Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to an apparatus
for crushing stumps and other felling waste into chips.
Owing to an increasing shortage of wood fi~re
raw material in forests in relation to the incxeasing demand
in the world, the wood countries have for the last years tried to
utilize a greater part of the tree than had earlier been the case.
In this respect the attention has particularly been directed to
the tree stumps, mainly since the stumps and also the roots give an~
essential wood fihre addition of high pulp quality. A number of
devices for stump removal (stump extraction) have been developed.
In connection with or after the removal of the stump out of the
ground a first dividing of the stump is carried out in order to
make it together with its root system more readily workable.
The divided stumps have up to now been transported
on a cross-country transport vehicle to a central location
adjacent a road, from which location the further transport up
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to cellulose factories has been made by motor lorries or trucks.
In the cellulose factories the stumps have heen treated in
different ways in order to remove earth and stones prior to
the machining into chips. Above all two disadvantages, however,
exist by such a transport and chipping. One disadvantage is
that the stump portions with their projecting roots do not
give a solid mass percentage that is sufficiently profitable for
the load volume of the transport vehicles. mhe second
disadvantage is the relatively large quantity of earth and
stones in the irregularities and projections of the stumps. Also
ingrown stones exist. The cellulose factories only allow a
small part of these impurities to be extant on the stumps upon
delivery.
An apparatus according to the invention substantially
eliminates both these disadvantages and the invention is
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accordingly an important link in the total work for utilizing
the fibre raw material of the stumps. By using an apparatus
according to the invention not only stumps can be utilized but
also felling waste such as branches, limbs, tops. According
to the invention the disintegration takes place out in the
terrain in connection with stump extraction wherein
simultaneously stones and other impurities in tne stumps are
removed so that chips substantially free from impurities are
obtained.
In general terms, the present invention provides a
mill for crushing tree stumps comprising a rotor housing, a
rotor mounted for rotation in said housing about a substantially
horizontal axis, drive means for rotating said rotor, a
plurality of rotor blades spaced along the rotor on a helical
- path, a plurality of stator blades spaced substantially
axially along the housing interior, rotation of the rotor
causing said rotor blades to pass between pairs of said stator
blades to crush stump material therebetween and liberate
foreign matter from the resulting crushed material, with the
helical disposition of said rotor blades causing said crushed
material and liberated foreign matter to advance substantially
axially along said housing toward one end thereof, and means
for discharging said crushed material and liberated foreign
matter from said one end of said housing.
In accordance with a further feature of the present
invention, said means for discharging the crushed material and
liberated foreign matter comprises a separating means including
a blow device for the crushed material. The mill may also -
include a vibratory delivery device for feeding tree stumps into
said housing. The delivery device preferably has a support
surface inclined downwardly toward said housing. ~-
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In accordance with yet another feature of the
present invention, the rotor ~lades and said stator blades
have respective crushing surfaces ~etween ~hich the stump
material is crushed, the crushing surfaces of the rotor
blades forming an angle with the crushing surfaces of the
stator blades as the rotor blades pass therebetween. According
to yet another feature of the present invention, said rotor
blades each have a crushing surface defining at least one
cutting edge.
An embodiment of the invention is by way of example
described in the following with reference to the accompanying
drawings in which:
Fig. 1 illustrates a process from stump extraction
to vehicle transport of finished crushed chips.
Fig. 2 is a top view of an apparatus according to -
the invention.
Fig. 3 shows the apparatus of Fig. 2 along section
III-III in Fig. 2.
Fig. 4 and 5 is a side view and a section along line
V-V in Fig. 4, respectively, illustrating various forms of
rotor kni~es arranged in an apparatus according to the invention.
Fig. 1 illustrates schematically a process for
collecting stumps and for crushing the stumps into chips before
truck transport to a cellulose factory or a heating plant for
wood burning. The stumps 1 are extracted from the ground and
cut into two to four parts by a stumper 2 in a manner known
per se. The stumper puts down the stump parts 3 in stacks 3a
in a row-like system. A stump forwarder 4 then transports, in ~-
respect of time unfettered by the operation of the stumper, the
stump parts to a central stump stock 5 at a place adjacent a
road R. An apparatus according to the invention is located
adjacent the stump stock 5. The apparatus, which likewise as
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to its operation in respect of time i5 unfettered by other
machines, comprises a stump crush mill 6 provided with
vibrating stone-separating feed table 7. The stump crush
mill 6 disintegrates the stump parts 3 into crush chips. A
stone-separating blow device 8 for the chips is arranged at the
out-feed end of the crush mill in such a manner, that the chips ;
are blown out in controlled direction by a blow nozzle 10,
whereby the chips can form a pile 11 which in view of space
can be considerably high relative to its spreadin~ on the
ground. The piled chips ll are fetched by for instance a
truck 12 which transport the chips to a factory or other
user.
Figs. 2 and 3 show more in detail an apparatus
according to the invention. ~he stump parts 3 are placed on
the feed table 7 by a loading device (not shown) and the feed
table 7 is vibrated in vertical direction. Owing to the fact
that the feed table, as shown, is inclined towards the in-feed
funnel 13 o the crush mill 6, the stump parts 3 will be success-
ively moved to~ards the funnel 13 and fall down on a mill
rotor 14 arranged at the bottom of the funnel 13. The mill
rotor is provided with helically spaced rotor blades 15,
which engage the stump parts 3 and crush them against counter
tools stator blades 16 so that chips are obtained. As shown in
the drawings the stator blades are spaced axially along the
mill housing and the rotor blades pass therebetween on
rotation of the rotor. Owing to the cutting edge form of
the rotor blades and the helical location thereof on the
rotor 14 the chips are fed along a cylindrical rotor house 17
adapted to the form of the rotor blades 15 and out into an
outfeed device 1~. The outfeed device 18 feeds the chips into
the blow device 8, which according to blow trap principle
separates heavier particles (in this case stone splinters
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passing the mill 6) and blows the chips to the stone-free
pile 11.
Coarse and external stones as well as earth have
already been removed from the stump parts 3 when they pass
over the feed table 7. During the vibration of the feed -
table in order to feed the stumps parts into the mill, stones
and earth are shaken off and fall down to the ground between
the latticed bars l9 forming the feed table 7 and arranged ;~
along the feed direction. -~
For the drive the mill can be provided with a
combustion motor 20, if the mill is to be mobile. The mill
can, however, alternatively be provided with an electric motor
in case the plant shall be stationary. In a mobile
embodiment the mill can alternatively be placed for instance on
a trailer, a truck, a forwarder or the like for increased
mobility and capacity. ;~
As is evident from Fig. 4 the crushing surfaces of
the rDtor blades 15,15a, 15b, respectively, can have different
angles of action ~ relative to the crushing surfaces of the
stator blades 16, viz. as shown for the rotor blades 15b an
angle ~ directed towards the rotor 14 when the crushing
surfaces pass for the rotor knife 15a an angle ~ =0 and
for the rotor knife 15 an angle ~ directed away from the rotor.
As is evident from Fig. 5 the crushing surfaces
of the rotor blades 15 can have a different shape, viz.,
as shown at a, a groove with two protruding cutting edges,
at b, a straight cutting shape, at _, double chamfers
narrowing the effective cutting edge~ at d, a chamfer forming
a single cutting edge at one side, at e, double chamfers
forming a pointed cutting edge centrally positioned, and at
f a chamfer forming one pointed cutting edge disposed at
the opposite side relative to d.
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The present invention is not limited to the
embodiment described above and shown on the drawings, but
can be varied in several ways within the scope of the `~
following claims. Thus, a conveyor can for instance be ~
arranged as a discharge device or conveying the crushed , `
chips from the crush mill. Moreover, means can be arranged
for controlling the number of stumps fed into the crush mill,
for instance means for switching off temporaril~ the vibration
of the feed table.
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