Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02532386 2006-O1-06
CONVEYOR SYSTEM
Field of the Invention
This invention relates to the field of devices far positioning a worlcpiece in
a
sawmill, and more particularly, it relates to a system for positioning a
warkpiece on. a sharp chain
conveyor system.
Back,~roimd of the Invention
is
A workpiece, such as a log or a cant, havuig a maximum of 30 inches in
diameter is
typically transported on a sharp chain conveyor system. This is also typically
known as a "Single
Length Infeed" (SLI) system. Such a sharp chain conveyor system includes a
conveyor chain
having shazp teeth which extend vertically upwards from the conveyor chain to
fnmly engage and
secure onto the surface of the workpiece. A plurality of parallel spaced apart
turning rolls are
perpendicular to the direction of flow of the sharp chain conveyor. The
turning rolls may be
moved vertically to permit an operator to manually rotate the workpiece about
its longitudinal axis
to a position determined by the operator to be the optimal position. The
turning rolls are then
lowered so that the warkpiece re-engages the sharp teeth of the sharp chain
conveyor for transport
2 0 of the warkpiece downstream through a scanner. An optimizer then
determines an optimal cutting
solution for the warkpiece to produce the highest value or yield of lumber.
The manual rotation of the worlcpiece is a slow and time consuming process as
the
operator requires time to assess and position the workpiece in tile most
favourable position.
2 5 Furthernlare, such process may significantly reduce lumber recovery since
the positioning of the
workpiece by the operator is subject to human error in judgment. On ce floe
operator lowers th.e
workpiece back onto the sharp chain conveyor and the warkpieee is transported
downstream past
the turning rolls, there is no means for repositioning the workpiece. If the
operator incorrectly
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CA 02532386 2006-O1-06
positioned the workpiece such error may compromise the optimal cutting
solution determined by
the scanner and optimizer, thereby reducing lumber recovery and there is no
means of readjusting
to correct the position of the workpiece.
To address the shortcomings of the SLI system, a "Double Length Infeed" (DLI)
system has been developed to eliminate the manual rotation of the workpiece.
In place of the
operator and fuming rolls, the DLI system uses a scanner and optimizer to
determine the optimal
position of the workpiece and simultaneously, a rotating conveyor rotates the
workpiece into such
optimized position, thereby eliminating the time required to visually assess
and manually rotate the
workpiece. The workpiece is then fed onto a second conveyor where it passes
through a second
scanner and optimizer to determine the optimized cutting solution far the
workpiece. On such a
second conveyor, the workpieee may be further displaced laterally and
angularly relative to its
centreline so that the workpiece may be optimally positioned fox processing in
accordance with the
optimized cutting solution. Once the workpiece is optimally positioned, it is
fed onto a third.
conveyor, which is a sharp chain conveyor, to be transported to the primary
breakdown sawing
machines.
Although the DLI system is capable of positioning the workpiece in its
optimized
position, the worlcpiece may be subsequently displaced from its position as
the workpiece is
2 0 transported towards the primary breakdown machines. For example, hold-down
rolls which ride
along the upper surface of the workpiece to bald the workpiece in place on the
conveyor may
engage protruding knots or other superficial irregularities on the warkpiece
surface. Contact with
such rough surfaces between the hold-down rolls and protruding knots may
result in a
displacement of the workpiece from its optimized position.
Furthermore, the workpiece may also be displaced when the worlcpiece is
transported between the multiple conveyors. Distances between successive
conveyors may span
up to 4~ inches and the workpiece may be transported butt first from conveyor
to conveyor. Such
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a butt end, which is typically flared, may initially displace vertical.l.y
downwards into the
unsupported space defined by the span distance and be abruptly raised back
onto the conveyor by
engaging the succeeding conveyor, thereby disrupting the optimized position of
the workpiece.
Vertical rolls positioned between the conveyors to grip the workpiece and
prevent it from
displacing vertically into the void may be provided. However, such rolls may
cause undesired
movement of the workpiece as well. In addition, because of the length of the
DLI system,
substantial physical space is required to accommodate such machinery, thereby
increasing the cost
of production.
~ 0 Accordingly, there is required a shorter conveyor system capable of
positioning and
maintaining the optimized position of a workpiece as the workpiece is being
transported towards
the primary breakdown machines.
Summary of the Invention
It is an object of the invention to provide a continuous sharp chain conveyor
system
for transposing a workpiece such that span distances between successive
conveyors are
eliminated.
2 0 It is another object of the invention to provide a sharp chain. conveyor
system
having a single conveyor to reduce the length of the system.
It is another object of the invention to provide a means to elevate the
workpiece
from the sharp chain conveyor such that the position of the workpiece may be
adjusted at any time
2 5 while the workpiece is transported down the sharp chain conveyor system.
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It is a further object of the invention to provide a continuous means to
rotate the
workpiece such that the optimized position of the workpiece may be maintained
while the
workpiece is transported down the sharp chain conveyor system.
The present invention includes or cooperates with a sharp chain conveyor
system
which includes a sharp chain adapted to engage a first surface of the
workpiece_ A first and a
second skid is positionable in parallel alignment with the sharp chain. The
first and the second
skid is adapted to displace the workpiece between a lowered first and an
elevated second position.
A plurality of rotatable positioning drive rolls are positionable along the
sharp chain. The plurality
of rotatable positioning drive rolls are adapted to rotate the workpiece when
the worlcpiece is
displaced by the first and the second skid into the second position. The
system may also include a
plurality of hold-down rolls pivotally coupled with a frame such that the
plurality of hold-down
rolls may engage a second surface of the workpiece to maintain the workpiece
on the sharp chain
by exerting pressure on the workpiece.
The sharp chain may be a continuous chain having a plurality of teeth for
engaging
the workpiece. The first and second skids may be disposed on either side of
the sharp chain such
that the sl2arp chain is interposed between the first and the second skids. To
displace the
workpieee to the first position, the first and second skids displace
vertically downwards relative to
2 0 the sharp chain such that the workpiece engages the sharp chain. To
displace the workpiece to the
second position, the first and second skids displace vertically upwards
relative to the sharp chain
such that the warkpiece is elevated and disengages from the sharp chain.
A first wheel may be disposed between a first end of the first and second skid
and a
2 5 second wheel may be disposed between a second end of the first and the
second skid. A first
through-shaft journals through the first and second skid and the first wheel
at a first end and a
second through-shaft journals through the first and second skid and the second
wheel at a second
end. The first and said second wheels are eccentrically mounted on the first
and second through-
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shafts. A member couples the first through-shaft with the second through-shaft
such that when a
first actuating means rotates the first through-shaft, the member transfers
rotationa.i movement of
the first through-shaft to rotate the second through-shaft. Such rotational
movement of the first
through-shaft and the second through-shaft causes the fast and second wheel to
uniformly displace
the ftrst and second skid between the first position and the second position
by the caaaa action of the
eccentric wheels bearing down against a rigid bearing surface thereby forcing
the skids upwardly.
fairs of the rotatable positioning drive rolls are positionable along the
sharp chain
such that one rotatable positioning dxive roll from each pair of rotatable
positioning drive rolls is
positionable on each side of the sharp chain. The rotatable positioning drive
rolls are pivotally
coupled with the frame such that the pairs of rotatable positioning drive
rolls may displace laterally
towards and away from a longitudinal centreline of the workpiece and displace
angularly relative
to the longitudinal centreline of the workpiece. A second actuating means may
laterally displace
the rotatable positioning drive to engage the workpiece such that the
actuating means may
cooperatively move the rotatable positioning drive rolls to displace the
workpieee laterally relative
to tlae longitudinal centreline of the sharp chain (an offset/slew).
Furthermore, second actuating
means may also angularly displace one rotalable positioning drive roll of each
pair of rotatable
positioning drive rolls such that the actuating means may independently move
each of the rotatabl a
positioning drive rolls to displace the workpiece angularly relative to the
longitudinal centreline of
2 0 the sharp chain (a skew/slew).
The sharp chain conveyor system cooperates with a scanner and an optimizer
processing data from the scanner. The optimizer determines an optimized
position for the
workpiece. The optimizer is in transmittable communication with the second
actuating means to
2 5 control the pairs of rotatable positioning drive rolls to position the
workpieee in the optimized
position. The optimizer may also be in transmittable communication with the
first actuating
means to control the first and second skids to elevate the workpiece to enable
the pairs of rotatable
positioning drive rolls to position the workpiece in the optimized position.
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Brief Description of the Drawings
Various other objects, features and attendant advantages of the present
invention
will become fully appreciated as the same becomes better understood when
considered in
conjunction with the accompanying drawings, in which like reference characters
designate the
same or similar parts throughout the several views, and wherein:
Figure l, is a plan view of a sharp chain conveyor system according to the
present
invention.
Figure 2 is a side elevation of the sharp chain conveyor system of Figure 1.
Figure 3 is an enlarged side elevation view of the sharp chain conveyor system
of
Figure 2.
Figure 4 is a section view along Iine 4-4 in Figure 3.
Figure 5 is an elevation view along Iine 5-5 in Figure 4.
Figure 6 is a sectional view taken on Iine 6-6 in Figure 4.
Figure 7 is a sectional view taken on line 7-7in Figure 6.
2 5 Figure 8a is a plan view of a pair of rotatable positioning drive rolls
displacing tlae
workpi.ece laterally of the flow direction.
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Figure 8b is a plan view of a pair of rotatable positioning drive rolls
displacing the
workpiece laterally to the right of the longitudinal centreline of the sharp
chain as viewed in the
flow direction.
Figure 8c is a plan view of a pair of rotatable positioning drive rolls
displacing the
workpiece laterally to the left of the longitudinal centreline of the sharp
chain as viewed in the
flow du~ection.
Figure 9 is an exploded view of the first and second skid as shown in .Figure
4.
Detailed Desc~tion of Embodiments of the Invention
With reference to Figures 1 to 9, wherein similar characters of reference
denote
corresponding parts in each view, the sharp chain conveyor system 10 according
to the present
invention includes a conveyor such as sharp chain 15 which engages the surface
of a worlcpiece
18. A first and a second skid 25 and 27 mounted to conveyor system 10 are
configured to raise
and lower workpiece 18 relative to sharp chain 15. A plurality of rotatable
positioning drive rolls
30 mounted on a frame 35 rotates workpiece 18 into an optimized position.
2 0 Preferably, sharp chain 15 is a continuous steel chain. Teeth on sharp
chain 15
enable sharp chain 15 to secure and engage workpiece 18 for transporting
workpiece 18 along
conveyor system 10 towards a primary breakdown machine, such as a headsaw (not
shown).
Sharp chain 15 may be mounted in one embodiment at one end on a drive sprocket
32, which is
driven by suitable means lrnown in the art to transport a workpiece 18 along
conveyor system 10.
2 5 The other end of the sharp chain may be mounted on an idler sprocket (not
shown).
Sharp chain conveyor system 10 may further comprise a plurality of hold-down
rolls 20 for maintaining warkpieee 18 an shazp chain 15. Typically, hold-down
rolls 20 are
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pivotally mounted to a frame 35 to enable hold-down rolls 20 to move towards
and away from
workpiece 18. Hold-dawn rolls 20 may be actuated by any suitable means such as
pneumatically
actuated cylinders 40 to engage hold-down rolls 20 with a surface of workpiece
18. Hold-dawn
rolls 20 are usually positioned above workpiece 18 such that they may firmly
contact the upper
surface of workpiece 18 to maintain workpiece 18 on sharp chain 1 S by way of
downward
pressure, as seen more clearly in Figure 3.
First and second skids 2S and 27 are mounted in parallel alignment, one on
either
side of sharp chain I S along the entire length of sharp chain conveyor system
10. First and second.
2 0 skids 2S and 27 are simultaneously vertically displaceable in direction A
upwards and downwards
in direction B between a lowered first position 28 (shown in dotted outline in
Figure 6) and an
elevated second position 29, as seen in saiid outline in Figure 6. When first
and second skids 25
and 27 are in lowered first position 28, first and second skids 25 and 27 are
positioned below
workpiece 1$ such that workpiece 18 engages sharp chain 15, therebypermitting
sharp chain 15 to
1 ~ engage the lower surface of workpiece 18. When first and second skids are
in elevated second
position 29, first and second skids 25 and 27 are positioned above sharp chain
I 5 thereby raising
workpiece 18 above sharp chain 15 to permit positioning of workpiece 18.
In an embodiment of the invention, at a first end of first and second slci.ds
25 and
2 0 27, a .first through-shaft 45 is journalled through first and second skids
25 and 27. First through-
shaft 45 is also journalled through a first wheel 46 disposed between first
and second skids 25 and
27 such that .first wheel 46 is eccentrically mounted on first through-shaft
45. Similarly, at a
second end of first and second skids 25 and 27, a second through-shaft 47 is
journalled through
first and second skids 25 and 27. Second through-shaft 47 is also journalled
through a second
2 S wheel 48 disposed between first and second skids 25 and 27 such that
second wheel 48 is
eccentrically mounted on second through-shaft 47. Thus rotating first and
second through-shafts
45 and 47 raises or lowers skids 25 and 27 as hereinafter better described. Ta
vertically displace
fast and second skids 25 and 27 between lowered fast position 28 and elevated
second position
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29, an actuator, such as a pneumatic cylinder 52 causes first through-shaft45
to rotate. Preferably,
pneumatic cylinder 52 is coupled with frame 35 and an extendible arm 50 of
pneumatic cylinder
52 is pivotably mounted to an end of first lever 53. First lever 53 is mounted
on a first end of first
through-shaft 45 such that when pneumatic cylinder 52 is actuated, causing
extendible arm 50 to
extend or retract, ftrst lever 53 as seen in Figure 9 causes first through-
shaft 45 to rotate in a
clockwise or counter-clockwise direction.
As seen in Figures 5 and 9, rotation of first through-shaft 45 also rotates
second
through-shaft 47 by driving member 55. At a first end, member 55 is pivotably
coupled with a
l 4 first end of a second lever 57 and at second end, member 55 is pivotably
coupled with a first end
of third lever 59. A second end of second lever 57 is mounted on a second end
of first tl~rough-
shaft 45 and a second end of third lever 59 is mounted on an. end of second
through-shaft 47 such
that when pneumatic cylinder 52 is actuated, first lever 53 causes first
through.-shaft 45 to rotate,
thereby displacing second lever 57 mounted on the second end of first through-
shaft 45. Second
25 lever 57 converts the rotary motion of first through-shaft 45 into
reciprocating motion, thereby
driving member 55 to displace third lever 59. Member 55 therefore transfers
rotational movement
of first through-shaft 45 to rotate second through-shaft 47 by displacing
third Lever 59, which
causes second through-shaft 47 to rotate, resulting in the uniform vertical
displacement of first and
second skids 25 and 27 presuming that wheels 46 and 48 are uniform.Iy
eccentrically mounted on
2 0 shafts 45 and 47. More particularly, as seen in Figure 9, extension of
extendible arm 50 causes
first lever 53 to displace, causing first through-shaft 45 to rotate in a
clockwise direction C.
Rotation of first through-shaft 45 displaces second Lever 57, thereby driving
member 55 and
causing third lever 59 to displace and rotate second through-shaft 47.
Rotation of first-through
shaft 45 and second through-shaft 47 causes first wheel 46 and second wheel 48
to rotate in
2 5 direction D. As first ulheel 46 and second wheel 48 rotate in direction D,
fast wheel 46 and
second wheel 48 exerts downward pressure on frame member 58 of frame 35, best
seen in Figure
9, thereby elevating f rst through-shaft 45 and second through-shaft 47,
causing first and second
skids 25 and 27 to vertically displace from lowered first position 28 to
elevated second position
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29. Retraction of extendible arm 50 therefore causes first lever 53, second
lever S7, and third lever
59 to rotate first through-shaft 45 and second through-shaft 47 in a counter-
clockwise direction,
thereby causing first wheel 46 and second wheel 48 to rotate oppasitely to
direction D, thereby
lowering first through-shaft 45 and second through-shaft 47 such that first
and second skids 25 and
27 may vertically displace from elevated second position 29 to lowered first
position 28.
Preferably, pairs of rotatable positioning drive rolls 30 are positionable
along the
length of sharp chain conveyor system 10 such that one positioning drive roll
30 of each pair is
positioned on each side of sharp chain I 5, as best seen in Figures 8a to 8c.
Although illustrated as
having a spiked outer surface, it is understood that the outer surface of
drive rolls 30 may also be
fluted or otherwise adapted to grip the outer surface of warkpiece 18,
preferably without marring
of the workpiece surface. Typically, rotatable positioning drive rolls 30 are
vertically oriented and
pivotally coupled to frame 35 to assist in both the transport and positioning
of workpiece 18. To
laterally and angularly displace workpiece 18 relative to the longitudinal
centreline of sharp chain
15, ratatable positioning drive rolls 30 may be selectively brought into
contact with the surface of
workpiece 18. Rotatable positioning drive rolls 30 may cooperate as a pair to
move workpiece 18
laterally towards and away from the longitudinal centreline ofworkpiece 18, as
shown by arrow C.
Each rotafiable positioning drive roll 30a and 30b of each pair of rotatable
positioning drive rolls
30 may also independently move angulariy towards and away from the
longitudinal centreline of
2 d workpiece I8, as shown by avows D and E. To control the movement of
rotatable positioning
drive rolls 30, actuator means, such as a hydraulic cylinder 65 may be
provided to operate each
pair of rotatable positioning drive rolls 30.
To position warkpiece 18, pneumatic cylinder 52 actuates rotation of first and
2 5 second through-shafts 45 and 47 in a first direction, causing skids 25 and
27 to vertically displace
upwards to elevated second position 29. V~orkpiece 18 is thereby elevated and
disengages from
sharp chain 15 to be rotated by rotatable positioning drive rolls 30.
fTydraulic cylinder 65 moves
CA 02532386 2006-O1-06
rotatable positioning drive rolls 30 such that rotatable positioning drive
rolls 30 engage the surface
of workpiece I 8.
As seen in Figure 8a, if the optimized position for workpiece I8 is to
position
workpiece I8 such that the longitudinal centreline of workpiece I8 may be
laterally displaced
relative to the longitudinal centreline A of sharp chain I S, hydraulic
cylinder 6S cooperatively
moves rotatable positioning drive rolls 30 in the direction of arrow C to
position workpiece 18.
Rotatable positioning drive rolls 30 may be positioned equidistant from the
longitudinal centreline
A of sharp chain L 5 such that the longitudinal centreline of workpiece 18 may
be positioned
generally in parallel with the centreline A of sharp chain I S.
As seen iaa Figure 8b, if the optimized position For warlcpiece I8 is to
angularly
displace workpiece 18 such that the longitudinal centreline of workpiece 18 is
skewed to the right
relative to longitudinal centreline A of sharp chain 1 S, hydraulic cylinder
6S independently moves
one of the rotatable positioning drive rolls 30 to angularly/Iaterally
position workpiece I8
according to the optimized position. To skew or angularly position workpiece
18 to the right of
the longitudinal centreline A of sharp chain 1 S, hydraulic cylinder 65
independently moves
rotatable positioning drive rolls 30a in the direction of arrow D to urge
workpiece 18 to the right
and hydraulic cylinder 6S extends to independently move positioning drive roll
30b to cooperate
2 0 with the angular displacement of workpiece I8 wherein the pivot shaft may
be referenced as a
datum.
As seen in Figure 8c, if the optimized position for workpiece I8 is to
angularly
displace workpiece I 8 such that the longitudinal centreline of workpiece 18
is skewed to the left
2 5 relative to longitudinal cenfireline A of sharp chain 1 S, hydraulic
cylinder 6S independently moves
rotatable positioning drive rolls 30 to angularly/laterally position workpiece
18 according to the
optix~~zized position. To skew ar anguLarly position workpiece I8 to the Left
of the longitudinal
centreline A of sharp chain I 5, hydraulic cylinder 6S independently moves
rotatable positioning
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drive roll 30b in the direction of arrow E to urge worlcpiece I 8 to the Ieft
and hydraulic cylinder 6S
retracts to independently move rotatable positioning drive roll 30a to
cooperate with the angular
displacement of warl~piece I 8.
Once workpiece I8 is in the optimized position, pneumatic cylinder 52 actuates
rotation of first and second through-shafts ~5 and 47 in a second direction,
causing skids 25 and 2'7
to vertically displace downWardS to lowered first position 28. Pneumatic
cylinder 65 moves
rotatahle positioning drive rolls 30 such that rotatable positioning drive
rolls 30 disengage from
the curved surface of workpiece 18 and workpiece I 8 re-engages with the teeth
of sharp chain 15
in the optimized position. Hold-down rolls 20 engage workpiece I8 to hold
worlcpiece 18 on
sharp chain 15 by way of downward pressure.
The present invention is intended to be included within a larger lumber
processing
system for example as used in sawmills. It is contemplated and within the
scope of the present
invention that workpiece I 8 may be processed prior to being fed onto sharp
chain conveyor system
10. For example, rotatabl.e positioning drive rolls 30 may displace in
response to a signal sent
from a scanner and optimizer which scanned and optimized workpiece 18 prior to
workpiece 18
being placed on sharp chain conveyor 10. Such signal is transmitted by
conventional means such
as a conductor cable from the scanner and optimizer to be received by motion
controllers which
2 0 control hydraulic cylinders 65 to independently or cooperatively actuate
rotatable positioung drive
rolls 3a to position workpiece 18 according to the optimized position
determined by the scanner
and optimizer. Preferably, the scanner and optimizer fornls a part of sharp
chain conveyor system
14.
2 5 Moreover, in interpreting both the specification and the claims, all terms
should be
interpreted in the broadest possible manner consistent with the context. In
particular, the terms
"comprises" and "comprising" should be interpreted as referring to elements,
components, or steps
in a non-exclusive manner, indicating that the referenced elements,
components, or steps tnay be
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CA 02532386 2006-O1-06
present, or utilized, or combined with other elements, components, or steps
that are not expressly
referenced.
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 thexeo~ Accordingly, the scope
ofthe invention is to be
construed in accordance with the substance defined by the following claims.
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