Note: Descriptions are shown in the official language in which they were submitted.
3319
~OG MILLING ~PPARATUS
This invention relates to a log milling apparatus and par-
ticularly to an improved apparatus for millin~ logs of the type
which are gained from the lower part of the trees and there-
after sawn to form boards.
BACK GROUND 0~ THE INt~E~TIO~
The logs which after adaptation and cross cutting are
gained from the lower part of a tree are named root lo~s. Such
root logs present particular swellin~sor enlargements, so called
root legs, at their lower portion connected to the root system
of the living tree. When a root log is to be sawn for instance
in a frame saw these swellings may cause troublesome problems.
Thus it often happens that the swellings or parts thereof are
thrown loose and smash saw blades, blocks and clamping mea~s
included in the saw frame. The consequence of such incidents
will be stoppage with the ensuing economical loss. Even if
damages on the sa~ frame itself would occur at times only the
mere presence of the swellings brings about othex considerable
disadvantages. ~y the fact that the swellings may project
rather marked outside the normal conicity or the normal mean
diameter of the log at the root or butt end thereof the saw
frame has to be designed with very large dimensions in order
to be capable of receiving not only that portion of the thic~est
log which gives a yield in the form of boards but also the rim-
shaped portion jointly formed by the root swellines. This meansthat the saw frame becomes rather heavy, what in turn means that
the frame can be driven with a rather limited speed only.
In order to eliminate the above mentioned disadvantages it
is ,previously known to mill off the root swellings before sawing
the lo~. One type of apparatus used for this purpose includes
an annular or cylindrical rotatable tool which is provided with
cutting members located on the inside of the tool body and
- through which the log is fed while being hela by a feed assembly.
This feed assembly supports the log at the opposite ends thereo~
~1~3319
and moves it i~ the length direction theraof throuehsaid tool
which is rotated in order to carry out the milling. ~uch appa-
ratus i9 known for instance by the Swedish patent specifications
363 755 and ~86 852 as well as the I~orwegian patent specifi-
cation 129 668. Another apparatus for the same purpose is
known by the Ger~an Offenlegungsschrift 2 813 159 which dis-
close~ a tool having its cutting members located on the outside
of the tool body. Also in this case the log is fed past the
tool by means of a feed assembly supporting the log at the
opposite ends thereof, though in this case allowing rotation of
the log relative to the tool. Common to these two ty-pes of log
milling apparatus is however that the log portion machined by
the tool is always cylindrical because the feed assemblies
define a cer-tain center line in the log and irrespective of
whether the log is rotated or not the tool works in a circular
path around this center line and leaves a finished log portion
of cylindrical shape as the log passes the tool, Since timber
logs are often at least slightly conical rather than cylindrical
this means in practice that the yield achieved by the prior art
apparatus is limited in so far as not only the swellings are
removed from the logs but also the yieldable wood material
defined by the difference between a conical and a cylindrical
shape of the log portion machined. Another disadvantage of the
prior art apparatus is a relatively low production capacity.
S~RY OF ~E I~ENTIO~
It is a general object of the present inv0ntion to provide
a log milline apparatus for removing the swellin~s occuring at
the buttends of root logs, which apparatus guarantees a maximum
yield rrom each log irrespective of the shape thereof while
efficiently removing undesireable root swellings from the logs.
Another object of the invention resides in the provision
of an spparatus having a high production capacity.
A further object is to provide an apparatus which is
capable of receiving from a supply of unsorted logs~ lo6s from
which root swellings are to be milled off as well as logs having
no root swellings and then rapidly dischsrge the latter logs
from the apparatus.
These and other objects and advantages are achieved by
a log milling apparatus comprising
means for reoeiving and supporting a log with the swelled
root end thereof overhanging therefrom, said receiving
means having spaced apart first and second ends defining
the length thereof,
mean~ for ur~ing said log against said receiving means so
as to hold said log in a firm grip resisting forces app-
lied to said overhanging root end of said log,
means for rotating said log about itself as well as relative
to said receiving means and said urging means, and
a cutter arranged beside said receiving means and on sub-
stantially the same side of said log as said receiving
means so as to machine said overhanging swelled root end
of said log along a line which is located in the extension
of the length of said receiving means and on the same side
of said log as said receivine means.
BRI3F DESCRIPTION OF THE D~AWINGS
In the drawings
Fig. 1 is a hori20ntal view frcm above of the apparatus
according to the invention,
Fig. 2 a vertical elevational view o~ the same apparatus,
Fig, 3 an enlar~ed transverse sectional view III-III of
Fig~ 1,
Fi~. 4 a transverse sectional view IV-IV of Fig. 1 likewise
enlarged but cut off at the top,
Fig. 5 a partially cut longitudinal ~ectional view of a
cutter unit included in the apparatus, and
Fig. 6 a transverse sectional view VI-VI of Fig~ 5.
. ~23~1~
DETAILED DESCRIPTION OF T~E PREFERRED EMBODIMEN~
As appears from Figs. 1 and 2 the apparatu~ of the inven-
tion comprises a receiving ~eans generally designated 1 which
has two functions, namely supporting a root lo6 2 and bringine
the same to rotate. A rotatable mill or cutter unit 3 provided
with e~ternal working elements is movable towards and away from
a log butt end portion 2' which overhangs from the receiving
means 1. The swellings or enlargements occuring on this butt
end of the log are indicated by the reference numeral 60.
~ne receiving means 1 comprises two spaced apart V-shaped
supports 4 and 5 defininOE first and second ends of said recei-
ving means. These V-shaped supports support the log from below.
Above the supports there is an urging means in the shape of a
holder-on 6 which is movable towards and away from said supports.
~nis holder-on 6 is arranged to urge the log 2 against the sup-
ports in order to hold the logs in the position indicated with
dashed lines in Fi~. 2, the force applied to the log by the
holder-on being great enough to resist forces applied to the
overhangine root end 2' by the cutter unit 3. rrhe holder-on 6
is movable in a substantially vertical plane located between
the two supports 4 and 5 as indicated by the double arrow A in
Fig. 2. It snould be noted that the plane of movement of the
holder-on is located at a distance not only from the first
support 4 but also from t'ne second support 5, though the latter
di~tance is rather small.
Fig, 3 illustrates that the support 5 (like the support 4)
comprises two endless chains 7, 8 each extending between a
pair of spaced apart ~procket wheels 9, 10 and 11, 12 respec-
tively (see also FiS~. 1 and 2). ~Ot}l of these chains may
advantageously be provided with suitable dogs 13. The sprocket
wheels 9, 10, 11 and 12 are supported by a vertical plate 14
which in turn is supported by a 1ongitudinal foundation 15
included in the apparatus. Gne pair of sprocket wheels 9, 10
is located on one side of said plate 14, while the other pair
of sprocket ~heels 11, 12 is located on the opposite side of
3319
said plate, The two sprocket wheels 9 and 11 are displaced up-
wardly and outwardly in relation to the wheels 10 and 12 respec-
tivel~ so that the two upper parts of the chains 7 and 8 are
inclined while forming~ a V-shapedconfiguration being suitable
for receiving the log 2 which in Fig. 3 is shown by the two
dash-lined circles 2" ~nd 2"'which indicate that the log may
have a high]y varyine diameter. In the upper portion of eaoh
plate there is a V-shaped recess 14".
The two sprocket wheels 10 and 12 at each support 4 and 5
are in this case fixed to a rotatable drive shaft 16 extending
along the length of the receiving means, said shaft being
arranged to jointly drive all of the chains 7, 8 in one and the
same tangential direction of movement, ~ore precisely the chains
shown in ~ig. 3 are arranged to be driven with their upper or
receiving part moving rightward in the drawing. The shaft 16 is
advantageously driven by an electric motor 17 throush a ~earing
18.
~or removing the log 2 from the receivine means after
machining the log or for removing such logs which has been fed
into the machine but which should not be machined,there are
provided a number of ejecting means 19, 20 spaced apart along
the length of the receiving means, said ejecting means being
pivotable between an inoperative position below the lo~ and
an operative position in which it is angularly displaced at
least 90 relative to the inoperative positi~n. The ejecting
meansjsimply consist of arms which are fixed to a common
rotatable shaft 21, The shape of the arms is such that in the
inoperative position they are housed below the imaginary V-
shaped channel which is constituted by the pairs of chains
7, 8, said arms having a recess 22 for housing the shaft 16
driving the chains. Just the two arms 19 are furthermore
pivotally connected to piston-cylinder mechanisms 23 provided
for carrying out the movement of the ejecting means from the
inoperative position to the operative position. ~ne means 20
in turn may advantageously consist of more or less simple
1~3319
plates which are designed with an arcuate circumferential part
24 which is concentric to the rotatable shaft 21. These arcuate
parts 24 of each of said means 20 has the purpose of preventing
unintentional char~ing or feeding in logs to the receiving
means when the ejecting means are moved to their operative
position.
The shaft 16 as well as the shaft 21 are advantageou~ly
mounted in bearines in the plates 14 of the supports 4 and 5.
In the embodiment shown there is a further supporting plate 14'
at that end of the receiving means which is remote from the
cutter unit 3, said further supporting plate being arranged
for mounting the ends of said two shafts,
As best illustrated in Fig. 3 the above mentioned holder-on
6 comprises a yoke 25 having three sprocket wheels 26, 26' and
26". These sprocket wheels, which are triangularly located,
jointly support an endless chain 27 whlch like the ohains 7, 8
advantageously have suitable dogs, The chain 27 has a down-
wardly facing substantially horiæontal part 27' arranged to
be applied to the log 2. Another part 27" is acted on by a
resilient piYotable shoe 28 which always tends to stretoh the
lower part 27' and against the action of which the latter part
is deflectable in order to be adapted to different sectional
sizes of the log 2. The resilience of the shoe 28 is reali2ed
by means of spring means 29. The sprocket wheel 26' is rotatable.
in order to drive the chain 27 in the same tangential direction
of movement as the chains 7, 8 of the supports 4, 5, As appears
from Fig. 2 the rotation of saidsprocket wheel 26" is attended
to by a motor 31 supported on a frame 30, said motor being
connected tosaid sprocket wheel through a gear 32 and a uni-
~ersal driving shaft 33.
The yoke 25 is suspended at the free end of a guiding linksystem including a guiding link 34 as well as two sepsrate con-
trol links 35 each being composed of two tubes or rods 35, 35',
These control links are connected to plate pieces 36 which are
arranged on a common shaft 37 and pivotable by means of piston-
cylindermechanisms 38.
~3319
On top of the frame 30 there are a number Or limit switches
39 which are placed close to each other, only one of said
switches being visible in Fig. 2. I~ach of these limit 6witches
has a corresponding stop 40 on the plate ~6 (only one of said
stops is visible in E~ig. 2). Said stops 40 has the purpose of
detecting the diameter of the lo~ when the hold0r-on 6 is moved
against the log 2 and,by means of said limit switches 39,actuating
time relays which in turn determine the length of the milling
time. Since the chains 7, 8 and 27 are driven witn a constant
speed the necessary milling time will vary depending on the
size of the logs in such a way that a thicker log will necessi-
tate a longer milling time than a slender log. This is automa-
tically controlled by means of said switches, stops and time
relays.
f course the plate 36 may be provided with other means
for detecting and/or indicating the lowering of the holder-on
6 and thereby the sectional sizes of the logs. Such means might
also be utilized for instance in a marking and/or classifica-
tion system in which the logs are classified depending on their
sectional sizes.
The cutter unit 3 included in the apparatus has the form
of a long cylinder wnich is supported between two spaced apart
supporting arms ~1, 42 directed at angles to the axis of rota-
tion of the cutter unit (see Fig. 1), Said arms ar~ mounted for
rotation about a commo~ shaft 43, By means of piston-cylinder
mechanisms 44 (see Fig. 2) these supporting arms 41, 42 are
pivotally movable from an inoperative position located below
the log to an operative position in contact with the log or
more precicely the buttend of the log overhanging from the
receiving means 4, 50 At the rightward end in Fig. 2 the milling
cutter cylinder 3 is connected to one end of a universal driving
shaft 45 which at its opposite end is coA~nected to a s-tationary
source of power 46, for instance an electric motor. As appears
from Fig. 1 the axis of rotation of said milling cutter cylinder
is substantially parallel to the length of the receiving means
~3;~9
or the apparatus in ita entirety and the cylinder in question
is in practic~ driven in the ~ame direction of rotstion a8 the
direction of rotation of the lo~, that i8 opposite to the dircc-
tion of rotation of the sprocket wheels 9, 10, 1t, 12. ~his i~
the case because the cutting or working element~ of the millin~
cutter cylinder shall work in a direction which is opposite to
the direction at move~ent of the circumferential portions of
ths log.
Now reference i9 made to Figs, 5 and 6 which in detail
illustrate the structure of the milling unit 3. l~s ~ central
part said milling unit comprises a shaft 47 which is mounted
in bearings 48 connected to the supported arms 41, 42 at the
opposite ends thereof, At that end of the shaft which is direc-
ted towards the motor 46 the shaft is rigidly connec"ed to a
member 49 to which the driving shaft 45 is in turn connected,
A lamella or ring 51 is fixed to the shaft 47 by means of
a key 50, said ring being included in a series of rings arranged
side by side along the shaft~ The ring 51 is connected to the
adjacent ring 51' by means of bolts 52. As appears from ~ig, 6
each ring 51 has two diametrically opposed cutting bodies 53,
53' provided in recesses 54 in the circumferential portion of
the lamella ring. Each single cutting body 53 includes two
identical halves 55 and 56 and each of these halves presents
two opposite cutting portions or edge portions 55', 55" and
56', 56" respectively as well as at least one countersink 55"'
and 56"' respectively for a fastening member in the shape of a
headed bolt 57 by means of which the cutting body may be fixed
to the lamella ring, Those portions of the lamella ring which
confine each recess 54 has a convexly rounded supporting surface
~0 58 which has its counter part in the cutting body in two corre-
spondingly rounded concave abuttine surfaces 59, 59',
The ad~rantage of the cutting bodies designed in the above
mentioned way is that they have four ed~es which can be used
as they are worn, because they may be shifted between four
different positions by the adjustment of the cutting bodies~,
When all four edges has been worn the cutting body may be dis-
carded and substituted for a new one,
`` ~L1;~33i9
A~ indicated in Figs. 1 and 2 the various lamella rings
51, 51' etc. are displaced relative to each other in such a way
that the cutting bodies or working elements 53, 53' jointly
form screwshaped configurations along the envelopesurface of
the milling unit.
'rhe apparatus described operates in the following way
when machining a log having root swellings of the type previous-
ly mentioned.
Initially the holder-on 6 is raised to its inoperative
position shown in Figs. 2 and 3. 'rne milline cutter unit 3 is
likewise located in its inoperative position located a certain
distance below an imaginary extension of the Y-shaped channel
constituted by the recesses 14" in the supports 4, 5. Also the
ejecting means 19, 20 are in their inoperative postion (see
~igs. 3 and 4).
A log 2 the swellings 60 of which shall be removed is
rolled onto the receiving means in the form of the supports 4~ 5
from a table (not shown) placed next to said receiving means
so that the log will rest in the V-shaped recesses in the
supportine plates 14 with the chains 7, 8 of both supporting
plates in engagement with the periphery of the log. It should
be noted that the log when being conveyed to the recei~ing
means 4, 5 is located with the buttend freely projecting or
overhanging from the support 5. It should also be noted that
the log 2 often may be of conical shape and when ~ike in the/
log) a ~eneratrix line along the bottom portion of the log
received i~ located in a substantially horizontal plane, i.e.
parallel to the axis of rotation of the milling cutter unit 3.
In the next step the holder-on 6 is lowered towards the log
so that the bottom part 27' of the chain 27 contacts the log
with at least a certain portion of said part being adapted to
the ~ectional shape of the log. 'rhe log is now held in a firm
grip resisting the forces which will be applied to the over
hanging free end of the log by unit 3. ~otation of the log now
held by the holder-o2l6 and the supports is carried out by driving
the sprocket wheel 26" and the shaft 16, meaning that the chains
1~;23319
7, 8 and 27 are moved while rotating the log,
In order to cut off the swellings 60 from the log the
milling cutter unit ~ is pivoted to its operative position in
which it contacts said swellin~swhile at the same time rota-
ting the unit about its axis by means of the motor 46. Inpractice the milling cutter unit 3 i8 rotated at a speed in
the range of 500 to 1 000 RPM, while the log is rotated just
one single revolution. This may be accomplished within 5 to 10
seconds depending on the diameter of the log.
As the milling operation has been finished the milling
cutter unit is lowered to its inoperative position and the
holder-on 6 is removed from the log by means of the piston-
cylinder mechanis~s 38. After that the log is ejected from the
receiving means 4, 5 by means of the ejecting means 19J 20
pre~riously described said ejecting mean~ being pivoted
approximately 90 from the inoperative position to a position
in which they pass a ridge 61 on the ~lates 14, ~hen the log
2 passes this ridge 61 it may automatically roll out from the
apparatus by means of the slantin~ portions 62 of the plates 14.
When the ejecting means have been returned to the inoperative
position the apparatus is ready to receive another log for
machining.
~ rnen assuming its operative position as illustrated in
Fig. 3 the milling cutter unit 3 is located with its center
axis not vertically below the ima~inary center axis of the log
(or the receiver length axis defined by a straight line between
the bottoms of the V-shaped recesses 14" in the plates 14) but
laterally displaced a short distance from the vertical plane
through said log axis. This is the case because in the embodi-
ment shown the milling cutter unit is always moved to a certainfi~ed operative positiont i.e. to one and the same level
irrespcctive of the diameter of the log. If the cylinder were
located exactly below the log axis more useful material would
be cut off from a slender log than from a thicker one since
a slender log would rest deeper in the V-shaped recesses of the
supports than a thicker one. ~y locating the cylinder slightly
~lZ3319
displaced as shown in Fi~. 3 a compromise i9 achieved according
to which substantially no useful wood material will be removed
from slender lo~s. Of course this result would also be achieved
by locating the cylinder vertically under the log axis while at
the same time providing the piston-cylinder mechanisms 44 for
the unit 3 with control means which raises the unit 3 to diffe-
rent levels dependin~ on the diameter of each individual lo~.
An important feature of the apparatus described is the
fact that the log end portion to be machined is freely over-
hanging from a receiving means which supports the log frombelow at the same time as the milling cutter unit used is loca-
ted in such a way that it too contacts the log substantially
from below (i.e. from the same side of the log as the recei-
vin~ means). This means that just the undesired swellings of
the log will be removed while substantially all useful wood
material will be left even if the lo~ is of extreme conical
shape or if the cross sectional shape thereof is irregular.
Of course the apparatus may be utili~ed for machining all types
of lo~s independent of the diameter or cross sectional sizes
thereof.
PQSSIBLE MODIFICATIONS
The invention is not limited meraly to the embodiment
described and illustrated in the drawin~s. Instead of a recei-
vin~ means composed of precisely two spaced apart supports of
the art described it is thus conceivable to use other types
of recei~ing means, for instance receiving means comprising
an appropriate number of wheels and or cylinders. Instead of
just one holder-on two or more such members may be used.
