FELLING UNIT AND METHOD OF HARVESTING SMALL-DIMENSIONED WOOD

Abstract

A felling unit and a method of harvesting small-dimensioned wood in a forest. A felling unit comprises a cutting device with two disc blades and a cutting gap between them for cutting small-dimensioned trees. The cut small-dimensioned trunks are transferred from the cutting gap to a temporary storage space by means of a transfer device comprising two transfer shafts with a transfer gap between them. The disc blades and the transfer shafts are both rotated in opposite directions relative to each other, i.e. towards the cutting gap and the feeding gap.

Claims

1. A felling unit for processing small-dimensioned wood, the felling unit comprising: a frame, provided with a coupling device for attaching the frame to a boom of a movable forestry machine; at least one cutting device for the cutting of standing small-dimensioned trunks; and a temporary storage space for temporarily storing several cut small-dimensioned trunks for the time of cutting new small-dimensioned trunks; and wherein the cutting device comprises two opposite disc blades, their rims facing each other and forming between each other a cutting gap, and the disc blades are arranged to rotate in opposite directions relative to each other as driven by at least one rotating motor; the felling unit comprises the temporary storage space arranged to receive several cut small-dimensioned trunks; and the felling unit comprises a transfer device for transferring the cut small-dimensioned trunks in a feed direction from the cutting gap to the temporary storage space; wherein the transfer device comprises a first transfer shaft and second transfer shaft that are parallel to each other, the transfer shafts being rotatable in opposite directions relative to each other by means of at least one first rotating device and being located at said cutting gap at a transverse distance from each other and forming between each other a feeding gap; and wherein both of the transfer shafts comprise several transfer projections arranged to push the cut small-dimensioned trunks in the feed direction from the cutting gap towards the temporary storage space when the transfer shafts are rotating, and wherein the transfer shafts of the transfer device are rotatable in an opposite direction relative to the feed direction when small-dimensioned trunks are unloaded from the temporary storage space such that the transfer projections are arranged to push small-dimensioned trunks via the feeding gap out from the felling unit.

2. The felling unit according to claim 1, wherein the cutting device and the transfer device are arranged to cut and transfer small-dimensioned trunks as a continuous successive and uninterrupted process from the cutting gap to the temporary storage.

3. The felling unit according to claim 1, wherein each of the transfer projections is pivotably coupled by means of a hinge to the outer surface of the transfer shaft; and wherein at least part of the transfer projections are arranged to be subject to a spring force arranged to hold the transfer projections in a projected feeding position when the transfer shaft rotates in the feed direction, and which transfer projections are arranged to pivot from the feeding position towards the outer surface of the transfer shaft when an external force applied to the transfer projections exceeds said spring force.

4. The felling unit according to claim 1, wherein said disc blades are mounted on a part of first ends of the transfer shafts of the transfer device; and wherein on a part of second ends of the transfer shafts there are power transmission elements for transmitting rotation from said at least one first rotating motor to the transfer shafts.

5. The felling unit according to claim 1, wherein said disc blades comprise their own rotating shafts about which the disc blades are arranged to be rotatable by means of at least one second rotating motor; and wherein the felling unit comprises at least one first rotating device and at least one second rotating device that are separate from each other and independently operable for controlling the rotation of the disc blades and the feeding shafts independently of each other.

6. The felling unit according to claim 1, wherein the outer rims of the disc blades are toothed.

7. The felling unit according to claim 1, wherein the temporary storage space is partly delimited by a back wall of the felling unit, the back wall having a substantially U- or V-shaped cross-section and opening towards the feeding shafts that delimit the front side of the temporary storage space and towards the feeding gap between them.

8. The felling unit according to claim 1, wherein the felling unit comprises at least one control unit (CU) arranged to control the operation of the cutting device and the transfer device.

9. The felling unit according to claim 1, wherein the coupling device of the frame comprises a first turning mechanism for tilting the felling unit from a vertical position to a horizontal position.

Description

SHORT DESCRIPTION OF THE FIGURES

[0055] Some embodiments of the proposed configuration are illustrated in more detail in the accompanying figures, in which

[0056] FIG. 1 schematically illustrates one forestry machine a boom of which is provided with a felling unit for harvesting small-dimensioned wood,

[0057] FIG. 2 illustrates a simplified diagram of different steps in the harvest of small-dimensioned wood,

[0058] FIG. 3 schematically illustrates one felling unit,

[0059] FIG. 4 schematically illustrates the felling unit of FIG. 3 as a top view,

[0060] FIG. 5 schematically illustrates a detail of a transfer shaft and transfer projections in a transfer device of a felling unit,

[0061] FIG. 6 schematically presents the principle of one alternative transfer projection,

[0062] FIG. 7 schematically presents the principle of one alternative construction as a front view,

[0063] FIG. 8 schematically presents one construction in which the feeding shafts may move in a transverse direction, and

[0064] FIG. 9 schematically presents one construction in which the feeding shafts comprise several disc-type elements arranged one above the other.

[0065] For clarity purposes, some embodiments of the proposed configurations are presented in a simplified form in the figures. The same elements and features are indicated in the figures with the same reference numerals.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0066] FIG. 1 illustrates a forestry machine 1 comprising a movable chassis 2 as well as a boom 3 coupled to the chassis 2. The forestry machine 1 may be for example a track excavator as illustrated in the figure, or alternatively a forest tractor, forwarder or forest harvester. A felling unit 5 is attached to the boom 3 by means of a coupling device 4 for harvesting small-dimensioned wood 6. The felling unit 5 comprises a cutting device 7 by which the standing small-dimensioned trees 6 are cut from the base, and a transfer device 8 by which the cut small-dimensioned trunks are transferred to a temporary storage space 9 in the felling unit 5. In FIG. 1 the felling unit 5 is in the operating position arranged in the vertical direction. The forestry machine 1 comprises a control unit CU which may be arranged to also control the operation of the felling unit 5.

[0067] FIG. 2 shows a diagram illustrating the steps in the harvest of small-dimensioned wood. The felling unit 5 may be fed against the small-dimensioned trees 6 to be harvested by means of the boom 3, such that the rotating disc blades of the cutting device 7 cut the small-dimensioned trees 6 from the base. The transfer device 8 then transfers the cut small-dimensioned trunks to the temporary storage 9 in a vertical position. The feeding motion, cutting, transfer and temporary storage may be performed as a continuous process until the temporary storage space 9 is full. The temporary storage space 9 is then emptied and the harvest of a new batch of trees begins.

[0068] The felling unit 5 illustrated in FIG. 3 comprises a frame 10 provided with a coupling device 4 for attaching the felling unit to the boom of a forestry machine. The coupling device 4 may comprise a first hinge 11 shown in FIG. 1, about which the felling unit 5 may be turned from the vertical upright position shown in FIG. 1 to a horizontal unloading position by means of a hydraulic cylinder 12. Further, the coupling device 4 may comprise a second hinge 13 shown in FIG. 4, relative to which the felling unit 5 may be oriented by means of a hydraulic cylinder 14. As further shown in FIGS. 3 and 4, the frame 10 may have a shape corresponding to the letter U, whereby a temporary storage space 9 is naturally formed therein. The frame 10 comprises a back wall 15 and a bottom 16. In the upper part of the frame 10 there is a cover part 17 with an opening at the temporary storage space 9, so that the cut small-dimensioned trunks may extend up therethrough. The transfer device 8 comprises two parallel transfer shafts 18a and 18b supported to the bottom 16 and to the cover part 17. To the lower part of the transfer shafts 18a, 18b, two disc blades 19a, 19b of the cutting device 7 are mounted, whereby the transfer shafts 18 and the disc blades 19 are rotated simultaneously by means of rotating devices 20a, 20b. The rotating devices 20a, 20b may comprise rotating motors 21a, 21b as well as power transmission elements 22a, 22b such as chains or belts.

[0069] The disc blades 19a, 19b and correspondingly the transfer shafts 18a, 18b are rotated in opposite directions relative to each other towards a cutting gap 23 formed between the disc blades 19 and a transfer gap 24 formed between the transfer shafts 18. For harvesting, the small-dimensioned trees are transferred in a feed direction S towards the temporary storage 9, and for emptying in an opposite removing direction.

[0070] The outer rims of the disc blades 19 may be toothed 25, such that the disc blades 19 may feed the small-dimensioned trees to be cut towards the cutting gap 23. Thus, the disc blades form a feeding zone SV on the front side of the felling unit 5 as shown in FIG. 4.

[0071] The upper parts of the transfer shafts 18 may be provided with drum parts 18 having a larger diameter, on the outer rims of which there are several transfer projections 26. In the lower part of both of the transfer shafts 18 there may be extensions 28 having a smaller diameter, to which the disc blades 19 are mounted. The extensions 28 may also comprise transfer projections 26a for a removal operation.

[0072] As seen in FIGS. 3-5, the outer rims of the transfer shafts 18 are provided with several transfer projections 26 located at different axial and radial positions on the outer rim of the transfer shafts 18. The transfer projections 26 are tab- or finger-type elements which are each pivotably bearing-mounted by means of a hinge 29 and which are pushed to a projected transfer position by means of a spring element 30. The transfer projections 26 may pivot from their extreme projected position towards the outer surface of the transfer shaft, as FIG. 5 illustrates with an arrow 31. On the opposite side of the hinge 29 there may be a limiter part 32 which mechanically limits the movement of the transfer projection in the other direction. The movement of the transfer projection 26 towards the transfer direction is spring-loaded and in the unloading direction the coupling is mechanically unyielding.

[0073] FIG. 6 presents a very simplified view of one alternative transfer projection 26 which is pushed towards the extreme projected feeding position by means of a pressure-operated actuator, such as a hydraulic cylinder 33. A hydraulic force holds the limiter part 32 against the outer surface of the transfer cylinder 18 while enabling, as needed, a yielding pivoting movement 34 of the transfer projection 26. Alternatively, it is possible to use a compressed air cylinder.

[0074] FIG. 7 presents a very simplified view of one alternative configuration in which the disc blades 19a, 19b are arranged on their own shafts 35a, 35b and they are operated with their own rotating motors 36a, 36b. In this case, rotating speeds V1 of the cutting device 7 and rotating speeds V2 of the transfer device 8 may be unequal and separately adjustable. Further, the shafts 35a, 35b may be spaced at a greater distance from each other than the centre lines of the transfer shafts 18, whereby the disc blades 19a, 19b may have a larger diameter.

[0075] FIG. 8 presents a configuration in which the feeding shafts 18a, 18b may move in a transverse direction P, such that the width of the feeding gap 24 varies according to the small-dimensioned trees being processed. The feeding shafts 18a, 18b may be pushed by a spring force F towards each other, whereby they press the small-dimensioned trees fed to the feeding gap 24, ensuring good friction and feeding force. Detail T indicates that on the outer rim of the transfer shafts 18a, 18b there are fixed bulges or the like, operating as the transfer projections 26.

[0076] FIG. 9 presents a configuration in which the feeding shafts 18a, 18b comprise several disc-type elements 37 arranged one above the other, the outer rims of which jointly form the outer rims of the transfer shafts. The outer rims of the discs 37 may be provided with the transfer projections 26 which may be, for example, fixed bulges as shown in FIG. 8, or alternatively spring-loaded or pressure medium operated transfer projections 26 may also be used.

[0077] The figures and their description are only intended to illustrate the inventive idea. The scope of protection of the invention is, however, defined in the claims of the application