Note: Descriptions are shown in the official language in which they were submitted.
CA 02271609 1999-OS-13
AUTOMATED PRECISION LOG PRE-POSITIONING
AND LOG TURNING SYSTEM
BACKGROUND OF THE INVENTION
Field of Invention
The present invention relates generally to the field of sawmill equipment.
More particularly, the present invention relai:es to a device for providing
fast and
precise log positioning in a sawmill setting. More particular yet, the present
invention involves an improved log turner for automated precise turning and
positioning of raw logs before and during sawing.
Description of Prior-art
While the general lumber industry involves many problems associated with
obtaining an increased yield of lumber from raw logs of lesser and lesser
quality,
the more specific problem of obtaining the highest yield of logs from raw
lumber
during the sawing process will be discussed) herein. In the sawmill industry,
it is
becoming more common to automate the: processing of raw logs into end
products as automation offers significant advantages in terms of processing
speed, reliability, and cost. It should be noted that this discussion is
limited to the
specific field of sawmill processes for the sole purpose of illustrative
clarity and is
not meant to limit the intended scope of the invention.
In handling raw logs during any sawmill operation, the logs are generally
carried on conveyor belts between processing equipment that performs specific
tasks on the logs. For example, in the processing of logs into sawed lumber,
there are a number of steps involved. First, a group of raw logs are processed
by
equipment that separates the group into individual logs. Each individual log
is
then processed by de-barking equipment. The logs are then fed on a conveyor
past scanning equipment that analyses the cross-sectional area of each log and
determines the orientation of the log for maximum recovery or conversion into
saleable product. An example of such scanning equipment can be found in U.S.
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CA 02271609 1999-OS-13
Patent No. 4,139,035 issued to Bystedt Ea al. where a log is positioned via
scanners to determine a preferred saw line. In prior-art devices such as
Bystedt
et al., the log is then passed by orienting equipment that rotates the log to
the
desired orientation and onto the sawing equipment that cuts the log into raw
lumber. An additional step may also involve cutting the logs into set lengths
at
some stage in the process. An important part of this automatic processing of
logs
as outlined above is the orientation of the lod to ensure maximum recovery.
Conventional equipment known as "flying vertical rolls" have also been
developed to adjust the orientation of logs in response to control signals
generated by computer scanning equipment. The scanning equipment
determines the angle to which a log should be rotated and the "flying vertical
rolls" carry out the rotation of the log about its longitudinal axis.
Conventional
equipment comprises one or more pairs of spaced, upstanding spike rolls
positioned on either side of a conveyor belt that define a passage through
which
a log to be rotated passes. The spike rolls are cylindrical members with
radially
extending spikes to grip and engage the log. The upstanding spike rolls are
driven to rotate about their vertical axis thereby causing a log in the
passage
befinreen the rolls to be advanced forward. The term "flying" in the name of
the
equipment refers to the fact that the log moves continuously through the
passage
even as it is being oriented. The spike rolls .are also adapted for movement
along
the vertical axis about which they rotate. Moving a spike roll on one side of
a log
along the vertical axis while maintaining the position of the spike roll on
the other
side of the log causes the log to rotate to a new angle.
In addition to the "flying vertical roll" equipment, there more commonly
exists the "Hill-type" turner equipment. Based upon technologies perfected
during the last century by the William E. Hill Manufacturing Company of
Kalamazoo, Michigan, Hill-type turners have: endured for more than 100 years
as
the predominant sawmill device for turning r<~w logs. Hill-type turners are
devices
that include a vertical bar having pivoting teeth. The bar travels
tangentially
upward against the face of a log allowing the protruding teeth to engage the
log
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CA 02271609 1999-OS-13
and force it to rotate. The bar also rocks back and forth towards and away
from
the log face to allow for irregularities in the log surface.
While earlier versions of the Hill-type turner were actuated via steam
pistons, contemporary versions utilize current hydraulics to actuate the
vertical
bar. However, operation of such Hill-type turners has remained virtually
unchanged such that manual control by a sawmill operator is required. Such
manual control occurs via a control handle that is rocked leftlright for
corresponding up/down movement of the vertical bar. The control handle is
rocked forward and back for related back and forth movement of the vertical
bar
towards and away from the log face. Such manual control is an acquired skill
that
is highly subject to the vagaries of human error. Indeed, many months of
costly
training is involved for a sawmill operator to even become productive in using
a
Hill-type turner and mastery of such manual control is rare.
Various known devices exist that opE:rate fundamentally the same as the
Hill-type turner. That is to say, such known devices exist for orienting logs
that
effect log rotation by tangentially applying forces to the log surface. For
example,
U.S. Patent No. 3,269,432 issued to Mello>ht et al. discloses a vertically
oriented
chain for rotating a log against a fixed abutment. Even more recently, U.S.
Patent No. 4,102,229 issued to Pryor et al. discloses a log turner having a
rectangular hollow bar that includes pivotable teeth. The bar is manipulated
for
tangential movement astride a log so as to allow the teeth to pivot when
contacting the log. Vertical movement of the bar then transfers rotational
motion
to the log via the teeth in order to effect a lod turn.
Such prior-art devices, while relativel~,r simply constructed and maintained,
limit the efficiency of a log cutting operation because each exhibits
cumbersome
movement of the log. Further, time-consuming steps are needed to prevent axial
rotation of the log while the log is being engaged and rotated to the desired
orientation by the log turner. Accordingly, an otherwise continuous line of
production is interrupted. Moreover, once the given prior-art device turns the
log,
the log is unclamped and able to roll back to an undesirable orientation while
it is
progressing to a subsequent processing station.
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CA 02271609 1999-OS-13
Although, the "flying vertical roll" and "Hill-type turner" equipment do
perform log rotation, these types of prior-art turners suffer from the
significant
drawbacks that accurate angular rotation of a log is difficult to achieve.
Further,
lengthwise skewing of the log is not practical using the prior-art devices.
The
calculations needed for such vertical movement of one or more spike rolls or
toothed bars to rotate a log through a selec~~ted angle is quite complex.
Because
a log is essentially a tapered cylinder, rotating the log axis through a given
angle
by a tangential vertical movement at the perimeter of the log will depend on
the
circumference of the log at the point of engagement of the spike rolls.
Therefore,
it is necessary to take many variables into account.
Such variables include, among others, the feed speed of the log through
the equipment, the time of engagement with the spike/teeth, and the overall
surface irregularities of each log. These variables are needed to be able to
calculate the circumference of the portion of the log that is engaged by the
spike/teeth when the log is to be rotated. Further, raw logs tend to have a
curvature or "sweep" that must be taken into account when determining the
vertical movement of the spikelteeth. It is readily apparent that the accuracy
of
operation of the prior-art devices is greatly diminished by the asymmetrical
nature
of raw logs having knots or other defects. Such asymmetrical defects in the
log
will result in slippage of the spikelteeth along the log. In sum, it is
extremely
difficult to achieve optimum angular positioning of a raw log using such
"flying
vertical roll" and "Hill-type turner" equipment.
Indeed, none of the prior-art references discussed above adequately
provide for the finesse necessary to quickly and accurately position raw logs
to
enable the best cuts of lumber from any given log. Contemporary improvements
in these prior-art devices have been limited to cumbersome designs that
combine
useful log-scanning technologies with sorely antiquated log-turning
technologies.
The prior-art devices do not provide any features that would quickly and
accurately allow total scanning of each log so as to pre-position the log.
Further,
the prior-art devices do not provide any features that would quickly and
4
CA 02271609 1999-OS-13
accurately provide re-positioning of the log between cuts. Such ineffective
log
positioning using the prior-art devices not only results in slower production
of
lumber, but also results in undesirable waste of raw lumber due to inaccurate
positioning and cutting even in the presence of current scanning technologies.
Accordingly, it is desirable to provide for a new and improved, effective
positioning device for such purposes as, but not limited to, log pre-
positioning
and turning during sawmill processing. What is needed is such a positioning
device that substantially automates sawmill operation during all stages -
i.e.,
scanning, pre-positioning, cutting, and turning stages. What is also needed is
such a positioning device that increases production of lumber with a related
reduction in waste. What is further needed is such a positioning device that
can
be used either to replace antiquated systems entirely or enhance the
efficiency of
a contemporary scanning system using antiquated turning elements. Still, what
is
needed is such a positioning device that is able to operate in cooperation
with
computerized scanning equipment and does not require excessive modifications
to do so. Still further, what is needed is such a positioning device that
includes
both rotational and skewing capabilities, all while requiring relatively few
mechanical parts. Yet still further, what is needed is such a positioning
device
which overcomes at least some of the disadvantages of the prior-art while
providing new and useful pre-positioning, turning, and skewing features.
SUMMARY OF THE INVENTION
It is an objective of the present invention to provide a new and improved,
effective automated log pre-positioning and turning system that provides
precision pre-positioning of raw logs and highly accurate turning of such logs
along with skewing movement during sawmill processing. It is another objective
of the present invention to provide such an automated log pre-positioning and
turning system that utilizes computerized automation of sawmill operation
during
all stages including scanning, pre-positioning, cutting, and turning (with
skewing)
without human intervention. Thus, the preaent invention substantially
eliminates
human error and related waste of mill time and log resources. Another
objective
5
CA 02271609 1999-OS-13
of the present invention is to provide such an automated log pre-positioning
and
turning system that entirely replaces antiqu<3ted systems or may be used in-
part
to replace antiquated turning elements so as to increase the efficiency of a
contemporary scanning system still using such antiquated turning elements.
Still
another objective of the present invention is to provide an automated log pre-
positioning and turning system that delivers increased finesse in manipulation
of
raw logs while not interfering or jeopardizing other sawmill processes. Yet
still
another objective of the present invention to provide an automated log pre-
positioning and turning system that operates in cooperation with computerized
scanning equipment without requiring excessive modifications to do so. Such an
automated log pre-positioning and turning system includes both rotational and
skewing capabilities, yet requires few mechanical parts.
The present invention is directed to <~n automated log pre-positioning and
turning system that includes a hydraulically actuated log manipulating
mechanism
with an integrated C-shaped element (hereinafter "positioning unit") useful
for, but
not limited to, sawmill purposes such as capturing, positioning, skewing,
rotating,
and transporting logs. In addition to the hydraulically actuated log
manipulating
mechanism with its positioning unit, the overall inventive system includes a
stop
and loader section, a conveyor section, a scanning section, a carriage
section,
and a sawing section. The stop and loader section provides a means for loading
raw logs from a log deck one at a time into a pre-positioning area. Within the
pre-positioning area, the conveyor section provides a means for conveying a
log
through a trough into a roller area. In the roller area, turning wheels rotate
the
log at least one complete rotation so that the scanning section can
electronically
scan the log. This electronic scanning functions to capture the log's
dimensional
information, calculate the optimal cutting solution for the given log, and
output
operational commands to the log manipulating mechanism, the carriage section,
and the sawing section.
Moreover, after the log passes through the scanning area, the log
manipulating mechanism is utilized to capture the log within the positioning
unit.
In response to computer-generated operational commands derived from the
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CA 02271609 1999-OS-13
scanning process, the log manipulating mechanism moves to secure the log
within its positioning unit and rotate and skew the log to the log's
predetermined
best opening face (BOF). The BOF represents the initial lengthwise cut to the
log
that will optimize the quality and quantity of the resulting lumber. Once
rotated
and skewed to the BOF, the log is deposited onto the carriage section by the
log
manipulating mechanism. The carriage section includes multiple headblocks that
hold the log onto a movable carriage. Each headblock moves in response to the
given shape of the log. That is to say, the headblocks are actuated (e.g.,
hydraulically, electromechanically, ..etc.) in response to computer commands
derived from the scanning process such that the multiple headblocks together
conform to the given log shape. While the headblocks might be aligned
identically for a very straight log, they may each be positioned drastically
differently for a particularly crooked or knotty log.
The headblocks in the carriage section will maintain the log on the
movable carriage. The movable carriage is movable in two directions and allows
for multiple passes through the sawing section. The first direction moves the
BOF (and subsequent cuts) past a bandsaw, or similar sawing device, in a back
and forth motion along the length of the log. While the sawmill described
herein
is a carriage-type sawmill, it should be noted that any type of sawmill will
benefit
from the features of the present invention. A single pass results in a single
cut of
lumber from the log. After each pass, the movable carriage incrementally moves
the open face of the log towards the bandsaw. This results in varying lumber
thickness according to the given increment of movement. This is continued
until
the pre-determined point for log turning is reached. That pre-determined point
having been calculated during the scanning process.
At that pre-determined point where all cuts on the first face (BOF and the
successive cuts) have been made, the loc,~ manipulating mechanism will again
capture the log and rotate the log by eith~ar a quarter turn (90°) or a
half turn
(180°). According, to the commands derived from the scanning process,
additional skewing may or may not be necessary. Though it should be noted that
it is possible to skew the log at any time while the log manipulating
mechanism
7
CA 02271609 1999-OS-13
holds it. This becomes a critically useful feature when a raw log having a
significant sweep is encountered. After such rotation (with or without
skewing) to
the second face to be cut, the log manipulating mechanism will re-deposit the
log
into the carriage section. Again, the headblocks will adjust to the changing
shape
of the cut log so as to secure the log for several passes into the sawing
section.
This cutting, re-positioning, cutting process is repeated until all possible
cuts
have been made and all lumber acquired from the given log. At such point, a
new
log enters the system and is milled accordingly.
An important aspect of the present invention is that the next log to be
milled may be deposited into the conveyor section and scanned while the last
cutting passes are being made to the previous log. In this way, the log
manipulating mechanism can deposit the next log onto the carriage section upon
completion of the final cut of the previous log. This allows the immediate
commencement of the cutting of the next log. This elimination of any required
log adjustments on the movable carriage prior to cutting virtually keeps a tog
constantly in the sawing section. This reprE~sents a substantial benefit over
prior-
art positioning systems and turning devices
Overall, it should be understood that elements such as conveyors, rollers,
carriages, bandsaws, electronic scanning equipment, computer controllers,
hydraulic cylinders, electrical solenoids, wiring harnesses and electrical
connection devices, and various related and similar devices may be used within
the present invention. However, the specificity of such related and similar
devices is a secondary consideration as compared to the primary features
embodied in the present invention. That is to say, the log manipulating
mechanism and its incorporation into and inter-relation to the inventive
system as
a whole is considered to embody that which is considered the invention.
Further,
it should be readily apparent that many diffE:rent combinations of such
related and
similar devices may be utilized within the inventive system in cooperation
with the
log manipulating mechanism without straying from the intended scope of the
present invention.
8
CA 02271609 1999-OS-13
The invention will be described for the purposes of illustration only in
connection with certain embodiments; however, it is to be understood that
other
objects and advantages of the present inv~sntion will be made apparent by the
following description of the drawings according to the present invention.
While a
preferred embodiment is disclosed, this is not intended to be limiting.
Rather, the
general principles set forth herein are considered to be merely illustrative
of the
scope of the present invention and it is to be further understood that
numerous
changes may be made without straying from the scope of the present invention.
BRIEF DESCRIPTION OIF THE DRAWINGS
FIGURE 1 is a side view of the log manipulating mechanism and its C-
shaped positioning unit according to the preferred embodiment of the present
invention shown in operation with a carriage section and partially cut log.
FIGURE 2 is a top view of the inventive system showing multiple logs
entering the system and one log within the positioning unit of the log
manipulating
mechanism that is shown in FIGURE 1.
FIGURE 3 is a side view of the log manipulating mechanism taken alone
according to the preferred embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is directed to a computerized log positioning system
useful in a sawmill setting. The inventive system includes a novel log
manipulating mechanism having a positioning unit. The log manipulating
mechanism is preferably used in combination with an overall sawmill system
that
includes a stop and loader section, a conveyor section, a scanning section, a
carriage section, and a sawing section. Although a carriage-type sawmill is
preferred, the present invention can be adapted for use within any type of
sawmill. Further, each section is fully computer controlled in a manner
consistent
with current technologies an interconnected through standard connecting
devices
9
CA 02271609 1999-OS-13
- e.g., electrical wiring and cabling, hydraulic hosing and tubing, ...etc.).
More
specifically, a system operator can oversee and override operation of the
inventive system, but normal operation including log loading, scanning,
positioning, and cutting are accomplished in response to computer generated
commands. While a preferred configuration of the overall system will be shown
in
the drawings, this should be considered as a general preference for
descriptive
purposes. Accordingly, for illustrative clarity, the present invention will be
described hereinbelow in specific detail only with respect to the novel log
manipulating mechanism. All other system components being generally
discussed only insofar as necessary to enable the utility of the log
manipulating
mechanism to one of ordinary skill in the sawmill art.
Referring now to FIGURE 1, therE; is shown a side view of the log
manipulating mechanism 10 in accordance with the preferred embodiment of the
present invention. The log manipulating mechanism 10 includes a positioning
unit 12. The positioning unit 12 is preferably C-shaped and dimensioned so as
to
substantially surround logs sized for lumber uses (e.g., three foot diameter
logs).
The positioning unit 12 is rotatably situated within the end of the log
manipulating
mechanism 10. A log 11 is shown having its BOF already cut. The log 11 is
shown secured within a headblock 20. Tlhe headblock 20 includes a dogging
mechanism 21 that clamps the log 11 down atop a movable carriage 22. The
movable carriage 22 is able to move via wheels 22a and 22b along rails 23 and
24, respectively, in a direction parallel to the length of log 11. Movement
along
the rails 23, 24 is actuated by way of hydr<~ulics via a carriage traverse
cylinder
25. Additionally, the movable carriage 22 is able to move in a direction
perpendicular to the length of log 11 via a headblock cylinder 26. This dual
movement of the movable carriage 22 will become more apparent with reference
to FIGURE 2 below.
With continued reference to FIGURE 1, the log manipulating mechanism is
seen to include a baseframe 30 that includes rails 31 (one hidden). Mounted to
the baseframe 30 is a support 35. The support 35 is attached to the rails 31
via
CA 02271609 1999-OS-13
bearing mounts 32 and 33. A baseframe cylinder 34 is provided and attached
between the baseframe 30 and support 35. The baseframe cylinder 34 is a
hydraulic cylinder which, when activated, causes the support 35 to ride along
the
rails 31. Such movement by the log manipulating mechanism 10 is shown by
dotted element 10a where it can be seen how the log manipulating mechanism 10
is able to fit beside the headblock 20 and movable carriage 22. This reveals
how
the positioning unit 12 is able to deposit the log 11 into the position as
shown
from the position shown by dotted lines 11a. Specific structure on the log
manipulating mechanism 10 related to log positioning will be discussed later
with
respect to FIGURE 3.
With final reference to FIGURE 1, the support 35 of the log manipulating
mechanism 10 includes a pivot mount 3.6. The main body 38 of the log
manipulating mechanism 10 has a pivot 37 that connects to the pivot mount 36.
As steel or some relatedly durable alloy is. preferably used to fabricate the
log
manipulating mechanism, it becomes apparent that the forces acting upon the
pivot 37 within the pivot mount 36 are grE:at. In order to facilitate raising
and
lowering the positioning unit 12 (and any giiven accompanying log held
therein),
the heavy steel main body 38 is held against pivoting movement via a lifting
cylinder 40. The lifting cylinder 40 is mounted between the support 35 and the
main body 38. Since most weight of thE~ log manipulating mechanism 10 is
therefore taken up by the pivot mount 36. and the lifting cylinder 40, arcuate
movement about the pivot 37 only requires the use of a fine positioning
cylinder
39. Similar to the lifting cylinder 40, the fine positioning cylinder 39 is
mounted
between to support 35 and the main body 38. However, the fine positioning
cylinder 39 is designed to react faster than the lifting cylinder 40 to effect
small
vertical adjustments of the main body 38 and thus adjustments of the grasped
log
(see 11 a).
FIGURE 2 is a top view of an automated precision log pre-positioning and
log turning system 100 according to the ipreferred embodiment of the present
invention. The system 100 shows the log manipulating mechanism 10 as seen in
11
CA 02271609 1999-OS-13
FIGURE 1 along with multiple headblocks 20, a log deck 50, a stop and load
section 51, a conveyor section 52, a scanning section 53, a carriage section
54, a
sawing section 55, and a control cab 56. It is preferred that the system 100
include at least the above-mentioned general elements 10, 20, and 50-56.
However, it should be understood that the specific type of headblocks 20, log
deck 50, stop and load section 51, conveyor section 52, scanning section 53,
carriage section 54, a sawing section 55, and control cab 56 may be altered
without straying from the intended scope o~f the inventive system.
Accordingly,
the following discussion of operation of the system 100 will be discussed in
general terms with respect to elements 20 and 50-56 as such elements are
sufficiently known in the sawmill art.
In operation, multiple logs 50a-50d are ushered along the log deck 50 (in
the direction shown by directional arrows) towards the stop and load section
51.
The stop and load section 51 stops the rolling logs 50a-50d and loads each log
one at a time onto the conveyor section 52. The conveyor section 52 operates
in
a manner similar to any conventional conveyor belt in order to move a log 50e
into position within the scanning section 53. The scanning section includes a
means for rolling the log 50e through .at least one complete turn
(360°).
Preferably, a pair of rollers 53a and 53b are provided as such a means though
any suitable roller trough may be used. Within the scanning section 53, there
is
included an electronic scanner (not shown) that will scan the entire log
during the
complete turn by rollers 53a and 53b. This provides a digital map of the given
log 53e. The digital map is then utilized wuthin a computerized controller 56a
to
find the best cutting solution for the log including the BOF with which to
begin
cutting.
Using the best cutting solution, the controller 56a outputs commands to all
actuators located throughout the system 100 to automatically: 1 ) position
each
log to its BOF upon the carriage section 541 via the log manipulating
mechanism
10; 2) adjust each headblock 20 to accept the given uniquely-shaped log and
secure it to the movable carriage 22; 3) pass the log face through the sawing
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CA 02271609 1999-OS-13
section 55 and incrementally move the movable carriage 22 towards the cutting
element during each pass; 4) re-position the log upon the carriage section 54
by
a quarter turn (90°) or a half turn (180°) via the log
manipulating mechanism 10;
and 5) repeat steps 3 and 4 until the log is completely sawn according to its
best
cutting solution. In order to further enhance continuous operation, the next
log
50a will be scanned and pre-positioned within the log manipulating mechanism
during the last passes of the previous Ic~g 50e through the sawing section 55.
It should be noted that all related wiring needed to allow the controller 56a
to
control the various actuators of the system '100 is of the type readily known
in the
10 computer controller art and has been omitted for the sake of clarity.
While general components may b~e used within the system 100 for
elements 20 and 50-56 within the functional constraints delineated above, the
components of the log manipulating mechanism 10, and more particularly the
positioning unit 12, will be discussed in specific detail with respect to
FIGURE 3.
FIGURE 3 is a side view of the log rnanipulating mechanism 10 according
to the preferred embodiment of the present invention. The log manipulating
mechanism 10 includes the positioning unit 12 that is rotatable within the
main
body 38 of the log manipulating mechanism 10. Such rotation is accomplished
via two drive chains 63 and 64 that are coupled together via a change-up gear
69. The drive chain 63 is looped around a series of pulleys 70-73. The pulleys
are mounted to the main body 38 of the log manipulating mechanism 10.
Specifically, pulleys 70 and 71 are mounted via pulley supports 70a and 71a,
respectively. Winding around pulleys 78 and 79 and along the outer
circumference of the positioning unit 12, the drive chain 64 is affixed to the
end
tips of the C-shaped positioning unit 12. The ends of the other drive chain 63
are
affixed to a link 75 that is, in turn, attached i:o a rod end 74 of a series
of cylinders
60, 61, and 62. Cylinder 62 being secured to a cylinder mount 77 that is
affixed
to a cylinder support 76. The cylinder support 76 is affixed to the main body
38 of
the log manipulating mechanism 10.
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CA 02271609 1999-OS-13
Upon actuation of any one of cylinders 60, 61, and 62, the rod end 74 will
be linearly actuated and thereby move the drive chain 63. The drive chain 63
will
then rotate the change-up gear 69, which then rotates the drive chain 64 and
thus
rotates the positioning unit 12. More specifically, actuation (i.e.,
expansion) of
cylinder 60 will create a clockwise quarter turn (90°) of the
positioning unit 12.
Actuation (i.e., expansion) of both cylinders 60 and 61 will together will
create a
clockwise half turn (180°) of the positioning unit 12. Actuation (i.e.,
retraction) of
only cylinder 62 will create a counter-cllockwise quarter turn (-90°)
of the
positioning unit 12. Smooth rotational movement of the positioning unit 12 is
assured via rollers 68 that are mounted on the main body 38 of the log
manipulating mechanism 10 and peripherally spaced around the positioning unit
12. Such rotational movement provides rotation of any log placed within the
positioning unit 12. Retention of such a log is accomplished via clamps 66a
and
67a that are actuated, respectively, via clamp cylinders 66 and 67. Such
actuation of clamp cylinders 66 and 67 functions to retract clamps 66a and 67a
as can be seen via the dotted lines of retracted clamps 66a' and 67a'.
While rotational movement of any clamped-in log is apparent by the
discussion above, the skewing movement is best described with reference to
both
FIGURES 2 and 3. In FIGURE 2, skewing cylinders 65 and 65' are shown. Each
skewing cylinder 65 and 65' operates independent of one another. In FIGURE 3,
it is seen that each skewing cylinder (only 65 is visible) operates a skewing
plate
65a. By activating either skewing cylinder 65 or 65', the related skewing
plate will
push the log in a manner so as to skew the log. This skewing movement
combined with the vertical movement of thE~ fine positioning cylinder 39 and
the
rotational movement derived from one or more of cylinders 60, 61, and 62
creates
a multitude of positional movements. Further, each of the skewing cylinders
65,
65', the fine positioning cylinder 39, and the cylinders 60, 61, and 62 for
rotational movement are operated automatically via the controller 56a in
response
to the pre-determined commands created during scanning. This results in a fast
and accurate positioning of a log during sawmill operations.
14
CA 02271609 1999-OS-13
It should be understood that the preferred embodiment mentioned here is
merely illustrative of the present invention. Numerous variations in design
and
use of the present invention may be contemplated in view of the following
claims
without straying from the intended scopE~ and field of the invention herein
disclosed.
