Note: Descriptions are shown in the official language in which they were submitted.
~¢3~
This invention relates to the sawing
of lumber from logs, and the invention is more
par~ ularly concerned with a method and mearls for
so orienting each of a succession of logs being
fed to a cutting machine that the lumber cut from
each log will be shaped and sized to have the maxi-
~um obtainable economic value, to thus achieve optî~:num
utilization of the ma~erial in th~ log.
.'
In a sawmill in which logs are sawed
in~o boards~ planXs and the like, each log is cut.
by advancing it lengthwise in a horîzon~al feed
dire~-tion throug~ a cutting machine that usually
comprises one or more band saws or frame saws and
may include ~illing cutters or the li~e for trîmming
side surfaces of the log to flatness. Ordinarily,
lades or other cutters in the cutting machine are
..
oriented ver~ically and define a cutting plane that
extend~ horizontally in the feed direc~ion. For
feed through the cu*ting machine, each log is secured
to a feed carriage that is constrained to translator~
~otion in::the feed direction~
It i6 well known that the number ~f
finished pieces that can be cut from a partîcular lvg~
and the ~izes of tha several pieces, ar~ dependent
upon the posîtioning of the log on the *eed carriage
and its orientat;on in relation to the cutting plane.
Heretofore it has been the usual practice to rely
upon a highly skllled operator, working wîth manually
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controlled instrumentalities, to esta~ h each log
on the feed carriage in a position and orien~ation
that would, in his judgment, result in optLmum yield
fro~ the log. To this end the operator usually
rotated the log to a po~ition in which the presumably
best side was uppermost~ ~nd then oriented the log
by swinging its enZssldewardly as he deemed neces-
sary. Whe~ the log was curved along its length~
it was customary ~o ro~ate it to a posi~ion in
which its conve~. side was uppermost, so tha~ it
.: was as nearly as possible symmetrical to the cutting
plane. At best~ however, this could result in no
: . .
~, more than a rough approx~mation of the opti~um
orien~ation of the log because the operator~6
e~timate could give little or no weight to other
~t~: irregularities in the geometry of the log, such as
irregular taper along its length or portions having
markedly flatt~ened, oval or elliptical cross sections~
The problem of:ef~e~ting a truly opti-
mum orientation of every log is an extremely c~mplex ~ ;
one b~cause it depends not only upon the geometry of
each par~icular log but also upon economic factors
that change from time to time. The relati~e economic
value of a given piece of inished lumber has no
nec2ssary relationship to the volume of material that
it contains but depends upon its utility an~ upon
prevailing supply and demand. A given log can often
be cut according to any of two or more different
: cutting patter~ that require different orien~ations
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,
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and positionings of the log and produce different
yields of finished piecesO In such a case, the
optimum cuttin~ patter~ is of course the one that
yields pieces which, together, sell for the maximu~
total price under prevailing market conditio~s.
These many factors had to be con~
sidered by the opera~or, individually and in their
complicated relationship to one ano~her, during the
very ~hor~ ~ime tha~ wa~ available ~or orienting
ea~h o~ a succession of log~ that had to be kept
moving through the sawing machine; and his judgements
had to be ma~e without any of the measurements upon
which accurate results necessarily depended. Ob-
~ viously, even the most highly skillP-d ope~ator could
:~- . not be expe~ted to achieve truly optimum yields w;th
any degree of consistency.
Recent developments in the lumber
industry have lncreased the difficulty of achieving
optimum yields by manual orientation and have at the
same ~lme încreased the urge~cy of ob~aining the
i
optimum yield from every log. Inc~ea~ing demand ~or
~umber in the face o~ a decreasing supply has resulted
in the harvesting of younger and smaller trees and
tree8 of more irregular shape than ~ormerly; and
'. the same supply and demand situation has mada it
imperative that existing lumber resources be conserved
by obtaining optimum yield from every harvested tree.
For some time, therefore, there have been ;ntensive
.
3~i~3
~forts t~ achieve both auto~atic measurement and
automa~ic orien~ation of each log with the use of
automatic measurement apparatus coupled with a
computer tha-t takes aocount of both measurement
data and pertinent econo~ic data~
U.S. Patent No~ 3,459,2~6 discloied
apparatu~ that required an operator to manually turn
each log to ~ ro~a~ional position tha~ he judged
to be favorable for ~awing, and whereby the log was
then scanned by means o~ an arrangement of photocells
that determined its smallest diameter. On the basis
o~ that di~meter measure~e~t, band saw blades by .
which the lo~ was to be cu~ were adjusted latera~ly
in relation to one another to positions that would
result in the presumably optimum cuts. The apparatus
included no means for orienting the log la-terally in the opti-
mum lengthwise relationship to the cutting plane.
Since the only dimension o~ the log that was taken
into:account was its milliMum diameter~ the apparatus
obYi~usl~ opera~ed on the basis of data that was
insufficient: to:ensure optimum yield and in that
respect achieved lit~le or no improve~en-t over the
results obtained with entirely manual adjustments.
The apparatus o~ Patent No. 3,4~9,246
~ad a further de~iciency in being so arranged that
each log was delayed for a time in a zone in which
i~t was rotated and measured, and from that zone the `
log was transported lengthwise to the in-feed ~echan-
sm for the sawing machine~ As a result, there W2S
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a substantial interval of delay from the time when
the sawing of one log ~as completed until the sawing
of the next succeeding log would begin9 and the
apparatus therefore had a relaLively 1Ow production
capacity.
. U.SO Patent No. 37190,323 discloses
:; apparatus whereby, during the sawing of one log,
the next succeeding ~og wa~ rotated to ~n est~mated .
~ optimum posi~ion at a zona that was sp~ced laterally
~rom the in-~ee~ mechaniæm. The rotational~y orien-ted
log was ~ransla~ed laterally to the in-feed mechanism
. .
and ould be clamped to that mechan;sm and started
. ~ , .
through the sawing machine w;th a minimum o delay~
However, the apparatus provided for only rotational
~. orientation of a log and therefore of~ered nv assur-
I ance of optimum yield.
:Methods and æpparatus have also been
proposed whereby measure~ents were taken from which
a calculation .7as mad~ of æ predetermined m~thematical
figure or body ~parallelogram, cylinder or the like)
which could be inscribæd within the surface of an
uncut workpiec.e and which was assumed to be repre-
sentative for the desired scheme o~ cutting. The
centerline of the calculatæd~ theoretically inscribed
~igure or body was determined by à ~urther cal~ula
tion, and the workpiece was adjusted to bring that
centerline into coincidence with the cutting plane.
U.S. Patent No. 3,970,1~8 discloses apparatus of thi~
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63
charac-ter 3 employed for automatic orientation of
cants ~or their pa6sage through an edge trimmer~
Such apparatus was adequate for optimizing the yield
frQm cants and similar essentially two-dimensional
pieces, inasmuch as the assumptions upon which it
operated were valid for such pieces; but with lQgs
and si~ilar essen~ially three-dimensional pieces~ t
merely lateral adj-ustments are insuf~icient to en-
sure that the most profitable cuts will be made.
;
When such apparatus i~ used, for ex~mple, for cutting
a log havi~g sub~tantial lengthwise taper or a
`; markedly non-circular cross-sec~io~, a large amount
, of mæterial i6 wasted from o~e or both sides of the
, - , ~
log, and espeaia1ly ~rom that portion of the length
`: of the log that is nearest ;t~ root end,
~pparatus is also known for measuring
the so-called sweep of a log, that is 9 the departu~e
: of its--actual long.itudinal centerline from true .:
:~ straightness. Again~ such sweep i~ only one o tne
geometrical factors that should be taken into account
in a valid calculation o~ ~he orienta-tion in which
the log mus~ be established if it is to be cut for
: optimum yield. .
It will be e~ident at this point that
the problem of achiev;ng optimum cutting orientation
of a log can only be solved by obtaining ~ very size~
.
able amount of measurement data by which the geometri- ;
cal peculiarities of the log are fully defined. ~7ith
: , .
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35~3
an automatic compu-ter there is no great problem in
maXing the necessary calculations fro~ -the measure~.en-, ..
data, once obtained. But production ef~iciency is
also important. All measuring and calculating on one
log should be accomplished within the time that
preceding log is being sawed, and logs should be fed to ~ ~
the cutting machine in a steady flow, with no substantial ;
delay between successive logs. ~ .
It will be eY iden-t that the
necessary measurements should be made with a minim~n of
manipulation of each log. Furthermore, the measurements
are used for the calculation o a plane that lies in the
!
-~ ~log and moves with it~ and ultimately -the log must be
established in such a ~osition and orientation that that
~ .
calculated plane is parallel to the cutting plane and at
a predetermined distance from it, hence, from the beginning
of the measurement~process, all movement of the log must
be~accurately controlled in order to ensure that the cuttlng
of the log will actually take place in exact accordance
with calculations. The importance of accuracy in measuring
the log and positioning it on the feed mechanism is apparent
from the fact that an improvement in cuttîng accuracy of
as little as 2 mm. can increase profitability ~y about 2%.
::
In many cases accurate measurement and positioning of a
log can enable a useful board to be sawed off of a side
portion of it that would otherwise be reduced -to chips~
The general ob~ect of th~ present
invention is to provide a~method and apparatus whereby
all necessary mea~urements can be made on a log or
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~3356;3
similar workpiece of possibly irre~ular shape to enable
calculations to be made from which a position and
orientation of the workpiece can be established that
will afford an optimum yield of finished material, and
wherein such measurement and orientation are accomplished
' in a manner that enables logs to be processed in rapid
succession~ so that a high rate of production is
achieved along with optintum yield.
More specifically, it is an object
~ o~ the invention to provide a method and means for
taking meastlrements on a log or the like, whereby
the geometrical features of the log that are essential
. .
to optimum cutting are fully and accura-tely ascertained,
to enable optimum yield from the log to be calculated
by means of a compu-ter; whereby all movements of the `~
1 .
log are fully and accurately controlled ~from the time
when measurement begins until sawing of the log is
completed, to ensure that the calculated optimum yield
will actually be obtained.
,
It is also an objec-t of the invention
to provide a method and means for automatically
ob-taining measurements that define all of the geometrical `
features of a three dimensional workpiece tha-t must be
taken into account for sawing the workpiece to obtain
` optimum yield from it, and whereby such measurements
can be made with a minimum of movements of the log and in ',
less time than is required for the actual sawing of the
workpiece.
Another object of the invention is to
provide a method and means ror measuring and or~enting ]ogs
., , . . . ~
~3~ii3
or similar workpieces to obtain optimum yield from each work-
piece, whereby workpieces can flow in a substantially uninter-
rupted succession throuyh a cutting or sawing machine, without
delays for accomplishing measurement and orientation, to thereby .
achieve a high production capacity.
With these observations and objectives in mind, :
the manner in which the invention achieves its purpose will be
appreciated from the following descri~tion and the accompanying
drawings, which exemplify the invention, it being understood that
~; 10 changes may be made in the precise method of practicing the
invention and in the speciic appaxatus disclosed herein with-
out departing from the essentials of the invention set *orth in
the appended claims~
The accompanying drawings illustrate one complete
example of an embodiment of the invention constructed according
to the best mode 50 far devised for the practical application of
: the principles thereof, and:in which:
FIG. 1 is an end view of log processing apparatus
embodying the principles of the present invention; .
FIG. 2 is a view in side elevatlon of that portion
of the log processing apparatus that comprises the sawing machine
and the feed mechanism by which a log is fed into the sawing
machine;
.
: FIG. 3 is a top view of the log processing apparatus
shown in FIG. l;
FIG. 4 is a somewhat simplified plan view of the
transfer mechanism in its relation to the feed station;
FIG. 5 is a view generally similar to FIG. 3, but
on a larger scale and showing only a portion of the feed mechanism;
FIG. 6 is a diagrammatic view .illustrating measure-
ments taken during scanning of a log at the measuring station;
FIG. 7 is a diagrammatic representation of the math-
ematical model of a log derived from data obtained by scanning; and
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35~
FIGS. 8a-8d are diagrammatic views illustrating,
in sequence, the successlve steps in the processing of a
log according to the method of this invention.
`` GE:NER~ AR~JGEMENT
j Referring now to the accompanying drawings, and
first referring par-ticularly to FIGS. 1, 2 and 3, apparatus
embodying the present invention comprises a sawing or cutting
machine designated generally by 5 through which logs L are
`` fed one-by-one by means of a feed mechanism designated
; 10 generally by 7~ It wlll be understood that the workpieces
herein characterized as logs could be other log-like articles,
as for example blocks, i.e., lumber pieces having two planar
.~' - -
; parallel surfaces but otherwise rough and irregular. As will
appear as the description proceeds, each log is supported
by the feed mechanism 7 in an orientation and lateral
position which is distinctive to the particular log and
which will result in an optimum yield from it. For the
!: ~ purpose af obtaining measurement data about each log,
from which its optimum roientation in the feed mechanism ~ ;
7 can be calculated,~ logs~ destined to pass through the
cutting machine 5 are first delivered one-by-one to a
~measuring station 8. From the measuring station, each log
: i5 carried to the feed mechanism 7 by means oE a transfer
mechanism designated generally by 9. The apparatus is so
arranged that while one log L3 is being fed through the
cutting machine 5 by the feed mechanism 7, a second log L2
is in transit from the measuring station 8 to the feed
mechanism on the transfer mechanism 9, and a third log Ll
is being processed at the measuring station.
The sawing or cutting machine 5 can be of '~
any suitable type~ It is here illustrated as a reducer
saw comprising cutters 10 in the nature of milling cutters,
... ...
~ ~ ~3~;~3
by which ma-terial is removed from opposi-te sides of a log
to bring its sides to flatness and parallelism, and one
or more saw bands 11 past which the log moves immediately
after being acted upon by -the cutters 10 and ~1hich can
saw the log lengthwise into two or more pieces. As
shown, the cu-tting elements 10, 11 of the cutting machine
are disposed to define a vertical cutting plane S -that
extends horizontally in a feed direc-tion along which
logs are carried in tr~nslatory more or less lengthwise
motion by -the feed mechanism 7. However, it will be
unders-tood that the cutting elements 10, 11 of the cutting
machine could be so orien-ted that the cutting plane S
is inclined to the ver-tical. The cutting plane S may be
a plane on which a central longitudinal cut through the log
is to be made, or may be a plane on which one of a plurality
oP parallel longitudinal cuts are to be ~ade, or may be a
plane on which no actual cut is made but to which all cuts
are to be parallel; hence the cutting plane may be regarded
as any single plane through the cutting machine, parallel
-to the cut or cuts made by tha~ machine~ and from which
said cut or cuts have a prede-termined spacing which may be
zero.
The cutting machine can also comprise
a planer 12 WhiC}I is located some distance ahead of the
i vertical cutting elements 10, 11 and which trims at
least portions of the bottom surface of a log to fla-tness
before the log is engaged by the vertical cuttîng elements.
Between the planer 12 and the vertical cutting elements
there is a belt conveyor 13 having a flat, horizontal
upper stretch lying in the cutting plane of the planer 12,
After a log has moved across the planer, a hold-down
- 12 -
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,
roller 14 bears downwardly upon it to maintain i-ts flat
bo-ttom surface portions firmly engaged agains-t the conveyor
13, wher~by it is guided into engagement with feed rolls
15 which~ in turn, guidingly feed it to the vertical cu~ting
elements 10, 11. The conveyor 13 and feed rolls 15 ean thus
take over guidance and feeding transport of a log after
it has been released by the feed mechanism 7.
MEASU~ING STATION
The measuring stàtion ~ is spaced a
distance to one side of the cutting plane S.~ Logs
L are brought to the measuring station one-by-one
by means of a chain conveyor 17 on which -they are transported
: transversely to their lengths. In moving to and through
the measuring station the logs have more or less the same
orientation that they will have as they are advanced
through the cutting machine 5, that i5 ~ each log has its
length substantially horiæontal and more or less parallel
to the cutti.ng plAne S. As shown, all of the logs have
their narrower upper ends towards the sawing machine, and
for simplicity it is ass:umed in the following description
that they are so oriented, although ;t is not necessary
that they be so oriented~ Pre:Ferably, before reaching
the measuring station~ all of the logs are so aligned,
in a known manner, that their upper end surfaces lie in
a common vertical plane 18 that is normal to the cutting
plane.
The measuring station 8 defines a measuring
zone extending to opposit~ sides of a reference plane Ml
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13 - j
3~i6~
that is in a known, fixed rela-tion to the cutting plane
S (e.g., parallel to the eutting plane) ana is spaced
a substantial disLance to one side of it. Mechanically 3
the measuring station comprises a pluralîty of log
suppor-ts 21a-~ld that are arranged in a horizontally
extending row. Each log support comprises a pair of
chain arms 22, 23 that are swingable up and down~ to and
from an operative position shown in FIG. 1, about a
horizontal axis that lies in the reerence plane Ml.
In the ope~ative position of a log support, its two
chain arms 22, 23 extend obliquely upwardly and laterally
away from one another to define a V in which a log can
be cradled. In the inoperative position, both arms are
horizontal.
. Every log is supported in the measuring ~ :
zone by only two of the log supports, one of them being
the front support 21a~ which is located near the
transverse plane 18 and which supports the log near its
top end, and the other being whichever one of the other
three supports 21b-21d is inwardly nearest the root
end of the log. The particular one of the three
supports 21b-~ld that is to cooperate with a particular
log can be selected either manually or by means o:F
automatic apparatus tnot shown~ that can comprise a
i.. ,!sensor which detects the length of each log as it enters .
the measuring zone. The two supports not needed at any
given t:ume remain in their inoperative horizontal
positions, in which they are out of the way of logs
entering and leaving the measuring zone. I -~
- . ,
- 14 ~ ~
... .. .
By means of the operative pair.of suppor-ts
21a and 21b, 21c or 21d, a log at the measuring s-tation
is supported in such a manner as to be rotatable but
to be substantially confined against other movements.
To provide for rotation of the supported log, each o~
the log suppor-t chain arms 22, 23 comprises an endless
chain 24 trained around sprockets 25 at opposite ends
of the arm and having a straight stretch extending
along the side of the arm against which a log engages~
A log can be rotated by driving the sprocket~ 2~ in unison~
all in ~he same direction. The amount o~ rotational
displacement imparted to the log can be measured by
means of an ~ngle sensor 26 located near the transverse 1
plane 18 and rotatable about a horizontal axis lying
:~ in the log. As shown, the angle sensor aomprîses a
. pair of claws 27 which are swingable towards and from
one another to grip opposite sides of the-log near its ~¦
top end. It will be understood that the log could be
rotated by means of a suitable rotary actuator coupled
to the claw mechanism 27, and in that case the sprockets
25 would be freely rotatable so tha~ the chains 24 on
the chain arms would not interfere with rota-tion of the log.
Each of the log supports has a double
acting cylinder motor 28 by which its chain arms 22, 23
are swung up to their operative positions and down to
their inopera-tiYe positions. The ~inkage by which
each motor 28 is connected with its chain arms is of
a known type and is therefore not shown in detail. The
motors 28 are connected in a hydFaulic circuit 120
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~ 3~
that can comprise a:pressure fluid pump P and a valve
128 for each motor 28. Each of the valves 128 ~an be
controlled either manually or (preferably) automatically
in a manner that will be evident ~rom the functions
performed by the chain arms.
The measurements that are made at the `
measuring station 8 provide information about the
log from which a mathematical model 29 (see FIG. 7)
can be produced that defines the geometry of the log
in a somewhat simplified form. From this model
calculations cah be made that define the optimum
orientation of the log for cutting. While any such
mathematical model mus-t necessarily be based upon certain
simplifying assumptions, the assumptions that are made
in this case do not result in a model which is materially
~''' ' .
inaccurate.
By the method of this invention, a
number of surface stations 30 are defined for the log,
spaced at intervals along its length, and at each such
surface station measurements are made that enable a
polygon to be calculated that circumscribes the log at
that station. All such calculated polygons have the
same number of sides (e.g., all are octagons), but
they are not necessarily regular, and obviously they vary
in si~e as ~ell as in shape from station to station.
- Corresponding angles of adjacent polygons are then
connected by straight lines to produce a model 29 of
the log such as is illustrated in FIG. 7.
I
- 16 -
3~3
This measurement me-thod will be more
Eully understood from the following explanation of how
the necessary measurements are made automatically by
means of the apparatus illustrated in FIG. 1, which
comprises a pair of array cameras 32, 33. An array
camera comprises a row of photoelectric cells which are
scanned or "emptied'l electronically with the use of a
pulse signal. The field of view 13~ ~see FIG. 8aj of
an array camera is a straight~ narrow sweep, the ends
o~ which define, with the camera, a scanning angle
at the camera that is bisected by an optical axis of the
camera~
/ The array camera 32 i9 mounted a
substantial distance above the log supports 21a-21d
.~ and is so oriented that its optical axis is contained in
the reference plan Ml and its scanning direction is
transverse to that plane. It thus scans across the
~ width o~ a log at the measuring station. Furthermore
(although not shown in the drawings)~ -the appara-tus
at the scannîng station includes means by which the
field of scan 132 of the array camera 32 is advanced
lengthwise along the Scannlng zone *rom scanning
sweep to scanning sweep, in such a manner that each
scanning sweep crosses the log at one of the surface
stations 30 . Movement of the scanning field 132 from
surface station -to surface station can be accomplished
by bodily translatory movement of the array camera
along the reference plane ~1 or, as preferred, by means
of a swinging mirror arrangement such as is fully
,
5~
disclosed in U.S. patents No. 3,886~372 and No. 3,963,938.
The array camera 33 is arranged similarly
to the array camera 32, but its op-tical axis lies in a
measuring plane M2 which is inclined at a suitable angle
(e.g., 45) to the reference plane Ml and which intersects
the reference plane Ml along a horizontal line that lies
in the log. The field of s~an of the array camera 33
is likewise caused to move along the length of the log
from scan to scan, so that each of its scanning sweeps
is made at one of the surface stations.
A first scanning of the log at -the measuring
station takes place with the log in whatever rotational
:
position it has upon arrival theren A-t each surface station
along the log (see FI~. 6), the array c~nera 32 measures
; the angle at the camera between the reference plane Ml
and each of the llnes that extends from the camera and is
tangent to the surface of the log~ and at the same surface
station the array camera 33 similarly measures angles at
the camera between the reference pIane M2 and lines from
the camera that are tangent to the surface of the log.
These measurement values, each of which corresponds to
a trigonometric function of angle of scanning sweep in
relation~to the optical axis of +he array camera, are in
the form of electrical ~ignals that are fed to a computer
(not shown), preferably a suiiably programmed general
purpose computer.
; ,.
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~3S~63
Upon the basis of the two sets of
measurements just deseribed, a quadrangle can be derined
th~t circumscribes the log at the surface station.
Now the log is rotated at the measuring ~`
station, preferably through 90 , and is seanned again
in the same ~anIler' to obtain information from which
another quadrangle ean be de~ined at each surface
s-tation. Each side of each quadrangle intersects two
sides of the other to define an octagon that
circumscribes the log at the surface station. Since
the log rests on its surface as it is being rotated, the
irregularities of its sur~ace cause it to undergo a
certain amount of uncontrolled shifting in directîons
transverse to its length, and therefore the two
~, quadrangles calculated for each surface station cannot
be directly superimposed upon each other to obtain the
- ~circumscribing oc-tagon. This means that the set o~
quadrangles (one or each surface station) derived from !`~
the first set of measurements must be mathematically
shi~ted. Since the actual distance and direction of their
individual shifts is unknown, but the shifting of each
is related to the shifting of all of the others, the
cri~erion employed for controlling the mathematical
shifting of those quadrangles is that they be so shifted
that the to-tal area of the octagons at the several surface
stations îs a maximum.
Instead of two array cameras, three
array cameras could be used, the axis of one camera
being in the reference plane Ml and the other two
:
." ' ` ~
19
~ ?35~3
cameras having -their axes in measuring planes at
opposite 60 angles to the reference plane. The
three c~meras ~Jould make their scans simultaneously,
and the data obtained from them would be used to
define a hexagon at each surface station along -the
log. Although such a three-camera system would avoid
the need for rotating the log and would subs-tan-tially
shorten scanning time, it would require more equipmen-t
and substantially more lateral space at the scanning
station, and the illustrated two camera arrangement
is there~ore pref~rred.
$he computer that receives outpu-ts from
the array cameras 32, 33 calculates a prism 29 which is
defined by straight lines connecting corresponding angles
; of polygons at adjacent surface stations and which serves
as a mathematical model of the log.
Certain parameters are storea in the
memory of -the computer that relate to available cu-tting
~ .
patterns, prevailing prices and the like; and on the
~20 b~asis of those parameters and the prismic model derived
from the scan or scans, the computer calculates a
theoretical plane K which lies in the log and moves with
i-t and which should be established in a predetermined
relationship to the cu-tting plane S for sawing of the
log, in order to obtain optimum yield. It will be
understood that the calculated plane K could in fact
comprise plural parallel planes, along each of which the
log is to be cut; hence the calculated plane K can be
regarded as any single plane in the log which, for
op-timum yield, should be parallel to the cutting plane
- 20 -
5~3
S during cuttin~, and should also then be at a pr~de-termined
dlstance ~rom the cutting plane~ which distance may be zero.
Tne loca-tion of the plane K is es-tablished in r21a~ion to a
three-axis coordina.e system related to the reference pl~ne
Ml, to the transverse plane 18, and to a third plane that is
mutuzlly perpendicul~r to those two planes and is in a pre-
determined r21ationship to -the plane of the upper stre-tches
o~ the belt conveyor 13.
At the measurina station, thP log is rotaLed
~O to a position at which any line that extends transversely to
the log and is con~alned in the calculated plane X îs parallel
- to the cut~ing plane S. Thus, assumlng tha~ the cu~ting plane
S is vertical and that the reference plane Ml is likewise
ver~ al and parallel to the cutting plane, the log is rotzted
to bring the calculate~ plane K to a vertical orientation~ Of
,! ~ course~ wi~h that orienta~ion, the ca~culated plane K will no~
! necessarily be parallel to the reference plane Ml but will
most likely be at a d;stance from it that varies along ~he
; length of the log, as denoted by ~ Xt and A x~ in FIG. 8c.
Once the log is established in that optimum
rota-tional orientation, it is maintained in.~hat ro-ational
orientation until it has passed through ~the cutting machine 5.
More acurately, all ~urther movements of the log are e~fected
in such a manner -that: if the reference plane Ml is parallel
to the cuttin~ plane S, further rotation of the-log is prevented;
and if the reference plane is non-parallel to the cutting plzne,
the log is confined to controlled rotation such -that i~ arri~es
- a-t the ~eed mechanism with its calculated plane K in the sa~e
relation to -the cutting plane S th~t it had to the reference
30 plane Ml at the measuring station.
-- 21 --
When the log is establis}-ed in the desired
ro~ational position at the measuring station, it is
transferred to the grip of the transfer mechanism,
as explained below and as depicted by FIGS. 8b and 8c.
~ith the particular transfer mechanism -that is herein
described, some lateral shifting of the log may take place
as a result of transfer of its support to the transfer ::
mechanism from the log supports 21a-21d of the measuring
s.ation, and therefore, after such transfer oE support has
~ccured, but ~efore the log moves away from the measuring
station, the lo~ i5 once again scanned as depicted by FIGn 8c~
to obtain an exact measurement of the relationship between
the calculated plane:K and the reference plane Ml. The
in*ormation obtained from that scanning is subsequently used
to so control lateral movements o~ the log as to bring its
calculated plane K into the desired relationship to the cutting
r
r plane S.
. ~ :
It will be evident that the equipment can be
somewhat simplified, and that a much less complicated program
2~ is needed for the computer that makes calculations from the
:measurement data obtained from scanning, if a semi-automatic
,~ . .
procedure is used at the measuring s-tation instead of -the
fully automatic procedure defined above. For that semi-
:~ automatic procedure, an operator. manually controls rotation-
of the log to bring it to a rotational orientation that he
estimates to be optimum for sawing. The log is transferred
to the grip of the transfer mechanism and is then scanned,
: as illustrated in FIG. 8c, to obtain measurements from which
: a calculated plane K in the log can be determined and its
relationship to the reference plane Ml ~and hence to the
cutting plane S~ can be ascertained.
- 22 - .
. . ... .
~1~3~63
TRANSFER MECHANISM
.
The -transfer mechanism 9 by which a
log is moved from the measuring station 8 to the feed
mechanism 7 com~rises a carr;age 35 ~Tnich is elongated
in the feed direction and which is guided for horizontal
motion transverse to its length by means of f;xed
parallel rails 36. Upper and lower rollers 37 and 38
on the carriage 35 engage the top and bottom surfaces
: o the.rails 36 to con~ine the carriage to translatory
motion along the rails. Such motion can be imparted
~ 10 to the carriage by means of a double~acting cylinder
motor 39 which reacta between the carriage 35 and a
stationary part of the machine frame and which is
connected w;th a valve 139 in the hydraulic system
120 to be contr.olled manually or (pre~erably)
automatically in a manner which will be evident from
the ~unctions that it performs.
The log to be transferred is secured
to the carriage 35 by;means of pairs of gripper jaws 41,
~ : so located along -the length of the carriage that each ` :
~ 20 ~ pair of gripper jaws is spaced a s~all distance along
the leng-th of the carriage from one of the log supports
21a-21d of the measuring station, so that each of those .
log supports has its corresponding pair of gripper jaws , ~
: 41. To permit the gripper jaw pairs 41 to be individually i `
raised and lowered relative to the carriage, each pair of
gripper jaws is mounted on an elevator frame 42. Each
I ~ elevator frame 42 is constrained to move with the ,.
carriage and is guided for up and down motion relative
to the carriàge ~y means of upright guide posts 43 that are '
.
- 23 - . I
3~-~;3
I ixed to the carriage and are engaged by sui-table guide
rollers on the elevator frame. Each eleva*or frame 42
is raised and lowered by means OL its o~m cylinder rnotor
44, which reacts be.ween the elevator frame and the
carriages and each motor 44 is connected with its own
control valve 144 in the hydraulic circuit 120.
Each of the gripper jaws 41 comprises
a lever-like jaw member that is pivoted to the elevator
~rame ~or the jaw pair. The two jaws of each pair are
respectively swingable abou~ parallel horizontal axes
defined by shafts 45, to which -the jaw members are
rigidly secured. Also rigidly secured to each shaft
45 is a lever arm 46 that projects away from the jaw
member. Connected between the free ends of the lever
~; arms 46 is a double-acting cylinder motor 47 which
diverges the jaw members 41 when it contracts and
converges them when it extends. Each cylinder motor 47
is controlled by its own valve 147 in the hydraulic
circuit 120. To coordinate the swinging movements of
the two jaw members 41 of each pair, so tha-t they swing
symmetrically to a vertical plcme midway between their
axes, a suitable linkage 48 is connected between their
sha~ts 45.
When the cylinder motor 47 for a pair of
jaw members 41 is fully contracted, those two jaw members
are in nearly horizontal attitudes, so that they can pass
under a log that is supported in the operative log
supports 21 at the measuring station. Furthermore, when
I
the carriage 35 is moved to the measuring station by
. .
- 24 - I
extension of the cylinder motor 39~ each of the
eleva-tors 42 is in its lowermost position, to ensure
that -the open jaws will be spaeed beneath the log as they
pass under it. Two of the elevators can then be raised,
: by means of their respective cylinder motors 44, until ~ ~;
they just engage the underside of the log, and thereupon
the pairs OI gripper jaws 41 on those elevators can be
swung shut, to engage a~ainst opposite sides of the log,
by extension of Lheir cylinder mo-tors 47. The pairs o~
gripper jaws 41 that enga8e the log are of sourse those
that correspond to the log supports 21a-21d then engaging
it. Once -the log is thus securely held by the transfer
mechanism, the chain anns 22, 23 at the measuring station are
swung down to their horizontal positions, to be clear
of the log as it is carried out of the measuring s-tation
and towards the feed mechani~sm 7 upon contraction of the
~"' . , .
cylinder motor 39 for the carriage 35. As the log is
carried towards the~feed mechanism, a new log can be delivered
; to the measuring station.
: .
As explained above, transferring support
of the log from the V-shaped chain arms 22, 23 to the iaws
41 may cause some lateral displacement of -the log~ because
the jaws 41 do not~engage the same portions o its surface
as the chain arms 22, 23, and therefore a scanning takes
place aEter the log is in the grip of the ~aws 41 but
before it leaves the measuring station. Sinee the ~ransfer
mechanism carries the log to the feed mechanism withou-t
rotation, through a predetermined distance, and with a ~ ¦~
lateral motion that is accurately known ~inasmuch as it is
purely translatory), the log will arrive~at the ~eed -
'~ .
.- ~.
- 25 - I
mechanism with its calculated plane K in exactly a known
relationship to the cutting plane S..
During la-teral transport of the log from
the measuring station -to -the feed mechanism, or immediately
upon the conclusion of that lateral transport, the
elevator motors 44 for the -two pairs of jaws 41 that grip
the log are operated to lift the log to a vertîcal position
and orientation in whi~h i- is to pass through the cutting
machine and in which a desired trimming cut will be made
.
by the planer 12. With the log in that.position~and
orientationj it is gripped by the feed mechanism in such
~: a manner (as explained hereinafter) that no movement of
the log takes place during its transfer from support by
the transfér mechanism to support by t~e fe2d mechanism.
. pEED MECHANISM
The feed mechanism 7 to which the log
is: delivered by:the transfer~mechanism 9 comprises
an inner feed carriage 50 and an outer feed carriage
51~ both of which move along tracks provided by a
~ paîr of parallel I-beams.52 that are supported on
;~ 20 suitable uprights 53 a~ an elevation some distance
::
: above the top of the cutting machine 5. These -beams
extend horizontally in the feed direction and have I ;
their front end portions over the cutting machine 5.
Each I~beam has inner flanges 54 that project laterally
~~ ~ towards the other I-beam, and these inner flanges
of the two I-beams cooperate to provide the rails of an
inner track upon which the inner ~eed carriage 50 is
supported and ~uided. The opposite or outer flanges 55
on the I-beams, which proiect away ~rom one ano-her, define
30 : the rails of an outer track upon which the outer feed
- 26 -
6~ ~
carriage 51 is supported and guided.
The inner feed carriage 50 lies wholly
between the rails of the inner track. The outer feed
carriage Sl, however, straddles or bridges across both
sets of tracks and engages the rails of the outer racX
at their outer or remote sid~.s. It will be apparent,
therefore, that the carriages 50 and 51 can pass each
other freely as they move in either direction along the ~
tracks. '
Each of the feed carriages is equipped with
a pair o~ pincers-like gripping jaws~ the jaws on the
inner carriage 50 being designated 56 and those on the
outer ca,rriage 51 being designated 57. These pincers-like
jaw elements on each carriage projec-t obliquely downwardly
and forwardly from the carr;age, so that they can
cooperate to support a log at an elevation suitable
:
for its feed to the sawing machine. The jaw elements
are thus at the level of a feed line along which the log ~,
moves in its feeding motion. In each case the jaw ele~ents
56, 51 on a carriage 50, 51 are swingable toward and ~rom
one another about a vertical axis. As the description
proceeds, it will be apparent that the structure which
supports and controls the jaw ele~ents 56 on the inner
carriage SO is located wholly between the inner rails,
whereas the structure that supports and controls the Jaw
elements 57 on the outer carriage,51 is located above
the inner tracks and laterally outside the outer tracks;
and this arrangement, too, is for the purpose of enabling
the carriages 50 and Sl to pass one another.
;
- 27 - ;'
11~3563
It will noW be apparent tha-t wi-th the feed
carriages SD and 51 occupying s-tarting positions along the
tracks, such as their positions shown in FIG. 3, the
carriage 35 of the transfer mechanism can be brought to
a posi-tion in which a log thereon is more or less centered
between the I-beams 52 that provide thé feed mechanism tracks;
and with the log vertically posi-tion~ at the level of the
feed line 3 as explained above, it can be gripped by the
jaw elements 56 and 57 on the respective feed carriages
S0 and 51. Thereupon, the gripper jaws 41 of the transfer
mechanism can be swung apart and downwardly by contraction
of their cylinder motors 47, and the carriage 35 of the
transfer mechanism can be returned to the measuring station
8 for another log.
' ' `
As the explanati~n proceeds, it will be
seen that when the pincers-like jaw elements'56, 57 on the
S , two feed carriages 50, 51 are converged to grip a log
.
supported by the transfer mechanism, they adjust themselves
laterally, to securely clamp the log without shifting it;
~and thereafter they can be,swung laterally, with the
~i .
clamped lo~, to establish the log in the desired lateral
position and orientation. For an understanding of how this is
accomplished, attention must now be given to details of
,the two carriages 50, 51 of the feed mechanism.
The outer carriage 51 comprises a
rectangular horizontal frame 59 that is wide enough
to span the I-beams 52 and is supported at an elevation
well above the I-beams on legs 60 that projec, down
from its four corners. The two legs 60 at each side
of the carriage have their lower ends connected by ,
a short bea~ 61 tha-t lies laterally outwardly of the
- 28 -
3~ 3
ou~er I-beam flanges 55 and on whieh are mounted
freely rotatable rollers 62 tha-t engage the flanges
55 to supportingly guide the carriage. At each side
of the carriage the frame 59 and the beam 61 conjointly
- support and journal an upright shaft 64 that is confined
to rotation. Note that each of the shafts 54 is located
laterall~ ou.wardly of the outer flanges 55 of its adjacent
l-beam, and that the lower end portion of each shaft is
at a level below the ~-beams. To the lower en~ of each
of the shafts 64 is anchored one of the arms 65 that
comprise the pincers l;ke gripping element 57 on the
carriage 51. By simultaneous ro~ation of the shafts 6
in opposite directions, the two arms 65 can be swung
towards or,away from one another. Such ro-tation is
imparted to the shafts 64 by means of a lever arm 66 fixed
to the upper end of each of the shafts 64 and a double-
P'`'
~- acting cylinder motor 67 that is connected between the
~free outer ends of those two lever arms. The lever
arm 56 on each shaft 54 projects la-terally from that
shaft in the same direction as its associated jaw arm
65, and therefore con-traction of the cylinder motor
67 converges the jaws and its expansion diverges the~.
Through a control valve 167 the jaw actuating cylinder
motor is connected in a hydraulic circuit with a pump P2
that provides a source of pressure fluid.
For shifting the lateral position of
the converged jaw elements 57, each of the shafts 6
has a fur-ther la-terally pro~ecting lever arm 70, 71
secured to its upper end, the lever arm 70 on one
shaf~t being oriented more or less forwardly while
I
"
,
- 29 -
the lever arm 71 on the o-~her shaft is oriented more
or less rear~lardly. Connected ~e-tween the outer
ends of these lever arms 70 and 71, and comprising
an adjustable-length link be~ween them, is another
double-acting cylinder motor 72. The cylinder motor
72 is controlled by means of a four-condition control
valve 172 which is connected in the hydraulic circuit
comprising the pump P2. The control valve 172 has a
"float" condition in which the motor 72 is cut afr from
the pump P2 and fluid can flow freely between opposite
ends of its cylinder s~ that the motor can readily
extend or con-tract in response to forces exerted upon it
by the lever arms 70 and 71. In a "locked" condition
of the valye 172~ in which the motor 72 is also cut
off from the pump P2, fluid is prevented from *lowing
to and from that motor 50 that it is confined against
extension and contraction. In the other two conditions
:
of the valve 172 it communicates the motor 72 with
the pump P2~ and in one of those conditions it causes
the motor to extend, while in the other it eauses the
motor to contrac-t. A sensor 73 is connected between the
cylinder and -the piston rod of the motor 72 to produce
an output which corresponds to the preYailing length of
the adjustable-length link tha-t comprises the mo-tor 72.
;- When the jaws 67 are converged -to grip
a log that is being supported by the transfer mechanism
9, the cylinder motor 72 is allowed to float~ so
that the ~aw arms 65 can swing as necessary to adapt
themselves to the position of the log. Once engaged
with the log and confined in engagement with it by
the converging force exerted upon them by the cylinder
'
- 30 - .
- ~ .: . ~ ...
5~3
motor 67, the distance between the free ends of the
arms 65 is fixed, and it will be apparen-t tha-t con-traction
of the cylinder motor 72 causes the free ends of those
.
arms (together with the portion of the log that is
between them) to be shifted in one lateral direction
tdown-~ard in FIG. 3), whereas extension of that motor
effects an opposite.lateral shift of the arms 65 and the :~
log between them~ The sensor 73 produces signals that .
correspond to -the direction and magnitude of such lateral
shifting, and by means of suitable control circuitry
~not shown) to which those signals are fed and which
also receives com~uter outputs signifying the relationship
between the calculated plane K in the log and the cutting
plane S, the lateral position of the jaw arms 65 is
established at the calculated optimum lateral position
of the log, With the jaws 65 so positioned, the motor 72
can be put in its,"locked" condition to hold the jaws
against lateral:shi.fting. - ,
The cylinder motors 67 and 72 on the
outer feed carriage 51, and the lever arms with w~ich
they respectively connect, are all located at a level
substantially above the I-beams 52, so that no inter-
ference is presented to the inner feed carriage S0
when the carriages 50 and 51 pass one another.
The gripping elements S6 on the inner
feed carriage 50 are actuated and positioned by
.
mechanism which is in most respects similar to the
above-descri.bed mechanism on the outer carriage 51
but, in addition, the lever arms 75 that comprise
i those gripping elements are capable of being swung
~;
'
- 31
~3~63
upwardly, to an inoperative posi-tion shown in broken
lines in PIG. 2 and in which they are at a level
just below the bottom surfaces of the I-beams 52. In
this inoperative position they can readily pass between
the upper port1'ons of the jaw arms 65 of the outer
feed carriage 51.
The inner carriage 50 comprises a
horizontal rectangular frame 76 having lengthwise
extending side members 77 on which there are rollers
78 that engage the inner flanges 54 of -the I-b ams,
to movably support the frame. The side members also
provide bearin~s for a cross-beam 79 that extends
between them and is rotatable about a horizontal axis
which extends lengthwise in it and which is thus
transverse to the feed direc-tion. Shafts 80 that
correspond generally to the sha~ts 64 on the outer
carriage are journaled in the rotatable cross-beam
79 and have the jaw arms 75 secured to their lower
ends, so that rotation of the cross-beam 79 abou-t its
axis raises those jaw arms to their inopera-tive
position or lowers them to the operative position shown
in full lines in ~IG. 2. Such swinging motion is
imparted to the rotatable cross-beam 79 by means of
a double-acting cylinder motor 81 which has one of
its ends connec-ted to one of the end members of the
frame 76 and its other end eccentrically connected
to ~the rotatable cross-beam. The cylinder mo-tor 81
is connected with a control valve 181 that is in a circui-t
with a pump P3.
The jaw arms 75 on the inner feed carriage
.
. ' - ,
- 32 - ;
. ... .
3~
are converged and diverged by means of a double-acting
cylinder motor 83, corresponding to the cylinder mo-tor 67
on -the ou~er carriage and connected between lever arms 84
fixed to the upper ends of the shafts 80. The motor 83
is controlled by means of a valve 183 ln circuit with the
pump P3.
The inner carriage has a lateral-jaw
shifting arrangement which is essentially like the
one on the outer carriage, coJnprising forwardly and
I lO rearwardly projecting lever arms 86 and 87, secured :~
to the upper ends of the respective shafts 80, and
: a double-acting cylinder motor 88 connected between
the ends of the arms 86 and 87. A valve l88 for
controlling the motor 88, connected in circui-t with
the pump P3, again provides for "float" and "lock"
as well as for contraction and extension of that motor;
,
: and a sensor 89 is arranged to produce signals
corresponding to the direction and magnitude of lateral
shifting of the lever arms 75.
As pointed out above, the log arrives
at the feed mechanism with its calculated plane K
in a known relations~ip to the cu-tting plarle S, as denoted
by the distances~ Xl and~ X" în FIG. 8d, and the lateral
shifting -that is imparted to the gripping elements
56 and 57 on the feed carriages is such as to establish
the log with that calculated plane parallel to the cutting
plane S and at a predetermined distance from it. Said
distance may be zero, that is~ the planes K and S may in
some cases be required to coincide. Such lateral shifting
is of course effected under the control of -the computer
:~ '
- 33 - 1
" ~, . , - ~
S~3
(not shown) in cooperation with the sensors 73 and 89.
The carriages 50 and 51 are moved
along their tracks in feed and return directions by
means of reversible electric motors 90 and 91,
respectively, that are supported on the rear end
portions of the I-beams 52. The motor 90 drives inner
feed carriage 50 through a rPducing gear box 92 and a
rotatable horizontal drive shaft 93 that ex-tends transversely
to the feed direction and i9 rotatably driven from the
0 gear box 92 by means of a chain drive transmistion
generally designated 9~. Secured to the oppos;te ends ;
of the drive shaft 93 are drive sprockets 95 that overlie the
inwardly projecting flanges 54 of the I-beams. A freely
rotatable sprocket g6 is mounted over the front end of
each of the I-beams, in line with each of ~the drive
sprockets 95 on the drive shaft 93. Over the driving
and driven sprockets 95, 96 at each side o~ the feed
mechanism an endless chain 97 is trained to have straight
upper and lower stretches which extend in the feed
direction. The lower stretch of each chain 97 is secured
to the inner carriage 50, and hence, as that chain stretch
moves forward or backward, driven by the motor 9D, the
inner carriage is constrained -to move with it in the feed
direction or the re-turn direction.
The mo-tor 91 that drives -the outer
;~ carriage 51 is similarly drivingly connected, through
a reducing gear box 98, with a ro-ta-table drive shaft
99 that is parallel to the drive shaft 93. Like the
shaf-t 93, drive shaft 99 has a sprocket 100 secured
to each of i*s ends, but the sprocke-ts lDO overlie the
r
,t ~
_ 3~ -
~3~;~3
outer flanges 55 of the I-beams. A second ~reely rot~table
sprocket 102 is moun-ted at the front of the feed mechanism,
over each o~ -the I-beams, in line with each of the driving
sprockets 100, and an endless chain 103 is trained around
- each driving sprocket 100 and its aligned front sprocket
102~ The lower stretch of each such chain 103 i5 connected
with the outer feed carriage 51.
A sensor lQ4, 105 is provided for each
of-the feed carriages 50, 51, respectively, to produce
outputs that enable the computer to monitor and control
the positions of the carriages along the I-beams 52. As~ ;
shown, the sensors 104, 105 are connected with the respective
drive shafts 93, 99 through which the carriages are
propelled in their feeding and return motions.
'~. Assuming that the ~eed carriages 50 and
E::
51 have the relationship shown in FIG. 3, with the inner
carriage 5~ support.ing the front portion of a log and the
outer carriage 51 supporting its rear portion, the jaw
elemen-ts 5S, 56 on the respective carriages will maintain
'' 20 their grips on the log unti]. the front end o* the log has
entered the bite of the feed rolls 15.. At that point the
inner feed carriage 50 will have reached the limit of its :~
motion in the feed direction, and its jaw elements 56
: are disengaged from -the log. The front end portion of the
. log is then supported, guided and driven in the *eed
direction by the feed conveyor 13 in cooperation with
the feed.rolls 15, while the rear end portion of the log
continues to be supported by the outer feed carriage 51,
which of course continues to move in the feed direction.
35 -
~33563
As soon as the jaw elemen-s 56 of the
inner carriage 50 are disengaged from the log,,-they
are s~ung up -to their inopera-tive position~ and the
inner carriage can move in the return direction to
a posi-tion sui-table for supporting the next log,
~hieh is by then moving towards the feed mechanism
on the transfer mechanism carriage 35. In moving
to that position, the inner feed carriage 50 of
course passes the outer carriage 51, which continues
to support the rear end portion of the log and to
move in the feeding direction. The p,oint at which
the inner carriagelstops its return motion depends
upon the length of the log then on the transfer
mechanism carriage and can be controlled au-tomatically
in response to signa~s concerning the detected length
o~ that log. The carriage positîon sensor 104 is
~; of course employed for purposes o such automatic
control. -~
When the outer carriage 51 reaches the
forward limît of i*s feeding stroke, whîch îs at about
the location from ~hich the inner carriage began îts
~` return movement, its jaw arms 65 are swung apart to
be disengaged from the log, and it can îmmedîately
begîn a return movement. During feedîng of the log
~,' just released, -the outer carriage 51 was in the traili~g
posî~îon, but ~or feedîng the next log it will be
în the leading posîtion; and therefore îts return
motion is a relatîvely short one and very quîckly
, . .
accomplîshed. It wîll be seen that for each successîve
~`,;30 log the carriages 50, 51 reverse the'ir leading-trailîng
" ~
. ~ .
' - 36 -
63
rela-tionship. If the logs are end-aligned on the
~ransverse plane 18, as is preferred, the leading
carriage - whichever one it may ~e - can always start
its feeding movement from the sarne location, a small
distance behind the transverse plane 18, to which
location each carriage can be brought au-tomatically
with the aid of outputs from the sensors 104, 105.
From the foregoing description of the
jaw shifting devices on the feed mechanism carriages,
comprising the respective adjustable leng-th links 72
and 88, an obvious modification of the method and
apparatus of this invention will suggest itself to those
skilled in the art. The pa;rs of jaws on the transfer
mechanism 9 could be provided with shifting de~ices
generally similar to those for the jaws on the feed
mechanism carriages, and in that case the log would
undergo no movement whatsoever as it was being transferred
from support by the log supports at the measuring station
8 to the sets of jaws on the transfer mechanism 9~ since
the transfer mechanism jaws would be self adjusting. Hence
all scanning could be accomplished before the log was gri.pped
by the sets of jaws on -the transfer mechanism. ~hen, by
controlled shifting of the transfer mechanism jaws, the
log could be brought to an orientation at which the calculated
pIane K in i-t would be in the re~uired relationship to
the cutting plane S immediately before the log was engaged
by the jaws of the feed mechanism. The jaws o~ the feed
mechanism would -then adapt themselves to the lateral
orientation of the log as they converged upon it, and when
30 they engaged the log it would be in the desired position
and orientation for feed to the cutting machine so that
-~ feeding motion could begin at once.
- 37 ~
~. ~ .-. .
3~i;3
Another obvious modification of the herein
disclosed invention would elimina~te suppor-ts at the measuring
sLation that would engage the irregular side surface o,
the log~ like the chain arms 22, 23, and would replace them
with coaxial elements for engaging the opposite end surfaces
of the log, said elements defining an axis extending through
the log and about which the log would be controlledly
rotatable~ Such supporting elements could comprise a pair
of taper pins or a pair of rotatably mounted elemen-ts of
the -type disclosed in U.S. Patent No. 3,l90, 323 ~ to
N~T.G. Johansson and therein referred to as "a toothed
s-triking member." In any case, rota-tion of the log would
be controlled from the instant that scanning c`ommenced.
Since theilog would undergo no lateral shîfting in the course
'
of its rotation, calculation would be simplified and would
probably be more accura-te~ but the log handling mechanism
might have to be more complicated if processing delays were
to be avoided. The jaws on the transfer mechanism would
~ have to~be self-adjus-ting~ to avoid any lateral shif-ting
of the log during i-ts transfer from -the supporting elements
to the measuring station, and then it would be unnecessary
to subject the log to another scanning after i-t was in the
grip of the transfer mechanism. At -the possible cost of
; some productiorl delay, the coaxial supporting elements that
gripped the ends of the log could be mounted on the transfer
mechanism, to replce the jaws 41 thereon, and the log would
then be supported by those elemen-ts both during scanning at
the measuring station and during transfer to the ~eed line;
but such an arrangement would avoid production delays only
; 30 if multiple sets of supporting elements were arranged in
~ a complex and presurnably space-consuming carrier mechanism.
"~:
38 -
3~3
Finally, it has been assumed for
purposes of simplifica-tion in most of the forego-ng
explanation that the reference plane Ml is parallel to -the
cutting plane S, and that the carriage 35 of the transfer
mechanism moves with a purely translatory motion through a
lixed dis-ance denoted by X in FIG. 8c. Such an arrange-
ment is preferred. But conceivably the carriage of the
transfer mechanism, or its equivalent, could move in a
curved path (e.g., be carried by swinging arms), and in
tha-~ event the re*erence plane would be inclined to the
cutting plane. Nevertheless, the two planes Ml and S
would still hava to be in a known and *ixed relationship
to one another, and the carriage ~or its equivalent) o~
the transfer mechanism would move along a de~ined,
I
: predetermined path through a known and fixed dîstance so
that at the conclusion of its motion the log carried by
the transfer mechanism would have its calcu~ated plane K
in the same relationship to the cutting plane S tha-t it had
; ~ to the reference plane Ml just before transfer motion
20 began, except insofar as the position and orientation of
the log might be corrected by shiftable jaws on the -transfer
mechanism.
.:
To summarize~ the method of this invention
enables an elongated, irregularly shaped workpiece such ,r
~ ..
as a log to be established in an optimum orientation on
a feed mechanism by which the workpiece is fed through a
~; cutting machine and by which the workpiece is carried
in translatory substantially lengthwise motion along a
cutting line parallel to a cutting plane defined by the
30 cutting machine. As a result, cuts are made by the
cut-ting machine that are parallel to the cutting plane
,
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3~3
and a-t predetermined dis-tances from i-t, which c~-ts
?roduce optimum yield from -the finished workpiece.
According to -the method, the workpiece is ~irst es-tablish.ed
at a measuring station which is spaced from -the cutting
line and defines a reference plane Ml tha-t is in a kno-~m,
- I ixed relationship to the cutting plane. At the measuring
station the workpiece is substantial]y confined to
rotational motion and is disposed approximately lengthwise
parallel to the reference plane. The workpiece is
scanned photoelectrically at the measuring station to
establish -the locations of a substantially large number o~
points on its surace relative to a predetermined
coordinate system comprising the reference plane tFIG. 8a),
and on the basis of scanning data, a calculation i5 made of
a calculated plane K that lies in the workpiece and moves
with it, which calculated plane, for optimum yield, should,
during cutting, be parallel -to the cutting plane and at a
: required distance from it. While the workpiece is at the
cut-ting station, it is established in a rotational position
(FIGS. 8b, 8c~ such that any line lying in said calculated
plane K and extending transversely to the lengt~ of the
workpiece is parallel to the reference plane, and -the
lateral relationship ~X', ~X'I) between said calculated
plane and the reference plane is ascertained. The wo~kpiece
i. is transported .from the measuring station to the feed line ..
.. by means of a transfer mechanism comprising carriage means
constrained to move along a predetermined path and through
a predetermined distance (e.g~, distance X, FIG. 8c); and
~: the workpiece is constrained to partake of all motion OI
~! the carriage means so that it can arrive at the feed
line with i-ts calcula-ted plane K in the same relationship
. . .
~0
. , -, . ., ., :. . :
to the cutting plane S tha-t it had to the reference plane Ml
just before the workpiece left the measuring station (FIG~ 8d~
The wor~piece is transferred from supporting means on the
carriage means comprising the transfer mechanism -to other
supporting means on other carriage means comprising the feed
mechanism, such transfer being efIected in a manner to prevent
any moLion of the workpiece while the transfer takes place.
Between the time that the workpiece leaves the measuring
station and the time when feed motion begins, by a lateral
shifting of the supporting means o~ one of said mechanisms,
relative to the carriage means o that mechanism, the workpiece
is established with its calculated plane parallel to the
cutting plane and at the required distance from it tin FIG. 8d~
jaws 56 and 57`are laterally shif-ted to bring ~X' and~X"
.
equal to ~ero).
:;~
From the foregoing description taken with
the accompanying drawings, it will be apparent that this
invention provides a highly efficient appa-ratus for feeding
: '
~ successive logs -through a cutting machine that maintains a
steady flow of;logs through the cutting machine without
substantial delay between successive logs and also enables
each log to be individually posi-tioned and oriented for optimum
yield in accordance with its particular geometry.
Those skilled in the art will appreciate
that the invention can be embodied in forms other than
as he-~eindisclosed for purposes of illustration.
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