Note: Descriptions are shown in the official language in which they were submitted.
215 3 6 3 ~ a i ca 6d~ ~
47695--9 ~IJL 11 l995 6
FLYING LOG 'l'UKN~
This invention relates to apparatus for han~l~n~g of
logs, and more particularly, to apparatus for rotating a
5 log to be processed about its longitn~inAl axis.
In the log processing 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.
In any processing operation handling raw logs, 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
15 group of raw logs are processed by singulating 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. 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 the automatic processing of
logs as outlined above is the orientation of the log to
ensure-maximum recovery. Equipment known as "flying
vertical rolls" have been developed to adjust the
orientation of logs in response to control signals
generated by computer sc~nning equipment. The RCAnn;ng
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 longitn~;nAl axis.
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Conventional equipment comprises one or more pairs of
spaced, upstAn~;ng 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 upstAn~ing spike rolls are
driven to rotate about their vertical axis thereby
causing a log in the passage between 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.
The "flying vertical roll" equipment does perform
its job of rotating logs, however, it suffers from the
significant drawback that accurate angular rotation of a
log is difficult to achieve. The math needed to
calculate the vertical movements of one or more spike
rolls to rotate a log through a selected 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 into account the feed speed of the log
through the equipment and the time of engagement with the
spike rolls so that the equipment will be able to
calculate the circumference of the portion of the log
that is engaged by the spike rolls when the log is to be
rotated. Logs tend to have a curvature or "sweep" and
this must also be taken into account when determining the
vertical movement of a spike roll. It is easy to see
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that the accuracy of operation of the flying vertical
roll iæ compromised when one considers that logs are
asymmetrical and knots or other defects in the log will
result in slippage of the log through the spike roll.
The bottom line is that it is difficult to achieve
optimum angular positioning of a log using the flying
vertical roll.
Accordingly, there is a need for log turning
equipment that avoids the drawbacks of the prior art as
set out above. Applicant has developed log turning
equipment that includes gripping members to engage a log
to be rotated and that achieves rotation of the
longitll~inAl axis of the log by rotating the log and the
gripping members as a unit through the desired angle
thereby avoiding the inherently inaccurate rotation
system of the prior art with its reliance on translating
vertical movements into angular rotations of non-
cylindrical logs.
Accordingly, the present invention provides
apparatus for rotating a log delivered by an infeed
conveyor about its longitll~;nAl axis for delivery to an
outfeed conveyor comprising:
a main frame;
a rotatable housing mounted in the main frame having
a passage therethrough to receive a log from the infeed
conveyor;
log gripping means adjacent the passage adapted to
grip the log while permitting continuous forward movement
of the log along its longitll~inAl axis through the
passage to the outfeed conveyor, the log gripping means
being mounted to the rotatable housing for movement with
the housing; and
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drive means to rotate the rotatable housing through
a selected angle to rotate the longitll~; n~ 1 axis of the
log held in the gripping means.
The apparatus of the present invention performs its
rotation of the log to a desired angle while the log is
in continuous longitn~; n~l movement through the apparatus
thus qualifying it as a "flying" log turner.
The log gripping means comprises a plurality of
spike rolls pivotally mounted to the rotatable housing to
accept logs of varying diameter.
Aspects of the present invention are illustrated,
merely by way of example, in the accompanying drawings in
which:
Figure 1 is an elevation view of apparatus for
turning logs according to a preferred embodiment of the
present invention;
Figure 2 is a plan view of the apparatus of Figure
l;
Figure 3 is an elevation view showing the apparatus
engaging a log;
Figure 4 is elevation view showing a hydraulic fluid
distribution system for use with the apparatus; and
Figure 5 is an elevation view of an alternative
hydraulic fluid distribution system.
Referring to Figures 1 and 2, there is shown a
flying log turning apparatus 2 according to a preferred
embodiment of the present invention. As best shown in
Figure 2, the flying log turner 2 acts to rotate a log 4
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delivered by an infeed conveyor 6 about the log's
longitudinal axis 8 for delivery to an outfeed conveyor
10 which transports the oriented log to further
processing equipment (not shown).
As best shown in Figure 1, log turner 2 comprises a
main frame 14 that is mounted to a solid support surface.
A rotatable housing 16 is mounted in the main frame and
has a central passage 18 extending through the housing to
receive a log 4 from the infeed conveyor 6. Passage 18
is surrounded by log gripping means comprising a
plurality of pivoting gripping members 20 that are
adapted to grip the log as it passes through passage 18.
Gripping members 20 are mounted to rotatable housing 16
and move with the housing.
In the illustrated embodiment of Figures 1-3, there
are three gripping member 20 that are pivotable into and
out of central passage 18 and co-operate to engage logs
of varying dimensions as the logs come through passage
18. It will be readily apparent to those skilled in the
art the alternative arrangements of gripping members are
possible for gripping and holding logs as they move
through passage 18. For example, different numbers of
gripping members may be used and the position of the
gripping members can be varied. In the illustrated
embodiment, the gripping members are positioned on
rotatable housing 16 at the end of passage 18 to engage a
log after the front end of the log has already travelled
through passage 18. Alternatively, gripping members 20
can be positioned at the start of passage 18.
Each gripping member 20 comprises a spike roll 22
and an associated actuator comprising a drive motor 23.
Spike roll 22 is a cylindrical body with radially
extending spikes 25 that are engageable with a log. Each
spike roll is mounted to its associated drive motor 23
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for rotary motion about an axis at right angles to the
longitll~; n~l axis of a log moving through passage 18.
Preferably, drive motor 23 is a hydraulic motor, however,
other types of drive units are possible such as electric
or pneumatic motors. When spikes 25 of the various
driven spike rolls engaging a log 4, the log is
continuously moved forward through central passage 18
along the log's longitudinal axis to the outfeed
conveyor.
The gripping members are pivotally mounted to the
rotatable housing 16 at joints 28 to permit movement of
the gripping members in a plane 30 perpendicular to the
longitll~ i n~ 1 axis of a log (see Figure 2). This allows
the spike rolls 22 to be pivoted from a closed position
- 15 shown in Figure 1 in which all spike rolls are pivoted
inwardly into passage 18 for handling small diameter logs
to more open positions as shown in Figure 3 in which the
spike rolls are pivoted outwardly with respect to passage
18 to accommodate large diameter logs.
Gripping members 20 are preferably connected by a
system of pivoting links 38 that allows a single actuator
comprising hydraulic cylinder 40 to adjust the position
of the gripping members between the closed and opened
positions by extending or retracting the cylinder rod 42.
Preferably, cylinder 40 is fitted with a sensor that
detects when the cylinder encounters resistance
indicating that the spike rolls have engaged a log. In
the illustrated example, the actuator that controls the
pivoting link system is a hydraulic cylinder, but it will
be readily apparent that other actuators such as an
electric motor or pneumatic cylinder can be used.
In addition to adjusting the position of the
gripping members, it is desirable to be able to adjust
the position of rotatable housing 16 and central passage
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18 for alignment with the longitn~inAl axis of logs 4 fed
from infeed conveyor 6. Means for adjusting the position
of the rotatable housing comprises an arm 50 pivotally
mounted to the main frame 14 by axle 52. Arm 50 includes
rotatable housing 16 and employs means to pivot the arm
in the form of hydraulic cylinder 55. Cylinder 55
engages against protrusion 56 formed on arm 50 opposite
pivoting axle 52. Cylinder 55 acts to adjust the
position of the rotatable housing between a lowered
position shown in solid lines in Figure 1 and a raised
position shown by dashed lines 57 to accommodate
different diameter logs that are transported to the
apparatus by infeed conveyor 6 which remains at a
constant level.
As best shown in Figure 2, rotatable housing 16
comprises a hollow cylindrical member 60 that extends
through arm 50 and is supported in the arm for rotatable
movement by a bearing 62. To ensure smooth and reliable
rotation of housing 16 multiple bearings can be employed.
The hollow centre of member 60 defines central passage 18
for passage of a log. The front face 65 of cylindrical
member 60 supports gripping members 20 for rotatable
movement. The rear face 66 of member 60 has an attached
drive pulley 62 that is used to rotate cylindrical member
60 with respect to arm 50 and the rest of main frame 14.
Drive means comprising a motor 69 is used to rotate
member 60. Preferably, motor 69 drives a gear reducer 72
through belt 75 and reducer drives pulley 62 through belt
77.
As best shown in Figure 3, when a log 4 is engaged
by spike rolls 22 of gripping members 20, the driven
rolls advance the log through central passage 18 along
the log's longitudinal axis. At the same time, rotatable
housing 16 is rotated by motor 69 to a selected angle to
rotate the gripping members and the engaged log through
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the same angle. The outfeed conveyor 10 is equipped with
press rolls that ensure that the oriented position of the
log is maintained for delivery of the log to downstream
processing equipment.
The apparatus of the present invention is desirably
controlled by conventional sensor equipment (not shown)
upstream of the apparatus to permit automatic operation.
The sensor equipment scans and measures the log to
determine the cross-sectional area of the log and
determines the angle of rotation of the log for maximum
recovery. The sensor equipment then provides a first
control signal to hydraulic cylinder 55 to pivot arm 50
to align with the longitudinal axis of the log and a
second control signal to motor 69 to rotate rotatable
housing 16 through an angle corresponding to the angle
necessary to orient the log for maximum recovery.
As previously mentioned, it is preferable that the
gripping members 20 are driven by hydraulic motors 23 and
positioned by hydraulic cylinder 40. Figures 4 and 5
illustrate various distribution systems for delivering
hydraulic fluid to the hydraulic actuators. It must be
remembered that the hydraulic equipment associated with
rotatable housing 16 must move with the housing
independently of the main frame.
In Figure 4, a first hydraulic distribution system
is shown comprising a manifold 80 fixedly mounted to the
rotatable housing with lines 82 for delivering hydraulic
fluid to operate the hydraulic motors 23 and cylinder 40.
Hydraulic hoses 82 deliver hydraulic fluid from a source
(not shown) through valves 84 to manifold 80, the hoses
being of sufficient length to permit rotation of the
rotatable housing through at least 180 degrees. Hoses 82
are stored or released from about housing 16 as the
rotatable housing is rotated.
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Figure 5 shows alternative hydraulic fluid
distribution means comprising a slip ring or rotary seal
assembly 90 associated with rotatable housing 16. The
slip ring assembly has an outer portion 92 that mounted
to arm 50 and is stationary with respect to the rotatable
housing and an inner portion 94 that moves with the
rotatable housing. The slip ring assembly defines a
reservoir of hydraulic fluid between the inner and outer
portions. A first set of hydraulic hoses 97 connect the
reservoir to a source of hydraulic fluid via ports 95 on
the stationary outer portion. A second set of hydraulic
hoses 96 connect the reservoir of the slip ring assembly
with hydraulic motors 23 and cylinder 40 via ports 98 on
the movable inner portion 94. This arrangement avoids
the need for long hydraulic hoses to accommodate rotary
motion of housing 16.
In the event that electric or pneumatic actuators
are used instead of hydraulic ones, similar power
distribution systems can be used in which the lines carry
electricity or air under pressure rather than hydraulic
fluid.
Although the present invention has been described in
some detail by way of example for purposes of clarity and
understAn~ing, it will be apparent that certain changes
and modifications may be practised within the scope of
the appended claims.
