Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DEWATERING METHOD FOR CORRECTING WATER CONTENT OF GREEN
VENEER FOR PLYWOOD AND
APPARATUS FOR DEWATERING THE GREEN VENEER
BACKGROUND OF THE INVENTION
[Field of the Invention]
[0001]
The invention relates to a dewatering method for
correcting water contents of green veneers for plywood. In
the dewatering method, a pressure is vertically applied to
a large number of vertically laminated green veneers for
plywood so that the green veneers are compressed and dewatered
for reduction of water contents of the green veneers. The
invention also relates to an apparatus for dewatering the
green veneers.
[Description of the Related Art]
[0002]
Describing a plywood production process often employed,
a log being rotated is peeled into thin band plates by the
use of a lathe (plane) , green veneers are obtained by cutting
the peeled band plates in predefined dimensions and then dried,
and a plurality of the green veneers is bonded to produce the
plywood. In the process, the green veneers are compressed
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and dewatered by applying a pressure to the green veneers
before the drying step because it is time-consuming to
immediately dry the obtained green veneers.
[0003]
The water contents of the respective green veneers thus
dewatered are desirably as equal as possible not only among
the laminated green veneers but also in different parts of
each green veneer. A large difference between the water
contents leads to a lengthy drying step and makes it difficult
for the green veneers to be equally dried, in which case the
water contents are still different from one green veneer to
another and in different parts of one green veneer after the
drying step. When the green veneers thus having different
water contents are laminated to produce the plywood, warp
and/or distortion is likely to occur.
[0004]
Comparing sapwood and core pieces respectively
obtained from outer layers and a core part of the log, the
water contents of each green veneer before compressing step
are largely different. For example, the water content of the
sapwood is twice to three times as large as a relatively low
water content of the wood core. When the sapwood and core
pieces, each one of which is inadequate and unusable as a
veneer, are joined and used as a patched veneer, the veneer
may have water contents two-fold to three-fold different from
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one another in different parts of the patched veneer. In some
of such green veneers, there may be differences by several-ten
percentages or more among the water contents in different
parts of one green veneer.
[Patent Document 1] Japanese Laid-Open Patent
Publication No.2002-166403
[Patent Document 2] Japanese Laid-Open Patent
Publication No. 2010-197004
[0005]
The Patent Document 1 discloses a roller dewatering
apparatus. In the apparatus, green veneers are each
transported through between squeeze rollers to be thereby
pressed and dewatered. This apparatus which dewaters the
green veneers one by one needs an extensive time for its whole
operation. Further, the apparatus, wherein all of the green
veneers are uniformly pressed by the rollers, is unable to
correct a variability of water contents among the different
green veneers.
[0006]
The Patent Document 2 discloses a dewatering apparatus
configured for laminate collective compression. In the
apparatus, laminated green veneers are pressed collectively
from an upper direction to be dewatered. The apparatus thus
dewatering all of the green veneers at once achieves a better
dewatering efficiency. However, the apparatus is similarly
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unable to correct a variability of water contents, whether
they are different water contents among the green veneers
and/or different water contents in different parts of one
green veneer.
SUMMARY OF THE INVENTION
[Problem to be Solved by the Invention]
[0007]
The invention provides a method and an apparatus for
dewatering a plurality of green veneers while reducing a
variability of water contents during the dewatering
treatment.
[Means for Solving Problems and Operational Effect]
[0008]
The invention provides a dewatering method as described
below. A large number of green veneers for plywood
respectively having high water contents and formed in a
rectangular shape are vertically laminated to obtain a veneer
laminate having a quadrangular prismatic shape. Cut faces
of the green veneers for plywood, which are end faces of the
green veneers for plywood intersecting with a direction of
fibers, are vertically aligned. The veneer laminate is
located between upper and lower platen members so that two
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opposite side faces of the veneer laminate vertically form
cut face gathering planes. The upper and lower platen members
are moved toward each other to apply a pressing force to the
large number of laminated green veneers for plywood
5 constituting the veneer laminate. Accordingly, water
contained in the green veneers for plywood is drawn through
the cut faces of the green veneers and drips downward along
the cut face gathering planes vertically formed where the cut
faces of the green veneers for plywood are gathered. The
pressing force applied to the veneer laminate is released or
weakened while the water is dripping downward so that the cut
faces and fibers inside of the green veneers for plywood
spread in a direction of original shape of the green veneers,
generating a negative pressure. The water dripping downward
along the cut face gathering planes is suctioned into fibers
of the green veneer having a relatively low water content by
a suctioning action generated from the cut faces toward the
inside by the negative pressure. Consequently, a
variability of the water contents in the veneer laminate is
lessened among the green veneers for plywood and in different
parts of each of the green veneers for plywood while an overall
water content of the veneer laminate is reduced.
[0009]
The veneer laminate is thus pressed by the upper and
lower platen members to be dewatered and the pressing force
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applied to the veneer laminate is released or weakened while
the water is dripping along the cut faces (perpendicular
walls) of the veneer laminate. Therefore, the compressed
veneer laminate swells under its own elasticity, generating
the negative pressure in the fibers of the green veneers, and
the dripping water is suctioned into the fibers by the
negative pressure. Then, the water drawn from the green
veneer or parts of the green veneer having the water content
relatively high is transferred to the green veneer or parts
of the green veneer having the water content relatively low.
Thus, the green veneers are dewatered such that the water
contents have a less variability from one green veneer to
another and in different parts of one green veneer . Therefore,
the green veneers can be thereafter dried efficiently with
less time. When a plurality of green veneers is bonded to
obtain a sheet of plywood, the plywood obtained as a product
is unlikely to warp or distort because the water contents of
the green veneers used in the plywood are not as different
from one green veneer to another and/or in different parts
of one green veneer.
[0010]
According to an aspect of the invention, the pressing
force applied by the upper and lower platen members to the
veneer laminate may be repeatedly released or weakened a
plurality of times while the water drawn by the pressing force
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is dripping downward along the cut face gathering planes
vertically formed.
[0011]
According to the method, the water is transferred from
the green veneer or parts of the green veneer having the water
content relatively high to the green veneer or parts thereof
having the water content relatively low. Then, the green
veneers are compressed again so that the water is discharged
from the fibers of the green veneers. When the water
discharge, the water suction, and the water discharge again
are performed repeatedly, the green veneers can be dewatered
such that the variability of water contents is more
effectively lessened from one green veneer to another and/or
in different parts of one green veneer.
[0012]
The invention provides a green veneer dewatering
apparatus as described below. A large number of green veneers
for plywood are vertically laminated to obtain a veneer
laminate, and the veneer laminate is subject to a pressing
force vertically applied to the veneer laminate to be
compressed and dewatered to reduce a water content of the
veneer laminate. The apparatus includes:
a support platen supporting the veneer laminate;
a pressing member provided in an upper part of the
support platen and movable toward and away from the support
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platen;
a pressing cylinder adapted to drive and push the
pressing member against the veneer laminate;
a regulating member provided so as to vertically move
relative to the support platen, the regulating member being
adapted to stand upright from the support platen to be in
contact with or closely adjacent to perpendicular walls on
at least two opposite sides of the veneer laminate and thereby
regulate movement or extension of the veneer laminate while
the veneer laminate is being pressed by the pressing member,
the regulating member further being adapted to abut the
pressing member moving downward to thereafter move downward
integral with the pressing member;
a lifting and lowering device adapted to lift and lower
the regulating member to and from an upright standing
position; and
a control device adapted to control the pressing
cylinder which drives the pressing member.
[0013]
According to the apparatus, the regulating member
reduces a likelihood of fracture in end portions of the green
veneers that may be caused by the pressing force applied to
the veneer laminate, making it difficult for the green veneers
to be damaged by the dewatering treatment.
[0014]
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According to an aspect of the invention, the control
device controlling the pressing cylinder includes: a first
pressing stopper adapted to, in a step for subjecting the
veneer laminate to a first pressing performed by the pressing
member, release or weaken the pressing force applied by the
pressing member while the water contained in the veneer
laminate is being discharged from the veneer laminate by
controlling the pressing cylinder so that the first pressing
stops; and a second pressing starter adapted to restart the
application of the pressing force to the veneer laminate by
controlling the pressing cylinder so that a second pressing
is performed by the pressing member.
[0015]
Because the pressing force applied by the pressing
member is released or weakened while the water is dripping
along the perpendicular walls of the veneer laminate during
the first pressing, the compressed veneer laminate starts to
swell under its own elasticity, generating a negative
pressure in the fibers of the green veneers. Then, the water
dripping downward is suctioned by the negative pressure into
the fibers of the green veneers, and the water discharged from
the green veneer or any parts of the green veneer having the
water content relatively high is transferred to the green
veneer or parts of the green veneer having the water content
relatively low. When the veneer laminate is compressed again
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in the second pressing for further water discharge,
difference in the water contents are further reduced among
the green veneers and/or in different parts of one green
veneer during the dewatering treatment.
5 [0016]
According to another aspect of the invention, the
regulating member is positioned along the perpendicular walls
on two opposite sides of the veneer laminate in a direction
intersecting with the direction of fibers so that a stretch
10 of the veneer laminate in the direction intersecting with the
direction of fibers is regulated during the application of
the pressing force.
[0017]
This prevents or reduces a likelihood of any stretch
of the end portions of the green veneers in the direction
intersecting with the direction of fibers, making it
difficult for the end portions to fracture.
[0018]
According to still another aspect of the invention, the
apparatus includes a pair of the regulating members facing
each other along the perpendicular walls on opposite two sides
of the veneer laminate, and a lateral movement device adapted
to move one of the pair of the regulating members toward the
other regulating member. The lifting and lowering device
locates one of the pair of the regulating members at a standby
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position below a veneer supporting surface of the support
platen when ready to place the veneer laminate on the support
platen, and then lifts the one of the pair of the regulating
members so as to stand upright on the support platen after
the veneer laminate is placed on the support platen. The
lateral movement device moves the one of the pair of the
regulating members toward the other regulating member so that
the veneer laminate is thereby sandwiched from two sides
intersecting with the direction of fibers.
[0019]
According to the apparatus, neither of the regulating
members interferes with the veneer laminate when placed on
the support platen, and the veneer laminate is sandwiched by
the regulating members from two sides because one of the
regulating members is moved toward the other regulating
member after the veneer laminate is placed on the support
platen. As a result, any stretch and fracture of the end
portions of the green veneers are more effectively prevented
or less likely while the pressing force is being applied to
the green veneers.
[0020]
In the apparatus according to still another aspect of
the invention, a plurality of the pressing cylinders is
coupled at different positions with the pressing member of
pressing cylinders to drive the pressing member, and a
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plurality of lifting cylinders is coupled at different
positions with the pressing member. The lifting cylinders
are driven when the pressing member is lifted to return to
a lift-up position after the pressing of the veneer laminate
by the pressing member is over. The apparatus further
includes: a stroke distance measuring device adapted to
measure a stroke distance of each of the lifting cylinders
that follow the plurality of the pressing cylinders while the
plurality of the pressing cylinders is pressing the veneer
laminate by the use of the pressing member; and a per-cylinder
control device adapted to individually control the plurality
of the pressing cylinders so as to lessen a deviation between
the stroke distances of the lifting cylinders measured by the
measuring device or a tilt of the pressing member calculated
from the deviation.
[0021]
According to the apparatus, the lifting cylinders
having outputs relatively small but large enough to lift the
pressing member are used to return the pressing member to the
lift-up position, making it unnecessary to drive the pressing
cylinders with very large outputs. This leads to energy
saving. Further, in the apparatus, the stroke distances of
the plurality of lifting cylinders is measured and the
plurality of pressing cylinders is individually controlled
so that the tilt of the pressing member is corrected based
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on the measured values. The apparatus can horizontally
retain the veneer laminate as equally in height as possible
during the pressing, thereby evenly dewatering the veneer
laminate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022]
Fig. 1 is a front view conceptually and schematically
illustrating an apparatus suitably used in a dewatering
method according to the invention;
Fig. 2 is a front view which corresponds to Fig. 1,
illustrating a step of the dewatering method according to the
invention relevant to an operation of the apparatus;
Fig. 3 is a front view, similarly illustrating an
operation and a step of the method subsequent to the
illustration of Fig. 2;
Fig. 4 is a front view, similarly illustrating an
operation and a step of the method subsequent to the
illustration of Fig. 3;
Fig. 5 is a front view, similarly illustrating an
operation and a step of the method subsequent to the
illustration of Fig. 4;
Fig. 6 is a front view, similarly illustrating an
operation and a step of the method subsequent to the
illustration of Fig. 5;
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Fig. 7 is a front view, similarly illustrating an
operation and a step of the method subsequent to the
illustration of Fig. 6;
Fig. 8 is a front view, similarly illustrating an
operation and a step of the method subsequent to the
illustration of Fig. 7;
Fig. 9 is a front view, similarly illustrating an
operation and a step of the method subsequent to the
illustration of Fig. 8;
Fig. 10 is a front view, similarly illustrating an
operation and a step of the method subsequent to the
illustration of Fig. 9;
Figs. 11 are plan views, similarly illustrating
operations and steps of the method which correspond to the
illustrations of Figs. 4 and 5;
Fig. 12 is a plan view drawn to describe an effect of
Fig. 11;
Fig. 13 is another plan view drawn to describe the effect
of Fig. 11;
Fig. 14 is a schematic plan view drawn to describe the
effect of Fig. 11;
Fig. 15 is a front view of a veneer laminate Bl,
illustrating a function which corresponds to the illustration
of Fig. 7;
Fig. 16 is a side view of the illustration of Fig. 15.
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Fig. 17 is a perspective view of the illustration of
Fig. 15;
Fig. 18 is a conceptual view drawn to describe water
transfer in the veneer laminate El;
5 Fig. 19 is a plan view of a patched veneer;
Fig. 20A is a plan view illustrating water transfer in
the patched veneer of Fig. 19;
Fig. 20B is a front view of the illustration of Fig.
20A;
10 Figs. 21 are conceptual views illustrating water
discharge and suctioning mechanisms in green veneers which
correspond to the illustrations of Figs. 6 to 8;
Fig. 22 is a graph which confirms an effect accomplished
by the dewatering method according to the invention;
15 Fig. 23 is a drawing of an oil pressure system,
illustrating another apparatus suitably used in the
dewatering method according to the invention;
Fig. 24 is a drawing of a control system in the
illustration of Fig. 23;
Fig. 25 is a schematic front view of the apparatus,
illustrating an operation including lifting cylinders;
Fig. 26 is a front view, more specifically illustrating
the apparatus of Fig. 25;
Fig. 27 is a side view of the illustration of Fig. 26;
Fig. 28 is a plan view of a lower part in the illustration
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of Fig. 26;
Fig. 29 is a schematic illustration of operations of
a lateral movement device and a regulating member illustrated
in Figs. 26 to 28;
Fig. 30 is a front view which corresponds to Fig. 1,
illustrating still another apparatus suitably used in the
dewatering method according to the invention;
Fig. 31 is a front view illustrating a step subsequent
to the illustration of Fig. 30;
Fig. 32 is a front view illustrating a step subsequent
to the illustration of Fig. 31;
Fig. 33 is a schematic front view illustrating a first
example of a method for detecting dripping water;
Fig. 34 is a front view illustrating a second example
of the method;
Fig. 35 is a front view illustrating a third example
of the method; and
Fig. 36 is a front view illustrating a fourth example
of the method.
EXEMPLARY EMBODIMENT FOR CARRYING OUT THE INVENTION
[0023]
An exemplary embodiment of the invention is described
referring to examples illustrated in the accompanied drawings.
First, a dewatering apparatus for correcting water contents
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_
suitably used in a method according to the invention is
described. Then, examples of the method according to the
invention are described in a manner that corresponds to the
description of operations of the apparatuses. Fig. 1
illustrates a green veneer dewatering apparatus 1 adapted to
vertically apply a pressing force and thereby compress a
veneer laminate (green veneer laminate) composed of a large
number of vertically laminated green veneers for plywood to
dewater the veneer laminate for reduction of a water content
of the veneer laminate. The green veneer dewatering
apparatus 1 has a support platen 2 supporting the veneer
laminate, a press platen 3 provided in an upper section of
the support platen 2 and serving as a pressing member movable
toward and away from the support platen 2, a pressing cylinder
4 adapted to drive the press platen 3 and push the press platen
3 against the veneer laminate, a pair of regulating members
5 provided so as to vertically move relative to the support
platen 2, the regulating members 5 being adapted to stand
upright from the support platen 2 to be in contact with or
closely adjacent to perpendicular walls on at least two
opposite sides of the veneer laminate to thereby regulate
movement or stretch of the veneer laminate while the veneer
laminate is being pressed by the press platen 3, the
regulating members 5 further being adapted to abut the press
platen 3 moving downward to thereafter move downward integral
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with the press platen 3, a lifting and lowering cylinder 6,
which is an example of the lifting and lowering device,
adapted to lift and lower the regulating members 5 to and from
an upright standing position, and a pressing controller 7,
which is an example of the control device, adapted to control
the pressing cylinder 4 which drives the press platen 3. The
support platen 2 and the press platen 3 are examples of the
upper and lower platen members.
[0024]
The support platen 2, the pressing cylinder 4, and the
lifting and lowering cylinder 6 are secured to a frame 8. The
frame 8 is formed in a box shape, and the support platen 2
is located so as to horizontally traverse the frame 8. A
transport-in conveyer 11 which transports a veneer laminate
Bl to the support platen 2 is connected to one side of the
support platen 2, and a transport-out conveyer 12 which
transports a veneer laminate B2 already compressed and
dewatered from the support platen 2 is connected to the other
side of the support platen 2.
[0025]
The pair of regulating members 5 each has a planar
(plate-like) shape facing perpendicular walls on opposite two
sides of the veneer laminate B1 and stand upright in parallel
with each other. The green veneers have a square-like shape
(conventionally, rectangular shape). When a direction of
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fibers and a direction intersecting with the direction of
fibers are identified in the green veneer, the two
perpendicular walls on two sides are in parallel with the
direction of fibers. Therefore, a pair of the regulating
members 5 is facing each other in the direction intersecting
with the direction of fibers of the green veneers, and end
faces of the fibers of the green veneers are exposed in a
direction orthogonal to a plane of paper in the illustration
of Fig. 1. These end faces constitute cut face gathering
planes where cut faces of the green veneers are gathered.
[0026]
As an example of the lateral movement device, lateral
movement cylinders 13 and 13 are provided to move one of the
pair of regulating members 5 toward the other regulating
member 5. The lateral movement cylinders 13 and 13 are
respectively connected to the regulating members 5. The
lateral movement cylinders 13 and 13 are secured to lifting
and lowering bases 14, and piston rods 15 of lateral movement
cylinders 13 are coupled with the regulating members 5. The
pair of regulating members 5 each stands upright to extend
upward through moving spaces 16 formed in the support platen
2. The regulating members 5 are horizontally movable
relative to the lifting and lowering bases 14 while retaining
their upright positions within the moving spaces 16. When
at least one of the lateral movement cylinders 15 is driven
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to laterally move one of the regulating members 5 toward the
other regulating member 5, the veneer laminate B1 is thereby
sandwiched from two sides in the direction intersecting with
the direction of fibers.
5 [0027]
The lifting and lowering bases 14 are coupled with
piston rods 17 of lifting and lowering cylinders 6 and 6
vertically installed. The regulating members 5 are coupled
with the lifting and lowering cylinders 6 via the lifting and
10 lowering bases 14 which respectively support the lateral
movement cylinders 13. The lifting and lowering cylinders
6 each has a stroke which lifts and lowers each of the
regulating members 5 between an upright standing position
where an upper end of each of the regulating members 5
15 protrudes upward through the support platen 2 beyond a height
dimension of the veneer laminate Bl and a standby position
below an upper surface of the support platen 2. The lifting
and lowering cylinders 6 each has a vertical guide member
vertically formed, not illustrated in the drawings, which
20 directly guides each of the regulating members 5 upward and
downward or indirectly guides each of the regulating members
5 by the use of a fitment formed integral with each of the
regulating members 5. When the regulating member 5 on the
side of the transport-in conveyer 11 alone is at the standby
position below the upper surface of the support platen 2 in
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the apparatus illustrated in Fig. 1, the veneer laminate Bl
is transported onto the support platen 2. When at least the
regulating member 5 on the side of the transport-out conveyer
12 is at the standby position below the upper surface of the
support platen 2 in the apparatus, the dewatered veneer
laminate B2 is transported from the support platen 2.
[0028]
The support platen 2 has therein a built-in conveyer
20 adapted to lift itself slightly above the upper surface
of the support platen 2. The built-in conveyer 20 is, for
example, a chain conveyer driven being supported by sprockets
21 and 22 provided on both end sides of the support platen
2. The conveyer 20 is moved by a lifting and lowering device
23 (for example, lifting and lowering cylinder) to and from
a transport position slightly above the upper surface of the
support platen 2 and a standby position below the upper
surface. The built-in conveyer 20, when driven at the
transport position slightly above the upper surface, guides
the veneer laminate B1 transported by the transport-in
conveyer 11 to the support platen 2. When the conveyer 20
is retreated to the standby position, the veneer laminate B1
is placed on the upper surface of the support platen 2. The
dewatered veneer laminate B2 is slightly lifted when the
built-in conveyer 20 is lifted by the lifting and lowering
device 23 and transported by the built-in conveyer 20 from
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,
the support platen 2 toward the transport-out conveyer 12 and
thereby received by the transport-out conveyer 12.
[0029]
The pressing controller 7 which controls the pressing
cylinder 4 has a first pressing stopper adapted to, in a step
for subjecting the veneer laminate B1 to a first pressing
performed by the press platen 3, release or weaken a pressing
force applied by the press platen 3 while the water contained
in the veneer laminate Bl is being discharged from the veneer
laminate Bl by controlling the pressing cylinder 4 so that
the first pressing stops; and a second pressing starter
adapted to restart the application of the pressing force to
the veneer laminate B1 by controlling the pressing cylinder
4 so that a second pressing is performed by the press platen
3. More specifically, the pressing controller 7 includes:
at least a sequence program 25 run by a CPU to control a
pressing pattern of the pressing cylinder; and a timer 26
measuring pressing times and pressing-release times. The
controller 7 is connected to a pressure sensor 28 which
detects a pressure level of the pressing cylinder 4, an
electromagnetic valve 29 which controls a fluid pressure
(normally, oil pressure) to the pressing cylinder 29, and,
if necessary, a pressing force source such as an oil pressure
pump 30. The first pressing stopper and the second pressing
starter include the sequence program 25 and the timer 26.
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[0030]
Next, operation steps of the green veneer dewatering
apparatus 1 as described above are hereinafter described.
The description given below includes details of the sequence
program. 25 of the pressing controller 7 and an example of the
dewatering method for correcting water contents according to
the invention.
[0031]
When the veneer laminate B1 is transported by the
transport-in conveyer 11 as illustrated in Fig. 1, the
regulating member 5 on the side of the transport-in conveyer
11 is moved downward by the lifting and lowering cylinder 6
to the standby position below the upper surface of the support
platen 2 as illustrated in Fig. 2, whereas the other
regulating member 5 on the side of the transport-out conveyer
12 stays upright beyond the height dimension of the veneer
laminate Bl.
[0032]
Next, the built-in conveyer 20 illustrated in Fig. 1
is driven, and the veneer laminate Bl on the transport-in
conveyer 11 is received by the built-in conveyer 20 and then
placed on the support platen 2 as illustrated in Fig. 3. At
the time, the built-in conveyer 20 is slightly above the upper
surface of the support platen 2, and the veneer laminate Bl
on the built-in conveyer 20 is afloat. Then, the regulating
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member 5 below the support platen 2 is lifted from the support
platen 2 by the lifting and lowering cylinder 6 to a position
equal to the veneer laminate B1 in height or is lifted a little
beyond the position so as to protrude as illustrated in Fig.
4.
[0033]
Then, the regulating member 5 on the side of the
transport-in conveyer 11 is laterally moved in a small
distance by the lateral movement cylinder 13 toward the
regulating member 5 on the opposite side as illustrated in
Fig. 5. As a result, the veneer laminate B1 is sandwiched
by the pair of regulating members 5 from two sides. The
perpendicular wall on one side of the veneer laminate B1 in
the direction of fibers is butted to or located in close
proximity of an inner surface of the regulating member 5 on
the opposite side, while the perpendicular wall on the other
side in the direction parallel to fibers is butted to an inner
surface of the regulating member 5 laterally moved. After
that, the built-in conveyer 20 illustrated in Fig. 1 is moved
downward by the lifting and lowering device 23 to a position
lower than the support platen 2. Then, the veneer laminate
Bl is seated on the upper surface of the support platen 2.
[0034]
Then, the pressing cylinder 4 is driven, and the press
platen 3 thereby moves downward as illustrated in Fig. 6.
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During the downward movement, the press platen 3 abuts upper
ends of the pair of regulating members 5 protruding upward
from the upper face of the veneer laminate Bl. A drive
pressure of the pressing cylinder 4 is larger than pressures
5 (holding pressures) of the lifting and lowering cylinders 6
of the regulating members 5. After the press platen 3 abuts
the upper ends, therefore, the pressing cylinder 4 pushes the
pair of regulating members 5 downward while pushing the
pistons of the lifting and lowering cylinders 6 downward.
10 [0035]
As illustrated in Fig. 7, as soon as the press platen
3 is butted to the upper face of the veneer laminate El (green
veneer at the top) during the process, the veneer laminate
Bl starts to be compressed by the pressing force applied to
15 the veneer laminate Bl. Then, the press platen 3 driven by
the pressing cylinder 4 continues to apply the pressing force
to the veneer laminate Bl over a predetermined period of time
by moving the pair of regulating members 5 downward.
[0036]
20 The veneer laminate Bl is vertically compressed by the
pressing force thus applied to the veneer laminate BI and
thereby relatively reduced in height, and the water contained
in the respective green veneers is squeezed out through the
end faces of the green veneers in the direction of fibers (for
25 example, perpendicular wall on the front illustrated in Fig.
CA 02778862 2012-05-31
26
7) and drips downward. During the dewatering treatment, the
drive of the pressing cylinder 4 is suspended to release the
pressing force (make the pressing force zero) to the veneer
laminate B1 from the press platen 3 or weaken the pressing
force to a lower level as illustrated in Fig. 8. This is the
stop of the first pressing while the water is dripping.
[0037]
In a short period of time after the pressing stopped,
the pressing cylinder 4 is driven again to proceed to a second
pressing where the veneer laminate B1 starts to be pressed
again by the press platen 3 as illustrated in Fig. 9.
After the second pressing performed for a predetermined
short period of time, it is suitably selected whether the
dewatering treatment to the veneer laminate B1 is ended or
a third pressing starts after the second pressing stopped,
while the water squeezed out of the fibers of the green veneers
during the second pressing was dripping. As illustrated in
Fig. 10, the pressing cylinder 4 is driven to the backward
direction after an Nth pressing (N is an integer equal to or
larger than 2) is over, and the press platen 3 starts to move
upward and moves away from the upper face of the dewatered
veneer laminate B2 and the upper ends of the pair of regulating
members 5.
[0038]
Then, the regulating member 5 at least on the side of
CA 02778862 2012-05-31
27
the transport-out conveyer 12 is moved downward by the lifting
and lowering cylinder 6 until the upper end of the regulating
member 5 arrives at the standby position below the upper
surface of the support platen 2. The built-in conveyer 20
illustrated in Fig. 1 is moved upward by the lifting and
lowering device 23 so that the dewatered veneer laminate B2
is thereby lifted from the support platen 2 and ready to be
transported by the built-in conveyer 20. When the conveyer
20 is driven, the veneer laminate 52 moves away from the
support platen 2 and continues to be transported by the
transport-out conveyer 12 to a predefined site.
[0039]
The operation of the pressing cylinder in the N-times
pressing so far described is controlled by the sequence
program 25 run by the pressing controller 7 illustrated in
Fig. 1. The timer 26 is a structural element which decides
duration time of the respective pressing and the respective
pressing-release timing. When the times measured by the
timer 26 are equal to duration time of the respective pressing
times and pressing-release timing preset in the sequence
program, the pressing controller 7 transmits a signal to the
electromagnetic valve 29 and, if necessary, the pressing
force source 30 to suspend or restart the operation of the
pressing cylinder 4. When the pressure of the pressing
cylinder 4 obtained from the pressure sensor 28 and the times
CA 02778862 2012-05-31
28
measured by the timer 6 are used as parameters for deciding
timings of continuing and releasing the pressing force, the
application of the pressing force is continued or released
depending on several conditions described by logical
operation such as AND or OR, etc. when the measured pressing
force and times are equal to preset values or included in
preset numeral ranges.
[0040]
As a result of the lateral movement of one of the
regulating members 5 illustrated in Figs. 4 and 5, the veneer
laminate Bl is sandwiched by the regulating members 5 from
two sides as illustrated in plan views of Figs. 11. This not
only lessens or prevents any tilt or misshaping of the veneer
laminate B1 while the pressing force is applied to the veneer
laminate Bl but also lessens or prevents any stretch of the
end portions of the green veneers in the direction
intersecting with the direction of fibers of the green veneers
due to the pressing when the veneer laminate B1 is sandwiched
from two sides in the fiber-intersecting direction as
illustrated in Fig. 12.
[0041]
An unlimited stretch of the end portions is likely to
cause fractures in the end portions of the green veneers
(veneer laminate B1) in the direction of fibers as illustrated
in Fig. 13. However, the pair of regulating members 5 can
CA 02778862 2012-05-31
29
prevent the occurrence of such a stretch and resulting
fractures in the end portions, as illustrated in Fig. 14.
[0042]
Figs. 15 to 18 and 21 are conceptual views (images) of
situations of the veneer laminate Bl after the first pressing
starts and stops as illustrated in Figs. 7 to 8 and the second
pressing thereafter starts as illustrated in Fig. 9. When
the veneer laminate B1 is compressed by the pressing force
in the first pressing as illustrated in Figs. 15 and 16, the
water is squeezed from the fibers of the green veneers and
drips downward along the perpendicular walls of the veneer
laminate Bl. Fig. 21A conceptually illustrates the veneer
laminate before the pressing starts, and Fig. 21B
conceptually illustrates the veneer laminate currently being
pressed. As illustrated in Figs. 21A to 210, when the
pressing force is released (or weakened) while the water is
dripping, the compressed fibers of the green veneers start
to swell trying to regain the original shape, and a negative
pressure is thereby generated in the fibers of the green
veneers. Under the influence of the negative pressure thus
generated, the water dripping along or staying on the wall
surfaces of the veneer laminate Bl is suctioned into the
fibers of the green veneers. This suctioning under the
negative pressure more markedly occurs in the green veneer
or any parts of the green veneer relatively containing less
CA 02778862 2012-05-31
water than the green veneer or any parts thereof relatively
containing more water.
[0043]
Accordingly, between the fibers of laminated green
5 veneers bl and the fibers in different parts of each of the
green veneers bl, the water transfer occurs from the green
veneer having a high water content to the green veneer having
a low water content or from any parts of one green veneer having
a high water content to the other parts of the green veneer
10 having a low water content. In other words, a negative
pressure pumping action exerted by the green veneers per se
when the pressing force is released during the dewatering of
the green veneers serves to equalize the water contents in
the whole structure of the veneer laminate Bl.
15 [0044]
Generally, there maybe a relatively small variability
of the water contents in one green veneer. To make use of
a plurality of different pieces of wood, each one of which
is inadequate and unusable as a veneer (inferior pieces of
20 a log with holes or ruptures, or fragments of the pieces
generated when the log with cavities, knots, or uneven
periphery is cut), they may be j oined by means of, for example,
a tape, so that a patched veneer is formed and used as a
material of plywood similarly to one-piece green veneers
25 normally obtained. In a patched veneer bll illustrated in
CA 02778862 2012-05-31
31
Fig. 19, for example, a sapwood piece A (from outer layer)
of a cedar tree, a heartwood piece B (from mid layer) , a sapwood
piece C, and a core piece D (from center) are patched together.
There are differences in the water contents of these pieces;
twice to three times as different between the sapwood pieces
A and C having high water contents and the core piece D having
a low water content, and the water content of the heartwood
piece B is somewhere between the water contents of these
pieces. The negative pressure pumping action, which
repeatedly applies the pressing force, release the pressing
force, and applies the pressing force again, can more
effectively transfer the water particularly between parts of
the patched veneer bll having more different water contents,
thereby equalizing the water contents in the patched veneer
bll. This is not a technical advantage limited to the patched
veneer. In different parts of a green veneer obtained from
a cedar tree, for example, the water content of a part may
be larger or smaller by 20% to 150% than the other. Such a
large variability is successfully lessened.
[0045]
The water content equalizing effect thus far described
is more enhanced as the release of the pressing force is
repeated more often while the green veneers are being pressed
and dewatered. Therefore, the pumping action (negative
pressure suctioning) is desirably performed a plurality of
CA 02778862 2012-05-31
32
times such that first pressing, release of first pressing
while the water is dripping, second pressing, release of
second pressing while the water is dripping, third pressing,
release of third pressing while the water is dripping ... .
[0046]
To improve a dewatering efficiency by reducing a length
of time of the dewatering treatment, it is necessary to
coordinate how many times the pressing and pressing release
should be repeated and a length of time of the dewatering
necessary for one veneer laminate Bl. A suggestion for
reducing the dewatering time to the minimum is to complete
the dewatering treatment for one veneer laminate Bl in three
steps; first pressing, release of first pressing, and second
pressing.
[0047]
Fig. 22 is a graph illustrating an effect of the
dewatering treatment in the veneer laminate Bl described so
far (particularly, effect of equalizing post-dewatering
water contents). In a dewatering test performed according
to the method described so far, water contents of the sapwood
pieces were about 100% to 300% at most with such a large
difference of 203% in an initial stage (before the dewatering
treatment). However, the variability of the water contents
was reduced to 95% after the dewatering treatment according
to the invention. The variability was further reduced to 5%
CA 02778862 2012-05-31
33
after the drying treatment subsequent to the dewatering
treatment.
[0048]
The cedar core showed the water contents of about 50%
to 150% at most with the water content difference of 99% in
the initial stage (before the dewatering treatment). The
water content difference was reduced to 70% after the
dewatering treatment and further reduced to 7% after the
drying treatment.
[0049]
Next, another example of the invention is described
referring to an apparatus illustrated in Figs. 23 to 29.
As is clear from an oil pressure system illustrated in
Fig. 23, the apparatus used in the example includes a
plurality of (four in this example) pressing cylinders 50
which pressurize the veneer laminate B1 from an upper
direction. The pressing cylinders 50 are coupled with a press
platen 51 which is an example of the pressing member, and the
pressing cylinders 50 are connected to an oil pressure source
53 (compressor or oil pressure pump) through electromagnetic
valves 52 of the pressing cylinders 50. A plurality of (for
example, two each on two sides of the press platen 51, four
in total) lifting cylinders 54 is coupled with the press
platen 51 in parallel with the pressing cylinders 50 to be
located on outer sides of the pressing cylinders 50. The
CA 02778862 2012-05-31
,
34
lifting cylinders 54 are all connected to the oil pressure
source 53 through a common electromagnetic valve 55. As
illustrated in Fig. 24, each of the electromagnetic valves
52 of the plurality of pressing cylinders 50 is connected to
a controller (oil pressure controller) 57, and the
electromagnetic valve 55 of the plurality of lifting
cylinders 54 is also connected to the controller 57.
[0050]
As illustrated in Fig. 25, the lifting cylinders 54 each
has a linear encoder 58 incorporated in the lifting cylinders
54 or attached to the lifting cylinders 54 as a measuring
device which measures a stroke (operation) distance (stretch
distance of piston rods 54a). The encoders 58 are connected
to the controller 57. When the pressing cylinders 50 are
stretched to press the veneer laminate Bl by the use of the
press platen 51, the piston rods 54a of the four lifting
cylinders 54 are stretched as the press platen 51 is moving
downward. During the stretch, the linear encoders 58 measure
stroke distances (stretch distances of the piston rods 54a)
Li, L2, L3, and L4 of the lifting cylinders 54 and outputs
measured values of the distances to the controller 57.
[0051]
Depending on a difference between the output values of
the encoders 58 (deviation AL) or a three-dimensional tilt
AO of the press platen 51 calculated from the output value
CA 02778862 2012-05-31
deviation AL, the controller 57 controls the electromagnetic
valves 52 of the pressing cylinders 50 (Figs. 23 and 24) so
that the deviation AL or the tilt AO are reduced to the minimum.
Further, the controller 57 separately controls working
5 pressures P1 to P4 of the pressing cylinders. As a result,
the tilt of the press platen 51 relative to the veneer laminate
B1 is corrected. The piston rods 54a of the lifting cylinders
54 illustrated in Fig. 25, therefore, are coupled rotatably
(through a small degree) relative to the press platen 51. The
10 piston rods 50a of the pressing cylinders 50 may be configured
to abut the press platen 51 by means of, for example, hooks
not illustrated in the drawings.
[0052]
When the press platen 51 is lifted to a lift-up position
15 after the veneer laminate B1 is pressed and dewatered by the
pressing cylinders 50, the pressing cylinders 50 are not
driven but the lifting cylinders 54 alone are driven (a fluid
pressure is supplied from the pressure source 53 through the
electromagnetic valve 55) to elevate the press platen 51 to
20 the lift-up position (original position) . At the time, the
piston rods 50a of the plurality of pressing cylinders 50
shrink following the actions of the lifting cylinders 54. A
force for simply lifting the press platen 51 is obtained from
the application of a cylinder pressure large enough to
25
overcome the weight of the press platen 51. If such a cylinder
CA 02778862 2012-05-31
36
pressure is applied by the pressing cylinders 50 with large
outputs, a very large pressure is needed to drive the heavy
pistons. However, as far as the small-sized lifting
cylinders 54 with low outputs are used to apply such a cylinder
pressure, the press platen 51 can be lifted and returned to
the original position by a small cylinder pressure and a low
energy.
[0053]
The lifting cylinders 54 are stretched in response to
the actions of the pressing cylinders 50 (downward movement
of the press platen 51), and the strokes are plotted by the
encoders 58. Then, the pressing cylinders 50 are separately
controlled based on the deviation AL or the tilt AO used as
a parameter. Accordingly, the lifting cylinders 54 may be
used without additionally providing a specific mechanism to
correct the tilt of the press platen 51 during the application
of the pressing force. Further, the veneer laminate Bl can
be equalized in height and thereby evenly dewatered.
[0054]
Figs. 26 and 27 specifically illustrate a positional
relationship between the pressing cylinders 50 and the
lifting cylinders 54. The pressing cylinders 50 are secured
to inside of a frame 60 which is a securing member of the
apparatus, and the lifting cylinders 54 is secured to an outer
side of the frame 60. Referring to Fig. 27, the piston rods
CA 02778862 2012-05-31
37
54a of the lifting cylinders 54 are coupled with the press
platen 51 by pins 54b (for example, rotatable
two-dimensionally or three-dimensionally on at least one of
shafts X and Y).
[0055]
As illustrated in Fig. 26, an upper surface of a support
platen 61 is used as a support surface 61a supporting the
veneer laminate B1 placed on the upper surface of a support
platen 61. A chain conveyer (built-in conveyer) 62 is
provided in parallel with the support surface 61a. The
conveyer 62 has endless raceways 63 in two rows provided such
that they are hidden immediately below the support surface
61a (for example, chains), cyclic sprockets 64 and 65 which
support the chains 63 so that these chains cyclically go
around, a plurality of support sprockets 66 subject to loads
acting on the chains 63, a conveyer frame 67 which supports
the sprockets 64 to 66, a motor 68 supported by the frame 67
which drives the chains 63, and a conveyer lifting and
lowering cylinder 69 which lifts and lowers the whole
structural elements by the use of the frame 67.
[0056]
As illustrated in Fig. 28, the upper surface of the
support platen 61 (support surface 61a) has chain grooves
(slits) 70 for the chains 63 to travel through. The chains
63 in two rows are lifted and lowered in the chain grooves
CA 02778862 2012-05-31
38
70 by the conveyer lifting and lowering cylinder 69 to and
from a transport position slightly higher than the upper
surface of the support platen 61 and a standby position lower
than the upper surface. While the veneer laminate Bl is being
pressurized, the chains 63 are at the standby position. When
the veneer laminate B1 is transported to and from the support
platen 61, the chains 63 are lifted by the conveyer lifting
and lowering cylinder 69 to the transport position. A drive
shaft (sprocket) 71 illustrated in Fig. 26 is provided to make
the chains 63 in two rows go around in synchronization with
each other. The rotation of the motor 68 is transmitted to
the sprockets 65 and 71 through a driving mechanism such as
a chain, and the chains 63 are thereby synchronously driven.
[0057]
In the illustration of Fig. 26, regulating members 72
which regulate positions of two opposite sides (two faces)
of the veneer laminate Bl are supported relative to lateral
movement members 73 standing upright so that the regulating
members 72 can be vertically lifted and lowered by the use
of lifting and lowering guides 74 as schematically
illustrated in Fig. 29. Lifting and lowering cylinders 75
which lift the regulating members 72 are secured to the
lateral movement members 73, and piston rods 75a of the
lifting and lowering cylinders 75 are coupled with the
regulating members 72. The lateral movement members 73 are
CA 02778862 2012-05-31
39
supported in the frame 60 of the apparatus by the lateral
movement cylinders (lateral movement devices) 76. When the
lateral movement cylinders 76 are put in action, the
regulating members 72, the lateral movement devices 73, and
the lifting and lowering cylinders 75 are all laterally
(horizontally) move at once in a given range of distances.
[0058]
When the lifting and lowering cylinders 75 are
operating (stretching), the regulating members 72 move upward
under the guidance by the lifting and lowering guides 74 of
the lateral movement members 73. As illustrated in Fig. 26,
the two regulating members 72 facing each other regulate the
positions of opposite two end faces of the veneer laminate
Bl. As illustrated in Fig. 29, the regulating members 72 are
moved horizontally by the lateral movement cylinders 76 by
the use of lateral movement members 73, and the veneer
laminate Bl staying afloat which is supported by the chain
conveyer 62 is sandwiched by the regulating members 72.
[0059]
Fig. 28 is a plan view specifically illustrating the
structure schematically illustrated in Fig. 29. On right and
left sides of the drawing are illustrated the structural
elements at vertically different positions, however, the
apparatus in practical use is basically laterally symmetrical.
The chains 63 of the chain conveyer 62 are located in the tracks
CA 02778862 2012-05-31
of the regulating members 72 moving upward and downward.
Therefore, the regulating members 72 are respectively
provided with relief grooves (slits) 77 to avoid any
interference with the chains 63. The relief grooves 77 are
5 vertically formed in an enough length to meet the strokes of
the regulating members 72 moving upward and downward. The
lateral movement cylinders 76 are secured to the frame 60 at
positions in front and back of a depth direction of the support
plate 61 so as to extrude the lateral movement cylinders 76
10 from the frame 60 of the apparatus to the outside at the side
of the apparatus, and the lateral movement members 73 standing
upright are coupled with the cylinders 76.
[0060]
The regulating members 72 are located on inner sides
15 of the lateral movement members 73, in other words,
respectively between the lateral movement members 73 and the
frame 60. The regulating members 72 are supported by the
lateral movement members 73 by the use of the lifting and
lowering guides 74 so as to move upward and downward and moved
20 to
right and left in the illustration of Fig. 28 by the lateral
movement cylinders 76. Though not illustrated in Fig. 28,
the lateral movement cylinder 76 is provided on the left of
the drawing similarly to the lateral movement cylinder 76 on
the right, and functions similarly thereto. On the left of
25 the drawing is illustrated a lateral movement guide 78, which
CA 02778862 2012-05-31
,
41
_
functions as a linear guide which couples the lateral movement
member 73 with the frame 60 at a position different in height
to the lateral movement cylinder 76 at positions in front and
back of a depth direction of the support plate 61 to guide
the lateral movement member 73 to right and left in the drawing.
Though not illustrated in Fig. 28, a lateral movement linear
guide is similarly provided on the right of the drawing to
guide the lateral movement member 73 on the right to
horizontally move.
[0061]
As illustrated in Fig. 27, the regulating members 72
have longitudinal frame portions 79 and 80 which are
rectangular pipe materials each formed in a frame shape,
lateral frame portions 81 and 82 which vertically connect the
longitudinal frame portions, inner spaces of the frame
portions 79 to 82, and plate members 83 which seal the spaces.
The relief grooves (slits) 77 in the up-down direction are
respectively formed in the longitudinal frame portions 79 and
80 so as to fit the chains 63 in two rows. The piston rods
75a of the lifting and lowering cylinders 75 secured to the
lateral movement members 73 are coupled with a lower surface
of the lateral frame portion 81 on the upper side.
[0062]
As illustrated in Fig. 27, the up and down movement of
the press platen 51 is guided by the lifting and lowering guide
CA 02778862 2012-05-31
42
74 formed in the frame 60. A pair of upper stoppers 51a
(stopper portions) are formed on a lower surface of the press
platen 51 with an interval therebetween equal to the
outer-side intervals of the pair of regulating members 72 (for
example, long enough to meet a width dimension of the
regulating member 72 as illustrated in Fig. 27) . When the
press platen 51 moving downward make contact with the upper
ends of the pair of regulating members 72, the pair of upper
stoppers 51a are in close proximity of the outer surfaces of
the regulating members 72, thereby preventing the pair of
regulating members 72 from opening outward during the
application of the pressing force.
[0063]
Describing the basic operation in the example described
so far, similarly to the example illustrated referring to Figs.
1 to 21, after the veneer laminate B1 is transported onto the
support platen 61 by the chain conveyer 62 driven by the motor
68 while the regulating member 72 on the left in Fig. 26
protrudes from the support platen 61 and the regulating member
72 on the right is receded from the support platen 61, the
regulating member 72 on the right in Fig. 26 then protrudes
from the support platen 61. When the regulating member 72
thus protruding is laterally moved by the lateral movement
cylinder 76 toward the regulating member 72 on the left, the
veneer laminate B1 is sandwiched by these regulating members
CA 02778862 2012-05-31
43
,
72, and the conveyer lifting and lowering cylinder 69 moves
the chain conveyer 62 downward. Then, the veneer laminate
B1 is placed on the upper surface (support surface) 61a of
the support platen 61.
[0064]
Then, the pressing cylinders 50 are driven, and the
press platen 51 accordingly moves downward and abuts the upper
ends of the pair of regulating members 72. Then, the press
platen 51 driven by the pressing cylinders 50 compresses the
veneer laminate B1 by pushing the regulating members 72
downward to squeeze the water contained in the veneer laminate
Bl. During the process, the stroke distances Li to L4 of the
plurality of lifting cylinders 54 that follow the pressing
cylinders are plotted, and the plurality of pressing
cylinders 50 is separately controlled so that the press platen
51 is not tilted, in other word, the veneer laminate B1 is
horizontally retained equally in height.
[0065]
When the pressing force applied by the pressing
cylinders 50 is released or weakened, the compressed fibers
of the green veneers start to swell, and a negative pressure
is thereby generated in the fibers of the green veneers.
Under the influence of the negative pressure thus generated,
the water dripping along the perpendicular walls of the veneer
laminate B1 is suctioned into the green veneer or any parts
CA 02778862 2012-05-31
44
of the green veneer relatively containing less water. As a
result, the water contents are more efficiently equalized in
the green veneers and the whole structure of the veneer
laminate Bl. Further, the regulating members 72 regulate any
stretch of the end portions of the green veneers in the
direction intersecting with the direction of fibers, thereby
reducing a likelihood of any fractures in the end portions.
[0066]
When the dewatering treatment for equalizing the water
contents is completed after the pressing and the pressing
release (or the pressing force is reduced) are performed by
the pressing cylinder 50 a suitable number of times (for
example, once to three times), the regulating members 72
illustrated in Fig. 26 are both moved downward to a lift-down
position by the lifting and lowing cylinders 75. Then, the
chain conveyer 62 is elevated by the conveyer lifting and
lowering cylinder 69 to lift the dewatered veneer laminate
B2 from the support surface 61a of the support platen 61. The
chain conveyer 62 driven by the motor 68 transports the veneer
laminate B2 from the support platen 61. Then, the same steps
are performed for the next veneer laminate Bl.
[0067]
The example described so far succeeded in reducing the
variability of the water contents as illustrated in Fig. 22.
[0068]
CA 02778862 2012-05-31
The apparatuses illustrated in Figs. 1, 25, and 26
respectively have the regulating members 5 and 72, the lifting
and lowering cylinders 6 and 75 which move the regulating
members 5 and 72 upward and downward, the lateral movement
5 cylinders 13 and 76 which laterally move the regulating
members 5 and 72, and the lifting cylinders 54. According
to the dewatering method in which the apparatuses are used,
the veneer laminate B1 sandwiched by the regulating members
5 and 72 is pressed from upward. As illustrated in Fig. 30,
10 the method according to the invention may be performed by a
dewatering apparatus l' having such a simple structure that
the support platen 2 and the press platen 3 are principal
structural elements. The dewatering apparatus 1' does not
include the regulating members 5 and 72, the lifting and
15 lowering cylinders 6 and 75 which move the regulating members
5 and 72 upward and downward, the lateral movement cylinders
13 and 76 which laterally move the regulating members 5 and
72, and the lifting cylinders 54 (other structural
characteristics are similar to the illustrations of Figs. 1,
20 25, and 26).
[0069]
When the apparatus l' is used, the veneer laminate Bl
placed on the support platen 2 is pressed by the press platen
3 moved downward by the pressing cylinder 4. The pressing
25 force applied by the pressing cylinder 4 is released or
CA 02778862 2012-05-31
46
weakened while the water contained in the veneer laminate B1
thus pressed is squeezed through the cut faces of the veneer
laminate El and dripping downward. A negative pressure is
accordingly generated in the cut faces of the veneer laminate
Bl, and the water dripping downward is suctioned into the
fibers. Then, the pressing force is preferably applied again
(second pressing) as illustrated in Fig. 32, and the veneer
laminate Bl is dewatered so that the water contents in the
veneer laminate Bl are less variable. After the dewatering
treatment is over, the press platen 3 returns to the lift-up
position, and the dewatered veneer laminate B2 is discharged.
Then, the same steps are performed for the next veneer
laminate El.
[0070]
In the example described thus far, the veneer laminate
Bl is pressed to be dewatered, and the pressing force applied
by the press platen 3 is released or weakened while the water
is dripping downward. The timer 26 illustrated in Figs. 1
and 30 maybe used to determine based on test values previously
obtained that the water is still dripping within a time ti
after the pressing started, and the drive pressure of the
pressing cylinder 4 may be released or weakened in response
to a time-up signal of the time ti as a trigger. However,
a different member may be used in place of the timer 26 as
described below.
CA 02778862 2012-05-31
47
[0071]
As illustrated in Fig. 33, image pickup cameras 80, for
example, may be installed in place of the timer near the cut
face gathering planes (perpendicular walls) of the veneer
laminate Bl. Image data of the cameras 80 is transmitted to
the controller 7 (pressing controller), and the pressing
controller 7 determines that the water pressed out of the
veneer laminate is dripping downward when data indicating the
dripping water, in other words, image (moving image) data
including downward displacement is extracted from the image
data, and the pressing controller 7 outputs a signal for
releasing or weakening the drive pressure of the pressing
cylinder 4 to the pressing cylinder 4 (to be precise,
electromagnetic valve) while the water is still dripping.
The water dripping on the side faces of the veneer laminate
Bl travels through a water passage 91 formed in the support
platen 2 to be collected by a tub 92 and then discharged from
the tub 92.
[0072]
As illustrated in Fig. 34, reflection sensors 83, such
as optical sensors, maybe provided so as to face the cut face
gathering planes of the veneer laminate Bl. Reflection
signals, which are output from the reflection sensors 83 in
response to water screens, water drops, or water stream while
the water is dripping and reflected by the water screens on
CA 02778862 2012-05-31
48
the cut face gathering planes and returned, are transmitted
to the pressing controller 7, and the pressing controller 7
determines that the water is dripping on the cut face
gathering planes of the veneer laminate B1 as far as levels
of the reflection signals are equal to or larger than a
predetermined threshold value and outputs a signal for
releasing or weakening the drive pressure of the pressing
cylinder 4 to the electromagnetic valve of the pressing
cylinder 4.
[0073]
As illustrated in Figs. 35, at least sound sensors 84
and/or temperature sensors 85 may be provided near the cut
face gathering planes (perpendicular walls) of the veneer
laminate Bl. During the water is dropping, output levels of
the sound sensors 84 which picked up the sound of the dripping
water are equal to a certain value or higher, the temperature
sensors 85 output values within a temperature variation or
a predetermined temperature range because of the water
dripping, and the pressing controller 7 checks at least one
of the output signals of the sound sensors 84 and/or the
temperature sensors 85 to release or weaken the drive pressure
of the pressing cylinder 4.
[0074]
As illustrated in Fig. 36, a container 86 may be provided
to receive the water dripping along the cut face gathering
CA 02778862 2012-05-31
49
planes of the veneer laminate B1 through the water passage
91 of the support platen 2. A weight sensor 87 measures a
weight increase of the container 86 where the dripping water
is stored. As long as the water is dripping, the weight of
the container 86 where the water is stored keeps increasing.
Therefore, the pressing controller 7, to which a signal from
the weight sensor 87 is transmitted, determines whether an
amount of the water stored in the container 86 increases based
on the signal output from the weight sensor 87. The pressing
controller 7, which detected any increase, outputs a signal
for releasing or weakening the drive pressure of the pressing
cylinder 4 during the increase to induce the compressed veneer
laminate B1 to regain the original shape (swell) , so that the
water is suctioned into the fibers of the green veneers by
a negative pressure suctioning action caused by the swell.
[0075]
In the illustrations of Figs. 33 to 36, detecting
devices (80 to 87) which detect the water dripping are
provided respectively on the cut face gathering planes of the
veneer laminate B1 opposite to each other in parallel.
However, these detecting devices (80 to 87) may be provided
on one of the cut face gathering planes alone.
