Note: Descriptions are shown in the official language in which they were submitted.
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LATH OR STICK PLACING APPARATUS
FIELD OF THE INVENTION
The present invention relates to machinery for the lumber industry and more
particularly concerns an apparatus and a method for placing laths or sticks on
tiers
of lumber.
BACKGROUND OF THE INVENTION
Finished lumber is commonly stacked for drying and/or shipping purposes.
Sticks
io or "spacing sticks" are commonly used to hold apart successive tiers of
lumber
while drying, while in the context of lumber packaging, laths are inserted
between
layers of lumber transversally to the length of the wood, in order to preserve
the
integrity of a package of lumber during and after shipment. Although laths and
sticks usually have different characteristics related to their particular use,
they both
are generally thin strips made of wood, typically, or another appropriate
material
such as cardboard or the like.
The placement of laths or sticks on a tier of lumber is an operation which is
usually
automated in modern sawmills, and the need for an ever increasing production
speed requires that the speed of this operation be optimized.
In the prior art, many machines have been devised for placing laths or sticks
onto
stacks of lumber one by one. Examples of such machines are for example shown
in US patents nos. 4,264,253 (KENNISON); 4, 801,233 (RITOLA); 5,636,965
(NEWNES et al.); 6,655,902 (DUBE et al.); and 6,439,829 (JOHNSON) as well as
in Canadian patents nos. 2,237,951 (BARON et al.) and 2,200,656 (NEWNES et
al.).
Typical lath laying machines include a magazine holding a stack of laths and a
mechanism picking-up the bottom-most lath from the magazine and bringing it to
its destination onto the tiered lumber, where it is generally placed
transversally to
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the lumber before the next layer of lumber is added to the stack. In these
prior art
lath placers, the laths may be stacked in the magazine along their length
either
flatly, i.e. with the flat faces of consecutive laths touching or upright,
i.e. with the
sides of consecutive laths touching.
When using a magazine filled with laths stacked upright, it is necessary to
turn the
laths on their flat sides before placing them of the tiered lumber. In known
lath
placers of this type, the bottom-most lath of the stack is first received
upright on a
conveyor where it is pushed laterally towards a pick-up location, to be
gripped by
io pincers or the like. A turning mechanism rotates the pincers by about 90
degrees,
thereby turning the lath held within on its flat side. The turned lath is then
lowered
towards the tier of lumber and laid thereon by releasing the pincers. A
drawback of
lath placers of this type is that the placing of a given lath requires several
steps,
which each require time and therefore slow down the process. In addition, the
mechanism controlling the pincers has to be fairly complex as it must both
rotate
to pivot the lath, and move vertically to bring the lath to its destination.
There is therefore a need for an improved lath or stick placer which
alleviates at
least some of the drawbacks of the prior art.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a lath or stick placing
apparatus of
the type using a magazine holding a stack of laths piled upright, which is
more
efficient than prior art machines described above.
It is also an object of the present invention to provide an efficient method
of
placing laths or sticks onto tiered lumber.
In accordance with a first aspect of the present invention, there is therefore
provided a placing apparatus for placing elongated articles, such as laths or
sticks,
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onto a tiered lumber surface. Each elongated article has an upright
orientation and
a flat orientation along its length.
The placing apparatus first includes a magazine for holding a stack of the
elongated articles stacked in their upright orientation. The magazine has a
bottom
dispensing opening for successively dispensing the elongated articles, each
thereby successively defining a dispensed elongated article.
The placing apparatus also includes a positioning mechanism for receiving the
io dispensed elongated article in the upright orientation, and translating it
from
beneath the magazine to a pick-up location. The positioning mechanism further
pushes on the dispensed elongated article to pivot it in the flat orientation
as it is
being translated.
Finally, the placing apparatus also includes a gripping mechanism adjacent to
the
magazine. The gripping mechanism is selectively movable between a retracted
position for gripping the dispensed elongated article at the pick-up location,
and an
extended position for releasing the dispensed elongated article onto the
tiered
lumber surface.
According to another object of the present invention, there is also provided a
method for placing elongated articles onto a tiered lumber surface. Each
elongated
article has an upright orientation and a flat orientation along a length
thereof. The
method includes the following steps:
a) holding a stack of the elongated articles stacked in their upright
orientation;
b) successively dispensing the elongated articles, each thereby successively
defining a dispensed elongated article;
c) receiving the dispensed elongated article in the upright orientation and
translating the same to a pick-up location, pushing on the dispensed
elongated article to pivot it in the flat orientation as it is being
translated;
d) gripping the dispensed elongated article at the pick-up location;
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e) moving the gripped dispensed elongated article towards the tiered lumber
surface; and
f) releasing said dispensed elongated article onto the tiered lumber surface.
Other features of the present invention will be better understood upon reading
of
preferred embodiments thereof with reference to the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FfGs. 1 to 9 are side views of a lath placing apparatus according to a first
io embodiment of the invention, showing the sequence of steps for transferring
a lath
from a magazine towards and onto a tiered lumber surface, in which:
FIG. 1 shows a bottom-most lath from the magazine received in the upright
orientation by the positioning mechanism and starting to be pushed toward the
pick-up location;
FIG. 2 shows the lath still being pushed towards the pick-up location and
being
simultaneously turned from the upright to the flat orientation;
2o FIG. 3 shows the lath having been turned in the flat orientation and still
supporting
the next bottom-most lath in the magazine;
FIG. 4 shows the lath on the positioning mechanism still being pushed towards
the
pick-up location, the next bottom-most lath being supported by the abutment
member;
FIG. 5 shows the lath at the pick-up position beneath the gripping mechanism
and
starting to be picked-up by the latter;
3o FIG. 6 shows the lath held by the gripping mechanism while the support
plate is
being retracted back to its initial position;
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FIG. 7 shows the picked-up lath starting to be lowered towards the tier of
lumber
and the next bottom-most lath having been lowered by gravity on the support
plate
of the pushing mechanism;
5 FIG. 8 shows the gripping mechanism in its extended position, and releasing
the
picked-up lath on the tier of lumber; and
FIG. 9 shows the gripping mechanism returning back to its retracted position
to be
ready for picking up the next lath.
FIG. 10 is a perspective view of a lath.
FIGs. 11 to 19 are side views of a lath placing apparatus according to a
second
embodiment of the invention, also showing the sequence of steps for
transferring a
lath from the magazine towards and onto a tiered lumber surface, in which:
FIG. 11 shows a bottom-most lath from the magazine received in the upright
orientation by the positioning mechanism;
2o FIG. 12 shows the lath starting to be pushed toward the pick-up location
and being
simultaneously turned from the upright to the flat orientation while the next
bottom-
most lath is retained by the retractable holder;
FIG. 13 shows the lath further in the process of being turned in the flat
orientation;
FIG. 14 shows the lath on the positioning mechanism in the flat orientation;
FIG. 15 shows the lath on the positioning mechanism in the flat orientation
being
pushed towards the pick-up location;
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FIG. 16 shows the lath at the pick-up position beneath the gripping mechanism
and starting to be picked-up by the latter;
FIG. 17 shows the lath held by the gripping mechanism;
FIG. 18 shows the lath still being held by the gripping mechanism while the
support plate is being retracted back to its initial position;
FIG. 19 shows the support plate fully retracted to its starting position and
receiving
io the next lath in the magazine.
While the invention will be described in conjunction with an example
embodiment,
it will be understood that it is not intended to limit the scope of the
invention to
such embodiment. On the contrary, it is intended to cover all alternatives,
modifications and equivalents as may be included as defined by the appended
claims.
DESCRIPTION OF PREFERRED EMBODIMENTS
In the following description, similar features in the drawings have been given
similar reference numerals and in order to lighten the figures, some elements
are
not referred to in some figures if they were already identified in a preceding
figure.
The present invention concerns apparatuses and a method for placing elongated
article on a tiered lumber surface. The expression "elongated article" is used
herein to refer to laths, spacing sticks, or any object of the kind one may
wish to
place between tiers of lumber. As such, the elongated article is preferably
made of
wood but may also be made of any other appropriate material such as plastic,
metal or cardboard.
In the description of preferred embodiments below, the present invention will
be
applied to the placement of laths in particular and the "elongated articles"
will be
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referred to as laths to simplify the reading of the present description. One
skilled in
the art will however understand, as explained above, that the principles of
the
invention could equally be applied to stick placers of other machines placing
similar articles.
Referring to FIG. 10, a typical lath 2 is shown. A lath 2 generally has a
rectangular
cross-section, and therefore has two opposite flat surfaces 7 and two opposite
side surfaces 8. Preferably, a lath is placed on the tiered lumber on one of
its flat
surfaces 7, which is referred to hereinafter as "the flat orientation". By
contrast,
to positioning the lath on one of its side surfaces 8 will be referred to as
"the upright
orientation". It will be understood that the laths need not have a perfectly
rectangular cross-section and that other shapes could be considered.
Referring to FIGs. 1 to 9, a first embodiment of a placing apparatus 10 for
placing
ts laths 2 on a tiered lumber surface 6, and its operation, is illustrated.
The tiered
lumber surface 6 receiving the laths is preferably embodied by successive
layers
of lumber 4 being packaged for transport, or for drying in the case of sticks.
In
practice, the laths 2 are disposed transversally to the length of the tiered
lumber 4,
but the actual longitudinal orientation of the laths 2 once placed on the
lumber 4 is
20 irrelevant to the present invention. The present invention could be used to
place
one or more lath(s) 2 per lumber tier, as well as for placing laths 2 at each
lumber
tier or only after a predetermined number of layers in a given package.
The placing apparatus 10 first includes a magazine 12 for holding a stack 14
of
25 laths stacked in their upright orientation, that is, on one of their side
surfaces as
explained above. Although the magazine 12 is shown as strictly vertical in the
accompanying drawings, it could be slightly slanted without departing from the
scope of the present invention. Similarly, the laths 2 could be stored in the
magazine 12 at a slight angle with respect to the vertical without departing
from
30 the meaning of "upright orientation" as it is understood herein. The
magazine 12
can be formed by any structure adapted to hold more than one lath 2 in the
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stacking arrangement described above. It can have a width sufficient to
provide
some horizontal play for the laths 2 inside, as long as they remain stacked in
their
upright orientation. It will be noted that the laths need not be all of the
same size
and width, as will be clear from the description of another embodiment further
s below. The magazine has a bottom dispensing opening 13 for dispensing the
laths
2 successively, that is, one by one. The laths 2 are therefore gravity-fed out
of the
magazine 12. A lath having been dispensed from the magazine 12 will be
referred
to as a "dispensed lath 2a".
io Each dispensed lath 2a is received and moved by a positioning mechanism 20.
The positioning mechanism receives the dispensed lath 2a in the upright
orientation, and translates it from beneath the magazine 12 to a pick-up
location
28, as will be explained further below. Advantageously, the positioning
mechanism
20 also pushes on the dispensed lath 2a to pivot it in the flat orientation as
it is
15 being translated.
Preferably, the positioning mechanism 20 includes a support plate 21 movable
along a generally horizontal course. The support plate preferably has a lower
landing 22, on which is received the dispensed lath 2a once it is dispensed
from
20 the magazine 12 (see FIG. 1), an upper landing 23, on which is received the
dispensed lath 2a in the flat orientation after it has been pivoted (see FIG.
3), and
a riser 24 between the two. The riser 24 preferably defines a sloping angle.
The
lower landing 22, upper landing 23 and riser 24 may for example be embodied by
variations in the thickness of the support plate 21. During the positioning of
a
25 dispensed lath 2a, the support plate preferably moves at a generally
constant
speed in a forward direction (towards the right in FIGs. 1 to 9), and is
afterwards
retracted by translation in the opposite direction to get the next dispensed
lath.
The positioning mechanism 20 further comprises an actuator (not illustrated)
for
30 moving the support plate 21 back and forth along its horizontal course. The
actuator may be embodied by any actuator known in the art, such as for example
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a pneumatic, hydraulic or electric cylinder, a rotational cylinder, a screw, a
cogwheel, a pivot means or any combination thereof.
The positioning mechanism 20 preferably also includes a stopper 26. In the
illustrated embodiment of FIGs. 1 to 9, the stopper is embodied by a
structural
element having an elbow shape forming a substantially right angle. The angling
portion of the stopper may be rounded as shown. In accordance with a first
preferred variant of the invention, the height of the stopper 26 with respect
to the
level of the support plate 21 is fixed and the apparatus is then used for
placing
io laths of a single specific width. In accordance with a second variant of
the
invention, the height of stopper 26 is adjustable so as to adjust to any width
of lath.
The stopper 26 is positioned in proximity to the dispensing opening 13 of the
magazine 12, preferably slightly below and to the side, in the forward
direction of
travel of the support plate 21. In the preferred embodiment of the invention,
the
stopper 26 and the riser 24 of the support plate are designed and disposed to
impose together a torque on the dispensed lath 2a as it is being translated,
to
effect the required pivoting of the dispensed lath 2a in the flat orientation.
Although
a 90-degree elbow-shape stopper is shown in FIGs. 1 to 9, it is worth
mentioning
that any stopper capable of blocking a translational movement of the top part
of a
2o dispensed lath while it is being pushed towards the pick-up location is
considered
within the scope of the present invention.
The support plate 21 further preferably includes an abutment member 25, which
may for example have the shape of a rectangular block as shown. The abutment
member 25 may advantageously serve to push the dispensed lath 2a towards the
pick-up location 28 after it has been pivoted in the flat orientation, and
therefore
lies on the upper landing 23. Optionally, in the illustrated embodiment of
FIGs. 1 to
9, the abutment member 25 may also be in registry with the dispensing opening
13
of the magazine 12 for a portion of the travel of the support plate 21,
therefore
3o blocking the fall of the next lath 2b in the magazine 12 and preventing it
from being
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dispensed while the dispensed lath 2a is being translated, as better shown in
FIGs. 3 to 6.
The placing apparatus 10 also includes a gripping mechanism 16 in proximity to
5 the positioning mechanism 20. The gripping mechanism is selectively movable
between a retracted position and an extended position. In the retracted
position,
the gripping mechanism is adapted to grip the dispensed lath 2a having arrived
to
the pick-up location 28 (see FIGs. 4 to 6). Once the dispensed lath 2a has
been
properly gripped, the gripping mechanism 16 moves to the extended position (
see
lo FIG. 7) where it releases the dispensed lath 2a onto the tiered lumber
surface 6
(see FIG. 8). In the preferred embodiment, the gripping mechanism 16 then
moves
back to the retracted position (see FIG. 9) and remains retracted until the
next lath
arrives.
The gripping mechanism 16 may be embodied be any appropriate mechanism
allowing a lath beneath the mechanism to be picked-up and lowered towards, and
released on, a tier of lumber. In the preferred embodiment illustrated in
FIGs. 1 to
9, this mechanism 16 includes a wall member 30 receiving a first extremity 32
of
the dispensed lath which extends forward relative to the movement of the
2o dispensed lath 2a when it reaches the pick-up location 28. A rotatable
member 17,
which is rotatable about an axis perpendicular to the translation of the
support
plate, is also provided and preferably includes a pincer projection 18 which
comes
into contact with the second extremity 34 of the rear of the dispensed lath
2a. In
this manner, the dispensed lath 2a is firmly gripped between the wall member
30
and pincer projection 18. Preferably, the wall member 30 and rotatable member
17
are mounted on a frame 36 which is movable between the retracted and extended
positions. An appropriate actuator, such as for example a cylinder actuator
19, is
provided for moving the frame 36.
3o As will be readily understood by one skilled in the art, a variety of other
mechanisms could be used to embody the gripping mechanism and the present
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invention is not limited to the components described above. In one possible
variant, vacuum nozzles as described for example in US 5,863,176 could
alternatively be used.
Still referring to FIGs. 1 to 9, a method for placing laths on a tiered lumber
surface,
according to an embodiment using the apparatus described above, will be
described.
Referring to FIG. 1, the method includes a first step of holding a stack 14 of
laths 2
io or other elongated articles stacked in their upright orientation, that is,
on one of
their side surfaces as opposed to their flat surfaces. A magazine 12 may
advantageously be provided for this purpose. The method then includes a step
of
successively dispensing the lath 2, each thereby successively defining a
dispensed lath 2a. As will be noted in FIG. 1 in the embodiment illustrated
therein,
the dispensed lath 2a provides support for the next bottom-most lath 2b in the
magazine 12, preventing it from being dispensed at this stage of the method.
Referring to FIGs. 2 to 4, the method next includes a step of receiving the
dispensed lath 2a in its upright orientation, and translating it to a pick-up
location
2o 28 while pushing on the dispensed lath 2a to pivot it in the flat
orientation, as it is
being translated. In the preferred embodiment, the dispensed lath 2a is
received
on a support plate 21 as disclosed above, that is having a lower landing 22,
an
upper landing 23 and a riser 24 therebetween. The support plate 21 is moved
along a generally horizontal course. In the illustrated embodiment, the
support
plate moves generally from left to right at a preferably constant speed while
the
dispensed lath is being translated, and is retracted back to its original
position
once the dispensed lath 2a has reached the pick-up location. Preferably, the
dispensed lath 2a is first received on the lower landing 22 (see FIG. 1), and
is then
translated towards a stopper 26. As best seen in FIG. 2, the stopper 26 and
the
3o riser 24 of the support plate impose together a torque on the dispensed
lath 2a as
it is being translated to pivot it in the flat orientation. In practice, the
stopper
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pushes on the upper right side of the dispensed lath 2a, while the riser
pushes on
the lower left side, resulting in a torque. Once pivoted, the dispensed lath
2a is
preferably received on the upper landing 23 in its flat orientation, as best
seen in
FIG. 3. At this stage, an abutment member 25, preferably provided on the
support
plate 21 adjacent the upper landing 23, abuts on the rear side of the
dispensed
lath 2a and pushes on it towards the pick-up location (see FIG. 4). It will be
noted
that right after pivoting the dispensed lath 2a still provides support for the
next
bottom-most lath 2b in the magazine, but that this function is transferred to
the
abutment member 25 when it comes in registry with the magazine 12. Preferably,
lo the abutment member 25 keeps on preventing the next lath 2b from being
dispensed while the dispensed elongated article is being translated to the
pick-up
location and until the support plate 21 is retracted back to its original
position.
The method then includes a step of gripping the dispensed lath 2a once the
pick-
up location 28 has been reached, using an appropriate gripping mechanism 16.
Referring to FIGs. 5 and 6, it can be seen that it this embodiment a first
extremity
32 of the dispensed lath 2a is received against a wall member 30. A rotatable
member 17 having a pincer projection 18 preferably rotates about an axis
perpendicular to the moving of the support plate 21 so as to bring the pincer
projection 18 in contact with a second (rear) extremity 34 of the dispensed
lath 2a,
while the first (front) extremity 32 of the dispensed lath 2a reaches a wall
member
disposed at the end of its course. As can be seen on FIGs. 5 and 6, the pincer
projection 18 may act to push the dispensed lath 2a for the last portion of
its
course towards the wall member 30.
Once then dispensed lath 2a is firmly gripped and held between the pincer
projection 18 and wall member 30, the support plate is preferably translated
back
towards the magazine 12 and away from the dispensed lath 2a, as seen in FIG.
6.
In this manner the path underneath the dispensed lath 2a is cleared.
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Referring to FIG. 7, the method next includes a step of moving the gripped
dispensed lath 2a towards the tiered lumber surface 6. In the illustrated
embodiment, as explained previously, the components of the gripping mechanism
16 are mounted on a frame 36 which is vertically movable under the effect of
an
appropriate actuator, such as actuating cylinder 19.
Referring to FIG. 8, the method next includes a step of releasing the
dispensed
lath 2a onto the tiered lumber surface 6. This is preferably accomplished by
rotating the rotatable member 17 in a direction opposite to its previous
rotation,
1o thereby freeing the dispensed lath 2a from the grip of the pincer
projection 18.
Referring to FIG. 9, the gripping mechanism is shown being retracted back to
its
retracted position. It is to be noted in this figure that the support plate 21
has also
been retracted to its original position, and that the lower landing 22
receives the
next lath 2b to be dispensed now that it is no longer retained within the
magazine
12.
Referring to FIGs. 11 to 19, there is shown another embodiment of the present
invention. It will be noted that in these drawings, the movement of the
dispensed
lath is shown from right to left.
In this case, it will be noted that the stopper 26 is embodied by a rounded
wall
proximate the magazine 12. The rounded wall is preferably part of a frame
structure mounting the gripping mechanism 16. In this embodiment, a dampening
member 38 is provided for dampening the pivoting of the dispensed lath 2a. The
dampening member 38 preferably includes an arm 39 having a first extremity 40
pivotaAy mounted to the apparatus 10, and a second extremity 42 provided with
a
roller 44. The second extremity 42 projects towards the dispensing opening 13
so
that the roller 44 engages the dispensed lath 2a as it pivots (see FIG. 12).
The
presence of a dampening member may be advantageous for handling larger laths.
In the illustrated embodiment, the dampening member 38 is preferably disposed
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so that the roller 44 will engage the dispensed lath 2a only if it is larger
than a
predetermined thickness.
Although the dampening member has been shown herein as a pivoting arm, it will
be understood by one skilled in the art that it could be replaced by a device
which
is linerarly movable either vertically, horizontally or at an angle, by a
rotational
device, by a spring-actuated device or a combination of such devices.
Another particular feature of this embodiment is the addition of a retractable
holder
to 46 engaging the next lath to be dispensed 2b to retain it in the magazine
12. The
retractable holder is preferably spring actuated. As can be best seen in FIGs.
13 to
18, through the entire translation of the dispensed lath 2a towards the
gripping
mechanism 16, the retractable holder 46 applies pressure on one of the flat
surfaces of the next bottom-most lath 2b, pushing it against the opposite wall
of
the magazine 12.
Although a preferred embodiment of the present invention has been described in
detail herein and illustrated in the accompanying drawings, it is to be
understood
that the invention is not limited to this precise embodiment and that various
changes and modifications may be effected therein without departing from the
scope or spirit of the present invention.
