WOOD HARVESTER

ABATTEUR FORESTIER

English Abstract

The invention relates to a wood harvester which
includes a cutting unit. With the intention of provid-
ing a cutting unit which can selectively effect a cutting
operation either by sawing or by shearing, it is pro-
posed in accordance with the invention, among other
things, that the cutting unit includes a pair of shearing
elements (42, 42), of which one can be driven relative
to the other in a first plane between an open position
and a shearing terminal position, and also a saw means
(64) which can be driven in a second plane generally
parallel with the first plane between a rest position and
a saw terminal position, wherein the saw means (64)
when in its rest position is located so close to one of
the shearing elements (42) that in the open position the
clipping element will form a bottom guard for the saw
means (64) before operating the saw means (64) or the
shearing elements (42, 42).

French Abstract

Cette invention concerne une abatteuse de bois qui comporte un dispositif de coupe. Pour que ce dispositif puisse effectuer des opérations de coupe, soit par sciage, soit par cisaillement, il est proposé, notamment, de le munir d'une paire d'éléments de cisaillement (42, 42) se déplaçant l'un vers l'autre dans un premier plan entre une position ouverte et une position extrême de cisaillement, ainsi que d'une scie (64) qui peut être actionnée dans un second plan, en général parallèle au premier, entre une position de repos et une position terminale. La scie (64), en position de repos, est si proche de l'un des éléments de cisaillement (42) que l'élément de préhension, en position ouverte, lui sert de protection inférieure, avant que la scie (64) ou les éléments de cisaillement (42, 42) soient actionnés.

Claims

7
What is claimed is:
1. A wood harvester including a cutting unit, having a pair of wood shearing
elements of which at least one can be driven relative to the other in a first
plane
between an open position and a shearing terminal position, and also a saw
means
which can be driven in a second plane which is generally parallel with the
first plane,
between a rest position and a saw terminal position, wherein the saw means
when in
said rest position is located so close to the shearing elements that said
elements form a
bottom guard for said saw means, at least in said open position, characterized
in that
the shearing elements include a cutting knife mounted in a knife frame, and in
that the
upper sides of the cutting knife and the knife frame lie substantially in the
same plane,
and in that a portion of the knife frame supporting the underside of the
cutting knife
extends convergingly at an acute angle towards the cutting knife in a knife
cutting
direction.
2. A wood harvester according to Claim 1, characterized in that the saw means
includes a saw-guide bar of a chain saw.
3. A wood harvester according to any of the preceding Claims, characterized by
a saw-means cover plate which is spaced by a distance above the saw means.
4. A wood harvester according to Claim 3, characterized in that the cover
plate is
made of spring steel.
5. A wood harvester according to Claim 3 or 4, characterized by support means
which are disposed adjacent the contours of the cover plate and face towards
one of
the shearing elements, the height of said support means being smaller than
said
distance.

Description

~O 95/01094 PCT/SE93/00601
2~6608~
1
WOOD HARVESTER
The present invention relates to a wood harvester
which includes a cutting assembly.
i
Two main methods are used in the forest industry to
separate roots from tree trunks and for cutting tree
trunks in general, namely sawing and shearing. Sawing
is primarily required when logging large-diameter tree
trunks intended for use in timber and pulp production,
where high demands are placed on the quality of the
cut surface, so as to avoid the formation of cracks
and splinters that may impair the raw timber or pulp
material. Shearing is primarily suited for application
with trunks of smaller diameter in conjunction with
forest cleaning-thinning work and energy-wood felling,
and also when cutting or logging large-diameter tree
trunks which have been damaged in some way or another
and which are therewith rendered unsuitable as raw
material for the manufacture of timber and pulp.
Although shearing can often be replaced with sawing,
there are situations when the sawing tool - practic-
ally always a chain saw - is deficient in some way or
another. This applies in particular when the sawing
tool comes into contact with several slender, elastic
trunks or branches, for instance when cutting the
crowns of birch trees or the tops of spruces, which
tend to seize, stop and possibly damage a saw chain.
35
An object of the present invention is to provide a
wood harvester of the aforedescribed kind whose cut-
ting unit is able to effect a cutting operation either
by sawing or by shearing, therewith avoiding the
aforesaid drawbacks and affording a greater degree of
freedom.
This object is achieved with the characteristic fea-
tures set forth in the following Claims.

CA 02166085 2003-05-13
2
In accordance with one aspect of the present invention there is provided a
wood
harvester including a cutting unit, having a pair of wood shearing elements of
which
at least one can be driven relative to the other in a first plane between an
open
position and a shearing terminal position, and also a saw means which can be
driven
in a second plane which is generally parallel with the first plane, between a
rest
position and a saw terminal position, wherein the saw means when in said rest
position is located so close to the shearing elements that said elements form
a bottom
guard for said saw means, at least in said open position, characterized in
that the
shearing elements include a cutting knife mounted in a knife frame, and in
that the
upper sides of the cutting knife and the knife frame lie substantially in the
same plane,
and in that a portion of the knife frame supporting the underside of the
cutting knife
extends convergingly at an acute angle towards the cutting knife in a knife
cutting
direction.
The invention will now be described in more detail with reference to an
exemplifying
embodiment thereof and also with reference to the accompanying drawings, in
which
FIGURE 1 is a top view of a bottom part of a wood harvester according to the
invention; FIGURE 2 is a side view of the harvester illustrated in FIGURE 1;
FIGURE 3 is a top view of a modified version of the harvester illustrated in
FIGURE
1 and shows the harvester in a shearing terminal position; FIGURE 4
illustrates a
modified version of the harvester illustrated in FIGURE 1 and shows the
harvester in
a saw terminal position; and FIGURE 5 is a schematic sectional view taken on
the
line 5-5 in FIGURE 4.
The inventive wood harvester 10, which is shown only partially in the
drawings, is
intended to be fitted to the crane; arm of; an excavating machine or digger
for instance,
and include a bottom frame part 12, which in the illustrated embodiment
extends at an
angle from a vertical centre beam 20 on the harvester. It is assumed that a
pair of
gripping arms and optionally also a trunk-gathering device, for instance of
the type
disclosed in US-A 5.08,595, are mounted in a

O 95101094 ~ PCT/SE93/00601
3
known manner on that part of the central beam 20 which
is ;not shown in the drawing.
6
The illustrated harvester 10 is also constructed as a
so-called tree piucker and is provided with a ground
l
support 14 whioh is able to thrust against an underly-
ing surface 80 and fell or cut a tree grasped by the
gripping arms (not shown) through the agency of a
lever-arm effect, by plucking the tree from the ground
with its root attached, which is another tree harvest-
ing method. However, the invention can also be applied
advantageously with wood harvesters that lack the
provision of a ground support 14.
Mounted close to the bottom end of the frame part 12,
in the vicinity of the ground support 14, is a cutting
unit 30 which, in accordance with the invention,
includes a shearing device 40 and a saw means in the
form of a chain saw 60 mounted closely above the
shearing device.
The shearing device 40 includes a pair of shearing
elements 42, 42, each of which comprises a relatively
thick knife-frame 44 and a relatively thin shearing or
cutting wedge or knife 46, which is secured to the
kni:Ee-frame 44 by means of screw joints 48. As will be
seen from FIGS. 2 and 5, the upper sides of the knife-
frame 44 and the cutting knife 46 lie essentially in
mutually the same plane, so that the relatively thick-
er knife frame 44 projects down beyond the underside
of the cutting knife 46. In this way, which is the
reverse to conventional shearing devices, the shearing
device 40 obtains a generally flat upper side which
enables the chain saw 60 to be placed very close to
the shearing device 40 and therewith. protected by said
device from beneath, and also enables the upper side
of the shearing device to serve as a flat supportive
surface for several trunks when using the aforesaid
trunk gathering function. As indicated in FIG. 2, the

WO 95/01094 PCT/SE93I00601
4
"reversed" positioning of the knife frame 44 of the
shearing device 40 will not, in practice, present an
obstacle to cuts that are made close to the root of
the tree, since the ground part 84 which embraces the
root-end of the tree 82 to be felled will normally
y,
slope downwardly and outwardly from the tree and
thereby leave space for the downwardly projecting
knife-frame 44, even when cutting the tree close to .
its root. In order to ensure that the downwardly
extending parts of the knife-frame 44 will not prevent
the shearing elements 42, 42 from closing, for in-
stance by coming into contact with the edges of up-
wardly turned cutting surfaces on the tree, those
sides 43 (only one of which is shown in FIG. 5) of the
knife frame 44 that border on the cutting knife 46
converge at an acute angle towards the cutting knife
46 in its cutting direction, so that they can slide
more easily past such edges.
Each of the two shearing elements 42, 42 are pivotally
journalled on a respective journal shaft 22 (only one
of which is shown in FIG. 2), the upper end of which
is connected to a tree-capturing plate 26 (see also
FIG. 1), which in turn is connected to the frame part
12 via a reinforcing plate 24, and the bottom end of
which is connected to a bottom plate 18 on the ground
support 14, via a bearing attachment 28. The bottom
plate 18 forms a large abutment surface against the
underlying support, and also provides protection for
the hydraulic piston-cylinder devices 50, 5o against
irregularities in the underlying support surface 80.
The two shearing elements 42, 42 are driven for pivot-
al movement about their respective journal shafts 22 ,
between an open position (FIG. 1) and a shearing
terminal position (FIG. 3) by a respective hydraulic
piston-cylinder device 50, for instance for severing a
bouquet of a plurality of more slender tree trunks or
stems 86. One end of respective hydraulic devices 50

~O 95101094 PCT/SE9310060I
is pivotally journalled on one outer surface of the
ground support 14 while the end of the piston rod of
each hydraulic device is pivotally journalled to a
rear, outer corner of respective shearing elements 42.
5 In addition to severing slender stems, the shearing
device is better suited than a chain saw for cutting
large-diameter untrimmed trunks, the branches of which
are liable to guide a saw-guide bar away from the
intended cutting plane, with possible damage to the
chain saw as a result.
The chain saw 60 may be comprised of a known saw unit,
having a saw-guide bar 64 which for cutting, e.g., a
tree trunk 82 is constructed so as to be swung out and
in between a rest position (FIGS. l, 3) and a saw
terminal position (FIG. 4) in a saw guard, such as a
saw box 62.
As illustrated in FIGS. 4 and 5, instead of a saw box,
the saw-guide bar 64 may be covered in its rest posi-
tion by a cover means having the form of a spring-
ste~el blade 62', adjacent the contours of which there
is provided one or more support or abutment devices 63
which face towards the shearing element. In the illus-
trated embodiment, the abutment devices 63 are formed
integrally with the steel blade 62' in the form of
angled flaps, although they may also extend in the
form of a single rim along the rear and outer side
(not shown) of the blade 62'. The undersurfaces of the
abutment devices 63 are spaced from the upper side of
the shearing element 42, so that when the upper side
. of 'the steel blade 62' is subjected to blows and
impacts, it will perform a resilient or damping move-
- ment before the abutment devices 63 strike the upper
surface of the shearing element 42, and therewith
prevent the blade 62' from coming into contact with
the saw-guide bar 64 and the saw chain (not shown).

WO 95/01094 PCT/SE93/00601
6
The guide bar attachment 66 of the guide bar 64 is
pivotally mounted on the underside of an opposing
wood-catching plate 24', which is larger than the
wood-capture plate 24 and to which the aforedescribed
cover means 62' is attached. The saw chain (not shown)
of the saw-guide bar 64 is driven by a hydraulic motor
68 mounted on the upper side of the plate 24'. Pivotal
movement of the saw-guide bar 64 between the rest
position and the saw terminal position is effected by
means of a setting device 70, e.g. a hydraulic piston-
cylinder device, mounted between the guide bar attach-
ment 66 and the plate 24'.
Because the sawing movement of the saw-guide bar 64 is
effected by a pivotal movement from outside and in
towards the wood harvester, as illustrated in FIG. 4,
the tree can be held by the gripping arms (not shown)
of the harvester during the root separating sawing
action, and thereby be subjected to a force that acts
towards the harvester without risk of the guide bar
and saw chain being clamped between the cut surfaces
during a cutting operation.
When in its rest position and at least when the shear-
ing device 40 is in its open position, the chain saw
60 with saw-guide bar 64 is protected by the underly-
ing shearing element 42 against contact with the
underlying support surface 80 and with stones and the
like protruding from said surface. As illustrated in
FIG. 3, the frame part 44 of said shearing element 42
may alternatively extend in the form of the sector of
a circle 44', so that the saw-guide bar 64 will be ,
protected even in the shearing terminal position.
____________________

Representative Drawing