Note: Descriptions are shown in the official language in which they were submitted.
CA 02488299 2004-11-23
LAMINATING PRESS
BACKGROUND OF THE INVENTION
Field of the Invention
[00011 The present invention relates generally to lamination processes and
apparatuses and, more particularly, to a laminating press suited for making
laminated
beams.
Description of the Prior Art
[00021 A variety of laminated wood beams are used in construction work
today as joists, girders, posts, columns or other structural pieces. Laminated
wood
beams are known to be stronger, more resistant and more dimensionally stable
than
continuous wood beams.
[00031 The laminated beams are made from stack of individual laminae
coated with an adhesive and then maintained face to face in compression while
the
adhesive is allowed to set.
[00041 The prior art laminating presses used to maintain the stacks of laminae
in compression are relatively complex, cumbersome and generally very costly to
purchase.
SUMMARY OF THE INVENTION
[00051 It is therefore an aim of the present invention to provide a new
laminating press which is relatively simple and economical.
[00061 It is also an aim of the present invention to provide a laminating
press
which is of compact construction.
[000'71 Therefore, in accordance with an aspect of the present invention,
there
is provided a laminating press comprising a frame, a conveyor mounted to said
frame,
and a plurality of press units adapted to individually receive respective
stacks of
individual laminae and press the laminae together face to face so as to
independently
form in parallel a corresponding number of laminated products, the press units
being
mounted along the conveyor and displaceable thereby between a loading position
and
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a discharged position while individually holding their respective stacks of
laminae in
compression.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Having thus generally described the nature of the invention, reference
will now be made to the accompanying drawings, showing by way of illustration
a
preferred embodiment thereof, and in which:
[0009] Fig. 1 is a perspective view of a beam-laminating press in accordance
with an embodiment of the present invention;
[00010] Fig. 2 is a side elevation view of the beam-laminating press shown in
Fig. 1;
[00011] Fig. 3 is an enlarged side view of an edge aligning system forming
part
of the beam-laminating press shown in Fig. 1;
[00012] Fig. 4 is a side view of a backstop mechanism forming part of the
beam-laminating press shown in Fig. l; and
[00013] Figs. 5a and Sb are schematic side views of an automatic release
system forming part of the beam-laminating press shown in Fig. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[00014] Fig. 1 illustrates an embodiment of a laminating press 10 suited for
making laminated cross lumber beams or timbers B composed of a plurality of
elongated wood pieces bonded together face to face.
[00015] The laminating press 10 generally comprises an infeed conveyor 11
for feeding the press 10 with individual laminae, for instance elongated wood
planks,
a frame 12 defining an inclined plane on which is mounted a hydraulic conveyor
14, a
plurality of individual press units 16 (13 in the illustrated example) fixedly
mounted
at regular intervals along the conveyor 14 and driven thereby, an edge
aligning
system 18 mounted on a side of the infeed conveyor 11 opposite the frame 12,
and a
discharge conveyor 20 extending parallel to the infeed conveyor 11 underneath
the
lower end of the frame 12 for successively receiving laminated beams B from
the
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individual press units 16. The inlet and discharge conveyors 11 and 20 are
preferably
provided in the form of endless belt conveyors and are of conventional
construction.
[00016] The frame 12 is made from heavy sturdy steel tubes assembled to each
other such as by welding. The frame 12 is configured to support the hydraulic
conveyor 14 carrying the press units 16 at an angle of about preferably 45
degrees
while providing the required clearance for the passage of the press units 16
on the
return run or bottom run of the conveyor 14 as shown in Figs 1 and 2. Mounting
the
conveyor 14 at an angle is advantageous in that it provides for significant
space
saving and, thus, important operating cost reductions
[00017] The hydraulic conveyor 14 comprises a plurality (five in the
illustrated
embodiments) of laterally spaced-apart endless chains 22 trained about pairs
of
longitudinally spaced-apart sprockets 24a and 24b. The top and bottom
sprockets 24a
and 24b are mounted to respective axles extending transversally at the top and
bottom
ends of the frame 12, respectively. At least one of the axles, preferably the
one at the
top end of the frame 12, is driven by a hydraulic motor 26 (Fig. 2) through a
chain
transmission 28 to drive the laterally spaced-apart endless chains 22 in
unison in
either one of a forward direction and a backward direction. As shown in Fig.
4, the
chain transmission includes a sprocket wheel 38. A backstop mechanism 40 is
selectively engageable with the sprocket wheel 38 to substantially eliminate
the back
loads on the hydraulic motor 26, thereby allowing using a smaller and less
expensive
motorization to drive the chains 22 and, thus, the press units 16. It also
advantageously provides for the use of a bi-directional motor.
[00018] The backstop mechanism 40 includes a pawl 42 in the form of a small
pivoted latch selectively engageable with the teeth of the sprocket wheel 38
to lock
the same against clockwise rotation. As shown in Fig. 4, the pawl 42 is
pivoted
between an idle position and a locking position (shown in broken lines) by a
small
pneumatic or hydraulic cylinder 44. The pawl 42 is normally maintained in its
idle
position by cylinder 44.
[00019] As shown in Figs. 1 and 2, each press section 16 includes a stationary
jaw or platen 52, for instance in the form of an elongated rectangular tube
member
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fixedly secured to the endless chains 22 of the conveyor 14 and extending
transversally with respect thereto, a stack support preferably provided in the
form of a
number of upstanding backing members 54 extending at right angles from the
stationary jaw 52 at regular intervals therealong to form a side arresting
surface for
the stack of laminae to be pressed bonded together, an elongated plate 56
extending
parallel to the stationary jaw 52 to unitize the backing members 54 at the end
thereof
opposite to the stationary jaw 52, a movable jaw or platen comprising a number
of
movable jaw segments 58 operated by pairs of pneumatic actuators 60 mounted to
the
elongated plate 56. The pneumatic actuators 60 are preferably provided in the
form of
pneumatic dampers or chock absorbers of the type used in truck and tractor
suspensions. The use of that type of fluid driven actuator is advantageous in
that it
provides for the application of a uniform pressure all along the length of the
stack of
laminae and prevents the wood from being damaged. The use of pneumatic
actuators
instead of hydraulic cylinders is also advantageous in that it permits to
reduce the size
of each press units, which results in savings in operating and maintenance
costs. Each
movable jaw segment 58 is displaceable toward and away from the stationary jaw
52
to press and release the stack of elongated laminae loaded in the press units
16. The
movable jaw segments 58 permit to apply individual pressing load along the
stack of
elongated laminae, thereby allowing accommodating variations in the height of
the
stack along the length thereof. The application of punctual pressing loads
provides
added flexibility. The above-described press unit 16 is advantageous in that
it
provides for the lamination of beams of various thickness, width, length and
type of
wood without variations in the quality of the final product. However, it is
understood
the movable jaw segments 58 could be replaced by a continuous elongated jaw or
platen. Also, the elongated plate 56 could be replaced by a number of plate
segments
pairing the baking members 54 and supporting a pair of pneumatic actuators 60.
[00020] As shown in Figs. 5a and Sb, each press unit 16 is further provided
with an automatic pressure release system 61 to automatically release a stack
of
bonded laminae directly onto the discharge conveyor 20 each time a press unit
16
engages a triggering arm 63 fixed on one side of the lower end of the frame
12. More
particularly, the system 61 comprises a valve 65 displaceable from a closed
position
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(Fig. 5a) for maintaining the pressure within the pneumatic actuators 60 to an
open
position (Fig. 5b) for purging the fluid pressure from the actuators 60,
thereby
allowing the bonded laminae to drop by gravity onto the discharge conveyor 20.
The
valve 65 is displaced between the open and closed positions thereof by an
actuating
lever 67. As shown in Figs. 5a and Sb, while the press unit 16 is driven
forward by
the conveyor 14 , the lever 67 contacts the triggering arm 63 which causes the
lever
67 to pivot in the direction indicated by arrow 69 to the position shown in
Fig. 5b,
thereby causing the pressure in the pneumatic actuators 60 to be released.
[00021] As best shown in Figs. 2 and 3, the edge aligning system 18 comprises
a frame 62, a number of laterally spaced-apart pivot arms 64 pivotally mounted
to the
frame 62 and operated by respective hydraulic cylinders 66 (four in the
illustrated
example) which are, in turn, pivotally mounted between the frame 62 and the
pivot
arms 64. The arms 64 are rigidly link together at their upper ends by a cross
tubular
member 68. A number of spring-loaded pressing members 70 are pivotally mounted
at regular intervals along the cross tubular member 68. As shown in Fig. 3,
each
spring-loaded pressing member 70 comprises a pusher 72 mounted for sliding
movement on a series of pins 74 extending at right angles from a base member
76.
Springs 80 are mounted about the pins 74 between the base member 76 and the
pusher 72. As shown in Fig. 2, the cylinders 66 are retracted to cause the
pivot arms
64 to pivot from an idle position (shown in broken lines) to an operational
position in
which the pusher 72 are pressed against the side edges of the stack of laminae
that
has just been loaded in one of the press units 16. By so conjointly applying
the
pushers 72 against the side edges of the stack of laminae, the offsets between
each of
the laminae can be reduced before the laminae be pressed bonded together face
to
face by the pressing unit 16 in which the stack has been loaded. This system
contributes to reduce wood fibre waste.
[00022] In operation, individual elongated laminae, such as elongated wood
members, are fed lengthwise to the press 10 via the infeed conveyor 11. The
hydraulic conveyor 14 is operated to position one of the press units 16 at a
loading
position at the bottom of the frame 12, as shown in Figs. 1 and 2. Then, the
conveyor
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14 is stopped and pawl 42 is engaged with sprocket wheel 38 to prevent the
transmission of backlash forces to the motor 26.
[000231 The press unit 16 to be loaded with a stack of laminae is preferably
stopped at an angle to the infeed conveyor 11, as shown in Fig. 2. The
individual
laminae are then manually stacked into the press unit 16. It is understood
that the
opposed faces of the laminae are covered with an adhesive. It is also
understood that
depending on the length of the laminae, more than one stack could be placed
end-to-
end into a same press unit 16 in order to simultaneously form a corresponding
number of laminated beams.
[00024] Once the individual laminae have been properly stacked into the press
unit 16, the cylinders 66 of the edge-aligning system 18 are retracted to
cause the
pushers 72 to press the stack of laminae against the backing members 54 of the
press
unit 16 in order to appropriately align the laminae with respect to each
other. While
the stack of laminae is held at the sides thereof between the pushers 72 and
the
backing members 54, the pneumatic actuators 60 of the press unit 16 are
connected
by the operator to a source of pneumatic pressure to cause the mobile jaw
segments
58 to move towards the fixed jaw 52, thereby pressing the laminae face to
face. The
pneumatic actuators 60 are pressurized to the desired pressure and then
disconnected
from the pneumatic source. Thereafter, the hydraulic cylinders 66 are expanded
to
cause the arms 64 to pivot back to their idle position (shown in broken lines
in Fig.
2), thereby moving the pushers 72 away from the compressed stack of laminae
held
between the mobile jaw 58 and the fixed jaw 52 of the press unit 16.
[00025 The hydraulic conveyor 14 is then powered back to bring the next
press unit 16 in position for receiving and compressing another stack of
laminae as
per the procedure described hereinabove. The press units 16 are, thus,
sequentially
loaded. While the press units 16 are carried about the loop defined by the
conveyor
14, the mobile jaw segments 58 are maintained press against the stacks of
laminae to
cure the beams. During the setting period, the press units 16 are sequentially
brought
to an unloading position at the lower end of the return line of the conveyor
14 above
the discharge conveyor 20. The press units 16 are sequentially unloaded each
time a
press unit 16 completes its run about the conveyor 14 and passes by the
triggering
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arm 65. Once the actuating lever 67 of the valve 65 of the pneumatic actuators
60 of
the press unit 16 passing by the triggering arm 63 has been rotated to its
open
position, as shown in Fig. 5b, the pressure exerted by the mobile jaw segments
58 on
the laminated beam is released and the beam falls down by gravity onto the
discharge
conveyor 20. Guards 82 are preferably fixedly mounted on the endless chains 22
between each press unit 16 to ensure that the laminated beams fall onto the
discharge
conveyor 20 and not on a side thereof. The guards 82 are preferably provided
in the
form of upstanding tubular members slightly inclined to the vertical in a
direction
away from the press units 16 located immediately downstream thereof with
respect to
the direction of travel of the press units 16 (i.e. the counter clockwise
direction in the
embodiment illustrated in Fig. 1).
[00026 The above described press 10 is cheaper and simpler than
conventional laminating press of equivalent capacity. Furthermore, it is of
compact
construction which results in important cost savings.
[0002'7] While a detailed description of an embodiment of the present
invention has been given, it is understood that many changes and modifications
may
be made without departing from the spirit of the invention. All such
modifications are
intended to be included within the scope of the appended claims.
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