Note: Descriptions are shown in the official language in which they were submitted.
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BOARD LUMBER POSITION FENCE
Field of the Invention
This invention relates to woodworking machines and more particularly to a
guide
fence or stop for timber in sawmills or sawing machines.
Background to the Invention
In sawmills various timber handling machinery is provided to cut and shape the
timber into wood products such as veneers, board products and the like. In
forming a board product, the tree or flitch material is cut to the desired
cross
section of the three dimensional shape desired for the lumber product being
produced and the piece are then cut to length. When board lumber is handled
within a mill, automation is generally provided throughout the mill to
transport the
material to be cut or worked within the sawmill. Frequently, the board lumber
is
transported from one work position to another on a flat bed roller system.
Once the flitch has been cut to the desired cross section, it is supplied to
saw
equipment for cutting to length. To cut the material to length, one
arrangement of
transport equipment has a conveyor that has a flat bed lug chain transport
table
to carry the lumber pieces toward the length cutting saws. The lumber pieces
are
carried along the conveyor in equidistantly spaced succession based on the lug
spacing of the lug chains. The conveyor has a set of lateral alignment
rollers.
The lateral alignment rollers form a roller bed system placed at right angles
to the
lug chain, which operate to urge one end of the lumber material toward a stop
or
fence. In this arrangement, each successive piece of lumber is spaced from the
other in the direction of travel along the lumber conveyor by the lugs of the
lug
chain and one of the ends of the lumber is laterally aligned to the stop or
fence.
The piece to be cut to length is positioned for contact with a saw. In the
configuration of sawmill conveyor equipment just described, the saw is
stationary
relative to the conveyor and the board is laterally positioned on the conveyor
relative to the saw blade. A positioning fence, which one end of the lumber
piece
abuts against, controls the lateral position of the lumber piece on the feed
conveyor. Numerous prior art arrangements for adjustable positioning fences
for
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use with such a feed conveyor arrangement have been proposed in the past. For
example a step positioning fence is disclosed in the published Canadian Patent
application 2,241,481 of Wight et al. The stepped positioning fence of Wight
has
a plurality of rigid elevated faces, or steps that extend longitudinally along
a side
of the fence in an adjacent stepped array of differing offset spacing. The
fence is
oriented to present one of the steps for contact with the lumber piece to
align the
lumber end to the corresponding offset of that step. The lumber is urged into
contact with the fence by the lateral alignment rollers resulting in alignment
of the
lumber end to the fence step offset. The stepped fence provides fixed
incremental ending settings and a positioning mechanism to ensure the board is
presented with a step suitable to obtain the desired or intended lateral
translation
of the board piece.
Another flexible trimmer position fence is disclosed in Canadian Patent
2,191,390
to Jackson, which discloses a board positioning fence comprised of a plurality
of
adjustable fence elements each staged one after the other in the downstream
direction of travel of the lumber to be positioned. The lumber is urged
against the
positioning fence by lateral alignment or ending rollers. The ending rollers
urge
the lumber laterally across the feed conveyor into contact with the successive
fence elements of the board positioning fence. When the desired lateral
positioning of the board is achieved, lift skids are engaged to remove the
lumber
from contact with the lateral urging end rollers. This arrangement has
multiple
flexible fence elements, which are adjusted to allow the board to be ended to
the
desired positioning or ending location. Once the board has been displaced
laterally to the desired position offset, skids are engaged that lift the
positioned
lumber piece away from the ending rollers.
Another arrangement to provide board lumber end positioning is disclosed in
the
Canadian patent 2,236,508 of Hannebauer et al. Hannebauer discloses a
circulating paddle positioning fence with a flexible guide track. Actuators
position
the flexible guide track, which results in corresponding positioning of a
paddle to
a desired offset or ending position.
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And yet another positioning mechanism is disclosed in the published Canadian
Patent application 2,345,872 of Jobin, for apparatus for positioning pieces of
wood for precise cutting. Jobin discloses an adjustable barrier, which is
provided
with actuators to position the barrier to the desired offset location. Various
forms
of adjustable barrier are shown including ones which have a face that remains
perpendicular to the board as well as providing for incline planes that have a
set
displacement selected by an actuator to achieve an ending or offset of the
lumber
laterally to the desired offset amount.
Summary of the Invention
The present invention provides a board positioning fence that includes
individual
paddles displaced along a continuous track loop at a spacing corresponding to
the spacing of the lumber to be positioned or ended. The paddles are laterally
displacable across the width of the track and include a brake to lock the
paddle
from lateral movement. When lateral adjustment is desired, a positioning cam
engages the paddle to release the paddle brake allowing the released paddle
travels across the track long a bearing. When the desired lateral offset
amount is
achieved, the positioning cam is disengaged from the paddle allowing the brake
to halt further lateral displacement of the lumber in the feed assembly. A
reset
cam returns the paddles to a zero position on the return travel of the track
loop.
A preferred embodiment of the invention will now be described with reference
to
the accompanying drawings in which like features of the invention are depicted
by the same reference numerals throughout the various figures of the drawings.
Brief Description of the Drawings
Figure 1 is perspective view of a preferred embodiment of the positioning
fence.
Figure 2 is an elevation view of a paddle assembly of Figure 1.
Figure 3 is an end view of the positioning fence of Figure 1.
Figure 4 is a plan view of the positioning fence of Figure 1.
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Detailed Description of the Preferred Embodiment
Figure 1 shows a perspective view of a preferred embodiment of the positioning
fence of the present invention, generally depicted by reference numeral 10.
The
positioning fences has a continuous track loop 16 extending between an opposed
set of end rollers 14 supported by a frame assembly 12. The track includes a
plurality of paddles 18 spaced along the continuous track loop 16
corresponding
to the lumber spacing of the individual board pieces that the board lumber
position fence will be used to position. Each of the paddles 18 is mounted for
lateral sliding movement across the width of the track loop along a bearing
way
20. The bearing way 20 is oriented for lateral movement of the paddle, which
is
the direction of movement that the lumber will move when positioned or ended
using the board lumber position fence. One of end rollers 14 is driven to
cause
paddles 18 to move transversely, that is in the direction of travel of the
lumber,
which is generally depicted by arrow A. Suitable means to provide drive to an
end roller includes a sprocket assembly 22 for chain coupling to a torque
source,
such as a drive motor or the lumber transport system that the position fence
operates with or other equipment in the saw mill. To construct the continuos
loop
track 16, each end of bearing way 20 is coupled to a flexible web 24 extending
between each of the end rollers 14. Flexible web 24 is constructed from a belt
or
a chain. In this manner, the paddles 18 of the continuous track 16 are driven
in
the direction of arrow A.
31
Figure 2 shows a side elevation view of a preferred embodiment of a paddle
assembly constructed in accordance with the principles of the invention,
generally
depicted by reference numeral 18. The paddle assembly 18 has a bearing 26
that is slidably mounted on bearing way 20. The sliding engagement between
bearing 26 and bearing way 20 permits lateral movement of the paddle assembly
18 along bearing way 20 in the directions shown by double headed arrow B. A
paddle.lumber seat 28 provides a surface on which the lumber piece to be
positioned rests. A pivot arm 30 interconnects the paddle lumber seat 28 with
bearing 26 at pivot 32. A brake 34 prevents movement of the paddle assembly
18 along bearing way 20 when a lumber piece rests on the paddle lumber seat
28. A force "F" applied to the paddle lumber seat 28 and/or a biasing means
33,
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such as a spring, rotates pivot arm 30 around pivot 32 urging brake 34 into
contact with bearing way 20 thus preventing sliding lateral movement of the
paddle assembly 18 along bearing way 20. Brake 34 is constructed from a
suitable friction material such as for example polyurethane.
Each paddle assembly includes cam followers to effect movement and
positioning of the paddle assembly 18 along bearing way 20. A positioning cam
follower 36 is used to urge the paddle assembly 18 in a right-to-left
direction
along bearing way 20 and a reset cam follower 38 is used to urge paddle
assembly 18 in the opposite direction, that is, in a left-to-right direction.
Engagement of cam followers 36 or 38 releases the brake 34. For example,
when a cam contacts the positioning cam follower 36 in the direction of arrow
"P",
pivot arm 30 rotates to release brake 34 allowing the cam to move the paddle
assembly to the left. Similarly, when a cam contacts the reset cam follower 38
in
the direction of arrow "R", pivot arm 30 rotates to release brake 34 allowing
the
cam to move the paddle assembly to the right. Consequently cam followers 36
and 38 are used to position the paddle assembly 18 at a desired location on
bearing way 20.
Figure 3 is an end view of a preferred embodiment of the board lumber position
fence assembly 10. A reset or zeroing cam 40 is coupled to the frame assembly
12 of the board lumber position fence. Reset cam 40 is provided for contact
with
the reset cam follower 38 of each paddle assembly and is used to urge each
successive paddle assembly 18 that passes along it back into a zero or reset
position. The zero or reset position is the position of the paddle assembly in
the
right most location along each respective bearing way 20. When the paddle
assembly is in the zero or reset position it can traverse in a right-to-left
fashion to
the other end of the bearing way as required to end or provide a lateral
position to
a board lumber piece.
A positioning cam 41 is provided on the opposite paddle travel side of the
track,
that is in the upper area of the board lumber position fence. The positioning
cam
is moveable between a released position or a locked position. When the
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positioning cam segment is in the released position, it is oriented to engage
the
lower cam follower 36 of each successive paddle assembly 18 passing along it.
When the positioning cam 41 is in the released position, it comes into contact
with the positioning cam follower 36 of a paddle assembly 18 and the paddle
assembly is freed to move in a right-to-left direction along bearing way 20.
In
operation of the lumber positioning fence, a lumber piece 46 is seated on the
paddle lumber seat 28 and is urged in the direction of arrow "F". Thus when
the
positioning cam 41 is oriented into released position as shown in Figure 3, it
comes in contact with the position cam follower 36 and the paddle assembly 18
is
freed to move in a right-to-left direction. Consequently, lumber piece 46 will
then
move in the direction of arrow "F" until the positioning cam 41 is oriented
into a
locked position, which causes the paddle assembly 18 to lock in that lateral
position or location. Thus, when the desired offset or lateral displacement of
the
lumber piece 46 seated on paddle assembly 18 is achieved, the positioning cam
41 is actuated to release it from contact with lower cam follower 36, thereby
causing the paddle assembly 18 to lock in that location.
Figure 4 shows a top plan view of the board lumber position fence giving
another
view of the cam assemblies in accordance with the present invention. A top
plan
view of the zeroing cam 40 shows it is positioned at an angle to the direction
of
travel of the paddles 18 mounted on the continuous track loopl6. As the
paddles
18 travel past the zeroing cam 40, they are urged to return to the zero
position,
which all paddles in the drawing are shown in with the exception of displaced
or
offset paddle 48. Also visible in this drawing is the positioning cam 41,
which is
set at an angle to the direction of travel of the paddles 18. The positioning
cam is
orientable between a released position, which effects lateral movement of each
paddle passing therealong, and a locked position, where no lateral movement of
a passing paddle occurs.
Preferably, the positioning cam 41 is constructed from a plurality of
positioning
cam segments, where each segment being orientable between a released
position 42 and a locked position 52. An actuator 50 orients a corresponding
respective positioning cam segment between the released orientation 42 and the
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locked orientation 52. The positioning cam segments 42 are all oriented in a
released orientation or position 42, with the exception of positioning cam
segment
52, which is in the locked orientation or position. The positioning cam is
preferably provided in segments each with its own respective actuator to
facilitate
separate control of each individual paddle even with a shallow cam angle and
close spacing of the paddles 18 along track 16. Therefore, cam segments on the
positioning cam permit gradual lateral adjustment of the lumber pieces, even
with
a close spacing of the paddle/lumber piece along the length of the continuos
track loop 16.
The locked orientation of cam segment 52 illustrates operation of the
positioning
fence. As the displaced or offset paddle 48 passed along the positioning cam
41,
contact of that paddle's lower cam follower with the segments of the
positioning
cam allowed the board lumber piece 46 (shown in dotted outline form) to move
laterally and be positioned at an off set from the zero position. When the
board
lumber piece reaches the desired offset amount, the positioning cam segment
was actuated away from contact with the cam follower of the associated paddle,
causing the paddle brake to lock, thereby halting further lateral displacement
of
the lumber piece 46.
Now that the invention has been described numerous variations, substitutions
and equivalents will come to the mind of those skilled in the art. The
invention, is
not however, limited to the specific embodiments described herein with
reference
to the attached drawings, but rather, the scope of the invention is defined by
the
claims appended hereto.
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