AU2003268889B2 - Debarking - Google Patents

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S):: Partek Forest AB ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Nicholson Street, Melbourne, 3000, Australia INVENTION TITLE: Debarking The following statement is a full description of this invention, including the best method of performing it known to me/us: 5102 P 0PER\MIRF\Specificalion\2mm'i2W(~~spciamn,,d 97o:IM420 Debarking This invention concerns a method of debarking a tree, a device for debarking a tree, and a system which includes such a device. 5 In the processing of felled trees, much of the time is taken up in debarking the tree trunks where it is needed. Different methods and means of carrying out this work have been introduced, most of them intended for manual debarking but there are also stand-along units where each tree is debarked after felling and/or after trimming. Debarking has traditionally been carried out with knife-like devices that peel off the 10 bark as they move along the length of the tree. According to a first aspect of the present invention, there is provided a method of debarking a tree, wherein a tree is fed through a device comprising one or more knives acting on the tree, and the knives are powered with pulses to be moved under and out of the bark of the tree, essentially in a radial direction, according to a variable 15 pattern. According to a second aspect of the present invention, there is provided a device used for debarking a tree, comprising a feeder for feeding the tree through the debarking device, one or more knives arranged to act on the tree, and a frequency controlled power source, wherein the knives are arranged to be powered with pulses 20 from the power source to be moved in and out of the bark, in an essentially radial direction, according to a variable pattern. According to a third aspect of the present invention, there is provided a system comprising a device according to the second aspect and further comprising an arm construction supporting the device in order to allow the device to assume varying 25 working positions. Preferred embodiments of the present invention provide a method and a means that make it possible to automate and make more efficient the actual debarking process. The debarking work may be simplified, less time-consuming and cheaper. The debarking device may be simplified, more functional and cheaper. This 30 will make processing the tree less time-consuming and therefore cheaper. The invention will be described in more detail here with references made to Fig 1 and Fig 2, which show a schematic and perspective view of a device according to a preferred embodiment of the invention.

P30PER\AIRF\Specincationsurl 23M r speci amncd 97 doc.14i/4/2)9 -2 A device according to a preferred embodiment of the invention comprises a tree processing unit. The tree processing unit comprises a stand 1 and a feeder mounted on the stand 1. The feeder comprises two or more feed rollers 2, which grip on each side of the tree trunk 3 to feed it forward. The tree trunk is held against the 5 stand 1 by the feeder rollers 2 and a number of guided knives 3. The knife edges are essentially aligned along the length of the tree trunk. The tree processing unit is intended to be suspended from a crane arm using a coupling device 4. The crane arm can constitute, for example, part of a forestry machine/vehicle. 10 The tree processing unit also comprises a means of cutting 5 to cut the tree trunk in suitable lengths and a number of hoses 6 for transporting propellant, which itself enables the work of the feeder rollers 2, the means of cutting 5 and the knives 3. In its presented embodiment, the unit comprises also a trimming knife 7, which in itself is already known and which at position 8 is journalled in the stand 1, and via a 15 compression spring 9 is pressed against the tree trunk. Each knife 3 is pivot-mounted by the use of a bearing sleeve 10 around a pivot pin (not shown in the figure) fastened to the stand 1. Each knife 3 is operated using a piston-cylinder unit 11. The piston-cylinder unit 11 can be hydraulic or pneumatic. The piston-cylinder units act between the stand 1 and the knives 3. 20 The tree processing unit comprises also an impulse sensor, which itself is already known, for measuring the length of the tree trunk so that it can be cut in measured lengths. The knives 3 are used to debark the tree trunk. By varying the pressure, pulsing the pressure, in the piston-cylinder units, the knives 3 can be activated and 25 controlled, operated, in such a way that they are pressed in under the bark of the tree trunk. The knives 3 are powered with impulses according to a variable pattern. In a first stage, a pressure is applied on the knives 3 so that they are pressed under the bark on the tree trunk. The pressure on the knives 3 is then reduced which, in combination with the tree trunk continuing its movement in the feed direction of the 30 device, reduces the friction. This movement of the knives 3 can take place at a predetermined frequency that is registered/entered in the tree processing unit control system. The pulsing frequency of the knives 3 can also been changed/varied while work is in progress. The pulsing frequency can be varied for each knife 3 separately.

P"OPER\MRF\Spcificaionsswik 23te(W specI nend (N 1doc- I 4,4/k)9 - 2a While debarking is taking place, the feeder rollers 2 will operate at full pressure and almost constant feed rate, which means that debarking is done rapidly with continuous feed. The pulsating action of the knives can start at the same time as the feed of the 5 tree or it can be delayed in relation to the start of the feeder so that the feeder function of the unit has come up to speed before the pulsation of the knives 3 is activated. It is possible to start the pulsation of the front and rear knives at different times. If the pulsation of the front and rear pairs of knives respectively is not done in phase but in some form of reverse phase, the friction between the tree processing unit and the tree 10 trunk will be reduced and the feed of the tree trunk through the unit will be affected insignificantly. The pushing or pulling return action of the knives 3 can also be achieved using for example tensions springs fastened to the bearing sleeve 10 and the stand 1 respectively. Double-action piston-cylinder units can also be used for this purpose. 15 The control system need not comprises a hydraulic system. It can also comprise a pneumatic, electric, mechanical or any other type of system that is suitable for the purpose. A method is thus obtained that makes debarking simple, quick and cheap. The means of debarking is simplified and becomes functional and cheap. This will make 20 processing the tree less time-consuming and therefore cheaper. Tree processing is also made safer. Each movement of the tree trunk in conjunction with tree processing is time consuming, sometimes also space-consuming and also constitutes a safety hazard when it must be moved between different devices/units. If a tree processing unit is 25 equipped with one means of debarking and one means of trimming, or if these two functions can be integrated 3 in the same device, a tree trunk being processed with a method and in a tree processing unit according to our invention need not be moved between at least two different devices where one 'of them does the debarking and the other does the trimming but all processing can be done in one and the same tree processing unit. So that the knives on the device can be used 5 for debarking and trimming, the control system should be provided with different control sequences for the two processes and the possibility to reposition the knives. In cases where the tree processing unit also comprises a means of cutting the tree trunk, the time-saving will be even greater. Several different components are shown on the drawing, which are certainly 10 essential to the function of the unit but are not significant to the invention as such. This description is not to be regarded as a limitation of the invention but as an example to facilitate its comprehension. Many different embodiments, designs and similar alternatives are possible within the idea of invention. 15 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Claims (16)

1. A method of debarking a tree, wherein a tree is fed through a device comprising one or more knives acting on the tree, and the knives are powered with 5 pulses to be moved under and out of the bark of the tree, essentially in a radial direction, according to a variable pattern.

2. A method of debarking according to claim 1, wherein the power to the knives is started at the same time as the tree feed is started. 10

3. A method of debarking according to claim 1, wherein the power to the knives is started a variable time after the tree feed is started.

4. A method of debarking according to any one of claims 1 to 3, wherein each 15 knife is controlled individually.

5. A method of debarking according to any one of claims 1 to 4, wherein the knives are powered by a hydraulic system. 20

6. A method of debarking according to any one of the claims 1 to 4, wherein the knives are powered by a pneumatic system.

7. A device used for debarking a tree, comprising a feeder for feeding the tree through the debarking device, one or more knives arranged to act on the tree, and a 25 frequency-controlled power source, wherein the knives are arranged to be powered with pulses from the power source to be moved in and out of the bark, in an essentially radial direction, according to a variable pattern.

8. A device according to claim 7, wherein one bearing axis of each knife enables 30 the knife to be rotated.

9. A device according to either one of claims 7 and 8, wherein the power source comprises one or more piston-cylinder units, arranged to act on and engage P'OPE N IRF\Spccificaions\2,x)\12,,6M6( speci amncd (97 do-1404/2I 19 -5 respective knives to make each knife move into and out of the bark on the tree.

10. A device according to claim 9, wherein the piston-cylinder unit is hydraulic. 5

11. A device according to claim 9, wherein the piston-cylinder unit is pneumatic.

12. A system comprising a device according to any one of claims 7 to 11 and further comprising an arm construction supporting the device in order to allow the device to assume varying working positions. 10

13. A system according to claim 12, wherein the device is connected to an outer free end of the arm construction.

14. A system according to claim 12 or 13, where the arm construction constitutes 15 part of a forestry machine/vehicle.

15. A method of debarking a tree substantially as hereinbefore described with reference to the drawings and/or Examples. 20

16. A device for debarking a tree substantially as hereinbefore described with reference to the drawings and/or Examples.