CA1292924C - Method for limbing, barking and chipping, and a device for utilization of the method - Google Patents

Abstract

A B S T R A C T

A method and a mobile unit for barking and/or limbing and chipping as acontinous operation. A log is given a linear displacement movement by means of a feed unit including two in relation to each other displacable feed rollers in direction towards a chipper , and as first step preceeding the feed rollers, existing branches are removed by a limbing unit including at least two knife-acting means, displacable in relation to each other in a substantially crosswisely extending plane in relation to the longitudinal and displacement direction for the log, pressed against the peripheral surface of same.
During the linear feeding movement of the log, existing branches are sheared or cut off. When performing barking, the feed unit is followed by a rotary barking unit surrounding the log, including a number of barking means with members arranged to take up cutting or frictional contact with the peripheral surface of the log, which by means of centrifugal force during a rotary movement in a plane different from the feeding direction for the log are pressed against the peripheral surface of the log, and by means of a cutting operation remove a layer of bark surrounding the log.

Description

~Z~;~924 The present invention relates to a method for limbing, barking and chipping in a preferably mobile unit, and a device for utilization of the method.

For example, a device is disclosed in US 3 653 417 for removal of limbs and debarking, including a barking unit having a number of pivotally attached barking knives, each one being arranged with an hydraulic cylinder by means of which the barking knives can be pressed against a log and also including a conical member arranged supporting a number of cutters, which when rotated act as a milling cutter, and thus cuts or mills away existing branches from the log. This device is located in an intermediate position between two conveyor belts, which are used to impose a linear movement for the log through the device. A further example of a device is disclosed in SE 398 612, intended to remove branches from a log and chipping of the removed branches.
The log is fed with the larger end portion as a first end portion, and the branches are pressed in direction towards the top of the log and removed, whereafter the branches by means of a conveyor belt with a maintained main direction of movement are moved to a chipper. It is also proposed that the top of the log is cut off, and moved together with the branches to the chipper.
Limbing and barking of the log is performed by means of a rotary limb removing drum, at one end portion having limb cutting and bark removing means peripherally arranged, which by means of a strong rubber band or similar resiliently are pressed against the peripheral portion of the log. These previously known examples of devices are not suitable when, for example, logging in small-tree forests, as when performing thinning, and when relatively small diameter logs are to be transformed into chips.

The present invention provides for limbing, barking and chipping as each other continously following operations, as well as a mobile unit for utlization of the method, and it is particularly well suited for small diameter logs, as obtained during a thinning operation. Adjustment between manufacture of industrial ~k i;~9Z9'~4 chippings, having a minimal content of bark, and chippings for energy purposes, having a larger 1 ,,, - la -lZ9Z92~

content of bark, is also easily performed, as well as adjustment of the barking capacity to the type of trees being proccssed, and existing variations caused by the actual time of year when barking is performed. The method according to the present invention can be utilized in a machine having a simple t~chnical design, which results in dependable operation and low manufacturing and maintenance costs.

The method according to the present invention makes it possible to perform barking and/or limbing and chipping as a continuous operation, and is based on the factor that a log by means of two in relation to each other displacable feed rollers is given a linear displacement movement in direction towards a chipper, at least two knife-acting means are pressed against the peripheral surface of the log in a step preceeding the ~eed rollers, displacable in relation to each other in a ~ubstantially croscwisely extending plane in relation to the longitudinal and displacement direction for the log, which during the linear feeding movement of the log shear or cut off existing braches, and when performing barking, the feed rollers being followed by a rotary barking unit surrounding the log, including a number of barking means having members arranged to take up contact with the peripheral surface of the log, which by means of centrifugal force during a rotary movement in a plane different from the fee~ing direction of the log are pressed against the peripheral surface of the log, and by mens of a cutting or frictional contact operation remove a layer of bark surrounding the log.

Accordingly therefore, the invention provides a method of barking, limbîng and chipping a log which includes the steps of displacing a log linearly towards a chipper by means of feed rollers, shearing branches from the log my means of knife-like means pressed against a peripheral surface of the lZ9Z924 - 2a -log a1: a location preceding the feed rollers and removing bark from the log at a location following the feed rollers by barking means having barking members pressed against the peripheral surface of the log by centrifical force to remove bark from the log by a cutting operation.

The invention also provides a mobile unit for barking, limbing and chipping a log said unit comprising a vehicle, a chiper attached to the vehicle, a log feeding device including two displacable feed rollers for imposing a linear feeding movement on the log in the direction towards the chipper, at least two displacable limbing units located forwardly of the feed rollers in a feed direction of the log for movement towards one another into a substantially embracing relationship with the log, the limbing units including cutting portions directed oppositely to the feed direction of the log for shearing existing branches from the log during feed movement thereof toward the chipper.

The device for utilization of the method according to the present invention includes a vehicle, a chipper attached to the vehicle, and a feeding device including two in relation to each other displacable feed rollers, arranged to impose a linear feeding movement for a log in direction towards the chipper, and at least two in relation to each other displacable limbing units are arranged located before the feed rollers in the feed direction of the log, during a movement in direction towards each other in a plane different from the longitudinal and feeding direction for the log being arranged to take up a substantially embracing contact with the outer portion of the log, and by means of cutting portions directed against said feeding direction cut off or shear off existing branches during the B

~29Z924 feed movement in direction towards the chipper. As further characteristic features can be stated, a barking unit is arranged in an intermediate position in relation to the feed rollers and the chipper, including a drumshaped member surrounding the log, arranged carrying a number of barking means, wh;ch are arranged having members for cutting or frictional contact against the outer peripheral surface of a log, said members being arranged to be pressed against a log by influence from centrifugal force applied against weights arranged by the barking means at a distance from the cutting or frictional contact members.

An embodiment of a device for utlization of the method according to thepresent invention, and certain modifications thereof, will be more fully described below with reference to the accompanying drawings, in which:-Fig. 1 shows a side view of a mobile unit for utilization of the methodaccording to the present invention;

Fig, 2 shows diagrammet1cally the stations for limb1ng, feeding, barking and ch1pp1ng, Fig. 3 shows a cross-sectional view of an embodiment of a limbing unit according to the invention;

Fig. 4 shows ~ plan view of the embodiment shown in Fig. 3, viewed at the sectional line IY - IV;

Fig. S shows a v;ew intended to disclose how two limbing units of the type shown in Figs. 3 and 4 can be arranged located in relation to each other;

Fig. 6 shows a side view in which a feeding device 1s schemat1cally shown, and Fig. 7 shows a v1ew in longitud1nal section of an embodiment of a barking unit according to the invention.

With reference to Fig. 1, an example of a mob11e unit for util1zation of the method according to the present invention is shown, including a lZ9Z924 tractor 1, having a conta;ner 2 t;ltably attached to the rear portion. A
tubular pipe 3 extending above the tractor 1 joins said container 2 with a chipper 4, attached to front end portion of the tractor 1. Sa;d chipper 4 is attached to a barking unit 5, which is preceeded by a feeding unit 6, a limbing unit 7 and an entrance member 8. By the forward end portion of the tractor 1, a device is also attached for lifting the logs to the entrance member 8, formed by a first member 9, pivotally attached attached at a first end portion against the tractor 1 for a movement in the vertical plane when an associated hydraulic piston cylinder 10 is operated, having a second end portion joined to a second member 11 by means of a universal joint 12, whereby said universal joint 12 facil;tates that the second member 11 can be p;voted at will ;n relat;on to the first member 9 in any desired plane of movement.
Adjacent to the free end portion of the second member 11 is an attachment rneans 13 arranged, intended to facilitate seizing of a log, and also a manually operable control member 14, whereby the hydraulic p;ston cylinder 10 can be operated to ra;se and lower respectively the first member g in relation to the ground plane.

When trees are cut down, a conventional limb;ng operation is performed a restricted dlstance along the tree ;n direction upwards before the cutt1ng operat;on is carried out. Such a cut down tree ;s ;nserted into the entrance member 8 with the larger end portion as a first end portion. This operation is advantageously performed utilizing prev;ously mentioned device for lifting logs to the entrance member 8, in wh;ch case the operator by means of the control member 14 performs a lower;ng movement of f;rst member 9 to a pos;tion in wh;ch the attachment means 13 can be secured to the intended log. Since the second member 11 can be pivoted at will in relation to the first member 9, the log in question can thus be located within an area restricted by the radius of movement for the second member 11 obtainable in relation to the universal joint 12 when the first member 9 is located in a substantally horizontally extended position, i.e. a relatively large area. When the operator has attached the attachment means 13 to the ;ntended log, the control member 14 is influenced again, whereby the hydraulic p;ston cylinder 10 performs a movement resulting in a lifting movement of the first member 9 in direction away from the ground plane, which results ~n that the log ~s automatically located in a position adiacent to the entrance member 8, from which feeding can be performed.

The larger end portion of the log, from which branches were removed during the cutt;ng operation, is now inserted between two limbing units 15, 15 to two feed rollers 16, 16 , which preferably have a forced movement in relation to each other, i.e. a movement in direction to/from each other is performed equal in relation to a point at which the feed rollers 16, 16 are located in an adjacent position to each other. When the log has been inserted between the feed rollers 16, 16 , same are pressed against the log by means of a hydraulic piston cylinder or similar, whereafter at least one of the feed rollers 16, 16 is caused to rotate, thereby causing a displacement movement for the log in direction towards the tractor 1.

In connection therewith, the limbing units 15, 15 are pressed against the log by means of a substantially linear displacement movement performed in a crosswisely extending relationship to the longitudinal direction of the log, The limbing units 15, 15 are closely related to two kn~ves, arranged to cut or shear off existing branches at the log when the log performs a linear displacement movement passed the limbing unlts 15, 15 . An example of a suitable embodiment will be described more in detail 1ater.

From the feed rollers 16, 16 , the log is moved to a barking unit 5, which debarks the log, whereafter the log reaches the chipper 4, which is of a conventional type, and includes fan means for accomplishing an air stream by which the chippings can be moved through the tubular pipe 3 to the container 2.

Each other successively following operations will now be described, with examples of embodiments of devices used to perform the operations.

Utilized limbing units 15, 15 are, as previously indicated, comparableto two knives, which can only move in a substantially perpendicular plane in relation to the longitudinal direction of the log, and which during the linear displacement movement of the log cut off existing branches. However, in order to accompllsh adjustment to the actual diameter, each limbing unit 15, 15 comprises preferably of a number of lZ9Z~2~

linkably joined parts, and an example of such an embodiment is shown in F;gs. 3 and 4. According to this example of an embodiment, each limbing unit comprises of three linkably joined knives 17, 17 , 17", the outer knives 17 , 17" being joined by means of a link system 18, 18 to a plateshaped member 19, whereas the centrally located knife 17 is arranged attached to a shaft 20, extending through a hole arranged in the plateshaped member 19. As shown in Fig. 3, the knives 17, 17 , 17"
are arranged hav;ng a curved cross-sectional configuration, and Fig. 4 also shows how the knives 17, 17 , 17" are arranged to form a Y-shaped member as a combination with regard to the configuration of the cutting edge portions. By displacing the plateshaped member 19 and/or the shaft 20 in direction towards a log located between the limbing units 15, 15 , adjustment to actual diameter of the log is performed by all knives 17, 17 , 17" included in a limbing unit 15, 15 , which hereby can be brought to maintain a contact position against the outer peripheral portion of a log, and with a continous and successive adjustment to the variation in the diameter of the log which takes place during the feeding operation of same in direction towards the chipper 4. It should also be noted, that the knives 17, 17 , 17" in a simple way can be moved in direction away from a log, e.g. when the log is manually inserted, by a movement in direction away from the log for the plateshaped member 19 and the shaft 20. The method in which the edge portions of the knives 17, 17 , 17" are arranged having a V-shaped line of extension results in a successive and "soft" cutting operation, and it is also advantageous to arrange the limbing units 15, 15 located in a displaced position in relation to each other in the feeding direction, as schematically indicated in Fig. 5. Required movements of the plateshaped member 19 and the shaft 20 are advantageously accomplished by means of hydraulically operated piston cylinders, but also other means can obviously be used, for example spring means. Furthermore, the limbing units 15, 15 can also be arranged joined by means of a link system or similar, in order to accomplish simultaneous operation of both limbing units 15, 15 .

An example of a feeding unit 6 is schematically shown in Fig. 6, even though said figure basically is intended to disclose how the feed rollers 16, 16 can be arranged connected in relation to each other, in order to accomplish a corresponding and simultaneous movement for the feed rollers 16, 16 in direction to/from each other. Each feed roller 16, 16' is supported by means of pivotally attached supporting link arms 21,21' each of said link arms 21,21' bei.ng joined to a cog wheel 22, 22' adjacent to the attachment points for the link arms 21,21'. The cog wheels 22,22' of an upper and a lower link arm 21,21' are arranged to intermesh with each other, and as a result, the link arms 21,21' perform a corresponding pivoting movement towards and away from each other, whereby the feed rollers 16,16' also perform a corresponding movement. The feed rollers 16,16' lo are preferably pressed against a centrally located log by means of a hydraulically operated piston cylinder 23. When a log is inserted, the hydraulic piston cylinder 23 is operated to perform such a movement, that the feed rollers 16,16' are moved away from each other, whereafter the piston cylinder 23 with a substantially constant pressure maintains the feed rollers 16,16' in a position pressed against a log, while simultaneously at least one fsed roller 16,16' is given a rotary movement, intended to move the log in direction towards the chipper 4, The feed rollers 16,16' are advantageously arranged having a peripheral centrally located surrounding V-shaped groove intended to center a log in relation to the side portions of the feed rollers 16,16'.
Furthermore, the cog wheels 22,22' can obviously be replaced by toothed segments or a link system, arranged to cause a similar movement of the feed rollers 16,16'in direction towards/from each other.

An example of a barking unit 5 is shown in Fig. 7, including - a drumshaped member 24, carrying a number of pivotally attached barking means 25,25'. Said barking means 25,25' are advantageously arranged with varied angular extension in direction from the point of attachment, e.g. substantially L-shaped, and carry adjacent to a first end portion one or a number of cutting members 26,26', and adjacent to a second end portion a counterweight 27,27'. The possibility for the barking means 25,25' to perform a pivoting movement in lZ9;~9Z4 direction towards each other is advantageously restricted, in order to avoid possibllity for the cutting members 26,26' to take up contact with each other when a log is not located in an intermediate position therebetween. The number of barking means 25,25' can obviously be varied, but as an example can four such barking means 25,25' be given as a suitable number, preferably having a substantially similar angular orientation in relation to each other. The drumshaped member 24 is arranged having peripherally located openings, which facilitate that removed bark can be l ' ~

- 7a -1~9~924 thrown out, and may advantageously be arranged including peripherally located fan means, which cause an a;r stream causing removed bark to be thrown out from a housing surrounding the drumshaped member 24 and including an outlet opening, preferably directed towards the ground Iplane. The drumshaped member 24 is caused to perform a rotary movement, whereby the counterweights 27, 27 by means of centrifugal force press the cutting members 26, 26 against an intermediately ;nserted log, which during a linear displacement movement past the surrounding and rotary barking means is debarked. The barking depth can be varied as desired by varying the rotary speed of the drumshaped member 24, whereby an increased rotary speed results in that the cutting members 26, 26-perform a cutting operation with a larger number of revolutions within a specific surrounding peripheral surface of the log, but also that the cutting members 26, 26 are pressed with a larger force. A reduction of the rotary speed will obviously result in reversed conditions. The removal capacity during barking can also be varied by a change of the feeding speed for the log, but such a change may result in negative effects during the successively following chipping operation.

In order to facilitate production of chippings to be used for energy purposes, i.e. when a barking operation is not required, the barking unit 5 may advantageously be arranged to facilitate movement to a position, in which a log can pass in a side relationship to the barking unit 5. The barking unit 5 can advantageously be arranged pivotally attached, in order to facilitate a pivoting movement to such a position, but it may obviously also be arranged to perform a substantially linear movement from its operative position.

Adjacent to the cutting members 26, 26 can also advantageously a cutting depth restricting abutment means be arranged, arranged to restrict removal of material beyond a predetermined barking depth. Such a means can be arranged located adjacently to the cutting members 26, 26 , arranged to take up contact with the outside surface of the log, and only facilitate cutting with a predetermined cutting depth in relation to the point of contact.

The barking means 25, 25 can easily be removed and replaced by other barking means 25, 25 suited for another type of timber or for another lZ9Z9~4 season of year. The possibility to adapt the cutting ability to existing time of the year is most desirable, since a debarking operation is considerably easier to perform in mild weather than during cold winter weather. The possibility to easily replace the barking means 25, 25 makes it also possible to easily perform a sharpening operation or to replace same, which is also extremely desirable, in order to obtain best possible removal conditions.

The barking means 25, 25 are also advantageously arranged having a slightly inclined extension in relation to the rotary axle for the drumshaped member 24, whereby the cutting members 26, 26 also obtain a slightly inclined direction of extension, resulting in that said cutting members 26, 26 not only perform a barking operation, but also result in a force applied against the log and directed towards the chipper 4, in order to obtain a feeding movement of the final portion of the log in direction towards the chipper 4, when said portion is no longer moved by means of the feed rollers 16, 16 .

The bark9ng means 25, 25' can fina11y also be arranged to be influencedby means of an associated spring member to perform a pivoting movement in direction away from each other when the drumshaped member 24 is rotated slower than a predermined rotary speed, in order to simplify insertion of a log between the cutting members 26, 26 .

Accord;ng to the invention, a log can thus in a simple and effective fashion be moved to the entrance member 8, the limbing unit 7 being arranged in open position, i.e. with the included two units 15, 15 separated from each other, and also having the feed rollers 16, 16 located in a separated position, in order to facilitate insertion of the log. The drumshaped member 24 is advantageously arranged rotating with a reduced rotary speed. When a first end portion of the log has been inserted between the feed rollers 16, 16 , a control means is operated, whereby the limbing units 15, 15 are displaced in direction towards each other to a contact position against the log, and the feed rollers 16, 16 are also pressed against the log. When the log is fed into the drumshaped member 24, the rotary speed of same is increased, if previously reduced, whereby the cutting members 26, 26' of the barking means 25, 25 take up contact with the peripheral surface of the log, ~Z5~Z9~4 thus performing the barking operation. The feed rollers 16, 16 continously feed the log in direction towards the chipper 3, while the limbing unit 7 removes existing branches and the barking unit 5 performs debarking. When the feed rollers 16, 16 take up a closely related position, i.e. when the entire log has been fed through, a valve means or a limit switch is advantageously influenced, in order to automatically return the limbing units i5, 15 to an open position, as well as the feed rollers 16, 16 . A reduction of the rotary speed for the drumshaped member 24 can also simultaneously be accomplished.

The embodiments shown and described can obviously be further modified within the scope of the inventive thought and the following claims, and it is obvious, that the limbing unit 7 in its simpliest form may consist of two or more curved knives, arranged to facilitate a radial displacement movement in direction towards a common centre, and necessary contact pressure may for example be obtained from spring members, hydraulically operated piston cylinders or any other suitable pressure means. Furthermore, the barking unit can be designed in a number of fash10ns, while maintaining influence from centrifugal force to press the barking means against a log. Such influence may for example be arranged to stretch slingshaped chains, wires or similar, which also may be arranged carrying cutting barking tools.

It is obviously also possible to avoid barking, e.g. when producing chippings intended for energy purposes, only by disconnecting the rotary drive for the drumshaped member 24, and said drive can be connected again when the log substantially completely has passed the feed rollers 16, 16 , provided that the barking means 25, 25 are arranged inclined to cause a feeding movement, thereby giving the final part of the log a continued feeding movement towards the chipper 4.

Claims (10)

1 A method of barking, limbing and chipping a log which includes the steps of displacing a log linearly towards a chipper by means of feed rollers, shearing branches from the log by means of knife-like means pressed against a peripheral surface of the log at a location preceding the feed rollers and removing bark from the log at a location following the feed rollers by barking means having barking members pressed against the peripheral surface of the log by centrifical force to remove bark from the log by a cutting operation.

2. A mobile unit for barking, limbing and chipping a log said unit comprising a vehicle, a chipper attached to the vehicle, a log feeding device including two displaceable feed rollers for imposing a linear feeding movement on the log in the direction towards the chipper, at least two displaceable limbing units located forwardly of the feed rollers in a feed direction of the log for movement towards one another into a substantially embracing relationship with the log, the limbing units including cutting portions directed oppositely to the feed direction of the log for shearing existing branches from the log during feed movement thereof toward the chipper.

3. A unit according to claim 2 including means for urging the feed rollers toward one another and means for providing complimentary movement of the feed rollers toward and away from one another.

4. A unit according to claim 2 which further includes a barking unit between the feed rollers and the chipper, and barking unit including a drum shaped member for surrounding the log, the drum shaped member carrying a plurality of internal barking members adapted for engaging against the outer surface of the log by centrifical force produced by rotation of the drum shaped member for debarking the log by a cutting action.

5. A unit according to claim 4 wherein the barking members are pivotly attached to the drum shaped member at the respective attachment points and have pairs of arms extending in opposite directions from the respective attachment points, one of said arms being provided with a cutting member and the other of said arms being provided with a counter weight.

6. A unit according to claim 5 wherein the respective arms which carry the cutting members are inclined in relation to the feed direction of the log whereby the cutting members impose a feeding force on the log during the cutting operation for moving the log in a direction toward the chipper.

7. A unit according to claim 3 which includes means for removing the drum shaped member from surrounding relationship to a log whereby a log may bypass the drum shaped member during feed movement toward the chipper.

8. A unit according to claim 2 wherein each limbing unit comprises a plurality of linked knives of curved cross sectional configuration, and a link system for pressing said knives against a a log substantially across the entire cross sectional extension of the knives.

9. A unit according to claim 8 wherein the knives have an overall V-shape cutting configuration and respective means for moving each knife indivually towards and away from a log.

10. A unit according to claim 2 further including an entrance member for the log adjacent the limbing means and a log lifting and feeding means adjacent the entrance member, the lifting and feeding means comprising a pivotal linkage operated by a piston and cylinder assembly, the linkage including a pair of elongated links with a universal joint therebetween and terminating in log attachment means, the configuration of the links being such that the log attachment means may be used to raise a log from ground level to the entrance member.