Note: Descriptions are shown in the official language in which they were submitted.
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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
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chippings, having a minimal content of bark, and chippings for
energy purposes, having a larger
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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,
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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.
