windows, in which are arranged knives, said pockets having a bottom cup and side walls, characterized in that the side walls of said pockets extend towards the outside of the tube and in that the rotation shaft of the

  knife is mounted on these protruding parts.

  The rotor according to the invention is also remarkable in that: - the knife rotation shaft is mounted on the protruding parts very close to the hollow tube, - the protruding parts of the side walls are of rounded shape, - for each pocket, the cup and the side walls are joined together and to the tube by welding, - the pockets are constituted by a sub-assembly consisting of a bottom and two flanges, said sub-assembly is welded around the circumference of a window, - said sub-assembly is removably mounted in the hollow tube, - said sub-assembly is snap-fitted into the tube, - a bayonet mount is used for the

  mounting said sub-assembly in the tube.

  The invention will be better understood thanks to the

  description which will follow given by way of example not

  limiting with reference to the accompanying drawings in which: - Figure 1 is a partial front view of a rotor according to the invention, - Figure 2 is a sectional view along line II-II of Figure 1, - the Figure 3 is a partial view of the development of a hollow tube used for the manufacture of a rotor according to the invention, - Figure 4 shows an alternative embodiment

  pockets arranged in the hollow tube of the rotor.

  As shown in Figure 1, the rotor according to the invention is formed of a hollow tube 1 of circular section, the wall of said tube being cut to

show windows 10.

  As shown in FIG. 3, the windows 10 are of rectangular projection. This FIG. 3 shows the projection of the plane P of section used

for the view of figure 2.

  The windows are, in the embodiment shown in the drawing, regularly distributed along two spirals starting at diametrically opposite points of the tube 1. The windows arranged on one of the spirals are positioned in staggered rows relative to the windows arranged on the another spiral. In a manner known per se, these windows can, as a variant, be positioned

  along lines parallel to the axis of rotation of the rotor.

  Pockets 11 opening outwards through the

  windows 10 are created in the internal space of the tube 1.

  In the embodiment shown in the drawing, these pockets have a cup 12 and walls

side 13.

  For each pocket 11, the cup 12 and the side walls 13 can be joined together and at

  tube 1 by welding as in figure 2.

  According to the invention, the side walls 13 of each pocket 11 extend towards the outside of the tube 1 and the mounting of the knife rotation shaft is carried out on

these protruding parts.

  By such an assembly, the knife is articulated on a circle C ′ of diameter greater than the diameter of the tube 1. Its stroke represented in FIG. 2 by the circles in thin lines C takes place largely outside of said tube 1 which ensures good evacuation of cut plants and allows the use of the rotor according to

  the invention for cutting grass.

  As can be seen in the drawing, the knife rotation shaft is mounted on the protruding parts very close to the hollow tube so as to limit the deformations of these protruding parts. Preferably, only the passage necessary for the fitting of the clamping bolts of the knife rotation shafts is left between said

  rotation shafts and hollow tube.

  Preferably, and as shown in the drawing, the protruding parts of the side walls are rounded in order to present a smaller grip on obstacles. The presence of the pockets 11 allows the knives to retract into the volume of the tube without hitting the hollow tube when the rotor encounters significant obstacles such as stumps which makes it possible to use it for cutting wood and improves working conditions

  knives when cutting the grass.

  The invention thus provides a rotor suitable both for the

  cutting grass than cutting wood.

  The replacement of the rotor knives according to the invention is done individually, each knife being mounted on a rotation shaft carried by bearings

  fixed to the protruding parts of the side walls 13.

  The assembly according to the invention allows a rapid change in the use of the rotor by changing only the knives, which avoids handling of heavy parts

usually necessary.

  The rotor according to the invention will for example be produced using a hollow tube with 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 much greater than that of rotors usually used for cutting grass, its rotation does not require

therefore only reasonable efforts.

  This limitation of the forces necessary for driving the rotor makes it possible to reduce the need for

  power and therefore achieve energy savings.

  The ventilation phenomena produced during the rotation of the rotor according to the invention are lower, which makes the work quieter and improves.

absorption of vegetation.

  According to the embodiment schematically shown in Figure 4, the pockets are constituted by a sub-assembly 3 consisting of a bottom 32 similar to the cups 12 and two flanges 33 similar to the walls

side 13.

  This sub-assembly is either welded to the periphery of the window 10 which receives it so as to create a one-piece assembly of the same type as that shown in FIG. 2,

  is removably mounted in the hollow tube.

  Such a sub-assembly can be manufactured by mechanical welding, forging or foundry so as to be very solid

and substantially undeformable.

  The removable mounting of the sub-assembly can be carried out in any known manner in mechanics, snap-fastening by the installation of elastic tabs coming to bear against the internal face of the tube, bayonet mounting by cutting openings on the edge of the windows 10 for the passage of fingers intended to be positioned under

the wall of the hollow tube.

1 C

Claims (10)

  1. - Rotor for cutting plants of the type comprising a hollow tube (1), the wall of which is cut to present pockets (11), arranged in the internal space of the tube and opening towards the outside through windows (10 ), in which knives are arranged, said pockets (11) comprising a bottom cup (12) and side walls (13), characterized in that the side walls (13) of said pockets (11) extend towards the outside of the tube (1) and in that the rotation shaft of the   knife is mounted on these protruding parts.   2. - Rotor according to claim 1, characterized in that the knife rotation shaft is mounted on the   protruding parts very close to the hollow tube.   3. - Rotor according to claim 1 or according to claim 2, characterized in that the protruding parts of the side walls (11) are of rounded shape.   4. Rotor according to any one of the claims   1 to 3, characterized in that for each pocket (11), the cup (12) and the side walls (13) are   secured to each other and to the tube (1) by welding.   5. - Rotor according to any one of   Claims 1 to 3, characterized in that the pockets are   constituted by a sub-assembly (3) composed of a bottom (32) and two flanges (33).   6. - Rotor according to claim 5, characterized in that said subassembly (3) is welded on the periphery a window (10).   7. - Rotor according to claim 5, characterized in that said subassembly (3) is mounted so removable in the hollow tube (1).   8. - Rotor according to claim 7, characterized in that said sub-assembly (3) is mounted by snap-fastening in the tube (1).   9. - Rotor according to claim 7, characterized in that a bayonet mounting is used for mounting   of said subassembly (3) in the tube (1).   10.- Rotor according to any one of   claims 1 to 9, characterized in that it is suitable   both when cutting grass and when cutting wood.