Note: Descriptions are shown in the official language in which they were submitted.
CA 02271175 1999-OS-OS
HIGH SPEED REVOLVING BOARD SINGULATOR WITH RETRACTING SHOE AND
VARIABLE DWELL DUCKERS
Field of the Invention
This invention relates to an apparatus for the singulation or allocation of
lumber
into lug spaces on a lugged transfer, or other lumber conveying device, and in
particular relates
to an apparatus capable of collecting, singulating, allocating and
consistently spacing, rough sawn
lumber or planed finished lumber, or sticks of varying widths, thickness and
lengths into
consecutive spaced-apart lugs, or allocated spacings onto a transfer, or
lugged transfer, or to a stick
placing device, at high speeds.
Background of the Invention
Conventional lug loaders or singulators (hereinafter collectively referred to
as
either lug loaders or singulators) have been found to be inadequate at higher
feed speeds. They
are also limited in their ability to both singulate and allocate lumber. When
lumber is of varying
widths and varying in thickness, or bowed, as may be predominant in curve
sawing mills, cupped
or crooked, it becomes increasingly difficult to handle the lumber at
desirable higher speeds.
An example of a conventional lug loader is that taught in United States Patent
3,923,142 which issued to Rysti on December 2, 1975. In that patent the means
for stopping work
pieces prior to being singulated is only briefly mentioned. In particular,
what is being taught is
singulating boards by use of supporting arms rotating around a closed loop,
the orientation of the
2 5 supporting arms controlled by curved deflectors. Pressing arms in opposed
radial pairs, are
rotatably mounted above the supporting arms to synchronously clamp a board
onto a supporting
arm. Downstream flow of the mat of boards is arrested by a stop on each
supporting arm. None
of the advantages of the synchronized duckers of the present invention are
taught or suggested.
Rysti also does not disclose a mechanism for allocating or missing a lug
space, especially at high
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CA 02271175 1999-OS-OS
speeds. The need to miss lug spaces arises for example where it is desirable
to "cut-in-two" a long
piece of lumber to meet mill requisites. In a "cut-in-two" situation there is
a need to create an
empty lug space behind the board. To achieve a "cut-in-two", a drop saw
including a device to
lift and set the cut length into the following lug space is provided up-stream
on the lugged transfer.
At high speed, deliberately and accurately missing a lug space, which it is an
object of the present invention to provide, requires a fast acting method to
momentarily deactivate
all feed and clamping devices, and subsequently to reactivate those apparatus
in the brief time
available as the closely spaced lugs are rotated past the singulator.
It is also an object of the present invention to provide for specific board
allocating
patterns required in the delivering of spacing sticks to a stick placer and
its associated stacker to
allow placing of sticks on lumber packages possibly having different package
lengths.
Applicants are also aware of United States Patent 5,518,106, which issued to
Allard on May 21, 1996. Allard discloses using fixed pick-up shoes mounted
onto rotating discs
for engaging and supporting boards being singulated. Fixed shoes however, have
the disadvantage
that they may mark the underside of the board as the board is translated over
the top of the disc
and as the board is released. If a board is planned or finished, for example
destined for cabinet
2 0 making or the like, then any marks from the shoe or overhead clamp will
reduce the value of the
board. Allard also discloses a speed-up belt to pull the board away from the
fixed shoes at the top
of the disc to prevent the board from being flipped over as the board is
released from the shoes.
In some mills the boards have been marked for trimming and grading before the
lug loader. Thus
if the board has been flipped over by the singulator, as may occur in the case
of the Allard device,
2 5 the board must be flipped back by hand to read the mark. This can be
difficult in a high speed
application.
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CA 02271175 1999-OS-OS
Many lug loaders in the prior art, particularly those operating at slower feed
speeds, require that, in order to stop the delivery of boards to the
singulator, the board mat moving
downstream into the singulator device must be pushed back upstream by the
stopping means, that
is, forced away from the fixed pick-up shoe and clamping device. Worse yet, in
some prior art
devices the board delivery mechanism must be brought to a complete stop. Both
pushing the mat
of boards back upstream, and stopping the board delivery mechanism, can be
impractical at high
speed, a problem which is not adequately dealt with in the prior art.
It is therefore an object of the present invention to produce an apparatus
wherein
the delivery of boards is more controlled, with a simple means for stopping,
activating and
deactivating both a clamping means and a rotating pickup shoe simultaneously,
allowing more
precise and faster pick-up and delivery of spaced and allocated boards.
It is further an object of the present invention to produce an apparatus that
has a
quick acting stopping device for stopping the flow downstream of a board mat
adjacent the
singulator, wherein the stopping device has an adjustable dwell.
It is yet another object of the present invention to produce an apparatus that
reduces the likelihood of leaving marks on the board by the pick-up and
clamping device.
It is still another object of the present invention to produce an overhead
clamping
apparatus that can be retrofitted to existing lug loaders of the general type
to improve the speed
and consistency of delivery of boards by said existing lug loaders.
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Summary of the Invention
The high speed revolving lug loader of the present invention consists of a
board
infeed transfer, whereat the boards collect at a plurality of hook stops, so
as to abut each other to
form a mat of boards. The downstream-most boards in the mat are released by
the hook stops and
picked up by a plurality of shoes. The shoes are carried in a semi-circular
arc on rotating discs.
The boards are clamped down onto the shoes by an overhead clamping means. The
plurality of
shoes are pivotally mounted on the rotating discs. The overhead clamping means
are timed to
coincide with the riming of the rotation of the shoes on the rotating discs so
that a clamp is applied
to a board being carried on a shoe. The clamp and shoe interact to pickup and
clamp boards so
as to deliver the boards individually and sequentially to a lugged transfer,
or to allocate boards or
sticks to a delivery transfer for a stick placer of the general type.
Each shoe is elongate. One end of each shoe is pivotally mounted to its
corresponding rotating disc. The opposite end of each shoe supports a cam
follower. The cam
follower protrudes from the shoe so as to ride on the cam surface of a cam.
The cam is selectively
rotatably mounted on a hub shaft, collar or sleeve that may have a common axis
of rotation with
the axis of rotation of the rotating disc. The cam is selectively rotatable,
independently of rotation
of the rotating disc. The cam is asymmetric about its axis of rotation so as
to provide a cam lobe
2 0 for actuation of the shoe into engagement with the underside of a board to
be singulated when the
cam is rotated to elevate the lobe from a non-actuating position to a shoe
actuating position.
With the cam in the shoe actuating position, as a shoe is rotated on the
rotating
disc, the cam follower rides on the cam surface up over the cam lobe thereby
forcing the board
2 5 pickup surface, or, otherwise, the board engaging and supporting surface
on the shoe against the
underside of the board, urging the board upwardly so as to be carried in a
transition arc along an
arcuate path defined by the arcuate translation path of the shoe and the
arcuate, upwardly exposed,
radially outermost edge of the rotating disc. The cam surface smoothly merges
from the cam lobe
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CA 02271175 1999-OS-OS
to a radially retracted position relative to the radial extension of the cam
lobe, so that in its
actuated position the board transitions from being carned by the shoe, to
being supported by the
radially outermost edge of the rotating disc as the shoe retracts radially
inwardly of the radially
outermost edge of the rotating disc as the board is carned in the translation
arc along the arcuate
path.
Thus, as the cam followers, follow a cam profile which cause the shoes to come
around in to a level orientation to pickup the board, the shoe pickup surface
will be level when the
board is engaged by the shoe. The duckers are timed to retract as the shoes
lift the board. As the
cams followers follow the profile of the cam, the shoe pickup surface
gradually tilts or inclines
to follow an optimum trajectory between the board's pickup position and the
board's subsequent
position. The overhead clamping means contacts the board as the board is
carried over the rotating
discs, that is, follows the arcuate path. The cam profile is shaped so that
the shoe orientation
changes to approximately coincide with the different tangent angles of the
average trajectory that
the different width and thickness of boards will follow as the boards are
picked up and delivered
to the outfeed transfer.
In one embodiment, the cam may be rotatably mounted, for example but without
intending to be limiting, by means of a bearing hub, to the same shaft that
supports the rotating
2 0 discs. It is understood that such a cam, and other actuating cams in the
present invention, although
depicted as being mounted on a common axle with other structural elements of
the present
invention, are free floating on such axles and because they are not tied to
the rotation of such axles
may also be independently mounted on other supporting structure. In any event,
the cam is held
in a steady position, that is, it is not rotated, until it is desired to stop
feeding the boards. A
2 5 linkage is connected to a cam cylinder. The cam cylinder (or other
selectively actuable device)
actuates to rotate the cam lobe, for example so as,to rotate the cam lobe down
so that the shoes are
retracted behind or beneath the duckers and not exposed. Thus retracted, the
shoes miss the board
being held by the ducker. At the same time that the cam is rotated down, a
linkage holds the
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CA 02271175 1999-OS-OS
ducker or duckers up so that they do not release the board, but rather, stop
the flow of boards from
the board mat on the infeed chains.
The duckers are operated mechanically by a ducker cam, which is adjustably
mounted to the same common shaft as the rotating discs. The ducker or duckers
can also be
controlled by other means such as a directly connected actuable cylinder or
other linkage system.
No matter how the ducker is actuated it must be held in its up or elevated
position when the cam
lobe is rotated down, or the infeed would continue to push boards into and
onto the continuously
rotating discs.
A sensor may be positioned to detect the position of the shoes, so that the
rotation
of the cam (deactivation of pickup shoes) will not be done while the shoes are
about to pick up,
or are just picking up a board. The sensor advantageously includes the ability
to stop the actuation
of the cam cylinder for a period in time corresponding to the time period the
shoes are in the board
pickup area, that is, actuation of the cam cylinder to rotate the cam would be
paused for the
appropriate time to suit the different speeds that the machine may be set to.
Another way to
accomplish this would be to have two sensors, one to detect the shoe as it
enters the pickup area
and another to detect the shoe as it leaves the pickup area.
2 0 Where sawmills require that the widths of boards being separated vary
widely, that
is, from very narrow boards such as 2 inches by 2 inches, to boards 10 inches
and wider, a dual
ducker system can be used. In this situation there are two separate ducker
systems, where both
systems include separate ducker cams independently actuating separate first
and second duckers
laterally spaced apart across the board flow path. The first and second
duckers stop the boards at
2 5 a common position along the flow path. The second duckers, are lowered
leaving the first duckers
to restrain downstream movement of the boards onto the singulator. The
downstream-most board
is released in a timed manner to register the released board with the next
shoe rotating around on
the rotating discs into cooperating position. As the board is released by the
first duckers, the
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CA 02271175 1999-OS-OS
second duckers are raised quickly by a second ducker actuator, thereby
preventing' the next
upstream board from being inadvertently released prior to the rotation of the
next shoe into
position.
The reason for this dual ducker system is that when using the cam operated
ducker
system, the cam profile that lowers and raises the duckers cannot be too
radical without requiring
heavier springs etc. and consequently extra costs and wear points. The
secondary ducker system
allows the use of the same basic cam profile as that operating the first
duckers, only operating a
little earlier, that is, with its timing advanced over the primary or first
duckers, so as to achieve
rapid, controlled, singulated, board release by the duckers. The duckers
themselves are
improvements over the use of, for example, pins which must be fully lowered
before a board is
released. The duckers are rotated down and slightly downstream as they are
lowered allowing the
board to be released to commence movement prior to the ducker being fully
lowered.
In an alternative embodiment, the shoes are not pivotally mounted on rotating
discs, but rather on a pair (or plurality) of endless circulating chains. This
arrangement also allows
the shoes to continue to carry the boards into the lugged transfer for more
controlled delivery of
the boards. The shoes are timed so that the boards are delivered to the back
of the passing lugs
so that the next pair, or group of lugs are rotated on the transfer chain to
come up and around the
2 0 transfer chain sprockets to meet the trailing edge of the board so as to
carry the board in the lug
space. This provides more control for delivering wider boards, that is, boards
12 inches and more
wide, because the boards do not ride over an arcuate path over the radius of
the top of the rotating
discs, but are carned substantially flat on the chain, gripped between the
shoes and any overhead
clamping device. The boards are carried by the endless circulating chains,
right up to and into the
2 5 lug spaces on the transfer chains.
In the preferred embodiment, the overhead clamping means for gripping the
boards
onto the shoes, as the shoes are in motion, includes a array radially spaced
of flexible elongate
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CA 02271175 1999-OS-OS
members mounted on a rotatable overhead shaft. The overhead shaft is mounted
over the duckers
so as to engage the radially outermost ends of the flexible elongate members
down onto the
leading edge of the board held by the duckers as the board is lifted by the
shoes. The flexible
elongate members contact the board so as to hold the board onto the shoes as
the board is carried
along the arcuate path on the rotating discs. In one embodiment, the flexible
elongate members
are resilient finger-like shafts which resiliently flex as the board is raised
and comes up to the top
of the arcuate path defined by the rotating discs. The array of flexible
elongate members rotating
on the overhead shaft at a rotational speed so that the ends of the flexible
elongate members
translate in the same direction and at the same speed as the board and
corresponding shoes. At
a position just past the top and center of the disc, the flexible elongate
members may engage a
fixed roller. The fixed rollers, or other rigid means of further flexing the
flexible elongate
member, flexes the elongate member to disengage the end of the elongate member
from the board.
The fixed rollers may be mounted above the rotating discs, downstream of the
overhead shaft on
which the array of elongate members is mounted. In the absence of fixed
rollers or the like, the
flexible elongate members may cause the board to flip over as the flexible
members are rotated
on the overhead shaft so as to translate the ends of the elongate members
across the top of the
rotating discs. The fixed rollers inhibit boards having a square cross-
section, such as a 4 inch by
4 inch board or the like from being rolled over, and also inhibit smaller
boards from being flicked
ahead prematurely as the flexible elongate members begin to unflex or extend
as the boards
2 0 translate on their arcuate path away from the elongate member.
An alternative overhead clamping means is a rotating shaft having a pin or
crank
boss. A plunger rod is attached. The position of the overhead crank is such
that, when the plunger
rod is rotated down, a fixed stop guides the plunger rod so that the plunger
rod is angled. The
2 5 plunger rod thereby contacts the top of the leading edge of a board as the
board was being picked
up by the shoes. The plunger rod presses the board down onto the shoes as the
shoes rotate around
on the discs. The plunger rod may have a resilient length compression means
such as a
telescoping or resilient coupling or joint to allow the plunger rod to
compress to accommodate
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CA 02271175 1999-OS-OS
even very thick boards. Thus as the board translates in the arcuate path over
the rotating discs, the
plunger rod holds a relatively and approximately constant pressure onto the
board. As the board
passes the apex of the arcuate path, that is, the top of the rotating discs,
the momentum of the
board carries the board onto the out feed transfer. The plunger rod is then
rotated up, so as to lose
contact with the board. The plunger rod then swings on the crank pin so as to
fall back onto the
fixed stop, where the plunger rod is again angled to come down onto the next
board. Depending
on the operation speed of the singulator, the plunger rod may have a direct
linkage means to return
the plunger rod in a timed sequence to the fixed stop.
In a further alternative embodiment, the overhead clamping means may be a
circulating resilient belt.
In summary, the lug loader of the present invention includes a first shaft
rotatably
mounted transversely across a board flow path, wherein a board in the board
flow path is aligned
transversely across the board flow path. The board translates in a downstream
direction on a board
infeed transfer from an upstream position. A board supporting structure such
as a disc or chain
is mounted to the first shaft so as to rotate with rotation of the first
shaft. The board supporting
structure has a shoe mounting surface generally orthogonal to the first shaft.
The board supporting
structure also has a radially outer-most rim, radially outer-most relative to
the first shaft. The rim
2 0 is generally circumferentially contiguous so as to form a board supporting
surface around the rim.
An elongate shoe has first and second ends. A board supporting heel is mounted
on the shoe.
The shoe is pivotally mounted at the first end of the shoe to the shoe
mounting surface. A cam
follower is mounted to the shoe so as to protrude from the shoe away from the
shoe mounting
surface.
A cam is independently selectively rotatably mounted on the first shaft or on
other
supporting structure that allows actuation of the cam, collectively and
without intending to be
limiting referred to as a cam support. The cam cooperates with the cam
follower. The cam has
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CA 02271175 1999-OS-OS
a cam surface lying generally in a first plane, the first plane adjacent to
and generally parallel with
the shoe mounting surface. The cam surface is a radial cam distance from the
cam support. The
rim is a radial rim distance from the cam support. The radial cam distance is
less than the radial
rim distance. The cam surface defines a first cam lobe which is asymmetric and
radially extends
about the cam support relative to a non-extended circumference of the cam
surface. The first cam
lobe is generally on an upstream side of the cam. The non-extended
circumference of the cam is
generally on a downstream side of the cam. The cam lobe is selectively
rotatable, by selective
rotation of the cam by a cam actuator, between an upwardly rotated shoe
actuating position and
a downwardly rotated shoe non-actuating position. The cam follower lies
generally in the first
plane and co-operates with the cam surface so as to ride over, in surface-
following contact with,
the cam surface on the upstream and downstream sides of the cam, as the board
supporting
structure rotates about the cam support relative to the cam. The cam lobe when
in the shoe
actuating position drives the board supporting surface on the shoe radially
outwardly of the rim
as the cam follower rides over the cam surface corresponding to the cam lobe.
The lug loader of the present invention further includes a selectively
actuable
board retainer and sequencer at a board holding location in the board flow
path, adjacently
upstream of the board supporting structure. The board when retained in the
board retainer is held
in the holding location for sequenced release onto the board supporting
surface of the shoe as the
2 0 shoe is rotated over the cam lobe when the cam lobe is in the shoe
actuating position. The board
is thereby translated along a transfer path over the board supporting
structure onto a board outfeed
transfer so as to singulate the board from an upstream mat of boards upstream
of the board
retainer.
2 5 The lug loader of the present invention may further include a rotatable
resilient
board clamp. The clamp is rotatably mounted over the board supporting
structure and cooperates
with the shoe so as to pinch the board between the resilient clamp and the
board supporting surface
on the shoe as the board is translated along the transfer path. In one
embodiment, the resilient
CA 02271175 1999-OS-OS
clamp may be a resilient elongate finger or shaft-like member rotatably
mounted on a second shaft
above, and parallel to, the first shaft. The shaft-like member is generally
vertically oriented as a
lower end of the shaft-like member pinches the board onto the shoe. The shaft-
like member is
rotatable in a vertical plane about the second shaft. Advantageously, the
shaft-like member is a
flexible arm extending radially outwardly of the second shaft. Further
advantageously, the board
clamp includes a radially spaced array of the flexible arms, radially spaced
about the second shaft.
Alternatively, the shaft-like member may be a resiliently telescoping shaft.
The
resiliently telescoping shaft may in one embodiment be a rotating plunger
mounted by an
offsetting Garner, linkage, disc or the like (collectively, a carrier) so as
to be offset relative to a
carrier shaft such as the second shaft. A plunger guide directs the plunger so
as to press the free
end of the plunger against a board being carried on a board supporting surface
of the lug loader,
such ; as a shoe. The offsetting of the plunger causes, firstly, the plunger
to be resiliently
longitudinally compressed against the board as the second shaft rotates
synchronously with
rotation of the first shaft to pass the board under the second shaft, and,
secondly, the plunger to
be lifted free of the board once the board has passed under the second shaft.
In a preferred embodiment, the lug loader of the present invention includes a
radially spaced apart array of the shoes, radially spaced around the first
shaft.
In one aspect of the present invention, the cam is generally kidney-shaped in
the
orthogonal plane. The cam surface immediately downstream of the cam surface
corresponding
to the cam lobe merges from a convex sector of the cam surface onto a concave
sector of the cam
surface. An acute angle is thereby formed between the board supporting surface
on the shoe and
2 5 the rim. As the cam follower on the shoe rides over the cam surface
corresponding to the cam lobe
when the cam lobe is in the shoe actuating position, the acute angle is
reduced so as to translate
the board along the transition path in a generally flat orientation.
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It is understood that in the lug loader of the present invention the board
supporting
structure may be a body of rotation, axially symmetric about the first shaft.
In a preferred
embodiment, the body of rotation is a disc lying generally in a plane
orthogonal to the first shaft
and the shoe supporting surface is a surface of the disc. Advantageously, a
plurality of parallel
spaced apart discs are provided, spaced apart along, and orthogonal to, the
first shaft. The shoe
mounting surface is a surface on each disc of the plurality of discs.
In a further aspect of the present invention, the board retainer and sequencer
is a
first ducker arm. The first ducker arm is rotatably mounted to a first
supporting means and
selectively actuably rotatable about the first supporting means between a
board retaining position,
wherein the board is retained in the holding location, and a board releasing
position wherein the
board may translate along the transition path on the shoe. The first ducker
arm rotates in the
downstream direction when rotating from the board retaining position to the
board releasing
position.
A first ducker timing cam is mounted on the first shaft. A first ducker cam
follower is mounted to the first ducker arm for cam following cooperation with
the first ducker
timing cam. The first ducker timing cam is mounted on the first shaft in a
first radial orientation
relative to the first shaft so as to lower and elevate the first ducker arm
for release of the board
2 0 synchronously onto the shoe. Advantageously, the first supporting means is
a shaft mounted
below the infeed transfer and the first ducker arm, in the board releasing
position, is reclined in
the downstream direction.
Further advantageously, the board retainer and sequencer further includes a
second
2 5 ducker arm selectively rotatably mounted on second supporting means. The
second ducker arm
is selectively rotatable about the second supporting means independently of
the rotation of the first
ducker arm about the first supporting means. The second ducker arm is
selectively actuably
rotatable about the second supporting means between a board retaining
position, wherein the board
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CA 02271175 1999-OS-OS
is retained in the holding location, and a board releasing position wherein
the board may translate
along the transition path on the shoe. The second ducker arm rotates in the
downstream direction
when rotating from the board retaining position to the board releasing
position.
A second ducker timing cam is mounted on the first shaft. A second ducker cam
follower is mounted to the second ducker arm for cam following cooperating
with the second
ducker timing cam. The second ducker timing cam is mounted on the first shaft
in a second radial
orientation radially spaced from the first radial orientation relative to the
first shaft so as to lower
and elevate the second ducker arm for release of the board synchronously onto
the shoe.
The second supporting means may be a second shaft mounted below the infeed
transfer. The second ducker arm in the board releasing position may be
reclined in the
downstream direction.
In a further aspect, the board supporting structure may be an endless chain
rotating
around first and second sprockets mounted respectively on said first shaft and
on a parallel shaft
parallel to and spaced from said first shaft. The chain is advantageously
generally level along an
upper segment thereof extending between said first and second sprockets.
Further advantageously,
a fixed track extends parallel to said upper segment of said chain, downstream
of said cam and
2 0 cooperating therewith so that said cam follower passes from said cam
downstream onto said track.
The track is oriented to maintain said board supporting surface on said shoe
above an outfeed
chain.
The invention provides other advantages, which will be made clear in the
2 5 description of the preferred embodiments.
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Brief Description of the Drawings
The invention will be better understood by reference to the accompanying
drawings, wherein:
Figures 1, 2, 3 and 4 are side elevation views according to the preferred
embodiment of the invention showing various stages as the boards are lifted by
the shoes and
being placed into the lugged transfer in a sequence;
Figure 1 a is, in perspective view, the disc cam and board lifting shoe
arrangement
of the lug loader of the present invention;
Figure 5 is a side elevation view according to the preferred embodiment of the
invention showing cam 36 rotated down to disengaging shoes 22;
Figure Sa is, in perspective view, the disk cam and ducker arrangement of the
lug
loader of the present invention in an alternative embodiment;
Figures 6, 7 and 8 are side elevation views according to an alternate
embodiment
2 0 of the invention showing the optional dual ducker system for faster
mechanical ducker timing
controlling the flow of narrow boards. The secondary ducker 48 is shown up
front of the primary
ducker 18;
Figures 6a-6d illustrate, in side elevation view, the operation of the
staggered disc
2 5 cams and corresponding duckers according to the lug loader of the present
invention in an
alternative embodiment;
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Figure 6e is a perspective view of the staggered disc cams and duckers of
Figures
6a-6d;
Figures 9, 10 and 11 are side elevation views according to an alternate
overhead
pincher means;
Figure 12 is a side elevation view according to the preferred embodiment
showing
an optional roller and guide for the overhead pincher means;
Figure 12a is, in partially cut-away perspective view, a board hold down
device
according to one embodiment of the present invention;
Figures 13, 14, and 15 are side elevation views of another alternate
embodiment
showing chains carrying the shoes.
Detailed Description of Preferred Embodiments
Referring to the drawing figures wherein similar characters of reference
represent
corresponding parts in each of several views, the lug loader of the present
invention is generally
2 0 indicated by the reference numeral 10.
As seen in Figures 1-4, lug loader 10 includes a support frame constructed of
various vertical and horizontal structural supports 12. An infeed transfer 14
delivers boards 16 to
the lug loader 10. A plurality of spaced-apart timed duckers 18, two or more
depending on the
2 5 length of the board, are spaced apart laterally across infeed transfer 14,
that is along the length of
the board 16. Duckers 18 hold board 16 for selectively timed release from a
holding location at
the downstream end of a mat of boards 16 formed behind duckers 18. Rotating
discs 20 are rigidly
mounted to, so as to rotate on, shaft 24 in direction A. Shoes 22 are
pivotally mounted to discs
CA 02271175 1999-OS-OS
20 in radially spaced apart relation around shaft 24. Cam followers 22a extend
outwardly,
generally perpendicularly, from shoes 22 as better seen in Figure 1 a. Cam
followers 22a position
shoes 22 as the cam followers 22a follow cam 36.
Cam 36 is rotatably mounted on shaft 24, for example, by means of hub 25. Cam
36 may be selectively rotated on hub 25 in direction C relative to discs 20,
for example, by means
of an actuator mounted to pin 36a. Cam 36 has an optimized profile defined by
cam surface 36b
that cam follower 22a follows in the upper quadrants of cam surface 36b.
Cam followers 22a are held on cam surface 36b by their own weight and the
weight of shoes 22 including shoe pad 22b and the elongate arm of the shoes
extending between
pivot pins 20a on discs 20 and the cam followers. Thus, as shoes 22 are
rotated in direction A on
discs 20, they hang down freely, suspended by corresponding pins 20a, during
their rotation
through the lower quadrants of their travel path, and are oriented during
their rotation through the
upper quadrants of their travel path by cam followers 22a sliding or rolling
over cam surface 36b.
Cam lobe 36c is asymmetrically bulbous in a plane orthogonal to shaft 24. The
orientation of cam 36 about shaft 24 on hub 25 dictates whether cam lobe 36c
is elevated or
lowered between, respectively, a shoe actuating position (seen in Figures 1,
la, 2-4) and a shoe
2 0 non-actuating position (seen in Figure 5). In the shoe actuating position,
cam lobe 36c is elevated
so that cam follower 22a riding on cam surface 36b over cam lobe 36c drives
shoe pad 22b
radially outwardly beyond the radially outer-most edge 20b of discs 20. The
shoe actuating
position of cam lobe 36c coincides with the radial position, relative to shaft
24, of a board 16
(shown in dotted outline in Figure la) held by duckers 18 in their holding
location adjacent the
2 5 upstream side of discs 20. Thus, with cam lobe 36c in its shoe actuating
position, as discs 20
rotate in direction A so to are rotated shoes 22, driving shoe pads 22b in
direction D into
engagement with the underside of the board 16 in the holding location.
16
CA 02271175 1999-OS-OS
In the shoe non-actuating position, cam lobe 36c is rotated so as to be
lowered, so
that shoe pad 22b on shoe 22 is not driven in direction D but, rather, remains
below, i.e. radially
beneath, edges 20b of discs 20. Board 16 is thereby not engaged, but left in
the holding location.
In operation cam 36 may be rotated down into its shoe non-actuating position
so
that shoe pad 22b will miss board 16 in a high speed disengage mode. Board 16
is held by
duckers 18.
As shoe 22 is rotated by rotation of disc 20, shoe pad 22b travels at an
optimized
angle, so that board 16 remains in contact with shoe pad 22b as much as
possible while board 16
is lifted and transferred over disc 20 by shoe 22.
Clamping means such as overhead pincher 28, has in one preferred embodiment,
although not intended to be limiting, mounted thereto, so as to protrude
radially therefrom, a
plurality of resilient members such as flexible arms 28a. Pincher 28 rotates
on shaft 30 in
direction B. Fixed roller 32 may be provided so that flexible arms 28a contact
roller 32 when
the flexible arm in contact with the a board 16 is no longer required to press
board 16 down onto
shoe 22. Fixed roller 32 thereby transfers control of board 16 to outfeed
transition chain 34.
Roller 32 disengages flexible arm 28a from board 16 by deforming or flexing
flexible arm 28a
2 0 against roller 32 as pincher 28 rotates in direction B. Transition chain
34 may be running at the
same rotational speed as discs 20, or it may be running at a higher speed so
as to advance the
board 16 for delivery.
The ends 29 of flexible arms 28a and shoes 22 converge as they counter-rotate
to
2 5 clamp or pinch, and subsequently lift, board 16 as overhead pincher 28
rotates on shaft 30 and
shoes 22 rotate in their arcuate travel path on discs 20.
17
CA 02271175 1999-OS-OS
As better seen in Figure S, cam lobe 36c is selectively rotated between its
lowered
shoe non-actuating position and its elevated shoe actuating position by the
selective actuation of
cylinder 37. Extension of the cylinder rod from cylinder 37 rotates linkage
member 37a in a
direction counter-clockwise as viewed in Figure 5 so as to tension turnbuckle
37b. Turnbuckle
37b is pivotally mounted at its ends, the lowermost end of turnbuckle 37b
pivotally mounted to
the uppermost end of linkage member 37a, and the uppermost end of turnbuckle
37b pivotally
mounted to pin 36a on cam lobe 36c. Linkage member 37a is itself pivotally
mounted on shaft
46.
Also commonly rigidly mounted on shaft 46 is linkage actuating arm 44a. Roller
44b is mounted on the uppermost end of linkage actuating arm 44a so as to
contact a lower surface
on the lowermost end of linkage member 44. Linkage member 44 is pivotally
mounted at its
upper end on shaft 42. Commonly rigidly mounted on shaft 42 is a ducker 18 or,
in the preferred
embodiment, a spaced apart array of duckers 18 all mounted in the same radial
relationship about
shaft 42 relative to linkage member 44 so that rotation of linkage member 44
about shaft 42
actuates ducker 18 or simultaneously actuates the array of duckers. Extending
the rod from
cylinder 37, rotates linkage actuating arm 44a counter-clockwise as viewed in
Figure 5 so as to
rotate linkage member 44 and ducker 18 clockwise thereby engaging stop 18b on
the upper end
of ducker 18 against the downstream most edge of the downstream most board 16
in the mat of
2 0 boards held on infeed transfer 14.
Thus, actuating cylinder 37 so as to extend the rod from the cylinder
simultaneously rotates cam lobe 36c into its shoe non-actuating position and
raises ducker 18 or
the array of duckers so as to interrupt the downstream flow of boards 16. This
allows the
2 5 deliberate skipping, that is, the allowing of lug spaces between lugs 38a
on lug chain 38 to go by
while the singulator is effective disabled although the rotating disc and
shoes remain rotating. To
re-enable the singulator, cylinder 37 is actuated so as to retract its rod
thereby simultaneously
elevating cam lobe 36c into the shoe actuating position and releasing ducker
18 or the array of
18
CA 02271175 1999-OS-OS
duckers so that the actuation of ducker 18 or the array of duckers is governed
by a ducker cam 40
as better described below.
As seen in Figure Sa when ducker 18 is not locked in its elevated position by
the
operation of cylinder 37, ducker followers 18a are free to ride on cam surface
40a as ducker cam
40 rotates on common shaft 24. Thus, with cam lobe 36c rotated into the
elevated shoe actuating
position, ducker follower 18a is free to ride on ducker cam surface 40a.
Ducker cam lobes 40b
are radially spaced apart about shaft 24 on cam 40 and are also radially
spaced about shaft 24
relative to shoes 22 on rotating disc 20. Disc 20 is mounted laterally spaced
from cam 40 on shaft
24. Cam lobes 40b are radially spaced relative to shoes 22 so that as shoes 22
rotate around lobe
36c so as to engage the underside of the downstream most board 16 held by stop
18b on ducker
18, ducker 18 is lowered. Ducker 18 is lowered as ducker follower 18a follows
into the depression
ahead of cam lobe 40b. Ducker 18 is thus lowered as board 16 is lifted by shoe
22. As board 16
is lifted and rotated in a downstream direction on shoes 22, cam lobe 40b then
engages ducker
follower 18a so as to raise ducker 18 and stop 18b to arrest the downward
movement of adjacent
board 16 in the board mat on infeed transfer 14.
Ducker follower 18a follows on cam surface 40a under the force of gravity,
ducker
18 being free to rotate about shaft 42. It will be appreciated that at higher
feed speeds required
2 0 of the singulator to place boards into the spaces between lugs 38a, for
example, when the outfeed
transfer chain and lugged chain are rotating at higher speeds, it is necessary
to actuate duckers 18
between their lowered board releasing position and their elevated board flow
stopping position in
a short period of time so as to assist in singulating the boards onto the
shoes and thence onto the
outfeed transition chain. Unfortunately, at higher feed speeds, the curvature
of cam surface 40a
2 5 becomes an increasingly radical curvature to the point where ducker
follower 18a will jump from
cam surface 40a due to the radical curvature and rapid rate of change of
curvature due to the
increased rotational speed of cam 40. This results in loss of accuracy of the
timing of the lowering
and elevating of ducker 18.
19
CA 02271175 1999-OS-OS
Consequently, in one preferred embodiment, a dual ducker system is employed
where a first ducker 18 or array of duckers 18 is actuated spaced apart in
time from actuation of
a second ducker 48' or array of laterally spaced apart secondary duckers 48'
as better understood
with reference to Figures 6, 6a-6e. Unless disabled by mechanisms similar to
that described
above in respect of the linkage attached to cylinder 37 as seen in Figure 5,
duckers 18 and
secondary duckers 48' follow the cam surface curvature of their corresponding
ducker cams 40 and
40'. Duckers 18' and corresponding cam or cams 40' are generally identical to,
and operate in the
same way as duckers 18 and cams 40. That is, cam followers 48 follow the
curvature of cam
surface 52a in a similar fashion to the interaction between cam followers 18a
on cam surfaces 40a.
The shape of cam surface 52a is similar to that of cam surface 40a.
In the embodiment as illustrated, the second duckers 48, which are pivotally
mounted on shaft 50, actuate in time slightly ahead of actuation of duckers
18. This is
accomplished by radially spacing apart about shaft 24 the actuating cam
curvature of cam surfaces
40a and 52a relative to each other so that, in the embodiment illustrated, as
the cams rotate in
direction a in unison with rotating disc 20, the smoothly curved indentation
in cam surface 40a
leads the corresponding smooth indentation on cam surface 52a so that ducker
or duckers 18 are
lowered before secondary ducker or duckers 48 are lowered and subsequently
ducker or duckers
2 0 18 are elevated before secondary ducker or duckers 48. Typically the
radial spacing of the
corresponding actuating curvature of cam surfaces 40a and 52a will fall within
the range of 3 - 10
degrees. This approximately corresponds to spacing apart in time of the
actuation of duckers 18
and secondary duckers 48 within the approximate range of 20 - 70 milliseconds
given a typical
rotational speed of shaft 24 in the order of 0.4 revolutions per second
(approximately 25 RPM).
2 5 As may be seen, in the illustrated preferred embodiment, cams 40 and 52
each have 3 actuating
curvatures equally radially spaced apart around corresponding cam surfaces 40a
and 52a relative
to shaft 24.
CA 02271175 1999-OS-OS
Thus as seen in sequence illustrated in Figures 6a - 6d, as shaft 24 rotates
discs 20
and cams 40 and 52 in direction A, as a shoe 22 is being rotated into position
to pick up a board
16 (where in Figures 6a - 6d the shoes are not illustrated for sake of
clarity) it is required to lower
both duckers 18 and secondary duckers 48. This is done in sequence first by
lowering, for
example, secondary duckers 48 as illustrated which is then sequentially
followed in time by
lowering of duckers 18. Once the board has been picked up by shoes 22, the
duckers have to be
elevated. Once again in the example illustrated the secondary duckers lead and
are elevated before
elevation of duckers 18. In this fashion each set of duckers whether it is
duckers 18 or duckers
48, are given time to follow a more smoothly curved and less radical curvature
on their
corresponding cam surfaces the end effect being that of a very fast actuation
of a single ducker or
array of duckers 18.
Duckers 18, as controlled by ducker cam 40, are timed to release a board 16
onto
shoes 22 on discs 20 as shoes 22 are rotated into position.
Advancing lugs 38a are timed with shoes 22 on rotating discs 20. The overhead
pincher means 28 and shoe 22 begin to retract back away from the board 16 at
about top center
of disc 20 where the board 16 now contacts the disc 20 and the overhead
pincher means 28.
2 0 Thus, the dual ducker system seen also in Figures 7 and 8 allows for
increased
speed of the cam actuated duckers without the need for using radical ducker
cam profiles in order
to increase the up and down motion of the duckers, this allows for the
handling of very narrow
boards alone or mixed in with wider boards.
2 5 Alternative overhead pinching means include any resilient device for
resiliently
holding a board 16 onto shoes 22, and in particular may include belts (see
Figures 7, 8 and 13-15)
telescoping plungers (see Figures 9-11) and the flexible arms of Figures 1-6,
12 and 12a.
21
CA 02271175 1999-OS-OS
Thus as seen in Figures 9-11, rotating plunger 56 is mounted offset relative
to shaft
58 by means of an offset shaft boss pin 58a on rotating disc 58b. Plunger 56
follows fixed guide
60, down onto board 16 to clamp board 16 onto shoes 22. Rotating plunger 56
includes a resilient
means such as spring 56a. Contact nose 56b on plunger 56 contacts board 16 and
remains in
contact with boaxd 16 while board 16 is lifted up by shoe 22 and translated
over disc 20. Once
board 16 has translated over the top of disc 20, plunger 56 is lifted from
contact with board 16 by
rotating pin 58a on disc 58b. Plunger 56 is then positioned for the next board
16 to be clamped.
As seen in Figures 13-15, in a further alternative embodiment disc 20 is
replaced
with sprockets 64a, 64b and chains 66. Chains 66 rotate around sprockets 64a
and 64b in direction
A. Shoes 22 are rotatably mounted to chains 66. Shoe followers 22a follow cam
36 until reaching
the top center of sprocket 64a, where from shoe followers 22a follow along
tracks 68. Shoes 22
turn around sprockets 70, and continue to follow tracks 68. Below tracks 68
shoes 22 pivot to
hang down until they round sprocket 64a on chain 66 to engage the next board
16. This
embodiment allows shoes 22 to carry boards 16 right into the lug spaces with
very little elevation
change. It also avoids the crown at the top of discs 20, which may assist in
singulating wider
boards which might otherwise hang up on the upstream surfaces of discs 20
because the clamping
between the overhead claps and the shoes releases before the board center of
mass passes
downstream of the top of discs 20.
As seen in Figures 12 and 12a, the preferred embodiment may include an
inclined
guide 72 which allows flexible arms 28a to clear over a 4 inch by 4 inch board
74 yet be able to
spring down onto a 2 inch by 2 inch board 76, when handling mixed variable
thickness in cross
section boards in the board mat in order to hold down all boards, no matter of
what thickness
2 5 within allowable parameters known in the art onto the shoes 22. Guide 72
may cause flexible
arms 28a to flex off to one side to improve board contact as the arms release
from the guide.
22
CA 02271175 1999-OS-OS
As will be apparent to those skilled in the art in the light of the foregoing
disclosure, many alterations and modifications are possible in the practice of
this invention
without departing from the spirit or scope thereof. Accordingly, the scope of
the invention is to
be construed in accordance with the substance defined by the following claims.
23
