Method for processing wood in wood processing device of forest work machine and control system for controlling operation of wood processing device

Abstract

A method for processing a tree (17) in a wood processing device (20) of a forest work machine (1), which comprises movable feeding means (22) pressable against the tree trunk for feeding the tree (17) in the wood processing device (20) and movable delimbing means (24a, 24b) pressable against the tree trunk for removing branches from the tree trunk. The tree (17) is fed in the wood processing device (20) by said feeding means (22) and, during the feed of the tree (17), branches are removed from the tree trunk by said delimbing means (24a, 24b) at the same time as the tree (17) is supported in the wood processing device (20) by said feeding means (22) and / or delimbing means (24a, 24b). In the method, a substantially vertical support force (FS) required for supporting the tree (17) in the wood processing device (20) is determined and at least one of following for producing said substantially vertical support force (FS) is adjusted: pressing force (PF22) of the feeding means (22) against the tree trunk or pressing force (PF24) of the delimbing means (24a, 24b) against the tree trunk. Furthermore, a control system (30) for controlling the operation of a wood processing device (20) of a forest work machine (1).

Description

[0001] Method for processing wood in wood processing device of forest work machine and control system for controlling operation of wood processing device

[0002] Background of the invention

[0003] The invention relates to wood harvesting and particularly to a method for tree processing in a wood processing device of a forest work machine and a control system for controlling the operation of the wood processing device.

[0004] When harvesting wood by a forest work machine, the wood is processed i.e. worked in the wood processing device of the forest work machine. Said wood processing typically comprises felling of a tree, removing branches from the felled tree i.e. delimbing, and cross-cutting the trunk of the felled tree into parts of preferred length. For delimbing the tree trunk, the felled tree is fed by means of feeding means pressable against the tree trunk in the wood processing device and, at the same time, delimbing means used for removing the branches are pressed against the tree trunk in the wood processing device. After this, such a section of the tree trunk of which branches have been removed or which had no branches originally is cross-cut into a part of preferred length.

[0005] During delimbing, the tree being processed in the wood processing device is held up by said feeding means and said delimbing means at the same time as the tree being processed is fed by said feeding means forward in the wood processing device. If the pressing force of said delimbing means against the tree trunk is too low, the delimbing result is weak, that is, branch stubs or branch lumps remain on the surface of the tree trunk. Additionally, the support of the tree against the bottom of the wood processing device is weakened, whereby the tree may start to dangle in the wood processing device. Then, the height of the tree in the wood processing device changes and the measurement accuracy of the diameter of the tree is weakened. Furthermore, the delimbing means might cut inside the tree trunk or the tree may even totally fall off the wood processing device. Because the surface of the tree trunk slides along the frame of the wood processing device, a too high pressing force of said delimbing means against the tree trunk increases resistance for the feeding of the tree in the wood processing device, that is, the friction resisting the travel of the tree in the wood processing device increases. This again increases the power required for wood processing and the energy consumption. If the pressing force of said feeding means against the tree trunk is too low, the feeding of the tree in the wood processing device is weakened, which slows down wood processing and thus decreases productivity. If the pressing force of said feeding means against the tree trunk is in turn too high, unnecessarily much power is used for holding up, supporting and feeding the tree trunk, which unnecessarily increases energy consumption of wood processing. Additionally, said feeding means, particularly those implemented as feeding rolls, might damage the surface of the tree.

[0006] According to a solution in use, the pressing force of the feeding means of the wood processing device against the tree trunk and the pressing force of the delimbing means against the tree trunk are controlled based on a measured diameter of the tree being processed. The measurement of the tree diameter is based on determining the aperture of said feeding means and / or delimbing means. In the solution in question, as the feeding of the tree proceeds, the pressing force is decreased when the diameter of the tree decreases. In order for the support of the tree to the wood processing device to be sufficient during the feeding of the tree, that is, also in the end stage of the feeding of the tree, the pressing force of the feeding means and delimbing means used for supporting the tree is often too high, which may cause above-mentioned disadvantages during the processing of the tree.

[0007] Brief description of the invention

[0008] The object of the invention is to provide a new type of a method for processing a tree in a wood processing device of a forest work machine and a new type of a control system for controlling the operation of the wood processing device of the forest work machine.

[0009] The solution according to the invention is characterised by what is disclosed in the independent claims.

[0010] The invention is based on the fact that, for processing the tree in the wood processing device of the forest work machine, a substantially vertical support force required for supporting the tree is determined and at least one of the following is adjusted for producing said substantially vertical support force when processing the tree in the wood processing device: a pressing force of feeding means against the tree trunk or a pressing force of delimbing means against the tree trunk.

[0011] An advantage of the solution is that, when determining the substantially vertical support force required for supporting the tree in the wood processing device, the pressing force of the feeding means against the tree trunk and / or the pressing force of the delimbing means against the tree trunk may be adjusted more optimally for producing the support force required in reality for supporting the tree. Then, it is possible to avoid the production of very high pressing forces typically used to be on the safe side for the sufficient support of the tree and thus decrease the energy consumption of wood processing. Even though the main purpose of the solution is to avoid the production of an unnecessarily high pressing force and thus typically decrease the used pressing forces, due to the solution, it is also possible to increase the used pressing forces, if required, if the operating situation of the wood processing device so requires. Due to the solution, the pressing force of the feeding means of the feeding device and / or the delimbing means of the delimbing device of the wood processing device may be adjusted such that the pressing of the delimbing means against the tree trunk is sufficient for both supporting the tree in the harvester head and for delimbing the tree trunk substantially without branch stubs or branch lumps remaining on the surface of the tree trunk but still such that said pressing forces are not too high to cause a force resisting the feeding of the tree in the harvester head due to too strong support of the tree.

[0012] Some embodiments of the invention are presented in the dependent claims.

[0013] Brief description of the drawings

[0014] The invention will now be described in greater detail by means of preferred embodiments and with reference to the attached drawings, in which:

[0015] Figure 1 is a schematic side view of a forest work machine,

[0016] Figure 2 is a schematic diagonal top view of a wood processing device of a forest work machine,

[0017] Figure 3 is schematic side view of the wood processing device of the forest work machine of Figure 2 and a tree being supported by it,

[0018] Figure 4 is a schematic view of a control system of a wood processing device of a forest machine for controlling the operation of the wood processing device,

[0019] Figure 5 is a schematic view of a method for controlling the operation of the wood processing device of a forest work machine, and

[0020] Figures 6a and 6b are schematic views of some ways for supporting a tree in a wood processing device for adjusting a substantially vertical support force.

[0021] For reasons of clarity, some embodiments of the invention are illustrated in the figures in a simplified form. Similar parts are indicated in the figures by the same reference numbers. Detailed description of the invention

[0022] Figure 1 is a schematic side view of a harvester 1 which is a forest work machine wherein the above-described solution can be applied. The harvester 1 comprises a chassis 2, which constitutes at least part of the frame structure of the harvester 1 and into connection with which are arranged moving means 3, by means of which, the harvester 1 may move in relation to its work surface or work environment. Said moving means 3 are wheels in Figure 1, but generally said moving means can comprise at least one of the following: wheels arranged on an axle, wheels arranged on a bogie, a track system or some other means known as such to provide the movement of the forest work machine and to possibly change the direction of the movement of the forest work machine in relation to its work surface or work environment.

[0023] The harvester 1 further comprises a power source 4. The power source 4 can comprise e.g. a combustion engine, one or more electric motors and sets of batteries, and / or a generator or different combinations of these for generating the required power for providing the movement of the harvester, for increasing its movement speed and for operating the devices arranged in the harvester.

[0024] The harvester 1 additionally comprises a cab 5. The cab 5 may be arranged foldably and / or rotatably in relation to the chassis 2. The cab 5 comprises required control means 6, by means of which, the operator of the harvester may control the drive of the harvester and the devices arranged to it. Said control means 6 are shown very schematically in Figure 1 and they may comprise e.g. one or more manually controllable control means, such as e.g. a control lever, and / or one or more foot-controllable control means, such as e.g. a pedal. Said control means 6 can also comprise a pre-designed harvester work plan in the form of a runnable programme which is runnable by e.g. one or more harvester control units 7 very schematically shown in Figure 1 for controlling the drive of the harvester and the devices arranged in it. Said control unit 7 can be e.g. a computer or some other device or means comprising a microprocessor or some other microcontroller that is obvious to those skilled in the art.

[0025] The harvester 1 further comprises a boom 8. The boom 8 can be supported e.g. on the chassis 2 or a base 9 connected to the chassis or some other part of the harvester frame or a part connected to it. The boom 8 may be arranged foldably and / or rotatably in relation to the chassis 2. The outmost end of the boom 8 includes a harvester head 20 forming the wood processing device of the harvester 1. The outmost end of the boom 8 and the harvester head 20 arranged to it constitute a tip of the boom 8.

[0026] The boom 8 of the harvester 1 of Figure 1 includes a lifting boom 10. The lifting boom 10 is moved by a lifting cylinder 11. Furthermore, a luffing boom 12 is pivoted to the lifting boom 10. The luffing boom 12 is moved by a folding cylinder 13. The luffing boom 12 further includes a telescopic extension 14 movable by its own actuator, at the outmost end of which, the harvester head 20 is arranged via a hanger 16. The structure of the boom 8 may also differ from the one shown in Figure 1 for example such that the boom 8 does not include said telescopic extension 14.

[0027] The harvester 1 of Figure 1 constitutes a mobile forest work machine equipped with a wood processing device, which is intended for performing the felling of trees, delimbing the felled tree and cross-cutting the trunk of the felled tree into parts of preferred length. Alternatively, the mobile forest work machine equipped with a wood processing device can also be a combination of a forwarder and a harvester, whereby the forest work machine in question also comprises a load space for taking a load, typically parts of the trunk of the tree 17 cross-cut to size, to be transported by the forest work machine. Furthermore, the mobile work forest machine equipped with a wood processing device may also be some other mobile forest work machine suitable for felling trees and processing felled trees, such as e.g. a digger with a wood processing device fixed to its boom.

[0028] The forest work machines of Figure 1 are typically forest work machines operating based on the active control of the operator of the forest work machine. However, it is also possible to apply the here presented solution in both semi-autonomously operating forest work machines, whereby the forest work machine can operate without the active control of the operator at least for some time, and in a substantially totally autonomously operating forest work machine, whereby the operator does not actively contribute to the control of the forest work machine operations without a special reason. The control means used for the control of the forest work machine can also be located separate from the forest work machine, whereby the control of the forest work machine is implemented by remote control. If the control of the forest work machine is totally implementable by remote control or automatically, the forest work machine does not necessarily include the cab 5.

[0029] Figure 2 schematically shows a diagonal top view of a harvester head 20. When a felled tree 17 is being worked i.e. processed in the harvester head to remove branches, the felled tree is fed in the harvester head typically into one direction and simultaneously branches are removed from the trunk of the tree. After branches have been removed for a preferred length of the tree trunk, the tree trunk is cross-cut by removing the part in question of the delimbed section of the tree trunk from the not yet delimbed section of the tree trunk. This is repeated until the tree top is reached. The harvester head 20 of Figure 2 is applicable for performing the felling of the tree, removing branches and, if necessary, also bark from the felled tree, and cross-cutting the trunk of the felled tree into parts of preferred length. However, the here presented solution is also applicable in such a wood processing device which is only applicable for removing branches and possibly also bark from an already felled tree and the cross-cutting of the tree trunk in question, which wood processing devices are also sometimes called processing heads of a forest work machine to separate them from harvester heads also suitable for tree felling.

[0030] The harvester head 20 of Figure 2 comprises a frame structure 20’ into connection with which a hanger 16 is arranged. Furthermore, into connection with the frame structure 20’, means intended for the felling of the tree and the processing of the felled tree fitted to the harvester head 20 are arranged. The means intended for tree felling and processing the felled tree typically comprise a feeding device 21, a delimbing device 23 and a cross-cutting device 25. The feeding device 21 is used for supporting the tree during felling and for feeding the tree in the harvester head 20 when processing the felled tree 17 in the harvester head 20. The delimbing device 23 is used for supporting the tree during felling and for removing branches of the felled tree 17 i.e. for delimbing the tree 17 being fed with the feeding device 21 in the harvester head 20. The cross-cutting device 25 is used for cross-cutting the tree being felled and for cross-cutting the tree 17 being processed in the harvester head 20 into parts of preferred length.

[0031] The tree 17 being processed by the harvester head 20 is fed by the feeding device 21 forward from a front part 20a of the harvester head 20 into the direction of a rear part 20b of the harvester head 20. If required, the tree 17 can also be fed backward from the direction of the rear part 20b of the harvester head 20 into the direction of the front part 20a of the harvester head 20. During said feed of the tree 17, branches are removed from the trunk of the tree 17 by the delimbing device 23. In the harvester head 20 of Figure 2, the delimbing device 23 is arranged for the part of front delimbing knives 24a to the front part 20a of the harvester head 20, via which, the tree 17 being processed is fed forward in the harvester head 20, and for the part of rear delimbing knives 24b between the feeding device 21 and cross-cutting device 25. The part of the trunk of the tree 17, from which branches have been removed or in which there was no branches originally, is crosscut into parts of preferred length by the cross-cutting device 25 which is arranged in the rear part 20b of the harvester head 20. The cross-cutting device 25 is thus in the typical travel direction of the tree 17 through or via the harvester head 20 the last device that, for the part of the harvester head 20, directs processing measures to the tree 17 being processed in the harvester head 20.

[0032] The feeding device 21 of the harvester head 20 comprises feeding means which are pressed against the trunk of the tree 17 for both supporting the tree to be felled during the felling and for feeding the felled tree 17 being processed by the harvester head 20 by using said feeding means in the harvester head 20. In the harvester head 20 of Figure 2, said feeding means comprise movable feeding rolls 22 which are pressed, by using one or more actuators related to them, against the surface of the trunk of the tree 17 and rotated for feeding the tree 17 being processed in the harvester head 20. Said feeding rolls 22 in the harvester head 20 of Figure 2 are rolls equipped with outward directed toothing. Furthermore, the harvester head 20 may include feeding rolls fixedly supported on the frame 20’ of the harvester head 20. Instead of the feeding rolls 22, the feeding means may be e.g. continuous feeding belts or chains of the chain track type.

[0033] The delimbing device 23 of the harvester head 20 comprises movable delimbing means which are pressed against the trunk of the tree 17 for both supporting the tree to be felled during the felling and for delimbing the felled tree 17 being processed by the harvester head 20 when the felled tree 17 is being fed by the feeding device 21 in the harvester head 20. In the harvester head 20 of Figure 2, said delimbing means comprise both front delimbing knives 24a located in the direction of the front part 20a of the harvester head 20 in relation to the feeding rolls 22, that is, the delimbing knives 24b located in front of the feeding rolls 22 seen in the typical feeding direction of the tree 17, and rear delimbing knives 24b located in the direction of the rear part 20b of the harvester head 20 in relation to the feeding rolls 22, that is, the rear delimbing knives 24b located behind the feeding rolls 22 seen in the typical feeding direction of the tree 17. The delimbing knives 24a, 24b are pressed using one or more actuators related to them against the surface of the trunk of the tree 17 for removing the branches from the tree 17 being processed in the harvester head 20. Alternatively, the harvester head 20 can sometimes only comprise the front delimbing knives 24a. In addition to said movable delimbing knives 24a, 24b, the harvester head can also include fixed delimbing knives, either as separate knives fastened or shaped on the frame structure of the harvester head, or delimbing knives which can be somewhat elastic from the effect of a force applied to them either for the part of their fastening or their own structure. An example of this kind of knives is a top delimbing knife 24c schematically shown in Figure 2.

[0034] The cross-cutting device 25 of the harvester head 20 comprises one or more cross-cutting means, by using which, the tree to be felled is both cross-cut at a preferred point and cross-cut into parts of preferred length when the felled tree 17 is processed in the harvester head 20. In the harvester head 20 of Figure 2, the cross-cut means is constituted by a chain-saw-type cross-cut saw 26 which is used, by using one or more actuators related to it, both to the cross-cutting of the tree being felled and to cross-cutting the felled tree 17 into parts of preferable length. The cross-cut saw can also be implemented as a cross-cut saw of the circular saw or rotary saw type. Instead of the cross-cut saw 26, the cross-cutting means can also be e.g. one or two moving cut off blades. Figure 3 is a schematic side of the harvester head 20 of Figure 2 and the tree 17 being supported by it.

[0035] Typically, the harvester head 20 and the feeding device 21, the delimbing device 23 and the cross-cutting device 25 in it are hydraulically operated devices, comprising actuators operating by means of substantially incompressible fluid pressure medium for controlling the operation of the feeding means of the feeding device 21, the delimbing means of the delimbing device 23 and the crosscutting means of the cross-cutting device 25 by affecting the pressure and / or volume flow and / or flow direction of pressure medium being fed to said actuators in a way known as such by those skilled in the art. As the electrical operation of work machines increases, at least part of said devices or all said devices can also be implemented as electrically or electro-hydraulically operated, whereby their operation can be controlled e.g. by controlling the electric power fed to them or their actuators.

[0036] Figure 4 schematically shows a control system 30 for controlling the operation of a wood processing device of a forest work machine. The example of a control system 30 shown in Figure 4 is particularly configured to control the operation of a harvester head 20 of the kind shown in Figures 2 and 3 but it is naturally configurable to control also other kinds of harvester heads or processing heads.

[0037] The control system 30 of Figure 4 comprises a control unit 31 which is arranged or configured, in accordance with this description, to particularly control the operation of the feeding device 21 and / or the delimbing device 23 but it may also control e.g. the operation of the cross-cutting device 25. The control unit 31 may be implemented as a part of a control unit 7 of the harvester 1 or it may be a control unit physically separate from the control unit 7 of the harvester 1 but functionally configured to work together with the control unit 7 of the harvester 1.

[0038] The control system 30 is configured to control the feeding means of the feeding device 21 of the harvester head 20 for supporting and feeding the tree 17 being processed in the harvester head 20 by means of said feeding means of the feeding device 21 pressable against the trunk of the tree 17 and / or to control the delimbing means of the delimbing device 23 of the harvester head 20 against the trunk of the tree 17 being fed in the harvester head 20 for removing branches from the trunk of the tree 17 and to support the trunk of the tree 17 against the bottom of the harvester head 20. Said delimbing means can also be used for removing the bark in the trunk of the tree 17. In the harvester head 20 in accordance with the example of Figures 2 and 3, said feeding means are then feeding rolls 22 and said delimbing means are delimbing knives 24a, 24b.

[0039] According to the solution, the control system 30 is configured to determine a substantially vertical support force FS directed substantially perpendicularly upward against the bottom of the harvester head 20, required for supporting the tree 17 in the harvester head 20 and further to adjust, when processing the tree 17 in the harvester head 20, at least one of the following for producing said substantially vertical support force FS: a pressing force PF22 of the feeding means of the feeding device 21 of the harvester head 20 against the trunk of the tree 17 or a pressing force PF24 of the delimbing means of the delimbing device 23 against the trunk of the tree 17. If the harvester head 20 comprises both the front delimbing knives 24a and the rear delimbing knives 24b, the front delimbing knives 24a and the rear delimbing knives 24b can be pressed against the trunk of the tree 17 with a force different from the other.

[0040] The control system 30 is thus configured to implement a method wherein, for processing a tree 17 in a wood processing device of a forest work machine, the tree 17 is fed in the wood processing device by feeding means of a feeding device 21, branches are removed from the trunk of the tree 17 during the feeding of the tree 17 by delimbing means of a delimbing device 23, a substantially vertical support force FS directed upward, required for supporting the tree 17 in the wood processing device is determined, and at least one of the following is adjusted for producing said substantially vertical support force FS when processing the tree 17 in the wood processing device: a pressing force PF24 of the feeding means of the feeding device 21 against the trunk of the tree 17 or a pressing force PF24 of the delimbing means of the delimbing device 23 against the trunk of the tree 17. Figure 5 schematically shows a method for controlling the operation of a wood processing device of a forest work machine according to the solution in question.

[0041] When determining a substantially vertical support force FS required for supporting the tree 17 in the harvester head 20 and adjusting, based on the determined support force FS, pressing force PF22 of the feeding means of the feeding device 21 against the trunk of the tree 17 and / or pressing force PF24 of the delimbing means of the delimbing device 23 against the trunk of the tree 17, it is possible to adjust the operation of the feeding device 21 and / or the delimbing device 23 such that the pressing of the delimbing means against the trunk of the tree 17 is sufficient for both supporting the tree in the harvester head 20 and for removing branches from the trunk of the tree 17 substantially without branch stubs or branch lumps remaining on the surface of the trunk of the tree 17 such that said pressing forces PF22, PF24 are not too high to cause a force resisting the feed of the tree 17 in the harvester head 20 caused by the too strong support of the tree in the harvester head 20. At the same time, the pressing force PF24 of the delimbing means against the trunk of the tree 17 required for producing the preferable effect can be taken into consideration when adjusting the pressing force PF22 of the feeding means against the trunk of the tree 17, whereby the pressing force PF22 of the feeding means against the trunk of the tree 17 can be adjusted sufficient for feeding the tree effectively in the harvester head 20 but not too high for forming unnecessarily strong support for the tree being processed in addition to the one the delimbing means already product for supporting the tree 17 against the bottom or rolls therein or other slide surface of the harvester head 20.

[0042] Due to the solution, it is thus possible to reach a good end result for removing branches from the trunk of the tree 17 without a significant number of branch stubs or branch lumps remaining on the surface of the trunk and without using an unnecessarily high force for the holding up and support of the trunk of the tree 17, whereby the energy consumption used for wood processing does not increase unnecessarily. Furthermore, when the tree 17 being processed in the harvester head 20 is sufficiently supported on the bottom of the harvester head 20, the measuring accuracy of the measurement of the diameter, i.e., thickness, of the tree 17 is also improved. Then, the accuracy of calculation of tree volume based on the measurement of the diameter of the tree 17 or the accuracy of determination of volume estimate of the tree is also improved, which facilitates the control of the cross-cutting of the tree 17 such that the tree 17 may be more efficiently utilised for uses that produce greater economic added value.

[0043] The control unit 31 of the control system 30 of Figure 4 is configured to control via a control connection CO-21 the operation of the feeding device 21, such as e.g. the pressing force PF22 of the feeding means against the trunk of the tree 17, and via a control connection CO-23 the operation of the delimbing device 23, such as e.g. the pressing force PF24 of the delimbing means against the trunk of the tree 17. Furthermore, the control unit 21 can be configured to control the operation of the cross-cutting device 25 by means of a control connection CO-25. Data describing the operation of the feeding device 21, the delimbing device 23 and the cross-cutting device 25 or measurements performed in each of them may be transferred to the control unit 31 by means of corresponding data transfer connections Ml-21, Ml-23 and Ml-25. Other data describing the operation of the harvester head 20 or measurements performed in the harvester head may be transferred to the control unit 31 via a data transfer connection Ml-20.

[0044] The control unit 31 may be e.g. a computer or some other device or means comprising a microprocessor or some other micro controller, obvious to the those skilled in the art, which is configured to perform via a programme stored in the control unit 31, based on measurement data received by the control unit 31 and / or data further determined based on them, control measures affecting the operation of the feeding device 21, the operation of the delimbing device 23 and / or the operation of the cross-cutting device 25. In practice, said control measures performed by the control unit 31 provide, in a way known as such by those skilled in the art, a required change in the operation of the feeding device 21, the delimbing device 23 and / or the cross-cutting device 25 as a response to a change e.g. in the pressure and / or volume flow and / or flow direction of pressure medium and / or electric power being fed to one or more actuators related to them.

[0045] In addition to the control unit 31, the control system 30 may include, in accordance with what will later be described in relation to different embodiments, various sensors or other means, by means of which, a substantially vertical support force FS required for supporting the tree 17 in the harvester head 20 may be determined. The control system 30 may also include a database 32 for storing the support force FS used in the processing of the tree 17 being processed and data used for its determination or other data. Furthermore, data related to the operation of the harvester head 20 or devices attached to it may be stored in the database 32. In addition, it is possible to store data corresponding to the above data describing the control measures applied to the feeding device 21, the delimbing device 23 and possibly also the cross-cutting device 25 to the database 32. Said data describing the control measures applied to the feeding device 21 and the delimbing device 23 may be e.g. a pressing force PF24 of the delimbing means against the trunk of the tree 17 used for processing the tree 17 and / or a pressing force PF22 of the feeding means againstthe trunk of the tree 17 used for processing the tree 17. The database 32 may comprise tree-species-specific data sets and may thus comprise e.g. stored tree-species-specific history data related on processed trees on control measures applied to the feeding device 21, the delimbing device 23 and possibly also the cross-cutting device 25, which data may be further utilised in later wood harvesting sites of corresponding tree species to control the operation of the feeding device 21, the delimbing device 23 and possibly also the cross-cutting device 25. Furthermore, the database 32 may comprise tree-species-specific data on different tree species, such as e.g. specific weights and taper curve details of different tree species. The taper curve of the tree 17 may be e.g. a mathematical model for the diameter of the tree formed as a function of the tree length or height, which is statistically adapted to a large set of previously collected measurement data, which comprises at least a detail on the diameter of the trees of the same tree species processed previously, or an equation which represents a curve adapted to said previously collected measurement data.

[0046] According to an embodiment, when the tree is supported by the wood processing device, a substantially vertical load applied to at least one of the following is determined: the wood processing device, the feeding means or the delimbing means, and a substantially vertical support force required for supporting the tree in the wood processing device is determined based on at least one determined substantially vertical load.

[0047] With reference to e.g. the examples of Figures 2 and 3, in this embodiment, a load applied to the harvester head 20 and / or the feeding rolls 22 of the feeding device 21 and / or the delimbing knives 24a, 24b of the delimbing device 23 in the harvester head 20 is thus determined, and a substantially vertical support force FS directed upwards, required for supporting the tree in the harvester head 20 is determined based on said one or more loads.

[0048] According to an embodiment, a detail describing the mass of the tree or its part is determined, based on the detail describing the mass of the tree or its part is determined a substantially vertical load applied to at least one of the following: the wood processing device, the feeding means or the delimbing means, and a substantially vertical support force required for supporting the tree in the wood processing device is determined based on at least one determined substantially vertical load.

[0049] The detail describing a mass M17 of the tree 17 or its part is one alternative to express a substantially vertical load LD directed downward caused by the tree 17 or its part applied to the wood processing device and / or the feeding means and / or the delimbing means when the tree 17 or its part is supported by the wood processing device. The size of the tree affects the mass M17 of the tree 17 or its part. In addition to the size of the tree 17 or its part, the specific weight of the tree species affects the mass M17 of the tree 17 or its part. The number and size of branches of the tree 17 somewhat affects the mass M17 of the tree 17 or its part but the weight of the branches of the tree 17 or its part is not typically a significant factor compared with the weight of the trunk of the tree 17.

[0050] A detail describing the mass M17 of the tree 17 or its part may be determined e.g. by measuring the mass M17 of the tree 17 or its part by a weighing device arranged to the wood processing device whereby, with reference to e.g. Figure 4, the harvester head 20 may comprise a weighing device 20M arranged into connection with the hanger 16 for determining the detail describing the mass M17 of the tree 17 or its part. Said detail describing the mass M17 of the tree 17 or its part may then e.g. be the weight of the tree 17 or its part measured directly by weighing as kilograms.

[0051] Another alternative to express a substantially vertical load LD caused by the tree 17 or its part to the wood processing device and / or the feeding means and / or the delimbing means, when the tree 17 or its part is supported by the wood processing device, is to determine a substantially vertical force effect directed downward caused by the tree 17 or its part on the wood processing device and / or the feeding means and / or the delimbing means. Said substantially vertical force effect directed downward may be determined by e.g. at least one force or load sensor arranged into connection with the wood processing device and / or the feeding means and / or the delimbing means, which is schematically shown in Figure 4 designated by reference 20FD in connection with the harvester head 20, reference 21FD in connection with the feeding device 21 and reference 23FD in connection with the delimbing device 23. In the harvester head 20, said at least one force or load sensor 20FD may be arranged into connection with e.g. the hanger 16, and the force or load sensors 21FD, 23FD used in connection with the feeding device 21 and the delimbing device 23 may be located into connection with e.g. the hanging of the feeding and delimbing means.

[0052] The at least one force or load sensor 20FD arranged to the harvester head 20 produces a measurement signal FD20 describing the load LD applied to the harvester head 20. Equivalently, the force or load sensors 21FD, 23FD arranged into connection with the feeding device 21 and the delimbing device 23 produce measurement signals FD21, FD23 describing the load applied to the feeding means of the feeding device 21 and the delimbing means of the delimbing device 23, whereby said measurement signals FD21, FD23 should, if all sensors in question are available, together produce a result substantially corresponding the measurement signal FD20 for the part of the load LD applying to the harvester head 20 from the tree 17 or its part. Said substantially vertical load LD directed downward is thus dependent at least partially on the mass M17 of the tree 17 or its part and is thus at least in some extent a detail describing the mass M17 of the tree 17 or its part. Equivalently, the detail describing the mass M17 of the tree 17 or its part may directly or indirectly describe the load LD applied by the tree 17 or its part to the harvester head 20 or the load applied to the feeding means of the feeding device 21 and / or the delimbing means of the delimbing device 23, whereby the substantially vertical support force FS required for supporting the tree in the wood processing device may be determined directly based on the detail describing the mass M17 of the tree 17 or its part without determining the above described one or more measurement signals FD20, FD21, FD23 describing the load.

[0053] The above mentioned detail describing the mass M17 of the tree 17 or its part or the substantially vertical load directed downward caused by the tree 17 or its part to the wood processing device and / or the feeding means and / or the delimbing means forms a minimum target value for the substantially vertical support force FS required for supporting the tree in the wood processing device, which minimum target value the substantially vertical support force FS must reach in order for the tree 17 or its part not fall from the support of the wood processing device. In practice, said support force FS must still be somewhat higher in order for the tree 17 to be supported sufficiently strongly in the wood processing device for, inter alia, the efficient delimbing of the tree 17.

[0054] The position and state of motion of the wood processing device may also affect the support force FS required for supporting the tree 17 in the wood processing device in various use situations of the wood processing device, either increasing or decreasing it. Therefore, according to an embodiment, a position and a state of motion of the wood processing device are determined and, in addition to a detail describing the mass of the tree or its part, based on the position and state of motion of the wood processing device, a substantially vertical load applied to at least one of the following: the wood processing device, the feeding means or the delimbing means.

[0055] During the processing of the tree 17, a substantially horizontal position of the wood processing device, such as schematically shown for example in Figure 3, may indicate that the tree 17 being processed is in totality supported by the wood processing device. During the processing of the tree 17, a position of the wood processing device different from the substantially horizontal position or vertical position, that is, an oblique position, such as schematically shown for example in Figure 1, may for its part indicate that the tree 17 being processed is not in totality supported by the wood processing device but is somewhat supported by the working surface of the forest work machine. Then, the detail describing the mass M17 of the tree 17 or its part or the detail describing the substantially vertical load LD directed downward caused by the tree 17 or its part does not describe the actual mass of the tree 17 or its part or the substantially vertical load LD caused by the actual mass of the tree 17 or its part but only a part of it. In this case, as the processing of the tree 17 proceeds, the observed mass of the tree 17 or its part or the substantially vertical load LD directed downward caused by the tree 17 or its part can even increase when the remaining part of the tree 17 being processed transfers totally to be supported by the wood processing device despite parts of the felled tree already have been removed. This possibility must also be considered when adjusting the pressing force of the feeding means and / or the delimbing means against the trunk of the tree 17. The position of the wood processing device may be determined by at least one position sensor arranged into connection with the wood processing device which, with reference to the example of Figure 4, is designated by reference 20PO and produces a measurement signal P020 describing the position of the harvester head 20.

[0056] As mentioned above, in the embodiment in question, the state of motion of the wood processing device is also determined in addition to the position of the wood processing device. The state of motion of the wood processing device determines if the wood processing device is in motion or substantially stationary when the tree 17 is processed in the wood processing device. The motion of the wood processing device typically increases the need to raise the support force FS used for supporting the tree 17 particularly during the decelerations and / or accelerations of the motions of the wood processing device, whereby variable forces caused by said decelerations and / or accelerations of the motions of the wood processing device also apply to the tree 17, which may be considered when determining the support force FS needed for supporting the tree 17.

[0057] The motion of the wood processing device typically occurs as a result of changes in the position of the wood processing device or as a result of a motion of the boom 8 of the forest work machine. The motion of the wood processing device occurring as a result of changes in the position of the wood processing device may be determined e.g. based on the measurement signal P020 produced by atleast one position sensor 20PO arranged to the wood processing device. The motion of the wood processing device occurring as a result of the motion of the boom 8 may be determined e.g. by means of a sensor set of the boom 8, schematically shown in Figure 4 and designated by reference 8MS, that describes the states of motion of the boom 8, which sensor set produces at least one measurement signal MS8 describing the state of motion of the boom 8, which may be transferred to the control unit 31 via a data transfer connection Ml-8. Said sensor set may comprise e.g. sensors measuring details that describe the speed, acceleration or position of the parts of the boom 8.

[0058] According to an embodiment, when processing a tree in the wood processing device, for determining a detail describing the mass of the tree or its part, measuring a diameter and length of the trunk of the tree, determining based on the measured diameter and the length of the part of the trunk of the tree related to the measurement of the diameter at least one of the following details: a volume detail of the part of the trunk of the tree the diameter of which was measured, or a volume estimate of the part of the trunk of the tree where the diameter of the trunk of the tree was not measured, and determining a detail describing the mass of the tree or its part based on the specific weight of the tree species of the tree and at least one of the following details: a volume detail of the part of the tree the diameter of which was measured, or a volume estimate of the part of the tree where the diameter of the trunk of the tree has not been measured.

[0059] In this embodiment shown as a part of Figure 4, the control system 30 comprises means for measuring a diameter D17 and a length L17 of the trunk of the tree 17 and the control system 30 is configured, when processing a tree 17 in the wood processing device, for determining a detail describing the mass M17 of the tree 17 or its part, to measure the diameter D17 and length L17 of the trunk of the tree 17, to determine based on the measured diameter D17 and the length of the part of the trunk of the tree related to the measurement of the diameter at least one of the following details: a volume detail VI of the part of the trunk of the tree 17 the diameter of which was measured, or a volume estimate VE of the part of the trunk of the tree 17 where the diameter of the trunk of the tree was not measured, and determining a detail describing the mass M17 of the tree 17 or its part based on the specific weight of the tree species of the tree and at least one of the following details: a volume detail VI of the part of the tree 17 the diameter D17 of which was measured, or a volume estimate VE of the part of the tree 17 where the diameter of the trunk of the tree 17 has not been measured. The specific weight TSW of the tree species of the tree 17 maybe retrieved e.g. from a database 32 where it was stored e.g. before starting the felling.

[0060] The diameter D17 ofthe trunk of the tree 17, that is, the thickness of the trunk of the tree 17, may be determined according to an embodiment by measuring the diameter D17 of the trunk of the tree 17 when feeding the tree 17 in the wood processing device. With reference to examples of Figures 1-4, where the wood processing device is a harvester head 20, the diameter D17 of the trunk of the tree 17 may be measured by a position transducer set 23P arranged in the delimbing device 23, which is configured to determine the position of the delimbing knives 24a, 24b of the delimbing device 23 when the delimbing knives 24a, 24b are pressed against the trunk of the tree 17. According to another embodiment, the diameter D17 of the trunk of the tree 17 may be measured by a position transducer set 21P arranged in the feeding device 21, which is configured to determine the position of the feeding rolls 22 of the feeding device 21 when the feeding rolls 22 are pressed against the trunk of the tree 17. According to a further embodiment, the diameter D17 of the trunk of the tree 17 may be determined by measuring the time used for cross-cutting a part of the trunk of the tree 17, whereby the cross-cutting device 25 comprises a position transducer set 25P to indicate the position of the cross-cut saw 26 at the start and the end of the cross-cutting motion, whereby the time that passes when the cross-cut saw 26 turns from its position in the start of the crosscutting motion to its position at the end of the cross-cutting motion describes the diameter D17 of the trunk of the tree 17. According to an additional embodiment, for measuring the diameter D17 of the trunk of the tree 17, the control system 30 may comprise imaging means 40, such as a camera 41, a video camera 42 and / or a laser scanning device 43, which is / are configured for non-contacting imaging ofthe trunk of the tree 17 when feeding the tree 17 in the wood processing device and the control unit 31 is configured to determine the diameter D17 of the trunk of the tree 17 from the information produced by said imaging. Said imaging means 40, which are schematically shown in Figure 4, may be arranged e.g. to the wood processing device or the boom 8 of the forest work machine.

[0061] The length L17 of the trunk of the tree 17 may be measured e.g. by a sensor set 20L arranged to the wood processing device, which is configured, when feeding the tree 17 in the wood processing device, to measure the length of the trunk or a part of the trunk of the tree fed in the feeding stage in question, thus describing also the length of the part of the trunk of the tree related to the diameter measurement performed in the same feeding stage. Said sensor measuring the length of the trunk of the tree may be e.g. a blade wheel arranged to the bottom of the harvester head 20. Alternatively, said length of the trunk of the tree may be measured e.g. via the image information produced by the above-mentioned camera 41 or video camera 42.

[0062] Based on the measured diameter D17 of the trunk of the tree 17 and the length L17 of the trunk of the tree 17 related to the measurement of the diameter D17, it is possible in the control unit 31 of the control system 30 to determine at least one of the following details: a volume detail VI of the part of the tree 17 the diameter D17 of which was measured, or a volume estimate VE of the part of the trunk of the tree 17 where the diameter D17 of the trunk of the tree 17 has not been measured. Based on the volume detail VI of the part of the tree 17 the diameter D17 was measured and / or the volume estimate VE of the part of the trunk of the tree 17 where the diameter of the trunk of the tree 17 has not been measured, it is further possible to determine a detail describing the mass M17 of the tree 17 or its part, based on which, either directly or based on a load LD caused by the tree 17 or its part, and possibly together with details describing the position and state of motion of the wood processing device, it is possible to determine a support force FS required for supporting the tree 17 in the wood processing device and further, when needed, to adjust a pressing force PF22 of the feeding means against the trunk of the tree 17 and / or a pressing force PF24 of the delimbing means against the trunk of the tree.

[0063] The above-mentioned volume detail VI of the tree 17 thus produces a detail of the load caused by the part already processed in the wood processing device but not detached from the tree 17 being processed and the volume estimate VE of the tree 17 produces a detail of the load caused by the part being at least partially supported by the wood processing device and possibly coming to be supported by it to the wood processing device, which details may be used in real-time for adjusting the pressing force PF22 of the feeding means against the trunk of the tree 17 and / or the pressing force PF24 of the delimbing means against the trunk of the tree 17 for producing the support force FS required to support the tree in the wood processing device.

[0064] According to an embodiment, determining a mass estimate for the part of the tree trunk where the diameter of the tree trunk has not been measured based on at least one of the following details: said volume detail or said volume estimate, determining based on the mass estimate a substantially vertical load applied to the wood processing device by the part of the tree corresponding the mass estimate, determining based on the substantially vertical load applied to the wood processing device by the part of the tree corresponding the mass estimate a substantially vertical support force required for supporting the part of the tree corresponding to the mass estimate, cross-cutting the part of the tree not related to said mass estimate, and adjusting at least one of the following for producing the substantially vertical support force corresponding the mass estimate: pressing force of the feeding means against the tree trunk or pressing force of the delimbing means against the tree trunk.

[0065] In this embodiment shown as a part of Figure 4, the control system 30 is configured, via the control unit 31 configured correspondingly, to determine a mass estimate ME17 for the part of the trunk of the tree 17 where the diameter of the trunk of the tree 17 has not been measured, based on the specific weight TSW of the tree species of the tree and at least one of the following details: said volume detail VI or said volume estimate VE. Furthermore, the control system 30 is configured to determine based on the mass estimate ME17 a substantially vertical load LDMEI7 directed at the wood processing device by the part of the tree 17 corresponding to the mass estimate ME17, to determine based on said substantially vertical load LDMEI7 a substantially vertical support force FSMEI? required for supporting the part of the tree 17 corresponding the mass estimate ME17 in the wood processing device, to control the cross-cutting device 25 to cut a part of the tree 17 not related to said mass estimate ME17, and to adjust the pressing force PF22 of the feeding means against the trunk of the tree 17 and / or the pressing force PF24 of the delimbing means against the trunk of the tree 17 for producing said substantially vertical support force FSMEI?.

[0066] Hence, in this embodiment, a mass estimate ME 17 is determined for the part of the trunk of the tree 17 the diameter of which part of the trunk of the tree 17 has not been measured and, based on it, further a support force FSMEI? required to support said part of the trunk of the tree 17. After that, when said part of the trunk of the tree 17 has been detached from the tree 17, based on the support force FSMEI7 required for supporting the part of the trunk of the tree 17 corresponding said mass estimate ME17, the pressing force PF24 of the feeding means against the trunk of the tree 17 and / or the pressing force PF24 of the delimbing means against the trunk of the tree 17 may be stepwise dropped to such a level that is sufficient to support the part of the tree not yet processed in the wood processing device sturdily on the wood processing device. Then, the processing of said tree 17 in the wood processing device may be continued by clearly lower pressing forces which may be still adjusted in a smaller quantity when further processing the tree based on the determinable diameter D17 of the trunk of the tree 17.

[0067] According to an embodiment, when determining a detail describing the mass M17 of the tree 17 or its part to be processed in the wood processing device, the tree or its part is imagined before the felling of said tree, and a mass estimate M17 describing the mass of the tree 17 or its part is determined based on the specific weight TSW of the tree species of the tree 17 and the imaging of the tree 17 or its part, such as e.g. based on a diameter D17 of the trunk or a part of the trunk of the tree 17 determined based on imaging. The tree 17 or its part may be imaged e.g. by photographing the tree 17 or its part, by video photographing the tree 17 or its part and / or by laser scanning the tree 17 or its part. For imaging the tree 17, it is possible to use e.g. the above mentioned imaging means 40, such as a camera 41, a video camera 42 and / or a laser scanning device 43.

[0068] According to an embodiment, the control system 30 comprises at least one of the following for determining a detail describing the mass M17 of the tree 17 or its part being processed: at least one means for determining the position of the lifting boom 10 of the boom 8 of the forest work machine, at least one sensor for determining the pressure of the lift cylinder 11 of the lifting boom 10 of the boom 8 of the forest work machine, or at least one sensor for determining the pressure prevailing in the operating ports of the directional control valves of the wood processing device. In this case, the control system 30 may be configured to determine a detail describing the mass M17 of the tree 17 or its part being processed in the wood processing device based on at least one of the following details: a position of the lifting boom 10 of the boom 8, a pressure of the lift cylinder 11 of the lifting boom 10 of the boom 8 of the forest work machine or a pressure prevailing in the operating ports of the directional control valves of the wood processing device. Generally, this embodiment may utilise the kinematics, mass and inertia, state of motion and the force / moment caused by actuators of the boom together. In this embodiment, it is thus possible to utilise data determinable even solely based on the operation of the boom 8 for determining the substantially vertical support force FS required for supporting the tree 17 in the wood processing device. If one or more devices used for the operation of the boom and / or wood processing device is electric or electro-hydraulic, it is also possible to use data on the electric power used for operating said device for determining the substantially vertical support force FS required for supporting the tree 17 in the wood processing device.

[0069] According to an embodiment, as a response to the cutting of a part of the tree off the tree being processed in the wood processing device, the substantially vertical support force required for supporting the tree in the wood processing device is dropped stepwise by adjusting at least one of the following: pressing force of the feeding means against the tree trunk or pressing force of the delimbing means against the tree trunk. Furthermore, according to this embodiment, the tree is fed in the wood processing device by said feeding means and, as the feed of the tree proceeds in the wood processing device, said at least substantially vertical support force is kept constant or it is increased by adjusting at least one of the following: pressing force of the feeding means against the tree trunk or pressing force of the delimbing means against the tree trunk.

[0070] Figures 6a and 6b schematically show methods according to this embodiment for adjusting the substantially vertical support force FS produced in the wood processing device for supporting the tree 17. The top parts of Figures 6a and 6b schematically show the trunk of the tree 17 being processed in the wood processing device and the decrease of its diameter from the butt end of the tree 17 on the left towards the top end of the tree 17 on the right. In the length direction, the tree 17 is divided into parts which correspond to the parts of the tree 17 designated by references 1-1, 1-2 and 1-3. Furthermore, Figures 6a and 6b show, below the tree 17, the support force FS used for supporting the tree 17 in the wood processing device as the processing of the tree 17 proceeds in the wood processing device.

[0071] In the examples of Figures 6a and 6b, the diameter of the tree 17 in its butt end is designated by reference D-l. When starting the processing of the tree 17, the support force FS required for supporting the tree 17 in the wood processing device is set to a value FSD-I by adjusting the pressing force of the feeding means and / or the delimbing means against the trunk of the tree 17. Said value FSD-I of the support force may be determined based on the diameter D-l of the butt end of the tree 17, utilising e.g. the specific weight of the tree species and the taper curve specific to the tree species in question, based on which, it is possible to determine e.g. a mass estimate for the tree 17 to be processed and further to determine the support force FSD-I required for supporting the tree 17 in the wood processing device. Said mass estimate for the tree 17 to be processed and further the support force FSD-I required for supporting the tree 17 in the wood processing device may be determined e.g. in ways described above.

[0072] When the processing of the tree 17 in the wood processing device is started, the tree 17 is fed in the wood processing device until the feed of the tree 17 is paused when the part of the trunk of the tree 17 corresponding the length part 1-1 of the tree 17 is detachable from the tree 17. After the part of the trunk of the tree 17 corresponding the length part 1-1 of the tree 17 has been detached from the tree 17 but before the feed of the tree 17 in the wood processing device is continued, the support force FSD-2 required for supporting the part of the tree 17 not yet processed is set based on the initial diameter D-2 of the tree’s length part 1-2. Alternatively, for determining said support force FSD-2, it is possible to utilise e.g. the volume detail of the length part 1-1 of the trunk of the tree 17 or the mass estimate of the part of the tree 17 not yet processed as described above. When the processing of the tree 17 in the wood processing device is continued, the tree 17 is fed further in the wood processing device until the feed of the tree 17 is paused when the part of the trunk of the tree 17 corresponding the length part 1-2 of the tree 17 is detachable from the tree 17. After the part of the trunk of the tree 17 corresponding the length part 1-2 of the tree 17 has been detached from the tree 17, the support force FSD-3 required for supporting the part of the tree 17 not yet processed in the wood processing device is set based on the diameter D-3 of the tree’s length part 1-3 or the volume detail of the length part 1-2 of the trunk of the tree 17 or the mass estimate related to the part of the tree 17 not yet processed. The processing of the tree 17 is continued in an equivalent way until the tree 17 has been processed for the parts processable in the wood processing device.

[0073] In the embodiments of Figures 6a and 6b, a support force required for supporting the tree 17 in the wood processing device is determined. When it is possible to detach from the tree 17 the part that has already been processed in the wood processing device, the support force required for supporting the part of the tree 17 still remaining unprocessed may be dropped stepwise to correspond the calculatory support force required for supporting the remaining tree by adjusting the pressing force of the feeding means against the tree trunk and / or the pressing force of the delimbing means against the tree trunk. The embodiments of Figures 6a and 6b differ from each other for the part of the adjustment of the support force FS during the feeding of the tree 17. In the embodiment of Figure 6a, as the feed of the tree 17 proceeds, the support force is increased substantially linearly until the processed length part of the tree 17 has been cut off from the part of the tree 17 not yet processed in the wood processing device, after which, the support force is decreased stepwise to substantially correspond to the support force required for supporting the part of the tree 17 not yet processed in the wood processing device. Said increase in the support force ensures the sufficient support of the tree 17 in each use situation of the wood processing device, that is, even in such a use situation where the part of the tree 17 not yet processed will come in its totality, even unexpected, to the support of the wood processing device or where the volume detail or mass estimate of the tree is not very accurately determinable. In the embodiment of Figure 6b, as the feed of the tree 17 proceeds, the support force is kept substantially constant until the processed length part of the tree 17 has been cut off from the part of the tree 17 not yet processed in the wood processing device, after which, the support force is decreased stepwise to substantially correspond to the support force required for supporting the part of the tree 17 not yet processed in the wood processing device. By keeping the support force substantially constant, it is possible to decrease the force required for supporting the tree 17 during its processing but, for determining the support force required for supporting the tree, the required volume detail or mass estimate or some other detail must be more accurately determinable than in the embodiment of Figure 6a.

[0074] By means of the presented solution and its various embodiments, the pressing force of the feeding means of the feeding device against the tree trunk and / or the pressing force of the delimbing means of the delimbing device against the tree trunk may be adjusted as required by each work or use situation of the wood processing device, which increases the efficiency of wood processing by avoiding the use of too high pressing forces compared with the actual requirement which has been previously common. At the same time, the too high mechanical stresses applied to the wood processing device are decreased, which decreases the maintenance or replacement need of the wood processing device or its components and increases the efficiency of work by decreasing the unproductive periods of the forest work machine for the part of the wood processing device.

[0075] Those skilled in the art will find it obvious that, as technology advances, the basic idea of the invention may be implemented in many different ways. The invention and its embodiments are thus not restricted to the examples described above but may vary within the scope of the claims.

Claims

Claims1. A method for processing a tree (17) in a wood processing device (20) of a forest work machine (1), which comprises movable feeding means (22) pressable against the tree trunk for feeding the tree (17) in the wood processing device (20) and movable delimbing means (24) pressable against the tree trunk for removing branches from the tree trunk, and in which method feeding the tree (17) in the wood processing device (20) by said feeding means (22), removing branches from the trunk of the tree by said delimbing means (24a, 24b) during the feeding of the tree (17) and supporting the tree (17) in the wood processing device (20) by said feeding means (22) and / or delimbing means (24a, 24b), characterized by determining a detail describing a mass (M17) ofthe tree (17) or its part, determining, based on the detail describing the mass (M17) of the tree (17) or its part, a substantially vertical load (LD) applying to at least one of the following: the wood processing device (20), the feeding means (22) or the delimbing means (24a, 24b), determining a substantially vertical support force (FS) required for supporting the tree (17) in the wood processing device (20) based on at least one determined substantially vertical load (LD) and adjusting at least one of following when processing the tree (17) in wood processing device (20) for producing said substantially vertical support force (FS): pressing force (PF22) of the feeding means (22) against the tree trunk or pressing force (PF24) of the delimbing means (24a, 24b) against the tree trunk.

2. A method according to claim 1, characterized by determining a position (PO20) and state of motion of the wood processing device (20) and determining, in addition to a detail describing the mass (M17) of the tree (17) or its part, based on the position (PO20) and state of motion of the wood processing device (20), a substantially vertical load (LD) applying to at least one of the following: the wood processing device (20), the feeding means (22) or the delimbing means (24a, 24b).

3. A method according to claim 1 or 2, characterized by, when processing the tree (17) in the wood processing device (20), for determining a detail describing the mass (M17) of the tree (17) or its part,measuring a diameter (17) and a length (L17) of the trunk of the tree, determining, based on the measured diameter (D17) and the length (L 17 ) of the tree trunk related to the measurement of the diameter (D17), at least one of the following details: a volume detail (VI) of the part of the tree trunk the diameter (D17) of which was measured, or a volume estimate (VE) of the part of the tree trunk where the diameter (D17) of the tree trunk has not been measured, and determining a detail describing the mass (M17) of the tree (17) or its part based on a specific weight (TSW) of the tree species of the tree (17) and at least one of the following details: a volume detail (VI) of the part of the tree trunk the diameter (D17) of which was measured, or a volume estimate (VE) of the part of the tree trunk where the diameter (D17) of the tree trunk has not been measured.

4. A method according to claim 3, characterised by the wood processing device (20) comprising a cross-cutting device (25) and by determining a mass estimate (ME17) for the part of the tree trunk where the diameter (D17) of the tree trunk has not been measured based on at least one of the following details: said volume detail (VI) or said volume estimate [VE), determining based on the mass estimate (ME 17) a substantially vertical load (LD) applied to the wood processing device (20) by the part of the tree corresponding the mass estimate (ME17), determining based on the substantially vertical load (LD) applied to the wood processing device (20) by the part of the tree corresponding to the mass estimate (ME17) a substantially vertical support force (FS) required for supporting the part of the tree corresponding to the mass estimate (ME 17) in the wood processing device (20), cutting of the tree (17) the part of the tree unrelated to said mass estimate (ME17), and adjusting at least one of following for producing the substantially vertical support force (FS) corresponding to the mass estimate (ME17): pressing force (PF22) of the feeding means (22) against the tree trunk or pressing force (PF24) of the delimbing means (24a, 24b) against the tree trunk.

5. A method according to claim 1 or 2, characterized by, when determining a detail describing the mass (M17) of the tree (17) or its part to be processed in the wood processing device (20), imaging the tree (17) or its part before felling said tree (17) and determining a mass estimate (ME17) describing the mass (M17) of the tree (17) or its part based on the specific weight of the tree species (TSW) of the tree (17) and the imaging of the tree (17) or its part.

6. A method according to claim 5, characterized by imaging the tree (17) or its part in a way that is at least one of the following: by photographing the tree (17) or its part, by video photographing the tree (17) or its part or by laser scanning the tree (17) or its part.

7. A method according to any one of the previous claims, characterized by the wood processing device (20) comprises a cross-cut device (25) and, as a response to the cutting off the part of the tree trunk from the tree (17) being processed in the wood processing device (20), dropping stepwise the substantially vertical support force (FS) required for supporting the tree (17) in the wood processing device (20) by adjusting at least one of the following: pressing force (PF22) of the feeding means (22) against the tree trunk or pressing force (PF24) of the delimbing means (24a, 24b) against the tree trunk, feeding the tree (17) in the wood processing device (20) by said feeding means (22) and as the feed of the tree (17) in the wood processing device (20) proceeds, keeping said substantially vertical support force (FS) substantially constant or raising it by adjusting at least one of the following: pressing force (PF22) of the feeding means (22) against the tree trunk or pressing force of the delimbing means (24a, 24b) against the tree trunk.

8. A control system (30) for controlling the operation of a wood processing device (20) of a forest work machine (1), which wood processing device (20) comprises movable feeding means (22) pressable against the tree trunk for feeding the tree (17) in the wood processing device (20) and movable delimbing means (24a, 24b) pressable against the tree trunk for removing branches from the tree trunk, and which control system (30) is configured to control the feed of the tree (17) in the wood processing device (20) by said feeding means (22),the removing of branches from the trunk of the tree by said delimbing means (24a, 24b) during the feeding of the tree (17) and the supporting of the tree (17) in the wood processing device (20) by said feeding means (22) and / or delimbing means (24a, 24b), characterized in that the control system (30) comprises means for determining a detail describing a mass (M17) of the tree (17) or its part, and that the control system (30) is further configured to determine a detail describing a mass (M17) of the tree (17) or its part, to determine, based on the detail describing the mass (M17) of the tree (17) or its part, a substantially vertical load (LD) applying to at least one of the following: the wood processing device (20), the feeding means (22) or the delimbing means (24a, 24b), to determine a substantially vertical support force (FS) required for supporting the tree (17) in the wood processing device (20) based on at least one determined substantially vertical load (LD) and to adjust at least one of following when processing the tree (17) in wood processing device (20) for producing said substantially vertical support force (FS): pressing force (PF22) of the feeding means (22) against the tree trunk or pressing force (PF24) of the delimbing means (24a, 24b) against the tree trunk.

9. A control system according to claim 8, characterized in that the control system (30) comprises means for determining a position (PO20) and a state of motion of the wood processing device (20) and that the control system (30) is configured to determine, in addition to a detail describing the mass (M17) of the tree (17) or its part, a position (PO20) and a state of motion of the wood processing device (20) and to determine, in addition to a detail describing the mass (M17) of the tree (17) or its part, based on the position (PO20) and state of motion of the wood processing device (20), a substantially vertical load (LD) applying to at least one of the following: the wood processing device (20), the feeding means (22) or the delimbing means (24a, 24b).

10. A control system according to claim 8 or 9, characterized in that the control system (30) comprises means for measuring a diameter (D17) and a length (L17) of the tree trunk and that the control system (30) is configured to determinea detail describing the mass (M17) of the tree (17) or its part when the tree (17) is being processed in the wood processing device (20) by measuring a diameter (17) and a length (L17) of the trunk of the tree, determining, based on the measured diameter (D17) and the length (L17) of the tree trunk related to the measurement of the diameter (D17), at least one of the following details: a volume detail (VI) of the part of the tree trunk the diameter (D17) of which was measured, or a volume estimate (VE) of the part of the tree trunk where the diameter (D17) of the tree trunk has not been measured, and determining a detail describing the mass (M17) of the tree (17) or its part based on at least one of the following details: a volume detail (VI) of the part of the tree the diameter (D17) of which was measured, or a volume estimate (VE) of the part of the trunk of the tree where the diameter (D 17) of the trunk of the tree has not been measured.

11. A control system according to claim 10, characterized in that the wood processing device (20) comprises a cross-cut device (25) and that the control system (30) is configured to determine a mass estimate (ME17) for the part of the tree trunk where the diameter (D17) of the tree trunk has not been measured based on at least one of the following details: said volume detail (VI) or said volume estimate [VE), to determine based on the mass estimate (ME17) a substantially vertical load (LD) applied to the wood processing device (20) by the part of the tree corresponding to the mass estimate (ME17), to determine based on the substantially vertical load (LD) applied to the wood processing device (20) by the part of the tree corresponding to the mass estimate (ME17) a substantially vertical support force (FS) required for supporting the part of the tree corresponding to the mass estimate (ME 17) in the wood processing device (20), to control the cross-cutting device (25) to cut of the tree (17) the part of the tree not related to said mass estimate (ME17), and to adjust at least one of following for producing the substantially vertical support force (FS) corresponding to the mass estimate (ME17): pressing force (PF22) of the feeding means (22) against the tree trunk or pressing force (PF24) of the delimbing means (24a, 24b) against the tree trunk.

12. A control system according to claim 8 or 9, characterized in that the control system (30) comprises means for determining a detail describing the mass (M17) of the tree (17) or its part to be processed in the wood processing device (20) and that the control system (30) is configured to image the tree (17) or its part before felling said tree (17) and to determine a mass estimate (ME17) describing the mass (M17) of the tree (17) or its part based on the specific weight of the tree species (TSW) of the tree (17) and the imaging of the tree (17) or its part.

13. A control system according to claim 12, characterized in that the control system (30) comprises at least one of the following means for imaging the tree (17) or its part: a camera (41), a video camera (42) or a laser scanning device [43).

14. A control system according to any one of claims 8-13, characterized in that the wood processing device (20) comprises a cross-cutting device (25) and that, as a response to the cutting off of a part of the trunk of the tree (17) being processed in the wood processing device (20), the control system (30) is configured to drop stepwise the substantially vertical support force (FS) required for supporting the tree (17) in the wood processing device (20) by adjusting at least one of the following: pressing force (PF22) of the feeding means (22) against the tree trunk or pressing force (PF24) of the delimbing means (24a, 24b) against the tree trunk, to feed the tree (17) in the wood processing device (20) by said feeding means (22) and as the feed of the tree (17) in the wood processing device (20) proceeds, to keep said substantially vertical support force (FS) substantially constant or to raise it by adjusting at least one of the following: pressing force (PF22) of the feeding means (22) against the tree trunk or pressing force (PF24) of the delimbing means (24a, 24b) against the tree trunk.

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